[The effect of diphenylhydantoin on the automatism of the sinus node and on the sino-atrial conduction time in patients with and without sick sinus syndrome].

In 30 test persons (15 patients with disturbed function of the sino-auricular node, 9 of them with classical sick-sinus-syndrome as well as 15 test persons without disturbance of the sino-auricular node, of them 7 healthy ones) the influence of diphenylhydantoin on the function of the sino-auricular node was tested. By means of atrial stimulation the so-called sino-atrial conduction time, the recreation time of the sino-auricular node as well as the duration of the sinus period before and after intravenous application of 250 mg of diphenylhydantoin was estimated. The auricular stimulation was carried out either through an oesophageal electrode probe or usually through an electrode catheter directly placed in the right atrium. In the entire collective the sino-atrial conduction time did prolong itself statistically not significantly by 2 +/- 5ms (x +/- 2 s), in which cases there was not to be observed a different behaviour between test persons with a healthy rhythm and patients with disturbed function of the sino-auricular node. In 2 patients with sick-sinus-syndrome, however, after diphenylhydantoin and individual atrial stimulation in each case sino-atrial blockings of higher degree developed. The maximum absolute and corrected recovery time of the sino-auricular node prolonged itself in patients with syndrome of the sino-auricular node by on an average 1406 +/- 2120 ms or 1378 +/- 2338 ms, in which cases in 1 test person a threatening prolongation of the poststimulation pause to 10 s developed. In another patient after application of diphenylhydantoin an atrial arrest was observed. The automatism of the sino-auricular node of test persons with healthy rhythm was not influenced.