Syncope Flashcards
Definition of Syncope
Transient loss of consciousness due to cerebral hypoperfurion, characterised by rapid onset, short duration, and spontaneous complete recovery
Syncope 3 classifications
Reflex Syncope
* vasovagal
* situational
* carotid sinus syncope
Orthostatic hypotension
Cardiac Syncope
What are 3 types of reflex Syncope
Vasovagal Syncope (VVS) - most common type of Syncope
Situational Syncope - less common than vasovagal syncope
Carotid sinus Syncope (CSS) - more common in elderly and males
Cause of Postural hypotension
Results from failure of baroreceptor responses to gravitational shifts in blood, when moving from horizontal to vertical position
Risk factors of postural (Orthostatic) hypotension
Age related
Medications
Certain diseases
Reduced intravascular volume
Prolonged bed rest
What is Postural (orthostatic) Hypotension indicated by?
Orthostatic hypotension is indicated by a drop within 3 minutes of standing from lying position of at least 20mmHg in systolic BP (with with or without symptoms) or a drop pf diastolic pressure of at least 10mmHg (WITH symptoms)
Causes of cardiac syncope
Caused by a cardiac event resulting in sudden drop in cardiac output:
- arrhythmias: regulating in bradycardia/tachycardia
- acute MI
- structural cardiac disease e.g. Aortic stenosis, hypertrophic caerdiomyopathy
- other cardiovascular disease e.g. pulmonary embolism, aortic dissection
Symptoms of postural (orthostatic) hypotension
May include those of Cerebral hypoperfusion: lightheadedness, dizziness, blurred vision, faintness and falls
What are features that suggest cardiac syncope?
- syncope during excercise
- structural cardiac abnormality or coronary disease
- family history of sudden death at young age
- sudden onset palpitations immediacy followed by syncope
- ECG suggestive of arrhythmic syncope
What is transient loss of consciousness (TLOC)
A state of real or apparent loss of consciousness with loss of awareness, characterised by amnesia for the period of unconsciousness, loss of motor control, loss of responsiveness, and a short duration
What can results in transient loss of consciousness (TLOC)?
Head trauma (head TLOC)
Syncope
Epileptic seizures
TLOC mimics (e.g. psychogenic pseudo-syncope, psychogenic pseudo-seizures)
Other causes
careful history must be obtained from a witness of TLOC
What is reflex syncope (for ALL types)
Neural reflexes modify heart rate (cardio inhibition) and/or vascular tone (vasodepression), hence, predisposing to a fall in mean arterial blood pressure (systematic hypotension) of sufficient severity to affect cerebral perfusion causing a transient period of cerebral hypoperfusion resulting in syncope or near syncope
What is the mechanism of reflex syncope to cause cerebral hypoperfusion and syncope/near syncope?
When activated the reflex causes cardioinhibition via vagal nerve stimulation -> decreases HR (bradycardia) and CO
And/or causes vasodepression via depression of sympathetic activity to blood vessels -> decreasing systemic vascular resistance (vasodilation), venous return, stroke volume and CO
Decrease in CO and SVR = decrease MAP
Resulting in cerebral hypoperfusion and syncope or near syncope
What does vasovagal reflex syncope trigger and why?
What is associated symptoms?
A faint - caused by emotional stress (e.g. pain,fear, blood phobia) or orthostatic stress]
Associated with typical prodrome (pallor, sweating, nausea)
How can vasovagal syncope be averted sand treated?
Averted by: adopting horizontal gravity neutralisation position or leg crossing - both increases venous return
Treatment: education, reassurance, avoid triggers if possible and adequate hydration
