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Congenital anomaly of the left coronary artery.

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Anomalous Left Coronary Artery from the Pulmonary Artery; ALCAPA.

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1:300,000 live births (0.25-0.5% of all cardiac malformations).

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Not an inherited disorder.

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Because the left coronary artery arises from the pulmonary trunk, perfusion of the left heart must be provided by the pulmonary artery or from collaterals of the right coronary artery. Myocardial perfusion remains normal in the early neonatal period when pulmonary pressure is high. As pulmonary pressure and resistance decrease by 1 to 2 months of age, myocardial perfusion becomes insufficient and ischemia or even myocardial infarction with global ventricular failure occurs. Depending upon the importance of collateral vessels between the right and left coronary arteries, left-to-right shunting of oxygenated blood from the right coronary artery to the left coronary artery and into the pulmonary artery may create a “myocardial steal,” resulting in increased ischemic insult to the anterolateral myocardium with global left ventricular dilatation and dysfunction. Papillary muscle infarction and/or mitral annular dilatation may result in secondary mitral valve regurgitation. Left atrial dilation and finally pulmonary venous congestion ensue, adding congestive symptoms to those of angina pectoris.

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Infants present with respiratory distress, feeding intolerance, and failure to thrive. Congestive heart failure in an infant with either no murmur on auscultation or the murmur of mitral insufficiency is suspicious for ALCAPA. The electrocardiogram may reveal anterolateral myocardial ischemia or infarction. Thallium myocardial perfusion scintigraphy or echocardiography assists in the diagnosis of this specific malformation. Aortic angiography provides the final confirmation and is a good tool for assessing the collateral vessels. The diagnosis is generally made during the first year of life, but occasionally may become manifest later in childhood or even in adulthood. Sudden death has been reported in these patients following exertion.

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Rapidly progressive deterioration of physical condition, including dyspnea, expectorations, perspiration, tachycardia, and refusal to drink with failure to thrive. The patient may have angina pectoris associated with feeding. It has been estimated that 90% of untreated patients die in the first year of life. The lesion is sometimes discovered during investigation for heart murmur (although a murmur is not a constant finding) or chest pain in late childhood or adulthood.

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Obtain full history of cardiopulmonary symptoms of the patient. Evaluate cardiac function with electrocardiogram, chest radiography, echocardiography, left cardiac catheterization, and coronary angiography (ejection fraction, left ventricular diameter, pulmonary artery pressure and saturation, arterial saturation).

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Symptomatic infants undergoing surgery to correct their coronary anomaly will have pulmonary venous congestion, a diminished cardiac output, decreased contractility as a result of chronic ischemia of the myocardium, and, frequently, myocardial infarction and some degree of subendocardial fibrosis. Avoid factors that reduce pulmonary vascular resistance (alkalosis, hypocapia, hyperoxia), since this may result in increased coronary steal. There is a high risk of ventricular arrhythmias. The clinical condition ...

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