Surgical anatomy of accessory connections of atrioventricular conduction

Forty-nine descriptions of accessory pathways of atrioventricular (AV) conduction have been analyzed in the search for reasons for an occasional failure of interruption by operation. The validity of the steps now used for open interruption of connections was confirmed. Several possible but highly speculative reasons were found for failure. A pathway might remain intact after operation because atrial muscle on the AV valve may act as a pathway route after an atriotomy made just above the annulus. In another situation, the AV valve myocardium might be continuous with a papillary muscle directly attached to the valve. The small, middle, and great coronary veins, when budding from the coronary sinus, might carry with them an AV connection that escaped the invasion of the primitive AV junction by sulcus tissue. Final proof of these conjectures awaits more studies of hearts with accessory pathways of AV conduction.