3.2.5. Clinical Reasoning Syncope Flashcards
What is syncope?
syncope = “transient loss of consciousness NOT due to seizure or trauma”
What does “Ictal” mean
“Ictal” = pertaining to seizure(s)
_____ _____ present in 94% of seizure cases
postictal confusion present in 94% of seizure cases
What trick can we use to help rule out syncope?
Use presence of tongue-biting to RULE OUT syncope (16 times more likely in seizure vs syncope)
Describe the cerebrovascular events that result in syncope.
Your brain can’t withstand nearly any loss of oxygen… 5-10 sec range of “hardiness” on average, just keeps decreasing w/age
Major implications for loss of consciousness (LOC):
Bilateral cortical dysfunction
Brainstem ascending reticular activating system (RAS)
2 rare causes of LOC that you wouldn’t expect to be rare
Thus, carotid artery occlusion or cerebrovascular trauma rarely causes LOC
Two types of syncope
cardiac and non cardiac
What are the electrical cardiac causes of syncope?
Fast Arrhythmias
Slow arrhythmias
Most common cause of fast arrhythmia syncope?
V tach
Relate SVT to syncope
SVT = minor contributor, rarely causes LOC (causes death more often than loss of consciousness)
What types of slow arrhythmias can cause syncope?
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
What types of mechanical instabilities do we have that can cause syncope?
- Valvular
- Sub-valvular
- Pulmonary embolus
- Anomalous Coronary Occlusion
- Atrial Myxoma
- Subclavian Steal
What valvular mechanical instabilities are there that can cause syncope?
Aortic stenosis in older patients and hypertrophic cardiomyopathy in younger patients
What is an atrial myxoma?
atrial myxoma (tumor that blocks the mitral orifice; very uncommon)
What is a subclavian steal?
subclavian steal (atherosclerosis in brachial artery, prevents blood flow from going to cerebrum)
Why are Pts fainting if the heart isn’t affected directly???
Most important cause: neurally-mediated reflex syncope (NMS) (“fainting”, “vaso-vagal syncope”)
Secondary results due to vaso vagal syncope
Generally benign, but in elderly can result in head trauma due to sudden onset
Causes of circulating hypovolemia that can lead to neurally-mediated reflex syncope:
Dehydration, being hungover, standing at attention & locking knees for too long
Cause of syncope as related to the sympathetic nervous system
Exaggerated sympathetic activation (inappropriately excessive fight/flight response) can cause syncope
Describe Head Up Table Tilt
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!!
Relate a ventricular abnormality to syncope
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
Common symptoms prior to a cardiac related syncopal episode
often none prior to CV syncope (sudden lights out, or few seconds before fainting)
What symptoms suggest a neural mediation of syncope?
Nausea, sweating, abd discomfort, etc STRONGLY SUGGESTS NEURAL MEDIATION
_____ _____ seen in 94% (feel like having been hit by a truck after waking up)
Postdromal fatigue seen in 94% (feel like having been hit by a truck after waking up)
Exercise induced syncope suggests ______, but POST-exercise suggests _____.
Exercise induced syncope suggests CV, but POST-exercise suggests NMS
How is family history related to syncope?
Family history: member dying of inexplicable causes
Red Flags for Syncope
- high-risk occupations in general (if so, they need to be immediately relieved from their duties)
pilots, school bus drivers (sorry Ms Frizzle), etc
- elderly Pts are especially at a high risk for CV syncope b/c about ⅓ of them actually have it
Most dangerous medication for syncope
alpha-adrenergics mess up systemic vascular resistance
Most important vitals finding for syncope?
Vitals single most important (drop >20mmHg when orthostatic suggests intravascular depletion or autonomic dysfunction)
Relate murmurs to syncope
may be indicative of systolic ejection murmur due to aortic stenosis
confirm w/Valsalva and/or standing for hypertrophic cardiomyopathy
Relate CHF to syncope
general signs/symptoms of heart failure suggest high risk overall
When is echocardiography not helpful?
echocardiography is often helpful
useful for most patients -
EXCEPT FOR younger patients w/obvious NMS
Should we always do an EKG for syncopal patients?
99.999% of the time do an EKG to record new ischemia, old infarcts, long QT, LVH…
