Hypoplastic left heart syndrome accounts for 1% of all congenital heart defects (Fig. 144-6) but is the most common cause of death from cardiac defects in the first month of life. Hypoplastic left heart syndrome occurs when there is failure of development of the mitral or aortic valve or the aortic arch. A small left ventricle that is unable to support normal systemic circulation is a central finding, regardless of etiology. Associated degrees of hypoplasia of the ascending aorta and aortic arch are present. Left-to-right shunting occurs at the atrial level.
The newborn is dependent on right-to-left shunting at the ductus arteriosus for systemic blood flow. As the ductus arteriosus constricts, the infant becomes critically ill with signs and symptoms of heart failure from excessive pulmonary blood flow and obstruction of systemic blood flow. Pulses are diffusely weak or absent. S2 is single and loud. There is usually no heart murmur. Cyanosis may be minimal, but low cardiac output gives a grayish color to the cool, mottled skin.
CNS abscess Right-to-left shunting Antibiotics, drainage
Gingival disease Polycythemia, gingivitis, bleeding Dental hygiene
Gout Polycythemia, diuretic agents Allopurinol
Arthritis, clubbing Hypoxic arthropathy None
Pregnancy Poor placental perfusion, poor ability to increase cardiac output Bed rest
Infectious disease Associated asplenia, DiGeorge syndrome Antibiotics
Fatal RSV pneumonia with pulmonary hypertension Ribavirin, RSV immune globulin
Growth Failure to thrive, increased oxygen consumption, decreased Treat heart failure; correct defect early nutrient intake
Psychosocial adjustment Limited activity, peer pressure; chronic disease, multiple Counseling hospitalizations, cardiac surgical techniques
CNS, Central nervous system; RSV, respiratory syncytial virus.
ECG findings include right ventricular hypertrophy with decreased left ventricular forces. The chest x-ray reveals car
Figure 145-1 Ventricular function curve illustrating the effect of inotropic agents or arterial vasodilators. In contrast to diuretics, the effect of digitalis or arterial vasodilator therapy in a patient with heart failure is movement onto another ventricular function curve intermediate between the normal and the depressed curves. When the patient’s ventricular function moves from A to B by the administration of one of these agents, the left ventricular end-diastolic pressure may also decrease because of improved cardiac function; further administration of diuretics or venodilators may shift the function further to the left along the same curve from B to C and eliminate the risk of pulmonary edema. A vasodilating agent that has arteriolar and venous dilating properties (e.g., nitroprusside) would shift this function directly from A to C. If this agent shifts the function from A to D because of excessive venodilation or administration of diuretics, the cardiac output may decrease too much, even though the left ventricular end-diastolic pressure would be normal (10 mm Hg) for a normal heart. Left ventricular end-diastolic pressures of 15 to 18 mm Hg are usually optimal in the failing heart to maximize cardiac output, but to avoid pulmonary edema. (From Andreoli TE, Carpenter CCJ, Griggs RC, Loscalzo J, editors: Cecil essentials of medicine, ed 5, Philadelphia, Saunders, 2001.) pulmonary edema. Echocardiographyshows the small left side of the heart, the degree of stenosis of theaortic and mitral valves, the hypoplastic ascending aorta, and the adequacy of left-to-right atrial flow and right-to-left ductal flow.