Anomalous left coronary artery from the pulmonary artery

Anomalous left coronary artery from the pulmonary artery (ALCAPA), also known as Bland-White-Garland syndrome (BWG), is a rare congenital coronary artery anomaly and is considered one of the most severe of such anomalies.

There are two forms, based on onset of disease, each of which has different manifestations and outcomes 5:

  • infantile type
    • infants experience myocardial infarction and congestive heart failure
    • 90% die within the 1st year of life
  • adult type
    • manifests in adults
    • results in chronic myocardial ischaemia and dysrhythmias
    • a cause of sudden cardiac death

This abnormality only accounts for 0.25-0.5% of all congenital cardiac anomalies 3.

It is most often an isolated anomaly, associated with other cardiac anomalies in only ~5% of cases 3,7:

In the infantile type, ALCAPA presents typically when infants are 1-2 months old (see Pathology below).

ALCAPA refers to a cardiovascular anomaly where the left main coronary artery arises from the pulmonary trunk instead of the left coronary sinus of the ascending aorta.

Either of two etiologies can be responsible for ALCAPA:

  • the bulbus cordis undergoes abnormal septation into the aorta and pulmonary trunk
  • persistence of the pulmonary buds with concomitant involution of the aortic buds that are precursors of the coronary arteries

During the first month of life, physiologic pulmonary hypertension tends to preserve antegrade blood flow within the left coronary artery, and infants usually remain asymptomatic. Shortly thereafter, pulmonary artery pressure, resistance, and oxygen content decrease. Thus, the left ventricle receives blood with low oxygen content at low pressure, causing myocardial ischemia. Further increases in myocardial oxygen consumption ensue in infarction of the anterolateral left ventricular free wall, often with resultant mitral valve insufficiency. These events stimulate the development of a collateral circulation from the right pulmonary artery to the anomalous left coronary circulation. Diminished pulmonary vascular resistance results in flow reversal in the left coronary artery into the pulmonary trunk (i.e. coronary steal phenomenon). Congestive heart failure (CHF) is the end result of left ventricular dysfunction in combination with significant mitral insufficiency.

ECG-gated cardiac CT allows direct visualisation of anomalous left main coronary arterial origin from the posterior aspect of the pulmonary artery. The right coronary artery may be unusually dilated and tortuous with evidence of collateral formation. Intercoronary collateral arteries along the external surface of the heart or within the interventricular septum may also be seen.

Prognosis depends significantly on the extent of collateral formation, however, most infants die within the 1st year of birth 4. Death is usually due to circulatory insufficiency from left ventricular dysfunction or mitral valve incompetence, myocardial infarction, or life-threatening cardiac dysrhythmias 3. Early surgical repair is potentially curative. The Takeuchi procedure involves the creation of an aortopulmonary window and an intrapulmonary tunnel that baffles the aorta to the ostium of the anomalous left coronary artery.

Congenital coronary artery anomalies
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Article information

rID: 9750
Synonyms or Alternate Spellings:
  • ALCAPA
  • Bland-White-Garland syndrome
  • Bland-White-Garland syndrome (BWG)
  • ALCAPA syndrome
  • Anomalous origin of the left coronary artery from the pulmonary artery

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    Case 1: with dilated cardiomyopathy
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    Case 2: cardiac CT with ALCAPA
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