CRACKCast E015 – Syncope

In CRACKCast, Featured, Podcast by Adam Thomas1 Comment

This episode of CRACKCast covers Rosen’s Chapter 15, Syncope. This short but high yield chapter covers Syncope, a common reason for emergency visits that may be benign, but sometimes can have more sinister diagnoses lurking that cannot be missed!

Shownotes – PDF Link


Rosen’s in Perspective:

Syncope is defined as a sudden, transient, loss of consciousness with loss of postural tone accompanied by a rapid return to baseline.

  • prevalence: 1 in 5 in life-time
  • wide range of life threatening to totally benign causes
  • patients with known CAD who have a syncope from any cause have highest mortality
  • risk factors: known cerebral vascular disease/HTN/cardiac medications
  • increase mortality associated with age, CHF, CAD
  • no mortality from vasovagal, orthostatic, or medication induced syncope unless patient suffers trauma/injury


Bilateral hemispheric dysfunction or Reticular Activating System (RAS) dysfunction

  • majority from acute hypo-perfusion
  • can be local (cerebral vasoconstriction (SAH) or systemic hypovolemia (diarrhea))

Pre-syncope and syncope are the same entity! On a spectrum from pre-syncope, syncope, to coma.


1) What are 12 critical causes of syncope

When cerebral perfusion pressure drops more than 35% the patient may have syncope






Critical causes of syncope:

  • MI
  • arrhythmia
  • thoracic aortic dissection
  • critical Aortic Stenosis
  • HOCM
  • pericardial tampondade
  • abdominal aortic aneurysm
  • PE
  • subarachnoid bleed
  • toxin mediated
  • severe hypovolemic shock
  • ruptured ectopic pregnancy

Other causes of syncope:

Box 15-1. Causes of syncope. Rosen’s 8th Edition. Chapter 15 – page 136.




2) List common medications that can cause syncope

Cardiac meds – can cause hypotension

QT prolonging medications – can lead to transient Torsade de Pointe


Insulin/oral hypoglycemic agents

Recreational Drugs

Box 15-2. Rosen’s 8th edition. Chapter 15 – page 137.



3) Describe the San Francisco Syncope Rule

5 points:

  1. History CHF
  2. Hematocrit <30%
  3. Abnormal ECG
  4. SOB on history
  5. SBP <90 at triage

4) What are red flags that require admission in syncope?


  • chest pain
  • unexplained SOB
  • a hx of significant CHF or valvular disease
  • patient with ECG evidence of ventricular dysrhythmias, ischemia, significantly prolonged QT intervals, or new BBB

Relative red flags (consider admission):

  • age > 45
  • pre-existing cardiovascular or congenital heart disease
  • family history of sudden death (Brugada)
  • serious comorbidities such as diabetes
  • exertional syncope (HOCM, critical AS)

This post was edited and uploaded by Ross Prager (@ross_prager)

Adam Thomas

CRACKCast Co-founder and newly minted FRCPC emergency physician from the University of British Columbia. Currently spending his days between a fellowship in critical care and making sure his toddler survives past age 5.

Tristan Jones

Tristan Jones is a resident by day, early 90s style hacker by night. We had to give this Emergency Medicine Resident from UBC a job, or else he would shut down our website faster than Anonymous taking down Donald Trump.