[Electrocardiology basis of paroxysmal atrial fibrillation (author's transl)].

55 patients (15 subjects in whom a special cardiac disease could be ruled out and 40 patients with paroxysmal atrial fibrillation) were investigated by means of the extrastimulus method at a driving rate of 80 min-1. In 32 of the 40 patients with paroxysmal atrial fibrillation occurred signs of atrial vulnerability. When compared with the healthy subjects and the remaining 8 patients who did not fulfil the criteria for vulnerability, there were significant shorter effective and longer relative refractory periods of the right atrium in the vulnerability group. These findings suggest that the re-entry phenomenon may be the underlying mechanism of paroxysmal atrial fibrillation in the group with atrial vulnerability.