1
|
Garg P, Markl M, Sathananthan J, Sellers SL, Meduri C, Cavalcante J. Restoration of flow in the aorta: a novel therapeutic target in aortic valve intervention. Nat Rev Cardiol 2024; 21:264-273. [PMID: 37880496 DOI: 10.1038/s41569-023-00943-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 09/25/2023] [Indexed: 10/27/2023]
Abstract
Aortic blood flow patterns are closely linked to the morphology and function of the left ventricle, aortic valve and aorta. These flow patterns demonstrate the exceptional adaptability of the cardiovascular system to maintain blood circulation under a broad range of haemodynamic workloads and can be altered in various pathophysiological states. For instance, normal ascending aortic systolic flow is predominantly laminar, whereas abnormal aortic systolic flow is associated with increased eccentricity, vorticity and flow reversal. These flow abnormalities result in reduced aortic conduit function and increased energy loss in the cardiovascular system. Emerging evidence details the association of these flow patterns with loss of aortic compliance, which leads to adverse left ventricular remodelling, poor tissue perfusion, and an increased risk of morbidity and death. In this Perspective article, we review the evidence for the link between aortic flow-related abnormalities and cardiovascular disease and how these changes in aortic flow patterns are emerging as a therapeutic target for aortic valve intervention in first-in-human studies.
Collapse
Affiliation(s)
- Pankaj Garg
- University of East Anglia, Norwich Medical School, Norwich, UK.
- Norfolk and Norwich University Hospitals NHS Foundation Trust, Norwich, UK.
| | - Michael Markl
- Departments of Radiology & Biomedical Engineering, Northwestern University, Feinberg School of Medicine & McCormick School of Engineering, Chicago, IL, USA
| | | | - Stephanie L Sellers
- Cardiovascular Translational Lab, St. Paul's Hospital, University of British Columbia Centre for Heart Lung Innovation, Vancouver, British Columbia, Canada
| | - Chris Meduri
- Department of Cardiology, Karolinska University Hospital, Stockholm, Sweden
| | - João Cavalcante
- Minneapolis Heart Institute, Abbott Northwestern Hospital, Minneapolis, MN, USA
| |
Collapse
|
2
|
Mehmood Z, Assadi H, Grafton-Clarke C, Li R, Matthews G, Alabed S, Girling R, Underwood V, Kasmai B, Zhao X, Ricci F, Zhong L, Aung N, Petersen SE, Swift AJ, Vassiliou VS, Cavalcante J, Geest RJVD, Garg P. Validation of 2D flow MRI for helical and vortical flows. Open Heart 2024; 11:e002451. [PMID: 38458769 PMCID: PMC10928773 DOI: 10.1136/openhrt-2023-002451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2023] [Accepted: 11/09/2023] [Indexed: 03/10/2024] Open
Abstract
PURPOSE The main objective of this study was to develop two-dimensional (2D) phase contrast (PC) methods to quantify the helicity and vorticity of blood flow in the aortic root. METHODS This proof-of-concept study used four-dimensional (4D) flow cardiovascular MR (4D flow CMR) data of five healthy controls, five patients with heart failure with preserved ejection fraction and five patients with aortic stenosis (AS). A PC through-plane generated by 4D flow data was treated as a 2D PC plane and compared with the original 4D flow. Visual assessment of flow vectors was used to assess helicity and vorticity. We quantified flow displacement (FD), systolic flow reversal ratio (sFRR) and rotational angle (RA) using 2D PC. RESULTS For visual vortex flow presence near the inner curvature of the ascending aortic root on 4D flow CMR, sFRR demonstrated an area under the curve (AUC) of 0.955, p<0.001. A threshold of >8% for sFRR had a sensitivity of 82% and specificity of 100% for visual vortex presence. In addition, the average late systolic FD, a marker of flow eccentricity, also demonstrated an AUC of 0.909, p<0.001 for visual vortex flow. Manual systolic rotational flow angle change (ΔsRA) demonstrated excellent association with semiautomated ΔsRA (r=0.99, 95% CI 0.9907 to 0.999, p<0.001). In reproducibility testing, average systolic FD (FDsavg) showed a minimal bias at 1.28% with a high intraclass correlation coefficient (ICC=0.92). Similarly, sFRR had a minimal bias of 1.14% with an ICC of 0.96. ΔsRA demonstrated an acceptable bias of 5.72°-and an ICC of 0.99. CONCLUSION 2D PC flow imaging can possibly quantify blood flow helicity (ΔRA) and vorticity (FRR). These imaging biomarkers of flow helicity and vorticity demonstrate high reproducibility for clinical adoption. TRIALS REGISTRATION NUMBER NCT05114785.
Collapse
Affiliation(s)
- Zia Mehmood
- Norfolk and Norwich University Hospitals NHS Foundation Trust, Norwich, UK
| | - Hosamadin Assadi
- Norfolk and Norwich University Hospitals NHS Foundation Trust, Norwich, UK
- Department of Cardiovascular and Metabolic Health, University of East Anglia Norwich Medical School, Norwich, UK
| | - Ciaran Grafton-Clarke
- Norfolk and Norwich University Hospitals NHS Foundation Trust, Norwich, UK
- Department of Cardiovascular and Metabolic Health, University of East Anglia, Norwich, UK
| | - Rui Li
- Norfolk and Norwich University Hospitals NHS Foundation Trust, Norwich, UK
- Department of Cardiovascular and Metabolic Health, University of East Anglia, Norwich, UK
| | - Gareth Matthews
- Norfolk and Norwich University Hospitals NHS Foundation Trust, Norwich, UK
- Department of Cardiovascular and Metabolic Health, University of East Anglia, Norwich, UK
| | - Samer Alabed
- Department of Infection, Immunity & Cardiovascular Disease, University of Sheffield, Sheffield, UK
| | - Rebekah Girling
- Norfolk and Norwich University Hospitals NHS Foundation Trust, Norwich, UK
| | - Victoria Underwood
- Norfolk and Norwich University Hospitals NHS Foundation Trust, Norwich, UK
| | - Bahman Kasmai
- Norfolk and Norwich University Hospitals NHS Foundation Trust, Norwich, UK
- Department of Cardiovascular and Metabolic Health, University of East Anglia, Norwich, UK
| | | | - Fabrizio Ricci
- Neuroscience, Imaging and Clinical Sciences, Gabriele d'Annunzio University of Chieti and Pescara, Chieti Scalo, Italy
| | | | - Nay Aung
- Queen Mary University of London, London, UK
| | - Steffen Erhard Petersen
- Advanced Cardiovascular Imaging William Harvey Research Institute, The London Chest Hospital, London, UK
| | | | - Vassilios S Vassiliou
- Norfolk and Norwich University Hospitals NHS Foundation Trust, Norwich, UK
- Department of Cardiovascular and Metabolic Health, University of East Anglia, Norwich, UK
| | - João Cavalcante
- Cardiovascular, Cleveland Clinic Foundation, Cleveland, Ohio, USA
| | | | - Pankaj Garg
- Norfolk and Norwich University Hospitals NHS Foundation Trust, Norwich, UK
- Department of Cardiovascular and Metabolic Health, University of East Anglia, Norwich, UK
| |
Collapse
|
3
|
Ebel S, Kühn A, Köhler B, Behrendt B, Riekena B, Preim B, Denecke T, Grothoff M, Gutberlet M. Quantitative 4D flow MRI-derived thoracic aortic normal values of 2D flow MRI parameters in healthy volunteers. ROFO-FORTSCHR RONTG 2024; 196:273-282. [PMID: 37944940 DOI: 10.1055/a-2175-4165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2023]
Abstract
PURPOSE To utilize 4 D flow MRI to acquire normal values of "conventional 2 D flow MRI parameters" in healthy volunteers in order to replace multiple single 2 D flow measurements with a single 4 D flow acquisition. MATERIALS AND METHODS A kt-GRAPPA accelerated 4 D flow sequence was used. Flow volumes were assessed by forward (FFV), backward (BFV), and net flow volumes (NFV) [ml/heartbeat] and flow velocities by axial (VAX) and absolute velocity (VABS) [m/s] in 116 volunteers (58 females, 43 ± 13 years). The aortic regurgitant fraction (RF) was calculated. RESULTS The sex-neutral mean FFV, BFV, NFV, and RF in the ascending aorta were 93.5 ± 14.8, 3.6 ± 2.8, 89.9 ± 0.6 ml/heartbeat, and 3.9 ± 2.9 %, respectively. Significantly higher values were seen in males regarding FFV, BFV, NFV and RF, but there was no sex dependency regarding VAX and VABS. The mean maximum VAX was lower (1.01 ± 0.31 m/s) than VABS (1.23 ± 0.35 m/s). We were able to determine normal ranges for all intended parameters. CONCLUSION This study provides quantitative 4 D flow-derived thoracic aortic normal values of 2 D flow parameters in healthy volunteers. FFV, BFV, NFV, and VAX did not differ significantly from single 2 D flow acquisitions and could therefore replace time-consuming multiple single 2 D flow acquisitions. VABS should not be used interchangeably. KEY POINTS · 4 D flow MRI can be used to replace 2 D flow MRI measurements.. · The parameter absolute velocities can be assessed by 4 D flow MRI.. · There are sex-dependent differences regarding forward, backward, net aortic blood flow and the aortic valve regurgitant fraction..
Collapse
Affiliation(s)
- Sebastian Ebel
- Diagnostic and Interventional Radiology, Leipzig University, Leipzig, Germany
| | - Alexander Kühn
- Diagnostic and Interventional Radiology, Leipzig Heart Centre University Hospital, Leipzig, Germany
| | - Benjamin Köhler
- Simulation and Graphics, Otto von Guericke Universität Magdeburg, Germany
| | - Benjamin Behrendt
- Simulation and Graphics, Otto von Guericke Universität Magdeburg, Germany
| | - Boris Riekena
- Diagnostic and Interventional Radiology, Leipzig Heart Centre University Hospital, Leipzig, Germany
| | - Bernhard Preim
- Simulation and Graphics, Otto von Guericke Universität Magdeburg, Germany
| | - Timm Denecke
- Diagnostic and Interventional Radiology, Leipzig University, Leipzig, Germany
| | - Matthias Grothoff
- Diagnostic and Interventional Radiology, Leipzig Heart Centre University Hospital, Leipzig, Germany
| | - Matthias Gutberlet
- Diagnostic and Interventional Radiology, Leipzig Heart Centre University Hospital, Leipzig, Germany
| |
Collapse
|
4
|
Ebel S, Köhler B, Aggarwal A, Preim B, Behrendt B, Jung B, Gohmann RF, Riekena B, Borger M, Lurz P, Denecke T, Grothoff M, Gutberlet M. Comparison of aortic blood flow rotational direction in healthy volunteers and patients with bicuspid aortic valves using volumetric velocity-sensitive cardiovascular magnetic resonance imaging. Quant Imaging Med Surg 2023; 13:7973-7986. [PMID: 38106267 PMCID: PMC10722022 DOI: 10.21037/qims-23-183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 09/13/2023] [Indexed: 12/19/2023]
Abstract
Background The rotational direction (RD) of helical blood flow can be classified as either a clockwise (RD+) or counter-clockwise (RD-) flow. We hypothesized that this simple classification might not be sufficient for analysis in vivo and a simultaneous existence of RD+/- may occur. We utilized volumetric velocity-sensitive cardiovascular magnetic resonance imaging (4D flow MRI) to analyze rotational blood flow in the thoracic aorta. Methods Forty volunteers (22 females; mean age, 41±16 years) and seventeen patients with bicuspid aortic valves (BAVs) (9 females; mean age, 42±14 years) were prospectively included. The RDs and the calculation of the rotating blood volumes (RBVs) in the thoracic aorta were performed using a pathline-projection strategy. Results We could confirm a mainly clockwise RD in the ascending, descending aorta and in the aortic arch. Furthermore, we found a simultaneous existence of RD+/RD-. The RD+/--volume in the ascending aorta was significantly higher in BAV patients, the mean RD+/RD- percentage was approximately 80%/20% vs. 60%/40% in volunteers (P<0.01). The maximum RBV always occurred during systole. There was significantly more clockwise than counter-clockwise rotational flow in the ascending aorta (P<0.01) and the aortic arch (P<0.01), but no significant differences in the descending aorta (P=0.48). Conclusions A simultaneous occurrence of RD+/RD- indicates that a simple categorization in either of both is insufficient to describe blood flow in vivo. Rotational flow in the ascending aorta and in the aortic arch differs significantly from flow in the descending aorta. BAV patients show significantly more clockwise rotating volume in the ascending aorta compared to healthy volunteers.
Collapse
Affiliation(s)
- Sebastian Ebel
- Department of Diagnostic and Interventional Radiology, University of Leipzig – Heart Centre, Leipzig, Germany
- Department of Diagnostic and Interventional Radiology, University of Leipzig, Leipzig, Germany
| | - Benjamin Köhler
- Department of Simulation and Graphics, University of Magdeburg, Magdeburg, Germany
| | | | - Bernhard Preim
- Department of Simulation and Graphics, University of Magdeburg, Magdeburg, Germany
| | - Benjamin Behrendt
- Department of Simulation and Graphics, University of Magdeburg, Magdeburg, Germany
| | - Bernd Jung
- Department of Diagnostic, Interventional and Paediatric Radiology, University of Bern, Bern, Switzerland
| | - Robin F. Gohmann
- Department of Diagnostic and Interventional Radiology, University of Leipzig – Heart Centre, Leipzig, Germany
| | - Boris Riekena
- Department of Diagnostic and Interventional Radiology, University of Leipzig – Heart Centre, Leipzig, Germany
| | - Michael Borger
- Department of Cardiac Surgery, University Leipzig – Heart Centre, Leipzig, Germany
| | - Philipp Lurz
- Department of Cardiology, University Leipzig – Heart Centre, Leipzig, Germany
| | - Timm Denecke
- Department of Diagnostic and Interventional Radiology, University of Leipzig, Leipzig, Germany
| | - Matthias Grothoff
- Department of Diagnostic and Interventional Radiology, University of Leipzig – Heart Centre, Leipzig, Germany
| | - Matthias Gutberlet
- Department of Diagnostic and Interventional Radiology, University of Leipzig – Heart Centre, Leipzig, Germany
| |
Collapse
|
5
|
Meuschke M, Niemann U, Behrendt B, Gutberlet M, Preim B, Lawonn K. GUCCI - Guided Cardiac Cohort Investigation of Blood Flow Data. IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS 2023; 29:1876-1892. [PMID: 34882556 DOI: 10.1109/tvcg.2021.3134083] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
We present the framework GUCCI (Guided Cardiac Cohort Investigation), which provides a guided visual analytics workflow to analyze cohort-based measured blood flow data in the aorta. In the past, many specialized techniques have been developed for the visual exploration of such data sets for a better understanding of the influence of morphological and hemodynamic conditions on cardiovascular diseases. However, there is a lack of dedicated techniques that allow visual comparison of multiple data sets and defined cohorts, which is essential to characterize pathologies. GUCCI offers visual analytics techniques and novel visualization methods to guide the user through the comparison of predefined cohorts, such as healthy volunteers and patients with a pathologically altered aorta. The combination of overview and glyph-based depictions together with statistical cohort-specific information allows investigating differences and similarities of the time-dependent data. Our framework was evaluated in a qualitative user study with three radiologists specialized in cardiac imaging and two experts in medical blood flow visualization. They were able to discover cohort-specific characteristics, which supports the derivation of standard values as well as the assessment of pathology-related severity and the need for treatment.
Collapse
|
6
|
Ebel S, Kühn A, Aggarwal A, Köhler B, Behrendt B, Gohmann R, Riekena B, Lücke C, Ziegert J, Vogtmann C, Preim B, Kropf S, Jung B, Denecke T, Grothoff M, Gutberlet M. Quantitative normal values of helical flow, flow jets and wall shear stress of healthy volunteers in the ascending aorta. Eur Radiol 2022; 32:8597-8607. [PMID: 35612663 DOI: 10.1007/s00330-022-08866-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 04/08/2022] [Accepted: 05/08/2022] [Indexed: 11/26/2022]
Abstract
OBJECTIVES 4D flow MRI enables quantitative assessment of helical flow. We sought to generate normal values and elucidate changes of helical flow (duration, volume, length, velocities and rotational direction) and flow jet (displacement, flow angle) as well as wall shear stress (WSS). METHODS We assessed the temporal helical existence (THEX), maximum helical volume (HVmax), accumulated helical volume (HVacc), accumulated helical volume length (HVLacc), maximum forward velocity (maxVfor), maximum circumferential velocity (maxVcirc), rotational direction (RD) and maximum wall shear stress (WSS) as reported elsewhere using the software tool Bloodline in 86 healthy volunteers (46 females, mean age 41 ± 13 years). RESULTS WSS decreased by 42.1% and maxVfor by 55.7% across age. There was no link between age and gender regarding the other parameters. CONCLUSION This study provides age-dependent normal values regarding WSS and maxVfor and age- and gender-independent normal values regarding THEX, HVmax, HVacc, HVLacc, RD and maxVcirc. KEY POINTS • 4D flow provides numerous new parameters; therefore, normal values are mandatory. • Wall shear stress decreases over age. • Maximum helical forward velocity decreases over age.
Collapse
Affiliation(s)
- Sebastian Ebel
- Department of Diagnostic and Interventional Radiology, University of Leipzig - Heart Centre, Leipzig, Germany.
- Department of Diagnostic and Interventional Radiology, University of Leipzig, Liebigstr. 20, 04103, Leipzig, Germany.
| | - Alexander Kühn
- Department of Diagnostic and Interventional Radiology, University of Leipzig - Heart Centre, Leipzig, Germany
| | - Abhinav Aggarwal
- Department of Diagnostic and Interventional Radiology, University of Leipzig - Heart Centre, Leipzig, Germany
- Department of Radiology, Mata Chanan Devi Hospital of New Delhi, New Delhi, India
| | - Benjamin Köhler
- Department of Simulation and Graphics, University of Magdeburg, Magdeburg, Germany
| | - Benjamin Behrendt
- Department of Simulation and Graphics, University of Magdeburg, Magdeburg, Germany
| | - Robin Gohmann
- Department of Diagnostic and Interventional Radiology, University of Leipzig - Heart Centre, Leipzig, Germany
| | - Boris Riekena
- Department of Diagnostic and Interventional Radiology, University of Leipzig - Heart Centre, Leipzig, Germany
| | - Christian Lücke
- Department of Diagnostic and Interventional Radiology, University of Leipzig - Heart Centre, Leipzig, Germany
| | - Juliane Ziegert
- Department of Diagnostic and Interventional Radiology, University of Leipzig - Heart Centre, Leipzig, Germany
| | - Charlotte Vogtmann
- Department of Diagnostic and Interventional Radiology, University of Leipzig - Heart Centre, Leipzig, Germany
| | - Bernhard Preim
- Department of Simulation and Graphics, University of Magdeburg, Magdeburg, Germany
| | - Siegfried Kropf
- Department for Biometry and Medical Informatics, University of Magdeburg, Magdeburg, Germany
| | - Bernd Jung
- Department of Diagnostic, Interventional and Paediatric Radiology, University of Bern, Bern, Switzerland
| | - Timm Denecke
- Department of Diagnostic and Interventional Radiology, University of Leipzig, Liebigstr. 20, 04103, Leipzig, Germany
| | - Matthias Grothoff
- Department of Diagnostic and Interventional Radiology, University of Leipzig - Heart Centre, Leipzig, Germany
| | - Matthias Gutberlet
- Department of Diagnostic and Interventional Radiology, University of Leipzig - Heart Centre, Leipzig, Germany
| |
Collapse
|
7
|
Holtackers RJ, Wildberger JE, Wintersperger BJ, Chiribiri A. Impact of Field Strength in Clinical Cardiac Magnetic Resonance Imaging. Invest Radiol 2021; 56:764-772. [PMID: 34261084 DOI: 10.1097/rli.0000000000000809] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
ABSTRACT Cardiac magnetic resonance imaging (MRI) is widely applied for the noninvasive assessment of cardiac structure and function, and for tissue characterization. For more than 2 decades, 1.5 T has been considered the field strength of choice for cardiac MRI. Although the number of 3-T systems significantly increased in the past 10 years and numerous new developments were made, challenges seem to remain that hamper a widespread clinical use of 3-T MR systems for cardiac applications. As the number of clinical cardiac applications is increasing, with each having their own benefits at both field strengths, no "holy grail" field strength exists for cardiac MRI that one should ideally use. This review describes the physical differences between 1.5 and 3 T, as well as the effect of these differences on major (routine) cardiac MRI applications, including functional imaging, edema imaging, late gadolinium enhancement, first-pass stress perfusion, myocardial mapping, and phase contrast flow imaging. For each application, the advantages and limitations at both 1.5 and 3 T are discussed. Solutions and alternatives are provided to overcome potential limitations. Finally, we briefly elaborate on the potential use of alternative field strengths (ie, below 1.5 T and above 3 T) for cardiac MRI and conclude with field strength recommendations for the future of cardiac MRI.
Collapse
|
8
|
Bruecker C, Li Q. Possible Early Generation of Physiological Helical Flow Could Benefit the Triflo Trileaflet Heart Valve Prosthesis Compared to Bileaflet Valves. Bioengineering (Basel) 2020; 7:bioengineering7040158. [PMID: 33302564 PMCID: PMC7763138 DOI: 10.3390/bioengineering7040158] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 11/17/2020] [Accepted: 12/07/2020] [Indexed: 11/16/2022] Open
Abstract
Background—Physiological helical flow in the ascending aorta has been well documented in the last two decades, accompanied by discussions on possible physiological benefits of such axial swirl. Recent 4D-MRI studies on healthy volunteers have found indications of early generation of helical flow, early in the systole and close to the valve plane. Objectives—Firstly, the aim of the study is to investigate the hypothesis of premature swirl existence in the ventricular outflow tract leading to helical flow in the valve plane, and second to investigate the possible impact of two different mechanical valve designs on the preservation of this early helical flow and its subsequent hemodynamic consequences. Methods—We use a pulse duplicator with an aortic arch and High-Speed Particle Image Velocimetry to document the flow evolution in the systolic cycle. The pulse-duplicator is modified with a swirl-generating insert to generate early helical flow in the valve plane. Special focus is paid to the interaction of such helical flow with different designs of mechanical prosthetic heart valves, comparing a classical bileaflet mechanical heart valve, the St. Jude Medical Regent valve (SJM Regent BMHV), with the Triflo trileaflet mechanical heart valve T2B version (Triflo TMHV). Results—When the swirl-generator is inserted, a vortex is generated in the core flow, demonstrating early helical flow in the valve plane, similar to the observations reported in the recent 4D-MRI study taken for comparison. For the Triflo trileaflet valve, the early helical flow is not obstructed in the central orifice, similar as in the case of the natural valve. Conservation of angular momentum leads to radial expansion of the core flow and flattening of the axial flow profile downstream in the arch. Furthermore, the early helical flow helps to overcome separation at the outer and inner curvature. In contrast, the two parallel leaflets for the bileaflet valve impose a flow straightener effect, annihilating the angular momentum, which has a negative impact on kinetic energy of the flow. Conclusion—The results imply better hemodynamics for the Triflo trileaflet valve based on hydrodynamic arguments under the discussed hypothesis. In addition, it makes the Triflo valve a better candidate for valve replacements in patients with a pathological generation of nonaxial velocity in the ventricle outflow tract.
Collapse
|
9
|
Kharabish A, Belker K, Martinoff S, Ewert P, Hennemuth A, Huellebrand M, Stern H, Meierhofer C. Intraindividual validation of 4D flow measurement against 2D flow measurements in complex flow patterns in routine clinical cardiovascular magnetic resonance of bicuspid aortic valve. THE EGYPTIAN JOURNAL OF RADIOLOGY AND NUCLEAR MEDICINE 2020. [DOI: 10.1186/s43055-020-00331-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Abstract
Background
Comparing four-dimensional flow against two-dimensional flow measurements in patients with complex flow pattern is still lacking. This study aimed to compare four-dimensional against the two-dimensional flow measurement in patients with bicuspid aortic valve and to test potentials of four-dimensional operator-dependent sources of error.
Results
The two- and four-dimensional flow data sets of sixteen patients with bicuspid aortic valve and eighteen healthy subjects were studied. Flow analyses were performed by two observers blindly. Patients with bicuspid aortic valve mean differences between the two- and four-dimensional measurements in both observers were − 8 and − 4 ml, respectively. Four-dimensional measurements resulted in systematically higher flow values than the two-dimensional flow in bicuspid aortic valve patients. The upper and lower limits of agreement between the two- and four-dimensional measurements by both observers were + 12/− 28 ml and + 14/− 21 ml, respectively. In the healthy volunteers, mean differences between the two- and four-dimensional measurements in both observers were ± 0 and + 1 ml, respectively. The upper and lower limits of agreement between the two- and four-dimensional measurements by both observers were + 21/− 18 ml and + 12/− 13 ml, respectively. Inter-observer variability in four-dimensional flow measurement was 4% mean net forward flow in bicuspid aortic valve patients and 8% in healthy volunteers.
Conclusion
Inter-observer variability in four-dimensional flow assessment is 8% or less which is acceptable for clinical cardiac MRI routine. There is close agreement of two- and four-dimensional flow tools in normal and complex flow pattern. In complex flow pattern, however, four-dimensional flow measurement picks up 4–9% higher flow values. It seems, therefore, that four-dimensional flow is closer to real flow values than two-dimensional flow, which is however to be proven by further studies.
Collapse
|