Congestive Heart Failure Due to Left-to-Right Shunts

Among 87 infants and children with congestive heart failure due to L-R shunts, 67 (77.1%) developed symptoms and signs of heart failure during infancy. The mode of onset was characteristically insidious, and varied with different types of L-R shunts. Symptoms and signs commonly observed were tachycardia, tachypnea, prolongation of the time needed for feeding, hepatomegaly, cardio-megaly and roentgenological evidences of pulmonary congestion. The hepatomegaly, a sign of right ventricular failure was almost invariably noted in infants with failure, even in those of PDA, who, as traditionally believed, pertained to the left ventricular decompensation. Large pulmonary blood flow and high pulmonary arterial pressure were the altered hemodynamics most commonly encountered. The pulmonary blood volume was usually increased, which could be limited or even compromized by the mechanisms, such as pulmonary vasocon-striction or vascular obstructive disease, and shortening of the mean pulmonary transit time. Augmentation of the pulmonary blood flow alone seemed to be not causing significant respiratory distress, such as tachypnea unless left ventricular failure supervened. Five important factors were pointed out in our present studies as contributing to the development of heart failure due to L-R shunts: 1) Abnormally rapid decrease of the pulmonary vascular resistance following birth. 2) Large size of the defect. 3) Level of the systemic-pulmonary communication. 4) Presence of associated cardiac anomalies. 5) In-fection.