[Electrophysiologic effects of the calcium antagonist isradipine, a double-blind placebo controlled study].

: The electrophysiologic effects of the calcium channel antagonist isradipine (0.5 mg) in comparison to placebo were evaluated in a double blind study with nine patients in two groups. The patient groups were not different in respect to the underlying cardiac disease, electrophysiologic parameters at the baseline study, or in blood pressure. Isradipine significantly decreased the systolic (p less than 0.01) and diastolic (p less than 0.05) blood pressure, while sinus cycle length decreased significantly (p less than 0.05) in the placebo group and the isradipine group with no difference between the two study groups. The influence on sinus node recovery time, effective refractory period of the av-node, intranodal conduction time, and PR interval were not significant. In conclusion, isradipine significantly decreased systolic and diastolic blood pressure. The decrease in sinus cycle length after intravenous isradipine was not significantly different from the decrease seen in the placebo group. Atrioventricular conduction was not significantly affected.