Orthostatic hypotension

Definition

Orthostatic hypotension is a sharp drop in blood pressure following the sudden transition from sitting or lying (supine) to standing (standing).

In order to be able to speak in all respects of orthostatic hypotension, the blood pressure drop must be consistent, greater than 20 mmHg for systolic pressure or 10 mmHg for diastolic pressure.

Symptoms

Orthostatic hypotension very often determines a whole series of symptoms, triggered by the reduced blood supply to vital organs, especially to the brain. Unpleasant dizziness and visual difficulties (temporary blindness or blurred vision), feelings of faintness, weakness may arise. o fatigue, profuse sweating, confusion and headache up to a real syncope (fainting). The increased risk of falls raises, especially in the elderly, the susceptibility to osteoporotic fractures of traumatic origin; at the same time, the reduced blood return to the heart increases the risk of suffering a heart attack, while repeated episodes seem to negatively affect brain health as well.

Orthostatic hypotension is experienced, on at least one occasion, by many people, especially the elderly. These are generally mild episodes that resolve within seconds or minutes of standing upright; severe symptoms, which recur frequently or persist for a long time, deserve to be promptly submitted to medical attention; analogous speech for a single and isolated episode of fainting.

Causes

When standing up from a lying position, the force of gravity tends to draw blood into the lower limbs; the venous system of the legs is unable to immediately return all the blood seized and to oppose blood stagnation sufficiently effectively; the result is an "inevitable reduction in the return of blood to the heart. The reduced blood flow and the resulting drop in pressure are immediately picked up by some cellular structures called baroreceptors, located near the heart and neck; these organelles trigger a systemic response able to bring blood pressure back to normal, therefore based on the increase in the constriction of blood vessels, but also in the heart rate and contractility. If something in this compensation mechanism does not work properly, the pressure drop is such as to trigger the symptoms typically associated with orthostatic hypotension; this condition may be the result of:

dehydration: if the water losses resulting from fever, vomiting, diarrhea, profuse sweating and strenuous exercise are not replenished, there is an impoverishment of body water, including the liquid fraction of the blood: the plasma decreases its volume, with a significant decrease blood pressure.
Diabetes: when it is not adequately treated with appropriate drugs, diabetes leads to the loss of sugar in the urine; for osmotic reasons this loss is associated with the excretion of large quantities of water. The conspicuous and frequent urination that results is accompanied by dehydration and an inevitable drop in blood pressure. In addition, after many years of illness, diabetes tends to damage the nerves responsible for transmitting nerve signals, including those that help regulate blood pressure.
Heart problems: some heart diseases, such as pathological bradycardia, valve problems, myocardial tissue necrosis (infarction) and heart failure, favor the onset of orthostatic hypotension, because they undermine the heart's ability to pump quantities of adequate blood to compensate for the low blood return.
Degenerative neurological diseases, such as Parkinson's disease, amyloidosis, Shy-Drager syndrome and multiple system atrophy, can damage the blood pressure regulation system.
Hypotensive drugs, antidepressant drugs (MAO-inhibitors, tricyclics), diuretics, anemia (the blood is less viscous) and alcoholism, can favor the onset of orthostatic hypotension.
Static maintenance of the upright position: the contraction of the leg and thigh muscles, together with the valvular component of the venous circulation, is essential to favor the blood return of the heart against the force of gravity; therefore, maintaining a static position after standing up favors the onset of orthostatic hypotension. The presence of varicose veins is also a predisposing factor.

Treatment

Typically, sitting or lying down after an episode of orthostatic hypotension, there is a rapid resolution of symptoms and a return to normal blood pressure.

In severe cases, in addition to treating the underlying pathology, specific drugs for the treatment of orthostatic hypotension may be useful.