Hemorrhage in cardiac conduction tissue in premature infants.

Six premature infants had hemorrhages that were limited to cardiac conduction tissues. Obstetric complications occurred in each; four were growth retarded, and four had perinatal asphyxia. Two babies survived beyond one week. Four survived less than 24 hours. Bradyrhythmias occurred in four. Extracardiac lesions included infections and renal failure in two infants, hyaline membrane disease in one, hypoplastic lungs in two (one with renal agenesis and placental amnion nodosum), and placental villous edema in two. Cardiac hemorrhage occurred in sinoatrial nodes (n = 1), atrioventricular nodes (n = 3), atrioventricular bundles (n = 3), left bundle branches (n = 5), and right bundle branches (n = 3). The lesions were macroscopic in five cases. These cases suggest that neonatal cardiac conduction tissues are vulnerable to hemorrhage, particularly if associated with perinatal insults. Such lesions may account for some idiopathic dysrhythmias in surviving babies.