The document provides information on the history and development of the electrocardiogram (ECG). It discusses key individuals who contributed to advancements in ECG technology and interpretation. The summary also outlines the main components of an ECG reading including waveforms, intervals, leads, and how to interpret cardiac electrical activity and identify abnormalities.

1. ECG

2. HISTORY
 1842- Carlo Matteucci -electricity is a/w heart beat
 1876- Marey - electric pattern of frog’s heart
 1895 - William Einthoven - invention of EKG
 1924 - Noble prize - Einthoven for EKG

3.  1938 -AHA & Cardiac society of great Britain
defined position of chest leads
 1942 -Goldberger increased Wilson’s Unipolar lead
voltage by 50% & made Augmented leads

6. ELECTROCARDIOGRAM
 Is a recording of electrical activity of heart
conducted thru ions in body to surface

7. ECG INTERPRITATION STEPS
 Rate
 Rhythm
 Cardiac Axis
 P – wave
 PR - interval
 QRS Complex
 ST Segment
 QT interval (T & U wave)
 Other ECG signs

8. CARDIAC
ELECTROPHYSIOLOGY
 Electrical activity is governed by multiple trans
membrane ion conductance changes
 3 types of cardiac cells
1. Pacemaker cells - SA node, AV node
2. Specialized conducting tissue - Purkinje
fibres
3. Cardiac myocytes

10. WAVEFORMS AND
INTERVALS

11. ECG GRAPH PAPER
 Runs at a paper speed of 25 mm/sec
 Each small block of ECG paper is 1 mm2
 At speed of 25 mm/s, 1 small block = 0.04 s
 Voltage: 1 mm = 0.1 mV between each individual
block vertically

12. 5 mm
1 mm
0.1 mV
0.04 sec
0.2 sec
Speed = rate
Voltage
~Mass
ECG GRAPH PAPER

13. ECG LEADS
Leads are electrodes which measure the difference
in electrical potential between either:
1. Two different points on the body (bipolar leads)
2. One point on the body and a virtual reference
point with zero electrical potential, located in the
center of the heart (unipolar leads)

14. The Concept of a “Lead”
RA
- +
RA
LL
+
+
- -
LA
LL
LA
LEAD II
LEAD I
LEAD III
Leads I, II, and III
• By changing the
arrangement of which
arms or legs are
positive or negative,
three unipolar leads
(I, II & III ) can be
derived giving three
"pictures" of the
heart's electrical
activity from 3 angles.
Remember, the RL
is always the ground
I
II III

15. ECG LEADS
 The standard ECG has 12 leads:
3 Standard Limb Leads
3 Augmented Limb Leads
6 Precordial Leads
 The axis of a particular lead represents the
viewpoint from which it looks at the heart.

16. ECG LEADS
 Gold Berger :aV frontal leads
 Wilson & co-workwers :chest leads

17. STANDARD LIMB LEADS

18. PRECORDIAL LEADS

19. PRECORDIAL LEADS

21. STANDARDIZATION

22. 300
number of BIG SQUARE b/w R-R
RATE
Rate =
OR
1500
number of SMALL SQUARE b/w R-R
Rate =

23. RATE

24. RHYTHM
 P -QRS relationships- Lead II is commonly used
Regular or irregular?
 Ventricular rhythm – measured by R-R interval
 Atrial rhythm - measured P-P interval.

25. Normal Sinus Rhythm
ECG rhythm -usual rate as per age of child, every P
wave must be followed by a QRS & every QRS is
preceded by P wave.
P wave is upright in leads I and II

26. NORMAL SINUS RYTHM
 Originates in the sinus node
 Rate between 60 and 100 beats per min
 P wave axis of +45 to +65 degrees (Tallest p
waves in Lead II)
 Monomorphic P waves
 Normal PR interval of 120 to 200 msec
 Normal relationship between P and QRS
 Some sinus arrhythmia is normal

27. AXIS
 Axis refers to general direction of heart's
depolarization wave front (or mean electrical
vector) in the frontal plane.
 In healthy conducting system - axis is related to
where the major muscle bulk of heart lies.

28.  William Einthoven developed a system capable of
recording small signals & recorded 1st ECG.
 Leads were based on Einthoven triangle a/w limb
leads.
 Leads put heart in middle of a triangle

29. EINTHOVEN TRIANGLE

32. AXIS
1. Lead I & aVF divide
thorax into quadrants,
(Lt, N , Rt, No Man's)
2. If Lead I & aVF are both
upright- Axis is normal.
3. If lead I is upright & lead
aVF is downward - Axis
is Left.

33. AXIS
4. If lead aVF is upright
& lead I is downward -
Axis is Rt
5. If both leads are
downward - Axis is
extreme Right
Shoulder & most often
is Vent. Tachy

37. Cardiac Axis Causes
LAD Pregnancy, obesity; Ascites ,
abdominal distention, tumour ; LAH,
LVH
RAD N finding in children & tall thin adults,
COPD, RVH, Anterolateral MI.
North West Emphysema, Hyperkalaemia , Lead
transposition, Artificial cardiac pacing,
VT

38. P WAVE
 Depolarization of both atria
 Relationship b/w P & QRS - distinguish various
arrhythmias
 Shape & duration of P - indicate atrial
enlargement

43. P WAVE
 Always +ve in lead I & II
 Always -ve in lead aVR
 <2 small sqs - duration
 <2 small sqs - amplitude
 Biphasic in lead V1
 Best seen in lead II

44. P-PULMONALE P-MITRALE

45. PR INTERVAL
 Onset of P wave to onset of QRS
• Normal = 0.12 - 2.0 sec
• Represents A to V conduction time (via His
bundle)
 Prolonged PR interval indicate AV block

46. PR INTERVAL
 Onset of P wave to onset of QRS
• Normal = 0.12 - 2.0 sec
• Represents A to V conduction time (via His
bundle)
 Prolonged PR interval indicate AV block

47. VENTRICULAR
DEPOLARIZATION
Includes
 Bundle of His
 Bundle Branches
Right
Left
Septal
Anterior
Posterior
 Terminal Purkinjie fibers

48.  Ventricular Waves
Q wave – 1st downward deflection after P wave
Rwave – 1st upward deflection after Q wave
S wave – 1st downward deflection after R wave

49. QRS COMPLEX
 Ventricular depolarization
• Is > P wave d/t > Ventricular mass
• Normal duration = 0.08 - 0.12 secs

51. ST SAGMENT
Connects QRS complex & T wave
 Duration = 0.08 - 0.12 sec

53. T WAVE
 “small to moderate” size +ve deflection wave
after QRS complex,
Ht is 1/3rd - 2/3rd that of corresponding R
wave

55. U WAVE
 Septal repolarization (not always seen on ECG)

56. QT INTERVAL
Beginning of QRS to end of T wave
 Normal QT is usually about 0.40 sec
 QT varies based on HR- faster HR ,shorter QT
 Bazett’s formula: QTC = QT / √ RR
 Fredericia’s formula: QTC = QT / RR 1/3
 Framingham formula: QTC = QT + 0.154 (1 – RR)
 Hodges formula: QTC = QT + 1.75 (HR– 60)

57. PROLONGED QT INTERVAL
 CAD
 Cardiomyopathy
 Severe Bradycardia, High-Grade AV Block
 Anti-Arrhythmics
 Psychotropic Drugs
 Hypocalcemia
 Autonomic dysfunction
 Hypothyroid
 Hypothermia
 Congenital Long QT Syndrome

58. SHORT QT INTERVAL
 Digitalis effect
 Hypercalcemia
 Hyperthermia
 Vagal stimulation

59. VENTRICULAR
HYPERTROPHY
 RVH = R in V1 + S in V6
 LVH = S in VI + R in V6

60. THANK YOU