Is the circulatory system affected in ALS?

ALS primarily affects the motor nervous system and does not involve the heart muscle or the vascular system. Based on current knowledge, the muscles within the arteries and veins are not affected.

Despite this general exclusion of the cardiac and vascular muscles, the circulatory system may nevertheless be affected as ALS progresses. Such involvement has been described in a small number of patients who have had the disease for a very long time—usually several years—and are on long-term mechanical ventilation. Circulatory dysregulation has been described in patients who are treated with invasive ventilation and have experienced a prolongation of life beyond the “natural course of the disease.” These manifest as “blood pressure crises,” in which blood pressure may rise or fall without any apparent external factors (particularly without physical exertion, such as during physical therapy).

Like cardiac arrhythmias, this disorder of blood pressure regulation is attributable to involvement of the autonomic nervous system. The autonomic nervous system is responsible for regulating cardiac and circulatory activity, as well as various functions of the gastrointestinal system and other internal organs. Contrary to the original assumption that ALS was limited to the motor nervous system, there is a growing body of evidence that the autonomic nervous system may also be affected in the advanced stages of ALS. In patients on long-term ventilation (most often invasive ventilation), circulatory dysregulation can be a life-limiting symptom.