Hypertrophic cardiomyopathy and transposition of great arteries associated with maternal diabetes and presumed gestational diabetes

Maternal diabetes mellitus affects the foetal heart both structurally and functionally. In early gestation, it has a teratogenic effect causing defects of primary cardiogenesis. In late gestation, it causes a unique form of hypertrophic cardiomyopathy. We report an infant of a diabetic mother and an infant where there was presumed gestational diabetes during the pregnancy who presented with combined severe hypertrophic cardiomyopathy and complex transposition of the great arteries. This rare combination of structural and functional cardiac abnormalities reflects the different mechanisms and timings of injury that may occur to the foetal heart in association with maternal diabetes and has not been previously reported. The combination has significant implications regarding medical and surgical management, and necessitates prolonged supportive therapy whilst awaiting regression of the hypertrophic cardiomyopathy followed by delayed arterial switch operation.