[Use of ajmaline in the diagnosis of sick sinus syndrome with a-v associated conduction defects].

The electrophysiological effects of ajmaline (1 mg/Kg i.v.) on sinus node were evaluated in 63 control subjects and in 12 pts with sick sinus syndrome (S.S.S.). In the control group the mean spontaneous cycle length (S.C.L.) was found significatively (less less than 0.001) reduced (8,?%), and corrected sinus node recovery time (C.S.N.R.T.) significatively (p less than 0.01) prolonged (30,2%) by the drug. In the patients with S.S.S. the S.C.L. was prolonged by 16% but not significatively and the C.S.N.R.T. by 60,7% (p less than 0.05). In 8/12 pts, with S.S.S. spontaneous sinoatrial blocks appeared or were more frequently observed following ajmaline injection. The use of ajmaline as a unic pharmacologic test for the differential diagnosis of symptomatic bradycardia in patients with atrioventricular associated conduction defects is discussed.