Pulmonary hypertension can be associated with a variety of conditions (secondary pulmonary hypertension) or it may occur without an identifiable underlying cause (Idiopathic, or unexplained pulmonary arterial hypertension, IPAH). Secondary pulmonary hypertension can result from lung disease, heart disease, low oxygen in the blood (hypoxia) and obstruction of the pulmonary vessels (from clots, foreign body, parasites and certain blood disorders). The term pulmonary arterial hypertension (PAH) refers to the disease arising from the pulmonary arteries themselves, while pulmonary hypertension simply means the pressure is high due to influences of other diseases on the pulmonary arteries. Some conditions may be associated with PAH including cirrhosis, HIV/AIDS, connective tissue diseases, sickle cell anemia, and certain toxins such as phenfluramine (found in some diet pills).
Idiopathic Pulmonary Arterial Hypertension (IPAH) is a rare condition, with an estimated incidence of approximately 1 in every million patients per year, although it appears to be becoming more frequently detected by simple noninvasive means, such as echocardiographic examination. The illness most often occurs in young adults and is more common in women. There is a familial variant of PAH that is genetically transferred from generation to generation in rare cases.
Symptoms of PAH:
The most common symptoms of PAH are tiredness and shortness of breath with exertion. Fainting spells, dizziness, ankle or leg swelling, racing pulse and chest pressure or pain are also typical symptoms. PAH is rarely picked up in a routine medical examination. Even in its later stages, the signs of the disease can be confused with other conditions affecting the heart and lungs. IPAH remains a diagnosis of exclusion. This means that it is diagnosed only after the doctor finds pulmonary hypertension and cannot find other reasons to explain its presence. The evaluation of patients with pulmonary hypertension is involved and should include a right heart catheterization in most patients to directly measure the pressures and confirm the diagnosis.
Treatment of IPAH and PAH:
The course of IPAH is often one of steady deterioration and reduced life expectancy. The untreated patients have a probability of survival of 68% at one year, 48% at three years, and 34 % at five years. Treatment of PAH varies according to the stage of the disease and the degree of impairment in one's exertional capacity. At present, a small portion of patients, about 7-10%, can be treated with oral calcium channel blockers, which are relatively inexpensive and well-tolerated. By relaxing the smooth muscle in the blood vessels, these calcium channel blockers improve the ability of the heart to pump blood. Prostacyclin in the form of prostaglandin I2, is normally produced in the cells of the body and dilates the blood vessels. It is manufactured as a drug (epoprostenol and treprostinil), which can be given as a continuous intravenous or subcutaneous infusion by a battery powered pump. This requires placement of a catheter in one of the central veins. It has been shown to improve survival and exercise tolerance of these patients. These continuous infusion therapies are usually reserved for those with the most severe impairment in exertional capacity.
There are also three oral medications available for PAH (sildenafil, bosentan, and ambrisentan) which can be used in those with moderate to severe impairments in exertional capacity. These are typically well tolerated. Sildenafil should not be taken along with nitrates such as nitroglycerin. Bosentan and ambrisentan require that monthly liver function tests be checked as they have risk of causing damage to the liver. An inhaled prostacylin, called iloprost, can be used in patients with moderate disease. Other therapies such as anticoagulation with warfarin (since small micro-clots form in the pulmonary blood vessels in PAH), diuretics (to help with excess fluid), and digoxin (to help the right heart pump better) are often employed as well.
Heart-lung transplantation or lung transplantation alone is an option for severely affected patients who are not doing well despite aggressive medical therapy. To learn more about transplants at UNC see our Transplantation pages.
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