Amplitude alterations between sinus rhythm and ventricular tachycardia or ventricular fibrillation in surface and intracardiac leads in human subjects

This study was performed to quantify the electrocardiographic amplitude alterations that occur in the transition from sinus rhythm (SR) to ventricular tachycardia (VT) or ventricular fibrillation (VF) in human subjects. Measurements were made of QRS complexes on surface ECGs and of intraventricular depolarizations. Patients were studied in three categories: Group A (no drugs), Group B (Amiodarone), and Group C (Procainamide). In ventricular tachycardia the authors found increases in every lead in all three groups. Lead I increases ranged from 12-52%; in Lead III increases were 49-148%; in Lead VI Increases were 20-54%. Ventricular tachycardia measured from the right ventricular apex (RVA) showed increases ranging from 24-49%. In ventricular fibrillation, amplitudes exhibited both increases and decreases in Leads I and VI, and increases in Lead III. In the RVA, ventricular fibrillation amplitude decreased in all three groups, ranging from -2-55%. Results of VF for Amiodarone and Procainamide are inconclusive doe to the small patient sample size. The data show that there is a significant increase in VT amplitude over SR, as well as a relationship in VT amplitudes between drug and no drug groups in every lead Also, VF was characterized by decreased amplitudes or markedly smaller increases than VT