Anomalous Left Coronary Artery From the Pulmonary Artery, Surgical Treatment 

Early surgical attempts at repair of an anomalous left coronary artery from the pulmonary artery (ALCAPA) were palliative. In 1953, Potts proposed an aortopulmonary anastomosis to increase oxygen saturation in the main pulmonary artery. Also in 1953, Mustard described a left carotid artery–to–anomalous left coronary artery procedure.^[1] In 1959, Sabiston et al proposed simple ligation of the proximal origin of the anomalous left coronary artery.^[2] In 1966, Cooley et al used saphenous vein grafting from the aorta to the anomalous left coronary artery.^[3] In 1968, Meyer et al described a left subclavian artery–to–anomalous left coronary artery repair.^[4]

An internal mammary artery–to–anomalous left coronary artery from the pulmonary artery procedure has also been performed. Pulmonary artery banding has been attempted to increase perfusion pressure in the anomalous left coronary artery from the pulmonary artery. In addition, procedures to increase collateral circulation, such as poudrage and de-epicardialization, have been tried.

Each of the above procedures has fallen out of favor. Today, establishing a system with 2 coronary arteries is the goal in definitive surgical repair.

Direct anastomosis of the anomalous left coronary artery from the pulmonary artery directly to the aorta was described in the 1970s and currently remains the procedure of choice. The experience gained in coronary artery transfer during the arterial switch operation has facilitated techniques for coronary transfer to repair the anomalous left coronary artery from the pulmonary artery. In most patients, the anomalous left coronary artery is situated in a position that allows for direct transfer of the anomalous coronary artery. For patients in whom direct transfer of the coronary artery is not feasible, performing the novel repair of creating an intrapulmonary aortocoronary tunnel may be appropriate, as described by Takeuchi in 1979.

Occasionally, cardiac transplantation has been required in patients with anomalous left coronary artery from the pulmonary artery with severe cardiac dysfunction.

The origin of the left main coronary artery is anomalous. The left main coronary artery abnormally originates from the pulmonary artery. Although rare, this is a very significant lesion that requires prompt recognition and diagnosis. With early diagnosis, prognosis is excellent after surgical repair.

Frequency

Anomalous left coronary artery from the pulmonary artery is rare in the United States, affecting 1 in 300,000 live births. Anomalous left coronary artery from the pulmonary artery represents approximately 0.25-0.5% of congenital heart defects.

No data are available to suggest variance in the frequency of anomalous left coronary artery from the pulmonary artery in different countries or between social, economic, or ethnic groups.

The coronary arterial circulation is established by 45 days' gestation in the fetus. Anomalous left coronary artery from the pulmonary artery is caused either by abnormal division of the conotruncus or by abnormal involution of endothelial buds that are present on all 6 sinuses of Valsalva of the great vessels. Usually, all but 2 of the endothelial buds involute, leaving 2 buds in the aortic sinuses to eventually become the coronary arteries. With anomalous left coronary artery from the pulmonary artery, an endothelial bud sometimes persists on a pulmonary sinus and attaches to the developing left main coronary artery. The left coronary artery can also connect to other locations in the pulmonary artery and has even been reported to connect to one of the branch pulmonary arteries.

Anomalous left coronary artery from the pulmonary artery usually occurs as an isolated defect; however, it has been associated with congenital defects, including ventricular septal defect, patent ductus arteriosus, and coarctation of the aorta. One case report has documented anomalous left coronary artery from the pulmonary artery in a patient with hypoplastic left heart syndrome.

The pathophysiology of anomalous left coronary artery from the pulmonary artery varies and depends on the patient's age, the pulmonary vascular resistance/pressure, the presence of collateral vessels between the right and left coronary artery systems, and the degree of myocardial ischemia. Four physiologic stages have been described, as follows:

• Stage 1: In the fetal and early neonatal period, pulmonary vascular resistance is high and pulmonary artery pressure is equal to the aorta pressure. Saturation and perfusion in the anomalous left coronary artery from the pulmonary artery are adequate, and no obvious myocardial ischemia or impairment of left ventricular function is observed.
• Stage 2

  • During the first days to weeks of neonatal life, pulmonary vascular resistance normally decreases. The drop in pressure is inadequate to provide prograde flow into the anomalous left coronary artery from the pulmonary artery.
  • Flow to the left coronary system is provided by collateral flow from the right coronary artery system. At this time, flow in the anomalous left coronary artery from the pulmonary artery is retrograde.
  • Collateral flow from the right coronary artery system meets the high resistance of the left ventricular myocardial bed, and preferential flow occurs into the low-resistance pulmonary artery. This leads to left ventricular myocardial ischemia, and, at this time, infants may present with clinical signs of myocardial ischemia.
  • With the retrograde flow of fully saturated blood into the pulmonary artery, a small left-to-right shunt may be present, detected on cardiac catheterization by a "step up" in oxygen saturation in the pulmonary artery. Usually, the shunt is minimal, and the ratio of pulmonary blood flow (Qp) to systemic blood flow (Qs) ranges from 1-1.5.
• Stage 3: Rarely, a large collateral circulation may be located between the right and left coronary systems, which may provide adequate myocardial perfusion, allowing infants to have little or no clinical difficulties. These extensive collateral vessels can provide enough coronary flow to allow patients to live to adulthood.
• Stage 4: In the final stage, collateral flow is inadequate, retrograde flow into the pulmonary artery persists, and myocardial steal continues. At this stage, adults may present with signs of myocardial ischemia.

Myocardial ischemia occurs in an anterolateral distribution, causing global left ventricular dilation and dysfunction. Mitral valve regurgitation is common secondary to papillary muscle infarction, mitral annular dilation, or both. Left atrial dilation and pulmonary venous congestion ensue, adding congestive symptoms to those of angina pectoris.

Historically, the defect was termed Bland-Garland-White syndrome. In 1933, Bland et al first eloquently described the clinical presenting signs in infants with anomalous left coronary artery from the pulmonary artery. The following description is of a 10-week-old infant:

…while nursing from the bottle, the onset of an unusual group of symptoms occurred, which consisted of paroxysmal attacks of acute discomfort precipitated by the exertion of nursing. The infant appeared at first to be in obvious distress, as indicated by short expiratory grunts, followed immediately by marked pallor and cold sweat with a general appearance of severe shock. Occasionally, with unusually severe attacks, there appeared to be a transient loss of consciousness…^[5]

Infants present with respiratory distress, feeding intolerance, or failure to thrive. In the rare case involving an older child or adult, the patient may have exertional chest pain, dyspnea, or syncope. Unfortunately, sudden death occurs in some patients following exertion.

Upon physical examination, infants have an enlarged heart and displaced apical impulse. A gallop rhythm or the holosystolic murmur of mitral regurgitation may be present. Signs of congestive heart failure may be apparent.

The clinical signs of anomalous left coronary artery from the pulmonary artery are nonspecific. Myocarditis and cardiomyopathy are other considerations in infants presenting with left ventricular dilation and heart failure. Careful evaluation for the presence of anomalous left coronary artery from the pulmonary artery is necessary in any infant presenting with left ventricular dilation and heart failure.

Demonstration of the lesion and diagnosis of anomalous left coronary artery from the pulmonary artery (ALCAPA) are an indication for surgical intervention. Prompt preparations should be made for surgical repair. Medical therapy provides a bridge to surgery and should be used to optimize the hemodynamics in the patient during the preoperative period.

In most patients, the anomalous left coronary artery originates from the posterior or leftward sinus of the pulmonary artery. Less commonly, the anomalous coronary artery arises from the right pulmonary artery. The branching of the anomalous left coronary artery is usually normal with normal left anterior descending and circumflex coronary arteries. The origin of the right coronary artery is normal; however, this vessel is usually enlarged and tortuous.

Very few contraindications for surgical repair of left coronary artery from the pulmonary artery (ALCAPA) have been identified. Even in patients with severe disease and poor left ventricular function, revascularization after repair of anomalous left coronary artery from the pulmonary artery usually results in improved left ventricular function. Contraindications for surgical repair include multisystemic end-organ failure and a poor prognosis for survival with or without surgical intervention for the anomalous left coronary artery from the pulmonary artery.