Analysis of the T wave of the magnetocardiogram in patients with essential hypertension by means of isomagnetic and vector arrow maps.

Magnetocardiograms (MCGs) of 50 normal subjects and 40 patients with essential hypertension were recorded to determine the value of the MCG for detecting abnormal repolarization. Among the patients with essential hypertension, there were nine cases (22.5%) in whom isopotential maps did not show rightward repolarization vectors but isomagnetic and vector arrow maps showed a rightward repolarization vector in some areas in addition to the normal repolarization vector. Departure maps of the ECG showed an increased repolarization vector directed anteriorly in some of these cases. The repolarization abnormality was recognized in only the MCG departure map in four cases, while no case showed abnormality in only the ECG departure map. With the progress of hypertension, the repolarization abnormality was seen more frequently and its detection using the MCG was higher than that using the ECG. Furthermore, multiple dipoles were detected more frequently from the MCG than from the ECG. Thus the MCG seems more useful than the ECG in the analysis of repolarization abnormalities in essential hypertension.