Physiology and pathophysiology of syncope Flashcards
What is meant by a TLOC?
Transient Loss Of Consciousness
What is the definition of a Transient Loss Of Consciousness (TLOC)?
A state of real or apparent loss of consciousness with loss of awareness, characteristics of amnesia during the period of unconsciousness, loss of motor control, loss of responsiveness and of a short duration
What are some causes of Transient Loss Of Consciousness?
Head trauma
Syncope
Epileptic seizures
Psychogenic pseudo-syncope
Psychogenic pseudo-seizures
What is the definition of syncope?
Transient Loss Of Consciousness due to cerebral hypo-perfusion, characterised by rapid onset, short duration and spontaneous complete recovery
What are the 3 main categories of syncope?
Reflex syncope
Orthostatic hypotension
Cardiac syncope
What is meant by reflex syncope?
All types of syncope in which neural reflexes modify heart rate (Cardioinhibition) and/or vascular tone (Vasodepression) which causes a fall in MAP of sufficient severity to affect cerebral perfusion
What are the 3 main types of reflex syncope?
Vasovagal syncope
Situational syncope
Carotid Sinus syncope
What causes vasovagal syncope?
Fainting is triggered by emotional distress or orthostatic stress
What are some common prodromes of vasovagal syncope?
Pallor
Sweating
Nausea
What is a prodrome?
An early syndrome of a disease or condition
What are some way sin which vasovagal syncope can be averted?
Adopting a Horizontal Gravity Neutralisation Position
Leg crossing
What is the main risk associated with vasovagal syncope?
Risk of injury
There is no association with increased mortality
What are some treatment options for vasovagal syncope?
Education
Reassurance
Avoidance of triggers
Adequate hydration
What causes situational syncope?
Faint during or immediately after a specific trigger
What is micturition?
Urination
What are some common causes of situational syncope?
Coughing
Micturition (Urination)
Swallowing
What are some treatments for situational reflex syncope?
Treatment of the cause (e.g. cough)
Advise the patient to lie down
Avoid dehydration and excessive alcohol
Cardiac permanent pacing may be required (Pacemaker)
What is the cause of Carotid Sinus reflex syndrome?
Fainting triggered by mechanical manipulation of the neck (e.g. shaving, tight collars) or other associated conditions (e.g. Carotid artery atherosclerosis)
What is another name for Carotid Sinus Reflex syncope?
carotid Sinus Hypersensitivity
What is the main treatment option for carotid sinus reflex syncope?
Permanent cardiac pacing (Pacemaker)
What causes Postural/Orthostatic hypotension?
Failure of baroreceptor response to gravitational shifts in the blood, when moving from a horizontal to anvertical position
What are some common risk factors associated with orthostatic hypotension?
Age
Certain medication
certain diseases
Reduced intravascular volume
Prolonged bed rest
What is defined as a positive result for an orthostatic hypotension test?
A drop within 3 minutes of standing, from a lying position in either:
- Systolic blood pressure of at least 20mmHg (With or without symptoms)
- Diastolic blood pressure of at least 10mmHG (With symptoms)
What are some common symptoms of orthostatic hypotension?
Dizziness
Lightheadedness
Blurred vision
Faintness
Falls
What is the cause of cardiac syncope?
A cardiac event, resulting in a sudden drop in cardiac output
What are some common causes of cardiac syncope?
Arrhythmias that result in either bradycardia or tachycardia
Acute myocardial infarction
Structural cardiac disease e.g. aortic stenosis, hypertrophic cardiomyopathy
Other CVDs e.g. pulmonary embolism, aortic dissection
What should be included in the initial evaluation of a patient presenting with TLOC?
A careful history (Possibly from other too)
Full examination
Orthostatic blood pressure measurement
12-lead ECG
What are some common features suggestive of cardiac syncope?
Syncope during exercise or when supine
Presence of a structural cardiac abnormality
Family history of sudden death at a young age
Sudden, onset palpitations immediately followed by syncope
Findings on an ECG suggestive of arrhythmic syncope
