Summary
Highlights
Pulmonary Arterial Hypertension (PAH) is a rare disorder causing high blood pressure in the pulmonary arteries, which carry blood from the right side of the heart to the lungs. This leads to blood backing up into the right side of the heart, eventually causing right-sided heart failure. It commonly affects middle-aged biological females.
Initial PAH symptoms include difficulty breathing, fatigue, weakness, chest pain, dizziness, and syncope. As the disease progresses, complications like hemoptysis (coughing up blood) and hoarseness due to nerve compression may appear. Untreated, it leads to right-sided heart failure with fluid collection (edema, ascites), liver enlargement, raised jugular venous pressure, and cyanosis in late stages.
PAH is often idiopathic (unknown cause) but can be heritable due to gene mutations like BMPR2, leading to excessive smooth muscle cell proliferation in blood vessels. Other causes include connective tissue disorders (e.g., scleroderma), congenital heart disease with left-to-right shunts, portal hypertension, and risk factors like stimulant drug use (cocaine, amphetamines), HIV infections, and schistosomiasis.
Regardless of the cause, PAH involves vasoconstriction and thickening of pulmonary arterial walls, increasing blood flow resistance. This burdens the right heart, leading to right heart enlargement and eventually core pulmonale or right-sided heart failure.
PAH is a diagnosis of exclusion. Initial steps involve a chest X-ray (showing enlarged pulmonary arteries) or an echocardiogram (revealing increased pulmonary arterial pressure and enlarged right ventricle). Tests to rule out underlying causes include spirometry, ventilation-perfusion scans, and autoantibody testing. Confirmation is done via right heart catheterization to measure lung blood vessel pressures.
PAH management includes supportive therapies like diuretics for edema, supplemental oxygen, and anticoagulants (e.g., warfarin) to prevent clots. Specific treatments involve medications that dilate blood vessels by targeting the prostacyclin pathway (epiprostanol, treprostinil, iloprost, selexipag), the endothelin pathway (ambrisentan, bosentan, macitentan), and the nitric oxide pathway (sildenafil, tadalafil, riociguat). Advanced, irreversible cases may require a double lung transplant.