Electrocardiogram Interpretation: A Brief Overview Wissam Alajaji, MD

Electrocardiogram Interpretation: A Brief Overview

Wissam Alajaji, MD

•Objectives:1. Basic principles for ECG interpretation2. Normal ECG3. Abnormal ECG examples

Know that This presentation will not cover “ECG dilemmas”Should you code Q wave in V1, V2 or only when it involves all V1, V2, V3.”A: only when V3 is involved“in LBBB should you code acute MI?”A: No

Wissam Alajaji, Electrocardiogram Interpretation: A Brief Overview, July-21, 2015.

13 slides


Basic principles for ECG interpretation• Before you look at the ECG:• Indication

- Muscle thickness, QT, arrhythmia- Chamber size and its complications- ischemia and its complications- electrolytes, drug toxicity

- 20 YO man with syncope- 50 YO man with acute chest pain- 65 YO woman with HTN and chronic SOB- 70 YO man with ESRD medications include digoxin, coming with altered level of consciousness


Basic principles for ECG interpretation

• Screen the ECG for quality:• Verify patients name, MRN, and date• Make sure that voltage is 10 mm/mv and calibrated• Screen for quality, correct lead placement, noise



Na, TCA

Ca Disturbance, DigoxinK Disturbance

Nothing is Random in

Life


Basic principles for ECG interpretation• Know how to calculate the HR, PR, QRS, and QT• Know what is a normal sinus morphology and identify abnormal• Know what is normal axis, normal voltage, normal vs pathologic Q,

juvenile patterns, normal variants


Nomenclature

Waves -P wave -T wave -U wave

Complex -QRS

Segments -PR segment -ST segment

Intervals -PR interval -QT interval

Point -J point

1 “little box” = 0.04 seconds (or 40 msec)

1 “big box” = 0.2 seconds (or 200 msec)• 5 “little boxes” = 1 “big box”• 5 “big boxes” = 1 second


• Step 1:• Locate RR interval: HR

• Step 2:• Rhythm & its origin

• Can be difficult and complex• Most common mistake made by

computer interpretation

For Boards

• Expected not to miss a serious/deadly finding/diagnosis• ST elevation• Hyperkalemia• Drug toxicity• Major pathology: heart block, arrhythmia, HCM……………………..

Usually, your indication is your guide

• Do not worry about controversial or minor findings


ECG Coding Sheet:



Unexpectedly "normal"

Inverted lead I in absence of Dextrocardia


Abnormally, normal avR

Rhythm


• So Far:

• You learned to ask about/present the indication before interpretation

• Scan for quality and lead placement

• Know the various electrical waves/intervals and what is normal ECG


Chamber Abnormality


24 year old man with syncope


45 year old man with HTN


LVH Criteria:

• The Cornell criteria:• R wave in aVL + S wave in V3 > 28 mm in males and > 20 mm in females of the

voltage criteria. • Therefore, the best policy is know most or all of the

• Sokolow:• S in V1 or 2+ R in V5 or V6 > 35 mV• R avL > 11 mV

• ST and/or T wave abnormalities, “strain” pattern



Codes:07 Sinus rhythm37 Right axis deviation (> +100 msec)41 Right ventricular hypertrophy43 RBBB, complete67 ST and/or T wave abnormalities secondary to hypertrophy


Chest pain/SOB



Codes:10 Sinus tachycardia43 RBBB, complete46 Left posterior fascicular block53 Anterior or anteroseptal Q wave MI (age recent or acute)57 Inferior Q wave MI (age recent or acute)65 ST and/or T wave abnormalities suggesting myocardial injury


Q1• Significant ST segment elevation consistent with myocardial injury or

infarction is defined by:• ≥ 1 mm STE in leads V1, V2, or V3• ≥ 2 mm STE in leads V1, V2, or V3• ≥ 2 in other leads• ≥ 1 in other leads


Q1• Significant ST segment elevation consistent with myocardial injury or

infarction is defined by:• ≥ 1 mm STE in leads V1, V2, or V3• ≥ 2 mm STE in leads V1, V2, or V3• ≥ 2 in other leads• ≥ 1 in other leads


Q2• Repolarization abnormality that suggest Acute or recent Myocardial

infarction include:• Peaked T waves followed by T wave inversion• ST elevation followed by peaked T waves• Deeply inverted T waves• Dominant R wave and ST depression in V1-V3


Q2• Repolarization abnormality that suggest Acute or recent Myocardial

infarction include:• Peaked T waves followed by T wave inversion• ST elevation followed by peaked T waves• Deeply inverted T waves• Dominant R wave and ST depression in V1-V3


Q3• Which parameter obtained on initial ECG independently predict 30 day all-cause

mortality in acute myocardial infarction:• Sinus tachycardia• Sum of absolute ST segment deviation elevation and or depression • QRS duration > 100 msec• Rightward axis deviation


Q3• Which parameter obtained on initial ECG independently predict 30 day all-cause

mortality in acute myocardial infarction:• Sinus tachycardia• Sum of absolute ST segment deviation elevation and or depression • QRS duration > 100 msec• Rightward axis deviation

Hathaway WR, et al. JAMA 1996, 273: 387-391.





Codes:06 Left atrial abnormality/enlargement10 Sinus tachycardia36 Left axis deviation (> –30o)47 LBBB, complete


Q1• A QRS duration ≥ seconds is necessary for the diagnosis of complete

LBBB:• 0.10• 0.11• 0.12• 0.13


Q1• A QRS duration ≥ seconds is necessary for the diagnosis of complete

LBBB:• 0.10• 0.11• 0.12• 0.13

When LBBB morphology is present and the QRS duration measures > 0.10 seconds but < 0.12 seconds, incomplete LBBB should be coded.


Q2• LBBB is commonly seen in normal hearts:

• True• False


Q2• LBBB is commonly seen in normal hearts:

• True• False

Never normal findingLBBB often occurs in various forms of organic heart disease, including ischemic and non-ischemic cardiomyopathy, valvular heart disease, LVH, and congenital heart disease. It is rarely seen in normal heartsShould not call it STEMIShould not call LVH: 80% patients with LBBB have abnormally increased LV mass


Bradycardia:

• A very big book in ECG

• Just on fun example


Codes:07 Sinus rhythm13 Atrial premature complexes


Tachycardia:



Codes:Sinus tachycardiaParoxysmal SVT


Killer

24 year old man with stressful life


Electrolyte/Drug toxicity:


65 year old man ESRD on dialysis presented with acute confusion Peaked T waves


17 year old female found by her room mate unconscious


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Electrocardiogram Interpretation: A Brief Overview Wissam Alajaji, MD