Modeling Of Electrophysiology And Simulation Of Myocardial Ischemia Based On Realistic Anatomical Data Of Human Heart

Myocardial ischemia is the foremost precursor of cardiac arrhythmias. During ischemia, the delivery of substrates, primarily oxygen, to the myocardium stops, causing metabolic changes which result in a progressive deterioration of the electric activity in the injured region and subsequently to a loss of function and ultimately pump failure. Although there are many researches on this topic, the functional effects of ischemia-induced electrical properties of cardiac cells on ventricular electrical wave conduction have not yet been clearly demonstrated. Thus it would be of great importance to study the cardiac electrical activity under ischemia and explain ECG waveform changes induced by ischemia using biophysically detailed cellular models with realistic anatomical geometry of human heart.In this paper, we develop a human ventricular cell and tissue model of ischemia, and simulate the ECGs on 2D human left ventricular tissue. The main contents are as follows.First, to reproduce the cardiac electrical activity, we adopt the TNNP model. TNNP model consists of all major ionic currents based on recent experimental data on human ventricular cell, which keeps a better balance between electrophysiological property and computational efficiency. To deal with the no-flux boundary conditions, we adopt the phase-field method to automatically handle the complex boundary conditions.Second, based on the TNNP model, we develop a human ventricular ischemic model, which taking into account three main pathophysiological components of ischemia: elevated extracellular potassium, acidosis, and anoxia. We simulate action potential propagations of endocardial, midmycardial and epicardial cells under ischemia and measure respective action potential duration.Third, electrophysiological behaviors in endocardial, epicardial, transmural ischemia are modeled and analyzed by comparing with experimental data. We quantify ECG waveform changes in pseudo-ECG and six chest lead ECGs, particularly ST and T-wave depression or elevation, under ischemia, which are simulated on the realistic human left ventricular tissue. The ventricular tissue comprises different transitional border zones, simulating the heterogeneity created by regional myocardial ischemia. Finally, the regularity of ECG waveform changes induced by ischemia is summarized.