ECG Basics, and detailing individual waves

Ecg basics

1. ECG BASICS AND ARRHYTHMIA RECOGNITION Dr. Mohammed Thanveer A

2. 'HOW TO RECORD AN ECG' Electrodes are placed on chest and limb of the patient To know heart’s complete electrical activity 12 electrodes are needed . 6-limb leads(vertical plane),6-chest leads (horizontal plane) 6 limb leads [1,2,3,vl,vf,vr],6 chest leads [v1,v2,v3,v4,v5,v6]

3. CARDIAC CONDUCTION SYSTEM Heart’s conduction system is the network of nodes,speacialized cells and electrical signals that keep your heart beating. Two types of cells Control your heartbeat 1.conducting cells-carry electrical signals 2.Muscle cells(myocytes)-which control Heart’s contractions.

4. PARTS OF HEART’S CONDUCTION SYSTEM Sinoatrial node Atrioventricular node Bundle of his Purkinje fibres

5. ECG WAVES

6. ECG RATE INTERPRETATION Standardisation is 25mmsec At this standardisation the rhythm strip consists of 250 small square=50 large square =10sec Therefore the rhythm strip recorded for 1minute comprises of 1500 small squares=300 large squares=1 minute

7. Methods of calculating rate There are three methods to calculate rate 1.large square method 2.small square method 3.r wave method

8. LARGE SQUARE METHOD

9. SMALL SQUARE METHOD

10. R wave method Number of r wave *6

11. ECG RHYTHM EVALUATION Rhythm is usually recorded at lead 2 STEP 1-Rate (tachy or Brady) STEP 2-By RR interval STEP 3-QRS MORPHOLOGY ( wide or narrow qrs ) STEP 4- ‘P’ WAVE (Absent or present ) Absent (Sinus arrest ,AF) Present (Morphology and pr interval may suggest sinus ,atrial,junctional or even retrograde ) STEP 5-Relationship between p wave and QRS complex.

12. P WAVE AND ITS ABNORMALITIES P wave represents the first positive deflection on the ecg It represents atrial depolarisation Normal duration is <120ms or <3 small squares P wave is upright in leads 1,2 and inverted in avR

13. P’ pulmonale and p’ mitrale

14. PR INTERVAL PR interval is the time of onset of P wave to the start of QRS complex. The normal duration is 120-200ms (3-5 small squares) If PR interval is >200ms first degree heart block is Said to be present. If PR interval is <120ms Suggest preexcitation (Presence of accessory pathway between atria and ventricles),or AV nodal (junctional) rhythm.

15. INVERTED P WAVES Global P wave inversion - dextrocardia Human errors

16. VARIABLE ‘p’WAVE MORPHOLOGY If >-3 p wave morphology-multifocal atrial rhythm If >-3p wave morphology with >100bpm-multifocal atrial tachycardia.

17. QRS COMPLEX NORMAL QRS WIDTH IS 40ms-120ms NARROW QRS<40ms IS SUPRAVENTRICULAR IN ORIGIN BROAD QRS>120ms MAY BE VENTRICULAR IN ORIGIN (I.e, due to bundle branch block,hyperkalemia(when k+>8),Sodium channel blocking agents like tricyclic anti depressants,Wolf Parkinson’s white syndrome,hypothermia

18. EXAMPLES OF NARROW QRS COMPLEX Sinus rhythm Svt Atrial flutter

19. Examples of broad QRS complex Ventricular tachycardia Right bundle branch block BRUGADA syndrome Left bundle branch block Wolf parkinson white syndrome

20. Ventricular tachycardia-broad QRS complex with no Visible ‘p’waves Polymorphic vt

21. RIGHT BUNDLE BRANCH BLOCK RSR’ pattern in v1 to v3 Slurred S wave in v6

22. DD OF RBBB BRUGADA SYNDROME: ECG pattern-coved type st elevation and t wave inversion in v1 to v3 It is generally of three types -type 1,2,3 ( type 1 most common ) It is associated with malignant ventricular tachycardia It can cause sudden unexpected nocturnal death syndrome

23. LEFT BUNDLE BRANCH BLOCK V1-prominent ‘s’ wave V6-broad notched ‘r’ wave

24. WOLF PARKINSON WHITE SYNDROME QRS prolongation >120ms DELTA WAVE:slurring slow rise of initial portion of QRS

25. ‘T’ WAVE CHARACTERISTICS UPRIGHT IN ALL LEADS EXCEPT AVR AND V1 Happens during ventricular repolarisation. Duration -160ms to 250ms ITS DURATION RELATES TO QT INTERVAL.

26. ‘T’ WAVE ABNORMALITIES PEAKED ‘T’ WAVES -Tall ,narrow Symmetrically peaked T waves are characteristic of HYPERKALEMIA *T wave greater than the half the size of QRS complex is often considered indicative of peaked T wave .

27. BROAD T WAVES *Broad asymmetric T waves are seen in Early stages of ST elevation MI *They are associated with prinzmetal angina

28. INVERTED ‘T’ WAVES Normal in children Persistent Juvenile T wave pattern MI Bundle branch block Ventricular hypertrophy Pulmonary embolism Hypertrophic cardiomyopathy In some females inverted in v1-v3

29. Paediatric ‘T‘ wave Inverted T waves in precocial leads v1 to v3 is normal in children

30. Persistent Juvenile ‘T’ wave pattern These are asymmetrical and shallow <3mm And limited to leads v1 to v3

31. ST SEGMENT It represents the interval between Ventricular depolarisation and repolarisation. It is a flat isoelectric section of ecg Between the end of S wave and the beginning of T wave Duration-80ms to 120ms

32. J POINT J point is the junction between termination of QRS complex and Beginning of ST segment.

33. CAUSES OF ST SEGMENT ELEVATION Acute MI Coronary vasospasm Pericarditis Left ventricular hypertrophy Ventricular aneurysm BRUGADA syndrome Raised intracranial pressure Benign early re polarisation LBBB Takotsubu cardiomyopathy

34. MORPHOLOGY OF ELEVATED ST SEGMENT IN MI

35. MORPHOLOGY OF ST ELEVATION IN OTHER CONDITIONS

36. CAUSES OF ST SEGMENT DEPRESSION NSTEMI Reciprocal change in stemi posterior wall mi Digoxin effect

37. ST SEGMENT DEPRESSION

38. ST SEGMENT DEPRESSION IN OTHER CONDITIONS

39. MYOCARDIAL ISCHEMIA T WAVE INVERSION IN MI OCCURS BASED ON THE ANATOMICAL LOCATION OF THE INFARCT OR ISCHEMIA Lateral wall MI -1,avl,V5-6 Extensive Anterior wall MI-V2 to v6 Inferior wall MI-2,3,avf Dynamic T wave inversion -Seen in acute MI Fixed T wave inversion-Seen following infarction Usually in association with Pathological q waves.

40. Inferior WALL T wave inversion - ischemia

41. Inferior T wave inversion with Q waves -prior MI

42. T wave inversion in lateral leads - acute ischemia

43. Anterior T wave inversion With q waves -recent MI

44. T wave inversion in LVH Produces T wave inversion lat leads 1,avl And v5-v6

45. T wave inversion in RVH and pulmonary embolism In leads v1-v3 and inferior leads 2,3,avf

46. Pulmonary embolism also produces T wave inversion in Lead 3 as Part of S1,Q3,T3 pattern

47. T wave inversion in HCM It produces deep inverted T waves in all precordial leads

48. BIPHASIC T WAVES Occurs in MI ,hypokalemia

49. ‘U’ wave-hypokalemia Global T wave flattening and prominent ‘u’ wave in Ant leads v2and v3

50. ARRHYTHMIA RECOGNITION

51. SUPRAVENTRICULAR TACHYCARDIA Types of Svt 1.atrial fibrillation 2.atrial flutter 3.atrial tachycardia 4.av nodal reentrant tachycardia(m/c) 5.av reentrant tachycardia

52. ATRIAL ARRHYTHMIA 1.Premature atrial contractions *It is a premature beat arising from ectopic peacemaking tissue within the atria *There is a abnormal p wave followed by normal QRS complex

53. ATRIAL FIBRILLATION It is a supraventricular tachyarrythmia characterised by uncoordinated atrial activation and consequently ineffective atrial contractions. *irregularly irregular rhythm *no p waves *absense of isoelectric baseline *QRS complex <120ms

54. ATRIAL FLUTTER *Atrial activity at 300bpm *loss of isoelectric baseline *saw tooth pattern of waves are noted

55. Av nodal reentrant tachycardia

56. VENTRICULAR ARRYTHMIAS Premature ventricular contractions *broad QRS complex >120ms *discordant st and T wave changes

57. VENTRICULAR TACHYCARDIA Monomorphic VT *all QRS complex are wide and looks the same *around 150-250bpm Example :old MI

58. Polymorphic VT There are multiple ventricular foci *QRS complex varying in amplitude axis and duration *The m/c/c of polymorphic vt is myocardial ischemia or infarction

59. TORSADES DE POINTES It is a specific form of polymorphic ventricular tachycardia in which the QRS complex twist around the isoelectric line

60. HEART BLOCKS THREE TYPES 1st degree 2nd degree -Mobitz type 1 and Mobitz type 2 3rd degree

61. First degree heart block *PR interval is > .20 sec (I,e. > 5 small squares) * all p waves are conducted * usually asymptomatic

62. Second degree heart block TYPE 1 MOBITZ * progressive prolongation of PR interval until a beat is dropped

63. Mobitz type 2 * Intermittent non conducted p wave without PR prolongation

64. COMPLETE HEART BLOCK (3rd degree) *No atrial impulses conducted to ventricles * p wave and QRS complex are independent * atrial rate more than ventricular rate