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Green L, Chan WX, Tulzer A, Tulzer G, Yap CH. Myocardial biomechanical effects of fetal aortic valvuloplasty. Biomech Model Mechanobiol 2024; 23:1433-1448. [PMID: 38683446 PMCID: PMC11436463 DOI: 10.1007/s10237-024-01848-0] [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: 10/23/2023] [Accepted: 04/07/2024] [Indexed: 05/01/2024]
Abstract
Fetal critical aortic stenosis with evolving hypoplastic left heart syndrome (CAS-eHLHS) can progress to a univentricular (UV) birth malformation. Catheter-based fetal aortic valvuloplasty (FAV) can resolve stenosis and reduce the likelihood of malformation progression. However, we have limited understanding of the biomechanical impact of FAV and subsequent LV responses. Therefore, we performed image-based finite element (FE) modeling of 4 CAS-eHLHS fetal hearts, by performing iterative simulations to match image-based characteristics and then back-computing physiological parameters. We used pre-FAV simulations to conduct virtual FAV (vFAV) and compared pre-FAV and post-FAV simulations. vFAV simulations generally enabled partial restoration of several physiological features toward healthy levels, including increased stroke volume and myocardial strains, reduced aortic valve (AV) and mitral valve regurgitation (MVr) velocities, reduced LV and LA pressures, and reduced peak myofiber stress. FAV often leads to aortic valve regurgitation (AVr). Our simulations showed that AVr could compromise LV and LA depressurization but it could also significantly increase stroke volume and myocardial deformational stimuli. Post-FAV scans and simulations showed FAV enabled only partial reduction of the AV dissipative coefficient. Furthermore, LV contractility and peripheral vascular resistance could change in response to FAV, preventing decreases in AV velocity and LV pressure, compared with what would be anticipated from stenosis relief. This suggested that case-specific post-FAV modeling is required to fully capture cardiac functionality. Overall, image-based FE modeling could provide mechanistic details of the effects of FAV, but computational prediction of acute outcomes was difficult due to a patient-dependent physiological response to FAV.
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Affiliation(s)
- Laura Green
- Department of Biomedical Engineering, Imperial College London, L2 Bessemer Building, South Kensington Campus, London, SW7 2AZ, UK
| | - Wei Xuan Chan
- Department of Biomedical Engineering, Imperial College London, L2 Bessemer Building, South Kensington Campus, London, SW7 2AZ, UK
- BHF Centre of Research Excellence, Imperial College London, London, UK
| | - Andreas Tulzer
- Department of Pediatric Cardiology, Children's Heart Center Linz, Kepler University Hospital, Linz, Austria
- Medical Faculty, Johannes Kepler University Linz, Altenberger Strasse 69, 4040, Linz, Austria
| | - Gerald Tulzer
- Department of Pediatric Cardiology, Children's Heart Center Linz, Kepler University Hospital, Linz, Austria
- Medical Faculty, Johannes Kepler University Linz, Altenberger Strasse 69, 4040, Linz, Austria
| | - Choon Hwai Yap
- Department of Biomedical Engineering, Imperial College London, L2 Bessemer Building, South Kensington Campus, London, SW7 2AZ, UK.
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Ahmed DW, Eiken MK, DePalma SJ, Helms AS, Zemans RL, Spence JR, Baker BM, Loebel C. Integrating mechanical cues with engineered platforms to explore cardiopulmonary development and disease. iScience 2023; 26:108472. [PMID: 38077130 PMCID: PMC10698280 DOI: 10.1016/j.isci.2023.108472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2024] Open
Abstract
Mechanical forces provide critical biological signals to cells during healthy and aberrant organ development as well as during disease processes in adults. Within the cardiopulmonary system, mechanical forces, such as shear, compressive, and tensile forces, act across various length scales, and dysregulated forces are often a leading cause of disease initiation and progression such as in bronchopulmonary dysplasia and cardiomyopathies. Engineered in vitro models have supported studies of mechanical forces in a number of tissue and disease-specific contexts, thus enabling new mechanistic insights into cardiopulmonary development and disease. This review first provides fundamental examples where mechanical forces operate at multiple length scales to ensure precise lung and heart function. Next, we survey recent engineering platforms and tools that have provided new means to probe and modulate mechanical forces across in vitro and in vivo settings. Finally, the potential for interdisciplinary collaborations to inform novel therapeutic approaches for a number of cardiopulmonary diseases are discussed.
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Affiliation(s)
- Donia W. Ahmed
- Department of Biomedical Engineering, University of Michigan, Lurie Biomedical Engineering Building, 1101 Beal Avenue, Ann Arbor, MI 48109, USA
| | - Madeline K. Eiken
- Department of Biomedical Engineering, University of Michigan, Lurie Biomedical Engineering Building, 1101 Beal Avenue, Ann Arbor, MI 48109, USA
| | - Samuel J. DePalma
- Department of Biomedical Engineering, University of Michigan, Lurie Biomedical Engineering Building, 1101 Beal Avenue, Ann Arbor, MI 48109, USA
| | - Adam S. Helms
- Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, MI 48109, USA
| | - Rachel L. Zemans
- Department of Internal Medicine, Division of Pulmonary Sciences and Critical Care Medicine – Gastroenterology, University of Michigan, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA
| | - Jason R. Spence
- Department of Internal Medicine – Gastroenterology, University of Michigan, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA
| | - Brendon M. Baker
- Department of Biomedical Engineering, University of Michigan, Lurie Biomedical Engineering Building, 1101 Beal Avenue, Ann Arbor, MI 48109, USA
| | - Claudia Loebel
- Department of Biomedical Engineering, University of Michigan, Lurie Biomedical Engineering Building, 1101 Beal Avenue, Ann Arbor, MI 48109, USA
- Department of Materials Science & Engineering, University of Michigan, North Campus Research Complex, 2800 Plymouth Road, Ann Arbor, MI 48109, USA
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Zhang D, Lindsey SE. Recasting Current Knowledge of Human Fetal Circulation: The Importance of Computational Models. J Cardiovasc Dev Dis 2023; 10:240. [PMID: 37367405 PMCID: PMC10299027 DOI: 10.3390/jcdd10060240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2023] [Revised: 05/16/2023] [Accepted: 05/23/2023] [Indexed: 06/28/2023] Open
Abstract
Computational hemodynamic simulations are becoming increasingly important for cardiovascular research and clinical practice, yet incorporating numerical simulations of human fetal circulation is relatively underutilized and underdeveloped. The fetus possesses unique vascular shunts to appropriately distribute oxygen and nutrients acquired from the placenta, adding complexity and adaptability to blood flow patterns within the fetal vascular network. Perturbations to fetal circulation compromise fetal growth and trigger the abnormal cardiovascular remodeling that underlies congenital heart defects. Computational modeling can be used to elucidate complex blood flow patterns in the fetal circulatory system for normal versus abnormal development. We present an overview of fetal cardiovascular physiology and its evolution from being investigated with invasive experiments and primitive imaging techniques to advanced imaging (4D MRI and ultrasound) and computational modeling. We introduce the theoretical backgrounds of both lumped-parameter networks and three-dimensional computational fluid dynamic simulations of the cardiovascular system. We subsequently summarize existing modeling studies of human fetal circulation along with their limitations and challenges. Finally, we highlight opportunities for improved fetal circulation models.
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Affiliation(s)
| | - Stephanie E. Lindsey
- Department of Mechanical and Aerospace Engineering, University of California, San Diego, CA 92093, USA;
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Fluid Mechanical Effects of Fetal Aortic Valvuloplasty for Cases of Critical Aortic Stenosis with Evolving Hypoplastic Left Heart Syndrome. Ann Biomed Eng 2023:10.1007/s10439-023-03152-x. [PMID: 36780051 DOI: 10.1007/s10439-023-03152-x] [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: 09/28/2022] [Accepted: 01/16/2023] [Indexed: 02/14/2023]
Abstract
Fetuses with critical aortic stenosis (FAS) are at high risk of progression to HLHS by the time of birth (and are thus termed "evolving HLHS"). An in-utero catheter-based intervention, fetal aortic valvuloplasty (FAV), has shown promise as an intervention strategy to circumvent the progression, but its impact on the heart's biomechanics is not well understood. We performed patient-specific computational fluid dynamic (CFD) simulations based on 4D fetal echocardiography to assess the changes in the fluid mechanical environment in the FAS left ventricle (LV) directly before and 2 days after FAV. Echocardiograms of five FAS cases with technically successful FAV were retrospectively analysed. FAS compromised LV stroke volume and ejection fraction, but FAV rescued it significantly. Calculations to match simulations to clinical measurements showed that FAV approximately doubled aortic valve orifice area, but it remained much smaller than in healthy hearts. Diseased LVs had mildly stenotic mitral valves, which generated fast and narrow diastolic mitral inflow jet and vortex rings that remained unresolved directly after FAV. FAV further caused aortic valve damage and high-velocity regurgitation. The high-velocity aortic regurgitation jet and vortex ring caused a chaotic flow field upon impinging the apex, which drastically exacerbated the already high energy losses and poor flow energy efficiency of FAS LVs. Two days after the procedure, FAV did not alter wall shear stress (WSS) spatial patterns of diseased LV but elevated WSS magnitudes, and the poor blood turnover in pre-FAV LVs did not significantly improve directly after FAV. FAV improved FAS LV's flow function, but it also led to highly chaotic flow patterns and excessively high energy losses due to the introduction of aortic regurgitation directly after the intervention. Further studies analysing the effects several weeks after FAV are needed to understand the effects of such biomechanics on morphological development.
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