Unilateral Absence of a Pulmonary Artery : A Rare Disorder With Variable Presentation

Abstract

Unilateral absence of a pulmonary artery (UAPA) is a rare condition with an estimated prevalence of 1 in 200,000 young adults. Most commonly, UAPA occurs in conjunction with cardiovascular abnormalities such as tetralogy of Fallot or cardiac septal defects, but it can also occur in an isolated manner. Patients with isolated UAPA can remain asymptomatic into late adulthood but usually report symptoms such as dyspnea or chest pain or suffer from hemoptysis or recurrent infections. Diagnosis can be difficult due to the rarity of the condition and its nonspecific presentation. We present a case of a 60-year-old female who presented with history of chronic cough and was found to have UAPA. Typical findings on CT were discussed. The exact embryologic cause of UAPA is a matter of debate and is likely different in left-vs. right-sided UAPA. In both cases, however, altered development of a sixth aortic arch segment is thought to result in a ductal origin to a pulmonary artery that leads to the proximal interruption of that vessel when the ductal tissue regresses at the time of birth. (4) Distal intrapulmonary branches of the affected artery usually remain intact and can be supplied by collateral vessels from bronchial, intercostal, internal mammary, subdiaphragmatic, subclavian, or even coronary arteries. (5,6) Patients with isolated UAPA can present in a variety of ways. A 2002 review of 108 cases of UAPA revealed a median age of presentation of 14 years. (3) The combination of chest pain, pleural effusion, and recurrent infections was present in 37% of patients, while dyspnea or exercise intolerance was present in 40% of patients. Other, Competing Interest: None. Submission 21-04-2015, Peer Review 22-04-2015, Acceptance 31-10-2015, Published 12-11-2015 Pulmonary hypertension was found in 44% of patients that were tested for the disorder. HOW TO CITE THIS ARTICLE: Financial orHemoptysis occurred in about 20% of patients, and high-altitude pulmonary edema was seen in approximately 10% of patients. (3) Seven deaths were noted in the case series and included mortality from massive pulmonary hemorrhage, right heart failure, respiratory failure, pulmonary hypertension, and high-altitude pulmonary edema. Only 14 of 108 patients with isolated UAPA were asymptomatic at the time of their diagnosis and throughout variable follow-up. (3) At the time of our patient's presentation, he reported dyspnea at rest and exercise intolerance. UAPA could definitely be a cause of his dyspnea, and it should be noted that his left lung received 32% of total ventilation on his ventilation perfusion scan but no detectable perfusion, resulting in a large amount of dead space.Pulmonary hypertension could also be a cause for the patient's dyspnea, and indeed, the patient's main pulmonary artery was enlarged, measuring 3.7 cm on his CT pulmonary angiogram (Figure2). However, that study showed no signs of secondary right heart strain. An echocardiogram was ordered but not performed before the patient was lost to follow-up. Other possible c...