Sudden infant death syndrome (SIDS): cardiac pathologic observations in infants with SIDS.

To determine the relation between the sudden infant death syndrome (SIDS) and asymmetric septal hypertrophy (ASH), pathologic obervations weree made in 45 infants who died with SIDS. Ventricular septal to left ventricular free wall ratios were normal (less than 1.3) in 42 infants and increased in three others (ratios of 1.4, 1.4, and 1.6). However, in none of these three infants with abnormal septal-free wall ratios was the ventricular septum markedly thickened. Small foci of disorganized cardiac muscle cells, similar to those observed in patients with ASH (but less marked in severity), were present in the ventricular septum of 22 per cent of controls. Thus, we have found little pathologic evidence to suggest that SIDS and ASH are commonly associated, although a rare coexistence of these two conditions is possible.