Patients with Pulmonary Arterial Hypertension for Muscle Metabolism

Pulmonary Arterial Hypertension has gone from a disease that causes rapid death to a more chronic condition. Yet, improved survival is associated with major challenges for clinicians as most patients remain with poor quality of life and limited exercise capacity. The effects of exercise training on exercise capacity have been largely evaluated and showed an improvement in 6-minutes walking distance (6MWD), peak V'O2. It is also known that exercise program improves quality of life. Maximal volitional and nonvolitional strength of the quadriceps are reduced in patients with Pulmonary Arterial Hypertension and correlated to exercise capacity. Moreover, on the cellular level, alterations are observed in both the respiratory as well as the peripheral muscles. Muscle fiber size has been reported to be decreased in some studies or conversely unaltered in human and animal models. Reduction in type I fibers and a more anaerobic energy metabolism has also been reported, but not in all studies. Likewise, a loss in capillary density in quadriceps of patients with Pulmonary Arterial Hypertension and rats has been reported, but could not be confirmed in other studies. While the impact of exercise training on clinical outcomes such as exercise capacity or quality of life is well known, this data highlight the fact that the underlying causes of peripheral muscle weakness as well as the mechanisms underlying the clinical improvements observed with exercise programs are not completely understood. Improvement of muscle cell metabolism in part via the enhancement of oxidative cellular metabolism and decrease in intracellular lipid accumulation may play a role in improving muscle function and exercise capacity. In this study, we intend to evaluate the impact of a 12 weeks home-based rehabilitation program on peripheral muscle function and metabolism, focusing on lipid infiltration, oxidative metabolism and epigenetic factors that can be involved in metabolic syndrome, in patients with Pulmonary Arterial Hypertension.