[Electrophysiologic effects of propafenone in patients with sinus node dysfunction].

The electrophysiologic effects of intravenously administered Propafenon (1,5 mg/kg) were evaluated in 16 patients (mean age: 62,1 +/- 11 years) with sinus node dysfunction, shown by sinus bradycardia or intermittent sino-atrial block. The variations of sinus cycle length were not statistically significant (NS), (1137,1 +/- 244,9 msec versus 1191,9 +/- 321,1 msec). In one patient sinus rate markedly decreased from 36 to 28 beats/min. In 2 patients the cycle length of a junctional rhythm was comparable before and after drug administration; in both patients the rate of the junctional rhythm decreased and in one markedly (from 39 to 32 beats/min). Sinoatrial conduction time increased in 4 patients and decreased in 6. The variations were not statistically significant (223,8 +/- 76 msec versus 230,6 +/- 75,9 msec). In one patient the sinoatrial conduction time which was normal during the control study, could not be evaluated after Propafenon due to the appearance of a retrograde block between the atrium and the sinus node. Maximum corrected sinus node recovery time was prolonged by the drug in 9 patients and shortened in 5. In 2 patients the sinus node recovery time was prolonged to about 10 sec. The mean value of corrected sinus node recovery time increased from 883,6 +/- 995,8 msec to 1820,5 +/- 2894 msec (NS). Propafenon significantly prolonged the effective refractory period and the functional refractory period of the atrium, as well as the A-H, H-V and QRS intervals, the A-V node functional refractory period, the relative refractory period of His-Purkinje system and the ventricular effective refractory period.(ABSTRACT TRUNCATED AT 250 WORDS)