Physiology and pathophysiology of syncope

Question 1

What is meant by a TLOC?

Answer 1

Transient Loss Of Consciousness

Question 2

What is the definition of a Transient Loss Of Consciousness (TLOC)?

Answer 2

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

Question 3

What are some causes of Transient Loss Of Consciousness?

Answer 3

Head trauma
Syncope
Epileptic seizures
Psychogenic pseudo-syncope
Psychogenic pseudo-seizures

Question 4

What is the definition of syncope?

Answer 4

Transient Loss Of Consciousness due to cerebral hypo-perfusion, characterised by rapid onset, short duration and spontaneous complete recovery

Question 5

What are the 3 main categories of syncope?

Answer 5

Reflex syncope
Orthostatic hypotension
Cardiac syncope

Question 6

What is meant by reflex syncope?

Answer 6

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

Question 7

What are the 3 main types of reflex syncope?

Answer 7

Vasovagal syncope
Situational syncope
Carotid Sinus syncope

Question 8

What causes vasovagal syncope?

Answer 8

Fainting is triggered by emotional distress or orthostatic stress

Question 9

What are some common prodromes of vasovagal syncope?

Answer 9

Pallor
Sweating
Nausea

Question 10

What is a prodrome?

Answer 10

An early syndrome of a disease or condition

Question 11

What are some way sin which vasovagal syncope can be averted?

Answer 11

Adopting a Horizontal Gravity Neutralisation Position
Leg crossing

Question 12

What is the main risk associated with vasovagal syncope?

Answer 12

Risk of injury
There is no association with increased mortality

Question 13

What are some treatment options for vasovagal syncope?

Answer 13

Education
Reassurance
Avoidance of triggers
Adequate hydration

Question 14

What causes situational syncope?

Answer 14

Faint during or immediately after a specific trigger

Question 15

What is micturition?

Answer 15

Urination

Question 16

What are some common causes of situational syncope?

Answer 16

Coughing
Micturition (Urination)
Swallowing

Question 17

What are some treatments for situational reflex syncope?

Answer 17

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)

Question 18

What is the cause of Carotid Sinus reflex syndrome?

Answer 18

Fainting triggered by mechanical manipulation of the neck (e.g. shaving, tight collars) or other associated conditions (e.g. Carotid artery atherosclerosis)

Question 19

What is another name for Carotid Sinus Reflex syncope?

Answer 19

carotid Sinus Hypersensitivity

Question 20

What is the main treatment option for carotid sinus reflex syncope?

Answer 20

Permanent cardiac pacing (Pacemaker)

Question 21

What causes Postural/Orthostatic hypotension?

Answer 21

Failure of baroreceptor response to gravitational shifts in the blood, when moving from a horizontal to anvertical position

Question 22

What are some common risk factors associated with orthostatic hypotension?

Answer 22

Age
Certain medication
certain diseases
Reduced intravascular volume
Prolonged bed rest

Question 23

What is defined as a positive result for an orthostatic hypotension test?

Answer 23

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)

Question 24

What are some common symptoms of orthostatic hypotension?

Answer 24

Dizziness
Lightheadedness
Blurred vision
Faintness
Falls

Question 25

What is the cause of cardiac syncope?

Answer 25

A cardiac event, resulting in a sudden drop in cardiac output

Question 26

What are some common causes of cardiac syncope?

Answer 26

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

Question 27

What should be included in the initial evaluation of a patient presenting with TLOC?

Answer 27

A careful history (Possibly from other too)
Full examination
Orthostatic blood pressure measurement
12-lead ECG

Question 28

What are some common features suggestive of cardiac syncope?

Answer 28

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