The document discusses the basics of electrocardiography (ECG), including that it records the electrical activity of the heart, not mechanical contractions. It explains that ECG waves are either positive or negative depending on if they represent depolarization or repolarization and their direction of travel. The document also outlines the electrodes and 12 leads used in ECGs, noting that multiple electrodes and leads allow views of the heart from different angles. Finally, it lists the waves seen on an ECG and what they represent in terms of atrial and ventricular activity.

3. the record of the electrical activity of the heart

4. BRAIN(EEG)

5. • Muscle (EMG)

6. The principle of ECG

9. • ECG does not record the mechanical
contraction of the heart

10. Normal ECG

11. Why some waves are
Positive and others are negative?
It depends on :
• the type of the wave (depolarization or
repolarization)
• the direction of the wave

12. Wave of depolarization

14. Wave of repolarizationWave of repolarization

15. Electrodes and Leads

16. Recording Electrodes9

17. 12 Leads

18. • Why many electrodes and leads?

23. leads
bipolar
1 2 3
unipolar
limb
a VR A VL A VF
chest
V1-V6

24. Bipolar leads

25. Bipolar leads

28. Unipolar limb leads

29. Unipolar chest leads

30. coronal transverse

33. The ECG WAVES

34. • Slow ventricular repolarization

35. • Atrial deplarization
• Conduction through AV node and AV
bundle

36. • Ventricular contaction

37. 1-ECG Interpretation Made Incredibly Easy! (5th
edition)
2-Clinical Physiology Made Ridiculously Simple
3-Guyton