Syncope

Question 1

What is syncope?

Answer 1

transient loss of consciousness (TLOC) due to transient global cerebral hypoperfusion
- characterised by rapid onset, short duration and spontaneous complete recovery

TLOC is a state of real or apparent loss of consciousness with a loss of awareness
- characterised by amnesia for a short period of unconsciousness, abnormal motor control and loss of responsiveness

Question 2

What are the types of transient loss of consciousness (TLOC)?

Answer 2

non-traumatic TLOC
- syncope = reflex, cardiac or orthostatic hypotension
- epileptic seizures = generalised (T/C/TC/A)

traumatic TLOC
- psychogenic
- subarachnoid haemorrhage

Question 3

What are the types of neurally mediated syncope?

Answer 3

vasovagal
- caused the brain overreacting to certain triggers
= fear, pain, phobia

situational
- micturition, GI stimulation, defacation

carotid sinus syndrome
- syncope caused by pressure applied to carotid artery (looking up, turning the neck)

non-classical forms
- without prodromes or apparent triggers

Question 4

What is carotid sinus syndrome?

Answer 4

• syncope caused by pressure applied to carotid artery (looking up, turning the neck)

typically in elderly patients, mostly men

have a predilection to atherosclerotic cardiovascular disease

Question 5

What is orthostatic syncope?

Answer 5

syncope caused by sudden change in posture

more common in the elderly

triggers
- dehydration
- excessive diuresis
- anti-hypertensives
- chronic alcoholism
- parkinson’s disease
- autonomic dysfunction = diabetes

Question 6

What is cardiac syncope?

Answer 6

a TLOC due to a defect, either structural or electrical, which prevents the generation of enough cardiac output to perfuse the brain adequately

can be caused by
- cardiac arrhythmias
- channelopathies

Question 7

What is POTS syndrome?

Answer 7

postural tachycardia syndrome
- abnormal increase in heart rate that occurs after sitting up/standing

Question 8

What is pathophysiology of syncope?

Answer 8

transient abrupt fall in blood pressure resulting in global cerebral hypoperfusion
- fluid shifts and inadequate venous return leads to reduced cardiac output
- peripheral vessels are not able to compensate

Autoregulation and central venous pressure may be altered in conditions such as labile HTN and DM make the patients more susceptible

Question 9

How can patients be tested for syncope?

Answer 9

carotid sinus massage
- pressure given at the site can produce hypotension and reflex slowing of the heart rate
= positive test is an asystole of more than 3 seconds and/or fall in BP of more than 60 mmHg, must listen for carotid bruits

active standing test
- changing from supine to upright posture causes a large gravitational shift of blood from the chest to the venous capacitance system below the diaphragm
= positive if there is a drop of systolic BP of 20 mmHg or less than 90 mmHg within 3 minutes of standing

tilt table testing (gold standard)

Question 10

What are non-pharmacological treatments for syncope?

Answer 10

avoidance of the trigger factors
increase fluid intake
increasing the salt intake may help in certain patients who have low risk of heart disease

physical counterpressure manoeuvres (PCM)
- leg crossing, hand grip and arm tensing produce significant BP increase during the impending phase of a syncopal attack
= may delay or avoid the LOC in most cases

Question 11

What are pharmacological treatments for syncope?

Answer 11

fludrocortisone
- acts as a mineralocorticoid
= sodium / water retention and potassium excretion
= check for hypokalaemia, pedal oedema and fluid retention

midodrine
- alpha 2 agonist
= activates alpha-adrenergic receptors of the arteriolar and venous vasculature
= avoid in older males with urological problems as it may cause difficulty with urinary outflow

droxidopa
- synthetic amino acid precursor that acts as a prodrug to noradrenaline