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

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.

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

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

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

Variation in ST segment

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

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.

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.

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

INTERPRETE THE ECG ? HYPERKALEMIA Observe Tall T - wave

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

Prof. Magdy El-Barbary

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

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

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