Congenital Descending Aorta-Pulmonary Vein Fistula

Congenital descending aorta-pulmonary vein fistula (cDAPVF) is a very rare congenital fistula between the descending aorta and the pulmonary vein. In this article, we present a young male patient who was admitted to our department with hemoptysis. A contrast-enhanced computed tomography (CT) scan confirmed the diagnosis, and the patient underwent surgical ligation of the abnormal artery. To our knowledge, less than 10 cases have been previously reported, and this is the second case in the literature of cDAPVF causing hemoptysis in an adult.

A 19-year-old man was admitted to our department because of hemoptysis for 10 days that was aggravated for 2 hours before admission. Ten days before admission, he had a cold and coughed up bloody sputum and he denied fever, chest pain, night sweats and dyspnea. The symptom of bloody sputum worsened in the 2 hours before he came to the hospital, and the amount of hemoptysis was approximately 30 mL.

On pulmonary auscultation, moist rales were heard at the left lower part of the lung, but no pathologic cardiac murmur was heard at any valve area. Routine blood tests and coagulation function were all within reference range. CT scan showed consolidation of the basal segment of the left lower lobe. According to the clinical presentation and radiological results, the patient was diagnosed with pneumonia. To exclude bronchial artery diseases, bronchial artery CT angiography was performed, and it showed an abnormal artery arising from the descending thoracic aorta on the left, giving rise to curl vessels in the basal segment of the left lower lobe and draining into the dilated left inferior pulmonary vein (Figure). The final diagnosis of cDAPVF was made.

Congenital descending aorta-pulmonary vein fistula is a rare congenital fistula between the descending aorta and the pulmonary vein that is often diagnosed in infancy. This cDAPVF arises from the thoracic aorta and drains into the left inferior pulmonary vein. The major hemodynamic consequences of cDAPVF include increased pulmonary veins pressure, retrograde perfusion into segments of the lung and the possibility of segmental pulmonary hypertension. The systemic circulation has a higher blood pressure than does the pulmonary circulation, so an increased blood flow through the fistula drains to the left atrium and the fistula also provides a passage for retrograde perfusion of the lung parenchyma, finally causing dilation of the left atrium and elevation of pulmonary venous pressure. Persistently elevated inferior pulmonary venous pressure could result in involved segmental pulmonary hypertension.

The main clinical manifestations of cDAPVF are hemoptysis and heart murmur, but some patients may be asymptomatic. Rupture of dilated small pulmonary venous of the basal segments secondary to increased pulmonary venous pressure likely underlies hemoptysis in our patient. Contrast-enhanced CT scan is an appropriate imaging method to confirm diagnosis. It can demonstrate not only pulmonary parenchymal changes but also its systemic arterial supply and pulmonary venous drainage. The main differential diagnoses include pulmonary sequestration and anomalous systemic arterial supply to normal basal segments of the left lower lobe (Table). Pulmonary sequestration is defined as an area of dysplastic or nonfunctional lung tissue that lacks communication with the tracheobronchial tree, and receives its blood supply from 1 or more anomalous systemic arteries. Pulmonary sequestration is a condition in which the lung parenchyma is supplied by the anomalous systemic artery; however, cDAPVF is a left-to-left shunt with no involvement of lung parenchyma. Besides, pulmonary sequestration consists of abnormal lung tissue, whereas the lung tissue in cDAPVF is normal. Anomalous systemic arterial supply to normal basal segments of the left lower lobe with normal pulmonary parenchyma connection of the lower lobe, which always has no pulmonary arterial supply, is an uncommon congenital anomaly. The characteristics of this anomaly include anomalous systemic artery arising from descending aorta, absence of pulmonary arterial supply and normal pulmonary parenchyma, as well as normal bronchial system in the basal segments. Anomalous systemic arterial supply to normal basal segments of left lower lobe is similar to cDAPVF, but the former has a normal pulmonary capillary flow fed by the anomalous vessels and lacks pulmonary arterial supply, thereby different from cDAPVF.

Congenital descending aorta-pulmonary vein fistula is curable with surgical ligation of the abnormal artery. However, pulmonary sequestration and anomalous systemic arterial supply to normal basal segments of the left lower lobe may cause lung infarction. Treatment of pulmonary sequestration and anomalous systemic arterial supply to normal basal segments of the left lower lobe includes resection of the abnormal lung segment.