Anomalous Origin of the Left Coronary Artery from the Pulmonary Artery

ALCAPA is a rare congenital anomaly, usually an isolated lesion, occurring in 1 in 300,000 live births (Fig. 57-2). The clinical spectrum of ALCAPA is also known as Bland-White-Garland syndrome. Infants with myocardial ischemia typically present with failure to thrive, profuse sweating, dyspnea, pallor, and atypical chest pain upon eating or crying. Malignant arrhythmias leading to sudden cardiac death are the most extreme presentation of myocardial ischemia in ALCAPA. During the neonatal period, high pulmonary vascular resistance ensures antegrade flow from the pulmonary artery through the LCA. However, as this resistance diminishes, there is an eventual reversal of flow, with left-to-right shunting through the pulmonary artery. The result is the phenomenon of “coronary steal,” with LV perfusion becoming dependent on collateral circulation from the RCA.

Figure 57-2 Congenital coronary artery anomalies.

Because infantile circulation has little or no coronary collateral development, ALCAPA leads to severe myocardial ischemia, with resultant LV dysfunction and dilation. Dilation of the left ventricle is due not only to the effects of ongoing myocardial ischemia but also to mitral valve regurgitation, because papillary muscle ischemia is common in ALCAPA. Without surgical intervention and correction of the anomaly, patients die within weeks to months after birth. Patients who survive to adulthood, secondary to the presence and formation of collateral circulation, may remain asymptomatic despite subclinical ongoing ischemia. Arrhythmic sudden death purportedly occurs in 80% to 90% of patients by 35 years of age.

Although ALCAPA is rare, a high index of suspicion should be present for infants presenting with signs of myocardial ischemia or dysfunction. The most frequent confounding diagnosis is dilated cardiomyopathy. Both conditions may present with cardiomegaly, a murmur of mitral insufficiency, and ECG evidence of myocardial ischemia. Two-dimensional echocardiography and coronary angiography typically clarify the diagnosis. Echocardiographic examination alone may be sufficient to achieve diagnosis. If echocardiography reveals an enlarged RCA with global hypokinesis and left ventricle dilation, ALCAPA must be considered in the differential diagnosis. Pulsed and color-flow Doppler examination may delineate a left-to-right shunt. In many but not all cases, two-dimensional echocardiographic evaluation will permit visualization of the anatomic origin of the ALCAPA and assessment of the degree of mitral insufficiency. Though not essential, coronary angiography or ventriculography may be performed if ALCAPA is suspected but not visualized on echocardiography. Coronary angiography also assists in excluding other anatomic etiologies for ischemia and ventricular dysfunction.

Surgical correction remains the gold standard of therapy, but important changes in technique have resulted in improved outcomes. Surgical repair involves direct reimplantation of the anomalous LCA into the aorta by transferring it with a button of pulmonary artery (Fig. 57-3). There are several options to customize the surgical approach so as to overcome anatomic challenges of the length and course of the LCA for reimplantation. In adults, in whom reimplantation is more technically challenging, bypass grafting with the left internal thoracic artery is an equally effective approach.

Figure 57-3 Surgical procedures for correction of congenital coronary artery anomalies.

ALCAPA, anomalous origin of the left coronary artery from the pulmonary artery; LCA, left coronary artery; RCA, right coronary artery; RV, right ventricle.

After reestablishment of a two-coronary system, the previously dilated RCA will generally return to normal size, and the intercoronary collateral network that developed before surgery will regress. Operative mortality for all surgical techniques has markedly decreased. The mortality rate today (5% to 25%), though still high, represents a vast improvement compared with the mortality rates reported in the early 1980s (75% to 80%). No differences in LV function or the late mortality rate have been shown comparing the various reimplantation or revascularization techniques used today. A previous approach, direct ligation of the anomalous coronary, was abandoned because of poor outcomes.

Anomalous Aortic Origin of Coronaries

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