1
|
How Strong Can We Pull? Critical Thresholds for Traction Forces on the Aortic Annulus: Measurements on Fresh Porcine Hearts. Medicina (B Aires) 2022; 58:medicina58081055. [PMID: 36013522 PMCID: PMC9415296 DOI: 10.3390/medicina58081055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 07/28/2022] [Accepted: 08/02/2022] [Indexed: 11/17/2022] Open
Abstract
Background and Objectives: Friable or infected tissue remains a challenge in surgical aortic valve replacement. We recently described the “Caput medusae” method, in which circumferential tourniquets temporarily secure the prosthesis and are then gently knotted. Tourniquets have been shown to develop significantly less force than knots. The current study investigates the critical threshold forces for tissue damage to the aortic annulus. Materials and Methods: In 14 fresh porcine hearts, the aortic valve leaflets were removed and several pledgeted sutures were placed along the annulus at defined locations. The hearts were mounted in a self-constructed device. Incremental traction force was applied to every suture and continuously recorded. The movement of each Teflon pledget was filmed with a high-speed camera. Forces at the moment of pledget “cut-in” as well as complete “tear-out” were determined from the recordings. Results: The average threshold force was determined 9.31 ± 6.04 N for cut-in and 20.41 ± 10.02 N for tear-out. Detailed analysis showed that the right coronary region had lower threshold forces than the other regions (4.77 ± 3.28 N (range, 1.67–12.75 N) vs. 10.67 ± 6.04 N (1.62–26.00 N) for cut-in and 10.67 ± 4.04 N (5.40–18.64 N) vs. 23.33 ± 9.42 N (9.22–51.23 N) for tear-out). The findings are discussed in conjunction with the knot and tourniquet forces from our previous study. Conclusions: Even in healthy tissue, moderate forces can reach a critical level at which a Teflon pledget will cut into the annulus, while a complete tear-out is unlikely. The right coronary portion is more susceptible to damage than the remaining regions. When compared to previous data, forces during manual knotting may exceed the critical cut-in level, while rubber tourniquets may provide a higher safety margin against tissue rupture.
Collapse
|
2
|
Zeng G, Li G, Jia Y, Chen S, Chen P, He Z. Detachment Force of the Helical Anchor in Mitral Annulus. MEDICINE IN NOVEL TECHNOLOGY AND DEVICES 2021. [DOI: 10.1016/j.medntd.2021.100098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
|
3
|
Sulejmani F, Pataky J, Sun W. Mechanical and Structural Evaluation of Tricuspid Bicuspidization in a Porcine Model. Cardiovasc Eng Technol 2020; 11:522-531. [PMID: 32737819 DOI: 10.1007/s13239-020-00480-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 07/22/2020] [Indexed: 01/06/2023]
Abstract
INTRODUCTION Tricuspid regurgitation (TR) affects approximately 1.6 million Americans and is associated with just a 63.9% 1-year survival rate in its moderate to severe forms due to its asymptomatic nature and late diagnosis and surgical referral. As a result, industrial fervor has begun to broach this topic, with several percutaneous treatment devices currently under development. As much remains unknown about the tricuspid apparatus, the mechanics of these procedures remain unquantified. In this study, a testing apparatus and technique for the evaluation of percutaneous tricuspid valve (TV) bicuspidization were developed for the evaluation of these parameters in twelve porcine hearts. METHODS The passive relaxed myocardial state and the active contracted state were each induced in six porcine hearts and the bicuspidization experiment was run twice, the second time after induction of TR. TV annular area, cinching force, static leakage through the TV annulus, and annular ellipticity were quantified and compared among the groups. RESULTS The use of phenol was effective to induce functional TR by increased annular area. Cinching force was not found to differ between any of the testing states, but the bicuspidization experiment was able to reduce the TR annular area to that of its healthy counterpart in addition to reducing static leakage through the TV annulus. Despite appropriately reducing the area, bicuspidization was found to induce a more circular TV annular shape. CONCLUSION Taken together, these results provide a first mechanical analysis of the TV bicuspidization mechanism and may serve as a point of reference for future clinical animal studies.
Collapse
Affiliation(s)
- Fatiesa Sulejmani
- Tissue Mechanics Laboratory, The Wallace H. Coulter, Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, 206 Technology Enterprise Park, 387 Technology Circle, Atlanta, GA, 30313-2412, USA
| | - Joshua Pataky
- Tissue Mechanics Laboratory, The Wallace H. Coulter, Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, 206 Technology Enterprise Park, 387 Technology Circle, Atlanta, GA, 30313-2412, USA
| | - Wei Sun
- Tissue Mechanics Laboratory, The Wallace H. Coulter, Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, 206 Technology Enterprise Park, 387 Technology Circle, Atlanta, GA, 30313-2412, USA.
| |
Collapse
|
4
|
Mathur M, Meador WD, Jazwiec T, Malinowski M, Timek TA, Rausch MK. The Effect of Downsizing on the Normal Tricuspid Annulus. Ann Biomed Eng 2020; 48:655-668. [PMID: 31659604 PMCID: PMC8353055 DOI: 10.1007/s10439-019-02387-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 10/11/2019] [Indexed: 12/17/2022]
Abstract
Tricuspid annuloplasty is a surgical procedure that cinches the valve's annulus in order to reduce regurgitant blood flow. One of its critical parameters is the degree of downsizing. To provide insight into the effect of downsizing, we studied the annulus of healthy sheep during suture annuloplasty. To this end, we implanted fiduciary markers along the annulus of sheep and subsequently performed a DeVega suture annuloplasty. We performed five downsizing steps in each animal while recording hemodynamic and sonomicrometry data in beating hearts. Subsequently, we used splines to approximate the annulus at baseline and at each downsizing step. Based on these approximations we computed clinical metrics of annular shape and dynamics, and the continuous field metrics height, strain, and curvature. With these data, we demonstrated that annular area reduction during downsizing was primarily driven by compression of the anterior annulus. Similarly, reduction in annular dynamics was driven by reduced contractility in the anterior annulus. Finally, changes in global height and eccentricity of the annulus could be explained by focal changes in the continuous height profile and changes in annular curvature. Our findings are important as they provide insight into a regularly performed surgical procedure and may inform the design of transcatheter devices that mimic suture annuloplasty.
Collapse
Affiliation(s)
- Mrudang Mathur
- Department of Mechanical Engineering, University of Texas at Austin, 204 E Dean Keeton Street, Austin, TX, 78712, USA
| | - William D Meador
- Department of Biomedical Engineering, University of Texas at Austin, 107 W Dean Keeton Street, Austin, TX, 78712, USA
| | - Tomasz Jazwiec
- Silesian Centre for Heart Diseases, Department of Cardiac, Vascular and Endovascular Surgery and Transplantology, Medical University of Silesia in Katowice, Zabrze, Poland
| | - Marcin Malinowski
- Department of Cardiac Surgery, School of Medicine in Katowice, Medical University of Silesia, Katowice, Poland
| | - Tomasz A Timek
- Division of Cardiothoracic Surgery, Spectrum Health, Grand Rapids, MI, 49503, USA
| | - Manuel K Rausch
- Departments of Aerospace Engineering & Engineering Mechanics, Biomedical Engineering, University of Texas at Austin, 2617, Wichita Street, Austin, TX, 78712, USA.
| |
Collapse
|
5
|
Mathur M, Jazwiec T, Meador WD, Malinowski M, Goehler M, Ferguson H, Timek TA, Rausch MK. Tricuspid valve leaflet strains in the beating ovine heart. Biomech Model Mechanobiol 2019; 18:1351-1361. [PMID: 30980211 DOI: 10.1007/s10237-019-01148-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 04/03/2019] [Indexed: 12/25/2022]
Abstract
The tricuspid leaflets coapt during systole to facilitate proper valve function and, thus, ensure efficient transport of deoxygenated blood to the lungs. Between their open state and closed state, the leaflets undergo large deformations. Quantification of these deformations is important for our basic scientific understanding of tricuspid valve function and for diagnostic or prognostic purposes. To date, tricuspid valve leaflet strains have never been directly quantified in vivo. To fill this gap in our knowledge, we implanted four sonomicrometry crystals per tricuspid leaflet and six crystals along the tricuspid annulus in a total of five sheep. In the beating ovine hearts, we recorded crystal coordinates alongside hemodynamic data. Once recorded, we used a finite strain kinematic framework to compute the temporal evolutions of area strain, radial strain, and circumferential strain for each leaflet. We found that leaflet strains were larger in the anterior leaflet than the posterior and septal leaflets. Additionally, we found that radial strains were larger than circumferential strains. Area strains were as large as 97% in the anterior leaflet, 31% in the posterior leaflet, and 31% in the septal leaflet. These data suggest that tricuspid valve leaflet strains are significantly larger than those in the mitral valve. Should our findings be confirmed they could suggest either that the mechanobiological equilibrium of tricuspid valve resident cells is different than that of mitral valve resident cells or that the mechanotransductive apparatus between the two varies. Either phenomenon may have important implications for the development of tricuspid valve-specific surgical techniques and medical devices.
Collapse
Affiliation(s)
- M Mathur
- Department of Mechanical Engineering, University of Texas at Austin, Austin, TX, USA
| | - T Jazwiec
- Division of Cardiothoracic Surgery, Spectrum Health, Grand Rapids, MI, USA
- Department of Cardiac, Vascular and Endovascular Surgery and Transplantology, Medical University of Silesia in Katowice, Silesian Centre for Heart Diseases, Zabrze, Poland
| | - W D Meador
- Department of Biomedical Engineering, University of Texas at Austin, 2501 Speedway, Room 7.620, Austin, TX, 78712, USA
| | - M Malinowski
- Division of Cardiothoracic Surgery, Spectrum Health, Grand Rapids, MI, USA
- Department of Cardiac Surgery, School of Medicine in Katowice, Medical University of Silesia, Katowice, Poland
| | - M Goehler
- Division of Cardiothoracic Surgery, Spectrum Health, Grand Rapids, MI, USA
| | - H Ferguson
- Division of Cardiothoracic Surgery, Spectrum Health, Grand Rapids, MI, USA
| | - T A Timek
- Division of Cardiothoracic Surgery, Spectrum Health, Grand Rapids, MI, USA
| | - M K Rausch
- Department of Biomedical Engineering, University of Texas at Austin, 2501 Speedway, Room 7.620, Austin, TX, 78712, USA.
- Department of Aerospace Engineering and Engineering Mechanics, University of Texas at Austin, Austin, TX, USA.
- The Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, TX, USA.
| |
Collapse
|
6
|
Singh-Gryzbon S, Siefert AW, Pierce EL, Yoganathan AP. Tricuspid Valve Annular Mechanics: Interactions with and Implications for Transcatheter Devices. Cardiovasc Eng Technol 2019; 10:193-204. [PMID: 30756336 DOI: 10.1007/s13239-019-00405-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 02/01/2019] [Indexed: 02/06/2023]
Abstract
In the interventional treatment of tricuspid valve regurgitation, the majority of prosthetic devices interact with or are implanted to the tricuspid valve annulus. For new transcatheter technologies, there exists a growing body of clinical experience, literature, and professional discourse related to the difficulties in delivering, securing, and sustaining the function of these devices within the dynamic tricuspid annulus. Many of the difficulties arise from circumstances not encountered in open-heart surgery, namely; a non-arrested heart, indirect visualization, and a reliance on non-suture-based methods. These challenges require the application of procedural techniques or system designs to account for tricuspid annular motion, forces, and underlying tissue strength. Improved knowledge in these interactions will support the goals of improving device systems, their procedures, and patient outcomes. This review aims to describe current concepts of tricuspid annular mechanics, key device and procedural implications, and highlight current knowledge gaps for future consideration.
Collapse
Affiliation(s)
- Shelly Singh-Gryzbon
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology & Emory University, Technology Enterprise Park, 387 Technology Circle NW, Atlanta, GA, 30313-2412, USA
| | - Andrew W Siefert
- Cardiac Implants LLC, 25 Lake Terrace, Tarrytown, NY, 10591, USA
| | - Eric L Pierce
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology & Emory University, Technology Enterprise Park, 387 Technology Circle NW, Atlanta, GA, 30313-2412, USA
| | - Ajit P Yoganathan
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology & Emory University, Technology Enterprise Park, 387 Technology Circle NW, Atlanta, GA, 30313-2412, USA.
| |
Collapse
|
7
|
Use of Computational Fluid Dynamics to Analyze Blood Flow, Hemolysis and Sublethal Damage to Red Blood Cells in a Bileaflet Artificial Heart Valve. FLUIDS 2019. [DOI: 10.3390/fluids4010019] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Artificial heart valves may expose blood to flow conditions that lead to unnaturally high stress and damage to blood cells as well as issues with thrombosis. The purpose of this research was to predict the trauma caused to red blood cells (RBCs), including hemolysis, from the stresses applied to them and their exposure time as determined by analysis of simulation results for blood flow through both a functioning and malfunctioning bileaflet artificial heart valve. The calculations provided the spatial distribution of the Kolmogorov length scales that were used to estimate the spatial and size distributions of the smallest turbulent flow eddies in the flow field. The number and surface area of these eddies in the blood were utilized to predict the amount of hemolysis experienced by RBCs. Results indicated that hemolysis levels are low while suggesting stresses at the leading edge of the leaflet may contribute to subhemolytic damage characterized by shortened circulatory lifetimes and reduced RBC deformability.
Collapse
|