Abnormal Origin Of Right Or Left Pulmonary Artery From The Aorta

A rare, congenital, heart malformation characterized by anomalous origin of one branch of the pulmonary arteries directly from the aorta and a normal origin of the other pulmonary artery from the main pulmonary artery coming from the right ventricular outflow tract. Patients present respiratory distress, congestive heart failure and failure to thrive within the first days/months of life.

Epidemiology

The incidence is estimated at 0.1% of all congenital cardiac anomalies.

Clinical description

Abnormal origin of right or left pulmonary artery from aorta usually occurs in infants or in the newborns where it manifests by respiratory distress, recurrent respiratory infection, moderate to severe pulmonary hypertension, congestive heart failure, and failure to thrive within the first months of life. Infants are usually cyanotic and may present chest pain and dyspnea on exertion. Two forms may be distinguished: anomalous origin of the left pulmonary artery from the aorta (AOLPA; about 25% of cases) and anomalous origin of the right pulmonary artery from the aorta (AORPA; about 75% of cases). Abnormal origin of right or left pulmonary artery from aorta frequently occurs as an isolated form with or without patent arterial duct. However, AOLPA may be associated with Tetralogy of Fallot, Right aortic arch, aortopulmonary window and anomalous subclavian arteries. On the contrary, patent ductus arteriosus and aortic coarctation or interruption (type A) may be associated with AORPA. Atrial and ventricular septal defects may be also present.

Etiology

The pathogenesis still remains unknown, although an association has been reported with 22q11.2 deletion syndrome in children with AOLPA, usually associated with Right aortic arch, Tetralogy of Fallot and Absent pulmonary valve. Indeed, deletions 22q11.2 may impair the second heart field causing anomalies of development of the pharyngeal pouch derivate, aortic arches and conotruncal part of the heart.

Diagnostic methods

Initial diagnosis is made with 2D-echocardiography which allows the definition of morphology and the detection of systemic or supra-systemic pressures in the right ventricle. Diagnosis is confirmed by catheterization, angiocardiography, MRI and CT angiography.

Differential diagnosis

Occasionally, one pulmonary artery (more frequently the left one) can origin via a patent ductus arteriosus coming from the aorta, however this morphological anomaly should be differentiated from Abnormal origin of right or left pulmonary artery from aorta.

Genetic counseling

Abnormal origin of right or left pulmonary artery from aorta is usually non-syndromic and sporadic. However, association with the 22q11.2 deletion syndrome is described in patients with AOLPA. Familial recurrence has also been reported.

Management and treatment

Early diagnosis and surgical treatment are mandatory in order to prevent cardiac failure and pulmonary hypertension. Treatment involves different techniques to implant the anomalous pulmonary artery branch to the main pulmonary artery. This includes direct implantation, end-to-end anastomosis with a synthetic graft, homograft patch, and an "aortic-ring" flap. In cases with AOLPA, the direct implantation technique is the strategy of choice, while for AORPA, different technique employing autologous tissues for increasing the length of the pulmonary artery branch may be used. Postoperative restenosis across the anastomotic site is frequently observed. Postoperative echocardiographic study is thus recommended to detect presence of stenosis.

Prognosis

Patients treated early in life have good short and long-term outcome. If left untreated, the disease may lead to congestive cardiac failure and pulmonary hypertension, with 30% of infants dying within 3 months. Palliative treatment such as pulmonary artery banding, ligation of the associated ductus arteriosus and aortopulmonary shunt, increases mortality substantially.