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Tang J, Ren W, Liu Y, Gao H, Wang Y, Huang S. Effects of post-treatment electroacupuncture on ventricular monophasic action potential and cardiac function in a rat model of ischemia/reperfusion injury. Acupunct Med 2021; 40:89-98. [PMID: 34553613 DOI: 10.1177/09645284211039229] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND To determine the effects of post-treatment electroacupuncture (EA) on the electrophysiological properties of ventricular muscle in rats with ischemia/reperfusion (IR) injury. METHODS Male Sprague-Dawley (SD) rats were randomly assigned into sham-operated (SH), IR and IR + EA groups (n = 8 each). The IR model was generated by ligation of the left anterior descending (LAD) coronary artery for 30 min. After establishing the IR model, EA was administered at PC6 for 30 min while opening the coronary artery and allowing reperfusion for 30 min. Heart rate (HR), mean arterial pressure and monophasic action potential (MAP) of cardiac muscle in the outer membrane of the antetheca of the left ventricle before coronary artery ligation (T0), after coronary artery ligation for 30 min (T1) and after reperfusion for 30 min (T2) were recorded. At the same time, ventricular electrophysiological parameters including ventricular effective refractory period (ERP), conduction velocity (CV) and ventricular fibrillation threshold (VFT) were measured. Then, the cardiac function and the levels of creatine kinase-muscle/brain (CK-MB) and cardiac troponin I (cTnI) were monitored. Based on these data, monophasic action potential amplitude (MAPA), the maximum depolarization velocity (Vmax) and the MAP durations at 50% and 90% repolarization (MAPD50 and MAPD90) were calculated to determine the incidence of arrhythmia during reperfusion. RESULTS Compared with the SH group, the IR group showed an obviously decreased HR as well as reduced mean arterial pressure, Vmax, CV, ERP and MAPA. All indices of cardiac function except left ventricular end-diastolic pressure (LVEDP) decreased (i.e. ventricular systolic pressure (LVSP), left ventricular ejection fraction (LVEF), fractional shortening (FS) and rate of the ventricular pressure rise/drop (±dp/dt)). Furthermore, the MAPD50 and MAPD90 were prolonged, and the levels of CK-MB and cTnI increased (p < 0.05). In comparison to the IR group, HR and the mean arterial pressure were increased. All indices of cardiac function except LVEDP increased (LVSP, LVEF, FS and ±dp/dt). Vmax, CV, ERP and MAPA were also increased in the IR + EA group. However, MAPD50 and MAPD90 were distinctly shortened, and the levels of CK-MB and cTnI decreased (p < 0.05). There were no statistically significant differences in VFT between the three groups (p > 0.05). CONCLUSION EA post-treatment can relieve prolongation of repolarization and slowed depolarization of ventricular muscle during IR, thus decreasing the rate of incidence of reperfusion arrhythmia.
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Affiliation(s)
- Jian Tang
- Department of Anesthesiology, The First Affiliated Hospital of Guizhou University of Traditional Chinese Medicine, Guiyang, China
| | - Wenxin Ren
- Department of Anesthesiology, Guizhou Medical University, Guiyang, China
| | - Yanqiu Liu
- Department of Anesthesiology, The Fourth People's Hospital of Guiyang, Guiyang, China
| | - Hong Gao
- Department of Anesthesiology, No. 3 Affiliated Hospital of Guizhou Medical University, Duyun, China
| | - Yuanliang Wang
- Department of Surgical, Universität Heidelberg, Heidelberg, Germany
| | - Suisui Huang
- Department of Anesthesiology, Guizhou Medical University, Guiyang, China
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The precision of macroscale mechanical measurements is limited by the inherent structural heterogeneity of human stratum corneum. Acta Biomater 2021; 130:308-316. [PMID: 34087446 DOI: 10.1016/j.actbio.2021.05.035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 05/18/2021] [Accepted: 05/20/2021] [Indexed: 12/18/2022]
Abstract
Biological tissues are structurally heterogenous mosaics at cellular and sub-cellular length scales. Some tissues, like the outermost layer of human skin, or stratum corneum (SC), also exhibit a rich topography of microchannels at larger mesoscopic length scales. Although this is well understood, modern studies continue to characterize the mechanical properties of biological tissues, including the SC, using macroscale techniques that assume these materials are homogenous in structure, thickness, and composition. Macroscale failure testing of SC is commonly associated with large sample to sample variability. We anticipate that microscale heterogeneities play an important role in defining the global mechanical response of the tissue. To evaluate the validity of the prevailing paradigm that macroscopic testing techniques can provide meaningful information about failure in soft heterogenous tissues, the macroscale work of fracture in isolated human SC samples is measured using conventional macroscale testing techniques and compared with the energy cost of creating new crack interfaces at the microscale, measured using a modified traction force microscopy technique. Results show that measured micro- and macroscale energy costs per unit crack path length are highly consistent. However, crack propagation is found to be guided by microscale topographical features in the tissue. This correlation reveals that macroscale mechanical sample to sample variability is caused by notable differences in crack propagation pathways. STATEMENT OF SIGNIFICANCE: Although designed to test homogeneous materials, macroscopic uniaxial tensometry is currently the gold standard for measuring the mechanical properties of biological tissues. All tissues, including human stratum corneum are structurally heterogeneous at the microscale and mechanical measurements are commonly highly variable, even for specimens from the same source. This study explores the fundamental causes of this disparity and evaluates the prevailing paradigm that macroscopic testing techniques can provide meaningful information about failure in soft heterogeneous tissues. Results conclude that the cause of large variability in mechanical work of fracture is due to inherent structural heterogeneities governing crack propagation pathways and altering the total crack length. Structural heterogeneities in tissue therefore limits the precision of macroscale biomechanical testing.
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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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In-silico human electro-mechanical ventricular modelling and simulation for drug-induced pro-arrhythmia and inotropic risk assessment. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2020; 159:58-74. [PMID: 32710902 PMCID: PMC7848595 DOI: 10.1016/j.pbiomolbio.2020.06.007] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 06/08/2020] [Accepted: 06/28/2020] [Indexed: 12/28/2022]
Abstract
Human-based computational modelling and simulation are powerful tools to accelerate the mechanistic understanding of cardiac patho-physiology, and to develop and evaluate therapeutic interventions. The aim of this study is to calibrate and evaluate human ventricular electro-mechanical models for investigations on the effect of the electro-mechanical coupling and pharmacological action on human ventricular electrophysiology, calcium dynamics, and active contraction. The most recent models of human ventricular electrophysiology, excitation-contraction coupling, and active contraction were integrated, and the coupled models were calibrated using human experimental data. Simulations were then conducted using the coupled models to quantify the effects of electro-mechanical coupling and drug exposure on electrophysiology and force generation in virtual human ventricular cardiomyocytes and tissue. The resulting calibrated human electro-mechanical models yielded active tension, action potential, and calcium transient metrics that are in agreement with experiments for endocardial, epicardial, and mid-myocardial human samples. Simulation results correctly predicted the inotropic response of different multichannel action reference compounds and demonstrated that the electro-mechanical coupling improves the robustness of repolarisation under drug exposure compared to electrophysiology-only models. They also generated additional evidence to explain the partial mismatch between in-silico and in-vitro experiments on drug-induced electrophysiology changes. The human calibrated and evaluated modelling and simulation framework constructed in this study opens new avenues for future investigations into the complex interplay between the electrical and mechanical cardiac substrates, its modulation by pharmacological action, and its translation to tissue and organ models of cardiac patho-physiology.
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Levrero-Florencio F, Margara F, Zacur E, Bueno-Orovio A, Wang Z, Santiago A, Aguado-Sierra J, Houzeaux G, Grau V, Kay D, Vázquez M, Ruiz-Baier R, Rodriguez B. Sensitivity analysis of a strongly-coupled human-based electromechanical cardiac model: Effect of mechanical parameters on physiologically relevant biomarkers. COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING 2020; 361:112762. [PMID: 32565583 PMCID: PMC7299076 DOI: 10.1016/j.cma.2019.112762] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The human heart beats as a result of multiscale nonlinear dynamics coupling subcellular to whole organ processes, achieving electrophysiologically-driven mechanical contraction. Computational cardiac modelling and simulation have achieved a great degree of maturity, both in terms of mathematical models of underlying biophysical processes and the development of simulation software. In this study, we present the detailed description of a human-based physiologically-based, and fully-coupled ventricular electromechanical modelling and simulation framework, and a sensitivity analysis focused on its mechanical properties. The biophysical detail of the model, from ionic to whole-organ, is crucial to enable future simulations of disease and drug action. Key novelties include the coupling of state-of-the-art human-based electrophysiology membrane kinetics, excitation-contraction and active contraction models, and the incorporation of a pre-stress model to allow for pre-stressing and pre-loading the ventricles in a dynamical regime. Through high performance computing simulations, we demonstrate that 50% to 200% - 1000% variations in key parameters result in changes in clinically-relevant mechanical biomarkers ranging from diseased to healthy values in clinical studies. Furthermore mechanical biomarkers are primarily affected by only one or two parameters. Specifically, ejection fraction is dominated by the scaling parameter of the active tension model and its scaling parameter in the normal direction ( k ort 2 ); the end systolic pressure is dominated by the pressure at which the ejection phase is triggered ( P ej ) and the compliance of the Windkessel fluid model ( C ); and the longitudinal fractional shortening is dominated by the fibre angle ( ϕ ) and k ort 2 . The wall thickening does not seem to be clearly dominated by any of the considered input parameters. In summary, this study presents in detail the description and implementation of a human-based coupled electromechanical modelling and simulation framework, and a high performance computing study on the sensitivity of mechanical biomarkers to key model parameters. The tools and knowledge generated enable future investigations into disease and drug action on human ventricles.
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Affiliation(s)
- F. Levrero-Florencio
- Department of Computer Science, University of Oxford, Oxford OX1 3QD, United Kingdom
- Corresponding authors.
| | - F. Margara
- Department of Computer Science, University of Oxford, Oxford OX1 3QD, United Kingdom
| | - E. Zacur
- Department of Engineering Science, University of Oxford, Oxford OX3 7DQ, United Kingdom
| | - A. Bueno-Orovio
- Department of Computer Science, University of Oxford, Oxford OX1 3QD, United Kingdom
| | - Z.J. Wang
- Department of Computer Science, University of Oxford, Oxford OX1 3QD, United Kingdom
| | - A. Santiago
- Barcelona Supercomputing Center – Centro Nacional de Supercomputación, Barcelona 08034, Spain
| | - J. Aguado-Sierra
- Barcelona Supercomputing Center – Centro Nacional de Supercomputación, Barcelona 08034, Spain
| | - G. Houzeaux
- Barcelona Supercomputing Center – Centro Nacional de Supercomputación, Barcelona 08034, Spain
| | - V. Grau
- Department of Engineering Science, University of Oxford, Oxford OX3 7DQ, United Kingdom
| | - D. Kay
- Department of Computer Science, University of Oxford, Oxford OX1 3QD, United Kingdom
| | - M. Vázquez
- Barcelona Supercomputing Center – Centro Nacional de Supercomputación, Barcelona 08034, Spain
- ELEM Biotech, Spain
| | - R. Ruiz-Baier
- Mathematical Institute, University of Oxford, Oxford OX2 6GG, United Kingdom
- Universidad Adventista de Chile, Casilla 7-D, Chillan, Chile
| | - B. Rodriguez
- Department of Computer Science, University of Oxford, Oxford OX1 3QD, United Kingdom
- Corresponding authors.
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