A previously healthy 50-year-old woman comes to the physician because of progressive dyspnea, fatigue, and chest pain during exercise for the last 5 months. She does not smoke. Her maternal uncle had similar symptoms. Cardiac examination shows wide splitting of S2. The second component of S2 is loud and best heard at the 2nd left intercostal space. Further evaluation indicates no evidence of obstructive or interstitial lung disease or venous thromboembolism. Cardiac catheterization results are as follows: Pharmacotherapy blocking the effects of which of the following substances is most likely to benefit this patient?

Question

A previously healthy 50-year-old woman comes to the physician because of progressive dyspnea, fatigue, and chest pain during exercise for the last 5 months. She does not smoke. Her maternal uncle had similar symptoms. Cardiac examination shows wide splitting of S2. The second component of S2 is loud and best heard at the 2nd left intercostal space. Further evaluation indicates no evidence of obstructive or interstitial lung disease or venous thromboembolism.  Cardiac catheterization results are as follows:  Pharmacotherapy blocking the effects of which of the following substances is most likely to benefit this patient?

Quizplus · Accepted Answer

Eductional Objective: Pulmonary arterial hypertension leads to a rise in right ventricular afterload because the RV must work harder to eject blood during systole. Over time, this effect can lead to RV myocardial dysfunction (cor pulmonale). The increased afterload prevents adequate pumping of blood from the RV and delays the closure of the pulmonary valve, resulting in a wide or fixed split S2. Furthermore, the increased diastolic pressure within the pulmonary artery leads to increased velocity of pulmonary valve closure, resulting in a loud P2.
Endothelin receptor antagonists (eg, bosentan, ambrisentan) lower pulmonary arterial pressure and improve dyspnea in patients with pulmonary arterial hypertension.

A Previously Healthy 50-Year-Old Woman Comes to the Physician Because