Understanding pulmonary arterial hypertension
Although potent combination anti-HIV therapy (commonly called ART or HAART) is good at suppressing the production of HIV by infected cells, it does not cure HIV infection. Chronic HIV infection causes inflammation that is only partially suppressed by ART. Some researchers worry that prolonged inflammation incited by HIV may slowly degrade the health of the body’s organ-systems. This damage caused by chronic inflammation could lead to the intensification of pre-existing health problems or to the onset of new ones. It may, in part, explain the reason for the elevated risk of cardiovascular disease faced by HIV-positive people. Another problem that can occur among HIV-positive people that is probably related to inflammation is pulmonary arterial hypertension (PAH).
In the time before potent combination therapy for HIV became available, researchers noticed that some HIV-positive people developed PAH. Monkeys infected with simian immunodeficiency virus (SIV), which can cause an AIDS-like disease in susceptible animals, can also develop a PAH-like condition. Some researchers theorize that HIV-infected cells of the immune system that circulate within the lungs release chemical signals that cause inflammation in these organs, particularly in the main blood vessels that supply oxygen-rich blood to the heart. Yet, so far most HIV-positive people do not appear to get PAH.
Risks for PAH
Researchers do not know all the causes of PAH but have found that the following factors affect a person’s risk for developing it:
- gender – women are generally at greater risk for PAH than men, the precise reasons for this are not known
- stimulants – use of stimulants such as amphetamine, methamphetamine (crystal meth) and cocaine
- blood clots – people whose blood clots faster than normal
- genes – people whose parents or siblings have PAH
Initially, people with PAH may be symptom free. However, over time, PAH causes abnormalities in the arteries of the lungs, and so the following symptoms can develop:
- shortness of breath
- lack of energy
- chest pain
- swelling in the lower legs
According to surveys in the U.S., historically research suggests that less than 1% of HIV-positive people develop PAH. However, surveys in Western Europe have found greater rates of PAH among people with HIV. The reasons for this difference are not clear.
As part of the medical assessment of patients with potential PAH, a range of tests and procedures can be performed. Initially non-invasive tests may be used, such as an echocardiogram (also known as Doppler echocardiography). Although cardiograms may not yield precise measures of blood pressure within the lungs’ arteries, some doctors find them a useful first step before moving on to more invasive procedures.
As part of recovery from symptoms of PAH, doctors may prescribe gentle exercise, such as walking. Changes to the diet can also be helpful, such as lowering the intake of sodium. Treatment options for PAH can include the following:
- bosentan (Tracleer)
- ambrisentan (Volibris)
- sildenafil (Revatio)
- tadalafil (Adcirca)
Note that the last two drugs listed above have different brand names and doses when used for the treatment of erectile dysfunction.
In some cases, doctors may recommend heart surgery to maintain a person’s quality of life and stabilize the course of PAH until a heart or lung transplant can be performed.
McLaughlin VV, Davis M, Cornwell W. Pulmonary arterial hypertension. Current Problems in Cardiology. 2011;36:461-517.