Karuturi Rounds 11 > Alcapa Syndrome

Anomalous Origin of the Left Coronary Artery from the Pulmonary Artery (Bland-White-Garland Syndrome, Alcapa Syndrome)


In anomalous origin of the left coronary artery from the pulmonary artery, the blood supply to the left ventricular myocardium is severely compromised. Soon after birth, as pulmonary arterial pressure falls, perfusion pressure to the left coronary artery becomes inadequate; myocardial ischemia, infarction, and fibrosis result. In some cases, interarterial collateral anastomoses develop between the right and left coronary arteries. Blood flow in the left coronary artery is then reversed, and it empties into the pulmonary artery, a condition known as the “myocardial steal” syndrome. The left ventricle becomes dilated, and performance is decreased. Mitral insufficiency is a frequent complication secondary to a dilated valve ring or infarction of a papillary muscle. Localized aneurysms may also develop in the left ventricular free wall. Occasional patients have adequate myocardial blood flow during childhood and, later in life, a continuous murmur and a small left-to-right shunt via the dilated coronary system (aorta to right coronary to left coronary to pulmonary artery).

Evidence of heart failure becomes apparent within the 1st few months of life, and is often precipitated by respiratory infection. Recurrent attacks of discomfort, restlessness, irritability, sweating, dyspnea, and pallor with or without mild cyanosis occur and probably represent angina pectoris. Cardiac enlargement is moderate to massive. A gallop rhythm is common. Murmurs may be of the nonspecific, ejection type or may be holosystolic due to mitral insufficiency. Older patients with abundant intercoronary anastomoses may have continuous murmurs and minimal left ventricular dysfunction. During adolescence, they may experience angina during exercise. Rare patients with an anomalous right coronary artery may also have such clinical findings.

Roentgenographic examination confirms the cardiomegaly. The electrocardiogram resembles the pattern described in lateral wall myocardial infarction in adults. A QR pattern followed by inverted T waves is seen in leads I and aVL. The left ventricular surface leads (V5 and V6) may also show deep Q waves and exhibit elevated ST segments and inverted T waves . In older patients, an exercise study may be helpful as ST-T wave changes or symptoms occur. Two-dimensional echocardiography can usually suggest the diagnosis; however, echocardiography is not always reliable in diagnosing this condition. On two-dimensional imaging alone, the left coronary artery may appear as though it is arising from the aorta. Color Doppler ultrasound examination has improved the accuracy of diagnosis of this lesion and may demonstrate retrograde flow in the left coronary artery. CT or MRI may be helpful in confirming the origin of the coronary arteries. Cardiac catheterization is diagnostic; aortography shows immediate opacification of the right coronary artery only. This vessel is large and tortuous. After filling of the intercoronary anastomoses, the left coronary artery is opacified, and contrast can be seen to enter the pulmonary artery. Pulmonary arteriography may also opacify the origin of the anomalous left coronary artery. Selective left ventriculography usually demonstrates a dilated left ventricle that empties poorly.

Untreated, death often occurs from heart failure within the 1st 6 mo. Those who survive generally have abundant intercoronary collateral anastomoses. Medical management includes standard therapy for heart failure (diuretics, digoxin, captopril) and for controlling ischemia (nitrates, β-blocking agents).

Surgical treatment consists of detaching the anomalous coronary artery from the pulmonary artery and anastomosing it to the aorta to establish normal myocardial perfusion. A seriously ill infant with a tiny left coronary artery may present a difficult technical problem. Ligation of the anomalous left coronary artery at its origin was once performed to prevent runoff from the coronary circuit and possibly to increase myocardial perfusion by the collateral circulation. As surgical experience with switching coronary arteries in neonates has expanded, this option has largely been abandoned. In patients who have already sustained a significant myocardial infarction, cardiac transplantation may be the best option.