Electrophysiologic and antiarrhythmic effects of nitroglycerin in man.

The electrophysiologic properties and the arrhythmic disposition of the human heart were determined in 16 patients before and after the intravenous administration of nitroglycerin (0.25 and 0.50 micrograms/kg/min). At the higher dose, nitroglycerin significantly shortened the atrial and ventricular effective refractory periods and bundle of His-Purkinje conduction (HV interval). Otherwise, a paucity of general electrophysiologic effects was noted; atrial conduction intervals were not altered, and although a trend toward shortening occurred, the sinus node function studies (conduction and recovery times) and atrioventricular nodal conduction did not change significantly with nitroglycerin. Nitroglycerin demonstrated antiarrhythmic properties; the ventricular echo zone and the number of ventricular echo-repetitive ventricular response beats following ventricular stimulation decreased significantly with nitroglycerin. Nitroglycerin ameliorated the tendency toward sustained repetitive ventricular response in 4 of 5 patients and obliterated the development of this tachyarrhythmia in 1. Although the precise mechanisms were not delineated by this study, it is clear, that nitroglycerin causes some change in the electrophysiologic properties of the human heart and that it appears to have (or elicit) beneficial antiarrhythmic effects.