Mechanisms of Circulatory Abnormalities and Fatigue in Patients with Cardiovascular Diseases

Premature fatigue, a hallmark of individuals with cardiovascular diseases such as heart failure or hypertension, substantially impairs the patients' ability to effectively execute tasks of daily living. Although researchers long believed that patients' abnormal circulatory response to physical activity contributed to this premature fatigue, they did not fully understand the mechanism(s)underlying the circulatory abnormalities. Markus Amann, PhD, and colleagues recently discovered that both heart failure and hypertension impair an important neurocirculatory control mechanism in humans-specifically, a reflex loop mediated by neural feedback from muscles to the central nervous system. This impairment results in excessive sympathetic nervous system activity, and largely accounts for the circulatory abnormalities observed during physical activities. In additional experiments, Amann's group demonstrated that the mechanism underlying the impaired circulatory control also accounts for the premature fatigue and limited ability to execute tasks of daily living in patients with cardiovascular diseases.