Electrophysiological and histological correlations in two cases of complete heart block.

Electrophysiological and histological correlation was documented in 2 cases of complete heart block (CHB). Case 1 (77 yrs. female): CHB continued for 1.5 years with normal QRS in axis and duration. The His bundle electrogram (HBE) showed A-H block with normal H-V interval (40 msec). Ten months later she died of bronchopneumonia and paralytic ileus. Histological study of the conduction system revealed a giant nodule of calcification in the mitral ring and central fibrous body, which compressed the end of the A-V node and most part of the penetrating portion of the A-V bundle. Above-mentioned findings were thought to be compatible with A-H block in HBE. Case 2 (82 yrs. male): His EGG showed CHB with QRS configuration of right bundle branch block (RBBB) with left axis deviation (LAD), with transient appearance of RBBB with right axis deviation (RAD) or left bundle branch block (LBBB) patterns. The HBE revealed normal PH interval (120 msec), and the site of block was distal to the A-V bundle. In addition to the H potential, spike 'X' was also recorded 20 msec before QRS wave. He died suddenly after 1.5 years of hospitalization. Histological examination revealed that both anterior and posterior fascicles of the left bundle branch showed severe destruction at their origins, and the right bundle branch also showed marked fibrosis. These histological fi ndings were so-called ` 'trifascicular block' and compatible with H-V block in HBE. And the meaning of the 'X' spike in HBE was discussed.