Conduction system in two cases of sudden death two years after the Mustard procedure.

This report describes a serial section examination of the conduction system in two children who died suddenly 2 years following the Mustard procedure for complete transposition. The first child manifested sinus rhythm alternating with junctional rhythm in the last year of life. The second child, 2 months before death, had first-degree atrioventricular (AV) block which progressed to second-degree block with 2:1 conduction alternating with a junctional rhythm with AV dissociation. Examination of the conduction system in both cases revealed the approaches to the sinoatrial (SA) and the AV nodes to be markedly fibrosed. In addition, in Case 1 the SA node was interrupted by sutures and in Case 2 the SA node was considerably fibrosed. The arrhythmias produced and the probable cause of sudden death in both cases may be related to surgical injury to the approaches to the SA and AV nodes. This study and the review of the literature emphasize the necessity of maintaining the integrity of the SA node, the approaches to the SA and AV nodes, and the superior preferential pathway while performing the Mustard procedure for complete transposition.