HIS BUNDLE ELECTROGRAM IN RHEUMATIC MITRAL VALVE DISEASE WITH SPECIAL REFERENCE TO BACHMANN'S BUNDLE BLOCK IN P MITRALE

Abstract

HBEs were recorded from either the right or left ventricle or simultaneously from both in 26 patients with chronic rheumatic mitral stenosis alone or in association with other mild valvular lesions during th diagnostic cardiac catheterization. Eleven of the patients had auricular fibrillation. Of the remaining 15 patients with sinus mechanism and P mitrale in the surface electrocardiogram, 12 were noted to have H potential preceded the termination of P wave and gave P₂H interval of negative value -so-called "Bachmann's bundle block". Among these, double atrial activities (A and A' waves) could be identified on the HBE recorded from the left ventricular endocardial surface with catheter electrodes positioned at the subaortic region in 7 patients studied. Interatrial conduction time (P₁A' interval) measured in these patients was prolonged in all and ranged from 47 to 82 with an average of 66 msec. Prolongation of intraatrial (or internodal) conduction time was noted in only one patient who also had first degree A-V block and prolonged A-H interval. There was no cor-relation of either P₁P₂ or P₂H interval to the degree of left atrial enlargement. The P₁P₂ or P₂H interval also had no correlation with hemodynamic parameters. In patients with auricular fibrillation, all impulses unable to conduct to the ventricle were blocked proximal to the His bundle and concealed conduction was not observed distal to it.