[Vectorcardiographic analysis of late potentials]

We analyzed by high amplification vectorcardiography the morphology of the QRS ending loop and the ST segment of patients with previously recorded Lown 4A, 4B ventricular arrhythmias and the healthy subject. Eight patients were affected by ischemic heart disease and 7 by arrhythmogenic right ventricular dysplasia. All had some irregularities at the end of the QRS or in the ST segment, on the standard ECG. The VCG showed one or more of these three morphologies: complete or incomplete ring, rapidly inscripted isodi-triphasic potentials, sinusoidal irregularities. In the 20 healthy subjects, the loop corresponding to the last 30 msec of the QRS, till the end of the afferent portion of T, was regular, without any particular morphology. We think that these aspects could be related to delayed fragmentation of the ventricular depolarization.