The clinical anatomy of the atrioventricular conduction axis

It is axiomatic that the chances of achieving accurate capture of the conduction axis and its fascicles will be optimized by equally accurate knowledge of the relationship of the components to the recognizable cardiac landmarks, and we find it surprising that acknowledged experts should continue to use drawings that fall short in terms of anatomical accuracy. The accuracy achieved by Sunao Tawara (1906) in showing the location of the atrioventricular conduction axis is little short of astounding. Our purpose in bringing this to current attention is to question the need of the experts to have produced such inaccurate representations, since the findings of Tawara have been extensively endorsed in very recent years. The recent studies do no more than point to the amazing accuracy of the initial account of Tawara. At the same time, we draw attention to the findings described in the middle of the 20th century by Ivan Mahaim (1947). These observations have tended to be ignored in recent accounts. They are, perhaps, of equal significance to those seeking specifically to pace the left fascicles of the branching atrioventricular bundle. Graphical Abstract The illustrations show, in the left hand panel, how the atrioventricular conduction axis can be separated into its atrial and ventricular parts at the point of insulation by the fibrous tissues of the atrioventricular junction, indicated by the double-headed black arrow. The middle panel shows our understanding, based on our previous investigations, of the location of the left bundle relative to the aortic root, while the right panel shows an example of the 'paraspecific' conduction system described by Ivan Mahaim.