High Yield EKGs
Jason Ryan, MD, MPH
EKGs You Should Know
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Sinus rhythm
Atrial Fibrillation/Flutter
Ischemia: ST elevations, ST depressions
Left bundle branch block
Right bundle branch block
PAC/PVC
1st, 2nd, 3rd degree AV block
Ventricular tachycardia
Ventricular fibrillation/Torsades
Step 1: Find the p waves
• Are p waves present?
Sinus p waves
• Originate in sinus node
• Upright in leads II, III, F
Step 2: Regular or Irregular
• Distance between QRS complexes (R-R intervals)
Regular
Irregular
Steps 1 & 2
• P waves present, regular rhythm
• Sinus rhythm
• Rare: atrial tachycardia, atrial rhythm
• No p waves, irregular rhythm
• Atrial fibrillation – irregularly irregular
• Atrial flutter with variable block
Steps 1 & 2
• P waves present, irregular rhythm
• Sinus rhythm with PACs
• Multifocal atrial tachycardia
• Sinus with AV block
• No p waves, regular rhythm
• Hidden p waves: retrograde
• Supraventricular tachycardias (SVTs)
• Ventricular tachycardia
Step 3: Wide or narrow
• Narrow QRS (<120ms; 3 small boxes)
• His-Purkinje system works
• No bundle branch blocks present
• Wide QRS
• Most likely a bundle branch block
• Ventricular rhythm (i.e. tachycardia)
QRS Interval
Normal QRS
Right Bundle
Branch Block
Left Bundle
Branch Block
Step 4: Check the intervals
• PR (normal <210ms; ~5 small boxes; ~1 big box)
• Prolonged in AV block
• Lengthens with vagal tone, drugs
• Shortens with sympathetic tone
• QT (normal <1/2 R-R interval)
• Prolonged with ↓ Ca (tetany; numbness; spasms)
• Prolonged by antiarrhythmic drugs
• Shortened with ↑ Ca (confusion, constipation)
Step 5: ST segments
• T wave abnormalities
• Inverted: ischemia
• Peaked: Early ischemia, hyperkalemia (↑K)
• Flat/U waves: Hypokalemia (↓K)
• ST Depression
• Subendocardial ischemia
• ST Elevation
• Transmural ischemia
Normal Sinus Rhythm
Right Bundle Branch Block
Left Bundle Branch Block
Atrial Fibrillation
Atrial Flutter
Ventricular Tachycardia
Ventricular Tachycardia
Torsades de pointes
• ↑ risk with prolonged Qt interval
• Antiarrhythmic drugs
• Congenital long Qt syndrome
• Antibiotics (erythromycin, quiniolones)
• Hypokalemia
• Hypomagnesemia
• Rarely hypocalcemia
PAC and PVC