RELATION OF VENTRICULAR REPOLARIZATION TO ELECTROCARDIOGRAPHIC T-WAVEFORM AND ARRHYTHMIA VULNERABILITY

The normal sequence of ventricular recovery proceeds from epicardium to endocardium, but on the epicardium the pattern of ventricular recovery is similar to the pattern of activation. Ventricular repolarization data were obtained from analyses of ECG, suction potential recordings, recordings of transmembrane action potentials, and from measurements of refractory periods. Normal ventricular repolarization is characterized in sufficient detail that it can be used with theoretic models to derive T waves with forms corresponding closely to recorded T waves. These models aid in explaining body surface manifestations of electrophysiologic events of ventricular repolarization and contribute to a physiologic approach to interpreting T wave abnormalities in clinical ECG. A relationship between inhomogeneity of ventricular refractory period duration and arrhythmia vulnerability was documented. Because inhomogeneity of ventricular repolarization is a factor in T wave-form and arrhythmia vulnerability, analytical methods of the T wave for determining patients at risk of developing arrhythmias should be possible. One such analysis is presented. The method was tested on experimental animals before and after interventions designed to increase arrhythmia vulnerability and in a limited number of patient studies. The results are satisfactory and suggest that in the future ECG examination will be used as a prognostic tool in addition to its diagnostic function.