Case Study Reveals Use of Bosentan Effective in Treating PH Secondary to Unilateral Absence of a Pulmonary Artery

In a case study published in the International Journal of Cardiology, a team of researchers from China reported the case of a 23-year-old woman with the absence of a right pulmonary artery and patent ductus arterioles who developed severe pulmonary hypertension. The researchers found that the use of bosentan after device closure of the patient’s ductus arterioles was able to decrease pulmonary hypertension pressure. Bosentan, also known by its brand name Tracleer, is a dual endothelin receptor antagonist licensed by Actelion Pharmaceuticals for the management of PAH.

Unilateral absence of a pulmonary artery is a rare congenital anomaly caused by the failure of the sixth aortic arch to connect with the pulmonary trunk during embryologic development, and is often associated with other cardiovascular abnormalities such as tetralogy of Fallot, septal defects, right aortic arch, and persistence of ductus arteriosus, and usually discovered in the pediatric age.

The condition is often incidentally identified in adult patients complaining of recurrent episodes of respiratory infections with or without exertional dyspnea and always complicated with hemoptysis, recurrent pulmonary infections or pulmonary hypertension.

In the study titled “Bosentan in pulmonary hypertension secondary to unilateral absence of a pulmonary artery,” Yuan Feng in the Department of Cardiovascular Surgery at West China Hospital and fellow researchers published a case report of a 23-year-old who was admitted to the hospital with exertional dyspnea and limited exercise tolerance complaints.

The patient was categorized as pink at rest and cyanotic when exercising. Physical examination revealed a harsh S2 sound and a 2/6 systolic murmur at the left upper sternal border, SpO₂ was 85% at rest.

Transthoracic echocardiography showed a 5-mm PDA with bidirectional low shunting, absence of right pulmonary artery and mild tricuspid regurgitation, so her systolic PA pressure was estimated as 60 mm Hg by Doppler echocardiography.

Cardiac catheterization was performed to identify the diagnosis and the patient was discharged on bosentan 62.5 mg bid for the next four weeks and 125 mg bid for the next half a year.

After six-months follow-up, results from the transthoracic echocardiography showed that the pulmonary artery hypertension reduced from 60 mm Hg to 24 mm Hg and that the patient was asymptomatic.

Current management in pulmonary hypertension includes a long-term vasodilator therapy that regulates endothelial function and improves survival. Calcium channel blockers, prostacyclin, and bosentan have been reported to be used by physicians. In this specific case, the researchers concluded that during the six-month follow-up, Bosentan had favorable effects on the patient’s pulmonary hypertension and exercise tolerance. The case study could serve as a future guide for other patients diagnosed with pulmonary hypertension secondary to unilateral absence of a pulmonary artery.