This presentation is very useful for undergraduate medical students, premedical students to know about the basics of ECG in a very less time.This presentation teaches us how to proceed systematically to interprate an electrocardiographic tracing.

1. Dr Awadhesh Kr Sharma, MBBS,MD,DM,FACC,FSCAI
Assistant Professor
LPS Institute of Cardiology, Kanpur, UP

2.  Dr. Awadhesh Kumar Sharma is a young, diligent and dynamic interventional cardiologist. He did his graduation from GSVM Medical
College Kanpur and MD in Internal Medicine from MLB Medical College Jhansi. Then he did his super specilization(Doctoral) degree
DM in Cardiology from Atal Bihari Vajpai institute of medical sciences & DR Ram Manohar Lohia Hospital New Delhi. He had excellent
academic record with Gold medal in MD . He was also awarded chief minister’s medal in 2009 for his academic excellence by former
chief minister of UP Hon. Km Mayawati in 2009.He is also receiver of GEMS international award. He had many national &
international publications. He had special interest in both invasive & non invasive cardiology. He had performed more than 10000
invasive cardiac intervention procedures successfully till date including coronary angiography, simple & complex angioplasty,
peripheral vessels angiography & angioplasty, carotid angiography & angioplasty, ASD ,PDA device closures, Mitral & pulmonary
valvotomy. He is also in editorial board of many national & international journal- Journal of clinical medicine &
research(JCMR),Clinical cardiology update, United Journal of Cardiology and Cardiovascular Medicine ,EC Pulmonology and
Respiratory Medicine,EC Cardiology. He is also active member of reviewer board of many journals. He is also trainee fellow of
American college of cardiology. He is active member of many professional bodies including Indian Medical Association, Cardiological
Society of India, APVIC, ICC,API. He had worked in NABH Approved the Gracian Superspeciality Hospital Mohali as Consultant
Cardiologist since 2014-2016. Currently he is working as Assistant Professor of cardiology at LPS Institute of Cardiology, GSVM
Medical college, Kanpur(UP)under Govt of UP. He was awarded with prestigious fellowships of American college of cardiology(FACC)
and FSCAI. He is actively involved in creating public awareness on different health issues pertaining to heart via his You tube channel-
Happy & Healthy Heart.

3.  To have basic understanding of ECG waves & intervals.
 Interpretation of ECG
 Outline the criteria for the most common electrocardiographic diagnoses in adults.
 Describe critical aspects of the clinical application of the ECG

4. Still had same clinical value.
Einthoven with his string
galvanometer
 Invented by Einthoven in 1901.(string galvanometer).
 In 1910 –emerged to clinical setting as fundamental
diagnostic test to assess heart electrical activity.
 1924 - The noble prize for physiology or medicine is
given to William Einthoven for his work on ECG

5. Conduction system
SA node-AV node-LBB & RBB-
His-purkinje system
 SA node
 AV node
 Bundle branch-Right bundle(RBB) & Left
bundle-LBB(Left anterior fascicle-LAF and left
posterior fascicle-LPF)
 His Purkinje system

6.  Depolarization( systole, contraction)-Atrial &
ventricular
 Repolarization(diastole, relaxation )- Atrial &
ventricular

7. Single channel ECG machine trace
ECG trace from 3
channel machine
 Single channel ECG-one lead trace at a time.
 Three channel- four leads at a time
 12 channel- 12 leads simultaneously

8.  Augmented limb leads (increase voltage or amplitude
by 50%)
aVR (right arm), aVL (left arm), aVF (left foot)
Color coding of limb electrode
RA-Red, LA-yellow, LL-green, RL-black
Standard bipolar limb leads
I(LA &RA), II(LL & RA), III(LL & LA)

9. Precordial leads
 Precordial leads
 V1-V6
 Views heart from horizontal plane

10. Standard Chest Lead Electrode Placement

12. 14 points to be remembered
1. Standardization
2. Rate
3. Rhythm
4. Axis
ECG Waves
1. P wave
2. Q wave
3. QRS
wave/voltage
4. T wave
5. U wave
Intervals/segments
1. PR interval
2. QRS
interval/duration
3. ST segment
4. QT interval
Precordial R wave
progression

13.  The first step while reading ECG is to look for
wheather standardization is properly done.
 Look for the vertical mark and see that the mark
exactly covers two big squares(10 mm or 1mV) on the
graph.
 Standard calibration
 25 mm/s
 0.1 mV/mm

14. ECG Paper ECG Paper
 Horizontal(x axis)-Speed 25 mm/sec
 1 large square(5mm)= 0.2 sec
 1 small square(1mm)=0.04 sec

15. Vertical(y axis)-amplitude
10 mm=1mV Caliberation

16. HR=300/No of large square
 For regular rhythm
 Rate=300/number of large square between two RR
interval
=1500/number of small square(more accurate)
Rate-
Normal- 60-100 beats/minute
>100beats/minute- tachycardia
<60 beats/minute- bradycardia

17. HR=8X10=80/minute
 For irregular rhythm
 6 seconds rule
 Count number of QRS complex during 6
seconds i.e. 30 large squares and multiply it
by 10.
 1 large square=0.2 second
 30 large square=30x0.2=6 seconds

18. Regular rhythm
Ventricular Premature
Complexes
 Regular-RR interval regular and fixed
 Regularly irregular-VPCs
 Irregularly irregular-AF
Atrial fibrillation

19. Hexaxial system
 Vertical orientation or alignment of the heart
in the thoracic cavity
 Normal axis(-30 to +90 degree)
 Left axis(-30 to -90 degree)
 Right axis(+90 to +180 degree)
 Indeterminate/north west axis(-90 to -180degree)

21. Negative in I-RAD
Positive in I, negative in III-
LEFT AXIS

22. P wave genesis P wave
 Due to atrial depolarization(contraction)
 No apparent wave because of atrial
repolarization since it is of small amplitude
and got hidden.
 Initial part is due to right atrial depolarization
and later part is due to left atrial
depolarization.
 Inter atrial conduction occurs through
Bachmann bundle.

23. P wave abnormalities
 Left atrial abnormality
 Prolonged P wave duration that >120msec(3 small
square)
 Notched P wave i.e. P mitrale
 Right atrial abnormality
 Peaked P wave with amplitude more than 0.25
mV(2.5mm) in lead II-P pulmonale
 Prominent initial positivity in V1 >1.5mm.
LAA
RAA

24. Prolonged PR interval
 Prolonged PR interval i.e. >200
milliseconds suggestive of first
degree AV block.
 Can be due to drug effect like beta
blockers.

25. QRS Complexes
 First negative wave-q(first initial negative
wave) or Q wave(first initial only negative
deflection).
 First positive deflection-r or R wave
 Second negative deflection-s or S wave
 Second positive deflection- r’ or R’ wave

26.  Suggestive of old infarction or non viable
myocardium

27.  LVH
1. SV1+RV5>35mm(3.5mV)
2. R aVL >11mm(1.1mV)
 RVH
1. Tall R in V1>6mm(0.6mV)
2. Increased R/S in V1>1

28.  Normal duration <120 m sec
 If QRS>120msec-intraventricular conduction
defect
 LBBB
1. QRS>120msec
2. Deep S wave in V1 and V2
3. W pattern in V1
 RBBB
1. QRS>120msec
2. Rsr’,rsR’ or Rsr’ pattern(M pattern) in leads
V1 and V2

29. RBBB LBBB

30.  From r in V1 to R in V6
 Transition zone V3,V4
 Slow progression of R wave- COPD,AWMI

31.  Due to ventricular repolarization.
 ST segment depression-myocardial ischemia
 ST segment elevation-myocardial infarction

32.  Tall T wave-hyper acute injury
 Tall, tented T wave-
hyperkalemia
T wave inversion-
myocardial ischemia

33.  Duration of ventricular depolarization &
repolarization
 QTc=QT/ (RR)½
 QTc=QT+1.75(HR-60)
 Upper limit for QTc is 460 msec for women
and 450msec for men.

34.  Low amplitude wave
 Seen in lead V2,V3 at slower heart
rates

35. ECG
Acute
coronary
syndrome

37.  J point – where the QRS complex and ST segment meet
 ST segment elevation - evaluated 0.04 seconds (one small box) after J point
The J Point

38.  Coved shape usually indicates
acute injury.
 Concave shape is usually benign
especially if patient is
asymptomatic.

39. Anatomic Groups

40. Anatomic Groups

41. Anatomic Groups

42. Anatomic Groups

43. Anatomic Groups