Late dysrhythmias and disturbances of conduction following Mustard operation for complete transposition of the great arteries.

Between 1964 and 1971, 49 patients were discharged from hospital following atrial baffle repair for transposition of the great arteries. Electrocardiograms of 47 of these patients were available for review seven months to eight and a half years (average 31 months) after operation. Of the 46 patients in sinus rhythm prior to operation, 40 (87%) were in sinus rhythm with normal atrioventricular conduction when last seen. Four patients (8.7%) had benign supraventricular dysrhythmias: three were junctional, one was atrial. None was noted to experience rapid dysrhythmias. Two patients showed evidence of abnormal atrioventricular conduction. There were five late deaths but in only one of these patients was a dysrhythmia a possible factor. The effects of variations in caval cannulation, extent of excision of the atrial septum and placement of the baffle suture line on the rhythm present at last review were examined. To preserve sinus rhythm it appears necessary to avoid surgical trauma in the vicinity of both the sinus node and the A-V node. Preservation of the internodal tracts appears less important. It is uncertain whether the 'sinus' rhythm seen after operation originates in the sinoatrial node but the rhythm is functionally similar.