ECG or electrocardiography is the graphical representation of electrical impulses produced by the heart. The electrical impulses form due to movement of ions in the myocardial cells representing depolarization and repolarization, denotes the conduction pathway of heart, which coincides with cardiac cycle. Apart from normal electrocardiography common arrhythmias are also discussed during this session.

1. TUTORS
SCHOOL OF NURSING
ASIA HEART FOUNDATION
ELECTROCARDIOGRAPHY

2. ECG is a graphical representation of the
electrical impulses produced in the heart.
The waveform of ECG represent electrical
activity produced by the movement of ions
across the membrane of myocardial cells,
representing depolarisation and
repolarisation.

3.  Automaticity-ability to generate an electrical
impulse spontaneously & repetitively
 Excitability-ability to be electrically stimulated
or respond to an electrical stimulus
 Conductivity-ability to receive an electrical
stimulus and transmit to other cardiac cells
 Contractility-ability to response mechanically to
an impulse

5.  3 major cations
 K-performs a major function in cardiac
depolarization and repolarization
 Sodium plays a vital part in myocardial
depolarization
 Calcium is important in myocardial depolarization
and contraction.
 Magnesium-acts as transporter for Na & K across
cellular membranes. Also plays an important
function in muscular contraction

6.  Resting cardiac cells (Polarization) –inside the
cell is negatively charged. K is greater in the
cell; Na greater outside the cell (positively
charged)-Resting membrane potential
 Depolarization (action Potential)-sodium-
potassium exchanged pump resulting in positive
polarity inside the cell membrane. Myocardial
contraction occurs.
 Repolarization-recovery or resting phase;
positive charges are again on the outside and
negative charges in the inside

8. ECG Graph Paper
• Runs at a paper speed of 25 mm/sec
• Each small block of ECG paper is 1 mm2
• At a paper speed of 25 mm/s, one small block
equals 0.04 s
• Five small blocks make up 1 large block which
translates into 0.20 s (200 msec)
• Hence, there are 5 large blocks per second
• Voltage: 1 mm = 0.1 mV between each
individual block vertically

9. Limb leads
 Bipolar leads-measures activity between
2 points (I, II, III)
 Unipolar leads-positive electrodes only-
aVR, aVL, aVF
Chest leads-6 precordial leads

10. • Limb leads are I, II, II.
• Each of the leads are bipolar; i.e., it
requires two sensors on the skin to make a
lead.
• If one connects a line between two
sensors, one has a vector.
• There will be a positive end at one
electrode and negative at the other.
• The positioning for leads I, II, and III were
first given by Einthoven. Form the basis of
Einthoven’s triangle.

11.  Bipolar leads record voltage between electrodes
placed on wrists & legs (right leg is ground)
 Lead I records between right arm & left arm
 Lead II: right arm & left leg
 Lead III: left arm & left leg

16.  P wave caused by atrial depolarization
 Duration – 0.06-0.12 (1-3 small box)

17. •Q wave greater than 1/3
the height of the R wave,
greater than 0.04 sec are
abnormal and may
represent MI

18.  QRS complex caused by ventricular
depolarization
 duration -0.12-0.20 (3-5 small box)

19.  T wave results from ventricular
repolarization
 Duration-0.16sec (4 small box)

20. • . PR interval: from onset of P wave to
onset of QRS
• Normal duration = 0.12-0.2sec
(120-200 ms) (3-5 horizontal boxes)
• Represents atria to ventricular
conduction time (through His
bundle)
• Prolonged PR interval may indicate
a 1st degree heart block

21.  ST segment:
• Connects the QRS complex and T wave
• Duration of 0.08-0.12 sec (2-3 small
box)
 QT Interval
• Measured from beginning of QRS to the
end of the T wave
• Normal QT is usually about 0.40 sec(10
small box)
• QT interval varies based on heart rate

22.  Rate - 60 -100 b/min
 Rhythm- regular
 P wave- normal
 PR interval- normal
 QRS complex- normal

23.  heart rate= 1500
small box in RR interval
 heart rate= 300
large box in RR interval
 6 second method = no. of QRS complexes
in a 6 sec strip x 10 (30 largeboxes in 6 sec
strip)

25. Calculate the heart rate

26. Bradycardia

27.  Rate - <60 b/min
 Rhythm- regular
 P wave- normal
 PR interval- normal
 QRS complex- normal

28. Adverse effects:
Dizziness, weakness,
syncope, diaphoresis,
pallor, hypotension

29.  P wave- followed by QRS complex
 PR interval-prolonged (>0.20Sec)
Length of prolonged PR interval constant
KEY TO REMEMBER- wife is waiting at home ,
husband comes home late every night , but he
always comes home and it’s the same time every
night

30.  Progressing lengthening of PR interval untill a
QRS complex is dropped
 PP interval is constant
 QRS complex is narrow
KEY TO REMEMBER- wife is waiting at home ,
husband comes home later and later every night
, untill one night he does not come home at all

31. If drug toxicity is the cause,
withhold drug
Artificial pacemaker may be
used as an electrical back up
If rate related sympoms apear,
rate can be accerated by
administering Atropine
cautiously

32.  PR interval is constant
 PP interval regular
 RR interval irregular as of the intermittent and sudden
appearance of drop beat. P waves comes on time but no
QRS complex follows
 QRS complex is wider
KEY TO REMEMBER- wife is waiting at home ,
sometime husband comes home sometime he
does not. When he comes home it always same
time.

33. If drug toxicity is the
cause, withhold drug
TPI or PPI

34.  RR interval is constant
 PP interval usually constant
 atrial rate is usually faster than ventricular rate
 No relation between P wave and QRS complex
KEY TO REMEMBER- wife is no longer is waiting at
home , she and her husband now both separate
schedule, no relationship. Each spouse has a
regular individual schedule

35. If drug toxicity is the
cause, withhold drug
TPI or PPI

37.  Rate –60-100b /min
 Rhythm- irregular
 P wave- abnormal shape
 PR interval- normal
 QRS complex- normal (usually)

38. Treatment-
 Lifestyle modification
 Drugs like quinidine,
procainamide.

40.  Rate – 101-200 b/min
 Rhythm- regular
 P wave- normal
 PR interval- normal
 QRS complex- normal

41. Adverse effects
Angina, dizziness,
hypotension, increased
in cardiac workload

42.  Rate -150-220 b/min
 Rhythm-regular
 P wave-abnormal,may be hidden in the
preceeding T wave
 PR interval-normal or shortened
 QRS complex- normal (usually)
 Paroxysmal-starts & ends abruptly

43.  Rate and rhythm- atrial -200-350 b/min
and regular
ventricular- > or < 100 bpm
and regular /irregular
 P wave-saw toothed pattern
 PR interval-not measurable
 QRS complex- normal (usually)

44. Treatment:
digitalis,
cardioversion,
calcium channel blockers,
beta blockes
 Radiofrequency catheter
ablation of reentry pathways

45.  Rate –atrial rate 400-600 bpm
 Rhythm- RR Interval irregular
 P wave-no P wave only fibrillatory wave
 PR interval-not measurable
 QRS complex-narrow complex

46. Treatment-
Digoxin,
Beta – blocker,Calcium channel
blocker
 Antidysrhythmic agent
 Cardioversion if patient is
unstable

47.  Rate -=> 100bpm
Rhythm-regular
PR interval- Not measurable
 QRS complex-wider than
normal

48.  Monomorphic VT
 Polymorphic VT

51.  Rate – not countable
 Rhythm-irregular
 P wave-absent, fibrillatory wave
 PR interval-not measurable
 QRS complex-absent

52.  Rate - zero
 Rhythm- none
 P wave- none
 QRS complex- none

53. Cardiac standstill
Absence of all ventricular
activity-no waveforms
Check on 2 leads-? Very fine Vfib
Clinical death-absence of pulse
and respirations

56. ????
 VENTRICULAR tachyardia
(monomorphic)

57. ????
Sinus tachycardia

58. ????
3 rd degree AV block

59. ????
 VENTRICULAR tachyardia
(polymorphic)

60. ????
2 nd degree AV block (mobitz
type I)