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Sahni A, Marshall L, Cetatoiu MA, Davee J, Schulz N, Eickhoff ER, St Clair N, Ghelani S, Prakash A, Hammer PE, Hoganson DM, Del Nido PJ, Rathod RH, Govindarajan V. Biomechanical Analysis of Age-Dependent Changes in Fontan Power Loss. Ann Biomed Eng 2024; 52:2440-2456. [PMID: 38753109 DOI: 10.1007/s10439-024-03534-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Accepted: 05/02/2024] [Indexed: 08/17/2024]
Abstract
The hemodynamics in Fontan patients with single ventricles rely on favorable flow and energetics, especially in the absence of a subpulmonary ventricle. Age-related changes in energetics for extracardiac and lateral tunnel Fontan procedures are not well understood. Vorticity (VOR) and viscous dissipation rate (VDR) are two descriptors that can provide insights into flow dynamics and dissipative areas in Fontan pathways, potentially contributing to power loss. This study examined power loss and its correlation with spatio-temporal flow descriptors (vorticity and VDR). Data from 414 Fontan patients were used to establish a relationship between the superior vena cava (SVC) to inferior vena cava (IVC) flow ratio and age. Computational flow modeling was conducted for both extracardiac conduits (ECC, n = 16) and lateral tunnels (LT, n = 25) at different caval inflow ratios of 2, 1, and 0.5 that corresponded with ages 3, 8, and 15+. In both cohorts, vorticity and VDR correlated well with PL, but ECC cohort exhibited a slightly stronger correlation for PL-VOR (>0.83) and PL-VDR (>0.89) than that for LT cohort (>0.76 and > 0.77, respectively) at all ages. Our data also suggested that absolute and indexed PL increase (p < 0.02) non-linearly as caval inflow changes with age and are highly patient-specific. Comparison of indexed power loss between our ECC and LT cohort showed that while ECC had a slightly higher median PL for all 3 caval inflow ratio examined (3.3, 8.3, 15.3) as opposed to (2.7, 7.6, 14.8), these differences were statistically non-significant. Lastly, there was a consistent rise in pressure gradient across the TCPC with age-related increase in IVC flows for both ECC and LT Fontan patient cohort. Our study provided hemodynamic insights into Fontan energetics and how they are impacted by age-dependent change in caval inflow. This workflow may help assess the long-term sustainability of the Fontan circulation and inform the design of more efficient Fontan conduits.
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Affiliation(s)
- A Sahni
- Department of Cardiac Surgery, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA, 02115, USA
| | - L Marshall
- Department of Cardiac Surgery, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA, 02115, USA
| | - M A Cetatoiu
- Department of Cardiac Surgery, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA, 02115, USA
| | - J Davee
- Department of Cardiac Surgery, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA, 02115, USA
| | - N Schulz
- Department of Cardiac Surgery, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA, 02115, USA
| | - E R Eickhoff
- Department of Cardiac Surgery, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA, 02115, USA
| | - N St Clair
- Department of Cardiac Surgery, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA, 02115, USA
| | - S Ghelani
- Department of Cardiology, Boston Children's Hospital, Boston, MA, USA
- Department of Pediatrics, Harvard Medical School, Boston, MA, USA
| | - A Prakash
- Department of Cardiology, Boston Children's Hospital, Boston, MA, USA
- Department of Pediatrics, Harvard Medical School, Boston, MA, USA
| | - P E Hammer
- Department of Cardiac Surgery, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA, 02115, USA
- Department of Surgery, Harvard Medical School, Boston, MA, USA
| | - D M Hoganson
- Department of Cardiac Surgery, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA, 02115, USA
- Department of Surgery, Harvard Medical School, Boston, MA, USA
| | - P J Del Nido
- Department of Cardiac Surgery, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA, 02115, USA
- Department of Surgery, Harvard Medical School, Boston, MA, USA
| | - R H Rathod
- Department of Cardiology, Boston Children's Hospital, Boston, MA, USA
- Department of Pediatrics, Harvard Medical School, Boston, MA, USA
| | - Vijay Govindarajan
- Department of Cardiac Surgery, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA, 02115, USA.
- Department of Surgery, Harvard Medical School, Boston, MA, USA.
- Department of Internal Medicine (Cardiology), The University of Texas Health Science Center at Houston, Houston, TX, USA.
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2
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Govindarajan V, Kolanjiyil A, Wanna C, Kim H, Prakash S, Chandran KB, McPherson DD, Johnson NP. Biomechanical Evaluation of Aortic Valve Stenosis by Means of a Virtual Stress Test: A Fluid-Structure Interaction Study. Ann Biomed Eng 2024; 52:414-424. [PMID: 37957528 DOI: 10.1007/s10439-023-03389-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2023] [Accepted: 10/15/2023] [Indexed: 11/15/2023]
Abstract
The impact of aortic valve stenosis (AS) extends beyond the vicinity of the narrowed leaflets into the left ventricle (LV) and into the systemic vasculature because of highly unpredictable valve behavior and complex blood flow in the ascending aorta that can be attributed to the strong interaction between the narrowed cusps and the ejected blood. These effects can become exacerbated during exercise and may have implications for disease progression, accurate diagnosis, and timing of intervention. In this 3-D patient-specific study, we employ strongly coupled fluid-structure interaction (FSI) modeling to perform a comprehensive biomechanical evaluation of systolic ejection dynamics in a stenosed aortic valve (AV) during increasing LV contraction. Our model predictions reveal that the heterogeneous ∆P vs. Q relationship that was observed in our previous clinical study can be attributed to a non-linear increase (by ~ 1.5-fold) in aortic valve area as LV heart rate increases from 70 to 115 bpm. Furthermore, our results show that even for a moderately stenotic valve, increased LV contraction during exercise can lead to high-velocity flow turbulence (Re = 11,700) in the aorta similar to that encountered with a severely stenotic valve (Re ~ 10,000), with concomitant greater viscous loss (~3-fold increase) and elevated wall stress in the ascending aorta. Our FSI predictions also reveal that individual valve cusps undergo distinct and highly non-linear increases (>100%) in stress during exercise, potentially contributing to progressive calcification. Such quantitative biomechanical evaluations from realistic FSI workflows provide insights into disease progression and can be integrated with current stress testing for AS patients to comprehensively predict hemodynamics and valve function under both baseline and exercise conditions.
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Affiliation(s)
- Vijay Govindarajan
- Division of Cardiology, Department of Internal Medicine, McGovern Medical School, The University of Texas Health Science at Houston, 1881 East Road, Houston, TX, 77054, USA.
- Boston Children's Hospital, Boston, MA, USA.
- Harvard Medical School, Boston, MA, USA.
| | | | - Charles Wanna
- Division of Cardiology, Department of Internal Medicine, McGovern Medical School, The University of Texas Health Science at Houston, 1881 East Road, Houston, TX, 77054, USA
| | - Hyunggun Kim
- Division of Cardiology, Department of Internal Medicine, McGovern Medical School, The University of Texas Health Science at Houston, 1881 East Road, Houston, TX, 77054, USA
- Sungkyunkwan University, Suwon, Gyeonggi, Korea
| | - Siddharth Prakash
- Division of Cardiology, Department of Internal Medicine, McGovern Medical School, The University of Texas Health Science at Houston, 1881 East Road, Houston, TX, 77054, USA
| | - Krishnan B Chandran
- Division of Cardiology, Department of Internal Medicine, McGovern Medical School, The University of Texas Health Science at Houston, 1881 East Road, Houston, TX, 77054, USA
- The University of Iowa, Iowa City, IA, USA
| | - David D McPherson
- Division of Cardiology, Department of Internal Medicine, McGovern Medical School, The University of Texas Health Science at Houston, 1881 East Road, Houston, TX, 77054, USA
| | - Nils P Johnson
- Division of Cardiology, Department of Internal Medicine, McGovern Medical School, The University of Texas Health Science at Houston, 1881 East Road, Houston, TX, 77054, USA
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Khalili O, Asgari M. Fluid-structure interaction and structural simulation of high acceleration effects on surgical repaired human mitral valve biomechanics. Proc Inst Mech Eng H 2023; 237:1248-1260. [PMID: 37846647 DOI: 10.1177/09544119231200367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2023]
Abstract
Mitral valve dynamics depend on force stability in the mitral leaflets, the mitral annulus, the chordae tendineae, and the papillary muscles. In chordal rupture conditions, the proper function of the valve disrupts, causing mitral regurgitation, the most prevalent valvular disease. In this study, Structural and FSI frameworks were employed to study valve dynamics in healthy, pathologic, and repaired states. Anisotropic, non-linear, hyper-elastic material properties applied to tissues of the valve while the first-order Ogden model reflected the best compatibility with the empirical data. Hemodynamic blood pressure of the cardiovascular system is applied on the leaflets as uniform loads varying by time, and exposure to high acceleration loads imposed on models. Immersed boundary method used for simulation of fluid in a cardiac cycle. In comparison between healthy and pathologic models, stress values and chordal tensions are increased, by nearly threefold and twofold, respectively. Stress concentration on leaflets is reduced by 75% after performing a successful surgical repair on the pathological model. Crash acceleration loads led to more significant stress and chordae tension on models, by 27% and 23%, respectively. It is concluded that a more sophisticated model could lead to a better understanding of human heart valve biomechanics in various conditions. If a preoperative plan is developed based on these modeling methods, the requirement for multiple successive repairs would be eliminated, operative times are shortened, and patient outcomes are improved.
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Affiliation(s)
- Omid Khalili
- Faculty of Mechanical Engineering, K. N. Toosi University of Technology, Tehran, Iran
| | - Masoud Asgari
- Faculty of Mechanical Engineering, K. N. Toosi University of Technology, Tehran, Iran
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Chan JSK, Lau DHH, Fan Y, Lee APW. Fragmented Vortex in Heart Failure With Reduced Ejection Fraction: A Prospective Vector Flow Mapping Study. ULTRASOUND IN MEDICINE & BIOLOGY 2023; 49:982-988. [PMID: 36581516 DOI: 10.1016/j.ultrasmedbio.2022.12.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 11/29/2022] [Accepted: 12/03/2022] [Indexed: 06/17/2023]
Abstract
OBJECTIVE Heart failure with reduced ejection fraction (HFrEF) is associated with structural and functional left ventricular changes. We compared intracardiac vortices between patients with HFrEF and normal participants using echocardiographic vector flow mapping, a novel intracardiac vortex analysis technology. METHODS Transthoracic echocardiography was performed on 20 patients with HFrEF (age: 61 ± 15 y, 15 men) and 20 normal participants (age: 59 ± 12 y, 12 men) age- and sex-balanced at the cohort level. Systolic and diastolic energy loss, area (indexed by left ventricular end-diastolic diameter), circulation (reflects vortex strength) and relative positions of the largest vortex during systole (S-vortex), early (E-vortex) and late (A-vortex) diastole and maximal number of vortices in a single frame (MNV) were assessed. DISCUSSION Patients with HFrEF had disproportionately sized vortices with smaller indexed vortex areas (p < 0.0001), and more fragmented vortices with higher MNV during both systole (p = 0.030) and diastole (p < 0.0001). These accompanied higher diastolic energy loss (p = 0.001). Additionally, the E-vortex (p = 0.002) and A-vortex (p < 0.0001) were more apically positioned, and the S-vortex was weaker (p = 0.033) in patients with HFrEF. More severe fragmentation (higher MNV) correlated with worse energy efficiency (higher energy loss). CONCLUSION Patients with HFrEF had more fragmented intracardiac vortices and lower energy efficiency predominantly during diastole.
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Affiliation(s)
- Jeffrey Shi Kai Chan
- Division of Cardiology, Department of Medicine and Therapeutics, Prince of Wales Hospital, Chinese University of Hong Kong, Hong Kong, China; Laboratory of Cardiac Imaging and 3D Printing, Li Ka Shing Institute of Health Sciences, Hong Kong, China
| | - Dawnie Ho Hei Lau
- Division of Cardiology, Department of Medicine and Therapeutics, Prince of Wales Hospital, Chinese University of Hong Kong, Hong Kong, China; Laboratory of Cardiac Imaging and 3D Printing, Li Ka Shing Institute of Health Sciences, Hong Kong, China
| | - Yiting Fan
- Department of Cardiology, Shanghai Chest Hospital, Shanghai Jiao Tong University, Xu Hui District, Shanghai, China
| | - Alex Pui-Wai Lee
- Division of Cardiology, Department of Medicine and Therapeutics, Prince of Wales Hospital, Chinese University of Hong Kong, Hong Kong, China; Laboratory of Cardiac Imaging and 3D Printing, Li Ka Shing Institute of Health Sciences, Hong Kong, China.
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Canè F, Delcour L, Luigi Redaelli AC, Segers P, Degroote J. A CFD study on the interplay of torsion and vortex guidance by the mitral valve on the left ventricular wash-out making use of overset meshes (Chimera technique). FRONTIERS IN MEDICAL TECHNOLOGY 2022; 4:1018058. [PMID: 36619345 PMCID: PMC9814007 DOI: 10.3389/fmedt.2022.1018058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 11/15/2022] [Indexed: 12/24/2022] Open
Abstract
Cardiovascular disease often occurs with silent and gradual alterations of cardiac blood flow that can lead to the onset of chronic pathological conditions. Image-based patient-specific Computational Fluid Dynamics (CFD) models allow for an extensive quantification of the flow field beyond the direct capabilities of medical imaging techniques that could support the clinicians in the early diagnosis, follow-up, and treatment planning of patients. Nonetheless, the large and impulsive kinematics of the left ventricle (LV) and the mitral valve (MV) pose relevant modeling challenges. Arbitrary Lagrangian-Eulerian (ALE) based computational fluid dynamics (CFD) methods struggle with the complex 3D mesh handling of rapidly moving valve leaflets within the left ventricle (LV). We, therefore, developed a Chimera-based (overset meshing) method to build a patient-specific 3D CFD model of the beating LV which includes a patient-inspired kinematic model of the mitral valve (LVMV). Simulations were performed with and without torsion. In addition, to evaluate how the intracardiac LV flow is impacted by the MV leaflet kinematics, a third version of the model without the MV was generated (LV with torsion). For all model versions, six cardiac cycles were simulated. All simulations demonstrated cycle-to-cycle variations that persisted after six cycles but were albeit marginal in terms of the magnitude of standard deviation of velocity and vorticity which may be related to the dissipative nature of the numerical scheme used. The MV was found to have a crucial role in the development of the intraventricular flow by enhancing the direct flow, the apical washout, and the propagation of the inlet jet towards the apical region. Consequently, the MV is an essential feature in the patient-specific CFD modeling of the LV. The impact of torsion was marginal on velocity, vorticity, wall shear stress, and energy loss, whereas it resulted to be significant in the evaluation of particle residence times. Therefore, including torsion could be considered in patient-specific CFD models of the LV, particularly when aiming to study stasis and residence time. We conclude that, despite some technical limitations encountered, the Chimera technique is a promising alternative for ALE methods for 3D CFD models of the heart that include the motion of valve leaflets.
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Affiliation(s)
- Federico Canè
- IBiTech – bioMMeda, Department of Electronics and Information Systems, Ghent University, Ghent, Belgium,Correspondence: Federico Canè
| | - Lucas Delcour
- Department of Electromechanical, Systems and Metal Engineering, Ghent University, Ghent, Belgium
| | | | - Patrick Segers
- IBiTech – bioMMeda, Department of Electronics and Information Systems, Ghent University, Ghent, Belgium
| | - Joris Degroote
- Department of Electromechanical, Systems and Metal Engineering, Ghent University, Ghent, Belgium
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6
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Brunel L, Williams ZA, Yastrebov K, Robinson BM, Wise IK, Paterson HS, Bannon PG. Splitting the anterior mitral leaflet impairs left ventricular function in an ovine model. EUROPEAN JOURNAL OF CARDIO-THORACIC SURGERY : OFFICIAL JOURNAL OF THE EUROPEAN ASSOCIATION FOR CARDIO-THORACIC SURGERY 2022; 63:6849520. [PMID: 36440952 DOI: 10.1093/ejcts/ezac539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 11/01/2022] [Indexed: 11/30/2022]
Abstract
OBJECTIVES During mitral valve replacement, the anterior mitral leaflet is usually resected or modified. Anterior leaflet splitting seems the least disruptive modification. Reattachment of the modified leaflet to the annulus reduces the annulopapillary distance. The goal of this study was to quantify the acute effects on left ventricular function of splitting the anterior mitral leaflet and shortening the annulopapillary distance. METHODS In 6 adult sheep, a wire was placed around the anterior leaflet and exteriorized through the left ventricular wall to enable splitting the leaflet in the beating heart. Releasable snares to reduce annulopapillary distance were likewise positioned and exteriorized. A mechanical mitral prosthesis was inserted to prevent mitral incompetence during external manipulations of the native valve. Instantaneous changes in left ventricular function were recorded before and after shortening the annulopapillary distance, then before and after splitting the anterior leaflet. RESULTS After splitting the anterior leaflet, preload recruitable stroke work, stroke work, stroke volume, cardiac output, left ventricular end systolic pressure and mean pressure were significantly decreased by 26%, 23%, 12%, 9%, 15% and 11%, respectively. Shortening the annulopapillary distance was associated with significant decreases in the end systolic pressure volume relationship, preload recruitable stroke work, stroke work and left ventricular end systolic pressure by 67%, 33%, 15% and 13%, respectively. Shortening the annulopapillary distance after splitting the leaflet had no significant effect. CONCLUSIONS Splitting the anterior mitral leaflet acutely impaired left ventricular contractility and haemodynamics in an ovine model. Shortening the annulopapillary distance after leaflet splitting did not further impair left ventricular function.
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Affiliation(s)
| | - Zoe A Williams
- DVC Research Portfolio, The University of Sydney, NSW, Australia
| | - Konstantin Yastrebov
- Prince of Wales Medical School, Faculty of Medicine and Health, The University of New South Wales, NSW, Australia
| | - Benjamin M Robinson
- Institute of Academic Surgery and Baird Institute for Applied Heart and Lung Surgery, Camperdown, NSW, Australia
| | - Innes K Wise
- Department of Laboratory Animal Services, The University of Sydney, NSW, Australia
| | - Hugh S Paterson
- Central Clinical School-Surgery, Faculty of Medicine and Health, The University of Sydney, NSW, Australia
| | - Paul G Bannon
- Institute of Academic Surgery and Baird Institute for Applied Heart and Lung Surgery, Camperdown, NSW, Australia.,Central Clinical School-Surgery, Faculty of Medicine and Health, The University of Sydney, NSW, Australia
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Cowie B, Costello B, Wright L, Janssens K, Howden E, Flannery D, Foulkes S, Kluger R, Gerche AL. Diastolic flow in the left ventricular outflow tract - A normal physiological and underappreciated echocardiographic finding. Australas J Ultrasound Med 2022; 25:137-141. [PMID: 35978728 PMCID: PMC9351428 DOI: 10.1002/ajum.12307] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/06/2023] Open
Abstract
PURPOSE Diastolic waveforms in the left ventricular outflow tract (LVOT) are commonly observed with Doppler echocardiography. The incidence and mechanism are not well described. METHODS This was a retrospective observational study of 186 adult patients, athletes and non-athletes, free of known cardiac disease, presenting for comprehensive transthoracic echocardiography at a research institute. We aimed to evaluate the incidence and echocardiographic associations between LVOT diastolic waveforms. RESULTS Left ventricular outflow tract early to mid-diastolic waveforms were present in 100% of athletes and 95% of non-athletes. The LVOT diastolic velocity time integral was larger in athletes than non-athletes with a mean 8.3 cm (95% CI (7.6-8.9)) vs. 5.1 cm (4.4-5.9) (P < 0.0001). Multivariate predictors of this diastolic waveform were age (P = 0.002), slower heart rate (P = 0.035), higher stroke volume (P = 0.003), large mitral E (P = 0.019) and higher E/e' (P = 0.015). DISCUSSION An LVOT early diastolic wave is a normal physiological finding. It is related to a flow vortex redirecting diastolic mitral inflow around anterior mitral valve leaflet into the LVOT. CONCLUSIONS Early to mid-diastolic LVOT waves are present in almost all patients but more prominent in young athletes than non-athletes. Diastolic LVOT waves increase with younger age, slower heart rate, larger stroke volume and enhanced diastolic function.
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Affiliation(s)
- Brian Cowie
- Sports Cardiology LaboratoryBaker Heart and Diabetes Institute75 Commerical RoadMelbourneVictoria3004Australia
- Department of AnaesthesiaSt. Vincent's Hospital, Melbourne41 Victoria ParadeFitzroyVictoria3065Australia
| | - Ben Costello
- Sports Cardiology LaboratoryBaker Heart and Diabetes Institute75 Commerical RoadMelbourneVictoria3004Australia
| | - Leah Wright
- Sports Cardiology LaboratoryBaker Heart and Diabetes Institute75 Commerical RoadMelbourneVictoria3004Australia
| | - Kristel Janssens
- Sports Cardiology LaboratoryBaker Heart and Diabetes Institute75 Commerical RoadMelbourneVictoria3004Australia
| | - Erin Howden
- Sports Cardiology LaboratoryBaker Heart and Diabetes Institute75 Commerical RoadMelbourneVictoria3004Australia
| | - Darragh Flannery
- Sports Cardiology LaboratoryBaker Heart and Diabetes Institute75 Commerical RoadMelbourneVictoria3004Australia
| | - Steve Foulkes
- Sports Cardiology LaboratoryBaker Heart and Diabetes Institute75 Commerical RoadMelbourneVictoria3004Australia
| | - Roman Kluger
- Department of AnaesthesiaSt. Vincent's Hospital, Melbourne41 Victoria ParadeFitzroyVictoria3065Australia
| | - Andre La Gerche
- Sports Cardiology LaboratoryBaker Heart and Diabetes Institute75 Commerical RoadMelbourneVictoria3004Australia
- Department of Cardiometabolic HealthUniversity of MelbourneParkvilleVictoria3010Australia
- National Centre for Sports CardiologySt. Vincent's Hospital, Melbourne41 Victoria ParardeFitzroyVictoria3065Australia
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8
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Alharbi Y, Al Abed A, Bakir AA, Lovell NH, Muller DWM, Otton J, Dokos S. Fluid structure computational model of simulating mitral valve motion in a contracting left ventricle. Comput Biol Med 2022; 148:105834. [PMID: 35816854 DOI: 10.1016/j.compbiomed.2022.105834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 06/24/2022] [Accepted: 07/04/2022] [Indexed: 11/17/2022]
Abstract
BACKGROUND Fluid structure interaction simulations h hold promise in studying normal and abnormal cardiac function, including the effect of fluid dynamics on mitral valve (MV) leaflet motion. The goal of this study was to develop a 3D fluid structure interaction computational model to simulate bileaflet MV when interacting with blood motion in left ventricle (LV). METHODS The model consists of ideal geometric-shaped MV leaflets and the LV, with MV dimensions based on human anatomical measurements. An experimentally-based hyperelastic isotropic material was used to model the mechanical behaviour of the MV leaflets, with chordae tendineae and papillary muscle tips also incorporated. LV myocardial tissue was prescribed using a transverse isotropic hyperelastic formulation. Incompressible Navier-Stokes fluid formulations were used to govern the blood motion, and the Arbitrary Lagrangian Eulerian (ALE) method was employed to determine the mesh deformation of the fluid and solid domains due to trans-valvular pressure on MV boundaries and the resulting leaflet movement. RESULTS The LV-MV generic model was able to reproduce physiological MV leaflet opening and closing profiles resulting from the time-varying atrial and ventricular pressures, as well as simulating normal and prolapsed MV states. Additionally, the model was able to simulate blood flow patterns after insertion of a prosthetic MV with and without left ventricular outflow tract flow obstruction. In the MV-LV normal model, the regurgitant blood flow fraction was 10.1 %, with no abnormality in cardiac function according to the mitral regurgitation severity grades reported by the American Society of Echocardiography. CONCLUSION Our simulation approach provides insights into intraventricular fluid dynamics in a contracting LV with normal and prolapsed MV function, as well as aiding in the understanding of possible complications after transcatheter MV implantation prior to clinical trials.
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Affiliation(s)
- Yousef Alharbi
- College of Applied Medical Sciences, Prince Sattam Bin Abdulaziz University, Al-Kharj, Saudi Arabia; Graduate School of Biomedical Engineering, University of New South Wales, Sydney, Australia.
| | - Amr Al Abed
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, Australia.
| | - Azam Ahmad Bakir
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, Australia; University of Southampton Malaysia Campus, Iskandar Puteri, Johor, Malaysia.
| | - Nigel H Lovell
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, Australia.
| | - David W M Muller
- Victor Chang Cardiac Research Institute, Sydney, Australia; Department of Cardiology and Cardiothoracic Surgery, St Vincent's Hospital, Sydney, Australia.
| | - James Otton
- Victor Chang Cardiac Research Institute, Sydney, Australia; Department of Cardiology, Liverpool Hospital, Sydney, Australia.
| | - Socrates Dokos
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, Australia.
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Toma M, Singh-Gryzbon S, Frankini E, Wei Z(A, Yoganathan AP. Clinical Impact of Computational Heart Valve Models. MATERIALS (BASEL, SWITZERLAND) 2022; 15:3302. [PMID: 35591636 PMCID: PMC9101262 DOI: 10.3390/ma15093302] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 04/26/2022] [Accepted: 04/29/2022] [Indexed: 12/17/2022]
Abstract
This paper provides a review of engineering applications and computational methods used to analyze the dynamics of heart valve closures in healthy and diseased states. Computational methods are a cost-effective tool that can be used to evaluate the flow parameters of heart valves. Valve repair and replacement have long-term stability and biocompatibility issues, highlighting the need for a more robust method for resolving valvular disease. For example, while fluid-structure interaction analyses are still scarcely utilized to study aortic valves, computational fluid dynamics is used to assess the effect of different aortic valve morphologies on velocity profiles, flow patterns, helicity, wall shear stress, and oscillatory shear index in the thoracic aorta. It has been analyzed that computational flow dynamic analyses can be integrated with other methods to create a superior, more compatible method of understanding risk and compatibility.
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Affiliation(s)
- Milan Toma
- Department of Osteopathic Manipulative Medicine, New York Institute of Technology College of Osteopathic Medicine, Northern Boulevard, P.O. Box 8000, Old Westbury, NY 11568, USA;
| | - Shelly Singh-Gryzbon
- Wallace H. Coulter School of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA; (S.S.-G.); (A.P.Y.)
| | - Elisabeth Frankini
- Department of Osteopathic Manipulative Medicine, New York Institute of Technology College of Osteopathic Medicine, Northern Boulevard, P.O. Box 8000, Old Westbury, NY 11568, USA;
| | - Zhenglun (Alan) Wei
- Department of Biomedical Engineering, Francis College of Engineering, University of Massachusetts Lowell, Lowell, MA 01854, USA;
| | - Ajit P. Yoganathan
- Wallace H. Coulter School of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA; (S.S.-G.); (A.P.Y.)
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10
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Govindarajan V, Kolanjiyil A, Johnson NP, Kim H, Chandran KB, McPherson DD. Improving transcatheter aortic valve interventional predictability via fluid-structure interaction modelling using patient-specific anatomy. ROYAL SOCIETY OPEN SCIENCE 2022; 9:211694. [PMID: 35154799 PMCID: PMC8826300 DOI: 10.1098/rsos.211694] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 01/04/2022] [Indexed: 05/03/2023]
Abstract
Transcatheter aortic valve replacement (TAVR) is now a standard treatment for high-surgical-risk patients with severe aortic valve stenosis. TAVR is being explored for broader indications including degenerated bioprosthetic valves, bicuspid valves and for aortic valve (AV) insufficiency. It is, however, challenging to predict whether the chosen valve size, design or its orientation would produce the most-optimal haemodynamics in the patient. Here, we present a novel patient-specific evaluation framework to realistically predict the patient's AV performance with a high-fidelity fluid-structure interaction analysis that included the patient's left ventricle and ascending aorta (AAo). We retrospectively evaluated the pre- and post-TAVR dynamics of a patient who underwent a 23 mm TAVR and evaluated against the patient's virtually de-calcified AV serving as a hypothetical benchmark. Our model predictions were consistent with clinical data. Stenosed AV produced a turbulent flow during peak-systole, while aortic flow with TAVR and de-calcified AV were both in the laminar-to-turbulent transitional regime with an estimated fivefold reduction in viscous dissipation. For TAVR, dissipation was highest during early systole when valve deformation was the greatest, suggesting that an efficient valve opening may reduce energy loss. Our study demonstrates that such patient-specific modelling frameworks can be used to improve predictability and in the planning of AV interventions.
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Affiliation(s)
- Vijay Govindarajan
- Division of Cardiology, Department of Internal Medicine, McGovern Medical School, The University of Texas Health Science at Houston, 1881 East Road, Houston, TX 77054, USA
| | - Arun Kolanjiyil
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Nils P. Johnson
- Division of Cardiology, Department of Internal Medicine, McGovern Medical School, The University of Texas Health Science at Houston, 1881 East Road, Houston, TX 77054, USA
| | - Hyunggun Kim
- Division of Cardiology, Department of Internal Medicine, McGovern Medical School, The University of Texas Health Science at Houston, 1881 East Road, Houston, TX 77054, USA
- Department of Bio-Mechatronic Engineering, Sungkyunkwan University, Suwon, Gyeonggi, Korea
| | - Krishnan B. Chandran
- Division of Cardiology, Department of Internal Medicine, McGovern Medical School, The University of Texas Health Science at Houston, 1881 East Road, Houston, TX 77054, USA
- Roy J. Carver Department of Biomedical Engineering, The University of Iowa, Iowa City, IA, USA
| | - David D. McPherson
- Division of Cardiology, Department of Internal Medicine, McGovern Medical School, The University of Texas Health Science at Houston, 1881 East Road, Houston, TX 77054, USA
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Alterations in Intracardiac Flow Patterns Affect Mitral Leaflets Dynamics in a Model of Ischemic Mitral Regurgitation. Cardiovasc Eng Technol 2021; 12:640-650. [PMID: 34467514 DOI: 10.1007/s13239-021-00567-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 07/19/2021] [Indexed: 10/20/2022]
Abstract
PURPOSE This study was to evaluate the effects of ischemic mitral regurgitation (IMR) on vortex formation and leaflet dynamics using an established porcine infarct model of IMR. METHODS Using direct coronary ligation, five animals were subjected to a posterolateral myocardial infarction (MI) followed by an MRI at 12-weeks post MI. MR imaging consisted of 4D time-resolved left ventricular (LV) flow, full coverage 2D LV cine, and high resolution 2D cine of mitral valve dynamics. Five additional naïve animals underwent identical imaging protocols to serve as controls. Image analysis was performed to obtain mitral transvalvular flows as well as LV volumes throughout the cardiac cycle. In addition, anterior to posterior mid-leaflet tip distances were measured throughout the cardiac cycle for determination of temporal leaflet dynamics. RESULTS It was found IMR caused asymmetric vortex ring formation with the anterior vortex having a lower vorticity relative to its posterior counterpart. In contrast, normal ventricles create symmetric and tightly curled vortices in the basal chamber just underneath the mitral leaflets which conserve kinetic energy and aid in effective ejection. IMR animals were also evaluated for leaflet separation and were found to have a greater leaflet opening and achieved peak vorticity and peak leaflet opening later than control animals. CONCLUSION In conclusion, this study shows the effects that altered vortex formation, due to IMR, can have on ventricular filling and leaflet dynamics. These findings have important implications for understanding blood flow through the dilated heart and how ring annuloplasty and volume reduction interventions may influence mitral valve dynamics.
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Age-Related Changes in Left Ventricular Vortex Formation and Flow Energetics. J Clin Med 2021; 10:jcm10163619. [PMID: 34441914 PMCID: PMC8397127 DOI: 10.3390/jcm10163619] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 07/29/2021] [Accepted: 08/03/2021] [Indexed: 11/26/2022] Open
Abstract
Analysis of the cardiac vortex has been used for a deeper understanding of the pathophysiology in heart diseases. However, physiological changes of the cardiac vortex with normal aging are incompletely defined. Vector flow mapping (VFM) is a novel echocardiographic technique based on Doppler and speckle tracking for analysis of the cardiac vortex. Transthoracic echocardiography and VFM analysis were performed in 100 healthy adults (33 men; age = 18–67 years). The intracardiac flow was assessed throughout the cardiac cycle. The size (cross-sectional area) and circulation (equivalent to the integral of normal component of vorticity) of the largest vortices in systole (S-vortex), early diastole (E-vortex), and late diastole (A-vortex) were measured. Peak energy loss (EL) was calculated from information of the velocity vector of intracardiac flow in systole and diastole. With normal aging, the circulation (p = 0.049) of the E-vortex decreased, while that of the A-vortex increased (both p < 0.001). E-vortex circulation correlated directly to e’ (p = 0.003), A-vortex circulation correlated directly to A and a’ (both p < 0.001), and S-vortex circulation correlated directly to s’ (p = 0.032). Despite changes in vortex patterns, energy loss was not significantly different in older individuals. Normal aging is associated with altered intracardiac vortex patterns throughout the cardiac cycle, with the late-diastolic A-vortex becoming physiologically more dominant. Maintained energy efficiency accompanies changes in vortex patterns in aging hearts.
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Khodaei S, Henstock A, Sadeghi R, Sellers S, Blanke P, Leipsic J, Emadi A, Keshavarz-Motamed Z. Personalized intervention cardiology with transcatheter aortic valve replacement made possible with a non-invasive monitoring and diagnostic framework. Sci Rep 2021; 11:10888. [PMID: 34035325 PMCID: PMC8149684 DOI: 10.1038/s41598-021-85500-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 02/12/2021] [Indexed: 02/04/2023] Open
Abstract
One of the most common acute and chronic cardiovascular disease conditions is aortic stenosis, a disease in which the aortic valve is damaged and can no longer function properly. Moreover, aortic stenosis commonly exists in combination with other conditions causing so many patients suffer from the most general and fundamentally challenging condition: complex valvular, ventricular and vascular disease (C3VD). Transcatheter aortic valve replacement (TAVR) is a new less invasive intervention and is a growing alternative for patients with aortic stenosis. Although blood flow quantification is critical for accurate and early diagnosis of C3VD in both pre and post-TAVR, proper diagnostic methods are still lacking because the fluid-dynamics methods that can be used as engines of new diagnostic tools are not well developed yet. Despite remarkable advances in medical imaging, imaging on its own is not enough to quantify the blood flow effectively. Moreover, understanding of C3VD in both pre and post-TAVR and its progression has been hindered by the absence of a proper non-invasive tool for the assessment of the cardiovascular function. To enable the development of new non-invasive diagnostic methods, we developed an innovative image-based patient-specific computational fluid dynamics framework for patients with C3VD who undergo TAVR to quantify metrics of: (1) global circulatory function; (2) global cardiac function as well as (3) local cardiac fluid dynamics. This framework is based on an innovative non-invasive Doppler-based patient-specific lumped-parameter algorithm and a 3-D strongly-coupled fluid-solid interaction. We validated the framework against clinical cardiac catheterization and Doppler echocardiographic measurements and demonstrated its diagnostic utility by providing novel analyses and interpretations of clinical data in eleven C3VD patients in pre and post-TAVR status. Our findings position this framework as a promising new non-invasive diagnostic tool that can provide blood flow metrics while posing no risk to the patient. The diagnostic information, that the framework can provide, is vitally needed to improve clinical outcomes, to assess patient risk and to plan treatment.
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Affiliation(s)
- Seyedvahid Khodaei
- grid.25073.330000 0004 1936 8227Department of Mechanical Engineering, McMaster University, Hamilton, ON L8S 4L7 Canada
| | - Alison Henstock
- grid.25073.330000 0004 1936 8227Department of Mechanical Engineering, McMaster University, Hamilton, ON L8S 4L7 Canada
| | - Reza Sadeghi
- grid.25073.330000 0004 1936 8227Department of Mechanical Engineering, McMaster University, Hamilton, ON L8S 4L7 Canada
| | - Stephanie Sellers
- grid.416553.00000 0000 8589 2327St. Paul’s Hospital, Vancouver, BC Canada ,grid.17091.3e0000 0001 2288 9830Department of Radiology, University of British Columbia, Vancouver, BC Canada
| | - Philipp Blanke
- grid.416553.00000 0000 8589 2327St. Paul’s Hospital, Vancouver, BC Canada ,grid.17091.3e0000 0001 2288 9830Department of Radiology, University of British Columbia, Vancouver, BC Canada
| | - Jonathon Leipsic
- grid.416553.00000 0000 8589 2327St. Paul’s Hospital, Vancouver, BC Canada ,grid.17091.3e0000 0001 2288 9830Department of Radiology, University of British Columbia, Vancouver, BC Canada
| | - Ali Emadi
- grid.25073.330000 0004 1936 8227Department of Mechanical Engineering, McMaster University, Hamilton, ON L8S 4L7 Canada ,grid.25073.330000 0004 1936 8227Department of Electrical and Computer Engineering, McMaster University, Hamilton, ON Canada
| | - Zahra Keshavarz-Motamed
- grid.25073.330000 0004 1936 8227Department of Mechanical Engineering, McMaster University, Hamilton, ON L8S 4L7 Canada ,grid.25073.330000 0004 1936 8227School of Biomedical Engineering, McMaster University, Hamilton, ON Canada ,grid.25073.330000 0004 1936 8227School of Computational Science and Engineering, McMaster University, Hamilton, ON Canada
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Lawrie G, Zoghbi W, Little S, Shah D, Earle N, Earle E. One Hundred Percent Reparability of Mitral Prolapse: Results of a Dynamic Nonresectional Technique. Ann Thorac Surg 2021; 112:1921-1928. [PMID: 33497666 DOI: 10.1016/j.athoracsur.2020.09.090] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 09/10/2020] [Accepted: 09/28/2020] [Indexed: 11/16/2022]
Abstract
BACKGROUND We studied the results of a dynamic mitral repair technique that preserves normal mitral valve function by avoiding leaflet resection and rigid and semirigid annuloplasty rings. METHODS In previous reports we demonstrated that intraoperative simulation of mitral valve locking and isovolumic systole by rapid left ventricular inflation with pressurized saline accurately simulates mitral annular and leaflet shape and position, and left ventricular outflow tract dimensions. Length of polytetrafluoroethylene neochordae and size of fully flexible adjustable annuloplasty ring can be adjusted in three dimensions for accurate apposition of zones of leaflet coaptation, premarked with dots. We followed 1068 consecutive patients after repairs performed between 2001 and 2018. RESULTS Of the 1068 patients, 674 were men (63.1%). Mean age was 62.25 ± 13 years. Leaflet repaired was anterior in 118 patients (11.05%), posterior in 564 (52.81%), both in 55 (5.15%), and neither in 123 (11.5%). Barlow's disease was present in 208 patients (19.48%). Repair was isolated in 82.5% (881 of 1068). Reparability was 100%. Perioperative mortality overall was 1.59% (17 of 1068): isolated repair, 1.14% (10 of 881); and isolated posterior leaflet, 0.85% (4 of 472). Leaflet systolic anterior motion occurred in 1.7% (18 of 1068), and was significant in 0.4% (4 of 1068). Survival at 10 years by Kaplan-Meier analysis was 74.65%, freedom from reoperation was 96.01%, and freedom from severe mitral regurgitation was 94%. The only predictor of reoperation (Cox analysis) was being male (P = .001). CONCLUSIONS Use of intraoperative simulation of mitral dynamics led to 100% reparability for degenerative valves with minimal systolic anterior motion, despite no leaflet resection. Long-term durability has been good and similar for all leaflets.
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Affiliation(s)
- Gerald Lawrie
- Department of Cardiovascular Surgery, Methodist DeBakey Heart Center, Houston Methodist Hospital, Houston, Texas.
| | - William Zoghbi
- Department of Cardiology, Methodist DeBakey Heart Center, Houston Methodist Hospital, Houston, Texas
| | - Stephen Little
- Department of Cardiology, Methodist DeBakey Heart Center, Houston Methodist Hospital, Houston, Texas
| | - Dipan Shah
- Department of Cardiology, Methodist DeBakey Heart Center, Houston Methodist Hospital, Houston, Texas
| | - Nan Earle
- Department of Cardiovascular Surgery, Methodist DeBakey Heart Center, Houston Methodist Hospital, Houston, Texas
| | - Elizabeth Earle
- Department of Cardiovascular Surgery, Methodist DeBakey Heart Center, Houston Methodist Hospital, Houston, Texas
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15
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Surgical treatment of mitral regurgitation. Curr Opin Cardiol 2020; 35:491-499. [PMID: 32740446 DOI: 10.1097/hco.0000000000000772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW Mitral repair is the best treatment for degenerative mitral regurgitation. Many patients are referred too late for optimal outcomes. The US repair vs. replacement rate is only 60-80%, at a time when the inferiority of replacement has been established. Therefore, widely used traditional techniques of repair are being reappraised. RECENT FINDINGS Identification of risk factors predictive of poor early and late outcome have improved timing for surgical referral. Composite risk scores have been developed. Novel echocardiographic, cardiac MRI, and molecular level risk factors could improve timing. Analysis of factors contributing to low repair rates is also of critical importance. The role of institutional and surgeon volumes have been identified. More detailed data on the importance of dynamic function of the mitral valve have led to improved repair techniques such as intraoperative simulation of end diastole and early systole, use of expanded polytetrafluoroethylene neochords instead of leaflet resection, and dynamic instead of rigid annuloplasty. SUMMARY Our perception of mitral regurgitation has changed from a seemingly simple condition to one of considerable complexity at multiple levels. National guidelines should be studied and followed.
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Hirschhorn M, Tchantchaleishvili V, Stevens R, Rossano J, Throckmorton A. Fluid–structure interaction modeling in cardiovascular medicine – A systematic review 2017–2019. Med Eng Phys 2020; 78:1-13. [DOI: 10.1016/j.medengphy.2020.01.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2019] [Revised: 01/18/2020] [Accepted: 01/26/2020] [Indexed: 01/06/2023]
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Biffi B, Gritti M, Grasso A, Milano EG, Fontana M, Alkareef H, Davar J, Jeetley P, Whelan C, Anderson S, Lorusso D, Sauvage E, Maria Bosi G, Schievano S, Capelli C. A workflow for patient-specific fluid-structure interaction analysis of the mitral valve: A proof of concept on a mitral regurgitation case. Med Eng Phys 2019; 74:153-161. [PMID: 31653498 DOI: 10.1016/j.medengphy.2019.09.020] [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: 01/28/2019] [Revised: 07/24/2019] [Accepted: 09/29/2019] [Indexed: 12/12/2022]
Abstract
The mechanics of the mitral valve (MV) are the result of the interaction of different anatomical structures complexly arranged within the left heart (LH), with the blood flow. MV structure abnormalities might cause valve regurgitation which in turn can lead to heart failure. Patient-specific computational models of the MV could provide a personalised understanding of MV mechanics, dysfunctions and possible interventions. In this study, we propose a semi-automatic pipeline for MV modelling based on the integration of state-of-the-art medical imaging, i.e. cardiac magnetic resonance (CMR) and 3D transoesophageal-echocardiogram (TOE) with fluid-structure interaction (FSI) simulations. An FSI model of a patient with MV regurgitation was implemented using the finite element (FE) method and smoothed particle hydrodynamics (SPH). Our study showed the feasibility of combining image information and computer simulations to reproduce patient-specific MV mechanics as seen on medical images, and the potential for efficient in-silico studies of MV disease, personalised treatments and device design.
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Affiliation(s)
- Benedetta Biffi
- Centre for Clinical Cardiovascular Engineering, UCL Institute of Cardiovascular Science & Great Ormond Street Hospital for Children, London, UK; Department of Medical Physics and Biomedical Engineering, University College London, London, UK.
| | - Maurizio Gritti
- The National Amyloidosis Centre, Division of Medicine, UCL Medical School, Royal Free Hospital, London, UK
| | - Agata Grasso
- Department of Cardiology, Royal Free Hospital, London, UK
| | - Elena G Milano
- Centre for Clinical Cardiovascular Engineering, UCL Institute of Cardiovascular Science & Great Ormond Street Hospital for Children, London, UK
| | - Marianna Fontana
- The National Amyloidosis Centre, Division of Medicine, UCL Medical School, Royal Free Hospital, London, UK
| | - Hamad Alkareef
- Centre for Clinical Cardiovascular Engineering, UCL Institute of Cardiovascular Science & Great Ormond Street Hospital for Children, London, UK
| | - Joseph Davar
- Department of Cardiology, Royal Free Hospital, London, UK
| | | | - Carol Whelan
- Department of Cardiology, Royal Free Hospital, London, UK
| | - Sarah Anderson
- The National Amyloidosis Centre, Division of Medicine, UCL Medical School, Royal Free Hospital, London, UK
| | - Donatella Lorusso
- The National Amyloidosis Centre, Division of Medicine, UCL Medical School, Royal Free Hospital, London, UK
| | - Emilie Sauvage
- Centre for Clinical Cardiovascular Engineering, UCL Institute of Cardiovascular Science & Great Ormond Street Hospital for Children, London, UK
| | - Giorgia Maria Bosi
- Centre for Clinical Cardiovascular Engineering, UCL Institute of Cardiovascular Science & Great Ormond Street Hospital for Children, London, UK
| | - Silvia Schievano
- Centre for Clinical Cardiovascular Engineering, UCL Institute of Cardiovascular Science & Great Ormond Street Hospital for Children, London, UK
| | - Claudio Capelli
- Centre for Clinical Cardiovascular Engineering, UCL Institute of Cardiovascular Science & Great Ormond Street Hospital for Children, London, UK
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Meschini V, Viola F, Verzicco R. Modeling mitral valve stenosis: A parametric study on the stenosis severity level. J Biomech 2019; 84:218-226. [PMID: 30661734 DOI: 10.1016/j.jbiomech.2019.01.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Revised: 12/11/2018] [Accepted: 01/02/2019] [Indexed: 11/29/2022]
Abstract
New computational techniques providing more accurate representation of human heart pathologies could help uncovering relevant physical phenomena and improve the outcome of medical therapies. In this framework, the present work describes an efficient computational model for the evaluation of the ventricular flow alteration in presence of mitral valve stenosis. The model is based on the direct numerical simulation of the Navier-Stokes equations two-way coupled with a structural solver for the left ventricle and mitral valve dynamics. The presence of mitral valve stenosis is mimicked by a single-parameter constraint acting on the kinematics of the mitral leaflets. Four different degrees of mitral valve stenosis are considered focusing on the hemodynamic alterations occurring in pathologic conditions. The mitral jet, generated during diastole, is seen to shrink and strengthen when the stenosis gets more severe. As a consequence, the kinetic energy of the flow, the tissues shear stresses, the transvalvular pressure drop and mitral regurgitation increase. It results that, as the stenosis severity level increases, the geometric and effective orifice areas decrease up to 50% with respect the normal case due to the reduced leaflets mobility and stronger blood acceleration during the diastolic phase. The modified intraventricular hemodynamics is also related to a stronger pressure gradient that, for severe stenosis, can be more than ten times larger than the healthy valve case. These computational results are fully consistent with the available clinical literature and open the way to the virtual assessment of surgical procedures and to the evaluation of prosthetic devices.
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Affiliation(s)
| | | | - Roberto Verzicco
- PoF Group, University of Twente, the Netherlands; Department of Industrial Engineering, University of Roma Tor Vergata, Italy
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