| dc.description.abstract | In the past 15 years, ischemic heart disease is one of the world’s biggest killers. According to statistics from the World Health Organization in 2016, 10 million deaths were caused by it. This is not only due to the damage caused by coronary artery occlusion, but also many complications of myocardial ischemia including ventricular arrhythmia, cardiac arrest, atrioventricular block, and even heart failure and sudden cardiac death. Although these complications will cause serious damage, it can be prevented by early revascularization such as percutaneous coronary intervention (PCI), placing vascular stents, or thrombolytic agents. However, several clinical examination methods for diagnosing ischemia, such as single photon emission computed tomography and cardiac catheterization, may have many potential shortcomings, including low accuracy, high expense, time consumption, intrusive, the need of injection of radiocontrast agent, the problem of long-term monitoring, and the difficulty of reproducibility. Moreover, the gold standard examination method lacks of the abilities of remote home monitoring, rapid screening, and early diagnosis. In view of this market demand, the 12-lead electrocardiogram (ECG), which is commonly used to monitor the cardiac electrical activity, was selected and used for the diagnosis of myocardial ischemia. Besides, in the existing researches, the 12-lead ECG signals utilized to identify myocardial ischemia has achieved good accuracy. However, the localization of ischemia based on 12-lead ECG has not been practiced.
In clinic, myocardial ischemia and infarction will cause abnormalities to the waveform of myocardial cells’ transmembrane potentials (TMPs) in that region, including delayed activation time, reduced activation potential, rising resting potential, and reduced activation interval. These abnormal TMPs will increase the gradient of repolarized potentials in the ischemic region, and lead to the elevation or depression of the amplitude of ST segments and T waves, and even the inversion of T waves. Accordingly, based on this phenomenon of the electrophysiological mechanism, this study established a realistic ventricle-thorax anisotropic computer model to simulate the real-world electrical pacing of cardiac. By modifying the waveform of TMPs in different regions with various degrees of modification, we could simulate all possible ischemic regions and severity corresponding to real-world patients. Through forward calculation, we could calculate the 12-lead ECG signals from the ischemic cardiac potentials and established a massive 12-lead ECG ischemia database. The realistic computer cardiac model combined with a robust sparse representation classification algorithm was applied to 143 patients with myocardial infarction, and the accuracy of locating myocardial infarction could reach 0.91. Finally, we projected the severity and ischemic region from ventricular model into a 2D circular plane, which could visually display the perfusion of myocardial cells and improve the ability of 12-lead ECG to diagnose myocardial infarction. | en_US |