How to Read an EKG

Always remember…1, 2, 3, get an old EKG!!!











Step 1: Identify the Rate and Rhythm











* Is it sinus rhythm?* P wave before every QRS* Is it one of the tachycardias? (Refer to THIS episode)* Is it one of the bradycardias? (Refer to THIS episode)











Step 2: Look for Signs of Ischemia











* Most consistent way is to examine by anatomic region of the heart* II, III, and aVF are “inferior” leads* I, aVL, V5, V6 are “lateral” leads* V1 and V2 are “septal” leads* V3 and V4 are “anterior” leads* Check for Q waves* Check for ST segment elevation or depression* Compare the J point with baseline (TP segment)* Check for peaked T waves and T wave inversions* T wave inversions in V1 and aVR are normal











Step 3: Look at Intervals











* PR interval* Wolf-Parkinson White Syndrome* 1st degree heart block* QRS interval* Left bundle branch block* Right bundle branch block* Sodium channel blockade* QT interval* Long QT syndrome* Hypokalemia* Risk of torsades de pointes











Step 4: Get an Old EKG











* If you find anything abnormal looking, compare to an old EKG











Bonus: Scarbossa Criteria











* Identifies ischemia in patients with a left bundle branch block* 1 lead with concordant ST elevation* 1 lead with concordant ST depression (V1-V3)* Severely discordant ST elevation (>25% preceding S wave)











Additional Reading











* Basic Approach to Tachycardias (EM Clerkship)* Basic Approach to Bradycardias (EM Clerkship)* EKGs for the Emergency Physician (Amazon)