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At a glance

Congenital anomaly of the origin of the left coronary artery.

Synonyms

Anomalous Left Coronary Artery from the Pulmonary Artery (ALCAPA) Syndrome; ALPACA Syndrome.

History

Named after the three American physicians Edward F. Bland, Paul D. White, and Joseph Garland who described the disease in 1933 in a 3-month-old boy who died from this condition. However, the disease has been described before.

Incidence

1:300,000 live births (accounting for 0.25-0.5% of all cardiac malformations). Males appear to be affected more often.

Genetic inheritance

This is not an inherited disorder.

Pathophysiology

The left coronary artery arises from the main pulmonary artery (most commonly from the left pulmonary sinus of Valsalva and very rarely from the right pulmonary artery), thus perfusion of the left heart must be provided by the pulmonary artery or from collaterals of the right coronary artery. Myocardial perfusion depends on the gradient between systemic and pulmonary arterial pressure (PAP) and the presence or absence of intercoronary collateral vessels between the left and right coronary artery systems. Myocardial perfusion remains normal in the early neonatal period when the PAP is still high. As PAP and pulmonary vascular resistance decrease over the first 2 months of life, myocardial perfusion becomes insufficient and ischemia or even myocardial infarction with global ventricular failure occurs. Depending upon the development 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,” which in combination with the decreased coronary perfusion pressure will result in increased risk for ischemic insult to the anterolateral myocardium with global left ventricular dilatation and dysfunction. Papillary muscle infarction and/or mitral annular dilatation may lead to secondary mitral valve regurgitation. Left atrial dilation and finally pulmonary venous congestion ensue, adding congestive symptoms to those of angina pectoris. Pulmonary venous congestion will lead to increased PAP, which theoretically will reduce coronary steal from the right to the left coronary artery.

Diagnosis

Infants present with respiratory distress, tachycardia, sweating, 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 chest x-ray typically shows cardiomegaly with pulmonary venous congestion and/or signs of pulmonary edema. The electrocardiogram may show signs of anterolateral myocardial ischemia or infarction. Echocardiography can be used to diagnose this specific malformation, but also reveal the dilatation and poor function of the left ventricle often in combination with mitral regurgitation due to papillary muscle ischemia/infarction. Cardiac catheterization with aortic angiography is considered the gold standard as it provides the final confirmation and assessment ...

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