Syncopy Flashcards
Define a transient loss of consciousness
A state of real or apparent loss of consciousness with loss of awareness
Characterised by:
- amnesia (for duration of unconsciousness)
- loss of motor control
- loss of responsiveness
- short duration
List some of the characterising features of a transient loss of consciousness
- amnesia (for duration of unconsciousness)
- loss of motor control
- loss of responsiveness
- short duration
Is syncope the only cause of a transient loss of consciousness?
No
other things like head trauma, epilepsy etc. can cause it
Define syncope
Transient loss of consciousness due to cerebral hypoperfusion
List the characteristics of syncopy
- rapid onset
- short duration
- spontaneous full recovery
Define cerebral hypoperfusion
Reduced blood perfusion of the brain
List the types of syncope
- Reflex syncope (vasovagal, situational, carotid sinus)
- Orthostatic hypotension
- Cardiac syncope
Define reflex syncope
Syncope where neural reflexes modify heart rate and/or vascular tone
Describe the basic process that causes reflex syncope
Neural reflexes decrease heart rate and/or vascular tone --> Predisposing to a fall in MAP --> MAP fall causes cerebral hypotension --> Transient cerebral perfusion decreased --> Syncope (or near syncope)
What is the most common type of syncope?
Vasovagal syncope
Describe how neural reflexes decrease heart rate and/or vascular tone in reflex syncope
And the effect this has on MAP
Heart rate decrease:
- Vagal stimulation
- Decreased heart rate
- Cardiac output decreased
- MAP decreased
Vascular tone decrease:
- Decrease in vasomotor tone
- SVR decrease, venous return decrease, SV decrease
- Cardiac output and thus MAP decreases
Define vascular tone
The degree of constriction of a blood vessel
Decreased tone = vasodilation
Increased tone = vasoconstriction
List the types of reflex syncope
- Vasovagal
- Situational
- Carotid sinus
Describe vasovagal reflex syncope
Describe its prodrome
Aversion?
- Due to emotional distress (or orthostatic stress)
- Typical prodrome (sweating, pallor, nausea)
- Can be averted during prodrome (lie down - increase venous return)
- Most common type of syncope
What is the main risk of vasovagal reflex syncope?
Injury due to falling over
What is the treatment for vasovagal reflex syncope?
- Education on triggers
- Avoidance of triggers
- Adequate hydration
Is vasovagal reflex syncope linked to increased mortality?
No
Describe situational reflex syncope
- Syncope during/immediately after a specific stimulus
e. g. cough, swallowing, micturition - Less common
Describe the treatment for situational reflex syncope
- Treat the stimulus (e.g. cough)
- Advise patient lies down during stimulus (e.g. coughing)
- Avoid dehydration and excessive alcohol
- Cardiac pacemaker (if bad)
Describe carotid sinus reflex syncope
Syncope triggered by mechanical manipulation of the neck
- more common in elderly, and males
- associated with atherosclerosis
Describe the treatment for carotid sinus reflex syncope
- Cardiac pacemaker
What events can predispose to carotid sinus reflex syncope
- head and neck surgery
- radiation of the head and neck
Define postural (orthostatic) hypotension
Hypotension due to the failure of the baroreceptor reflex to respond to gravitational shifts in blood (usually when standing up)
List the risk factors of postural (orthostatic) hypotension
- Age related
- Medications
- Certain diseases
- Reduced intravascular volume
- Prolonged bed rest
What are the signs and symptoms of postural (orthostatic) hypotension?
- syncope
- lightheadedness
- dizziness
- blurred vision
- faintness
- falls
What is the clinical test for postural (orthostatic) hypotension?
Within 3 mins of standing from lying down, either:
- Systolic Bp drop of 20 mmHg
or - Diastolic Bp drop of 10 mmHg (with symptoms)
Describe cardiac syncope
Syncope due to a cardiac event that causes a sudden drop in cardiac output
List possible causes of cardiac syncope
- Arrhythmias: resulting in bradycardia or tachycardia
- Acute Myocardial infarction
- Structural Cardiac Disease: e.g. aortic stenosis, hypertrophic cardiomyopathy
- Other Cardiovascular Disease: e.g. pulmonary embolism, aortic dissection
How does an arrhythmia that causes tachycardia result in the decreased cardiac output seen in cardiac syncope?
The increased HR doesn't allow for complete filling of the ventricles --> Stroke volume decreased --> Cardiac output decreases
Describe findings that suggest cardiac syncope
- Syncope during excretion or when supine
- Presence of a structural cardiac abnormality or coronary heart disease
- A family history of sudden death at young age
- Sudden onset palpitations immediately followed by syncope
- Findings on ECG suggestive of arrhythmic syncope
Describe how to initially evaluate a patient presenting with transient loss of consciousness
- Careful history
- Any witnesses
- Fully physical examination
- Orthostatic blood pressure measurement
- 12-lead ECG
