Anatomical problems with identification and interruption of posterior septal Kent bundles.

To gain insight into the cause of the complex anatomical problems associated with posterior septal Kent bundles, 20 cadaver hearts were carefully examined and the operative results in 22 patients analyzed. The following important anatomical relationships were noted. The posterior right atrium overlies the left ventricle and muscular septum. The coronary sinus wall contains myocardium continuous with both atria. The posterior superior process of the left ventricle connects the mitral annulus to the muscular septum. The epicardium of the crux can be 2.5 to 3.5 cm from the right fibrous trigone. A Kent bundle can originate in either atrium, the atrial septum, or the coronary sinus and connect with the left ventricle or muscular septum. At operation, antegrade and retrograde activation sequences were used for identification. Antegrade maps could not be recorded in 4 patients. Two operations were used, right atrial and left atrial. The initial right atrial operation was successful in 12 patients--all 7 with earliest antegrade activation over the midpart of the muscular septum or its right side and 3 with activation on its left side. Among the 6 patients with more than one operative approach, 5 had Kent bundle division. One of the patients probably had a left free wall pathway. Two pathways thought to be free wall turned out to be septal. The Kent bundles were divided in 18 patients and missed in 4, 2 of the latter having His interruption. There were no deaths. The conclusions are that the right atrial operation is reliable when the pathways are clearly posterior septal. Surgical problems occur because Kent bundles in the posterior left free wall sometimes cannot be separated from Kent bundles in the posterior septal area. Both right atrial and left atrial operations are needed if there is doubt about the location of a pathway.