The term ‘syncope’ refeers to sudden loss of consciousness due to reduced
cerebral perfusion. Syncope the medical term for fainting or passing out, is
precisely defined as a transient loss of consciousness
and postural tone, characterized by rapid onset, short duration, and
spontaneous recovery, due to global cerebral hypoperfusion (low blood flow to
the brain) that most often results from hypotension (low blood pressure). This
definition of syncope differs from others by including the cause of
unconsciousness, i.e. transient global cerebral hypoperfusion. Without that
addition, the definition of syncope would include disorders such as epileptic
seizures, concussion or cerebrovascular accident and syncope is distinguished
from coma, which can include persistent states of unconsciousness. This
confusion still occurs in some literature.
‘Presyncope’ refers to light headedness where the
individual thinks he or she may blackout. Presyncope is a state consisting of
lightheadedness, muscular weakness, and feeling faint (as opposed to a syncope,
which is actually fainting). Pre-syncope is most often cardiovascular in
etiology. In many patients, lightheadedness is a symptom of orthostatic
hypotension. Orthostatic hypotension occurs when blood pressure drops
significantly when the patient stands from a supine or sitting position. If
loss of consciousness occurs in this situation, it is termed syncope.
1. Arrhythmia:
• Profound bradycardia.
• Malignant ventricular tachyarrhythmias.
2. Structural heart disease:
• Severe aortic stenosis.
• Hypertenison obstructive cardiomyopathy.
3. Hypertensitive carotid sinus syndrome.
4. Vasovagal: Prolonged standing, excessive heat ,large meal.
5. Postural hypotension:
• Relative hypotension: Excess diuretic therapy.
• Sympathetic degeneration: Diabetes, Parkinson’s disease.
• Drug therapy: vasodilators, antidepressants.
6. Situational syncope:
• Cough syncope.
• Micturition syncope.
Clinical
test (Presyncope): The tilt table test is an
evaluative clinical test to help identify presyncope or syncope. A tilt angle
of 60 and 70 degrees is optimal and maintains a high degree of specificity. A
positive sign with the tilt table test must be taken in context of patient
history, with consideration of pertinent clinical findings before coming to a
conclusion.
Management
(Syncope): Recommended acute treatment of
vasovagal and orthostatic (hypotension) syncope involves returning blood to the
brain by positioning the person on the ground, with legs slightly elevated or
leaning forward and the head between the knees for at least 10–15 minutes,
preferably in a cool and quiet place. For individuals who have problems with
chronic fainting spells, therapy should focus on recognizing the triggers and
learning techniques to keep from fainting. At the appearance of warning signs
such as lightheadedness, nausea, or cold and clammy skin, counter-pressure
maneuvers that involve gripping fingers into a fist, tensing the arms, and
crossing the legs or squeezing the thighs together can be used to ward off a
fainting spell. After the symptoms have passed, sleep is recommended. If
fainting spells occur often without a triggering event, syncope may be a sign
of an underlying heart disease. In case syncope is caused by cardiac disease,
the treatment is much more sophisticated than that of vasovagal syncope and may
involve pacemakers and implantable cardioverter-defibrillators depending on the
precise cardiac cause.
Reference:
1. Davidson’s Principle and Practice of Medicine, 21st edition.
2. Wikipedia the free encyclopedia.
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