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D'Angelo DC, Stephens SE, Jensen MO, Thomas LR. Design, fabrication, and evaluation of 3-D-printed cystotomy spoons as a retrieval method in dogs. Am J Vet Res 2023; 84:1-8. [PMID: 37507119 DOI: 10.2460/ajvr.23.02.0038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 07/12/2023] [Indexed: 07/30/2023]
Abstract
OBJECTIVE Current cystotomy methods often implement the use of off-label devices, resulting in urocystolith extraction difficulty and potentially leading to postoperative complications and discomfort for the patient. The objective of this study was to create 3 novel 3-D printed cystotomy spoons that offer a dedicated solution for removing urocystoliths from a patient's urinary bladder. ANIMALS Clinical use of the 3 novel 3-D printed cystotomy spoons were ultimately evaluated in 4 dogs and 1 cat that presented for urocystotlith removal at 3 different veterinary hospitals in northwest Arkansas. METHODS The novel cystotomy spoons were designed using SolidWorks, 3-D printed with a Dental Surgical Guide resin, and underwent prototype testing that included chlorhexidine soaking, autoclave sterilization, 3-point bend testing, and Finite Element Analysis. The efficiency of the spoons was then evaluated through a limited proof-of-concept study utilizing a postoperative questionnaire for the participating clinicians. RESULTS Practitioner feedback indicated positive experiences using 1 or more of the novel 3-D printed cystotomy spoons while performing a cystotomy surgery. However, successful use of the spoons was ultimately limited to dogs in the 23 to 34 kg weight range. CLINICAL RELEVANCE Novel 3-D printed cystotomy spoons have the potential to mediate urocystolith extraction difficulty and reduce postoperative complications. Additionally, this research demonstrates how veterinarians might develop custom 3-D models and prints to meet patient-specific needs. As such, further development could impact the standard of healthcare and the veterinary industry by promoting the use of additive manufacturing in veterinary medicine.
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Affiliation(s)
- Davina C D'Angelo
- Department of Animal Sciences, Dale Bumpers College of Agricultural, Food and Life Sciences, University of Arkansas, Fayetteville, AR
| | - Sam E Stephens
- Department of Biomedical Engineering, College of Engineering, University of Arkansas, Fayetteville, AR
| | - Morten O Jensen
- Department of Biomedical Engineering, College of Engineering, University of Arkansas, Fayetteville, AR
- Department of Surgery, University of Arkansas for Medical Sciences, Little Rock, AR
| | - Lauren R Thomas
- Department of Animal Sciences, Dale Bumpers College of Agricultural, Food and Life Sciences, University of Arkansas, Fayetteville, AR
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van Kampen A, Morningstar JE, Goudot G, Ingels N, Wenk JF, Nagata Y, Yaghoubian KM, Norris RA, Borger MA, Melnitchouk S, Levine RA, Jensen MO. Utilization of Engineering Advances for Detailed Biomechanical Characterization of the Mitral-Ventricular Relationship to Optimize Repair Strategies: A Comprehensive Review. Bioengineering (Basel) 2023; 10:601. [PMID: 37237671 PMCID: PMC10215167 DOI: 10.3390/bioengineering10050601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 05/10/2023] [Accepted: 05/12/2023] [Indexed: 05/28/2023] Open
Abstract
The geometrical details and biomechanical relationships of the mitral valve-left ventricular apparatus are very complex and have posed as an area of research interest for decades. These characteristics play a major role in identifying and perfecting the optimal approaches to treat diseases of this system when the restoration of biomechanical and mechano-biological conditions becomes the main target. Over the years, engineering approaches have helped to revolutionize the field in this regard. Furthermore, advanced modelling modalities have contributed greatly to the development of novel devices and less invasive strategies. This article provides an overview and narrative of the evolution of mitral valve therapy with special focus on two diseases frequently encountered by cardiac surgeons and interventional cardiologists: ischemic and degenerative mitral regurgitation.
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Affiliation(s)
- Antonia van Kampen
- Division of Cardiac Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
- Leipzig Heart Centre, University Clinic of Cardiac Surgery, 02189 Leipzig, Germany
| | - Jordan E. Morningstar
- Department of Regenerative Medicine and Cell Biology, University of South Carolina, Charleston, SC 29425, USA
| | - Guillaume Goudot
- Cardiac Ultrasound Laboratory, Department of Cardiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Neil Ingels
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR 72701, USA
| | - Jonathan F. Wenk
- Department of Mechanical Engineering, University of Kentucky, Lexington, KY 40508, USA;
| | - Yasufumi Nagata
- Cardiac Ultrasound Laboratory, Department of Cardiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Koushiar M. Yaghoubian
- Division of Cardiac Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Russell A. Norris
- Department of Regenerative Medicine and Cell Biology, University of South Carolina, Charleston, SC 29425, USA
| | - Michael A. Borger
- Leipzig Heart Centre, University Clinic of Cardiac Surgery, 02189 Leipzig, Germany
| | - Serguei Melnitchouk
- Division of Cardiac Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Robert A. Levine
- Cardiac Ultrasound Laboratory, Department of Cardiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Morten O. Jensen
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR 72701, USA
- Department of Surgery, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
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Crimmins-Pierce LD, Bonvillain GP, Henry KR, Hayat MA, Villafranca AA, Stephens SE, Jensen HK, Sanford JA, Wu J, Sexton KW, Jensen MO. Critical Information from High Fidelity Arterial and Venous Pressure Waveforms During Anesthesia and Hemorrhage. Cardiovasc Eng Technol 2022; 13:886-898. [PMID: 35545752 DOI: 10.1007/s13239-022-00624-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 04/08/2022] [Indexed: 01/27/2023]
Abstract
PURPOSE Peripheral venous pressure (PVP) waveform analysis is a novel, minimally invasive, and inexpensive method of measuring intravascular volume changes. A porcine cohort was studied to determine how venous and arterial pressure waveforms change due to inhaled and infused anesthetics and acute hemorrhage. METHODS Venous and arterial pressure waveforms were continuously collected, while each pig was under general anesthesia, by inserting Millar catheters into a neighboring peripheral artery and vein. The anesthetic was varied from inhaled to infused, then the pig underwent a controlled hemorrhage. Pearson correlation coefficients between the power of the venous and arterial pressure waveforms at each pig's heart rate frequency were calculated for each variation in the anesthetic, as well as before and after hemorrhage. An analysis of variance (ANOVA) test was computed to determine the significance in changes of the venous pressure waveform means caused by each variation. RESULTS The Pearson correlation coefficients between venous and arterial waveforms decreased as anesthetic dosage increased. In an opposing fashion, the correlation coefficients increased as hemorrhage occurred. CONCLUSION Anesthetics and hemorrhage alter venous pressure waveforms in distinctly different ways, making it critical for researchers and clinicians to consider these confounding variables when utilizing pressure waveforms. Further work needs to be done to determine how best to integrate PVP waveforms into clinical decision-making.
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Affiliation(s)
| | - Gabriel P Bonvillain
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR, USA
| | - Kaylee R Henry
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR, USA
| | - Md Abul Hayat
- Department of Electrical Engineering, University of Arkansas, Fayetteville, AR, USA
| | - Adria Abella Villafranca
- Department of Biomedical Informatics, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Sam E Stephens
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR, USA
| | - Hanna K Jensen
- Department of Surgery, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Joseph A Sanford
- Department of Anesthesiology, University of Arkansas for Medical Sciences, Little Rock, AR, USA
- Department of Biomedical Informatics, University of Arkansas for Medical Sciences, Little Rock, AR, USA
- Institute for Digital Health and Innovation, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Jingxian Wu
- Department of Electrical Engineering, University of Arkansas, Fayetteville, AR, USA
| | - Kevin W Sexton
- Department of Surgery, University of Arkansas for Medical Sciences, Little Rock, AR, USA
- Department of Biomedical Informatics, University of Arkansas for Medical Sciences, Little Rock, AR, USA
- Institute for Digital Health and Innovation, University of Arkansas for Medical Sciences, Little Rock, AR, USA
- Department of Health Policy and Management, University of Arkansas for Medical Sciences, Little Rock, AR, USA
- Department of Pharmacy Practice, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Morten O Jensen
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR, USA.
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Wood K, Stephens SE, Xu F, Hazaa A, Meek JC, Jensen HK, Jensen MO, Wickramasinghe R. In Vitro Blood Clot Formation and Dissolution for Testing New Stroke-Treatment Devices. Biomedicines 2022; 10:biomedicines10081870. [PMID: 36009417 PMCID: PMC9405282 DOI: 10.3390/biomedicines10081870] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 07/18/2022] [Accepted: 07/23/2022] [Indexed: 12/30/2022] Open
Abstract
Strokes are among the leading causes of death worldwide. Ischemic stroke, due to plaque or other buildup blocking blood flow to the brain, is the most common type. Although ischemic stroke is treatable, current methods have severe shortcomings with high mortality rates. Clot retrieval devices, for example, can result in physically damaged vessels and death. This study aims to create blood clots that are representative of those found in vivo and demonstrate a new method of removing them. Static blood clots were formed using a 9:1 ratio of whole sheep blood and 2.45% calcium chloride solution. This mixture was heated in a water bath at 37 °C for approximately one hour until solidified. Following clot solidification, human plasmin was introduced by various methods, including soaking, injection, and membrane perfusion, and the resulting dissolution percentages were determined. Different clot types, representative of the wide range found physiologically, were also manufactured and their dissolution characteristics evaluated. A method to reproducibly create blood clots, characteristic of those found in vivo, is essential for the production of stroke retrieval devices that can efficiently and effectively remove clots from patients with low mortality rates and little/no damage to the surrounding vessels.
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Affiliation(s)
- Kayla Wood
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR 72701, USA; (K.W.); (S.E.S.); (F.X.); (A.H.)
| | - Sam E. Stephens
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR 72701, USA; (K.W.); (S.E.S.); (F.X.); (A.H.)
| | - Feng Xu
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR 72701, USA; (K.W.); (S.E.S.); (F.X.); (A.H.)
| | - Alshaimaa Hazaa
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR 72701, USA; (K.W.); (S.E.S.); (F.X.); (A.H.)
| | - James C. Meek
- Interventional Radiology Clinic, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA;
| | - Hanna K. Jensen
- Departments of Radiology and Surgery, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA;
| | - Morten O. Jensen
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR 72701, USA; (K.W.); (S.E.S.); (F.X.); (A.H.)
- Correspondence: (M.O.J.); (R.W.); Tel.: +1-479-575-4216 (M.O.J.); +1-479-575-8475 (R.W.)
| | - Ranil Wickramasinghe
- Ralph E Martin Department of Chemical Engineering, University of Arkansas, Fayetteville, AR 72701, USA
- Correspondence: (M.O.J.); (R.W.); Tel.: +1-479-575-4216 (M.O.J.); +1-479-575-8475 (R.W.)
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Elmer KM, Bean MJ, Uretsky BF, Stephens SE, Jensen HK, Jensen MO. Customizable Angioplasty Balloon-Forming Machine: Towards Precision Medicine in Coronary Bifurcation Lesion Interventions. J Cardiovasc Transl Res 2022; 15:1119-1128. [PMID: 35312960 DOI: 10.1007/s12265-022-10229-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Accepted: 02/25/2022] [Indexed: 10/18/2022]
Abstract
The ability to customize the size and shape of angioplasty balloons may be useful in many clinical and research applications of coronary and endovascular intervention. Fully customizable balloons are outside the reach of most researchers due to their prohibitive cost. A small-scale balloon-forming machine was developed to produce fully customizable balloons. This study describes the creation of this customizable balloon-forming machine and identifies the key components of manufacturing a patient-specific balloon. Using a standard balloon-shaped mold created with a novel application of 3D stereolithography-printed resin, 104 PET balloon formation tests were conducted. A statistical study was conducted in which molding temperature and inflation air pressure were independent variables ranging from 100 to 130 °C and from 3.7 to 6.8 atm, respectively. The criteria for balloon-forming success were defined; pressure and temperature combined were found to have a significant impact on the success (p = 0.011), with 120 °C and 4.76 atm resulting in the highest chance for success based on a regression model.
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Affiliation(s)
- Kaitlyn M Elmer
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR, USA
| | - Maxwell J Bean
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR, USA
| | - Barry F Uretsky
- Department of Internal Medicine, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Sam E Stephens
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR, USA
| | - Hanna K Jensen
- Departments of Surgery and Radiology, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Morten O Jensen
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR, USA.
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Stephens SE, Kammien AJ, Paris JC, Applequist AP, Ingels NB, Jensen HK, Rodgers DE, Cole CR, Wenk JF, Jensen MO. In Vitro Mitral Valve Model with Unrestricted Ventricular Access: Using Vacuum to Close the Valve and Enable Static Trans-Mitral Pressure. J Cardiovasc Transl Res 2022; 15:845-854. [PMID: 34993757 PMCID: PMC9256857 DOI: 10.1007/s12265-021-10199-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 12/13/2021] [Indexed: 11/27/2022]
Abstract
Current in vitro models of the left heart establish the pressure difference required to close the mitral valve by sealing and pressurizing the ventricular side of the valve, limiting important access to the subvalvular apparatus. This paper describes and evaluates a system that establishes physiological pressure differences across the valve using vacuum on the atrial side. The subvalvular apparatus is open to atmospheric pressure and accessible by tools and sensors, establishing a novel technique for experimentation on atrioventricular valves. Porcine mitral valves were excised and closed by vacuum within the atrial chamber. Images were used to document and analyze closure of the leaflets. Papillary muscle force and regurgitant flow rate were measured to be 4.07 N at 120 mmHg and approximately 12.1 ml/s respectively, both of which are within clinically relevant ranges. The relative ease of these measurements demonstrates the usefulness of improved ventricular access at peak pressure/force closure.
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Affiliation(s)
- Sam E Stephens
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR, USA
| | - Alexander J Kammien
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR, USA
| | - Jacob C Paris
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR, USA
| | - Alexis P Applequist
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR, USA
| | - Neil B Ingels
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR, USA
| | - Hanna K Jensen
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR, USA.,Department of Surgery, University of Arkansas for Medical Sciences, Fayetteville, AR, USA
| | - Drew E Rodgers
- Department of Anesthesiology, Washington Regional Medical Center, Fayetteville, AR, USA
| | - Charles R Cole
- Department of Cardiovascular Surgery, Washington Regional Medical Center, Fayetteville, AR, USA
| | - Jonathan F Wenk
- Department of Mechanical Engineering, University of Kentucky, Lexington, KY, USA
| | - Morten O Jensen
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR, USA.
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Al-Alawi AZ, Henry KR, Crimmins LD, Bonasso PC, Hayat MA, Dassinger MS, Burford JM, Jensen HK, Sanford J, Wu J, Sexton KW, Jensen MO. Anesthetics affect peripheral venous pressure waveforms and the cross-talk with arterial pressure. J Clin Monit Comput 2021; 36:147-159. [PMID: 33606187 PMCID: PMC8894218 DOI: 10.1007/s10877-020-00632-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 12/09/2020] [Indexed: 11/30/2022]
Abstract
Analysis of peripheral venous pressure (PVP) waveforms is a novel method of monitoring intravascular volume. Two pediatric cohorts were studied to test the effect of anesthetic agents on the PVP waveform and cross-talk between peripheral veins and arteries: (1) dehydration setting in a pyloromyotomy using the infused anesthetic propofol and (2) hemorrhage setting during elective surgery for craniosynostosis with the inhaled anesthetic isoflurane. PVP waveforms were collected from 39 patients that received propofol and 9 that received isoflurane. A multiple analysis of variance test determined if anesthetics influence the PVP waveform. A prediction system was built using k-nearest neighbor (k-NN) to distinguish between: (1) PVP waveforms with and without propofol and (2) different minimum alveolar concentration (MAC) groups of isoflurane. 52 porcine, 5 propofol, and 7 isoflurane subjects were used to determine the cross-talk between veins and arteries at the heart and respiratory rate frequency during: (a) during and after bleeding with constant anesthesia, (b) before and after propofol, and (c) at each MAC value. PVP waveforms are influenced by anesthetics, determined by MANOVA: p value < 0.01, η2 = 0.478 for hypovolemic, and η2 = 0.388 for euvolemic conditions. The k-NN prediction models had 82% and 77% accuracy for detecting propofol and MAC, respectively. The cross-talk relationship at each stage was: (a) ρ = 0.95, (b) ρ = 0.96, and (c) could not be evaluated using this cohort. Future research should consider anesthetic agents when analyzing PVP waveforms developing future clinical monitoring technology that uses PVP.
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Affiliation(s)
- Ali Z Al-Alawi
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR, USA
| | - Kaylee R Henry
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR, USA
| | - Lauren D Crimmins
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR, USA
| | - Patrick C Bonasso
- Division of Pediatric Surgery, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Md Abul Hayat
- Department of Electrical Engineering, University of Arkansas, Fayetteville, AR, USA
| | - Melvin S Dassinger
- Division of Pediatric Surgery, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Jeffrey M Burford
- Division of Pediatric Surgery, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Hanna K Jensen
- Department of Surgery, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Joseph Sanford
- Department of Anesthesiology, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Jingxian Wu
- Department of Electrical Engineering, University of Arkansas, Fayetteville, AR, USA
| | - Kevin W Sexton
- Department of Surgery, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Morten O Jensen
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR, USA.
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Bonasso PC, Sexton KW, Mehl SC, Golinko MS, Hayat MA, Wu J, Jensen MO, Smith SD, Burford JM, Dassinger MS. Lessons learned measuring peripheral venous pressure waveforms in an anesthetized pediatric population. Biomed Phys Eng Express 2019. [DOI: 10.1088/2057-1976/ab0ea8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Bonasso PC, Sexton KW, Hayat MA, Wu J, Jensen HK, Jensen MO, Burford JM, Dassinger MS. Venous Physiology Predicts Dehydration in the Pediatric Population. J Surg Res 2019; 238:232-239. [PMID: 30776742 DOI: 10.1016/j.jss.2019.01.036] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 12/01/2018] [Accepted: 01/11/2019] [Indexed: 10/27/2022]
Abstract
BACKGROUND No standard dehydration monitor exists for children. This study attempts to determine the utility of Fast Fourier Transform (FFT) of a peripheral venous pressure (PVP) waveform to predict dehydration. MATERIALS AND METHODS PVP waveforms were collected from 18 patients. Groups were defined as resuscitated (serum chloride ≥ 100 mmol/L) and hypovolemic (serum chloride < 100 mmol/L). Data were collected on emergency department admission and after a 20 cc/kg fluid bolus. The MATLAB (MathWorks) software analyzed nonoverlapping 10-s window signals; 2.4 Hz (144 bps) was the most demonstrative frequency to compare the PVP signal power (mmHg). RESULTS Admission FFTs were compared between 10 (56%) resuscitated and 8 (44%) hypovolemic patients. The PVP signal power was higher in resuscitated patients (median 0.174 mmHg, IQR: 0.079-0.374 mmHg) than in hypovolemic patients (median 0.026 mmHg, IQR: 0.001-0.057 mmHg), (P < 0.001). Fourteen patients received a bolus regardless of laboratory values: 6 (43%) resuscitated and 8 (57%) hypovolemic. In resuscitated patients, the signal power did not change significantly after the fluid bolus (median 0.142 mmHg, IQR: 0.032-0.383 mmHg) (P = 0.019), whereas significantly increased signal power (median 0.0474 mmHg, IQR: 0.019-0.110 mmHg) was observed in the hypovolemic patients after a fluid bolus at 2.4 Hz (P < 0.001). The algorithm predicted dehydration for window-level analysis (sensitivity 97.95%, specificity 93.07%). The algorithm predicted dehydration for patient-level analysis (sensitivity 100%, specificity 100%). CONCLUSIONS FFT of PVP waveforms can predict dehydration in hypertrophic pyloric stenosis. Further work is needed to determine the utility of PVP analysis to guide fluid resuscitation status in other pediatric populations.
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Affiliation(s)
- Patrick C Bonasso
- Department of Pediatric Surgery, University of Arkansas for Medical Sciences, Little Rock, Arkansas.
| | - Kevin W Sexton
- Department of Surgery, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Md Abul Hayat
- Department of Electrical Engineering, University of Arkansas, Fayetteville, Arkansas
| | - Jingxian Wu
- Department of Electrical Engineering, University of Arkansas, Fayetteville, Arkansas
| | - Hanna K Jensen
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, Arkansas
| | - Morten O Jensen
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, Arkansas
| | - Jeffrey M Burford
- Department of Pediatric Surgery, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Melvin S Dassinger
- Department of Pediatric Surgery, University of Arkansas for Medical Sciences, Little Rock, Arkansas
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Bonasso PC, Sexton KW, Hayat A, Al-Alawi A, Wu J, Jensen HK, Jensen MO, Smith SD, Burford JM, Dassinger MS. Venous Physiology Predicts Anesthetic Induced Hypotension in Infants. J Am Coll Surg 2018. [DOI: 10.1016/j.jamcollsurg.2018.08.313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Bonasso PC, Dassinger MS, Jensen MO, Smith SD, Burford JM, Sexton KW. Optimizing peripheral venous pressure waveforms in an awake pediatric patient by decreasing signal interference. J Clin Monit Comput 2018; 32:1149-1153. [PMID: 29511972 DOI: 10.1007/s10877-018-0124-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 03/02/2018] [Indexed: 11/25/2022]
Abstract
The purpose of this technological notes paper is to describe our institution's experience collecting peripheral venous pressure (PVP) waveforms using a standard peripheral intravenous catheter in an awake pediatric patient. PVP waveforms were collected from patients with hypertrophic pyloric stenosis. PVP measurements were obtained prospectively at two time points during the hospitalization: admission to emergency department and after bolus in emergency department. Data was collected from thirty-two patients. Interference in the PVP waveforms data collection was associated with the following: patient or device motion, system set-up error, type of IV catheter, and peripheral intravenous catheter location. PVP waveforms can be collected in an awake pediatric patient and adjuncts to decrease signal interference can be used to optimize data collection.
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Affiliation(s)
- Patrick C Bonasso
- Department of Pediatric Surgery, University of Arkansas for Medical Sciences, Little Rock, USA.
| | - Melvin S Dassinger
- Department of Pediatric Surgery, University of Arkansas for Medical Sciences, Little Rock, USA
| | - Morten O Jensen
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, USA
| | - Samuel D Smith
- Department of Pediatric Surgery, University of Arkansas for Medical Sciences, Little Rock, USA
| | - Jeffrey M Burford
- Department of Pediatric Surgery, University of Arkansas for Medical Sciences, Little Rock, USA
| | - Kevin W Sexton
- Department of Surgery, University of Arkansas for Medical Sciences, Little Rock, USA
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12
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Jensen MO, Jensen H, Skov SN, Levine RA, Nygaard H, M Hasenkam J, Nielsen SL. New Mitral Valve Annuloplasty Concept: Optimizing Annular Dynamics and Force Distribution. J Heart Valve Dis 2018; 27:38-46. [PMID: 30560598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
BACKGROUND Temporal three-dimensional (3D) analysis of the mitral valve biomechanics has prompted a re-evaluation of surgical approaches and repair device designs to accommodate the natural dynamics of the valve. Such new designs strive to obtain lower annulus restraining forces, resulting in more natural leaflet and chordal stresses. A new annuloplasty system was evaluated using 3D motion and out-of-plane force analysis. It was hypothesized that this system would not impact the valve with adverse motion restrictions or high systolic annular forces compared to conventional flat rigid ring designs. METHODS In an acute porcine set-up, six 80 kg pigs were monitored before and after implantation of the new annuloplasty system consisting of two half-rings with a saddle-shaped outline. Valvular 3D dynamic geometry was obtained using sonomicrometry before and after annuloplasty system implantation. Strain gauges mounted on the commissural segments provided the annular restraining force distribution perpendicular to the annular plane. RESULTS The change in annular height to commissural width ratio from diastole to systole did not alter following implantation (p >0.05). Out-of-plane systolic restraining forces were 0.2 ± 0.1 N and 0.8 ± 0.3 N (mean ± SEM) in the posterior and anterior commissural segments, respectively, without any difference in-between (p >0.1). Forces in both commissural segments were significantly lowered compared to previous measurements with a flat and stiff mitral annuloplasty ring (p <0.01). Mitral annular septal-lateral distance, area, and circumference in the commissural segments were decreased after implantation (p <0.05). The cross-annular distance between the commissural segments and the lengths of the anterior and posterior annular segments did not change following implantation (p >0.05). CONCLUSIONS The new annuloplasty system design maintained annular 3D dynamics and provided a minimized out-of-plane restraining force distribution compared to earlier studies on flat rigid rings. This may have important implications in the selection of annuloplasty devices in order to increase repair durability.
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Affiliation(s)
- Morten O Jensen
- Department. of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Aarhus, Denmark
- Department. of Biomedical Engineering, University of Arkansas, Fayetteville, Arkansas, USA. Electronic correspondence:
| | - Henrik Jensen
- Department. of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Aarhus, Denmark
| | - Søren N Skov
- Department. of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Aarhus, Denmark
| | - Robert A Levine
- Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Hans Nygaard
- Department. of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Aarhus, Denmark
| | - J M Hasenkam
- Department. of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Aarhus, Denmark
| | - Sten L Nielsen
- Department. of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Aarhus, Denmark
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Stephens SE, Liachenko S, Ingels NB, Wenk JF, Jensen MO. High resolution imaging of the mitral valve in the natural state with 7 Tesla MRI. PLoS One 2017; 12:e0184042. [PMID: 28854273 PMCID: PMC5576658 DOI: 10.1371/journal.pone.0184042] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2017] [Accepted: 08/16/2017] [Indexed: 11/20/2022] Open
Abstract
Imaging techniques of the mitral valve have improved tremendously during the last decade, but challenges persist. The delicate changes in annulus shape and papillary muscle position throughout the cardiac cycle have significant impact on the stress distribution in the leaflets and chords, thus preservation of anatomically accurate positioning is critical. The aim of this study was to develop an in vitro method and apparatus for obtaining high-resolution 3D MRI images of porcine mitral valves in both the diastolic and systolic configurations with physiologically appropriate annular shape, papillary muscle positions and orientations, specific to the heart from which the valve was harvested. Positioning and mounting was achieved through novel, customized mounting hardware consisting of papillary muscle and annulus holders with geometries determined via pre-mortem ultrasonic intra-valve measurements. A semi-automatic process was developed and employed to tailor Computer Aided Design models of the holders used to mount the valve. All valve mounting hardware was 3D printed using a stereolithographic printer, and the material of all fasteners used were brass for MRI compatibility. The mounted valves were placed within a clear acrylic case, capable of holding a zero-pressure and pressurized liquid bath of a MRI-compatible fluid. Obtaining images from the valve submerged in liquid fluid mimics the natural environment surrounding the valve, avoiding artefacts due to tissue surface tension mismatch and gravitational impact on tissue shape when not neutrally buoyant. Fluid pressure was supplied by reservoirs held at differing elevations and monitored and controlled to within ±1mmHg to ensure that the valves remained steady. The valves were scanned in a 7 Tesla MRI system providing a voxel resolution of at least 80μm. The systematic approach produced 3D datasets of high quality which, when combined with physiologically accurate positioning by the apparatus, can serve as an important input for validated computational models.
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Affiliation(s)
- Sam E. Stephens
- Department of Mechanical Engineering, University of Arkansas, Fayetteville, Arkansas, United States of America
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, Arkansas, United States of America
| | - Serguei Liachenko
- Division of Neurotoxicology, National Center for Toxicological Research, US Food and Drug Administration, Jefferson, Arkansas, United States of America
| | - Neil B. Ingels
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, Arkansas, United States of America
| | - Jonathan F. Wenk
- Department of Mechanical Engineering, University of Kentucky, Lexington, Kentucky, United States of America
| | - Morten O. Jensen
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, Arkansas, United States of America
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14
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Skov SN, Røpcke DM, Tjørnild MJ, Ilkjær C, Rasmussen J, Nygaard H, M Hasenkam J, Jensen MO, Nielsen SL. Remodeling Mitral Annuloplasty Ring Concept with Preserved Dynamics of Annular Height. J Heart Valve Dis 2017; 26:295-303. [PMID: 29092114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
BACKGROUND AND AIM OF THE STUDY The configuration of the native annulus changes from nearly flat in the diastolic phase to saddle-shaped in the systolic phase. The present study was conducted to test a novel remodeling annuloplasty ring with built-in septal-lateral fixation and commissural axial flexibility so as to maintain the change in annular saddle shape. The study aim was to evaluate the in-vivo biomechanical performance of the novel annuloplasty ring, compared with the native valve and a semi-rigid and rigid annuloplasty ring. METHODS All measurements were performed in vivo using a porcine model. A total of 28 pigs (bodyweight ca. 80 kg) were randomized to four groups: (i) with no ring; (ii) with a novel remodeling ring; (iii) with a semi-rigid ring (Physio I Ring, Edwards Lifesciences); and (iv) with a rigid ring (Classic Annuloplasty Ring, Edwards Lifesciences). Force measurements were performed using a dedicated transducer to determine remodeling capacity of the annuloplasty rings. Geometric parameters were measured by implanting sonomicrometry crystals along the mitral annulus. RESULTS All ring groups significantly restricted the cyclic change of the mitral annulus compared with the 'no-ring' group. The change and maximum value of the annular height were maintained for the novel ring but were significantly decreased for the rigid and semi-rigid rings compared with the 'no-ring' group. Mitral annular force measurements confirmed that the overall remodeling capacity of the novel ring was comparable with the conventional ring groups, and significantly higher in the septal-lateral direction compared to the semi-rigid ring. CONCLUSIONS In-vivo geometry and force measurements indicated that the intended design features of the new device were successfully provided. The novel ring concept with remodeling properties, combined with the advantages of a flexible annuloplasty ring, is unique. The maintenance of annular saddle shape and cyclic change in annular height may be an important step towards improved mitral valve repair.
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Affiliation(s)
- Søren N Skov
- Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Aarhus, Denmark
- Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark. Electrnic correspondence:
| | - Diana M Røpcke
- Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Aarhus, Denmark
- Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark
| | - Marcell J Tjørnild
- Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Aarhus, Denmark
- Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark
| | - Christine Ilkjær
- Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Aarhus, Denmark
- Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark
| | - Jonas Rasmussen
- Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Aarhus, Denmark
- Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark
| | - Hans Nygaard
- Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Aarhus, Denmark
- Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark
| | - J M Hasenkam
- Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Aarhus, Denmark
- Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark
| | - Morten O Jensen
- Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Aarhus, Denmark
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR, USA
| | - Sten L Nielsen
- Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Aarhus, Denmark
- Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark
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Bloodworth CH, Pierce EL, Easley TF, Drach A, Khalighi AH, Toma M, Jensen MO, Sacks MS, Yoganathan AP. Ex Vivo Methods for Informing Computational Models of the Mitral Valve. Ann Biomed Eng 2017; 45:496-507. [PMID: 27699507 PMCID: PMC5300906 DOI: 10.1007/s10439-016-1734-z] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 09/12/2016] [Indexed: 11/28/2022]
Abstract
Computational modeling of the mitral valve (MV) has potential applications for determining optimal MV repair techniques and risk of recurrent mitral regurgitation. Two key concerns for informing these models are (1) sensitivity of model performance to the accuracy of the input geometry, and, (2) acquisition of comprehensive data sets against which the simulation can be validated across clinically relevant geometries. Addressing the first concern, ex vivo micro-computed tomography (microCT) was used to image MVs at high resolution (~40 micron voxel size). Because MVs distorted substantially during static imaging, glutaraldehyde fixation was used prior to microCT. After fixation, MV leaflet distortions were significantly smaller (p < 0.005), and detail of the chordal tree was appreciably greater. Addressing the second concern, a left heart simulator was designed to reproduce MV geometric perturbations seen in vivo in functional mitral regurgitation and after subsequent repair, and maintain compatibility with microCT. By permuting individual excised ovine MVs (n = 5) through each state (healthy, diseased and repaired), and imaging with microCT in each state, a comprehensive data set was produced. Using this data set, work is ongoing to construct and validate high-fidelity MV biomechanical models. These models will seek to link MV function across clinically relevant states.
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Affiliation(s)
- Charles H Bloodworth
- Cardiovascular Fluid Mechanics Laboratory, Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, 387 Technology Circle NW, Suite 200, Atlanta, GA, 30313, USA
| | - Eric L Pierce
- Cardiovascular Fluid Mechanics Laboratory, Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, 387 Technology Circle NW, Suite 200, Atlanta, GA, 30313, USA
| | - Thomas F Easley
- Cardiovascular Fluid Mechanics Laboratory, Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, 387 Technology Circle NW, Suite 200, Atlanta, GA, 30313, USA
| | - Andrew Drach
- Center for Cardiovascular Simulation, Institute for Computational Engineering and Sciences, The University of Texas at Austin, 201 E. 24th Street, Austin, TX, 78712, USA
| | - Amir H Khalighi
- Center for Cardiovascular Simulation, Institute for Computational Engineering and Sciences, The University of Texas at Austin, 201 E. 24th Street, Austin, TX, 78712, USA
| | - Milan Toma
- Cardiovascular Fluid Mechanics Laboratory, Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, 387 Technology Circle NW, Suite 200, Atlanta, GA, 30313, USA
| | - Morten O Jensen
- Cardiovascular Fluid Mechanics Laboratory, Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, 387 Technology Circle NW, Suite 200, Atlanta, GA, 30313, USA
| | - Michael S Sacks
- Center for Cardiovascular Simulation, Institute for Computational Engineering and Sciences, The University of Texas at Austin, 201 E. 24th Street, Austin, TX, 78712, USA
| | - Ajit P Yoganathan
- Cardiovascular Fluid Mechanics Laboratory, Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, 387 Technology Circle NW, Suite 200, Atlanta, GA, 30313, USA.
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16
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Grbic S, Easley TF, Mansi T, Bloodworth CH, Pierce EL, Voigt I, Neumann D, Krebs J, Yuh DD, Jensen MO, Comaniciu D, Yoganathan AP. Personalized mitral valve closure computation and uncertainty analysis from 3D echocardiography. Med Image Anal 2017; 35:238-249. [DOI: 10.1016/j.media.2016.03.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Revised: 03/22/2016] [Accepted: 03/30/2016] [Indexed: 10/21/2022]
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Pantoja JL, Morgan AE, Grossi EA, Jensen MO, Weinsaft JW, Levine RA, Ge L, Ratcliffe MB. Undersized Mitral Annuloplasty Increases Strain in the Proximal Lateral Left Ventricular Wall. Ann Thorac Surg 2016; 103:820-827. [PMID: 27720201 DOI: 10.1016/j.athoracsur.2016.07.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 06/10/2016] [Accepted: 07/05/2016] [Indexed: 10/20/2022]
Abstract
BACKGROUND Recurrence of mitral regurgitation (MR) after undersized mitral annuloplasty (MA) for ischemic MR is as high as 60%, with the recurrence rate likely due to continued dilation of the left ventricle (LV). To better understand the causes of recurrent MR, we studied the effect of undersized MA on strain in the LV wall. We hypothesize that the acute change in ventricular shape induced by MA will cause increased strain in regions nearest the mitral valve. METHODS Finite element models were previously reported, based on cardiac magnetic resonance images of 5 sheep with mild to moderate ischemic MR. A 24-mm saddle-shaped rigid annuloplasty ring was modeled and used to simulate virtual MA. Longitudinal and myofiber strains were calculated at end-diastole and end-systole, with preoperative early diastolic geometry as the reference state. RESULTS The undersized MA significantly increased longitudinal strain at end-diastole in the lateral LV wall. The effect was greatest in the proximal-lateral endocardial surface, where longitudinal strain after MA was approximately triple the preoperative strain (11.17% ± 2.15% vs 3.45% ± 0.92%, p = 0.0057). In contrast, postoperative end-diastolic fiber strain decreased in this same region (2.53% ± 2.14% vs 7.72% ± 1.79%, p = 0.0060). There were no significant changes in either strain type at end-systole. CONCLUSIONS Undersized MA increased longitudinal strain in the proximal lateral LV wall at end-diastole. This procedure-related strain at the proximal-lateral LV wall may foster continued LV enlargement and subsequent recurrence of mitral regurgitation.
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Affiliation(s)
- Joe Luis Pantoja
- University of California, San Francisco, San Francisco, California
| | - Ashley E Morgan
- East Bay Surgical Residency, University of California, San Francisco, San Francisco, California
| | - Eugene A Grossi
- Department of Cardiothoracic Surgery, New York University, New York, New York; New York Harbor Veterans Affairs Medical Center, New York, New York
| | - Morten O Jensen
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, Arkansas
| | - Jonathan W Weinsaft
- Departments of Medicine (Cardiology) and Radiology, Weill Cornell Medicine, New York, New York
| | - Robert A Levine
- Division of Cardiology, Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts
| | - Liang Ge
- Department of Surgery, University of California, San Francisco, San Francisco, California; Department of Bioengineering, University of California, San Francisco, San Francisco, California; Veterans Affairs Medical Center, San Francisco, California
| | - Mark B Ratcliffe
- Department of Surgery, University of California, San Francisco, San Francisco, California; Veterans Affairs Medical Center, San Francisco, California.
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Pierce EL, Rabbah JPM, Thiele K, Wei Q, Vidakovic B, Jensen MO, Hung J, Yoganathan AP. Three-Dimensional Field Optimization Method: Gold-Standard Validation of a Novel Color Doppler Method for Quantifying Mitral Regurgitation. J Am Soc Echocardiogr 2016; 29:917-925. [PMID: 27354250 DOI: 10.1016/j.echo.2016.05.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Indexed: 11/29/2022]
Abstract
BACKGROUND Accurate diagnosis of mitral regurgitation (MR) severity is central to proper treatment. Although numerous approaches exist, an accurate, gold-standard clinical technique remains elusive. The authors previously reported on the initial development and demonstration of the automated three-dimensional (3D) field optimization method (FOM) algorithm, which exploits 3D color Doppler ultrasound imaging and builds on existing MR quantification techniques. The aim of the present study was to extensively validate 3D FOM in terms of accuracy, ease of use, and repeatability. METHODS Three-dimensional FOM was applied to five explanted ovine mitral valves in a left heart simulator, which were systematically perturbed to yield a total of 29 unique regurgitant geometries. Three-dimensional FOM was compared with a gold-standard flow probe, as well as the most clinically prevalent MR volume quantification technique, the two-dimensional (2D) proximal isovelocity surface area (PISA) method. RESULTS Overall, 3D FOM overestimated and 2D PISA underestimated MR volume, but 3D FOM error had smaller magnitude (5.2 ± 9.9 mL) than 2D PISA error (-6.9 ± 7.7 mL). Two-dimensional PISA remained superior in diagnosis for round orifices and especially mild MR, as predicted by ultrasound physics theory. For slit-type orifices and severe MR, 3D FOM showed significant improvement over 2D PISA. Three-dimensional FOM processing was technically simpler and significantly faster than 2D PISA and required fewer ultrasound acquisitions. Three-dimensional FOM did not show significant interuser variability, whereas 2D PISA did. CONCLUSIONS Three-dimensional FOM may provide increased clinical value compared with 2D PISA because of increased accuracy in the case of complex or severe regurgitant orifices as well as its greater repeatability and simpler work flow.
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Affiliation(s)
- Eric L Pierce
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia
| | - Jean Pierre M Rabbah
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia
| | | | - Qifeng Wei
- Philips Health Tech, Andover, Massachusetts
| | - Brani Vidakovic
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia
| | - Morten O Jensen
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia
| | - Judy Hung
- Echocardiography Laboratory of the Massachusetts General Hospital, Boston, Massachusetts
| | - Ajit P Yoganathan
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia.
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Pierce EL, Siefert AW, Paul DM, Wells SK, Bloodworth CH, Takebayashi S, Aoki C, Jensen MO, Gillespie MJ, Gorman RC, Gorman JH, Yoganathan AP. How Local Annular Force and Collagen Density Govern Mitral Annuloplasty Ring Dehiscence Risk. Ann Thorac Surg 2016; 102:518-26. [PMID: 27133454 DOI: 10.1016/j.athoracsur.2016.01.107] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2015] [Revised: 11/28/2015] [Accepted: 01/28/2016] [Indexed: 10/21/2022]
Abstract
BACKGROUND Annuloplasty ring dehiscence is a well described mode of mitral valve repair failure. Defining the mechanisms underlying dehiscence may facilitate its prevention. METHODS Factors that govern suture dehiscence were examined with an ovine model. After undersized ring annuloplasty in live animals (n = 5), cyclic force (FC) that acts on sutures during cardiac contraction was measured with custom transducers. FC was measured at ten suture positions, throughout cardiac cycles with peak left ventricular pressure (LVPmax) of 100, 125, and 150 mm Hg. Suture pullout testing was conducted on explanted mitral annuli (n = 12) to determine suture holding strength at each position. Finally, relative collagen density differences at suture sites around the annulus were assessed by two-photon excitation fluoroscopy. RESULTS Anterior FC exceeded posterior FC at each LVPmax (eg, 2.8 ± 1.3 N versus 1.8 ± 1.2 N at LVPmax = 125 mm Hg, p < 0.01). Anterior holding strength exceeded posterior holding strength (6.4 ± 3.6 N versus 3.9 ± 1.6 N, p < 0.0001). On the basis of FC at LVPmax of 150 mm Hg, margin of safety before suture pullout was vastly higher between the trigones (exclusive) versus elsewhere (4.8 ± 0.9 N versus 1.9 ± 0.5 N, p < 0.001). Margin of safety exhibited strong correlation to collagen density (R(2) = 0.947). CONCLUSIONS Despite lower cyclic loading on posterior sutures, the weaker posterior mitral annular tissue creates higher risk of dehiscence, apparently because of reduced collagen content. Sutures placed atop the trigones are less secure than predicted, because of a combination of reduced collagen and higher overall rigidity in this region. These findings highlight the inter-trigonal tissue as the superior anchor and have implications on the design and implantation techniques for next-generation mitral prostheses.
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Affiliation(s)
- Eric L Pierce
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia
| | - Andrew W Siefert
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia
| | - Deborah M Paul
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia
| | - Sarah K Wells
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia
| | - Charles H Bloodworth
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia
| | - Satoshi Takebayashi
- Gorman Cardiovascular Research Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Chikashi Aoki
- Gorman Cardiovascular Research Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Morten O Jensen
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia
| | - Matthew J Gillespie
- Gorman Cardiovascular Research Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Cardiology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Robert C Gorman
- Gorman Cardiovascular Research Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Joseph H Gorman
- Gorman Cardiovascular Research Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Ajit P Yoganathan
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia.
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Pierce EL, Bloodworth CH, Naran A, Easley TF, Jensen MO, Yoganathan AP. Novel Method to Track Soft Tissue Deformation by Micro-Computed Tomography: Application to the Mitral Valve. Ann Biomed Eng 2015; 44:2273-81. [PMID: 26553575 DOI: 10.1007/s10439-015-1499-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 10/31/2015] [Indexed: 11/29/2022]
Abstract
Increasing availability of micro-computed tomography (µCT) as a structural imaging gold-standard is bringing unprecedented geometric detail to soft tissue modeling. However, the utility of these advances is severely hindered without analogous enhancement to the associated kinematic detail. To this end, labeling and following discrete points on a tissue across various deformation states is a well-established approach. Still, existing techniques suffer limitations when applied to complex geometries and large deformations and strains. Therefore, we herein developed a non-destructive system for applying fiducial markers (minimum diameter: 500 µm) to soft tissue and tracking them through multiple loading conditions by µCT. Using a novel applicator to minimize adhesive usage, four distinct marker materials were resolvable from both tissue and one another, without image artifacts. No impact on tissue stiffness was observed. µCT addressed accuracy limitations of stereophotogrammetry (inter-method positional error 1.2 ± 0.3 mm, given marker diameter 1.9 ± 0.1 mm). Marker application to ovine mitral valves revealed leaflet Almansi areal strains (45 ± 4%) closely matching literature values, and provided radiographic access to previously inaccessible regions, such as the leaflet coaptation zone. This system may meaningfully support mechanical characterization of numerous tissues or biomaterials, as well as tissue-device interaction studies for regulatory standards purposes.
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Affiliation(s)
- Eric L Pierce
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, 387 Technology Circle NW, Suite 200, Atlanta, GA, 30313, USA
| | - Charles H Bloodworth
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, 387 Technology Circle NW, Suite 200, Atlanta, GA, 30313, USA
| | - Ajay Naran
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, 387 Technology Circle NW, Suite 200, Atlanta, GA, 30313, USA
| | - Thomas F Easley
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, 387 Technology Circle NW, Suite 200, Atlanta, GA, 30313, USA
| | - Morten O Jensen
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, 387 Technology Circle NW, Suite 200, Atlanta, GA, 30313, USA
| | - Ajit P Yoganathan
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, 387 Technology Circle NW, Suite 200, Atlanta, GA, 30313, USA.
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Levine RA, Hagége AA, Judge DP, Padala M, Dal-Bianco JP, Aikawa E, Beaudoin J, Bischoff J, Bouatia-Naji N, Bruneval P, Butcher JT, Carpentier A, Chaput M, Chester AH, Clusel C, Delling FN, Dietz HC, Dina C, Durst R, Fernandez-Friera L, Handschumacher MD, Jensen MO, Jeunemaitre XP, Le Marec H, Le Tourneau T, Markwald RR, Mérot J, Messas E, Milan DP, Neri T, Norris RA, Peal D, Perrocheau M, Probst V, Pucéat M, Rosenthal N, Solis J, Schott JJ, Schwammenthal E, Slaugenhaupt SA, Song JK, Yacoub MH. Mitral valve disease--morphology and mechanisms. Nat Rev Cardiol 2015; 12:689-710. [PMID: 26483167 DOI: 10.1038/nrcardio.2015.161] [Citation(s) in RCA: 222] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Mitral valve disease is a frequent cause of heart failure and death. Emerging evidence indicates that the mitral valve is not a passive structure, but--even in adult life--remains dynamic and accessible for treatment. This concept motivates efforts to reduce the clinical progression of mitral valve disease through early detection and modification of underlying mechanisms. Discoveries of genetic mutations causing mitral valve elongation and prolapse have revealed that growth factor signalling and cell migration pathways are regulated by structural molecules in ways that can be modified to limit progression from developmental defects to valve degeneration with clinical complications. Mitral valve enlargement can determine left ventricular outflow tract obstruction in hypertrophic cardiomyopathy, and might be stimulated by potentially modifiable biological valvular-ventricular interactions. Mitral valve plasticity also allows adaptive growth in response to ventricular remodelling. However, adverse cellular and mechanobiological processes create relative leaflet deficiency in the ischaemic setting, leading to mitral regurgitation with increased heart failure and mortality. Our approach, which bridges clinicians and basic scientists, enables the correlation of observed disease with cellular and molecular mechanisms, leading to the discovery of new opportunities for improving the natural history of mitral valve disease.
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Affiliation(s)
- Robert A Levine
- Cardiac Ultrasound Laboratory, Massachusetts General Hospital, Harvard Medical School, 55 Fruit Street, Yawkey 5E, Boston, MA 02114, USA
| | - Albert A Hagége
- Hôpital Européen Georges Pompidou, Université René Descartes, UMR 970, Paris, France
| | | | | | - Jacob P Dal-Bianco
- Massachusetts General Hospital, Cardiac Ultrasound Laboratory, Harvard Medical School, Boston, MA, USA
| | | | | | | | - Nabila Bouatia-Naji
- Hôpital Européen Georges Pompidou, Université René Descartes, UMR 970, Paris, France
| | - Patrick Bruneval
- Hôpital Européen Georges Pompidou, Université René Descartes, UMR 970, Paris, France
| | | | - Alain Carpentier
- Hôpital Européen Georges Pompidou, Université René Descartes, UMR 970, Paris, France
| | | | | | | | - Francesca N Delling
- Beth Israel Deaconess Medical Centre, Harvard Medical School, Boston, MA, USA
| | | | - Christian Dina
- University of Nantes, Thoracic Institute, INSERM UMR 1097, CNRS UMR 6291, Nantes, France
| | - Ronen Durst
- Hadassah-Hebrew University Medical Centre, Jerusalem, Israel
| | - Leticia Fernandez-Friera
- Hospital Universitario HM Monteprincipe and the Centro Nacional de Investigaciones Cardiovasculares, Carlos III (CNIC), Madrid, Spain
| | - Mark D Handschumacher
- Massachusetts General Hospital, Cardiac Ultrasound Laboratory, Harvard Medical School, Boston, MA, USA
| | | | - Xavier P Jeunemaitre
- Hôpital Européen Georges Pompidou, Université René Descartes, UMR 970, Paris, France
| | - Hervé Le Marec
- University of Nantes, Thoracic Institute, INSERM UMR 1097, CNRS UMR 6291, Nantes, France
| | - Thierry Le Tourneau
- University of Nantes, Thoracic Institute, INSERM UMR 1097, CNRS UMR 6291, Nantes, France
| | | | - Jean Mérot
- University of Nantes, Thoracic Institute, INSERM UMR 1097, CNRS UMR 6291, Nantes, France
| | - Emmanuel Messas
- Hôpital Européen Georges Pompidou, Université René Descartes, UMR 970, Paris, France
| | - David P Milan
- Cardiovascular Research Center, Harvard Medical School, Boston, MA, USA
| | - Tui Neri
- Aix-Marseille University, INSERM UMR 910, Marseille, France
| | | | - David Peal
- Cardiovascular Research Center, Harvard Medical School, Boston, MA, USA
| | - Maelle Perrocheau
- Hôpital Européen Georges Pompidou, Université René Descartes, UMR 970, Paris, France
| | - Vincent Probst
- University of Nantes, Thoracic Institute, INSERM UMR 1097, CNRS UMR 6291, Nantes, France
| | - Michael Pucéat
- Aix-Marseille University, INSERM UMR 910, Marseille, France
| | | | - Jorge Solis
- Hospital Universitario HM Monteprincipe and the Centro Nacional de Investigaciones Cardiovasculares, Carlos III (CNIC), Madrid, Spain
| | - Jean-Jacques Schott
- University of Nantes, Thoracic Institute, INSERM UMR 1097, CNRS UMR 6291, Nantes, France
| | | | - Susan A Slaugenhaupt
- Center for Human Genetic Research, MGH Research Institute, Harvard Medical School, Boston, MA, USA
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Drach A, Khalighi AH, ter Huurne FM, Lee CH, Bloodworth C, Pierce EL, Jensen MO, Yoganathan AP, Sacks MS. Population-Averaged Geometric Model of Mitral Valve From Patient-Specific Imaging Data1. J Med Device 2015. [DOI: 10.1115/1.4030582] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Andrew Drach
- Center for Cardiovascular Simulation, Institute for Computational Engineering and Sciences, The University of Texas at Austin, Austin, TX 78712
| | - Amir H. Khalighi
- Center for Cardiovascular Simulation, Institute for Computational Engineering and Sciences, The University of Texas at Austin, Austin, TX 78712
- Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX 78712
| | - Fleur M. ter Huurne
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven 5600 MB, The Netherlands
| | - Chung-Hao Lee
- Center for Cardiovascular Simulation, Institute for Computational Engineering and Sciences, The University of Texas at Austin, Austin, TX 78712
| | - Charles Bloodworth
- Cardiovascular Fluid Mechanics Laboratory, Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30318
| | - Eric L. Pierce
- Cardiovascular Fluid Mechanics Laboratory, Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30318
| | - Morten O. Jensen
- Cardiovascular Fluid Mechanics Laboratory, Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30318
| | - Ajit P. Yoganathan
- Cardiovascular Fluid Mechanics Laboratory, Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30318
| | - Michael S. Sacks
- Center for Cardiovascular Simulation, Institute for Computational Engineering and Sciences, The University of Texas at Austin, Austin, TX 78712
- Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX 78712
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712
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Skov SN, Røpcke DM, Telling K, Ilkjær C, Tjørnild MJ, Nygaard H, Nielsen SL, Jensen MO. Simultaneous in- and out-of-plane Mitral Valve Annular Force Measurements. Cardiovasc Eng Technol 2015; 6:185-92. [DOI: 10.1007/s13239-015-0227-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2014] [Accepted: 04/22/2015] [Indexed: 10/23/2022]
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Jensen H, Jensen MO, Nielsen SL. Surgical Treatment of Functional Ischemic Mitral Regurgitation. J Heart Valve Dis 2015; 24:30-42. [PMID: 26182617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
After myocardial infarction, functional ischemic mitral regurgitation (FIMR) is present in 21% of patients, and 3-13% have at least moderate FIMR. Currently, the 'gold-standard' treatment of FIMR is down-sized ring annuloplasty at the time of coronary artery bypass (CABG) surgery. However, this procedure has a failure rate of 20-30% in terms of recurrent FIMR after two to four years. In many ways, a cross-roads has been reached in terms of what constitutes optimal FIMR treatment: Is CABG combined with mitral valve ring annuloplasty better than CABG alone in moderate FIMR? Does mitral valve repair really produce better outcome than mitral valve replacement? And does adding an adjunct valvular repair or subvalvular left ventricular reverse remodeling procedure shift that balance? In order to shed further light on these questions and to help identify potential cornerstones in improving the 'gold standard' therapy, the present review addresses the current status and future perspectives of the surgical treatment of FIMR.
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Jensen MO, Honge JL, Benediktsson JA, Siefert AW, Jensen H, Yoganathan AP, Snow TK, Hasenkam JM, Nygaard H, Nielsen SL. Mitral valve annular downsizing forces: Implications for annuloplasty device development. J Thorac Cardiovasc Surg 2014; 148:83-9. [DOI: 10.1016/j.jtcvs.2013.07.045] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Revised: 06/26/2013] [Accepted: 07/12/2013] [Indexed: 11/30/2022]
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Jensen H, Jensen MO, Vind-Kezunovic S, Vestergaard R, Ringgaard S, Smerup MH, Hønge JL, Hasenkam JM, Nielsen SL. Surgical relocation of the papillary muscles in functional ischemic mitral regurgitation: what are the forces of the relocation stitches acting on the myocardium? J Heart Valve Dis 2013; 22:524-531. [PMID: 24224415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
BACKGROUND AND AIM OF THE STUDY In patients with chronic functional ischemic mitral regurgitation (FIMR), papillary muscle relocation has the potential to induce reverse left ventricular remodeling. However, in order to optimize function and durability, the forces imposed on the left ventricular myocardium by papillary muscle relocation should be assessed. METHODS Eight pigs with FIMR were subjected to down-sized ring annuloplasty in combination with relocation of the anterior (5 mm) and posterior (15 mm) papillary muscles towards the respective trigone. Papillary muscle relocation was obtained by a 2-0 expanded polytetrafluoroethylene stitch fixed to the trigone, exteriorized through the myocardium overlying the papillary muscle, and fixed to an epicardial disc. Tension in these stitches was measured at a systolic blood pressure > 80 mmHg using a custom-made sliding caliper with a strain gauge mounted in line. This allowed assessment of the cyclic change from minimal diastolic to maximum systolic papillary muscle relocation stitch tension. RESULTS Maximum cyclic change in the posterior papillary muscle (PPM) stitch tension was 1.1 N at 15 mm relocation. In comparison, the anterior papillary muscle (APM) tension was increased to a maximum of 1.4 N with only 5 mm relocation. Surprisingly, during each step of isolated PPM relocation, the APM stitch tension increased concomitantly, but in contrast APM relocation did not influence the magnitude of PPM stitch tension. There was no statistically significant difference between cyclic changes in APM and PPM stitch tension at any step of relocation. CONCLUSION Papillary muscle relocation using stitches attached between epicardial discs and respective trigones induced a cyclic change in papillary muscle relocation stitch tension of 1.1-1.4 N. These values were in the range of normal tension in the mitral valve apparatus, and equivalent to only 19-24% of the total papillary muscle forces. Therefore, this technique does not appear to induce a non-physiologically high cyclic load on the mitral valve complex.
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Affiliation(s)
- Henrik Jensen
- Department of Cardiothoracic and Vascular Surgery T, Aarhus University Hospital-Skejby, Denmark.
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Askov JB, Honge JL, Jensen MO, Nygaard H, Hasenkam JM, Nielsen SL. Significance of force transfer in mitral valve–left ventricular interaction: In vivo assessment. J Thorac Cardiovasc Surg 2013; 145:1635-41, 1641.e1. [DOI: 10.1016/j.jtcvs.2012.07.062] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Revised: 07/10/2012] [Accepted: 07/26/2012] [Indexed: 11/26/2022]
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Røpcke DM, Hjortdal VE, Toft GE, Jensen MO, Kristensen SD. Remote ischemic preconditioning reduces thrombus formation in the rat. J Thromb Haemost 2013. [DOI: 10.1111/j.1538-7836.2013.04914.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
| | - VE Hjortdal
- Department of Cardiothoracic Surgery; Aarhus University Hospital - Skejby; Brendstrupgaardsvej 100; 8200; Aarhus N; DK
| | - GE Toft
- Department of Plastic Surgery; Aarhus University Hospital - NBG; Nørrebrogade 44; 8000; Aarhus C; DK
| | - MO Jensen
- Department of Engineering; University of Aarhus; Dalgas Avenue 2; 8000; Aarhus C; DK
| | - SD Kristensen
- Department of Cardiology; Aarhus University Hospital - Skejby; Brendstrupgaardsvej 100; 8200; Aarhus N; DK
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Rahmani A, Rasmussen AQ, Honge JL, Ostli B, Levine RA, Hagège A, Nygaard H, Nielsen SL, Jensen MO. Mitral valve mechanics following posterior leaflet patch augmentation. J Heart Valve Dis 2013; 22:28-35. [PMID: 23610985 PMCID: PMC3644588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
BACKGROUND AND AIM OF THE STUDY Attention towards the optimization of mitral valve repair methods is increasing. Patch augmentation is one strategy used to treat functional ischemic mitral regurgitation (FIMR). The study aim was to investigate the force balance changes in specific chordae tendineae emanating from the posterior papillary muscle in a FIMR-simulated valve, following posterior leaflet patch augmentation. METHODS Mitral valves were obtained from 12 pigs (body weight 80 kg). An in vitro test set-up simulating the left ventricle was used to hold the valves. The left ventricular pressure was regulated with water to simulate different static pressures during valve closure. A standardized oval pericardial patch (17 x 29 mm) was introduced into the posterior leaflet from mid P2 to the end of the P3 scallop. Dedicated miniature transducers were used to record the forces exerted on the chordae tendineae. Data were acquired before and after 12 mm posterior and 5 mm apical posterior papillary muscle displacement to simulate the effect from one of the main contributors of FIMR, before and after patch augmentation. RESULTS The effect of displacing the posterior papillary muscle induced tethering on the intermediate chordae tendineae to the posterior leaflet, and resulted in a 39.8% force increase (p = 0.014). Posterior leaflet patch augmentation of the FIMR valve induced a 31.1% force decrease (p = 0.007). There was no difference in force between the healthy and the repaired valve simulations (p = 0.773). CONCLUSION Posterior leaflet patch augmentation significantly reduced the forces exerted on the intermediate chordae tendineae from the posterior papillary muscle following FIMR simulation. As changes in chordal tension lead to a redistribution of the total stress exerted on the valve, patch augmentation may have an adverse long-term influence on mitral valve function and remodeling.
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Affiliation(s)
- Azadeh Rahmani
- Department of Engineering, University of Aarhus, Aarhus, Denmark
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Affiliation(s)
- D M Røpcke
- Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital - Skejby Department of Experimental and Clinical Research, Aarhus University Hospital - Skejby Department of Plastic Surgery, Aarhus University Hospital - NBG Department of Engineering, University of Aarhus Department of Cardiology, Aarhus University Hospital - Skejby, Denmark
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Ostli B, Vester-Petersen J, Askov JB, Honge JL, Levine RA, Hagège A, Nielsen SL, Hasenkam JM, Nygaard H, Jensen MO. In Vitro System for Measuring Chordal Force Changes Following Mitral Valve Patch Repair. Cardiovasc Eng Technol 2012; 3:263-268. [PMID: 26273417 DOI: 10.1007/s13239-012-0098-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
BACKGROUND Attention towards optimization of mitral valve repair methods is increasing. Patch augmentation is one strategy utilized to correct functional mitral regurgitation or systolic anterior motion in complex mitral valve repairs. This article describes a system for investigating the redistribution of chordae tendineae tension as a reflection of altered stress distribution of the valve leaflet following patch augmentation. METHODS AND MATERIALS An in vitro test setup was constructed to hold native porcine mitral valves containing an annulus and papillary muscle positioning system. The alterations caused by patch augmentation should be visual from both the atrial and ventricular views. Ventricular pressure was regulated stepwise in a range of 0-150 mmHg. To test the system, the anterior mitral leaflet was extended by a pericardial patch sutured to the mid/basal part of the leaflet, and the chordae tendineae force was measured as the ventricular pressure was applied. RESULTS The system demonstrated the capacity to hold native porcine mitral valves and introducing patch repairs according to clinical practice. The porcine mitral valve test setup indicated strong correlation between the forces in the mitral valve secondary chordae tendineae and the applied transvalvular pressure (R2 = 0.95). CONCLUSION This test setup proved the ability to obtain normal mid-systolic mitral valve function, secondary chordae force measurements, and important preservation of the visual access: Hence, obtaining the pressure-force relationship as well as identifying any shift of the secondary chordae insertion point on the anterior leaflet relative to the coaptation zone was made possible.
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Affiliation(s)
- B Ostli
- Dept. of Biomedical Engineering, Engineering College of Aarhus, Aarhus, Denmark
| | - J Vester-Petersen
- Dept. of Biomedical Engineering, Engineering College of Aarhus, Aarhus, Denmark
| | - J B Askov
- Dept. of Biomedical Engineering, Engineering College of Aarhus, Aarhus, Denmark ; Dept. of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Skejby, Aarhus, Denmark
| | - J L Honge
- Dept. of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Skejby, Aarhus, Denmark
| | - R A Levine
- Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - A Hagège
- Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Department of Cardiology; University Paris Descartes; INSERM U 633; Paris, France
| | - S L Nielsen
- Dept. of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Skejby, Aarhus, Denmark
| | - J M Hasenkam
- Dept. of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Skejby, Aarhus, Denmark
| | - H Nygaard
- Dept. of Biomedical Engineering, Engineering College of Aarhus, Aarhus, Denmark ; Dept. of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Skejby, Aarhus, Denmark
| | - M O Jensen
- Dept. of Biomedical Engineering, Engineering College of Aarhus, Aarhus, Denmark ; Dept. of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Skejby, Aarhus, Denmark
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Jensen MO, Jensen H, Langhoff Honge J, Hans N, Hasenkam JM, Nielsen SL. External approach to in vivo force measurement on mitral valve traction suture. J Biomech 2012; 45:908-12. [DOI: 10.1016/j.jbiomech.2011.11.034] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/02/2011] [Indexed: 10/14/2022]
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Granier M, Jensen MO, Honge JL, Bel A, Menasché P, Nielsen SL, Carpentier A, Levine RA, Hagège AA. Consequences of mitral valve prolapse on chordal tension: ex vivo and in vivo studies in large animal models. J Thorac Cardiovasc Surg 2011; 142:1585-7. [PMID: 21955468 DOI: 10.1016/j.jtcvs.2011.08.035] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Revised: 08/15/2011] [Accepted: 08/25/2011] [Indexed: 11/25/2022]
Affiliation(s)
- Mathieu Granier
- Laboratory of Biosurgical Research, Foundation Alain Carpentier, Paris, France
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Jensen H, Jensen MO, Waziri F, Honge JL, Sloth E, Andersen NT, Wierup P, Hasenkam JM, Nielsen SL. IS TENSION ALTERATIONS OF TRANSAPICAL ARTIFICIAL CHORDAE TENDINEAE POTENTIALLY DETRIMENTAL FOR MITRAL REPAIR DURABILITY? J Am Coll Cardiol 2011. [DOI: 10.1016/s0735-1097(11)61385-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Jensen MO, Jensen H, Levine RA, Yoganathan AP, Andersen NT, Nygaard H, Hasenkam JM, Nielsen SL. Saddle-shaped mitral valve annuloplasty rings improve leaflet coaptation geometry. J Thorac Cardiovasc Surg 2011; 142:697-703. [PMID: 21329946 DOI: 10.1016/j.jtcvs.2011.01.022] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2010] [Revised: 12/17/2010] [Accepted: 01/10/2011] [Indexed: 10/18/2022]
Abstract
OBJECTIVES The mitral valve annulus naturally conforms to a saddle shape in systole. This configuration is believed to put the leaflets into a lower-energy equilibrium with the annulus and subvalvular apparatus. Conventional flat annuloplasty rings restrict posterior leaflet motion, which may result in a "monocusp" valve, affecting valvular stress distribution. It is hypothesized that saddle-shaped annuloplasty rings cause less distortion of the physiologic leaflet geometry than do flat rings. METHODS Twelve pigs were studied in an acute setting with 3-dimensional echocardiography and sonomicrometry before and after implantation of rigid flat (n = 5) and saddle-shaped (n = 7) annuloplasty rings. The rings were true sized to the annulus with equal anterior-posterior and commissure-commissure circumferential dimensions. The saddle-shaped rings had an annular height to commissural width ratio of 15%. RESULTS Saddle-shaped rings maintained both leaflets operational (P < .01). Flat rings made the posterior leaflet immobile and the anterior leaflet aligned flat along the annulus in systole, effectively resulting in monoleaflet function. The average distance from the papillary muscle tips to the posterior annulus decreased by 2.4 ± 0.4 mm after flat ring implantation (P < .01). CONCLUSIONS Saddle-shaped annuloplasty rings provide better leaflet coaptation geometry than do flat rings by not hoisting the papillary muscles toward the posterior annulus through the commissural chordae, allowing greater leaflet mobility. This entails a potentially beneficial impact on valvular stress distribution that could affect durability of the repaired valve.
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Affiliation(s)
- Morten O Jensen
- Department of Cardiothoracic and Vascular Surgery, Institute of Clinical Medicine, Aarhus University Hospital, Skejby, Aarhus, Denmark.
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Jensen H, Jensen MO, Smerup MH, Ringgaard S, Sørensen TS, Andersen NT, Wierup P, Hasenkam JM, Nielsen SL. Three-dimensional assessment of papillary muscle displacement in a porcine model of ischemic mitral regurgitation. J Thorac Cardiovasc Surg 2010; 140:1312-8. [DOI: 10.1016/j.jtcvs.2009.12.042] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2009] [Revised: 11/09/2009] [Accepted: 12/31/2009] [Indexed: 11/28/2022]
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Jensen H, Jensen MO, Smerup MH, Ringgaard S, Andersen NT, Wierup P, Hasenkam JM, Nielsen SL. Does down-sized ring annuloplasty induce papillary muscle relocation in ischemic mitral regurgitation? J Heart Valve Dis 2010; 19:692-700. [PMID: 21214091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
BACKGROUND AND AIM OF THE STUDY Down-sized ring annuloplasty has been shown to induce left ventricular remodeling in patients with functional ischemic mitral regurgitation (FIMR). To determine if this remodeling comprised papillary muscle (PM) relocation, a chronic FIMR porcine model was used to assess the impact on three-dimensional (3D) PM positioning, by implanting a down-sized rigid ring annuloplasty. METHODS Six out of ten FIMR pigs that underwent a down-sized mitral ring annuloplasty (CE Classic size 26-28) survived for six weeks postoperatively. 3D cardiac magnetic resonance imaging was carried out at one week preoperatively, and repeated at one and six weeks postoperatively, to assess the direct distances (in mm) from the anterior papillary muscle (APM) and posterior papillary muscle (PPM) to each trigone. Three reference planes were also constructed to determine APM and PPM displacement in the lateral, anterioposterior, and apical directions. RESULTS Relative to the preoperative situation, at one week postoperatively a reduced displacement of the APM was observed in an anterior direction (from 18.8 to 16.2 mm; p < 0.05) and from the posterior trigone (from 40.5 to 37.4 mm; p < 0.05) at end-diastole. Relative to one week postoperatively, at six weeks postoperatively a reduced PPM displacement was observed from the anterior trigone (43.0 versus 42.0 mm; p < 0.05) at end-systole. Relative to the preoperative situation, no overall tendency of surgically induced PM relocation was observed at one or six weeks postoperatively. CONCLUSION A down-sized ring annuloplasty did not induce an overall pattern of PM relocation in pigs with chronic FIMR.
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Affiliation(s)
- Henrik Jensen
- Department of Cardiothoracic and Vascular Surgery T and Institute of Clinical Medicine, Aarhus University Hospital-Skejby, Denmark.
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Christensen JH, Soerensen MBT, Linghui Z, Chen S, Jensen MO. Pre-diagnostic digital imaging prediction model to discriminate between malignant melanoma and benign pigmented skin lesion. Skin Res Technol 2010; 16:98-108. [DOI: 10.1111/j.1600-0846.2009.00408.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Jensen H, Jensen MO, Smerup MH, Vind-Kezunovic S, Ringgaard S, Andersen NT, Vestergaard R, Wierup P, Hasenkam JM, Nielsen SL. Impact of papillary muscle relocation as adjunct procedure to mitral ring annuloplasty in functional ischemic mitral regurgitation. Circulation 2009; 120:S92-8. [PMID: 19752392 DOI: 10.1161/circulationaha.108.817833] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND The optimal surgical treatment in functional ischemic mitral regurgitation (FIMR) remains controversial. Recently, a posterior papillary muscle relocation (PMR) technique as adjunct procedure to ring annuloplasty has been proposed to prevent recurrent FIMR. In the present study, we used 3D cardiac MRI to assess the impact of relocating both papillary muscles as adjunct procedure to downsized ring annuloplasty on mitral leaflet coaptation geometry in FIMR pigs. METHODS AND RESULTS Eleven FIMR pigs were randomized to downsized ring annuloplasty (RA; n=6) or RA combined with PMR (RA+PMR, n=5). In the RA+PMR group, a 2-0 Gore-Tex suture was attached to each trigone, exteriorized through the corresponding papillary muscle, mounted on an epicardial pad, and tightened to relocate the myocardium adjacent to the anterior and posterior papillary muscles 5 and 15 mm, respectively. Using 3D MRI, the impact from these interventions on leaflet geometry was assessed. The distance from the posterior papillary muscle to the anterior trigone was reduced significantly more (median values) in the RA+PMR compared with RA animals at end-diastole (-7.9% versus 3.8%, P<0.01) and end-systole (-9.7% versus 2.5%, P=0.02). Accordingly, lateral tethering of the coaptation point (median values) was reduced significantly more in RA+PMR compared with RA animals (-42.8% versus -29.1%, P<0.01). CONCLUSIONS Adding papillary muscle relocation to downsized ring annuloplasty reduced lateral leaflet tethering in a porcine experimental model of FIMR. Therefore, this technique holds promise for reducing persistent and recurrent FIMR in patients.
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Affiliation(s)
- Henrik Jensen
- Department of Cardiothoracic and Vascular Surgery T, Aarhus University Hospital-Skejby, Denmark.
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Jensen MO, Jensen H, Smerup M, Levine RA, Yoganathan AP, Nygaard H, Hasenkam JM, Nielsen SL. Saddle-Shaped Mitral Valve Annuloplasty Rings Experience Lower Forces Compared With Flat Rings. Circulation 2008; 118:S250-5. [DOI: 10.1161/circulationaha.107.746776] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background—
New insight into the 3D dynamic behavior of the mitral valve has prompted a reevaluation of annuloplasty ring designs. Force balance analysis indicates correlation between annulus forces and stresses in leaflets and chords. Improving this stress distribution can intuitively enhance the durability of mitral valve repair. We tested the hypothesis that saddle-shaped annuloplasty rings have superior uniform systolic force distribution compared with a nonuniform force distribution in flat annuloplasty rings.
Methods and Results—
Sixteen 80-kg pigs had a flat (n=8) or saddle-shaped (n=8) mitral annuloplasty ring implanted. Mitral annulus 3D dynamic geometry was obtained with sonomicrometry before ring insertion. Strain gauges mounted on dedicated D-shaped rigid flat and saddle-shaped annuloplasty rings provided the intraoperative force distribution perpendicular to the annular plane. Average systolic annular height to commissural width ratio before ring implantation was 14.0%±1.6%. After flat and saddle shaped ring implantation, the annulus was fixed in the diastolic (9.0%±1.0%) and systolic (14.3%±1.3%) configuration, respectively (
P
<0.01). Force accumulation was seen from the anterior (0.72N±0.14N) and commissural annular segments (average 1.38N±0.27N) of the flat rings. In these segments, the difference between the 2 types of rings was statistically significant (
P
<0.05). The saddle-shaped annuloplasty rings did not experience forces statistically significantly larger than zero in any annular segments.
Conclusions—
Saddle-shaped annuloplasty rings provide superior uniform annular force distribution compared to flat rings and appear to represent a configuration that minimizes out-of-plane forces that could potentially be transmitted to leaflets and chords. This may have important implications for annuloplasty ring selections.
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Affiliation(s)
- Morten O. Jensen
- From the Department of Cardiothoracic and Vascular Surgery (M.O.J., H.J., M.S., H.N., J.M.H., S.L.N.), Institute of Clinical Medicine, Aarhus University Hospital, Skejby, Aarhus, Denmark; Department of Biomedical Engineering (M.O.J., H.N.), Engineering College of Aarhus, Denmark; the Massachusetts General Hospital (R.A.L.), Harvard Medical School, Boston, Mass; and the Wallace H. Coulter School of Biomedical Engineering (A.P.Y.), Georgia Institute of Technology and Emory University, Atlanta, Ga
| | - Henrik Jensen
- From the Department of Cardiothoracic and Vascular Surgery (M.O.J., H.J., M.S., H.N., J.M.H., S.L.N.), Institute of Clinical Medicine, Aarhus University Hospital, Skejby, Aarhus, Denmark; Department of Biomedical Engineering (M.O.J., H.N.), Engineering College of Aarhus, Denmark; the Massachusetts General Hospital (R.A.L.), Harvard Medical School, Boston, Mass; and the Wallace H. Coulter School of Biomedical Engineering (A.P.Y.), Georgia Institute of Technology and Emory University, Atlanta, Ga
| | - Morten Smerup
- From the Department of Cardiothoracic and Vascular Surgery (M.O.J., H.J., M.S., H.N., J.M.H., S.L.N.), Institute of Clinical Medicine, Aarhus University Hospital, Skejby, Aarhus, Denmark; Department of Biomedical Engineering (M.O.J., H.N.), Engineering College of Aarhus, Denmark; the Massachusetts General Hospital (R.A.L.), Harvard Medical School, Boston, Mass; and the Wallace H. Coulter School of Biomedical Engineering (A.P.Y.), Georgia Institute of Technology and Emory University, Atlanta, Ga
| | - Robert A. Levine
- From the Department of Cardiothoracic and Vascular Surgery (M.O.J., H.J., M.S., H.N., J.M.H., S.L.N.), Institute of Clinical Medicine, Aarhus University Hospital, Skejby, Aarhus, Denmark; Department of Biomedical Engineering (M.O.J., H.N.), Engineering College of Aarhus, Denmark; the Massachusetts General Hospital (R.A.L.), Harvard Medical School, Boston, Mass; and the Wallace H. Coulter School of Biomedical Engineering (A.P.Y.), Georgia Institute of Technology and Emory University, Atlanta, Ga
| | - Ajit P. Yoganathan
- From the Department of Cardiothoracic and Vascular Surgery (M.O.J., H.J., M.S., H.N., J.M.H., S.L.N.), Institute of Clinical Medicine, Aarhus University Hospital, Skejby, Aarhus, Denmark; Department of Biomedical Engineering (M.O.J., H.N.), Engineering College of Aarhus, Denmark; the Massachusetts General Hospital (R.A.L.), Harvard Medical School, Boston, Mass; and the Wallace H. Coulter School of Biomedical Engineering (A.P.Y.), Georgia Institute of Technology and Emory University, Atlanta, Ga
| | - Hans Nygaard
- From the Department of Cardiothoracic and Vascular Surgery (M.O.J., H.J., M.S., H.N., J.M.H., S.L.N.), Institute of Clinical Medicine, Aarhus University Hospital, Skejby, Aarhus, Denmark; Department of Biomedical Engineering (M.O.J., H.N.), Engineering College of Aarhus, Denmark; the Massachusetts General Hospital (R.A.L.), Harvard Medical School, Boston, Mass; and the Wallace H. Coulter School of Biomedical Engineering (A.P.Y.), Georgia Institute of Technology and Emory University, Atlanta, Ga
| | - J. Michael Hasenkam
- From the Department of Cardiothoracic and Vascular Surgery (M.O.J., H.J., M.S., H.N., J.M.H., S.L.N.), Institute of Clinical Medicine, Aarhus University Hospital, Skejby, Aarhus, Denmark; Department of Biomedical Engineering (M.O.J., H.N.), Engineering College of Aarhus, Denmark; the Massachusetts General Hospital (R.A.L.), Harvard Medical School, Boston, Mass; and the Wallace H. Coulter School of Biomedical Engineering (A.P.Y.), Georgia Institute of Technology and Emory University, Atlanta, Ga
| | - Sten L. Nielsen
- From the Department of Cardiothoracic and Vascular Surgery (M.O.J., H.J., M.S., H.N., J.M.H., S.L.N.), Institute of Clinical Medicine, Aarhus University Hospital, Skejby, Aarhus, Denmark; Department of Biomedical Engineering (M.O.J., H.N.), Engineering College of Aarhus, Denmark; the Massachusetts General Hospital (R.A.L.), Harvard Medical School, Boston, Mass; and the Wallace H. Coulter School of Biomedical Engineering (A.P.Y.), Georgia Institute of Technology and Emory University, Atlanta, Ga
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Mouritsen OG, Andresen TL, Halperin A, Hansen PL, Jakobsen AF, Jensen UB, Jensen MO, Jørgensen K, Kaasgaard T, Leidy C, Simonsen AC, Peters GH, Weiss M. Activation of interfacial enzymes at membrane surfaces. J Phys Condens Matter 2006; 18:S1293-S1304. [PMID: 21690842 DOI: 10.1088/0953-8984/18/28/s12] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
A host of water-soluble enzymes are active at membrane surfaces and in association with membranes. Some of these enzymes are involved in signalling and in modification and remodelling of the membranes. A special class of enzymes, the phospholipases, and in particular secretory phospholipase A(2) (sPLA(2)), are only activated at the interface between water and membrane surfaces, where they lead to a break-down of the lipid molecules into lysolipids and free fatty acids. The activation is critically dependent on the physical properties of the lipid-membrane substrate. A topical review is given of our current understanding of the physical mechanisms responsible for activation of sPLA(2) as derived from a range of different experimental and theoretical investigations.
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Affiliation(s)
- Ole G Mouritsen
- MEMPHYS-Center for Biomembrane Physics, Physics Department, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
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Abstract
BACKGROUND The E. coli glycerol facilitator, GlpF, selectively conducts glycerol and water, excluding ions and charged solutes. The detailed mechanism of the glycerol conduction and its relationship to the characteristic secondary structure of aquaporins and to the NPA motifs in the center of the channel are unknown. RESULTS Molecular dynamics simulations of GlpF reveal spontaneous glycerol and water conduction driven, on a nanosecond timescale, by thermal fluctuations. The bidirectional conduction, guided and facilitated by the secondary structure, is characterized by breakage and formation of hydrogen bonds for which water and glycerol compete. The conduction involves only very minor changes in the protein structure, and cooperativity between the GlpF monomers is not evident. The two conserved NPA motifs are strictly linked together by several stable hydrogen bonds and their asparagine side chains form hydrogen bonds with the substrates passing the channel in single file. CONCLUSIONS A complete conduction of glycerol through the GlpF was deduced from molecular dynamics simulations, and key residues facilitating the conduction were identified. The nonhelical parts of the two half-membrane-spanning segments expose carbonyl groups towards the channel interior, establishing a curve-linear pathway. The conformational stability of the NPA motifs is important in the conduction and critical for selectivity. Water and glycerol compete in a random manner for hydrogen bonding sites in the protein, and their translocations in single file are correlated. The suggested conduction mechanism should apply to the whole family.
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Affiliation(s)
- M O Jensen
- Beckman Institute, University of Illinois at Urbana-Champaign, 405 N. Mathews, Urbana, IL 61801, USA
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Abstract
To gain insight into the mobility of the occupied ligand-binding pocket of the Rhizomucor miehei lipase we have conducted a rigorous molecular dynamics analysis. The covalently attached inhibitor, ethylhexylphosphonate, was employed as a mimic of the putative tetrahedral intermediate in the esterolytic reaction. Our results show that in this lipase, ligand recognition is influenced by the flexibility of the binding pocket, a feature that is common to many other enzymes. Several regions around the active site were found to move significantly to adapt to the inhibitor. These motions are correlated to the flexibility of the inhibitor. In particular, the hexyl chain of the inhibitor shows considerable mobility, and adjacent residues in the binding cleft accommodate to this flexibility. Pronounced fluctuations in the binding pocket induced by the flexibility of the inhibitor are observed in the hinge region F79-S82, the active site loop region W88-V95 and the protein regions P209-F215/H257-Y260. The flexibility in the regions F79-S82 and H257-Y260, where the shorter ethyl chain is located, indicates that additional space in this binding cleft region is available for accommodating a larger moiety. Fluctuations in the region W88-V95 and P209-F215 are due to the relatively short flexible hexyl carbon chain. This part of the binding pocket could be stiffened by the presence of a longer carbon chain. Though the inhibitor is covalently attached through the phosphonate moiety, interaction of the remainder of the molecule and the enzyme are determined by hydrophobic interactions, where the Van der Waals energies are approximately 25% lower than the electrostatic contributions.
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Affiliation(s)
- G H Peters
- Department of Chemistry, Membrane and Statistical Physics Group, Technical University of Denmark, Lyngby
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Jensen MO, Fontaine AA, Yoganathan AP. Improved in vitro quantification of the force exerted by the papillary muscle on the left ventricular wall: three-dimensional force vector measurement system. Ann Biomed Eng 2001; 29:406-13. [PMID: 11400721 DOI: 10.1114/1.1366672] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Recent developments indicate that the forces acting on the papillary muscles can be a measure of the severity of mitral valve regurgitation. Pathological conditions, such as ischemic heart disease, cause changes in the geometry of the left ventricle and the mitral valve annulus, often resulting in displacement of the papillary muscles relative to the annulus. This can lead to increased tension in the chordae tendineae. This increased tension is transferred to the leaflets, and can disturb the coaptation pattern of the mitral valve. The force balance on the individual components governs the function of the mitral valve. The ability to measure changes in the force distribution from normal to pathological conditions may give insight into the mechanisms of mitral valve insufficiency. A unique in vitro model has been developed that allows quantification of the papillary muscle spatial position and quantification of the three-dimensional force vector applied to the left ventricular wall by the papillary muscles. This system allows for the quantification of the global force exerted on the posterior left ventricular wall from the papillary muscles during simulation of normal and diseased conditions.
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Affiliation(s)
- M O Jensen
- Georgia Institute of Technology/Emory School of Biomedical Engineering, Atlanta 30332-0535, USA
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Jensen MO, Lemmon JD, Gessaghi VC, Conrad CP, Levine RA, Yoganathan AP. Harvested porcine mitral xenograft fixation: impact on fluid dynamic performance. J Heart Valve Dis 2001; 10:111-24. [PMID: 11206757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
BACKGROUND AND AIM OF THE STUDY Recent developments suggest that stentless bioprosthetic mitral valve heterografts should be considered in order to optimize valve hydrodynamics. The fixation process alters the mechanical properties of tissue. This study investigates the changes in mitral valve morphology and hemodynamic performance following fixation. METHODS Porcine mitral valves were excised and attached to a physiological annular ring. Mitral valve function was studied in vitro with a rigid transparent left heart model, allowing transverse and sagittal views. Initial experiments were performed with fresh valves under physiological conditions. Three different papillary muscle positions were used, and each was recorded. After glutaraldehyde fixation, genipin fixation, and cryopreservation, the valves were re-studied while maintaining cardiac output. Performance characteristics before and after fixation were obtained from hydrodynamic pressure and flow data, high-speed video camera, digital video, Doppler ultrasound, and three-dimensional papillary muscle force measurements. Morphology changes were detected by detailed anatomic measurements of the valves before and after fixation. RESULTS Valve length was reduced by 18.5% after fixation with genipin (p <0.001), but not with glutaraldehyde. Cryopreserved valves showed no statistically significant changes in morphology or hydrodynamic performance after preservation. The forward flow opening area was reduced by 12.2% (p <0.001) after glutaraldehyde fixation, and by 32.3% (p = 0.004) after genipin fixation. Thus, maximal forward flow velocity was increased by 33.3% (p = 0.008) after glutaraldehyde fixation and by 52.8% (p = 0.001) after genipin fixation. The flow acceleration was consistent with a funnel shape of the fixed valves causing important flow contraction beyond the orifice (vena contracta). The papillary muscle force increased with apically posterior papillary muscle displacement by 20.4% (p = 0.001) and 101.5% (p <0.001) after glutaraldehyde and genipin fixation, respectively, and total regurgitant volume was increased by 91.6% (p <0.001) and 117.3% (p <0.001), respectively. The work required by the heart simulator to maintain a constant cardiac output at constant vascular resistance increased by 24.2% (p = 0.003) and 34.2% (p = 0.004) after glutaraldehyde and genipin fixation, respectively. CONCLUSION The present study shows that chemical fixation of porcine mitral valves adversely affects the hemodynamics of the valves, increasing overall workload. The effects were more severe after fixation with genipin than with glutaraldehyde. This suggests the need to explore other fixation agents to optimize valvular cardiac function. Cryopreservation had no detrimental effects on valvular hemodynamic performance.
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Affiliation(s)
- M O Jensen
- Georgia Institute of Technology/Emory School of Biomedical Engineering, Atlanta 30332-0535, USA
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Jensen MO, Lindquist KD, Delle Donne EP, Becker WK. Liver metastases: new approaches to a difficult challenge. Abstracts & commentary. Curr Surg 2000; 57:3-7. [PMID: 16093019 DOI: 10.1016/s0149-7944(00)00154-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Affiliation(s)
- M O Jensen
- Department of Surgery, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, North Dakota, USA
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He S, Lemmon JD, Weston MW, Jensen MO, Levine RA, Yoganathan AP. Mitral valve compensation for annular dilatation: in vitro study into the mechanisms of functional mitral regurgitation with an adjustable annulus model. J Heart Valve Dis 1999; 8:294-302. [PMID: 10399664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
BACKGROUND AND AIM OF THE STUDY Mitral annulus dilatation has been identified as an important factor in functional mitral regurgitation (FMR). However, the pathophysiologic interaction of annular dilatation and papillary muscle (PM) displacement in FMR, which occurs clinically in left ventricular (LV) dilatation, is still not well understood. It is difficult to separate these competing factors in vivo, leading to confusion in identifying the real role of the annular dilatation in FMR and its interaction with PM displacement. METHODS To better understand the competing factors, an in vitro model was developed with a D-shaped adjustable mitral annulus that could be changed from 5.5 cm2 to 13.0 cm2 during experiments, independent of varying PM positions. Six excised normal porcine mitral valves were mounted in a left ventricular model with the adjustable annulus device and tested in a physiologic pulsatile flow system under normal cardiac output and left ventricular pressure (5.0 l/min, 120 mmHg). Papillary muscles were placed in normal and then displaced to an apical posterolateral position, to simulate pathological conditions seen clinically. Regurgitation was measured directly by a flow probe and the mitral valve geometry and leaflet coaptation were recorded by video camera through the model's atrium window. In addition, 2D echocardiography was used to evaluate leaflet coaptation and color Doppler flow mapping to detect the regurgitant flow field. RESULTS The results showed that in normal PM position, the mitral regurgitant was consistently at low level until the annulus was enlarged to 1.75 times the normal size, at which time it increased sharply. Papillary muscle apical posterolateral displacement, which simulates a dilated LV, caused regurgitation to occur earlier (1.5 times the normal annulus size), and had an increased regurgitant volume (p < 0.05). The leaflet gaps were first observed at the commissural areas of the valves, consistent with the location of regurgitant jets detected by color Doppler flow mapping. Asymmetric PM displacement created more regurgitation than both the symmetric PM tethering (p = 0.063) and normal PM position (p < 0.01). The regurgitant jets were observed at the same commissural side as the PM displacement, even without significant enlargement of the annulus. CONCLUSIONS This in vitro study provides insight into the interaction between annular dilatation and PM displacement on FMR. The resulting effects and their overall similarity to clinical observation could help further understand the mechanism of FMR and provide additional information to improve future therapeutic strategies.
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Affiliation(s)
- S He
- School of Biomedical Engineering, Georgia Institute of Technology, Atlanta 30332-0535, USA
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Jensen MO, Matthees DJ, Antonenko D. Laser thoracoscopy for pleural effusion. Am Surg 1992; 58:667-9. [PMID: 1485696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
A potential, new, therapeutic modality for the treatment of recurrent symptomatic pleural effusion in a patient with metastatic carcinoma is presented using "minimal access surgery." Diagnosis at the time of thoracoscopy, as well as treatment using free-beam and contact-tip modalities, is outlined in detail. Also, a complication of inter-costal artery bleeding is presented, as well as its solution using the end-firing endoclip applier. This is an effective and useful procedure that should be particularly of interest to surgeons already using various scope methods. Surgeons currently express strong interest in accomplishing diagnosis and treatment goals in a variety of clinical situations using "minimal access surgery," a phrase coined at the 1989 International Congress of the Society of American Gastrointestinal and Endoscopic Surgeons. Enthusiasm about this procedure is evident across the country by the number of laparoscopic courses offered at a variety of institutions. Similarly, the chest allows certain applications of minimal access surgery resulting in accurate diagnosis and possible definitive treatment by use of the thoracoscope.
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Affiliation(s)
- M O Jensen
- Department of Surgery, University of North Dakota, Fargo
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Abstract
Synchronous thyroid and thymic malignancy following childhood thymic irradiation has only been reported in two known cases previously, with a third case identified here. A rationale is presented for following these radiated patients as they age with thyroglobulin and thyroid-stimulating hormone (TSH) levels as a measure of risk of the development of nodular thyroid disease and, if such occurs, for an aggressive surgical approach. There exists a growing population at risk attributable to the success of radiation treatment of Hodgkin's and pediatric head and neck tumors. The question is raised regarding the theoretical benefits of thyroid suppressive therapy in this group at risk. With the instructive case presented, radical surgery for either thymic or thyroid carcinoma and careful monitoring for decades-late local recurrences of thymoma are suggested.
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Affiliation(s)
- M O Jensen
- Department of Surgery, University of North Dakota, Fargo 58108
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