Exercise and Pulmonary Hypertension (PH)
Kristina Kudelko, MD, Clinical Associate Professor of Pulmonary Medicine, Stanford School of Medicine
Should someone with PH exercise?
It is no surprise that every good doctor advocates a healthy diet and exercise regimen for her patients. An apple (or perhaps a 30-minute jog) a day, after all, keeps the doctor away. However, for patients with pulmonary hypertension, exercise has not always been endorsed.
Why has exercise in PH patients been discouraged?
In fact, until recently, pulmonary hypertension itself has been considered a contraindication to exercise, as too rigorous a regimen can lead to abnormal cardiac rhythms, dangerously low blood pressure, and acute right heart strain.
What happens when someone with PH exercises?
The reason for this is that the compensatory response to exercise is impaired in patients with pulmonary hypertension. Normally, when individuals exercise, blood flow (or cardiac output) increases to the lungs. The lungs respond by “recruiting” an increased number of smaller vessels (or arterioles) in order to accommodate this increase in blood flow and maintain a stable pulmonary arterial pressure and a stable if not decreased pulmonary vascular resistance.
This might make more sense if we are reminded of the relationship between pulmonary vascular resistance and pressure: pulmonary vascular resistance is proportional to pulmonary arterial pressure and inversely proportional to cardiac output. Alternatively, Pulmonary vascular resistance ~ pulmonary arterial pressure / cardiac output.
We know that pulmonary arterial hypertension is a disease of these pulmonary arterioles which become obliterated by an unregulated growth of cells and, in some cases, small blood clots, as well as subjected to pulmonary arterial pressures as high as five times normal. Therefore, when patients with pulmonary arterial hypertension attempt to exercise, they hit an early barrier as their lungs cannot easily recruit healthy arterioles. In light of the relationship above, their pulmonary arterial pressure increases out of proportion to their exercise-induced elevation in cardiac output, resulting in an increased pulmonary vascular resistance with exercise. Over time, this has been shown to lead to progressive shortness of breath on exertion as well as declining six-minute walk distances. And in comparison to control groups, patients with pulmonary hypertension just cannot generate a sufficient cardiac output against this resistance.
Does lack of exercise affect the rest of my body?
What has more recently been elucidated is that skeletal muscles vital to exercise (e.g. the quadriceps of the leg) pay the price. That is, less cardiac output to skeletal muscles leads to muscle atrophy (i.e. wasting away) because less oxygen is delivered to them and because muscles are not used frequently enough to build up muscle strength. Hence the vicious cycle begins.
How do I break the cycle?
What can we do to break this cycle? Intuitively (or counter-intuitively), the answer is: EXERCISE. In 2006, a study was performed in symptomatic pulmonary arterial hypertension patients who were asked to exercise, under the direct supervision of trained rehabilitation professionals, seven days a week for three weeks as an inpatient and continue with a modified 12-week regimen at home. Cycling every day, one-hour walks three times a week, 30-minute dumbbell sessions three times a week, and 30-minute resistance training sessions three times a week comprised the intense inpatient regimen. By the end of the 15 weeks, the exercise group increased their six-minute walk distances by 96 meters (!) compared to a loss of 15 meters in the control group. In comparison, some of the medications used to treat pulmonary arterial hypertension only increase six-minute walk distances by 30 to 40 meters before they are approved for use.
Subsequent studies have supported these findings and added information in other realms like proof of gain of quadriceps muscle mass with exercise and skyrocketing patient-driven scores on quality of life scales at the end of cardiopulmonary rehabilitation programs. Furthermore, none of these studies reported severe adverse outcomes like acute right heart failure or death with exercise.
What type of exercise is best for PH patients? How should I start?
It is critical to stress the importance of exercising under supervision. Trained professionals in cardiopulmonary rehabilitation centers are a vital to starting patients on a safe, individualized exercise program. Each patient is different. For example, some patients require a continuous pump for their medical therapy which must be closely monitored during activity. Some patients have joint abnormalities which interfere with certain exercise options. Some patients present with mild exercise limitations while others become winded at only a few steps.
Rehabilitation specialists know well how to cater to individual patients while providing them with a challenging exercise program at the same time. Moreover, these specialists rely on the specific ‘exercise prescription’ submitted by the pulmonary hypertension team who knows each patient best. Finally, patients with pulmonary arterial hypertension are still at risk for serious events with even less than rigorous exercise; hence, they should be surrounded by medically-trained people who know how to address these events should they occur.
What is the take home message?
Take-home message? Be open to cardiopulmonary rehabilitation if your doctor offers this to you! Exercise is becoming an important adjunct therapy for patients with pulmonary hypertension. Get moving!
- Mereles D et al., “Exercise and respiratory training improve exercise capacity and quality of life in patients with severe chronic pulmonary hypertension,” Circulation 2006, 114:1482-1489.
- de Man FS et al., “Effects of exercise training in patients with idiopathic pulmonary arterial hypertension,” Eur Resp J 2009, 34:669-675.
- Fox BD et al., “Ambulatory rehabilitation improves exercise capacity in patients with pulmonary hypertension,” J Card Fail 2011, 17:196-200.
- Sun X-G et al., “Exercise pathophysiology in patients with primary pulmonary hypertension,” Circulation 2001, 104:429-435.