Anatomopathology of the normal and abnormal AV conduction system

Sudden fetal death due to dualism of the sino-atrial node

First, we report a sudden fetal death at 33(+3)weeks due to sino-atrial node dualism. The female stillborn was delivered by induced labor. The postmortem examination of the cardiac conduction system revealed a dualism of the sino-atrial node, associated with fragmentation of the atrio-ventricular node and His bundle. These abnormalities of the cardiac conduction system represent the morphological substrate for the development of malignant arrhythmias. In particular, the dualism of the sino-atrial node can cause the dissociation of the longitudinal nodal impulse into two distinct ways of different pulse generation, resulting in supraventricular tachyarrhythmias. This observation suggests new avenues of research on the pathogenesis of the sudden unexpected fetal death. Moreover, our findings confirm the need for an accurate postmortem examination, including serial sectioning of the cardiac conduction system, in every case of unexplained fetal death, following standardized autoptic protocols.

Antibodies to cardiac Purkinje cells: further characterization in autoimmune diseases and atrioventricular heart block

We confirmed the occurrence of IgG antibodies reacting with ox cardiac conducting tissue in the serum of some human subjects. These antibodies failed to react with all ox cardiac conducting tissue cells; they reacted only with the cells defined as Purkinje cells. Having checked 352 sera, we found that the prevalence of antibodies to Purkinje cells was 11% in normal subjects (no correlation with sex and age), 14% in systemic lupus erythematosus, 21% in rheumatoid arthritis, 18% in progressive systemic sclerosis, and 23% in Sjögren syndrome. In 50 patients with permanent pacemakers for chronic non-postinfarction atrioventricular (AV) block the prevalence was 30% (P = 0.008). In a selected set of 29 patients with clinically idiopathic AV block located at or below the level of the His bundle the prevalence was 34.5% (P = 0.006). The possible role of anti-Purkinje cell antibodies in autoimmune damage of cardiac conduction tissue is discussed.