Cardiovascular system

The cardiovascular system, also called the circulatory system or the vascular system, is an organ system that permits blood to circulate and transport nutrients (such as amino acids and electrolytes), oxygen, carbon dioxide, hormones, and blood cells to and from the cells in the body to provide nourishment and help in fighting diseases, stabilize temperature and pH, and maintain homeostasis. It also includes includes the lymphatic system, which circulates lymph.

Autonomic nervous system dysfunction resulting in orthostatic intolerance (e.g., postural orthostatic tachycardia and orthostatic hypotension), low blood volume, preload failure and other circulatory issues are all thought to contribute to the symptoms of ME.

ME/CFS
Numerous cardiac abnormalities have been documented in Myalgic Encephalomyelitis and Chronic Fatigue Syndrome patients.

These include smaller than normal left ventricle of the heart and low cardiac output.

A 2016 study in the Netherlands was the first to use contrast-enhanced cardiac magnetic resonance (CMR) imaging in assessing cardiac involvement in women who have CFS. Twelve women were recruited from a specialised CFS centre who had a diagnosis of CFS based on the Fukuda criteria. Thirty-six age- and gender-matched controls were also included. The conclusions were that in patients with CFS, cardiac magnetic resonance demonstrated lower left ventricle dimensions and a mildly reduced left ventricle function. Heart wall motion abnormalities and the presence of myocardial fibrosis were observed in some CFS patients.

Reduced cardiac volumes have been associated with blood volume, but not length of disease.

A study found that blood volume is a strong physiological correlate of peak oxygen consumption in patients with CFS.

Orthostatic intolerance is also common.

CFS patients have several risk factors for heart disease. The mean age of death from heart failure of CFS patients is 58.7 years as compared to 83.1 years for the general population.

Notable studies

 * 2007, Usefulness of an abnormal cardiovascular response during low-grade head-up tilt-test for discriminating adolescents with chronic fatigue from healthy controls. (Abstract)
 * 2016, Chronic fatigue syndrome in women assessed with combined cardiac magnetic resonance imaging
 * 2016, The Blood Volume Paradox in ME/CFS and POTS
 * 2016, Reduced cardiac volumes in chronic fatigue syndrome associate with plasma volume but not length of disease: a cohort study

Learn more

 * 2016, "Chronic Fatigue Syndrome: the Small Heart Disease", Health Rising
 * 2016, "Getting to the heart of chronic fatigue syndrome", Science Daily