Pathology of coronary narrowing after arterial switch operation: autopsy findings in two patients who died within 3 months of surgical treatment and review of the literature.

The arterial switch operation (ASO) has become the surgical treatment of choice for transposition of the great arteries (TGA). Myocardial ischemia owing to coronary complication remains the commonest cause of mortality and morbidity following ASO. The main clinical manifestations of coronary obstruction reported after a switch procedure are heart failure, arrhythmias, or sudden death. Coronary complications are responsible for about 50% of early death and for almost all late deaths. We describe pathologic and anatomic findings in two cases of late sudden death after an ASO. Critical intimal thickening and acute take-off of coronary trunks were the main pathological substrates of death. Histological examination revealed an obstructive coronary proliferation characterised by a concentric stratum of intimal smooth muscle cell hyperplasia with preserved tunica media. Pathogenetic assessment of intimal coronary lesions after an ASO should consider the role of endothelium and vascular parietal wall in the unavoidable response to injury caused by arterial reconstruction. Since a rapidly progressive proliferative disease is suspected, to explain coronary narrowing, understanding endothelial biology and improving surgical technique should help to prevent late coronary events.