1. The Electrocardiogram Charles E. Wood, Ph.D.

2. Willem Einthoven receives Nobel Prize The EKG is not only the oldest but, in fact, over 100 years after its introduction, continues as the most commonly used cardiovascular laboratory procedure.

3. Resting membrane potential The Nernst Equation: E K = -61.5  log (K i /K o ) [K + ] i =135 mEq/L - - - - ++++

4. Cellular Action Potentials

5. Spread of the Action Potential

6. Instantaneous potentials developed on the surface of a cardiac muscle mass. Figure 11-4. Copyright 2000, WB Saunders Company, All Rights Reserved

7. Recording depolarization and repolarization waves Zero voltage - Isoelectric point Resting stage - Polarized

8. Flow of current in the chest around partially depolarized ventricles. Figure 11-5. Copyright 2000, WB Saunders Company, All Rights Reserved

9. The Wave of Depolarization

10. ECG and Mechanics

11. Vector Algebraic Analysis

12. Vector Analysis, cont’d

13. Summary of Limb Leads

14. The Precordial (Chest) Leads

15. Vector Algebraic Analysis

16. Vector Analysis, cont’d

17. Current Flow Patterns Sinoatrial Node Atrioventricular Node

18. Time relationships between developed force and the changes in transmembrane potentials in a thin strip of ventricular muscle Mechanical event Electrical event Time

19. ECG and Mechanics

20. Modulation of the Slow-Response (Nodal) Action Potentials

21. The Wave of Depolarization

24. Sinus rhythm

25. Sinus bradycardia (lead III). Figure 13-2. Copyright 2000, WB Saunders Company, All Rights Reserved Menu F B

26. Prolonged P-R interval caused by first degree heart block (lead II) Figure 13-5. Copyright 2000, WB Saunders Company, All Rights Reserved Menu F B

27. Mobitz type II AV block

28. Complete AV block

29. Sinus tachycardia (lead I) Figure 13-1. Copyright 2000, WB Saunders Company, All Rights Reserved Menu F

30. Atrial tachycardia with 2:1 conduction

31. Ventricular preexcitation (WPW)

32. Tachycardia circuits in Wolff-Parkinson-White syndrome