[Cardiac electrophysiologic effect of various catecholamines and parasympatholytic agents]

Using His-bundle-electrography and programmed atrial stimulation the effects of different catecholamines (dopamine, dobutamine, orciprenaline), parasympatholytics like atropine, ipratropiumbromide and the xanthine derivative aminophylline have been studied on the conduction system of the human heart in 119 patients with and without different disturbances of rhythm. In contrast to dopamine a moderate effect was found by dobutamine (3 or 6 micrograms/kg/min) in patients with sinus node dysfunction and delayed AV-conduction. In comparison it must by pointed out, that orciprenaline has the greatest positive dromotropic and chronotropic effect on sinus and AV-node. No effect was seen by these catecholamines on electrophysiological properties of the atrium and the intraventricular conduction (HPS). Particularly the fatigue-phenomenon of the Tawara-fibers were not influenced. 0,24 g aminophylline has only a minimal electrophysiological effect, only the sino-atrial conduction time was shortened significantly. The parasympathomimetic agents atropine (1,0; 2 mg i.v.) and ipratropiumbromide (0,5; 1 mg i.v.) are able to improve the sinuatrial and AV-dysfunction. In some patients, however, paradoxical effects were seen in patients with sick sinus syndrome. The refractory periods of the HPS were not influenced - otherwise a secondary impulse - generator was accelerated, which seems to indicate that the AV-node is localized in the NH-region.