Complete heart block as a consequence of atrionodal discontinuity

We have recently studied a case of complete heart block in which there was considerable difficulty in deciding whether it was of congenital or acquired origin. This was because the heart block wasfirst discovered at the age of 2 years in the course of acute diphtheria. Though diphtheritic infections are known to affect the cardiac conduction system, authenticated cases of post-diphtheritic block persisting after the infection are rare, and, furthermore, histopathological study in this case revealed discontinuity between the atrial tissues and the more peripheral parts of the atrioventricular conduction tissues. This has been more commonly observed in congenital cases of complete heart block and it has been postulated on theoretical grounds that this could be the basis for congenital heart block; on the other hand, it has been noted in a single case thought to be of acquired origin. Review of the evidence availablefailed to allow accurate classification of the case into either congenital