An infant in difficulty in the first days of life because of heart disease has the potential for rapid deterioration. Too often, the baby looks as though he will survive but is near death hours later. The earlier symptoms appear, the faster deterioration can take place. By the time the infant has
reached 1 or 2 months of age, concern about sudden shifts in status is less warranted.

Infants who present with severe cyanosis (See Color Plate) in the first days to weeks of life may do so because right ventricular outflow is critically obstructed and adequate pulmonary blood flow is dependent on a closing ductus arteriosus, or because the great arteries are transposed and adequate mixing of the pulmonary and systemic circulations is decreasing as the ductus arteriosus constricts. Babies with congestive heart failure in the first week of life often have obstructed left ventricular or aortic outflow, with descending aortic flow supplied by a closing ductus arteriosus. In these babies, survival may depend on persistent patency of the ductus arteriosus; dependency should be suspected, and prostaglandin E1 therapy considered. If possible, echocardiography should be used to confirm a specific anatomic diagnosis, but this may not be available in many primary care facilities, and the infant’s condition may not provide the time before starting treatments to transport to a facility in which echocardiography is available. If a duct-dependent anomaly is suspected from physical examination, ECG, and chest radiograph (e.g., pulmonary atresia, hypoplastic left heart syndrome), or if the condition of a baby with undiagnosed cardiac anomaly is significantly worsening so that arterial oxygen saturation is less than 70% (e.g., as in d-transposition of the great arteries or critical pulmonary stenosis) or there is severe congestive heart failure because of ductal closure (e.g., as in critical aortic stenosis or coarctation), prostaglandin E1 therapy should be initiated even if echocardiography is not available (see Fig. 33-12). The usual starting dose of 0.1 mg/kg/min can frequently be reduced to 0.05 to 0.02 mg/kg/min after stabilization. The occurrence of relatively common side effects, particularly central apnea, vasodilation with hypotension, and fever should be anticipated. Endotracheal intubation should be performed prior to transport in infants receiving prostaglandins, to reduce the risk should later-onset apnea occur.

Despite prostaglandin therapy, these critically ill infants may have low cardiac output that may respond to the correction of common metabolic perturbations including hypothermia, intravascular hypovolemia, hypocalcemia, and hypoglycemia, but frequently, inotropic support is needed (Tables 33-10 and 33-11). Measurement of pressure in a central venous catheter may guide fluid therapy and permit administration of concentrated infusions of dextrose, calcium, and vasoactive amines. After appropriate steps to correct contributing metabolic abnormalities, fluid can be given in 5- to 10-mL/kg doses until adequate response is achieved or circulatory congestion occurs. Infusion of dopamine or dobutamine (5 to 20 mg/kg/min) or amrinone, should be added to support pump function as needed. Higher doses or continuous infusion of epinephrine can be considered to support refractory neonates until surgical palliation can be achieved. Digitalis preparations are much less desirable for acute inotropic support of critically ill infants who have variable renal and hepatic functions and electrolyte status.

Hyperventilation should be avoided in babies with certain lesions in which the pulmonary and systemic circulations are in parallel, such as hypoplastic left heart syndrome. Hyperventilation and oxygen administration in these babies can drop pulmonary vascular resistance to low levels, resulting in runoff into the pulmonary vasculature, systemic hypotension, and very low systemic blood flow.

The acyanotic cardiac infant who develops symptoms of increased respiratory work and poor feeding after 2 to 4 weeks of life often has congestive heart failure from decreasing pulmonary vascular resistance and increasing left-to-right shunt. Treatment with digoxin, diuretics, and, in refractory cases, systemic vasodilators is often indicated (see Table 33-10). Rarely, these infants have left-sided obstructive lesions or myocardial disease (e.g., anomalous left coronary artery) that requires different treatment (see Therapeutic Catheterization).