Description

Cardiovascular disease (CVD) is the leading cause of death worldwide. Most individuals with CVD show no evidence of disease for decades as the disease progresses before the first onset of symptoms, often a "sudden" heart attack, finally arises. The spatial repolarization heterogeneity within the ventricular myocardium had been proposed to represent the function of the heart in health and disease. Greater than normal levels of repolarization dispersion may allow early diagnosis of CVD. There is a growing interest in the characteristic features of ventricular repolarization that leads to lethal ventricular arrhythmia even with the use of non-antiarrhythmic drugs. The recovery time dispersion may reflect a repolarization heterogeneity leading to lethal ventricular arrhythmia. Although cheap and convenient, the traditional 12-leads electrocardiogram (ECG) is frequently normal at rest in such patients. The quantification of repolarization heterogeneity with ECG, QT dispersion, has some methodological limitations and has been abandoned in daily practice. Many studies have shown that body surface potential mapping (BSPM) contains more diagnostic and prognostic information than that elicited from a 12-lead ECG. The BSPM and magnetocardiogram (MCG) are two new developed recording methods, and provide higher spatial resolution than traditional ECG signals but with the disadvantages of high cost and huge volume. It is impossible to be used in a portable way. Previously, the investigators had utilized a 64-channel low-TC SQUID MCG device to develop and verify 2 parameters, so called smooth index of QTc (SIQTc) and T wave propagation (TWP), to accurately detect and localize the myocardial ischemia. Recently Nakai, et al. reported that a newly developed 187-ch signal-averaged vector-projected ECG (187-ch SAVP-ECG) could evaluate low-amplitude high-frequency potentials and repolarization heterogeneity. In this project, the investigators'll try to modify and improve the spatial resolution of ECG signals from a Self-built-in multichannel ECG system with a newly developed algorithm, and also try to derive the SIQTc and TWP from this system, for early detection of CVD. The investigators intend to prove the concept that this newly developed multichannel ECG system could efficiently detect or diagnose CVD with acceptable sensitivity and specificity, and in a portable way.