Electrocardiogram interpretation

Cardiac conduction system
12 lead system
rules for normal ECG.
Determination of heart rate

1. Interpretation of Electrocardiogram (ECG) Dr.Nidhi Ahya(Asst Prof) Cardio-Vascular & Respiratory PT DVVPF College of Physiotherapy, Ahmednagar 414111

2. Objectives Cardiac conduction system 12 lead system rules for normal ECG. Determination of heart rate.

3. Lead Systems- 12 lead ECG Bipolar Limb Leads -3 Precordial Chest Leads-6 Augmented Leads-3

4. Anatomic Groups

5. Determine regularity Look at the R-R distances Regular -are they equidistant apart? Occasionally irregular? Regularly irregular? Irregularly irregular? R R

6. The 10 rules for a normal ECG

7. Rule 1 PR interval Millivolts Milliseconds 200 400 600 -0.5 0.5 1.0 P R T Q S PR interval should be 120 to 200 milliseconds (0.12-0.2 sec) or 3 to 5 little squares

8. Rule 2 Millivolts Milliseconds 200 400 600 -0.5 0.5 1.0 QRS P R T Q S The width of the QRS complex should not exceed 110 ms, less than 3 little squares

9. Rule 3 I II III aVR aVL aVF The QRS complex should be dominantly upright in leads I and II

10. Rule 4 I II III aVR aVL aVF QRS and T waves tend to have the same general direction in the limb leads

11. Rule 5 P Q T S All waves are negative in lead aVR

12. Rule 6 V 1 V 2 V 3 V 4 V 5 V 6 The R wave in the precordial leads must grow from V1 to at least V4

13. I II III aVR aVL aVF V1 V2 V3 V4 V5 V6 Rule 7 The ST segment should start isoelectric except in V1 and V2 where it may be elevated

14. Rule 8 I II III aVR aVL aVF V1 V2 V3 V4 V5 V6 The P waves should be upright in I, II, and V2 to V6

15. Rule 9 I II III aVR aVL aVF V1 V2 V3 V4 V5 V6 There should be no Q wave or only a small q less than 0.04 seconds in width in I, II, V2 to V6

16. Rule 10 I II III aVR aVL aVF V1 V2 V3 V4 V5 V6 The T wave must be upright in I, II, V2 to V6

17. Determination of Heart Rate

18. Grid Methods – Regular rhythms 1500/ No.of small squares between 2 consecutive R 300/ No.of large squares between 2 consecutive R

19. Scan Method - irregular Check for 3 sec/ 6 sec markers Count the number of QRS complexes between markers Multiply by 20 / 10 for 3 & 6 sec markers respectively

20. Decreased Automaticity Sinus Bradycardia

21. Increased/Abnormal Automaticity Sinus tachycardia

22. Normal Sinus Rhythm ECG Characteristics: Regular narrow-complex rhythm Rate 60-100 bpm Each QRS complex is proceeded by a P wave P wave is upright in lead II & downgoing in lead aVR

23. Sinus Bradycardia HR< 60 bpm; Every QRS narrow, preceded by p wave Normal in well-conditioned athletes HR can be<30 bpm in children, young adults during sleep, with up to 2 sec pauses

24. Sinus tachycardia HR > 100 bpm, regular Often difficult to distinguish P and T waves

25. Sinus Arrhythmia Variations in the cycle lengths between P waves/ QRS complexes Will often look irregular on exam Normal P waves, PR interval, normal, narrow QRS

26. Atrial Fibrillation Caused by a large reentrant circuit in the wall of the right atrium Caused by numerous wavelets of depolarization spreading throughout the atria simultaneously, leading to an absence of coordinated atrial contraction.

27. Ventricular tachycardia Ventricular tachycardia is usually caused by reentry, and most commonly seen in patients following myocardial infarction

28. Ventricular fibrillation

29. Summary What is cardiac conductive system. 12 leads of ECG. Rules for normal ECG Determination of heart rate.

30. QUESTIONS WHAT ARE THE RULES OF NORMAL ECG? 5MARKS DESCRIBE THE 12 LEADS OF ECG. 5MARKS

31. Thank you