Pulmonary arterial hypertension (PAH) is a rare but very dangerous condition characterized by a pulmonary arterial pressure >25 mm Hg.
Pulmonary arterial hypertension (PAH) can be idiopathic (IPAH) or associated with a number of predisposing diseases (APAH) that include COPD (Cor pulmonale), left ventricular failure, connective tissue disorders as well as fenfluramine (appetite-suppressant), HIV and sickle cell disease.
Patients with PAH may remain asymptomatic for years. Those that do present with symptoms usually present with exertional dyspnea (60% of cases) that is characterized as being relentlessly progressive in the absence of, or out of proportion to, underlying heart or lung disease. Other symptoms include chest pain which may be pleuritic, low cardiac output symptoms such as syncope (classically exertional or after a warm shower), as well as manifestations of right sided heart failure such as jugular venous distention, abdominal distention, ascites and peripheral edema. In some cases the enlarged pulmonary artery causes compression of the recurrent laryngeal nerve leading to hoarseness of voice.
Cardiac examination reveals a prominent parasternal heave, a loud S2 on auscultation (with paradoxical splitting), as well as a pansystolic murmur due to tricuspid regurgitation that increases with inspiration.
Several investigations may suggest the diagnosis including echocardiography/doppler, ECG and chest radiography. Ultimately, the diagnosis should be confirmed by ventilation/perfusion scan, right heart catheterization and pulmonary angiography.
Patients may require oxygen therapy to treat dyspnea and should avoid vigorous exercise. Dyspnea may also benefit from the use of diuretics.
Vasoreactivity response testing is performed during right heart catheterization using short acting vasodilators such as epoprostenol or adenosine. A fall in pulmonary artery pressure of >10 mmHg is considered a positive response. These patients will benefit from treatment with calcium channel blockers.
Other vasodilators include prostanoids (Epoprostenol , Treprostinil), Guanylate Cyclase Stimulators (Riocigulat), Endothelin receptor antagonists (Sitaxsentan), and phosphodiesterase inhibitors (Sildenafil).
Treatment of secondary or associated PAH should be directed at the cause (COPD, heart disease, thromboembolism, HIV).
Advanced cases may require lung transplantation which cures PAH, but is associated with transplant complications and a median survival of approximately 5 years.
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