Unilateral absence of the pulmonary artery (UAPA) is a rare congenital disorder with variable clinical presentation. We report a case of right pulmonary artery agenesis discovered in an adult patient presenting with uncontrolled asthma secondary to recurrent bronchopulmonary infections.
A 53-year-old non-smoker woman was referred to pulmonary clinic because of uncontrolled asthma and frequent respiratory infections. She also described symptoms consistent with gastroesophageal reflux disease (GERD) and rhinitis. Her past medical history included hypertension.At the initial evaluation, the patient was in no acute distress, afebrile and her vital signs were stable. Her physical examination revealed decreased breath sounds with rhonchi in the right lower lung zone. There was no edema, cyanosis or clubbing. Laboratory data was significant for mild anemia. An allergy skin test was positive for dust mite, cats and multiple grasses. Inhaled corticosteroids and long acting beta-agonists were added as well as proton pump inhibitors, nasal steroids and anti-histamines. On subsequent visits, the patient reported improvement in her GERD and rhinitis symptoms but her asthma control was still not optimal.The pulmonary function test showed FEV1/FVC ratio of 83, FEV1 of 1.43L (65 % of predicted), FVC of 1.72L (64% of predicted), total lung capacity (TLC) of 67 % of predicted and a diffusion capacity for carbon monoxide (DLCO) of 75 % of predicted. Plain chest radiograph showed a loss of volume of the right lung, an increased density in the right lower lung zone with ipsilateral displacement of the mediastinum. A contrast-enhanced computed tomography of the thorax confirmed the radiograph findings and revealed absence of the right pulmonary artery. The patient refused further invasive workup. Her symptoms improved after a course of oral antibiotics and after optimizing her asthma therapy.
Congenital UAPA is a rare anomaly that may occur in isolation but most frequently is accompanied by cardiovascular malformations. The prevalence of isolated UAPA is estimated to be around 1:200,000 individuals.The main embryologic defect is an involution of the proximal 6th aortic arch of the affected side leading to an absence of the proximal pulmonary artery.UAPA is twice more common on the right side, however left-sided agenesis is frequently associated with life-threatening cardiovascular malformations warranting early diagnosis and surgical repair. Patients with isolated right pulmonary artery agenesis survive into adulthood with minimal or no symptoms. Majority of patients are identified incidentally. Symptoms can be unmasked by factors such as pregnancy or high altitude. Recurrent pulmonary infections, decreased exercise tolerance, shortness of breath on exertion and hemoptysis are common manifestations. Pulmonary hypertension is present in 20- 44 % of patients. Typical chest radiographic findings are mediastinal displacement, hemidiaphragm elevation with volume loss of the affected lung, absent hilar shadow and hyperinflation of the contralateral lung. Multiple conditions like Swyer-James-MacLeod’s syndrome, compensatory emphysema and pulmonary thromboembolic disease can have similar radiographic appearance. Contrast-enhanced computed tomography of the thorax usually confirm the absence of the affected pulmonary artery. Echocardiography can establish the diagnosis and exclude any cardiac or major vessels abnormalities. Angiography remains the gold standard for the diagnosis of pulmonary artery agenesis, it is rarely performed unless embolization is indicated for massive hemoptysis. The treatment of UAPA in adults depends upon the clinical presentation. Revascularization of the absent artery is recommended when pulmonary hypertension is present. Pneumonectomy or lobectomy for recurrent hemoptysis or intractable pulmonary infections can be performed.
Clinicians should be aware of the possibility of undiagnosed cases of UAPA presenting with recurrent respiratory infections. A chest radiograph is usually the initial investigation that suggests the diagnosis which can be confirmed by CT scanning. Angiography is reserved for patients requiring embolization or revascularization surgery.
Hafez Hayek, No Financial Disclosure Information; No Product/Research Disclosure Information