1. ELECTROCARDIOGRAM (ECG)
بسم الله الرحمن الرحيم
Cardiovascular System Physiology Lab
Interpretation
Dr.Mohammed Sharique Ahmed Quadri
Asst. professor in physiology
ELECTROCARDIOGRAM (ECG)

2. objective
Analyze the ECG and calculate the heart rate and cardiac axis.
Know the importance of ST segment in IHD and MI.
Apply knowledge of analyzing ECG on interpretation of sinus tachycardia, sinus bradycardia, AF, IHD, MI, heart block.

3. Analyzing individual waves & segments
P wave : upright except in avR
Normal duration: 0.08 to 0.11 sec
do you see p waves ?
are all p waves same ?
does all QRS complexes have p waves ?
P-R interval : Normal range – 0.20 sec
Is the PR interval constant ?
If prolong indicates various blocks

4. Analyzing individual waves & segments
QRS complexes:
Are the p waves & QRS complexes are associates with each other
Are the QRS complexes narrow or wide
ST Segment :
Normal : Isoelectric
Elevation : in acute MI
Depression : in ischemia
T wave:
Tall T wave : ischemia, hyperkalemia
Inverted : young children ,deep inspiration, bundle branch block, ischemia,hypokalemia

5. Analyzing individual waves & segments
QT INTERVAL:
0.4 to 0.43 seconds depending upon heart rate.
At high heart rates, ventricular action potentials shorten in duration, which decreases the Q-T interval.
. prolonged in acute MI ,hypocalcaemia

6. Variation in ST segment

7. ST Elevation
One way to diagnose an acute MI is to look for elevation of the ST segment.

8. ST Elevation suggestive of MI

9. ST Elevation (cont)
Elevation of the ST segment (greater than 1 small box) in 2 leads is consistent with a myocardial infarction.

11. Putting it all Together
Do you think this person is having a myocardial infarction. If so, where?
Yes, this person is having an acute anterior wall myocardial infarction.

12. Now, where do you think this person is having a myocardial infarction?
Inferior wall MI

13. How about now?
Anterior & lateral wall MI

14. NORMAL
HYPERKALEMIA
HYPOKALEMIA

16. INTERPRETE THE ECG ?
HYPERKALEMIA
Observe Tall T - wave

17. Reporting of ECG This ecg shows Sinus rhythm Heart rate of 75/ min
Normal QRS axis
Normal PR interval 0.12 sec
Normal QRS duration 0.8 sec
ST segment isoelectric in all leads
T wave normal & upright in all wave except in aVR

18. Prof. Magdy El-Barbary

20. Prof. Magdy El-Barbary
Question NO:
Suggestive of
What is the most likely cause of changes in ST seg. & T wave of each diagram?

21. ECG Changes Ways the ECG can change include: ST elevation & depression
Appearance of pathologic Q-waves
T-waves
peaked flattened inverted

22. References
Text book of medical physiology by GUYTON & HALL 11 th edition
Text book physiology by GANONG
The ECG made Easy by John R.Hampton sixth edition
The guide to EKGinterpretation by JohnA.Brose, D.O,John C.Auseon