[His electrogram recordings in disturbances of atrio-ventricular conduction in acute ryocardial infarction (author's...

48 His bundle recordings were performed on 30 patients with acute mycardial infarction and various degrees of atrioventricular block. Studies were undertaken at the time of transvenous pacemaker insertion and/or removal from the right ventricle, without pharmacological or electrical stimulation tests. The connections between site of the infarcted area and localization of the a-v block were investigated, to identify uncommon relations. Several atypical cases were observed: among 12 cases of patients with anterior infarction, 6 had prolonged P-H interval, with prolonged H-V interval in 4 cases, and normal H-V interval in the remaining 2 cases. Among the 18 cases of inferior infarction, 5 had prolonged H-V interval, 2 of which had a normal P-H interval and 3 with prolonged P-H interval. In the latter cases, the identification of a two-step a-v block by His bundle recordings was shown to be important from the clinical and prognostic viewpoint. Nevertheless, it is evident that the His bundle recording is insufficient by itself to provide any evidence of the inner pathogenetical mechanism of these phenomena, and only various hypotheses can be advanced.