Heart failure in the neonate due to extreme abnormalities of heart rate: clinical and radiographic features.

Extreme variations of heart rate caused clinical and radiographic findings of heart failure in six neonates in the absence of structural heart disease. Two infants had heart block with heart rates below 50/min and four had paroxysmal atrial tachycardia with rates approaching 300/min. Each infant had interstitial or alveolar pulmonary edema and most had cardiomegaly. After restoration of a normal heart rate, there was rapid and dramatic resolution of pulmonary edema and reduction in cardiac size.