Effect of Diphenylhydantoin on Left Ventricular Function in Patients with Heart Disease

The effect of 250 mg of diphenylhydantoin, administered intravenously, on left ventricular function was determined during cardiac catheterization in nine patients with heart disease.Five minutes after drug administration, left ventricular end-diastolic pressure rose in each patient from an average of 6.0 mm Hg to 10.0 mm Hg. Concurrently, stroke work and stroke power indices decreased in each patient by an average of 22.0% and 22.2%, respectively. Stroke volume index decreased in seven patients and maximum left ventricular dp/dt fell in eight patients. Over the next 25 minutes, all parameters returned to control values. Cardiac index was unchanged, whereas generally small and insignificant changes were observed in heart rate and systemic arterial pressure throughout the study.Although this study has demonstrated that diphenylhydantoin depresses myocardial function, the effect may have limited clinical significance since it was relatively short-lived and did not reduce cardiac output or greatly elevate ventricular end-diastolic pressure. Furthermore, the absence of a significant systemic hypotensive effect is of distinct clinical importance.