Right ventricular infarction: unusual electrocardiographic and electrophysiological manifestations.

Right ventricular infarction occurs in 19-43% of patients with acute inferior wall infarction (Lorell et al., 1979). Its clinical, hemodynamic, and anatomic features are well known and include associated inferior wall infarction, distended neck veins, clear lung fields, hypotension, and heart block (Cintron et al., 1981; Coma-Canella et al., 1979; Lloyd et al., 1981; Lopez-Sendon et al., 1981; Raabe and Chester, 1978; Rotman et al., 1974). Isolated right ventricular infarction is less frequent and occurs in 2.5-4.6% of autopsy studies of myocardial infarction (Cohn et al., 1974; Erhardt et al., 1976; Wartman and Hellerstein, 1948). This report describes a patient with isolated right ventricular infarction with unusual electrophysiological findings. Her initial electrocardiogram showed atrial escape rhythm with incomplete right bundle-branch block and left posterior hemiblock. Later, she developed atrioventricular (AV) block with supra- and infra-Hisian, "phase 4," conduction defects. The sinus malfunction and high degree AV block persisted over 2 weeks and an atrioventricular sequential pacemaker was implanted. Hymodynamic study showed that her cardiac output was highly dependent on the heart rate and properly timed AV interval, and the pacemaker was programmed accordingly.