Anomalous Left Coronary Artery From the Pulmonary Artery

Updated: Jan 17, 2017
  • Author: Mary C Mancini, MD, PhD, MMM; Chief Editor: Syamasundar Rao Patnana, MD  more...
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Overview

Background

Anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) is a rare but serious congenital cardiac anomaly.

ALCAPA was first described in 1866. The first clinical description in conjunction with autopsy findings was described by Bland and colleagues in 1933, so the anomaly is also called Bland-White-Garland syndrome. [1]  In 1962, Fontana and Edwards reported a series of 58 postmortem specimens that demonstrated that most patients had died at a young age. [2]

Presently, the prognosis for patients with ALCAPA is dramatically improved as a result of both early diagnosis using echocardiography with color flow mapping and improvements in surgical techniques, including myocardial preservation.

The ALCAPA anomaly may result from (1) abnormal septation of the conotruncus into the aorta and pulmonary artery, or from (2) persistence of the pulmonary buds together with involution of the aortic buds that eventually form the coronary arteries.

ALCAPA is usually an isolated cardiac anomaly but, in rare incidences, has been described with patent ductus arteriosus, ventricular septal defect, tetralogy of Fallot, and coarctation of the aorta. Extremely rare variations of anomalous origin of the coronary arteries from the main pulmonary artery include the following:

  • The left anterior descending or circumflex branches
  • The right coronary, often discovered as an incidental finding on autopsy
  • Both the right and left coronary arteries, a circumstance not compatible with survival
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Pathophysiology

Anomalous origin of the left coronary artery from the pulmonary artery (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 similar 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; low pressure is more important in causing decreased myocardial perfusion.

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. [3]

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Etiology

Inheritance is not a factor for anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA). For example, if two family members are affected, the fact that they are within the same family did not have a role in their development of the condition. The condition is generally considered to be on the basis of multifactorial inheritance, similar to other congenital heart defects.

In utero exposure to teratogens, chromosomal abnormalities, or other risk factors are unrelated to ALCAPA.

Other congenital cardiac defects, such as 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. [4]

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Epidemiology

United States data

Anomalous origin of the left coronary artery from the pulmonary artery (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.

Race-, sex-, and age-related demographics.

There is no known racial predilection.

The occurrence of ALCAPA is generally similar between males and females, and it is not considered an inheritable congenital cardiac defect.

Approximately 85% of patients present with clinical symptoms of congestive heart failure (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.

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Prognosis

Mortality/Morbidity

Early diagnosis using echocardiography with color flow mapping and improvements in surgical techniques (eg, myocardial preservation) dramatically improve prognosis.

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 and/or development of arrhythmia.

Complications

Complications are rare. The need for future valve surgery depends on the occurrence of hemodynamic complications (eg, residual mitral valve insufficiency precipitated by permanent damage of the mitral valve architecture) following surgery.

Late complications related to coronary artery insufficiency are more likely to occur if revascularization was accomplished by any of the following:

  • Surgical ligation
  • Bypass grafts that may become occluded or stenotic
  • Intrapulmonary tunnel technique, which may cause supravalvar pulmonary stenosis or, less commonly, become obstructed at the surgically created aortopulmonary window

Inadequate growth of the coronary anastomosis is possible, although unlikely, if surgical reimplantation of the left coronary artery was performed. This occurrence is similar to the rare reports of late coronary artery problems following the arterial switch procedure for transposition of the great vessels that also requires direct coronary transfer and reimplantation.

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Patient Education

All patients should undergo formal exercise stress testing at an appropriate age as an aid in determining an appropriate exercise program.

Long-term physical restrictions, including restrictions of participation in competitive sports, are a direct function of whether myocardial ischemia is evident at rest or during exercise.

No dietary restrictions are necessary following successful surgical revascularization with subsequent clinical improvement.

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