Definition
Orthostatic hypotension consists of a sudden drop in blood pressure following the sudden transition from a sitting or lying position (stance posture) to an erect one (orthostatism).
In order to be able to speak for all purposes of orthostatic hypotension, the drop in blood pressure must be consistent, greater than 20 mmHg for systolic pressure or 10 mmHg for diastolic blood pressure.
Symptoms
Orthostatic hypotension very often determines a whole series of symptoms, triggered by the reduced flow of blood to the vital organs, particularly to the brain. This can cause unpleasant dizziness and visual difficulties (temporary blindness or blurred vision), feelings of failure, weakness or fatigue, profuse sweating, confusion and headache up to a real syncope (fainting). The increased risk of falls raises, especially in elderly people, 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 also seem to negatively affect the health of the brain.
Orthostatic hypotension is experienced, on at least one occasion, by many people, especially the elderly. These are generally mild episodes that resolve within a few seconds or minutes of standing upright; severe symptoms, which are repeated frequently or last for a long time, deserve to be promptly submitted to medical attention; similar 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 fails to immediately return all the seized blood and to oppose with sufficient effectiveness the blood stagnation; the result is an inevitable reduction in the return of blood to the heart. The reduced blood flow and the resulting drop in blood pressure are immediately picked up by some cellular structures called baroceptors, located near the heart and neck; these organelles trigger a systemic response that brings blood pressure back to normal, therefore based on increasing the constriction of blood vessels, but also on the frequency and cardiac contractility. If something in this compensation mechanism does not work properly, the drop in blood pressure is such as to trigger the symptoms typically associated with orthostatic hypotension; this condition can be consequent to:
- dehydration: if the water losses resulting from fever, vomiting, diarrhea, profuse sweating and strenuous exercise are not reintegrated, there is an impoverishment of the body water, including the liquid fraction of the blood: the plasma decreases its volume, with a significant decrease of blood pressure.
- Diabetes: when it is not adequately treated with appropriate drugs, diabetes leads to the loss of sugar with 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. Furthermore, 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, necrosis of myocardial tissue (infarct) and heart failure, favor the establishment of orthostatic hypotension, because they undermine the heart's ability to pump circulating quantities adequate blood to compensate for the low blood return.
- Degenerative neurological diseases, such as Parkinson's disease, amyloidosis, Shy-Drager syndrome and multisystem 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 muscles of the leg and thigh, together with the valve component of the venous circulation, is fundamental to favor the blood return of the heart against the force of gravity; here then that the maintenance of a static position after standing up, favors the onset of orthostatic hypotension. The presence of varicose veins is also a predisposing factor.
Treatment
Generally, by sitting or lying down after an episode of orthostatic hypotension, symptoms are quickly resolved and normal blood pressure is recovered.
In the most serious cases, in addition to the treatment of the underlying pathology, specific drugs can be useful for the treatment of orthostatic hypotension.
