emergency lectures - ecg review india2005
TRANSCRIPT
How to Interpret ECG: The Basics
Heather A. Crane, M.D.
Attending Physician, Emergency Department
Loma Linda University Medical Center
Goals
Review a systematic approach to ECGs Review the major rhythms Review ischemia and infarct Treatment for various rhythms and ACS
What does the ECG represent?
Vectors of electricity It shows us:
– Rhythm disturbances– Conduction disturbances– Reflects electrolyte status– Reveals damage to myocardium
What does the ECG represent?
Vectors of electricity It shows us:
– Rhythm disturbances– Conduction disturbances– Reflects electrolyte status– Reveals damage to myocardium
How good is the ECG?
It is very specific However, it is not the most sensitive tool,
particularly when ruling out infarct or ischemia
Where do the leads go?
There are limb leads: I, II, III, AVR, AVL, AVF There are precordial leads: V1-V6
Assessing EKGs: The Conduction System
Bachmann’s bundle
Left bundle branch
Posterior division
Anterior division
Purkinje fibersRight bundle branch
Bundle of His
AV node
Internodal pathways
Sinus node
Relationship of the ECG to Anatomy
The picture is too big for this slide
The waves and the intervals
P-wave: represents atrial contraction QRS: represents ventricular contraction T-wave: represents repolarization PR interval: represents the AV node QT interval: ventricular depolarization and
repolarization
The waves and the intervals
P-wave is <.10 seconds wide PR interval is .12-.20 seconds QRS is .06-.10 seconds wide QT is .33-.42 seconds (varies with age and
gender) T-wave should be upright in all leads except
AVR and sometimes III
Determining the Rate
Analyzing the Rhythm
Key questions– Is the rhythm regular or irregular?– Is it fast ( >100) or slow (<60)?– Are QRS complexes and P waves present?– How is the P wave related to the
QRS complex?– Is the QRS complex wide or narrow?– What are the intervals (PR, QT, PP, RR)?
Axis
Is the patients heart enlarged? We look at leads I and Avf to determine axis. The QRS complex should be upright in both. If it is up in Avf and down in I, this is right axis
deviation. If it is down in Avf and up in I, this is left axis
deviation.
Injury, Ischemia, Infarct
Baseline
Ischemia—tall or inverted T wave (infarct),ST segment may be depressed (angina)
Injury—elevated ST segment, T wave may invert
Infarction (Acute)—abnormal Q wave,ST segment may be elevated and T wavemay be inverted
Infarction (Age Unknown)—abnormal Q wave,ST segment and T wave returned to normal
How to approach the ECG
Very Carefully Think: Rate, Rhythm, Axis, Injury, Ischemia,
Infarct This way you don’t overlook things and you
can make sense of even the most chaotic looking ECGs
ECG 1
ECG 2
Comparison ECG
ECG 3
ECG 4
ECG 5
ECG 6
ECG 7
ECG 8
ECG 9
ECG 10
ECG 11
Compare this with ECG 11
Acute MI Localization
aVF inferiorIII inferior V3 anterior V6 lateral
aVL lateralII inferior V2 septal V5 lateral
aVRI lateral V1 septal V4 anterior
ECG 12
ECG 13
ECG 14
ECG 15
ECG 16
ECG 17
ECG 18
ECG 19
ECG 20