What is ALCAPA and ARCAPA?

ALCAPA does not present prenatally because of the favorable fetal physiology that includes (1) equivalent pressures in the main pulmonary artery and aorta secondary to a nonrestrictive patent ductus arteriosus, and (2) relatively equivalent oxygen concentrations due to parallel circulations.

This results in normal myocardial perfusion and, therefore, no stimulus for collateral vessel formation between the right and left coronary artery systems is present. Shortly after birth, as the circulation becomes one in series, pulmonary artery pressure and resistance decrease, as does oxygen content of pulmonary blood flow. This results in the left ventricular myocardium being perfused by relatively desaturated blood under low pressure, leading to myocardial ischemia.

Initially, myocardial ischemia is transient, occurring during periods of increased myocardial demands, such as when the infant is feeding and crying. Further increases in myocardial oxygen consumption lead to infarction of the anterolateral left ventricular free wall. This often causes mitral valve papillary muscle dysfunction and variable degrees of mitral insufficiency.

Collateral circulation between the right and left coronary systems ensues. Left coronary artery flow reverses and enters the pulmonic trunk due to the low pulmonary vascular resistance (coronary steal phenomena). As a result, left ventricular myocardium remains underperfused. Consequently, the combination of left ventricular dysfunction and significant mitral valve insufficiency leads to congestive heart failure (CHF) symptoms (eg, tachypnea, poor feeding, irritability, diaphoresis) in the young infant. Inadequate myocardial perfusion likely causes significant chest pain and these symptoms of myocardial ischemia may be misinterpreted as routine infantile colic.

ALCAPA is a rare, congenital cardiac anomaly accounting for approximately 0.25-0.5% of all congenital heart disease. The incidence of ALCAPA does not vary geographically. ALCAPA is not considered an inheritable congenital cardiac defect. No risk factors for the occurrence of ALCAPA in any individual family are known, and ALCAPA is not associated with any syndromes or noncardiac conditions.

Left untreated, the mortality rate in the first year of life is 90% secondary to myocardial ischemia or infarction and mitral valve insufficiency leading to CHF. Sudden death may occur because of inadequate collateral circulation between the left and right coronary artery systems.

Approximately 85% of patients present with clinical symptoms of CHF within the first 1-2 months of life. In unusual cases, the clinical presentation with symptoms of myocardial ischemia may be delayed into early childhood. Rarely, a patient may stabilize following infarction and present with mitral valve regurgitation later in childhood or even adulthood.

• Infants with anomalous left coronary artery from the pulmonary artery (ALCAPA) usually do well for a short period then gradually become fussy and irritable. Typically, they may display pallor, irritability, and diaphoresis after feeding, which are often attributed to colic.
• Signs and symptoms of congestive heart failure (CHF), including tachypnea, tachycardia, diaphoresis, and poor feeding, eventually ensue, leading to poor weight gain. Usually no obvious evidence of a systemic illness is noted.
• In rare instances, children outgrow these symptoms and gradually become asymptomatic, although periodic dyspnea, angina pectoris, syncope, or sudden death may still occur in adulthood.

• If CHF is present, the infant appears distressed and exhibits tachypnea, tachycardia, diaphoresis, and irritability.
• Auscultation may demonstrate a systolic murmur of mitral valve regurgitation and, possibly, a diastolic rumble of relative mitral stenosis best located at the apical left precordial region.
• Rarely, a soft continuous murmur may be detected at the upper left sternal border that is reminiscent of a coronary artery fistula or a small patent ductus arteriosus.
• The left ventricular precordial impulse may appear prominent and displaced both inferiorly and laterally.
• The second heart sound may seem narrowly split with increased intensity of the pulmonic component, if left ventricular failure causes pulmonary artery hypertension secondary to elevated left atrial pressure.
• In cases of severe CHF, hepatic enlargement may be observed, and the peripheral pulses may be diminished in intensity secondary to low cardiac output.

• Inheritance is not a factor. For example, if 2 family members are affected, the fact that they are within the same family did not have a role in their development of the condition.
• In utero exposure to teratogens, chromosomal abnormalities, or other risk factors are unrelated to ALCAPA.
• An isolated congenital cardiac defect, including patent ductus arteriosus, ventricular septal defect, tetralogy of Fallot, or coarctation of the aorta, rarely may be associated with ALCAPA. No specific association with any noncardiac anomalies is noted.

• Initial management of anomalous left coronary artery from the pulmonary artery (ALCAPA) is both supportive and temporary. Treatment of congestive heart failure (CHF) includes carefully using diuretics, afterload reduction medications, and inotropic drugs.
• Although systemic oxygen transport may be reduced in the presence of low systemic blood flow, using 100% oxygen may be deleterious. Oxygen may further reduce pulmonary vascular resistance and magnify coronary steal from the right coronary artery into the pulmonary arteries.
• A similar phenomenon occurs with aggressive afterload reduction, during which right coronary artery perfusion may be reduced, leading to decreased left coronary blood flow.
• Inotropic support, on the other hand, may significantly increase myocardial oxygen consumption, which, in the presence of reduced myocardial blood flow, may result in worsening ischemia.
• Increasing reports of catheter intervention for this lesion are emerging. The results in these instances remain conflicting. Surgical intervention remains the procedure of choice.

• Spontaneous resolution of CHF symptoms is rare. Surgical revascularization of the left coronary artery system is usually necessary.
• Once the patient is stabilized, perform surgical revascularization to create a 2 coronary artery system. Over the years, the following techniques have been advocated:

  • Ligation of the left coronary artery at its origin from the main pulmonary artery is an original technique, performed without the use of cardiopulmonary bypass. The long-term results were not optimal since myocardial perfusion remained solely dependent on extensive collateralization from the right coronary artery, and the patient remained at risk for ischemic episodes and sudden death.
  • Current surgical procedures are directed at establishing revascularization by creating a 2 coronary artery system via either (1) a left subclavian artery-coronary artery anastomosis, (2) a saphenous vein bypass graft, (3) Takeuchi procedure (creation of an aortopulmonary window and an intrapulmonary tunnel extending from the anomalous ostium to the window), or (4) direct reimplantation.By establishing a patent 2 coronary artery system, most patients experience normalization of left ventricular systolic function, thereby improving long-term survival.
  • The need for simultaneous mitral valve reconstruction, in the presence of severe insufficiency, is controversial because spontaneous improvement of mitral valve function often occurs following surgical revascularization.
  • Once revascularization to a 2 coronary artery system is accomplished, most patients demonstrate improved left ventricular systolic function, decreased mitral valve insufficiency, and resolution of CHF symptoms. In many cases, the classic infarct pattern on electrocardiography eventually disappears following normalization of left coronary blood flow. Occasionally, persistent refractory mitral regurgitation will necessitate delayed mitral valve repair or replacement.