The effect of electrical conductivity of myocardium on cardiac pumping efficacy: a computational study

Abstract

Background and aims The existence of non-excitable cells in the myocardium leads to the increasing conduction non-uniformity and decreasing myocardial electrical conductivity. Slowed myocardial conduction velocity (MCV) believed to enhance the probability of cardiac arryhthmia and alter the cardiac mechanical pumping efficacy, even in sinus rhythm. Though several studies on the correlation between MCV and cardiac electrical instabilities exist, there has been no study concerning correlation or causality between MCV and cardiac mechanical pumping efficacy, due to the limitation in clinical methods to document and evaluate cardiac mechanical responses directly. The goal of this study was to examine quantitatively the cardiac pumping efficacy under various MCV conditions using three-dimensional (3D) electromechanical model of canine’s failing ventricle.Methods The electromechanical model used in this study composed of the electrical model coupled with the mechanical contraction model along with a lumped model of the circulatory system. The electrical model consisted of 241,725 nodes and 1,298,751 elements of tetrahedral mesh, whereas the mechanical model consisted of 356 nodes and 172 elements of hexahedral mesh with Hermite basis. First, we performed the electrical simulation for five different MCV conditions, from 30 to 70 cm/s with 10 cm/s interval during sinus pacing. Then, we compared the cardiac electrical and mechanical responses of each MCV condition, such as the electrical activation time (EAT), pressure, volume, and energy consumption of the myocardium. The energy consumption of the myocardium was calculated by integrating ATP consumption rate of each node in myofilament model.ResultsThe result showed that under higher MCV conditions, the EAT, energy consumption, end diastolic and systolic volume are gradually decreased. Meanwhile, the systolic pressure, stroke volume, stroke work, and stroke work to ATP are increased as the MCV values increased. The cardiac functions and performances are more efficient under higher MCV conditions by consuming smaller energy (ATP) while carrying more works.ConclusionIn conclusion, this study reveals that MCV has strong correlation with the cardiac pumping efficacy. The obtained results provide useful information to estimate the effect of MCV on the electro-physiology and hemodynamic responses of the ventricle and can be used for further study about arrhythmogeneis and heart failure.

Impact of Decreased Transmural Conduction Velocity on the Function of the Human Left Ventricle: A Simulation Study

“…The described effects are fully consistent with the recent work by Yuniarti and Lim [7] presenting simulations based on an electromechanical model of canine heart coupled with a lumped model of circulatory system. Their results also showed an increase in the electrical activation time (equivalent to IVCD) and in end-systolic volume with reduction of the CV, while systolic pressure, stroke volume, and stroke work decreased rather moderately.…”

“…An attempt to quantify the effect of CV reduction on mechanical response of the mammalian heart and basic hemodynamic parameters was undertaken recently by Yuniarti and Lim [7]. In their simulations using an integrated electromechanical model of the LV, the CV correlated with cardiac pumping efficacy.…”

Development of a bio‐MEMS device for electrical and mechanical conditioning and characterization of cell sheets for myocardial repair

“…(Hashitani, Fukuta, Takano, Klemm, & Suzuki, 2001); low velocity may be because of immature connections between cells in culture as testing was done only 1 day after seeding. Both batches of iPS-CMs had significantly higher measured conduction velocities as compared with the reference BVSMCs, but also measured much lower than documented in the literature (25-50 cm/s; Radisic & Christman, 2013;Yuniarti & Lim, 2017). Again, this is hypothesized to be because of short term culture on the device, imperfect alignment, and the lack of mature ion channel connections between cells.…”

Computational analysis of the electromechanical performance of mitral valve cerclage annuloplasty using a patient-specific ventricular model

“…Considering the many difficulties in performing an experimental or a clinical study using a living heart, computer simulation can be an alternative method to understand the physiological mechanism of MVCA treatment. Until now, computer simulation of cardiac electrophysiology and mechanics has been considered a significant tool for the investigation of the heart disease mechanism and for the development of novel therapeutic clinical techniques for heart diseases [567]. For example, multiscale heart modeling was developed by integrating cell, tissue, and organ scales to investigate the electrophysiological behavior of the heart [89101112].…”

“…For example, multiscale heart modeling was developed by integrating cell, tissue, and organ scales to investigate the electrophysiological behavior of the heart [89101112]. However, most of the computational studies on the mechanism of heart disease have been performed not on a patient-specific model, but rather on a typical cardiac model [5678910]. On the other hand, in the case of MVCA simulation, a patient-specific model is inevitable because tightening of mitral circumference can vary depending on the patient.…”