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ExtractThe cardiovascular effects of propranolol (Inderal) [24] were compared in 13 adult dogs and 14 puppies. Left ventricular (LV) pressure was measured with a catheter tip manometer and myocardial contractility was assessed by LV measurements of peak rate of pressure development (LV dp/dt), LV dp/dt at 40 mm Hg LV pressure (P 40 dp/dt), and peak LV (dp/dt)/P. Cardiac output was measured by indocyanine green dye dilution. Measurements were made before and 5 min after intravenous propranolol (0.5 g/kg) administered over a period of 1 min. In the adult dog, propranolol produced a significant depression of cardiac index and peak LV systolic pressure, significant elevation of systemic resistance index and LV end-diastolic pressure, and a significant fall in indices of myocardial contractility. The changes in heart rate, cardiac index, peak LV systolic pressure, and contractility indices produced by propranolol were 2-4 times greater, on a percentage basis, in the puppies as in the adult dogs. The systemic resistance index and LV end-diastolic pressure changed similarly in both groups. The increased sensitivity of the puppies to propranolol appears to reflect a greater dependence on circulating catecholamines in the immature circulation. Speculation

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Results of systemic to pulmonary arterial shunts during the first year of life are reported in 86 infants under one year of age. Survival rates were highest in older patients and among infants whose basic cardiac defects were considered to be eventually amenable to surgical repair. Persistent hypoxia accounted for the majority of deaths. Congestive heart failure secondary to too large anastomoses occurred in 32.5% of Waterston shunts, but could be successfully managed medically in the majority of patients. Surgical revision of the shunt was accomplished successfully in two infants with subsequent alleviation of symptoms. Congestive heart failure occurred in only one of 26 patients after a Blalock shunt. Ten of the twelve patients in this series survived open-heart repair for cardiac lesions. It will eventually be necessary to compare these data with the results of single stage corrective surgery in the infant group.