Relation of ventricular repolarization to electrocardiographic T wave-form 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. Data concerning ventricular repolarization have been obtained from analyses of electrocardiographic recordings, suction potential recordings, a limited number of recordings of transmembrane action potentials, and from measurements of refractory periods. Normal ventricular repolarization has now been characterized in sufficient detail that it can be used with theoretic models to derive T waves with forms that correspond closely to recorded T waves. These models provide insights concerning the body surface manifestations of the electrophysiologic events of ventricular repolarization and should contribute to a more physiologic approach to interpreting T wave abnormalities in clinical electrocardiograms. A relationship between inhomogeneity of ventricular refractory period duration and arrhythmia vulnerability has also been documented. Because inhomogeneity of ventricular repolarization is a factor in both T wave-form and arrhythmia vulnerability, methods of analysis of the T wave for determining patients at risk of developing arrhythmias should be possible. One such analysis is presented. The method has been tested on experimental animals before and after interventions designed to increase arrhythmia vulnerability and in a limited number of patient studies. The results to date are encouraging and suggest that in the future electrocardiographic examination will be used as a prognostic tool in addition to its already established diagnostic function.