READING ECGS SUMMARY By Dajour Collins Introduction This

READING ECGS (SUMMARY) By Dajour Collins

Introduction ◦ This is a summary ◦ Not going to include everything as that may be overwhelming ◦ Will focus on the essentials and establishing a method for reading (especially arrythmias)

Basics: Lead Placement (3 lead)

Basics: Lead Placement (12 lead)

Basics: Lead Placement (landmarks)

Basics: Lead Placement (12 lead)

Basics: Calibration ◦ The standard paper speed is 25 mm/sec: • 1 mm (small square) = 0. 04 sec (40 ms) • 5 mm (large square) = 0. 2 sec (200 ms) ◦ The standard Length of a strip is 10 seconds:

Basics: Calibration

Basics: ECG parts

Basics: Axis (Simple Method)

Basics: Rate & Rhythm At a paper speed of 25 mm/second • 1 SMALL square = 0. 04 seconds • 5 SMALL squares = 1 LARGE square = 0. 2 seconds • 5 LARGE squares = 1 second • ECG rhythm strip: • = 250 SMALL squares = 50 LARGE squares = 10 seconds • To calculate beats per minute (bpm): • 1500 SMALL squares = 300 LARGE squares = 1 minute • i. e. 250 x 6 = 1500 small squares = 1 minute of ECG Strip • and 50 x 6 = 300 large squares = 1 minute ECG strip

Basics: Rate & Rhythm (Methods) ◦ REGULAR rhythms • Rate = 300 / number of LARGE squares between consecutive R waves. ◦ Very FAST rhythms: • Rate = 1500 / number of SMALL squares between consecutive R waves. ◦ SLOW or IRREGULAR rhythms: • Rate = Number of R waves X 6 • The number of complexes (count R waves) on the rhythm strip gives the average rate over a ten-second period. This is multiplied by 6 (10 seconds x 6 = 1 minute) to give the average Beats per minute (bpm)

Basics: Rate & Rhythm (Methods)

Diagnostic Definitions: Right Atrial Hypertrophy ◦ Right Atrial Hypertrophy § P wave > 2. 5 mm in the inferior leads (II, III and AVF)

Diagnostic Definitions: Right Atrial Hypertrophy

Diagnostic Definitions: Left Atrial Hypertrophy ◦ Left Atrial Hypertrophy § Biphasic P wave with terminal negative portion > 40 ms duration § Biphasic P wave with terminal negative portion > 1 mm deep § i. e. Broad and Deep

Diagnostic Definitions: Left Atrial Hypertrophy

Diagnostic Definitions: Right ventricular Hypertrophy ◦ Diagnostic criteria • Right axis deviation of +110° or more. • Dominant R wave in V 1 (> 7 mm tall or R/S ratio > 1). • Dominant S wave in V 5 or V 6 (> 7 mm deep or R/S ratio < 1). • QRS duration < 120 ms (i. e. changes not due to RBBB)

Diagnostic Definitions: Right ventricular Hypertrophy

Diagnostic Definitions: Left Ventricular Hypertrophy • There are numerous criteria for diagnosing LVH • The most commonly used are the Sokolov-Lyon criteria o. S wave depth in V 1 + tallest R wave height in V 5 -V 6 > 35 mm • Easiest to remember (according to me) is the Modified Cornell Criteria o. R wave in a. VL >11 mm

Diagnostic Definitions: Left Ventricular Hypertrophy

Diagnostic Definitions: Bundle Branch Blocks (BBB) ◦ There are several diagnostic and associated features in diagnosing left vs right BB: But No need to get caught up in the specifics ◦ A widened QRS should raise your suspicion for a bundle branch block ◦ A simple way to diagnose/ differentiate RBBB VS LBBB is to check Lead V 1. ◦ If the QRS complex is widened and downwardly deflected/below baseline (QS wave) a LBBB is the most likely diagnosis. ◦ If the QRS complex is widened and upwardly deflected/above baseline (i. e. RSR' wave), it's a RBBB

Diagnostic Definitions: Right Bundle Branch Block

Diagnostic Definitions: Left Bundle Branch Block

BBB vs Accelerated Idioventricular ◦ BBB general has P and T waves ◦ Whereas AIs don’t usually have either (Though they may have P waves)

Arrhythmias: Anatomic Classification

Arrhythmias: Narrow Vs Wide QRS Complex ◦ A wide QRS Complex GENERALLY means that the Rhythm is originating from the ventricles ◦ A Narrow QRS Complex ALWAYS means the Rhythm is originating from above the ventricles (i. e. Sinus node, Atria or AV node)

Arrhythmias: The Importance of P waves ◦ P waves (or the lack thereof) are important in distinguishing arrythmias ◦ Important P wave Questions (in this order) ◦ How many P waves are there? ◦ Is there a regular relationship between the P waves and the QRS complex ◦ What is the morphology of the P waves

Arrhythmias: The Importance of P waves ◦ No P waves generally means the that the rhythm is either Junctional (AV node/prukinje) or Ventricular derived ◦ The exception to this is atrial fibrillation which also has no P waves but rather a rumbling of the baseline ◦ Atrial fibrillation is spot diagnosis however ◦ To Differentiate between Junctional and Ventricular in this instance (no P waves) just remember the Narrow vs Wide QRS complex rule i. e. ◦ If the QRS is wide (and no P waves) then it must be Ventricular ◦ Whereas if the QRS is narrow (and no P waves) then it is Junctional

Arrhythmia: Algorithm ◦ Rhythm: Regular Vs Irregular ◦ Rate: Fast Vs Slow Vs Normal ◦ QRS width: Wide Vs Narrow ◦ P wave: 3 important questions previously Outlined

Arrhythmia: Brady-arrythmia Algo ◦ If Consistently Wide (and slow) ◦ then the (ventricular) rhythm is originating in the ventricles ◦ So it is either 3 rd degree AV block or Idioventricular Rhythm (Ventricular Escape Rhythm due to some other cause) ◦ Differentiate Via P wave questions ◦ No P waves Idioventricular Rhythm ◦ P waves that have an irregular relationship to QRS complex 3 rd degree AV Block

Arrhythmia: Brady-arrythmia Algo ◦ If Consistently Narrow and (and slow) ◦ Then the rhythm must be originating ABOVE the ventricles ◦ So think sinus node pathology (e. g. Block) ◦ or Junctional (AV block, Junctional escape rhythm, Junctional Bradycardia) ◦ Differentiate via P wave questions ◦ No P wave= JER or JB ◦ P wave with specific pattern of AV blocks: AV block

Arrhythmia: Tachy-arrythmia Algo ◦ If QRS Consistently Wide (and Fast) ◦ Can Generally Assume V-Tach

Arrhythmia: Tachy-arrythmia Algo ◦ If Consistently Narrow (and fast), then use p wave number to differentiate as below ◦ If No P/T wave ◦ Then it must be A-fib or junctional tachycardia (e. g. AVNRT) ◦ differentiate based on regularity ◦ If one (1) P/T wave ◦ Assume junctional tachycardia (though it can be atrial flutter)

Arrhythmia: Tachy-arrythmia Algo ◦ If 3 P/T waves ◦ Assume Atrial flutter ◦ If 2 P/T waves ◦ Complicated ◦ Could be any of your regular or irregular SVTs ◦ Differentiate via regularity and other P wave questions

Arrhythmia: Normo-arrythmia Algo ◦ Normal Sinus Rhythm i. e. a non-arrhythmia +/- PAC, PJC and/or AV Block ◦ There are some arrythmias in this category but low yield for your exam (In my opinion) ◦ Accelerated idioventricular may be important

Method of reading ◦ CHROW PQRST (AH)

Arrhythmia: Application of Algorithms

Arrhythmia: Application of Algorithms ◦ Pulseless Electrical Activity (PEA): Left Blank on Purpose

Arrhythmia: Application of Algorithms

Arrhythmia: Application of Algorithms • Suspect atrial flutter with 2: 1 block whenever there is a regular narrow-complex tachycardia at 150 bpm — particularly when the rate is extremely consistent. • In contrast, the rate in sinus tachycardia typically varies slightly from beat to beat, while in AVNRT/AVRT the rate is usually faster (170 -250 bpm). • To tell the difference between these rhythms, try some vagal manoeuvres or give a test dose of adenosine — AVNRT/AVRT will often revert to sinus rhythm, whereas slowing of the ventricular rate will unmask the underlying atrial rhythm in sinus tachycardia or atrial flutter

Arrhythmia: Application of Algorithms

Spot Diagnosis

Other

Questions ◦ Where is the most common focus for atrial Fibrillation? ◦ Where is the most common focus for Atrial Flutter? ◦ Where are the locations of the Sino-atrial and AV Nodes? ◦ What are the Blood supply to SA and AV nodes? ◦ Which AV Blocks require treatment? ◦ What Rhythms are shockable vs Non-Shockable?