Ischemic myocardial necrosis and papillary muscle dysfunction in infants and children.

Ischemic myocardial and papillary muscle dysfunction has considerable implication in newborn infants and children with normal or malformed hearts. Papillary muscle dysfunction in adults primarily involves coronary artery occlusion and ischemic necrosis in the left ventricle and papillary muscles. Infants and children rarely develop coronary artery occlusion. Their myocardial dysfunction and injury occurs with nearly equal frequency in both ventricles as a result of underperfusion from a wide range of causes, including severe birth asphyxia, congenital heart disease, and complications of premature delivery. A history of cardiogenic shock, acute congestive heart failure with cyanosis and atrioventricular murmur, or persistent fetal circulation in a newborn without congenital heart disease should alert the pathologist to the possibility of ischemic myocardial necrosis (IMN). Older infants with ventricular hypertrophy, persistent pulmonary hypertension (PPHN), bronchopulmonary dysplasia (BPD), and those with malformed hearts involving severe ventricular hypertension due to outflow obstruction or pulmonary hypertension may have IMN, fibrosis, or dystrophic calcification alone or in combination. Animal models of adult ischemic cardiac injury may not be suitable for study of the newborn.