Before watching this week’s video, ask yourself this question:
- What do you consider to be the acceptable miss rate for deadly ECG findings?
Case 1: LBBB and AMI
Which patients with LBBB need emergent reperfusion therapy?
- Sgarbossa A & concordant STE = AMI
- Sgarbossa B & concordant STD in V1, V2, or V3 = AMI
- Revised Sgarbossa C & discordant ST segment > 25% size of R or S wave = AMI (pending validation study)
For more on this, review the case from June 1st, 2015
Case 2: Atrial Fibrillation with WPW
- Very rapid, irregularly irregular tachycardia
- Rates may approach 250-300 bpm or higher
- Variable QRS-complex shape and width
- Often misdiagnosed as SVT, VT, or A.fib with aberrancy
- AV nodal blockers (BB/CCB’s, Digoxin, Amiodarone, etc.) can cause V.fib & death
Avoid all AV nodal blockers in Atrial fibrillation with WPW!
Case 3: Septal STEMI vs Hyperkalemia?
ECG findings in Hyperkalemia
- Peaked T-waves
- Widening of the QRS (often marked)
- Prolonged PR-interval
- Flattening and eventual loss of P-waves
- Advanced AV Blocks and sinus pauses
- Fascicular & Bundle Branch Blocks
- Pseudo ACS with ST-segment changes (can mimic STEMI with focal STE!)
- Pseudo Brugada syndrome pattern
- Sine wave morphology
Beware…Hyperkalemia does whatever it wants to the ECG!
For more on hyperkalemia, review the case from Jan 12th, 2015
Case 4: Ventricular Tachycardia vs. AIVR
- Accelerated idioventricular rhythm (AIVR) is a relatively benign reperfusion arrhythmia
- It often occurs during reperfusion with thrombolytics after MI
- True ventricular tachycardia typically has a rate > 120 bpm
Case 5: Syncope & Anteroseptal ST-segment Depression
Differential for ST-depression in anteroseptal leads
- Anteroseptal ischemia
- Posterior STEMI
- Mirror image of septal STEMI in leads V1-V3
- Look for tall R waves, ST-depression, and upright T waves in V1-V3 on conventional 12 lead ECGs
- Even 0.5 mm of STE on posterior lead ECGs is diagnostic
ST-depression in the anteroseptal leads might represent posterior STEMI. Get posterior leads!
Case 6: Really Wide Complex Tachycardia
- When the QRS complex is really wide (> 1 big box or 200 ms) think of tox. and metabolic etiologies (ex. hyperkalemia and severe acidosis)
- Consider empiric treatment with Calcium & Sodium Bicarbonate!
For more about Na2+ channel blocker toxicity, review the case from Feb 23rd, 2015
Case 7: Bizarre Bradycardia
- Remember that hyperkalemia can also cause bizzare bradycardias and AV blocks
- When dealing with a bizarre rhythm that is not responding to ACLS therapy, consider empiric treatment for hyperkalemia!
Case 8: Low Voltage
Low Voltage Definition
- Specific Definition
- QRS amplitudes in limb leads all < 5 mm OR in all chest leads < 10mm
- Sensitive Definition
- QRS amplitudes in I+II+III < 15 mm OR V1+V2+V3 < 30 mm
Low Voltage QRS Differential
- “Low Power”
- Myxedema (severe hypothyroidism)
- Infiltrative diseases (Amyloid, Sarcoid, etc.)
- End stage cardiomyopathy
- Conduction blockage
- Fluid/Effusion (pericardial or pleural)
- Fat (obesity)
- Air (COPD)
New low voltage ECG + Tachycardia = Pericardial effusion until proven otherwise!
Avoid anticoagulants until pericardial effusion is ruled out.
For more, review the case from April 6th, 2015
Kudos: Congratulations to all the 2015 Emergency Medicine Residency Graduates!