Table of Contents
Definition of Hypotension
Factors that decrease the flow of blood through the body typically result in reduced blood pressure.
Idiopathic hypotension (hypotension that exists without apparent cause) often suggests a neurologic cause that reflects damage to the brainstem or hypothalamus.
Stroke that interrupts blood flow to these parts of the brain may be accountable, interfering with the body’s blood pressure regulation mechanisms.
Causes of Hypotension
Hypotension is a frequent side effect of many medications to treat cardiovascular disease, among them diuretics, antihypertensives (drugs to lower blood pressure), and alpha blockers (drugs to lower blood pressure or treat arrhythmia).
Cardiovascular conditions that reduce cardiac output (the heart’s ability to pump an adequate volume of blood to meet the body’s oxygenation needs) are common causes of hypotension. Such conditions include severe dilated cardiomyopathy, advanced heart failure, bradycardia and other arrhythmias that slow the heart, aortic stenosis, and unrecognized heart attack.
Hypotension, notably postural hypotension (a sudden drop in blood pressure upon arising), may be a symptom of Addison’s disease, an autoimmune disorder that destroys the adrenal glands. The adrenal glands produce the key hormones that increase blood pressure, aldosterone, epinephrine, and norepinephrine.
Symptoms and Treatment
The most common symptoms of hypotension are lightheadedness and syncope (fainting), especially when rising from sitting or lying down. The normal pull of gravity causes blood to temporarily pool in the large veins of the legs.
Any lapse between the change of position and the signals that activate the body’s blood pressure regulation mechanisms, results in an inadequate blood supply to the brain that causes loss of consciousness
Syncope following meals, called postprandial syncope, also is common, as the body draws an increased blood volume to the gastrointestinal tract to support the functions of digestion. The diagnostic path typically includes review of medications the person is taking as well as blood tests to measure levels of the adrenal hormones, blood electrolytes, and blood composition.
Treatment depends on the underlying cause. When the cause is medication, changing the dose or switching to a different medication often remedies the hypotension. Neurologic and endocrine causes may require more extensive diagnostic evaluation and comprehensive treatment approaches.
See also ADRENAL INSUFFICIENCY; AUTOIMMUNE DISORDERS; HORMONE; PHEOCHROMOCYTOMA.