SYNCOPE Flashcards
What is syncope?
A transient, spontaneous loss of consciousness followed by complete recovery
What causes syncope?
Neurally-mediated reflex syncope
Orthostatic syncope
Cardiac syncope
Epileptic seizures
What causes syncope?
Global cerebral hypoperfusion due to an abrupt fall in blood pressure
What is neurally-mediated reflex syncope?
vasovagal: triggered by emotion, pain or stress. Often referred to as ‘fainting’
situational: faint with an identifiable trigger (cough, micturition, gastrointestinal)
carotid sinus syncope
What is vasovagal syncope? What is the pathophysiology?
Triggered by emotion, pain or stress
Triggering event ->
Cardioinhibitory response: increased parasympathetic activity that causes altered electrical activity in the heart manifesting as bradycardia (or higher degree of heart block).
Vasodepressor response: decreased sympathetic activity that leads to systemic vasodilatation and subsequent hypotension.
Cerebral hypoperfusion = temporary loss of conciousness
What’s the most common type of syncope?
Vasovagal syncope (over 1/3rd of cases)
What are classic triggers for vasovagal syncope?
Emotional events
Painful or noxious stimuli
Prolonged standing
Heat exposure
Physical exertion
Some patients may have no specific trigger, particularly in the elderly.
If there is a very specific trigger e.g. micturition its known as situational syncope
What are clinical features of vasovagal syncope?
Typically occurs when standing or sitting
Prodromal phase - lightheadidness, pallor, sweating, temp changes, palpitations, nausea, visual alteration, reduction in hearing
Brief loss of conciousness (8-12 seconds)
Post-syncope fatigue
How is vasovagal syncope diagnosed?
thorough history and clinical examination
Witness
During the event hypotension and bradycardia are commonly observed but physical exam is otherwise normal
Capillary BG
ECG monitoring
VBG
Bloods - FBC, U&E
Tilt-table test if recurrent (to see if syncope is accompanied by a severe cardioinhibitory response)
What is the tilt-table test?
The test first involves putting the patient on a motorised table with ECG monitoring. Continuous assessments are then made including beat-to-beat blood pressure, heart rate, symptoms, and ECG changes as the patient is moved from a supine position to a head-up position at 60-80º. The idea is to induce syncope and assess the changes on non-invasive monitoring. Provocation drugs may be used if syncope does not occur during passive monitoring.
A positive test for vasovagal syncope is suggested by the development of syncope during the test with evidence of a cardioinhibitory and/or vasodepressor response that leads to hypotension.
How do you manage vasovagal syncope?
Only required in recurrent cases
Conservative - trigger avoidance, pt education, increase fluid intake, increase salt intake, compression stockings, DVLA consideration
Medical therapy - fludrocortisone, midodrine
Other - older pt with significant cardioinhibitory response may be considered for permenant pacing
why should you increase salt intake for vasovagal syncope?
NaCl - increasing Na+ can increase blood volume
(Bare in mind you shouldn’t do this for pt with hypertension or hart disease)
How does fludrocortisone help manage vasovagal syncope?
It’s a potent mineralocorticoid that enhances fluid retention by acting on kidneys to increase Na+ and water retention
Increasing blood volume and blood pressure can reduce the risk of syncope
How does midodrine help manage vasovagal syncope?
Midodrine is an alpha-adrenergic receptor agonist that increases vascular tone
Limited evidence and side effects often lead to cessation e.g. supine hypertension and frequent urination
What is carotid sinus syndrome?
A type of neurally-mediated reflex syncope
Hypersensitivity of carotid sinus baroreceptor causes bradycardia and/or vasodilation
This can occur when pressure is applied to the neck, such as when wearing a tight collar or shaving, or as a result of a carotid sinus massage or other medical procedure.
What is situational syncope?
A type of neurally-mediated reflex syncope?
Fainting with an identifiable trigger
What are the 3 types of neurally-mediated reflex syncope?
Vasovagal syncope
Carotid sinus syndrome
Situational syncope
What is orthostatic hypotension?
a fall in systolic blood pressure of at least 20 mmHg (at least 30 mmHg in people with hypertension) and/or a fall in diastolic blood pressure of at least 10 mmHg within 3 minutes of standing.
What causes orthostatic hypotension?
Primary autonomic failure - parkinsons, Lewy body dementia
Secondary autonomic failure - diabetic neuropathy, amyloidosos, uraemia
Drug-induced
Volume depletion e.g. haemorrhage, diarrhoea, dehydration
Prolonged bed rest causing physical deconditioning
What drugs can cause orthostatic hypotension?
diuretics - can lead to dehydration
alcohol
vasodilators
Anti-hypertensives
Alpha-adrenoreceptor blockers
What can cause cardiac syncope?
Arrhythmias
Structural heart disease - Valvular heart disease, cardiomyopathy, congenital heart defects
Obstruction of blood flow - aortic stenosis, PE, hypertrophic cardiomyopathy, MI
Brugada syndrome
Long QT syndrome
Whats the most common cause of syncope in all age groups?
Reflex syncope
(Orthostatic and cardiac causes become progressively more common in older patients)
Outline the epidemiology of syncope?
1 in 2 people will experience syncope at some point in their life
1% of A&E visits are due to syncope
What are complications of syncope?
Injuries associated with sudden loss of conciousness
Whats the prognosis of syncope?
Vasovagal syncope and situational syncope are generally associated with a good overall prognosis.
Orthostatic hypotension is generally associated with a good prognosis although the person’s long-term prognosis may be affected by some of the possible underlying causes for the condition (such as diabetes and Parkinson’s disease).
An underlying cardiac cause for blackout is associated with a poorer prognosis
When should you suspect an underlying cardiac cause for syncope?
ECG abnormalities
Suspected/confirmed HF
Blackout occurring during exertion
Palpitations before loss of conciousness
FHx of sudden cardiac death in people younger than 40
New or unexplained breathlessness
Heart murmur
Blackout without prodromal symptoms in people >65 years.
When should you suspect epilepsy as an underlying cause for syncope?
Prodromal déjà vu, or jamais vu
A bitten tongue
Head-turning to one side during the blackout
Loss of bowel and bladder control
Unusual posturing
Prolonged limb-jerking
Confusion following the event
When should you suspect an uncomplicated vasovagal syncope?
An absence of features to suggest an alternative diagnosis (note: brief seizure activity can occur during uncomplicated faints and is not necessarily diagnostic of epilepsy) and
The presence of features suggestive of uncomplicated faint (the 3 ‘P’s):
Posture — blackout occurred after prolonged standing. Similar episodes may have been prevented by lying down.
Provoking factors — such as pain or a medical procedure.
Prodromal symptoms — such as sweating or feeling warm/hot before the blackout occurred.
When should you suspect situational syncope?
There are no features to suggest an alternative diagnosis and
Syncope is clearly and consistently provoked by straining during micturition (usually while standing), defecation, or by coughing or swallowing.
When should you suspect carotid sinus syndrome?
if the blackouts occurred while turning the head to one side, particularly in men aged 50 years or older.
When should you suspect orthostatic hypotension?
An absence of features suggesting an alternative diagnosis and
A typical history — light-headedness, dizziness, weakness, tunnel vision. Symptoms should not occur while supine, should get worse on standing, and should be relieved by sitting or lying down. Some people may present with recurrent or unexplained falls. Symptoms are often worse early in the morning, in hot environments, after meals, after standing motionless, and after exercise.
May also have underlying causes e.g. meds, prolonged bed rest, parkinsons etc
How should you investigate suncrope?
Capillary blood glucose, VBG, FBC, U&Es
cardiovascular examination
postural blood pressure readings
carotid sinus massage
tilt table test
24 hour ECG
How should you manage a pt with syncope?
Advise pt not to drive until specialist assessment
Refer to cardiac if suspecting cardiovascular cause or orthostatic hypotension and neurology if suspecting epilepsy
How should you manage orthostatic hypotension?
Consider likely causes, review drug therapy
Explain mechanisms causing blackouts
Lifestyle -
when going from supine to standing advise to sit first
Increase salt intake unless contraindicated
Drink strong tea or coffee
Drink >2L water a day
Avoid alcohol
Tilt head up during sleeping
Treat constipation aggressively as vasalva manouvre can worsen syncope
