ULF - Electrocardiography For Students -

Electrocardiography – PART 1 : 

Electrocardiography – PART 1 Dr. S. Aswini Kumar. MD Professor of Medicine Medical College Hospital Thiruvananthapuram Kerala, South India draswinikumars@gmail.com 1

Definition: : 

Definition: ECG is the graphical recording of electrical activity of human heart recorded from the body surface 2

Advantages : 

Advantages ECG is immediately available, non-invasive, inexpensive and a highly versatile tool 3

Importance : 

Importance Interpretation of the hearts electrical messages is a valuable and easily attained skill useful in diagnosis and treatment 4

Not a “Bali kera mala” : 

Not a “Bali kera mala” It is easy, provided you learn it systematically, thoroughly and practice it daily 5

Uses of ECG: : 

Uses of ECG: There are several uses of ECG in the general practice and consultant practice Heart Rate Normal / Tachycardia / Bradycardia Arrhythmias Ventricular / Supraventricular Heart Blocks AV Nodal / RBBB / LBBB Electrolyte Imbalance Hypokalemia / Hyperkalemia Carditis Myocarditis / Pericarditis Drug Effect Digoxin / Quinidine / Adriamycin Coronary Circulation Ischemia / Injury / Infarct Electrical Axis Normal / Right axis / Left axis Chamber Enlargement LAE / RAE / LVH / RVH 6

Willem Einthoven : 

Willem Einthoven It was Einthoven who discovered the ECG machine in 1890 and he was awarded Nobel Prize in the year 1924 7

ECG Machine : 

ECG Machine The ancient ECG machine - the patient dipping both hands and the left leg in buckets containing salted solution 8

Modern ECG Machine : 

Modern ECG Machine The present day ECG machines are compact, portable as well as computerized; some with multi channel recordings 9

The Principle : 

The Principle ECG Machine is a modified galvanometer in which the recordings are made by electrodes placed on the body Current moving towards +ve electrode Current moving away from +ve electrode + + Positive deflection Negative deflection 10

ECG Paper : 

ECG Paper The ECG paper is actually a black paper on which a heat sensitive, white or rose substance is coated Black paper Cheap Heat sensitive substance coated No ink 11

The Graphical Recording : 

The Graphical Recording 12

The Duration : 

The Duration The duration is measured in the horizontal direction. One small division = 1mm and eq. to 0.04 seconds 13

Conversion : 

Conversion Then 2 SD = 0.08 sec and 3SD = 0.12 sec , 4SD = 0.16sec, 5SD = 0.20sec, so on and so forth 14

Amplitude : 

Amplitude The calculation is one mille volt of current produces a deflection of 10 small divisions (sd) 15 Lead V6 16mm 6mm

Leads in ECG : 

Leads in ECG The ECG discovered by Einthoven had only one set consisting of three leads I, II & III 16

Standard Limb Leads : 

Standard Limb Leads Standard limb leads I, II and III are obtained using a +ve and -ve electrode placed on the wrists and ankles       I II III 17

Augmented Unipolar Lead aVR : 

Augmented Unipolar Lead aVR A neutral electrode is made by joining 2 limbs and an exploring electrode is placed in the 3rd limb Exploring Electrode Neutral Electrode 18

Chest Leads V1 to V6 : 

Chest Leads V1 to V6 A neutral electrode is made by connecting all 3 limbs and exploring Electrodes are then placed over chest 19

Right Chest Leads : 

Right Chest Leads Right sided leads V3R and V4R are recorded by placing electrodes on the right side of chest 20

Orientation of the leads : 

Orientation of the leads The limb leads are oriented to the frontal plane and the chest leads are oriented to the horrizontal plane 21

The Cardiac Cycle : 

The Cardiac Cycle The P, Q, R, S, T & U waves were named so by Einthoven, together they represent the events of the human cardiac cycle 22 P Q T P R S

The waves and intervals : 

The waves and intervals The waves are regrouped as P wave, QRS complex, ST segment, T wave and U wave and the intervals PR, QRS, QT 23

Electrical Correlation : 

Electrical Correlation P wave represents atrial depolarization, QRS complex - ventricular depolarization, T - ventricular repolarization 24

Now read ECG in 12 steps : 

Now read ECG in 12 steps Normally, one complex with all components p, q, r, s, t and u waves is good enough for interpretation of ECG Long leads Short leads 25

Step 1. Standardization : 

Step 1. Standardization It is the first lead of the electrocardiogram, the standard against which other leads are to be read 26

What is Standardization? : 

What is Standardization? When 1 milli volt of current is given by the machine it produces a square wave deflection of 10 small divisions 1 mV 10 sd 27 1 mV 5 sd

Look for standardization in every ECG : 

Look for standardization in every ECG The first step in reading an ECG is to look for the presence and correctness of the standardization 28

Step 1: Standardization : 

Step 1: Standardization Step 01. Std: 1mv = 10sd 29 There is a standardization lead looking like a rectangle the height was 10mm there were no half standardization leads

Step 2: Calculation of Heart rate : 

Step 2: Calculation of Heart rate If the rhythm is regular, count the number of BDs between two adjacent R waves, then divide 300 with that value 30 If RR = 1 BD, HR will be = 300/min. If RR = 2 BD, HR will be = 150/min. If RR = 3 BD, HR will be = 100/min. If RR = 4 BD, HR will be = 75/min. If RR = 5 BD, HR will be = 60/min. If RR = 6 BD, HR will be = 50/min.

Heart Rate in Irregular Rhythm : 

Heart Rate in Irregular Rhythm Count the number of QRS complexes within 6 seconds of ECG paper, then multiply by 10 to get heart rate in 60 seconds 31

Step 2: The Heart Rate : 

Step 2: The Heart Rate The rhythm is regular Counted the big divisions between two R waves Divided the number 300 with the no of big divisions The vallue is 75/mt Step 02 – Heart Rate : 75/mt 32

Step : Rhythm of the Heart : 

Step : Rhythm of the Heart Rhythm of heart is the regularity or irregularity of the heart action, studied using a long lead II or V1 33

Please search : 

Please search Continued as Electrocardiography – Part 2 Thank You 34