When most of us hear “hypertension,” we immediately think of blood pressure issues all over the body. But people with pulmonary arterial hypertension (PAH) have problems in a very specific area: the blood vessels running from the heart to the lungs.
With that important highway clogged, they can’t get enough oxygen. To compensate, their blood pressure rises. All the extra work makes heart failure a real danger.
What is pulmonary arterial hypertension?
The first sign of pulmonary arterial hypertension is usually shortness of breath while exercising. As time passes, people who once were active find that even short walks can leave them winded and tired. Dizziness and feelings of pressure or even pain in the chest are also common. Because their bodies hold onto fluid, they must be careful to avoid drinking too much water.
“It rarely comes on overnight — it’s usually over the course of several months,” said Kenneth Ausloos, MD, associate director of the Advanced Heart and Lung Disease Center at Baylor University Medical Center, part of Baylor Scott & White Health.
PAH was once thought of as a disease of young women. But with newer tests such as echocardiography to study heart function, physicians now see it in all age groups and populations.
“The most common cause is ‘idiopathic,’ which means we don’t know what the cause is,” said Peter McCullough, MD, vice chief of cardiovascular disease at Baylor University Medical Center and cardiologist on the medical staff at Baylor Scott & White Heart and Vascular Hospital – Dallas.
The second most common causes of PAH are connective tissue diseases, such as scleroderma, which affect about a third of patients.
Specialized pulmonary hypertension treatment centers, like the Advanced Heart and Lung Disease Center at Baylor University Medical Center, have expertise in determining a patient’s specific risk, which affects treatment choices. There are now three FDA-approved classes of treatment for PAH.
“If a patient is in a higher risk group, we may start him out on two agents rather than one agent,” Dr. Ausloos said. “In some cases, we may even use all three.”
All the current PAH treatments are vasodilators — they widen the arteries and veins to allow more blood to pass through. But these help some patients more than others. A 2012 study found that nearly two-thirds of patients with idiopathic PAH survive for at least five years. But less than half of patients with connective tissue disease-associated PAH survive that long.
That statistic has doctors eager to find more treatments.
“The current therapies don’t change the underlying problem,” Dr. McCullough said.
Treatment breakthroughs on the horizon for PAH
A new treatment option being developed by a Dallas-based pharmaceutical company offers fresh hope. It’s called bardoxolone methyl, or BARD, and it was originally developed for diabetic kidney disease. Dr. McCullough has been studying BARD as a treatment for kidney disorders for 10 years.
“But it’s now being explored in pulmonary hypertension, neurological problems and cancer,” he said.
BARD switches on a protein called Nrf2. That boosts the function of the mitochondria, the cellular “powerhouses” that create the energy our cells need to work. BARD also blocks another protein, NF-kB, which causes cell damage and is found at higher levels in patients with PAH.
In a recent study, patients taking BARD for 16 weeks were able to walk more than 120 feet farther over six minutes than they had been at the beginning of the study.
“The six-minute walking distance test is the gold standard set by the FDA for measuring treatment effectiveness in pulmonary arterial hypertension,” Dr. McCullough said.
Dr. McCullough and his team are now studying BARD in a trial called CATALYST. It will enroll up to 200 patients around the world, including at Baylor University Medical Center.
“Our current therapies help open up the blood vessels and improve patient symptoms,” Dr. McCullough said. “But if we can add a drug like this that actually changes the fundamental problem of the disease, that would be very positive.”
This blog post was contributed by Matt Windsor.