[Effect of sparteine sulfate on the predamaged conduction system of the heart].

Antiarrhythmic drugs are known to cause AV-blockade. In animals and healthy humans the alcaloid of the gorse sparteine sulphate has been reported not to cause those side effects. We have studied in 10 patients with predamaged conduction system the grade of AV-blockade, the AV-interval and the intraventricular excitation spread by e.c.g. after i.v. injection of 200 mg sparteine sulphate (ajmalin, 50 mg i.v. as control). In 6 out of 10 patients no side effects have been observed. In 4 patients both sparteine and ajmalin injection caused higher graded AV-blockade. Our results suggest that sparteine sulphate like other antiarrhythmic drugs should not be administered to patients with a predamaged conduction system.