Overview of physiology and pathophysiology of syncope Flashcards
General explanation of syncope?
Specific form of a transient loss of consciousness
3 types of syncope?
Reflex
Orthostatic hypotension
Cardiac
Sub types of reflex syncope?
Vasovagal (VVS)
Carotid sinus (CCS)
Situational
Transient Loss of Consciousness (TLOC) definition?
A state of real or apparent loss of consciousness with loss of awareness, characterized by amnesia for the period of unconsciousness, loss of motor control, loss of responsiveness and a short duration.
What conditions can cause TLOC?
Head trauma Syncope Epileptic seizures TLOC mimics (psychogenic, pseudo syncope) Other causes
Definition of syncope?
Transient loss of consciousness due to cerebral hypoperfusion, characterized by rapid onset, short duration and spontaneous complete recovery
Reflex syncope?
All types of syncope in which neural reflexes modify HR and/or vascular tone (vasodepression) hence predisposing to a fall in MAP (sysetmic hypotension) of sufficient severity to affect cerebral perfusion causing a transient period of cerebral hypoperfusion resulting syncope or near syncope
Reflex syncope is uncommon. True or false?
False. It is common
Events that occur in reflex syncope?
When reflex is activated
this causes cardioinhibition through vagal stimulation
causing decreased HR and CO
AND/OR
Vasodepression through depression of sympathetic activity to blood vessels
Decreasing systemic vascular resistance (vasodilation), venous return, stroke volume and CO
This decreases in everything causes decrease in MAP
=
Cerebral hypoperfusion and syncope/ near syncope
Most common type of syncope?
Vasovagal
What causes vasovagal syncope?
Faint is caused by emotional stress or orthostatic stress
What symptoms occur in vasovagal syncope?
Palor
Sweating
Nausea
How can vasovagal syncope be averted?
Lying down )adopting horizontal gravity neutralisation)
Leg crossing
Both of these increase venous return
Main risk of Vasovagal syncope?
Injury when falling
VVS is not associated with increased mortality. True or false?
True
Treatment of VVS?
Education
Reassurance
Avoidance of triggers
Adequate hydration
What happens in situational syncope?
Faint during or immediately after a specific trigger. Eg coughing, urination, swallowing
Vasovagal syncope is less common than situational syncope. True or false?
False. Vasovagal is most common
Treatment for situational syncope?
Treat the cause eg if it is a cough
Advise patient to lie down if possible
Avoid dehydration and XS alcohol
However some cases of cardiac pacing may be required in some cases
What is the carotid sinus reflex triggered by?
Mechanical manipulation of the neck eg shaving, tight collar
Who is CSS more common in?
Elderly males
When might CSS occur?
After head and neck surgery or radiation
Treatment of carotid sinus syncope?
Permanent pacing is generally recommended
Associated conditions with CSS?
Carotid artery atherosclerosis- not clear if this is causative or not
Another reason why people have syncope?
Postural hypotension
What is postural hypotension?
Results from failure of baroreceptor responses to gravitational shifts in blood, when moving from horizontal to vertical position
Other term for postural hypotension?
Orthostatic hypotension
Risk factors for orthostatic hypotension?
Age related Medications Certain diseases Reduced intravascular disease Prolonged bed rest
Positive result showing postural hypotension?
Drop in blood pressure within 3 minutes of standing up from lying position
Systolic= Atleast 20mmHg
Diastolic= 10mmHg
Symptoms of postural hypotension?
Those of cerebral hypoperfusion- Dizzy, light headed blurred vision, faintness and falls
What is cardiac syncope caused by?
Cardiac event caused resulting in a sudden drop in cardiac output
What can cardiac syncope be caused by?
Arrhythmias- Resulting in tachy or bradychardia
Acute myocardial infarction
Structural cardiac dieases - aortic stenosis, hypertrophic cardiomyopathy
Other cardiovascular diseases- pulmonary embolism, aortic dissection
Initial evaluation of a patient presenting with TLOC?
Careful history
Full physical examination
Orthostatic BP measurement
12 lead ECG
Features that suggest cardiac syncope?
Syncope during excretion or when supine
Presence of structural cardiac abnormality or coronary heart disease
Family history of sudden death at a young age
Sudden onset palpitations immediately followed by syncope
Finding on ECG suggestive of arrhythmic syncope