Abstract
The electrophysiological effects of intravenous propranolol (0.15mg/kg) were studied in 26 patients with sinus node dysfunction (SND group) and 9 patients with normal sinus node function (control group). Spontaneous cycle length and AH interval were significantly increased in the control and SND groups after propranolol. PA and HV intervals, calculated sinoatrial conduction time and refractory periods of the atrium, AV node and ventricle were not significantly changed in either group. Maximum corrected sinus node recovery time (max CSRT) was not changed in the control group, but it was significantly prolonged in the SND group. These results of the overdrive suppression test were in disagreement with those of previous studies. Propranolol lengthened spontaneous cycle length (by more than 200 msec) and/or max CSRT (by more than 1000 msec) in 8 of 26 patients with SND. Thus, it is suggested that propranolol should be used with caution in patients with SND.
