Abstract
A report of modulated ventricular parasystole is described in a patient presenting with acute myocardial infarction and classical (nonmodulated) ventricular parasystole. After infusion of intravenous lidocaine, the pattern of QRS distribution changed to one of modulated parasystole. This observation suggests that lidocaine altered the receptivity to electrotonic depolarizations and changed the slope of phase 4 depolarization.