Comparative electrophysiological evaluation of atrial activation and sinoatrial node function following Senning and Mustard procedures: an experimental study.

We compared several electrophysiological variables before and after Mustard and Senning procedures in 14 mongrel dogs and made the following three observations. First, after the Senning operation, the atrial activation in the areas of the anterior and middle internodal tracts is undamaged. After the Mustard procedure, however, conduction through the interatrial septum is practically abolished. Both techniques damage the area of the posterior internodal tract. On the whole, there is greater dispersion of atrial epicardial mapping with the Senning operation. Second, several degrees of depression in the sinus node automatism and intraatrial conduction were observed with both techniques. Third, atrioventricular block in various degrees was observed only after the Mustard procedure. The atrioventricular dissociation observed after the Senning operation was dependent on sinus pacemaker dysfunction only. We think that from the electrophysiological point of view, the Senning procedure is a valid alternative for repair of transposition of the great arteries.