Emergency Medicine is Hard

Differential for Narrow Complex Regular Tachycardia

• Sinus tachycardia
• Supra-ventricular tachycardia – look for retrograde P-waves
• Aflutter with 2:1 atrioventricular conduction

Differential for Narrow Complex, Irregularly Irregular Tachycardia

• Atrial fibrillation
• Atrial flutter
• Multi-focal atrial tachycardia (MAT)

Differential for Wide Complex Irregular Tachycardia

• Atrial fibrillation with bundle branch block
• Atrial fibrillation with WPW

Differential for Wide Complex Regular Tachycardia

• Ventricular tachycardia
• ST with aberrancy
• SVT with aberrancy

Differential diagnosis for prolonged QT interval

• Electrolytes – hypokalemia, hypomagnesemia, hypocalcemia
• Acute MI
• Elevated intracranial pressures
• Drugs with sodium blocking effects
• Hypothermia
• Congenital prolonged QT syndromes

Differential for diffuse ST Elevations

• Large acute MI
• Pericarditis
• Benign early repolarization
• LVH

Causes for a Leftward Axis

• LBBB
• Prior inferior wall MI
• Left anterior fascicular block (LAFB)
• Ventricular ectopy
• Paced beats
• LVH
• WPW Syndrome

Causes for a Rightward Axis

• Right ventricular hypertrophy
• Lateral MI (if large Q waves are present)
• Acute (e.g. PE) or chronic (e.g. COPD) lung disease
• Ventricular ectopy (e.g. VTach)
• Hyperkalemia
• Sodium-channel blocking drug toxicity (e.g. TCAs)
• Left posterior fascicular block
• Misplaced leads (lol…)

Remembering Wellens’ is the bane of my existence

• ECG T-wave abnormalities in leads V2-V4
  • Type 1: Deep inverted T-waves
  • Type 2: Biphasic T-waves
• High risk for extensive anterior wall MI within 2-3 weeks
• Presentation: Chest pain free, no ST segment changes, normal cardiac markers at presentation

ST-Elevation in AVR and why you should care

• STE in lead AVR is highly suggestive of left-main coronary artery (LMCA) occlusion, which has a 70% mortality without prompt invasive therapy ; medical management alone is ineffective
• When the STE in lead AVR is greater than the STE in lead V1, or when there is simultaneous STE in leads AVR and AVL, the specificity for LMCA occlusion increases

Diagnostic Criteria for LBBB

• QRS > 120ms
• Broad monophasic R-wave in lateral leads (I, V5, V6)
• rS complex in the right precordial leads

Diagnostic Criteria for LVH

• (S-wave in V1) + (R-wave in V6) > 35mm
• “LVH strain pattern” – LVH is often associated with T-wave inversions in lateral leads (Leads I, AVL, V5, V6) due to abnormal ventricular repolarization; this abnormality does not represent acute MI

Things I didn’t know about WPW

• Wide QRS complexes are the result of atrial conduction through the accessory pathway

How many PVCs is too many?

• Ventricular Tachycardia – Three or more consecutive PVCs; typically >120 bpm
• Non-sustained V-Tach – VT lasting less than 30 seconds AND is not associated with hemodynamic compromise
• Sustained V-Tach – VT >30s; may be associated with hemodynamic compromise

Bru(Gawd)a Syndrome

• Can lead to sudden onset monomorphic or polymorphic ventricular tachycardia
• ECG findings:
  • Incomplete/complete RBBB
  • Type 1: Coved ST segment elevation >2mm in >1 of V1-V3 followed by a negative T wave
  • Type 2: Saddle-back STE >2mm
• Definitive treatment: ICD placement

Poor R Wave Progression

• Defined as a R-wave amplitude <3mm in lead V3
• Lots of possible causes, but may be suggestive of an old anteroseptal MI

Inferior STEMI with right ventricular involvement

• The magnitude of the ST-elevation in lead III is GREATER than the ST-elevation in lead II

Regular Irregular Rhythms

• Second degree AV blocks
• Ectopic beats that occur regularly (e.g. bigeminy, trigeminy)