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 :

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

Epidemiology

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

Associations

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

• atrial septal defect (ASD)
• ventricular septal defect (VSD)
• patent ductus arteriosus (PDA)
• coarctation of the aorta
• tetralogy of Fallot (TOF)

Clinical presentation

In the infantile type, ALCAPA presents typically when infants are 1-2 months old. Presenting complaints are typically nonspecific and include diaphoresis, irritability, wheezing and respiratory distress. Precordial auscultation may reveal a murmur.

ECG

• deep (>5 mm), narrow Q waves
  • typically in the lateral leads I, aVL, V5-6
  • most suggestive feature on the ECG, but may be absent in up to 45% of patients
• high left ventricular voltage
  • meeting voltage criteria of left ventricular hypertrophy
  • characteristic of adolescents and older children 
  • may be accompanied by left axis deviation
• poor R wave progression
  • defined by an R wave height <3 mm in lead V3

Pathology

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.

Etiology

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

Pathophysiology

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 in approximately 80-85% of cases (infantile type). However in 10-15% of patients, these events stimulate the development of collateral circulation from the right coronary artery to the anomalous left coronary circulation, thus these patients can reach adulthood, the disease most commonly manifesting as late-onset rhythm disorders due to the altered cardiac electric currents. 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.

Radiographic features

Cardiac CT

ECG-gated cardiac CT allows direct visualization 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.

Treatment and prognosis

Prognosis depends significantly on the extent of collateral formation, however, most infants die within the first year of birth . Death is usually due to circulatory insufficiency from left ventricular dysfunction or mitral valve incompetence, myocardial infarction, or life-threatening cardiac dysrhythmias . 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.

Siehe auch:

• Aortenisthmusstenose
• Atriumseptumdefekt
• Normvarianten Koronararterien
• Herzfehler
• atypischer Verlauf der Koronararterien
• rechte Koronararterie
• Ventrikelseptumdefekt
• anomalous left main coronary arterial origin
• anomalous right coronary artery from the pulmonary artery (ARCAPA)

und weiter:

• Varianten der Herzanatomie
• linke Koronararterie
• Fistel zwischen Koronararterie und Pulmonalarterie
• überkreuzender Ursprung der Pulmonalarterien