3.2.5. Clinical Reasoning Syncope

Question 1

What is syncope?

Answer 1

syncope = “transient loss of consciousness NOT due to seizure or trauma”

Question 2

What does “Ictal” mean

Answer 2

“Ictal” = pertaining to seizure(s)

Question 3

_____ _____ present in 94% of seizure cases

Answer 3

postictal confusion present in 94% of seizure cases

Question 4

What trick can we use to help rule out syncope?

Answer 4

Use presence of tongue-biting to RULE OUT syncope (16 times more likely in seizure vs syncope)

Question 5

Describe the cerebrovascular events that result in syncope.

Answer 5

Your brain can’t withstand nearly any loss of oxygen… 5-10 sec range of “hardiness” on average, just keeps decreasing w/age

Question 6

Major implications for loss of consciousness (LOC):

Answer 6

Bilateral cortical dysfunction

Brainstem ascending reticular activating system (RAS)

Question 7

2 rare causes of LOC that you wouldn’t expect to be rare

Answer 7

Thus, carotid artery occlusion or cerebrovascular trauma rarely causes LOC

Question 8

Two types of syncope

Answer 8

cardiac and non cardiac

Question 9

What are the electrical cardiac causes of syncope?

Answer 9

Fast Arrhythmias

Slow arrhythmias

Question 10

Most common cause of fast arrhythmia syncope?

Answer 10

V tach

Question 11

Relate SVT to syncope

Answer 11

SVT = minor contributor, rarely causes LOC (causes death more often than loss of consciousness)

Question 12

What types of slow arrhythmias can cause syncope?

Answer 12

Sick sinus syndrome = the SA node becomes fibrotic b/c of age, thus loses regular/dependable automaticity

AV block = can’t conduct signals and contract heart in coordinated fashion

Question 13

What types of mechanical instabilities do we have that can cause syncope?

Answer 13

1. Valvular
2. Sub-valvular
3. Pulmonary embolus
4. Anomalous Coronary Occlusion
5. Atrial Myxoma
6. Subclavian Steal

Question 14

What valvular mechanical instabilities are there that can cause syncope?

Answer 14

Aortic stenosis in older patients and hypertrophic cardiomyopathy in younger patients

Question 15

What is an atrial myxoma?

Answer 15

atrial myxoma (tumor that blocks the mitral orifice; very uncommon)

Question 16

What is a subclavian steal?

Answer 16

subclavian steal (atherosclerosis in brachial artery, prevents blood flow from going to cerebrum)

Question 17

Why are Pts fainting if the heart isn’t affected directly???

Answer 17

Most important cause: neurally-mediated reflex syncope (NMS) (“fainting”, “vaso-vagal syncope”)

Question 18

Secondary results due to vaso vagal syncope

Answer 18

Generally benign, but in elderly can result in head trauma due to sudden onset

Question 19

Causes of circulating hypovolemia that can lead to neurally-mediated reflex syncope:

Answer 19

Dehydration, being hungover, standing at attention & locking knees for too long

Question 20

Cause of syncope as related to the sympathetic nervous system

Answer 20

Exaggerated sympathetic activation (inappropriately excessive fight/flight response) can cause syncope

Question 21

Describe Head Up Table Tilt

Answer 21

Nml response: as BP drops, baroreceptors are unloaded, so HR decreases but BP is kept stable

Abnml: sudden drop in BP AND HR, so the initially-induced drop in BP is exaggerated by the body’s abnormal response

You must lower their head ASAP so they don’t go into asystole and die!!

Question 22

Relate a ventricular abnormality to syncope

Answer 22

Physical contact of ventricles (b/c little/no blood is being pumped) can stimulate the brain to act and induce venous return

Causes vasodilation, BUT this kills your BP and makes NO blood return to the heart at all

Question 23

Common symptoms prior to a cardiac related syncopal episode

Answer 23

often none prior to CV syncope (sudden lights out, or few seconds before fainting)

Question 24

What symptoms suggest a neural mediation of syncope?

Answer 24

Nausea, sweating, abd discomfort, etc STRONGLY SUGGESTS NEURAL MEDIATION

Question 25

_____ _____ seen in 94% (feel like having been hit by a truck after waking up)

Answer 25

Postdromal fatigue seen in 94% (feel like having been hit by a truck after waking up)

Question 26

Exercise induced syncope suggests ______, but POST-exercise suggests _____.

Answer 26

Exercise induced syncope suggests CV, but POST-exercise suggests NMS

Question 27

How is family history related to syncope?

Answer 27

Family history: member dying of inexplicable causes

Question 28

Red Flags for Syncope

Answer 28

1. high-risk occupations in general (if so, they need to be immediately relieved from their duties)

pilots, school bus drivers (sorry Ms Frizzle), etc

2. elderly Pts are especially at a high risk for CV syncope b/c about ⅓ of them actually have it

Question 29

Most dangerous medication for syncope

Answer 29

alpha-adrenergics mess up systemic vascular resistance

Question 30

Most important vitals finding for syncope?

Answer 30

Vitals single most important (drop >20mmHg when orthostatic suggests intravascular depletion or autonomic dysfunction)

Question 31

Relate murmurs to syncope

Answer 31

may be indicative of systolic ejection murmur due to aortic stenosis

confirm w/Valsalva and/or standing for hypertrophic cardiomyopathy

Question 32

Relate CHF to syncope

Answer 32

general signs/symptoms of heart failure suggest high risk overall

Question 33

When is echocardiography not helpful?

Answer 33

echocardiography is often helpful
useful for most patients -

EXCEPT FOR younger patients w/obvious NMS

Question 34

Should we always do an EKG for syncopal patients?

Answer 34

99.999% of the time do an EKG to record new ischemia, old infarcts, long QT, LVH…