Syncope Flashcards
What is the prevalence of syncope?
15%
Define syncope
Transient loss of consciousness and muscle tone resulting from inadequate cerebral perfusion
Define presyncope
Sensation of being about to faint with transient loss of postural tone but no LOC
What is the most common cause of syncope?
Vasovagal episode
List three causes of orthostatic intolerance
- Vasovagal syncope
- Orthostatic hypotension
- Postural orthostatic tachycardia syndrome (POTS)
What patient population is most commonly affected by vasovagal syncope?
- Adolescent girls
- Rare in kids under the age of 10-12
Describe vasovagal syncope
- Prodrome lasting seconds to a minute: dizziness, nausea, pallor, diaphoresis, palpitations, blurred vision, HA, hyperventilation
- Loss of consciousness and muscle tone
- Fall without injury
- Unconsciousness doesn’t last more than one minute
What are common triggers for vasovagal syncope?
- After rising in the morning
- After taking a morning shower
- Prolonged anxiety
- With fright, pain, anxiety, blood drawing, fasting
- Hot and humid conditions, crowded places
- After excersize is stopped abruptly
What is the pathophysiology of vasovagal syncope?
- Not well understood
- Prolonged standing = blood pooling in LE and decreased venous return, decreased stroke volume and BP
- Reduced ventricular filling = less stretch on mechanoreceptors = decreased afferent neural output + decreased arterial pressure = tachycardia and peripheral vasoconstriction
Describe management of vasovagal syncope
- Hydration
- Supine position with feet elevated
- Fludrocortisone (Florinef)
- B blockers
- Pseudoephedrine
What is the normal physiologic response to standing?
- Reflex arterial and venous constriction
- Slight increase in HR
What is the pathogenesis of orthostatis hypotension?
- Normal adrenergic vasoconstriction of arterioles and veins in the upright position is absent or inadequate
- Hypotension without reflex increase in HR
Contrast prodromes of orthostatis hypotension and vasovagal syncope
- Orthostatic hypotension: lightheadedness alone
- Vasovagal syncope: dizziness, nausea, pallor, diaphoresis, palpitations, blurred vision, HA, hyperventilation
What factors can exacerbate orthostatic hypotension?
- Medications
- Dehydration
- Prolonged bed rest
- Prolonged standing
- Low circulating blood volume
- Drugs inerfering with sympathetic response: CCBs, antihypertensives, vasodilators, phenothiazines, diuretics
What is the AHA definition of orthostatic hypotension?
- Persistent fall in systolic/diastolic pressure of more than 20/10mm Hg within 3 mins of assuming the upright position without moving the arms or legs with no increase in HR but without fainting