This document provides an overview of rhythm recognition and interpretation from an electrocardiogram (ECG). It defines common ECG components like the P wave, QRS complex, and T wave. It identifies normal sinus rhythm and discusses other rhythms like sinus bradycardia, sinus tachycardia, premature ventricular contractions, ventricular fibrillation, ventricular tachycardia, and asystole. The document provides guidance on lead placement, intervals, and measuring heart rate from an ECG. It emphasizes the importance of maintaining patient dignity and monitoring vital signs in addition to the ECG.

1. Rhythm Recognition
(Interpretation)
Des Wade
MSc; Advanced Paramedic

2. Objectives
 Identify P,QRS,T waveforms on a normal ECG.
 Identify at least the following rhythms:
 Normal sinus rhythm (N.S.R)
 Sinus Bradycardia
 Sinus Tachycardia
 N.S.R with premature ventricular contractions
 Ventricular Fibrillation
 Ventricular Tachycardia
 Asystole

3. Electrocardiogram
ECG (Electrocardiogram) is a written record of the
electrical activity of the heart

4. Who should be
monitored?
 All unconc. Patients
 All chest pain patients
 All trauma patients
 Known cardiac patients
 All breathless patients
 Patients complaining of light-
headedness/dizziness
 Patients with abnormally fast or slow pulses
 When a doctor requests monitoring

5. Chest Preparation
 Explain what you are about to do
 Expose the monitoring area
 Select and prepare the electrode site by wiping
down the skin and drying it, if necessary

6. Chest Preparation
• Shave hairy chests with razor/clippers?
• Prepare skin with “prep tape" or wipes?
• Attach leads to electrodes before placing them on
the patient's chest
• Apply electrodes in the correct position making sure
they adhere well
• Record E.C.G.

7. Issues Effecting
Monitoring
 Sweating, moist skin
 Oily, dirty or scaly skin
 Excessive chest hair
 Dried conductive gel
 Patient movement, muscle tremor
 Interference from electrical
apparatus/Mobile phones
 Faulty equipment, low battery state
 Clinical intervention

8. ARTIFACTS
Present as bizarre recordings
They can be caused by a
number of factors, eg: patient
movement.

9. Lead Placement
R
Y
GN
Ride
Your
Green
Nelly
Patients’
Right
Patients’
Left

10. So what do the 3 leads see?
 Monitoring
 Typically Lead II
 Inferior wall of the myocardium

11. INFERIOR
WALL
Inferior Wall

12. The ECG paper….Time.
 25mm per second
 1 Small Square = 0.04 Seconds.
 5 Small Squares = 0.2 Seconds.
 1 Large Square = 0.2 Seconds.
 5 Large Squares = 1 Second.

13. The ECG paper….Time.
= 0.04 Second x 5 = 1 second
= 0.2 Second

14. Electrical Conduction System

15. Normal Sinus Rhythm
Main pacemaker
SA Node

16. The Electrocardiogram ECG
 P Wave
 represents
depolarisation
(electrical activity)
of the atria
 is usually followed
by contraction of
the atria

17. The Electrocardiogram ECG
PR Interval
 Depolarisation of the
Atria and the delay at
the AV Junction
 PR Interval
 0.12 - 0.20 seconds =
3 - 5 small squares

18. The Electrocardiogram ECG
QRS Complex
 represents
depolarisation
(electrical activity) of
the ventricles
 is usually followed by
contraction of the
ventricles
 QRS duration
 0.08 - 0.12 seconds =
2 - 3 small squares

19. The Electrocardiogram ECG
T Wave
 represents repolarisaton of
the ventricles
 or relaxation of the ventricles

20. The Electrocardiogram ECG
P Wave
 Depolarisation of
the atria
QRS Complex
 Depolarisation of
the ventricles
T Wave
 represents
Repolarisation of
the ventricles

21. IDENTIFYING RHYTHMS
P Waves ?
 Before every QRS ?
PR Interval
 .12 - .2 sec ?
QRS Complex ?
 Width < .12 sec ?
 Rate ?
 Rhythm ?
 Origin

22. ECG Intervals
 R - R Interval
• Distance between each QRS
Complex
 QS Complex
• Is when the entire complex is
negatively deflected
• Considered equivalent to a
wide Q wave
 Horizontal Axis
• Small box 0.04 sec
• Large box 0.2 sec
• 5 Large boxes 1 second
 Vertical Axis
• Small box 0.1 mV
 PR Interval
• 0.12 to 0.2 sec
 QRS Complex
• < 0.12 sec

23. ECG Intervals

24. Normal
 PR Interval 0.12 - 0.20 seconds = 3 - 5 small
squares
 QRS duration 0.08 - 0.12 seconds = 2 - 3 small
squares

25. Measuring the Rhythm
 Ventricular Rate
• Triplicate method
– 300 – 150 – 100 – 75 – 60 -
50
• R-R method
– divide 300 by # of large
squares between
consecutive R waves
• 6 Second method
– multiply # of R waves in a
6 second strip by 10
• Rate meter unreliable!!!

26. Inherent Rates
1 SA Node
 60-100
2 AV Junction
 40-60
3 Ventricles
 20-40
1
2
3

27. PR Interval 0.12 - 0.20 seconds = 3 - 5 small
squares
QRS duration 0.08 - 0.12 seconds = 2 - 3 small
squares

28. INTERVALS
PR Interval
 .12 to .2 sec
QRS Complex
 < .12 sec
R - R Interval
 Distance between
each QRS Complex
Horizontal Axis
 Small box .04 sec
 Large box .2 sec
 5 Large boxes 1
second
Vertical Axis
 Small box .1 mV

29. NORMAL SINUS RHYTHM
Main pacemaker
SA Node

30. Electrical system of the Heart
Normal Sinus Rhythm
A non shockable rhythm

31. Normal Sinus Rhythm

32. Sinus Bradycardia

33. Sinus Tachycardia

34. Premature Ventricular
Contractions
 Premature ventricular contraction (PVC), is a
form of irregular heartbeat in which the
ventricle contracts prematurely.

35. Asystole
There is no electrical activity
A non shockable rhythm

36. Asystole

37. Pulseless Electrical Activity?
Electrical activity with no pulse
A non shockable rhythm

38.  Hydrogen ions (Acidosis)
 Hypokalemia
 Hyperkalemia
 Hypothermia
 Hypovolemia
 Hypoxia
 Tension pneumothorax
 Tamponade- Cardiac
 Trauma
 Thrombosis - Pulmonary
 Thrombosis - coronary
 Toxins
Causes of PEA

39. Lethal Cardiac
Dysrhythmias
 There are two lethal heart rhythms that may be
corrected by early defibrillation:
Ventricular Fibrillation (VF)
Pulseless Ventricular Tachycardia
(VT)

40. HSE NAS Paramedic 3rd Ed. Upskilling
Programme
Irish Ambulance Training
Institute
Ventricular Fibrillation

41. Electrical system of the Heart
Ventricular Fibrillation
A shockable Rhythm

42. HSE NAS Paramedic 3rd Ed. Upskilling
Programme
Irish Ambulance Training
Institute
Ventricular Tachycardia

43. Ventricular Tachycardia

44. REMEMBER !!!
NEVER Forget the Patient!!!
ALWAYS Maintain their dignity at all times with
effective blanketing. ALWAYS Monitor the patient`s
vital signs, NOT JUST The ECG Monitor!

45. PCI Centres
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