Electrocardiogram

ecg

1. Electrical Activity of the Heart By dr shazia askari

2. ECG(electrocardiograph) ECG is define as ‘’ recording of electrical activity of heart on a graph paper.’’ Or Graphical representation of electrical activity of heart.

3. Electrocardiograph. The machine which is used to record the electrical activity of heart is ELECTROCARDIOGRAPH. a) ECG machine. b) power lab.

4. Electrocardiogram. The graph on which this electrical activity is recorded is called ELECTROCARDIOGRAM.

5. Significance of ECG. ECG gives information about rate and rhythm of the heart. The physical orientation of heart i.e axis. Its a diagnostic tool for various heart conditions like hypertrophies , ischemia, infarction , arrhythmias conduction problems and pace maker activity. ECG does not provide information about mechanical activity.

6. ECG paper. This is long role of paper ,composed of small squares . One square is 1 mm wide and 1 mm high. On ECG paper there are thick lines, between two thick lines there are 5 small squares. The speed of ECG machine is 25 mm per second.

7. ECG paper.

8. ECG Paper. The time internal of each small square can be calculated as 25 small sqrs are equal to 1 second. 1 small sqr is equal to 1/25 second. i.e 0.04 seconds.

9. ECG paper vertically the small square represent the amount of electrical potential. One small sqr represent the potential of 0.1 mv. 10 small squares represent the potential of 1 mv.

10. ECG leads. leads are electrodes which record the electrical potential of heart at different sites. There are 12 ECG leads. a) 3 bipolar limb leads. b) 3 augmented limb leads.(unipolar). c) 6 chest leads. .

11. Bipolar limb leads. Lead 1 = left arm + ve , right arm _ ve Lead 2 = right arm _ ve ,left leg + ve .. Lead 3 = left arm _ ve , left leg + ve .

12. Augmented limb leads. AVR attach to right arm.. AVL attach to left arm. AVF attach to left foot .

13. Einthoven”s triangle Einthoven s triangle is a diagrammatic way of illustrating that the two arms and left leg form the apices of triangle surrounding the heart. It is an equilateral triangle.

14. Einthoven “s rule. Einthovens law states that if the electrical potentials of two leads are known at any instant ,the third can be determine by simply summing the first two.

15. Waveforms in ECG Lecture no 2

16. Always remember. Positive electrode is always a reference electrode. Depolarization wave moves toward the positive electrode gives positive deflection. Depolarization wave move away from positive electrode gives the negative deflection.

17. Wave forms. P wave Atrial depolarization QRS complex Ventricular depolarization T wave Ventricular repolarization

18. Basic terminologies Base line : flat , straight and isoelectric line Wave form :deviation or movement away from base line may be upward or downward Segment : A line between two waves Interval : a wave form plus a segment this shows time duration Complex : combination of several wave form without segment.

19. P wave P Wave shows atrial depolarization.. Its duration is 0.1 sec (2 and half small sqr ) and height is 2.5 mv (2 and half small sqr ). Presence of p waves in ECG strip shows the sinus rhythm.

20. Abnormalities of P wave. P . pulmonale :- This is tall and peaked P wave in lead 1 and lead 2 and 3 in right atrial hypertrophy. (pulmonary hypertension). P. mitrale ;_ It is biphasic or broad P wave seen in left atrial hypertrophy.(mitral stenosis). -. Best seen in lead 2.

21. P wave. Inverted P wave :- may be present in . a) Normally in lead V 1 and V2.. b) In dextro cardia . c) I ncorrectly placed electrodes.

22. QRS complex. QRS complex represent the ventricular depolarization. its normal duration is about 0. 08 seconds.( less than 2 small sqr ) and hight is about 5 to 20 small sqrs . It is a wide complex because it mask the atrial repolarization. Q wave is first wave of this complex but often absent.

23. QRS complex. Q wave present the interventricular septal depolarization. It is first wave in ECG with negative deflection. Q wave greater than 1/3 the height of the R wave, greater than 0.04 sec are abnormal and may represent the old infarction. .

24. Low voltage QRS complex. when the height of R or S wave is not more than 5mm… it is seen in.. Hypothyroidism. Pericardial effusion. Thick chest wall. Problem in ECG machine.

25. High voltage QRS complex. This is present in ventricular hypertrophies. The maximum voltage of QRS complex may be 35 mv(35 small square). V1 and V2 show high voltage QRS complex in right ventricular hypertrophy.( s wave) V5 and V6 show such QRS complex in left ventricular hypertrophy. (r wave)

26. T Wave. it represent the ventricular repolarization. It is repolarizing wave but shows the upward deflection because the part depolarized in the last is first to be repolarized,, that is base of heart depolarized in the last but is first to be repolarized.

27. T wave. T wave should not be more than one third of R wave. T wave inversion represent ischemia of heart. Tall and peaked R wave is present in hyperkalemia. Flattened R waves in pericarditis and myocarditis.

28. PR interval. This is from beginning of P wave to the beginning of Q wave. Its normal duration is from 0.12 to 0.2 sec.. It represent the conduction time of impulse from SA node to the ventricles and AV delay.

29. Prolong PR interval. P rolong PR interval shows delayed conduction from SA to AV node…. In first degree heart , 2 nd degree and complete heart block. Digitalis therapy. Hyperkalemia.

30. First degree heart block. A-V BLOCK, FIRST DEGREE Atrio -ventricular conduction lengthened Interval is about 0.2 to 0.3 sec.                       

31. Second degree heart block. A-V BLOCK, SECOND DEGREE Sudden dropped QRS-complex PR interval is about 0.4 sec.                                                                                                   

32. 3 rd degree heart block

33. 3 rd degree heart block. When there is AV block , atria continue to beat at normal rhythem while new pace maker develops in purkinjie system with a rate of 15 to 50 beats /min. With a sudden block purkinje system cannot take over pace maker activity immediately ,it takes about 16 to 30 sec. during which ventricles fail to contract and person faint. This delayed pickup of heart beat is called stokes A dams syndrome.

34. QT interval Measured from beginning of Q to the end of the T wave . Its duration is about (10 small sqrs ). . it indicates total systolic time of ventricles.

35. RR interval.

36. ST segment. this segment present between S wave and T wave. It represent the plateau phase. its duration is 0.04 sec .

37. J point. The exact point at which all parts of ventricles are depolarized i.e at the just end of QRS comples and just at the begining of ST segment. At the point potential of ECG is zero with no current is flowing through heart.

38. ST segment Elevation . Seen in recent MI and hyperkalemia. Depression. Seen in ischemia, digitalis therapy and hypokalemia.

39. Lecture 3 ECG

40. Electrophysiology If an electrode is placed so that wave of depolarization spreads toward the recording electrode, the ECG records a positive (upward) deflection. If wave of depolarization spreads away from recording electrode, a negative (downward) deflection

41. Waves in limb leads.

42. Waves in augmented limb leads

43. ECG recording of electrical activity not the mechanical function ECG is not a direct depiction of abnormalities ECG does not record all the heart’s electrical activity

44. Lecture 4

45. ECG helps to know?

46. How to calculate heart rate. heart rate define as the no of heart beats per minute.it can be determine by ECG VIA TWO RULES. Rule of 300 10 Second Rule

47. Rule of 300 Take the number of “big boxes” between neighboring QRS complexes, and divide this into 300. The result will be approximately equal to the rate. Although fast, this method only works for regular rhythms.

48. What is heart rate???????

49. Heart rate?

50. Heart rate ?

51. Rule of 10 sec As most EKGs record 10 seconds of rhythm per page, one can simply count the number of beats present on the EKG and multiply by 6 to get the number of beats per 60 seconds. This method works well for irregular rhythms

52. Rhythm. This is checked by the intervals between two R waves or two S waves. If the no of small or large sqs are equal between two R or S waves,, the rhythm is said to be normal. If not the rhythm is said to be irregular. Irregular rhythm is called Arrythmias .

53. Normal sinus rhythm

54. Sinus arrhythmia There is sinus rhythm , but the RR interval (heart rate) varies with respiration. Heart rate increase during inspiration and decrease during expiration.

55. Cardiac Rhythm: Supraventricular

56. Atrial flutter. When atrial rate is between 200 to 300 betas /min During atrial flutter AV node is not able to transmit all the impulses to ventricles so ventricular rate is 1/3 or ¼ of atrial rate. P wave is like saw tooth. Present is IHD , rheumatic heart disease.

57. ATRIAL FLUTTER Impulses travel in regular and circular course in atria – No interval between T and P.                                                                                                   

58. Atrial fibrillation. A totally irregular and rapid atrial rate in which there is a contraction of only small portion of atrial musculature. P waves replace by i rregular F waves , bcoz whole atria is not contracting. QRS complex and T waves r normal but rhythm is irregular.

59. ATRIAL FIBRILLATION                         Impulses have random pathways in atria.                                                                             

60. VENTRICULAR TACHYCARDIA Impulse originate at ventricular pacemaker – odd/wide QRS complex - often due to myocardial infarction , rate is about 120/ to 220/ min.

61. Ventricular fibrillation. Rapid ,irregular and ineffective contractions of small segments of ventricles is termed as ventricular fibrillation. Peripheral pulse is absent bcoz cardiac out put is zero.

62. VENTRICULAR FIBRILLATION hapazerd ventricular depolarization – ineffective at pumping – death within minutes                                                                                                   

63. Cardiac axis The flow of current from one point to another is representing by an arrow. This is called Vector. The direction of flow of current i.e the arrow point is always towards the positive direction. The range of cardiac axis is 0 to +90 degrees. Beyond this limit it is said to be deviated.

64. Vector Analysis

65. QRS axis. By near-consensus, the normal QRS axis is defined as ranging from -30 ° to +90 ° . -30 ° to -90 ° is referred to as a left axis deviation (LAD) +90 ° to +180 ° is referred to as a right axis deviation (RAD)

66. Axis deviation Deviation to R: increased activity in R vent. – obstruction in lung, pulmonary emboli, some heart disease Deviation to L: increased activity in L vent. – hypertension, aortic stenosis, ischemic heart disease

67. The quadrant approach

68. RAD Negative in I, positive in AVF