Electrocardiogram

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ECG IN 100 STEPS

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WHAT IS ECG ? 1. ECG - Electro-cardio- gram 2. ECG - Graphical recording of electrical activity of human heart 3. ECG - Does not always have a direct correlation with mechanical activity of heart

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ECG READING 4. ECG reading - not a Bali-kera-mala 5. ECG reading - simple arithmetic 6. ECG reading - requires logical sequence + x . . 1 2 3 4

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ECG MACHINE 7. ECG Machine - Modified Galvanometer 8. Recording : produced by vertical movt. of heated Stylus across paper moving horizontally 9. The principle : + Current Electrode +ve Deflection Electrode Current - ve Deflection +

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ECG PAPER 10. ECG paper - Black Background - Heat sensitive - Grey substance coated - Erased by heated stylus 11. ECG paper - moves at a constant speed - 25 mm per second - can be increased to - 50 mm per second 12. ECG paper - has horizontal and vertical lines - I mm apart - just as in a graph paper

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THICKNESS OF LINES 13. Every 5th Horizontal line - Thicker 14. Every 5th Vertical line - Thicker 15. Every 25th Vertical line - Extended up

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DURATION 16. Measured in horizontal direction 1 small division (S.D.) = 1mm = 0.04 sec 17. 1 Big division (B.D.) = 5mm = 0.20 sec 18. 1 Extended division (E.D.) = 25 mm = 1 sec - 2 SD = 0.08 sec - 2 BD = 0.40 sec - 2 ED = 2.00 sec

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AMPLITUDE 19. Measured in vertical direction Principle : 1 mv of current produces a deflection of 10 sd 20. 1 small division (s.d) of height of wave is = 0.1 millivolt. (ie, isd = 0.1 mv) 21. However the amplitude or voltage of defections is expressed in mm of height or depth of waves r s r = 6mm s = 12mm

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CONVENTIONAL 12 LEAD ECG has three types of leads : 22. Standard Limb Leads I II III 23. Augmented Unipolar Limb Leads aVR aVL aVF 24. Unipolar chest leads V1 V2 V3 V4 V5 V6

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II III + + RL Earth LL 27. Positive electrodes placed in LA and LL why ? Because current moving towards a + electrodes produces a + deflection. And that is what we want. aVR aVL + - - - STANDARD LIMB LEADS 25. Recorded by placing (+) electrodes in Right Arm (RA), Left Arm (LA), Left Leg (LL) 26. Recording ECG with RA - + LA + I 1200 III I 0o aVF 900 II 600 -300

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AUGMENTED UNIPOLAR LIMB LEADS 28. Electrode made by connecting RA, LA&LL through 5000 Ohm resistance RA LA CTW LL Neutral Electrode named Central Terminal of Wilson 29. Another electrode placed on RA, LA & LL (Named Exploring Electrode) I + VL II III + VF VR. VL. VF 50 % 30. Disconnecting corresponding leads from CTW Augments current by 50 % aVR aVL aVF VR

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32. Similar exploring electrode placed over the chest at 4 Rt IC space near RSB - V1 4 Lt IC space near LSB - V2 Between V2 and V4 - V3 5 Lt IC space in MCL - V4 Same plane as V4 in AAL - V5 Same plane as V5 in MAL - V6 V1 V2 V3 V4 V5 V6 V3R V4R 33. Rt sided chest leads obtained in place of V3 & V4 on Rt - V3R V4 R UNIPOLAR CHEST LEADS 31. Similar nutral electrode CTW Apex AAL MAL RA LA CTW LL

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NORMAL WAVE PATTERN 34. Each heart beat represented by a regular sequence of wave patterns 35. These waves were named by Einthoven as P.Q.R.S.T and U waves. 36. For convenience these waves can be regrouped as P wave QRS complex, T wave and u wave P Q R S T U P QRS T U

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ELECTRICAL CORRELATION 37. P wave - Atrial depolarisation 38. QRS complex - Ventricular depolarisation 39. T wave - Ventricular repolarisation Atrial repolarisation : some where within - PR- QRS Too small to be seen. T QRS P

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ABOUT EACH WAVE (Definition) 40. P wave - initial wave of heart beat complex - upward and convex 41. Q wave - initial negative deflection following a P wave 42. R wave - initial positive deflection following a Q wave or the - first positive deflection of QRS complex P Q P R P Q R P

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ABOUT EACH WAVE (Definition) (Contd.) 43. S wave - negative deflection following R wave OR - second negative deflection 44. T wave - upward convex wave following QRS 45. U wave - Small upward convex wave following T wave Not always seen. R QRS OR QS R T U T S

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INTERVALS (Definition) 46. PR interval measured from beginning of P to beginning of initial wave of QRS complex Q,R or QS. 47. QRS duration measured from beginning of initial wave of QRS complex to the end of last wave of QRS complex 48. RR interval from tallest point of R to tallest point of next R R P R Q P P QS Q S P RR PP SS Q S

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LEAD SELECTION 49. All leads need through scrutiny before final interpretation 50. For rhythm assessment - lead II and V1 ( P waves best seen) 51. For Axis assessment I II III a VR aVL aVF aVR aVL 1200 III I 0o aVF 900 II 600 -300 -1500

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NOW START READING ECG IN 12 MAJOR STEPS I. STANDARDISATION 52. Standardisation : standard against standard lead - which other leads are read 53. Normal Standardisation 1mv current - produces deflection of 10 sd. . . . Std: 1 mv = 10 sd. 54. Half standard ECG Reduce deflections to 1/2 . . . Std: 1 mv = 5 sd. . . . To calculate voltage X2 Always look for the label 1/2 V1 1/2 V2 etc. }

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II RATE ( Heart Rate) 55. Calculate the rate : 300/ No BD in RR ; III ly 2 BD - 150 Simple method 3 BD - 100 Look for R falling on Bid Divisions 4 BD - 75 If RR = 1 BD, HR = 300/mt. 5 BD - 60 6 BD - 50 56. For more accurate value 1500/ No of Small divisions between adjacent RR 57. If rhythm is irregular Count QRS within 6 sec of ECG paper Multiply by 10 to get HR in 60 sec.

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III RHYTHM 58. Rhythm - is said to be Normal Sinus Rhythm (NSR) if - HR 60-100/mt. - Each P - QRS - T. - PR interval -Normal - QRS duration - Normal 59. Normally slight variation during respiration HR with inspiration with expiration Sinus Arrhythmia Exp Insp Exp 60. Abnormal Rhythm - Arrhythmia - Study lead II & V1 - (Rhythm Strip) - P waves best seen in II & V1 Criteria - Difference between shortest & widest RR should be > 0.12 sec.

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IV AXIS: 61. Axis - means electrical axis of heart Normal Rt axis deviation Lt axis deviation Rt 62. Determination of axis - Crude but simple method study lead I and III alone 63. I III (N) Converge Diverge (LAD) (RAD) Lt Net -ve

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V P WAVE 64. P Wave - normally upward convex - normally inverted in aVR may be in V1 - abnormally inverted in Junctional Rhythm - replaced by fibrillary waves in AF. 65. P wave - normally not > 2.5 mm in width - if 3 mm or more in width & notched - called P mitrale - Left Atrial Enlargement - Mitral Stenosis 66. P wave - normally not > 2.5 mm in height - if 3 mm or more in height and peaked - called P. pulmonale - Right Atrial Enlargement - Cor pulmonale

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VI PR INTERVAL (PQ) 67. PR Interval - Measure from Beginning of P wave to Beginning of QRS complex Normal Range 0.12 - 0.20 sec ie 3-5 sd. 68. PR Interval - Prolonged - More than 0.20 sec. - I0 Heart Block as in - Rheumatic Carditis. 69. PR Interval - Shorter - less than 0.12 seconds - Wolff Parkinson White Syndrome - Junctional Rhythm P Q P Q P Q

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VII Q WAVE 70. Normally. No significant Q in any lead. may be Small q in III, II, V5 V6 71. Q present & more than .04 sec ie, 1 sd. in width It is is significant or pathological It indicates an Electrical Window in myocardium due to Myocardial Infarction ( AMI). 72. Before saying a Q as pathological make doubly sure Because you are diagnosing Transmural Myocardial Infarction In that case Q will be present in more than one lead representing the particular wall of heart. Q .04 sec.

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VIII QRS DURATION 73. QRS Duration - measured from - initial wave of QRS - to the last wave of QRS - Normal < 2 sd. 0.08 sec. 74. QRS Duration - Prolonged - > 2 sd - ventricular Conduction Defect: - RBBB or LBBB or VCD 75. QRS Patterns - Numerous - Vary from lead to lead - Person to person r R

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IX ST SEGMENT 76. ST Segment - From End of S wave ( J point) - To beginning of T. wave Normally - ST same plane as baseline or Isoelectric line 77. ST Segment Elevation in comparison to Isoelectric line 78. ST Segment Depression J IEL Pericarditis (Concave) myocardial injury in AMI (Convex) (Square wave) (Slanting) Q S Angina Pectoris Ventricular Strain pattern in LVH or RVH ( J point elevation of 1mm or more from baseline ) Coving ST

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X . T WAVE 79. T wave normally upright in all leads except in AVR and some times in V1 80. T wave tall and peaked Hyperacute phase of Infarction, Hyperkalemia 81. T wave Symmetrically inverted in Ischaemia of Myocardium T wave Asymmetrically inverted In strain pattern of LVH ( V5 V6) & RVH ( V1) T Symmetrically Assymetrically N Peaked Flat Inverted Inverted Biphasic R T R R T R

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XI R/S IN V1 82. Amplitude of R in V1 ie R/S ratio in V1 Amplitude of S in V1 Normally R in V1 is smaller than S in V1 Therefore R/s Ratio in V1 is <1 83. If R/S ratio in V1 is > 1 ie R is > S in V1 Voltage Criteria for Right ventricular Hypertrophy ( RVH) Other Criteria for RVH: QR pattern in V1,ST dep. & T inv in V1, Persistent Deep S in V5 or V6 84. Other conditions where R> S in V1 True Posterior Wall Infarction Right Bundle Branch Block. r 6 s 13 r R’ s

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XII SV1 + RV6 85. Add Amplitude of S wave in V1 + R wave in V6 or V5 whichever is taller Normal < 35mm 86. If SV1 + RV6 is > 35 mm in a person above 35 yrs It forms the voltage criteria for Left Vetricular Hypertrophy (LVH) 87. Other criteria for LVH are : RV5 or RV6 > 26 mm R1 + SIII > 26mm ST depression T inversion V5 V6 + 15 V6 V1 10 + 25 V6 V1 20 R

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STAGE OF EVOLUTION OF IHD 88. S T ST depression Disappears during chest pain after chest pain 89. Ventricluar ST Tall peaked Activation time Elevation T wave 90. Path Q ST Elevation T Inversion T Angina Pectoris Hyper Acute Phase of Infarction Acute myocardial Infarction ST Q T

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WALL OF INFARCTION 91. Inferior Wall Infarction 92. Anterior Wall Infarction 93. Lateral Wall Infarction

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AGE OF INTERACT 94. If all changes of Acute MI ( ST , T , path Q) are present simultaneously: Recent Infarction 95. If ST becomes Isoelectric but T and Q changes persist: Healing Infarct. 96. If only Q or QS persist long after chest pain : Old Infarct . Q T ST Q T Q QS

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MISCELLANEOUS CONDITIONS 97. Acute Pericarditis : ST elevation in all leads Concordant ST elevation 98. Hyperkalemia : Tall peaked T Prolonged PR Flat P Wide QRS Conduction abnormalities 99. Hypokalemia : Flat or inverted T, Depressed ST Pathological u wave

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100. FINAL IMPRESSION - Eg: NORMAL ECG I. Standardisation 1 mv = 10 sd II. Heart Rate : 75/mt III. Rhythm : NSR IV. Axis : Normal ECG dt 1-11-99 V. P : Normal Normal Sinus Rhythm VI. PR : 0.16 sec No evidence of IHDVII. Q wave : Nil pathological No evidence of chamber VIII. QRS duration : 0. 06 sec enlargement. IX. ST segment : Isoelectric Imp: Normal ECG X. T wave : in all leads XI. R/S V1 : 3 / 6 mm XII. SV1 + RV6 : 30 mm

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100. FINAL IMPRESSION - Eg : ABNORMAL ECG I. Standardisation : 1 mv = 10 sd II. Heart Rate : 54/mt III. Rhythm : Sinus Bradycardia ECG dt 2-1-99 IV. Axis : Left Axis Deviation Sinus Bradycardia I0 Heart Block V. P : Wide and notched Acute Inferior Wall Myocardial Infarction VI. PR : 0.28 sec VII. Q wave : path Q in II III aVF Lt Atrial Enlargement VIII. QRS duration : 0.06 in V1 Lt Ventricular Hypertrophy IX. ST segment : Elevation II III aVF with strain Slanting ST in V5 V6 X. T wave : Inverted II III aVF V5 V6 XI. R/S V1 : 3/20 MM XII. SV1 + RV6 : 20+26 = 46 mm

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