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Tran P, Lau C, Joshi M, Kuehl M, Maddock H, Banerjee P. Exploring Changes in Myocyte Structure, Contractility, and Energetics From Mechanical Unloading in Patients With Heart Failure Undergoing Ventricular Assist Device Implantation: A Systematic Review and Meta-Analysis. Heart Lung Circ 2024:S1443-9506(24)00082-9. [PMID: 38704332 DOI: 10.1016/j.hlc.2024.01.039] [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: 09/17/2023] [Revised: 01/27/2024] [Accepted: 01/31/2024] [Indexed: 05/06/2024]
Abstract
AIMS Recent reports of myocardial recovery after mechanical unloading with left ventricular assist devices (LVADs) have challenged the prevailing notion that end-stage heart failure (HF) is irreversible. To improve our understanding of this phenomenon, we comprehensively analysed the structural, functional, and energetic changes in failing human cardiomyocytes after LVAD implantation. METHODS Based on a prospectively registered protocol (PROSPERO-CRD42022380214), 30 eligible studies were identified from 940 records with a pooled population of 648 patients predominantly with non-ischaemic cardiomyopathy. RESULTS LVAD led to a substantial regression in myocyte size similar to that of donor hearts (standardised mean difference, -1.29; p<0.001). The meta-regression analysis revealed that HF duration was a significant modifier on the changes in myocyte size. There were some suggestions of fibrosis reversal (-5.17%; p=0.009); however, this was insignificant after sensitivity analysis. Developed force did not improve in cardiac trabeculae (n=5 studies); however, non-physiological isometric contractions were tested. At the myocyte level (n=4 studies), contractile kinetics improved where the time-to-peak force reduced by 41.7%-50.7% and time to 50% relaxation fell by 47.4%-62.1% (p<0.05). Qualitatively, LVAD enhanced substrate utilisation and mitochondrial function (n=6 studies). Most studies were at a high risk of bias. CONCLUSION The regression of maladaptive hypertrophy, partial fibrosis reversal, and normalisation in metabolic pathways after LVAD may be a testament to the heart's remarkable plasticity, even in the advanced stages of HF. However, inconsistencies exist in force-generating capabilities. Using more physiological force-length work-loop assays, addressing the high risks of bias and clinical heterogeneity are crucial to better understand the phenomenon of reverse remodelling.
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Affiliation(s)
- Patrick Tran
- Centre for Health & Life Sciences, Coventry University, Coventry, UK; Cardiology Department, University Hospitals Coventry and Warwickshire NHS Trust, Coventry, UK.
| | - Clement Lau
- Cardiology Department, University Hospitals Coventry and Warwickshire NHS Trust, Coventry, UK
| | - Mithilesh Joshi
- Cardiology Department, University Hospitals Coventry and Warwickshire NHS Trust, Coventry, UK; Warwick Medical School, University of Warwick, Coventry, UK
| | - Michael Kuehl
- Cardiology Department, University Hospitals Coventry and Warwickshire NHS Trust, Coventry, UK; Warwick Medical School, University of Warwick, Coventry, UK
| | - Helen Maddock
- Centre for Health & Life Sciences, Coventry University, Coventry, UK
| | - Prithwish Banerjee
- Centre for Health & Life Sciences, Coventry University, Coventry, UK; Cardiology Department, University Hospitals Coventry and Warwickshire NHS Trust, Coventry, UK; Warwick Medical School, University of Warwick, Coventry, UK
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Garrett AS, Dowrick J, Taberner AJ, Han JC. Isolated cardiac muscle contracting against a real-time model of systemic and pulmonary cardiovascular loads. Am J Physiol Heart Circ Physiol 2023; 325:H1223-H1234. [PMID: 37712924 PMCID: PMC10907072 DOI: 10.1152/ajpheart.00272.2023] [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: 05/10/2023] [Revised: 09/01/2023] [Accepted: 09/08/2023] [Indexed: 09/16/2023]
Abstract
Isolated cardiac tissues allow a direct assessment of cardiac muscle function and enable precise control of experimental loading conditions. However, current experimental methods do not expose isolated tissues to the same contraction pattern and cardiovascular loads naturally experienced by the heart. In this study, we implement a computational model of systemic-pulmonary impedance that is solved in real time and imposed on contracting isolated rat muscle tissues. This systemic-pulmonary model represents the cardiovascular system as a lumped-parameter, closed-loop circuit. The tissues performed force-length work-loop contractions where the model output informed both the shortening and restretch phases of each work-loop. We compared the muscle mechanics and energetics associated with work-loops driven by the systemic-pulmonary model with that of a model-based loading method that only accounts for shortening. We obtained results that show simultaneous changes of afterload and preload or end-diastolic length of the muscle, as compared with the static, user-defined preload as in the conventional loading method. This feature allows assessment of muscle work output, heat output, and efficiency of contraction as functions of end-diastolic length. The results reveal the behavior of cardiac muscle as a pump source to achieve load-dependent work and efficiency outputs over a wider range of loads. This study offers potential applications of the model to investigate cardiac muscle response to hemodynamic coupling between systemic and pulmonary circulations in an in vitro setting.NEW & NOTEWORTHY We present the use of a "closed-loop" model of systemic and pulmonary circulations to apply, for the first time, real-time model-calculated preload and afterload to isolated cardiac muscle preparations. This method extends current experimental protocols where only afterload has been considered. The extension to include preload provides the opportunity to investigate ventricular muscle response to hemodynamic coupling and as a pump source across a wider range of cardiovascular loads.
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Affiliation(s)
- Amy S Garrett
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Jarrah Dowrick
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Andrew J Taberner
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
- Department of Engineering Science and Biomedical Engineering, The University of Auckland, Auckland, New Zealand
| | - June-Chiew Han
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
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Dowrick JM, Tran K, Garrett AS, Anderson AJ, Nielsen PMF, Taberner AJ, Han JC. Work-loop contractions reveal that the afterload-dependent time course of cardiac Ca 2+ transients is modulated by preload. J Appl Physiol (1985) 2022; 133:663-675. [PMID: 35771221 PMCID: PMC9762964 DOI: 10.1152/japplphysiol.00137.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Preload and afterload dictate the dynamics of the cyclical work-loop contraction that the heart undergoes in vivo. Cellular Ca2+ dynamics drive contraction, but the effects of afterload alone on the Ca2+ transient are inconclusive. To our knowledge, no study has investigated whether the putative afterload dependence of the Ca2+ transient is preload dependent. This study is designed to provide the first insight into the Ca2+ handling of cardiac trabeculae undergoing work-loop contractions, with the aim to examine whether the conflicting afterload dependency of the Ca2+ transient can be accounted for by considering preload under isometric and physiological work-loop contractions. Thus, we subjected ex vivo rat right-ventricular trabeculae, loaded with the fluorescent dye Fura-2, to work-loop contractions over a wide range of afterloads at two preloads while measuring stress, length changes, and Ca2+ transients. Work-loop control was implemented with a real-time Windkessel model to mimic the contraction patterns of the heart in vivo. We extracted a range of metrics from the measured steady-state twitch stress and Ca2+ transients, including the amplitudes, time courses, rates of rise, and integrals. Results show that parameters of stress were afterload and preload dependent. In contrast, the parameters associated with Ca2+ transients displayed a mixed dependence on afterload and preload. Most notably, its time course was afterload dependent, an effect augmented at the greater preload. This study reveals that the afterload dependence of cardiac Ca2+ transients is modulated by preload, which brings the study of Ca2+ transients during isometric contractions into question when aiming to understand physiological Ca2+ handling.NEW & NOTEWORTHY This study is the first examination of Ca2+ handling in trabeculae undergoing work-loop contractions. These data reveal that reducing preload diminishes the influence of afterload on the decay phase of the cardiac Ca2+ transient. This is significant as it reconciles inconsistencies in the literature regarding the influence of external loads on cardiac Ca2+ handling. Furthermore, these findings highlight discrepancies between Ca2+ handling during isometric and work-loop contractions in cardiac trabeculae operating at their optimal length.
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Affiliation(s)
- Jarrah M. Dowrick
- 1Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Kenneth Tran
- 1Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Amy S. Garrett
- 1Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Alex J. Anderson
- 1Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Poul M. F. Nielsen
- 1Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand,2Department of Engineering Science, University of Auckland, Auckland, New Zealand
| | - Andrew J. Taberner
- 1Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand,2Department of Engineering Science, University of Auckland, Auckland, New Zealand
| | - June-Chiew Han
- 1Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
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Garrett AS, Loiselle DS, Taberner AJ, Han JC. Slower shortening kinetics of cardiac muscle performing Windkessel work‑loops increases mechanical efficiency. Am J Physiol Heart Circ Physiol 2022; 323:H461-H474. [PMID: 35904884 DOI: 10.1152/ajpheart.00074.2022] [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] [Indexed: 11/22/2022]
Abstract
Conventional experimental methods for studying cardiac muscle in vitro often do not expose the tissue preparations to a mechanical impedance that resembles the in vivo hemodynamic impedance dictated by the arterial system. That is, the afterload in work‑loop contraction is conventionally simplified to be constant throughout muscle shortening, and at a magnitude arbitrarily defined. This conventional afterload does not capture the time‑varying interaction between the left ventricle and the arterial system. We have developed a contraction protocol for isolated tissue experiments that allows the afterload to be described within a Windkessel framework that captures the mechanics of the large arteries. We aim to compare the energy expenditure of cardiac muscle undergoing the two contraction protocols: conventional versus Windkessel loading. Isolated rat left‑ventricular trabeculae were subjected to the two force-length work‑loop contractions. Mechanical work and heat liberation were assessed, and mechanical efficiency quantified, over wide ranges of afterloads or peripheral resistances. Both extent of shortening and heat output were unchanged between protocols, but peak shortening velocity was 39.0 % lower and peak work output was 21.8 % greater when muscles contracted against the Windkessel afterload than against the conventional isotonic afterload. The greater work led to a 25.2 % greater mechanical efficiency. Our findings demonstrate that the mechanoenergetic performance of cardiac muscles in vitro may have been previously constrained by the conventional, arbitrary, loading method. A Windkessel loading protocol, by contrast, unleashes more cardiac muscle mechanoenergetic potential, where the slower shortening increases efficiency in performing mechanical work.
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Affiliation(s)
- Amy S Garrett
- Auckland Bioengineering Institute, The University of Auckland, New Zealand
| | - Denis S Loiselle
- Auckland Bioengineering Institute, The University of Auckland, New Zealand.,Department of Physiology, The University of Auckland, New Zealand
| | - Andrew J Taberner
- Auckland Bioengineering Institute, The University of Auckland, New Zealand.,Department of Engineering Science, The University of Auckland, New Zealand
| | - June-Chiew Han
- Auckland Bioengineering Institute, The University of Auckland, New Zealand
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Garrett AS, Loiselle DS, Han JC, Taberner AJ. Heat production in quiescent cardiac muscle is length, velocity and muscle dependent: Implications for active heat measurement. Exp Physiol 2021; 106:2445-2456. [PMID: 34605075 DOI: 10.1113/ep089800] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 09/29/2021] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? Intracellular energetic processes in quiescent cardiac muscle release 'basal' heat; during contraction, a much larger amount of 'active' heat is also produced. Previously, measurement challenges have constrained researchers to assume that basal heat rate remains constant during contraction and shortening. Is this assumption correct? What is the main finding and its importance? We show that basal heat rate is modulated by the extent and velocity of muscle shortening. Their relative contributions are muscle specific. We apply a method with which researchers can now disentangle, for each experiment, changes in basal heat from active heat production, providing more precise measures of the individual energetic processes underlying cardiac muscle contraction. ABSTRACT Separating the variations in cardiac basal heat rate from variations in active heat rate is necessary to determine cardiac muscle energy consumption accurately during the performance of active work. By developing a model of cardiac muscle basal heat rate, we aimed to investigate changes in basal heat rate when cardiac muscle performs work. Experiments were conducted on 10 isolated rat cardiac trabeculae subjected to both active (work-loops) and quiescent (length-change and velocity) interventions. Muscle force, length and heat output rate were measured simultaneously in a flow-through work-loop calorimeter. Quiescent muscle characteristics were used to parameterize muscle-specific models of change in basal heat rate, thereby to predict dynamic changes in basal heat rate during active work-loop contraction. Our data showed that the quiescent heat characteristics of cardiac muscle varied between samples, displaying dependence on both the extent and the rate of change in muscle length. We found a moderate correlation between muscle dimensions (cross-sectional area and volume) and the length-dependent basal heat parameter (P = 0.0330 and P = 0.0242, respectively), but no correlation with the velocity-dependent parameter. These findings lead us to conclude that the heat output of cardiac muscle at quiescence varies with both the extent and the velocity of shortening, to an extent that is muscle specific, and that this variation must be measured and accounted for in each specimen when assessing active energetics.
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Affiliation(s)
- Amy S Garrett
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Denis S Loiselle
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand.,Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - June-Chiew Han
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Andrew J Taberner
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand.,Department of Engineering Science, The University of Auckland, Auckland, New Zealand
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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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Garrett AS, Loiselle DS, Han JC, Taberner AJ. Compensating for changes in heart muscle resting heat production in a microcalorimeter. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2020; 2020:2557-2560. [PMID: 33018528 DOI: 10.1109/embc44109.2020.9175474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The heat production of cardiac muscle, determined by calorimetry, can be used as a measure of cardiac metabolism. However, heat produced while a muscle is actively-shortening, thereby performing force-length work, comprises both active and basal metabolic processes. In this paper, we present a method for post-experimental processing of calorimetric measurements of muscle heat production, that uncovers and compensates for the measured basal heat rate during work. In this method, the relationships between muscle length, velocity of length change and muscle heat output are coupled with a simulation of the measurement instrument, providing a model-based estimate of change of measured basal heat while the muscle is performing work. We demonstrate the use of this technique in an experiment conducted on a working cardiac muscle sample. The ability to identify the various components of heat release in these muscles provides useful insight into their mechanical and energetic capabilities.
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