Isolated unilateral absent pulmonary artery - A case report

Clinical History

A 23-year-old female patient with complaints of chest pain and dyspnoea during exercise for one year, which did not respond well to treatment, was suspected for cardiovascular congenital abnormality and referred to radiology department of French Medical Institute for Mothers and Children for contrast-enhanced chest CT scan.

Imaging Findings

Chest CT scan with IV contrast was performed for the patient. Dilatation of the right atrium was noted (Fig. 1). Dilated pulmonary trunk was seen compared to the ascending aorta in the axial mediastinal window (Fig. 2). MIP and colour LUT images showed absent left pulmonary artery with evidence of abrupt cut-off in proximal part while right pulmonary artery and its branches existed (Fig. 3a-d). Prominent enhanced vessels were noted along the left side of thoracic vertebrae and descending aorta representing collateral vessels (Fig. 4a-c). Volume-rendered images clearly showed absent left pulmonary artery and normal right pulmonary artery and its branches (Fig. 5a-b).

Discussion

Isolated unilateral absent pulmonary artery (IUAPA) is a rare congenital anomaly. The broader category is UAPA which is accompanied by other congenital heart anomalies like tetralogy of Fallot, cardiac septal defects, coarctation of the aorta and sub-valvular aortic stenosis. The prevalence of UAPA is 1/200000 in population with no sex predilection [1]. The anomaly was diagnosed for the first time in 1868 [2]. Failure of migration and rotation of the sixth aortic arch segment results in absence of the pulmonary artery [1]. UAPA is commonly seen in the site of the chest opposite the aortic arch with only 2% occurring in the same site of the aortic arch [3] as it was in our case. The distal branches of the pulmonary artery remain intact by getting blood from collateral vessels of bronchial, internal mammary, subclavian, sub-diaphragmatic, intercostal and even coronary arteries [2-4]. The clinical features of UAPA are chest pain, pulmonary oedema, dyspnoea during exercise, haemoptysis, pleural effusion, recurrent pulmonary infection, bronchiectasis and even death which is usually caused by severe pulmonary haemorrhage, right side heart failure and respiratory failure. Some of the cases are asymptomatic and detected incidentally [3-5]. One of the consequences of UAPA is pulmonary hypertension. Haemoptysis is another complication which can be serious sometimes, due to unusual high pressure in the collateral vessels [6]. The findings in a chest X-ray are asymmetric lung fields with absent or diminished hilar vasculature, shifting of mediastinum towards the affected hemithorax and elevation of the hemidiaphragm in the affected side [1-5]. The definitive diagnosis of UAPA can be made by angiography, chest CT, MRI, echocardiography and nuclear imaging. Ventilation perfusion scan can be done to differentiate the pulmonary hypertension of IUAPA from chronic thromboembolic pulmonary hypertension [1- 7]. Different treatment strategies exist, such as surgical, pharmacological and behavioural management. In recurrent haemoptysis, pulmonary infection and pulmonary hypertension pneumonectomy and surgical revascularisations are done. Selective embolisation of bronchial or non-bronchial systemic arteries is suitable for patients with massive haemoptysis who are not eligible for surgery. Pharmacological treatment is for patients not tolerating the revascularisation surgery or those who don’t improve after surgery [8]. Our patient got medical treatment and advice. In conclusion, UAPA is a rare congenital problem that is usually diagnosed in adolescent and adult population and clinicians should keep in mind the possibility of undiagnosed cases.

Differential Diagnosis List

Final Diagnosis

Isolated unilateral absent pulmonary artery (IUAPA)

URL:	https://www.eurorad.org/case/14791
DOI:	10.1594/EURORAD/CASE.14791
ISSN:	1563-4086