Abstract
A morphological study of hemiblock affecting the left bundle branch was performed by three-dimensional imaging to obtain a clear description of the pathological changes in both branches. The preparations were autopsied hearts of 27 patients shown electrocardiographically to have suffered from bifascicular block (20 men and 7 women, ranging from 64 to 88 years) . The controls were six autopsied electrocardiographically normal hearts. Serial sections of 70μm, were prepared from the autopsied hearts by the method of Lev. The samples were imaged at 420μm intervals, by a personal computer and a digitizer. The remaining conduction cells were color-sorted at 4 levels. In the left bundle branch, a residual area of less than 25% was treated as significantly losing area. Left bundle branch disturbances varied, ranging from those limited to the origin to extentive lesions affecting the peripheral portion. Lesions affecting the His bundle were noted in some. Loss patterns of conduction systems in three-dimensional images were divided into three groups : localized, scattered, and extensive types. Of the 27 cases observed, finding of 21 corresponded to the electrocardiographic data. By additional factors of location, three-dimensional images were grouped into 6 subgroups. Scattered type lesions throughout the conduction system were characteristic of chronic myocarditis. It is suggested that damage of chronic myocarditis increased by scattering from localized injury, and then fused into single extensive lesions.
