[The effects of tolamolol on excito-conduction in men (author's transl)].

The electrophysiologic effects of tolamolol (UK-6558-01), a new beta-adrenergic blocking agent, were studied using the endocavitarian electrocardiography and the extrastimulus method. The drug was infused intravenously in the dose of 20 mg (0,23-0,36 mg per kilogram). Tolamolol resulted in: -- prolongation of sinus cycle length in 17 patients (P less than 0.001); -- prolongation of correct sinus node recovery time in 16 patients (P less than 0.001); -- there was no significant modification in intra-atrial conduction (P less than 0.3), while atrail effective refractory period was slightly lengthened (P less than 0.03); -- in A-V node conduction was prolonged in 17 patients (P less than 0.001) and the effective functional refractory periods were prolonged in all patients (P less than 0.001); -- a A-V block of 2 degrees grade appears in 17 patients at a more prolonged cycle length (P less than 0.001). Tolamolol had no effect on His-Purkinje system conduction time as well as the relative refractory period, measured before and after the drug in 2 patients. In 6 patients, during the induction of extrastimuli an "echo zone" appeared; after tolamolol its duration was reduced in 4 patients, in one unchanged and in one abolished. The therapeutical properties of this drug are discussed on the basis of such experimental data.