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Orthostatic hypotension, also known as postural hypotension, [2] is a medical condition wherein a person's blood pressure drops when they are standing up (orthostasis) or sitting down. Primary orthostatic hypotension is also often referred to as neurogenic orthostatic hypotension. [ 3 ]
Orthostatic intolerance (OI) is the development of symptoms when standing upright that are relieved when reclining. [1] There are many types of orthostatic intolerance. OI can be a subcategory of dysautonomia, a disorder of the autonomic nervous system [2] occurring when an individual stands up. [3]
Orthostatic syncope refers to syncope resulting from a postural decrease in blood pressure, termed orthostatic hypotension. [1]Orthostatic hypotension occurs when there is a persistent reduction in blood pressure of at least 20mmHg systolic or 10mmHg diastolic within three minutes of standing or being upright to 60 degrees on the head-up tilt table.
The ability of baroreflex activation therapy to reduce sympathetic nerve activity suggests a potential in the treatment of chronic heart failure, because in this condition there is often intense sympathetic activation and patients with such sympathetic activation show a markedly increased risk of fatal arrhythmias and death. [citation needed]
This postural hypotension usually happens shortly after the first dose is absorbed into the blood and can result in syncope (fainting). Syncope occurs in approximately 1% of patients given an initial dose of 2 mg prazosin or greater. This adverse effect is self-limiting and in most cases does not recur after the initial period of therapy or ...
Sympathetic failure manifests itself as orthostatic hypotension and anhidrosis. Orthostatic symptoms, which include lightheadedness, dizziness, or syncope upon standing and loss of postural reflex tachycardia, occur in 78% of patients. [1] Dry eyes and mouth are symptoms of parasympathetic failure caused by secretomotor dysfunction.
Baroreflex and autonomic pathways normally ensure that blood pressure is maintained despite various stimuli, including postural change. The precise mechanism of orthostatic hypertension remains unclear, but alpha-adrenergic activity may be the predominant pathophysiologic mechanism of orthostatic hypertension in elderly hypertensive patients. [5]
This characterization may better define the group of IST patients who are most symptomatic and/or likely to seek medical attention, as opposed to the entire cohort of Inappropriate sinus tachycardia patients. [19] In IST, the most common comorbidities are psychiatric, including a history of depression in 25.6% as well as anxiety in 24.6%.