1. ECG The Basics And Beyond
Anita Ralstin MS, FNP-BC

2. I have no conflicts of interest.

3. Pearls Treat the patient not the paper.
Electrical activity triggers mechanical activity. No electrical activity = no mechanical activity
But electrical activity does not guarantee mechanical activity.
The more cells involved the larger the deflection on the ECG.
If the wave of electrical activity is moving toward the electrode, the wave will be positive (above the baseline); if the wave is moving away from the electrode the wave will be negative (below the baseline).

4. Cardiac Conduction System
normal ECG
One small box = .04 seconds
One large box = .20 seconds
Conduction picture courtesy of New Mexico Heart Institute

5. Anatomy and the ECG
The P wave = atrial activation (SA node to AV node).
The PR interval = onset of atrial activation to onset of ventricular activation.
The QRS complex = electrical ventricular activation.
The ST-T segment = ventricular repolarization.
The QT interval = the duration of ventricular activation and recovery.

6. Calculation Of Heart Rate
Method 1: Count the number of large (0.2-second) time boxes between two successive R waves, and divide the constant 300 by this number OR divide the constant 1500 by the number of small (0.04-second) time boxes between two successive R waves.
Method 2 best for irregular rhythms: Count the number of cardiac cycles that occur every 6 seconds, and multiply this number by 10.

7. The Rule Of 300 It may be easiest to memorize the following table:
# of big boxes
Rate 1
300 2
150 3
100 4 75 5 60 6 50

8. Calculation Of Heart Rate

9. Question
Calculate the heart rate

10. Definition of Normal Sinus Rhythm
Heart rate
Adult
Infant
Toddler
year old
Regular rhythm
P waves round, same shape and before each QRS
Normal PR interval ( sec or 3-5 small boxes)
Normal QRS interval (< 0.12 sec or < 3 small boxes)
QRS positive in leads I, II, aVF, V3-V6

11. Cardiac Conduction System
normal ECG
Conduction picture courtesy of New Mexico Heart Institute

12. Where Does The Impulse Come From?
Electrical Impulse
Formation
Initiation Point
Rate
Regularity
Onset
SA Node, Atrial, Junction, Ventricles
Normal, Tachycardic, Bradycardic
Regular, Irregular, Irregularly irregular
Passive escape, active

13. Where/How Does The Impulse Travel?
I, II, III
RBBB
Electrical Impulse
Conduction
Sinus Node
Atria
AV Junction
Ventricular
SA Block
Intra Atrial Block
LBBB
LAH, LPH
Complete, Incomplete

14. Combined Flow Sheet Initiation Point Formation Rate Regularity Onset
I, II, III
RBBB
Conduction
Sinus Node
Atria
AV Junction
Ventricular
SA Block
Intra Atrial Block
LBBB
LAH, LPH
Complete, Incomplete
Electrical Impulse
Formation
Initiation Point
Rate
Regularity
Onset
SA Node, Atrial, Junction, Ventricles
Normal, Tachycardic, Bradycardic
Regular, Irregular, Irregularly irregular
Passive escape, active

15. Sinus Rhythm The P wave is upright in leads I and II
Each P wave is usually followed by a Q
The heart rate is 60­-100 beats/min

16. When Is The Rhythm Unstable
Four main signs
Signs of low cardiac output – systolic hypotension < 90 mmHg, altered mental status
Excessive rates: <40/min or >150/min
Chest pain
Heart failure
If unstable, electrical therapy: cardioversion for tachyarrhythmia, pacing for bradyarrhythmia

17. Review Of Common Rhythms
1. Normal Sinus Rhythm 2.

18. Review Of Common Rhythms
3. 4. Supraventricular Tachycardia

19. Review Of Common Rhythms
4. 6. Atrial Flutter 5.

20. Review Of Common Rhythms
nd Degree AV Block Type 1 (Wenckebach)

21. Cardiac Conduction System
normal ECG
Conduction picture courtesy of New Mexico Heart Institute

22. Review Of Common Rhythms

23. Cardiac Conduction System
normal ECG
Conduction picture courtesy of New Mexico Heart Institute

24. Review Of Common Rhythms9.

25. Review Of Common Rhythms
10.

26. Review Of Common Rhythms

27. Cardiac Conduction System
normal ECG
Conduction picture courtesy of New Mexico Heart Institute

28. Thank you
Questions?