Lesions in the Auriculoventricular Conduction System Occurring in Rheumatic Fever.

In spite of the fact that disturbances in conduction and rhythm in the heart form an almost invariable and conspicuous finding in active rheumatic fever, remarkably few histological studies have been reported on the tissue of the conduction system in this disease. Thus, for example, the microscopic findings in this tissue from cases of conduction disturbances in rheumatic fever are reported only in single instances each in the excellent monographs of Monckeberg' and Mahaim.2 In addition to these two authors, scattered reports on very limited material have been made by Gerhardt,3 Bramwell,4 L6w,3 and Naish and Kennedy.6 The reported findings refer to infiltrations of the bundle with inflammatory cells (in one instance with giant cells), swelling of collagen, "fibrous degeneration of the auriculo-ventricular bundle of His with the presence of a calcareous nodule almost obliterating the bundle," and, more significantly, "lymphocytic infiltration in the region of the node and trunks." Because of the very limited nature of these reports it is not surprising that various explanations of the cause of the conduction disturbances have been advanced, such as myocardial fatigue, toxic injury, the presence of specific lesions and accumulation of fluid in the synovial sac which was assumed to surround the conduction system in man. Published reports by one of us (L. G.) with collaborators 7-12 have indicated a high incidence of inflammatory and vascular changes occurring in vanous parts of the heart in rheuimatic fever. It seemed of interest, therefore, to study systematically the conduction system in a representatively large series of cases of unquestionable rheumatic nature in which other affections which might implicate this tissue could be reasonably ruled out.