Syncope – The Results From Brain Hypoperfusion

Syncope is a transient loss of consciousness and postura tone that a manifestation of hypotension due to cardiac cause ( asystole, third-degree heart block, tachyarrhytmias, outflow obstruction,myocardial infarction) ,low intravascular volume (dehydration,blood loss, addison’s disease), or excessive vasodilation. Syncope results from brain hypoperfusion.

Patients often report visual symptoms such as blurred and graying out before syncope. Patients also feel light-headedness and appear pale or is sweating.

Neurogenic Syncope

  • Acute hemodynamic reaction.
  • Produced by a sudden change in the activity of the autonomic nervous system.
  • Involves a reflex triggered by excessive afferent discharges from arterial (including cardiac or great vessel) or visceral mechanoreceptors.

Afferent impulses via the vagus nerve lead to cardioinhibition and vasodepression, resulting in hypotension and bradycardia. Autonomic failure (an inability to activate efferent sympathetic fibers appopriately, particularly on assumption of the upright posture) usually leads to orthostatic hypotension and also syncope.

Light- headedness is usually complained by patients. Patient have presyncopal symptoms such as weakness, fatigue, cognitive slowing, headache, neck pain, or buckling of the legs. These presyncopal symptoms in response to a sudden change in posture or prolonged standing.

A history and medical and neurologic examinations are warranted in evaluating these patients.

It is important to recognize the potential contribution of drugs ( such as diuretics, antihypertensives, vasodilators, an antidepressants) in managing patients with symptomatic orthostatic hypotension or syncope. Patiens should be advised to raise the head of the bed and move gradually from the supine to standing position. Raising the head of the bed will reduced nocturnal diuresis.  Midodrine and fludrocortisone can be used. To treat neurogenic syncope, you can use beta blockers- suppressing overactive cardiac mechanoreceptors. (by the doctor – rendsan)

Source: Syncope, Results From Brain Hypoperfusion @ HealthyCase
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