Overview of physiology and pathophysiology of syncope

Question 1

General explanation of syncope?

Answer 1

Specific form of a transient loss of consciousness

Question 2

3 types of syncope?

Answer 2

Reflex
Orthostatic hypotension
Cardiac

Question 3

Sub types of reflex syncope?

Answer 3

Vasovagal (VVS)
Carotid sinus (CCS)
Situational

Question 4

Transient Loss of Consciousness (TLOC) definition?

Answer 4

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.

Question 5

What conditions can cause TLOC?

Answer 5

Head trauma 
Syncope 
Epileptic seizures 
TLOC mimics  (psychogenic, pseudo syncope)  
Other causes

Question 6

Definition of syncope?

Answer 6

Transient loss of consciousness due to cerebral hypoperfusion, characterized by rapid onset, short duration and spontaneous complete recovery

Question 7

Reflex syncope?

Answer 7

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

Question 8

Reflex syncope is uncommon. True or false?

Answer 8

False. It is common

Question 9

Events that occur in reflex syncope?

Answer 9

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

Question 10

Most common type of syncope?

Answer 10

Vasovagal

Question 11

What causes vasovagal syncope?

Answer 11

Faint is caused by emotional stress or orthostatic stress

Question 12

What symptoms occur in vasovagal syncope?

Answer 12

Palor
Sweating
Nausea

Question 13

How can vasovagal syncope be averted?

Answer 13

Lying down )adopting horizontal gravity neutralisation)
Leg crossing

Both of these increase venous return

Question 14

Main risk of Vasovagal syncope?

Answer 14

Injury when falling

Question 15

VVS is not associated with increased mortality. True or false?

Answer 15

True

Question 16

Treatment of VVS?

Answer 16

Education
Reassurance
Avoidance of triggers
Adequate hydration

Question 17

What happens in situational syncope?

Answer 17

Faint during or immediately after a specific trigger. Eg coughing, urination, swallowing

Question 18

Vasovagal syncope is less common than situational syncope. True or false?

Answer 18

False. Vasovagal is most common

Question 19

Treatment for situational syncope?

Answer 19

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

Question 20

What is the carotid sinus reflex triggered by?

Answer 20

Mechanical manipulation of the neck eg shaving, tight collar

Question 21

Who is CSS more common in?

Answer 21

Elderly males

Question 22

When might CSS occur?

Answer 22

After head and neck surgery or radiation

Question 23

Treatment of carotid sinus syncope?

Answer 23

Permanent pacing is generally recommended

Question 24

Associated conditions with CSS?

Answer 24

Carotid artery atherosclerosis- not clear if this is causative or not

Question 25

Another reason why people have syncope?

Answer 25

Postural hypotension

Question 26

What is postural hypotension?

Answer 26

Results from failure of baroreceptor responses to gravitational shifts in blood, when moving from horizontal to vertical position

Question 27

Other term for postural hypotension?

Answer 27

Orthostatic hypotension

Question 28

Risk factors for orthostatic hypotension?

Answer 28

``` Age related Medications Certain diseases Reduced intravascular disease Prolonged bed rest ```

Question 29

Positive result showing postural hypotension?

Answer 29

Drop in blood pressure within 3 minutes of standing up from lying position Systolic= Atleast 20mmHg Diastolic= 10mmHg

Question 30

Symptoms of postural hypotension?

Answer 30

Those of cerebral hypoperfusion- Dizzy, light headed blurred vision, faintness and falls

Question 31

What is cardiac syncope caused by?

Answer 31

Cardiac event caused resulting in a sudden drop in cardiac output

Question 32

What can cardiac syncope be caused by?

Answer 32

Arrhythmias- Resulting in tachy or bradychardia Acute myocardial infarction Structural cardiac dieases - aortic stenosis, hypertrophic cardiomyopathy Other cardiovascular diseases- pulmonary embolism, aortic dissection

Question 33

Initial evaluation of a patient presenting with TLOC?

Answer 33

Careful history Full physical examination Orthostatic BP measurement 12 lead ECG

Question 34

Features that suggest cardiac syncope?

Answer 34

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