ALCAPA (anomalous left coronary artery origin from pulmonary artery), Bland-White-Garland syndrome

Definition

In Bland-White-Garland syndrome, also known as ALCAPA (anomalous left coronary artery origin from pulmonary artery), the left (or right) pulmonary artery originates anomalously from the pulmonary trunk (in rare cases from the right or left pulmonary artery). This is a very rare congenital heart defect (1 per 300,000 live births) and, without surgical intervention, the lethality rate in the first year of life is 35-80%.

Pathophysiology and Clinical Symptoms

Following the postnatal fall in the pulmonary vascular resistance the perfusion pressure in the coronary artery with the anomalous origin also falls. Through the flow reversal in the left coronary artery (LCA) a coronary steal mechanism arises so that the perfusion of the left ventricle depends on collateral vessels from the right coronary artery (RCA). The consequences may include myocardial ischemia leading to infarction, left ventricular dysfunction with possible secondary mitral valve insufficiency and ventricular arrhythmia. In most cases the children show symptoms after the fall in pulmonary vascular resistance at the age of 1-6 months. The main symptoms of myocardial ischemia and heart failure are angina pectoris, shortness of breath, increased perspiration, feeding problems and susceptibility to infections. The clinical manifestation and the extent of myocardial necrosis depend on the pulmonary vascular resistance, the speed of ductus closure and the development of coronary collaterals. Between 10% and 15% of the patients have good collateralization and develop symptoms only as adults. However, this patient cohort has an elevated risk of sudden cardiac death.

Diagnosis

  • by ECG: evidence of left ventricular myocardial ischemia (Pardee Q, R loss, ST segment changes).
  • by chest X-ray: cardiomegaly (cardiothoracic ratio > 0.5), pulmonary vascular congestion.
  • by echocardiography: impairment of left ventricular pumping function (LVEDD, LVEF, LVFS), mitral valve insufficiency, dilatation of the right coronary artery, retrograde blood flow from the left coronary artery into the pulmonary artery (PA), origin of the LCA from the PA.
  • by heart catheterization: imaging of the coronary arteries (retrograde contrast medium flow from the RCA into the LCA and PA), reduced ventricular function, elevated LVEDP.

Indication

The diagnosis is at the same time the indication for surgical correction. Severe LV dilatation may make postoperative ECMO support necessary.

Operation

The surgical procedure of choice is restoration of dual coronary artery circulation by re-implantation of the anomalously originating coronary artery into the aorta. Surgical access is by a median thoracotomy and the heart-lung machine is used. The pulmonary arteries are snared with tourniquets. Next the aorta is clamped and the heart is arrested by cardioplegia. The pulmonary artery is incised and the anomalously originating coronary artery is identified and excised as a button. The coronary artery is mobilized and placed directly into the ascending aorta. The pulmonary artery is reconstructed with autologous pericardium. Severe mitral valve insufficiency (grade III-IV) is corrected during the operation. Slight to moderate mitral valve insufficiency usually resolves after regeneration of the myocardium. 

Possible Intraoperative Complications

Due to the left ventricular dysfunction, weaning from the heart-lung machine may require inotropic support in high doses or the implantation of a left ventricular assist device. Preoperative LVEF ≤ 37%, LV-FS ≤ 15% and LVEDP ≥ 18 mmHg are indicators for the perioperative placement of mechanical circulatory support systems.

Possible Long-Term Complications

The prognosis of the child who undergoes surgery by today’s standards is good in the short and mid-term. Usually the function of the left ventricle recovers almost entirely and the patients reach normal exertion tolerance. Mitral valve insufficiency arising from the left ventricular dilatation may make valve reconstruction or replacement necessary during the further course.

Recommendations for Further Treatment

We recommend prophylactic antibiotic treatment for the known indications if there are residual defects or the mitral valve insufficiency is still hemodynamically relevant.