1. ECG interpretation
Dr mahesh batra
Pg adult cardiology
Nicvd

2. Objectives Justify the reasons for performing an ECG
Develop a structured approach to interpreting an ECG
Practice interpreting ECGs

3. The ECG
“The ECG (electrocardiogram) is a transthoracic interpretation of the electrical activity of the heart.”

4. 21 yo presents for routine physical exam
DEXTROCARDIA

5. Rate: 38 bpm
Rhythm: Regular
P Waves: Normal
PR Interval: 0.16 sec
QRS: 0.10 sec
Interpretation: Sinus bradycardia

6. Rate: 136 bpm
Rhythm: Regular
P Waves: Normal but encroach on preceding T waves
PR Interval: 0.12 sec
QRS: 0.08 sec
Interpretation: Sinus tachycardia

7. Rate: 90 bpm (counting PVCs), 75 bpm in now
underlying rhythm
Rhythm: Irregular
P Waves: Normal
PR Interval: 0.16 sec
QRS: 0.10 sec
Interpretation: Normal sinus rhythm with two multiform
PVCs with noncompensatory pauses

8. Rate: 60 bpm
Rhythm: Irregular
P Waves: Normal
PR Interval: Progressive prolongation until
dropped QRS
QRS: 0.10 sec
Interpretation: Second-degree AV block Type I
(Wenckebach

9. Why perform an ECG? Indicated by the patient’s symptoms
- symptoms of IHD/MI
- symptoms associated with dysrhythmias
Indicated by the patient’s examination findings
- cardiac murmur

10. ECG interpretation Quality of ECG? Rate Rhythm Axis P wave PR interval
QRS duration
QRS morphology
Abnormal Q waves
ST segment
T wave
QT interval
It’s vital to have a system in place to interpret the ECG.

11. Intervals
Small box large box

13. Quality of the ECG Patient name Date of the ECG
Is there any interference?
Is there electrical activity from all 12 leads?
Calibration:
- speed = 25mm/second
- height = 1cm/mV
Small square 0.04s; Large square 0.2s

14. Calibration

15. ECG interpretation Quality of ECG? Rate Rhythm Axis P wave PR interval
QRS duration
QRS morphology
Abnormal Q waves
ST segment
T wave
QT interval
It’s vital to have a system in place to interpret the ECG.

16. Rate
Rule of 300- Divide 300 by the number of boxes between each QRS = rate
Rate is either:
- normal
- bradycardic
- tachycardic
Number of big boxes
Rate 1
300 2
150 3
100 4 75 5 60 6 50

17. Rate – How can you count it?
Count off "300, 150, 100" for every thick line that follows the start line, naming each line as shown. Know these numbers
Then: Count off the next three lines after "300, 150, 100" as "75, 60, 50.“
Should only use with regular rhythms

18. Rate AF

19. Rhythm
Sinus
Not sinus
Morphology
Supravent.
Ventricular

20. Heart Rhythms, Let’s Keep It Simple!
Steps to Rhythm Interpretation:
Is it regular or irregular?
What is the rate
(too slow or too fast)?
Is there a P for every QRS?
Is there a QRS for every P?
What is the P-R interval?
Is the R to R interval regular?
What is the QRS duration
(QRS wide or narrow)?

21. Mechanisms of Arrhythmogenesis
Disorder of impulse formation.
Automaticity.
Triggered Activity.
Early after depolarization.
Delayed after depolarization.
Disorder of impulse conduction.
Block
Reentry.
Combined disorder.
It may be clinically difficult to separate.
Some tachyarrhythmias can be started by one mechanism and perpetuated by another. For example, an initiating tachycardia or premature complex caused by abnormal automaticity can precipitate an episode of tachycardia sustained by reentry.

22. Normal Sinus Rhythm
Originates in the SA node, follows appropriate conduction pathways.
Rhythm: Regular
Rate: bpm
Every P has a QRS and every QRS has a P
PRI: seconds
QRS: seconds, narrow

23. Is the Rhythm Regular? R to R interval should be Regular

24. Interesting, right?
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