ELECTROCARDIOGRAM (ECG)

Cardiovascular System Physiology Lab

Interpretation Dr.Mohammed Sharique Ahmed Quadri

Asst. professor in physiology

الرحيم الرحمن الله بسم

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 0.12 – 0.20 sec Is the PR interval constant ?

If prolong indicates various blocks

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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 3

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

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Variation in ST segment

ST ELEVATION

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

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ST ELEVATION SUGGESTIVE OF MI

ST ELEVATION (CONT)

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

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PUTTING IT ALL TOGETHERDo you think this person is having a myocardial infarction. If so, where?

Yes, this person is having an acute anterior wall myocardial infarction.

Now, where do you think this person is having a myocardial infarction?

Inferior wall MI

How about now?

Anterior & lateral wall MI

NORMAL

HYPERKALEMIA

HYPOKALEMIA

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INTERPRETE THE ECG ?

HYPERKALEMIA

Observe Tall T - wave15

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

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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

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Prof. Magdy El-Barbary

Prof. Magdy El-Barbary

Suggestive of

Question NO:

What is the most likely cause of changes in ST seg. & T wave of each diagram?

ECG CHANGES

Ways the ECG can change include:

Appearance of pathologic Q-waves

T-waves

peaked flattened inverted

ST elevation & depression

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