Pulmonary hypertension

August 2, 2011

Normally, the pressure in the lung circulation is five times lower than blood pressure in the arteries. Any abnormal elevation in the arterial or venous pulmonary pressures can lead to pulmonary hypertension (elevated pressure in the lung circulation). Pulmonary hypertension is a multifactorial disease causing breathlessness on exertion, fatigue, and hypoxemia (lowered oxygen levels in the blood), and in severe forms is associated with high mortality and need for lung transplant. Because the pulmonary circulation carries blood between the right and the left heart, any disease of the left heart can lead to pulmonary hypertension and consequently any chronic disease of the lung or pulmonary circulation will impose a strain upon and can lead to right-sided heart failure.

Primary pulmonary hypertension (PPH, also called idiopathic) is pulmonary hypertension of unknown cause. It is twofold more common in women than men and fourfold more frequent in blacks. Although the exact mechanism is not known, it has been hypothesized that the disease occurs in patients with a genetic predisposition for an abnormal proliferation of small pulmonary arteriole/capillaries and is triggered by certain environmental factors. Such factors include appetite suppressants, cocaine, and autoimmune connective tissue disorders such as Systemic lupus erythematosus. Women comprise up to 75% of patients who have either taken appetite suppressive drugs or have systemic lupus. Anorectic drugs have been used for more than 30 years to help reduce weight in obese patients. The amphetamine aminorex led to an epidemic of pulmonary hypertension in late 1960s. The most recent ones, fenfluramine and dexfluramine, can cause pulmonary hypertension. These drugs have also been linked to aortic and mitral valvular disease (abnormality in aortic and mitral valves) and have been voluntarily withdrawn from the market.

Connective tissue diseases such as Systemic lupus erythematosus, scleroderma, and phospholipids syndrome are also associated with pulmonary hypertension in women. The treatment of PPH consists of oral or intravenous vasodilators and anticoagulants (meaning blood thinners and warfarin). The oral vasodilators of choice are long-acting formulations of calcium channel blockers (such as nifedipine or diltiazem). However, only about one third of patients respond to this treatment. There are new therapies currently utilized, such as epoprostanol and bosentan.

SEE ALSO: Acute myocardial infarction, Cholesterol, Coronary risk factors, Diabetes, Hormone replacement therapy, Hypertension, Oral contraception, Smoking, Stroke, Systemic lupus erythematosus, Venous thromboembolism

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Category: Cardiovascular Disease