Syncope and collapse Flashcards
Syncope definition:
Transient, self-limiting loss of consciousness with an inability to maintain postural tone
It has a relatively rapid onset with variable warning symptoms and is followed by spontaneous recovery
Pre-syncope:
Light-headedness without loss of consciousness
Drop attack:
Loss of posture without loss of consciousness
Coma:
Loss of consciousness without spontaneous recovery
Collapse:
Sudden, and often unannounced, loss of postural tone (going weak), which is often, but not necessarily always, accompanied by loss of consciousness
3 categories of Syncope:
Reflex/neural mediated
Orthostatic hypotnesion
Cardiac causes
Reflex/neural mediated causes of syncope:
- Vasovagal syncope
- Situational syncope
- Carotid sinus syncope
Vasovagal syncope:
Most ocmmon typw of syncope
Caused by a sudden drop in BP and a reduction in blood flow to the brain
Caused by vasodilation, bradycardia and/or increased PNS activity
Orthostatic vasovagal syncope
Emotional vasovagal syncope due to fear, phobia and pain
Situational syncope:
Loss of consciousness after defecation, swallowing, micturation and/or coughing
Caused by abnormal autonomic control - cardioinhibitory response, vasodepressor response, both
Carotid sinus syndrome:
Carotid baroreceptors react too strongly to detecting increased pressure -> leadds to an excessive drop in BP
I.e. when someone ties a tie too tight - glossopharyngeal nerve is compressed -> activate cardiac vagal efferent nerve fibres
Often in men over 50
Orthostatic hypotension causes:
-Volume depletion
- Autonomic depletion
Use the acronym DAAD:
Drugs - BP, diuretics, TCA’s
Autonomic insufficiency - Parkinson’s, DM, shy-dragger, adrenal insufficiency
Alcohol
Dehydration
Volume depletion causes:
- Hemorrhage, vomiting, diarrhea
- Autonomic faliure - affects vasodilation and vasoconstriction - can be caused by primary autonomic faliure - ex. due to old age, parkinson’s disease
Pathophysiology of Syncope:
Global hypoperfusion of both the cerebral cortices or focal hypoperfusion of the reticular activating system in the midbrain
__% reduction in cerebral blood flow causes syncope
35
Cessation of cerebral perfusion for ____ seconds causes syncope
5-10
San Francisco Syncope Rule:
High risk for a serious cause of syncope:
40% mortality in 2 years after unexplained and recurrent syncope is anyone who has structural heart disease (CHF), anemia, hematocrit <30%, ECG abnormality, SOB, or htn (SBP<90mmhg)
Cardiac causes:
*** most dangerous
- Rarely causes syncope but may lower the threshold for syncope
- Arrhythmia
- Sturctural defects - aortic stenosis, hypertrophic cardiomyopathy, prosthetic vavle dysfunction, MI
- Great vessel defects - PE, acute aortic dissection
Neurocardiogenic syncope:
Vigorous myocardial contraction of relatively empty LV -> activates myocardial mechanoreceptors and vagal afferent nerve fibres that inhibit sympathetic activity and increase parasympathetic activity -> vasodilation and syncope
Drop in BP and fixed HR?
Dysautonomic disorder
Drop in BP and increase in HR?
Vasodialtion or volume depletion
Insignificantdrop in BP and marked HR increase
Postural orthostatic tachycardia
Orthostatic htn is defined as a fall in sys BP of at least __ mmHg or dia BP of at least __ mmHg when a person stands
20
10
Monitoring after Syncope:
History
Physical ex
Medication review
ECG
Carotid sinus massage to assess carotid sinus hypersensitivity - CONTRAINDICATED if carotid bruit present or TIA/stroke
High-risk work-up:
Holter monitor, echo, stress test, ischemic evaluation, posterior circulation imaging of the brain if you suspect neurological syncope
