Effect of Nisoldipine on Electrophysiological Parameters in Man

Summary

The effect of nisoldipine on electrophysiological parameters was investigated in 20 patients. Ten of them were pretreated with a beta blocker ( atenolol 75 mg/day in nine patients, pindolol 15 mg/day in one patient) for at least 3 days prior to the electrophysiological study. Three catheters were advanced from the right femoral vein into the right heart. A No. 6F quadripolar catheter was placed in the high right atrium for pacing and sensing. The potentials of the His bundle were recorded with a No. 4F catheter. Another bipolar catheter was positioned in the apex of the right ventricle. Before and after the intravenous administration of 1.5 μg nisoldipine/kg body weight the following electrophysiological parameters were measured at sinus rhythm or atrial stimulation of 100 beats/min: spontaneous sinus node cycle length (A-A), sinus node recovery time (SNRT), rate-corrected sinus node recovery time (CSNRT), calculated sinoatrial conduction time (SACT), conduction times from high to low right atrium (HRA-A), from low right atrium to the His bundle (A-H), from the His bundle to the septum (H-V) and from the septum to the apex of the right ventricle (V-RVA). The effective refractory periods of the atrium (EPRA), the AV node (ERPAVN), the right ventricle (ERPV) and the functional refractory period of the AV node (FRPAVN) were determined with the extrastimuli technique at a paced cycle length of 600 ms. Blood pressure was measured with the cuff method.

In both groups nisoldipine induced a higher heart rate. Conduction times and refractory periods did not alter significantly. The effect of nisoldipine was further investigated in three patients with intermittent AV block II-III. In two of them nisoldipine did not alter conduction times. However, in one patient A-H time was prolonged from 290 to 410 ms. Baseline values were observed 10 min later.

It is concluded that nisoldipine does not exert major electrophysiological effects in patients without disturbances of the sinus and AV node. In patients with AV-block I, a transient increase of the A-H time may result after intravenous administration of nisoldipine.