Part of the autonomous nervous system in the development of chaotic post-extrasystolic pictures. Electrophysiological and pharmacological studies of 49 cases.

The interpretation of post-extrasystolic parameters and their significance is discussed. Programmed extrastimulation according to Strauss was carried out in 49 cases, before and after atropine and propranolol administration. The result was a computable sinoauricular conduction time (SACT), a chaotic picture, or an ascending line without plateau. The patients were selected on basis of their intrinsic heart rates (IHR). If the total SACT exceeded 250 ms, the chaotic post-extrasystolic picture and the ascending 1st phase without plateau were considered pathologic, then after drug testing the ratio of pathologic parameters decreased from 54 to 22% in cases with normal IHR. Including cases with pathologic IHR the ratio increased from 55 to 90%, especially in asynchronous chaotic pictures. After drug testing the chaotic forms were always replaced by a plateau in cases with normal IHR, but in pathologic ones the chaotic picture appeared to be a dominant electrophysiological parameter. It follows that the autonomous nervous system has its part in the development of chaotic post-extrasystolic pictures. A plateau in the post-extrasystolic curve could mean a functional organization and synchronism rather than a conduction disturbance; to the latter a high-level plateau would correspond.