Week 9: Syncope

Question 1

What is syncope, describe its features and pathophysiology?

Answer 1

Transient, self- limited loss of consciousness due to acute global impairment of cerebral blood flow (hypo perfusion)

Question 2

What are some differentials for syncope

Answer 2

o Seizures – clonic/tonic movements with eyes open, post-ictal confusion
o Vertebrobasilar ischemia / TIA – look for neurological deficit
o Hypoxemia – abnormally low level of oxygen in the blood.
o Hypoglycaemia - abnormally low level of glucose in the blood.
o Cardiac arrhythmia, orthostatic hypotension, Sepis (fever), tight ties (CSS)

Question 3

Causes of syncope can be divided into 3 categories- what are they?

Answer 3

1. Neurally mediated syncope (reflex syncope)
2. Orthostatic hypotension
3. Cardiac syncope

Question 4

Preceding Symptoms and red flags

Answer 4

• Syncope + headache= subarachnoid or intracranial hemorrhage
• Syncope + neuro deficit= stroke / TIA or intracranial bleed
• Syncope + confusion= seizure
• Syncope + chest pain= MI, PE, or aortic dissection
• Syncope + back/abdominal pain in older patient= abdominal aortic aneurysm (AAA)
• Syncope + positive HCG= ectopic pregnancy
• Past medical history- is this recurrent syncope or is this new? Ask for history of seizures, MI, stroke/TIA, known AAA, family history of heart disease
• “PASS OUT” pneunomic – see attached PDF

Question 5

PASS OUT

view attached PDF

Answer 5

Pressure (hypotensive causes)
Arrhythmias
Seizures 
Sugar (hypo/ hyperglycemia)
Output 
Unusual Causes 
Transient Ischemic Attacks

Question 6

What is some pathophysiology of Syncope?

Answer 6

o The upright posture causes physiologic stress which results in 500-1000ml of blood pooling in the lower extremities and splanchnic circulation.
o This initiates a reflex response in the baroreceptors in the aortic arch and carotid sinus.
o This results in an increase in peripheral resistance, venous return to the heart and cardiac output = prevents a drop in blood pressure.
o If this response fails cerebral hypoperfusion occurs.

Question 7

Neurally mediated syncope can be subdivided in 2 ways:

view slides 8 and 9

Answer 7

o Can be subdivided ways

1. Based on the afferent pathway and provocative trigger
2. Vasovagal (the common faint)- is provoked by an intense emotion, pain and/or orthostatic stress
3. Situational reflex – specific localised stimuli that provoke a reflex vasodilation and bradycardia. A pathophysiological cause – G- I, G-U, pulmonary system, heart, carotid artery.
4. Predominant efferent pathway
5. Vasodepressor – predominantly due to efferent, sympathetic, vasocontrictor failure
6. Cardioinhibitory – predominantly associated with bradycardia or asystole due to increased vagal outflow
7. Mixed – both vagal and sympathetic reflex changes

Question 8

What are the features and treatment of Neurally mediated syncope?

Answer 8

Features: 
• In addition to the usual prodrome features of syncope people who have neurally mediated syncope may exhibit the following;
o Diaphoresis–excessivesweating o Pallor
o Palpitations
o Nausea
o Hyperventilation o Yawning

Treatment:
• Reassurance
• Avoid the provocative stimuli
• Increase plasma volume using fluid and salt
• Getting the patient to cross their legs, tighten their fist or arm as they feel the prodrome may prevent the syncope. (these all increase intravascular pressure)

Question 9

What is orthostatic hypotension?
What is the pathophysiology and causes of it?
What are the features?
Treatment?

Answer 9

Orthostatic Hypotension: A reduction in a systolic BP of at least 20mmHgor diastolic blood pressure of at least 10mmHg within 3 minutes of staining or head up tilt on a tilt table.

Pathophysiology:
o There is no increase in heart rate to compensate for the blood pooling
due to autonomic dysfunction.

Causes:
o Central and peripheral autonomic nervous system dysfunction eg Parkinsons, as well as pure ANS failure
o Iatrogenic
o Dehydration, Endocrine – thyroid, Addisons (Adrenal insufficency),
diabetis
o Heart – valve, myocardial infarction, fever, prolonged bed rest. Rx ?

Features:
o Features
• Patients would experience the following symptoms after a sudden postural change
o Lightheadedness o Dizziness
o Pre-syncope
• There may also be nonspecific symptoms such as; o Generalisedweakness
o Fatigue
o Cognitiveslowing
o Leg buckling o Headache
o Visualblurring
• Neck pain – particularly suboccipital, posterior cervical and shoulder region, may be the only symptom
• Symptoms may be exacerbated by o Exertion
o Prolongedstanding
o Increasedambienttemperature o Meals

Treatment:
• Remove reversal causes
• Patient education
o Staged moves from supine to upright
o Warn about the hypotensive effects of meal digestion
o Exercises to increase intravascular pressure
o Raising the head of the bed to reduce supine hypertension o Increase plasma volume by increasing fluid and salt intake
• Medication

Question 10

What is cardiac syncope?
Causes?
Treatment?

Answer 10

Cardiac syncope
• A decrease in cardiac output due to heart disease,
Causes
• Caused by arrhythmias and structural heart disease

o Treatment
• This is out of our domain and needs referral to a specialist.