A silent anomaly: congenital unilateral absence of pulmonary artery incidentally discovered in adulthood, presenting as pulmonary hypertension and chronic respiratory failure—case report

Background: Unilateral absence of the pulmonary artery (UAPA) is a rare congenital anomaly that results from the failure of the sixth aortic arch to connect with the pulmonary trunk during embryogenesis. Left-sided UAPA is often associated with congenital heart diseases, whereas right-sided UAPA is typically isolated and asymptomatic. There is limited literature available on individuals diagnosed with UAPA in mid-adulthood. Therefore, this case report seeks to contribute to the existing knowledge, aiming to enhance understanding of UAPA in this age group and its associated management goals. Case Description: Case 1 involves a 44-year-old man with a history of heavy smoking and chronic obstructive pulmonary disease (COPD), who presented with hypoxia, hemoptysis, and worsening dyspnea. Despite a history of noncompliance with medication, further examinations revealed severe pulmonary arterial hypertension (PAH) due to congenital absence of the right main pulmonary artery (PA) and extensive systemic arterial collateralization. Treatment included bronchodilators, supplemental oxygen, sildenafil, ambrisentan, and spironolactone. However, he ultimately succumbed to right ventricular failure. A previous computed tomography (CT) angiogram had shown absence of the right PA, indicating a congenital condition, but the patient was lost to follow-up after being referred for a lung transplant. Case 2 describes a 46-year-old woman of Ghanaian descent with uncontrolled asthma and a significant history of dyspnea and respiratory distress linked to aspirin allergy. Investigations revealed an absent right PA leading to a hypoplastic right lung with chronic changes, and severe PAH. Treatment with corticosteroids and nebulization led to improvement, but a right heart catheterization confirmed elevated pulmonary pressures and a left-to-right shunt due to collateral circulation. An aortogram showed a large fistulous connection to the hypoplastic lung. A complex intervention involving the placement of coils in the collateral vessels achieved a successful outcome. Conclusions: UAPA in adulthood is a diagnostic and therapeutic challenge due to its rarity, necessitating careful evaluation and individualized treatment approaches.