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ECG
- 1. ECG INTERPRETATION Dr. C.Kannan Post graduate Pediatrics MGMCRI
- 2. DISCUSSION • Anatomy ofconduction system of heart • ECG leads and attachment • Anatomy of ECG • Basic concepts • Cardiac Axis/Angle • Conduction abnormalities • Rhythm abnormalities • Abnormalities P, QRS and T waves • Exercises
- 3. ANATOMY OF CONDUCTIONSYSTEM
- 4. LEADS & ATTACHMENT Sixstandard leads • Attached to all four limbs (1,2,3,VR,VL& VF) • Right leg attachment has no value – act as earth • Looks the heart in vertical plane Six chest leads • Attached to chest (V1-6) • Looks the heart horizontal plane Attachment • Chest should be dry • Patient should be calm with zero muscular activity
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- 6. LEADS LOOKING @ LEADSLOOKING @ 1, 2 & VL Left lateral surface 3 & VF Inferior surface V1, V2 & VR Right ventricle V3 & V4 Septum & anterior wall of left ventricle V5 & V6 Anterior & lateral wall of left ventricle
- 7. ANATOMY OF ECG ECGmachine • Consists of stylus • Runs at standard rate of 25 mm/s • Over the ECG paper • Calibration • For signal of 1 millivolt • Stylus should move 1cm vertically up
- 8. ANATOMY OF ECG ECGpaper • Made up of squares • Small square • Each small square is 1 mm • Represents 0.04 seconds/40 milliseconds • large square • Made up of 5 small squares = 5 mm • Represents 0.2 seconds/200 milliseconds
- 9. HR FROM ECG •HR • 1500/No of small squares (or) • 300/No of large squares R-R INTERVAL (Large square) HEART RATE (Beats/Minute) 1 300 2 150 3 100 4 75 5 60 6 50
- 10. ANATOMY OF ECG •P wave – Atrial depolarisation • QRS wave – Ventricular depolarisation • T wave – Ventricular repolarisation • Note: Atrial repolarisation masked by vent. Depolarisation • Segments are straight lines / but not the intervals
- 11. ANATOMY OF ECG PRinterval • From beginning of P wave to the beginning of QRS wave • Time taken for the excitation to spread • From the SA node • Upto ventricular muscle • Should be called as PQ interval • Commonly used as PR interval • Duration: 3-5 small squares/120-220 ms
- 12. ANATOMY OF ECG QRScomplex • Duration is 120 ms/3 small squares • Low voltage QRS (<5 mm in limb leads/<10 mm in chest leads) • High voltage QRS (>20 mm in LL/>30 mm in CL) • Time taken for the excitation to • Spread through the ventricles • Represents • Only vent. depolarisation • No vent. Contraction • Contraction is proceeding during ST segment
- 13. ANATOMY OF ECG QTinterval • Represents both ventricular de/repolarisation • Should be less than 450 ms • Prolonged in electrolyte abnormalities/some drugs T wave • Repolarisation/relaxation of ventricles
- 14. BASIC CONCEPT • Ifelectrical signal passes towards the lead • Positive deflection • If electrical signal passes away from the lead • Negative deflection • If the electrical signal passes at right angle to lead • Equally positive and negative deflection
- 15. CARDIAC AXIS Normal cardiacaxis • If we see from front, depolarisation • Spreads through ventricles • From 11 o’ clock to 5 o’ clock • Electric signal passes towards the lead 2/away from VR • Hence lead 2 has more +ve deflection/ VR has –ve deflection
- 16. RIGHT AXIS DEVIATION •Any change in the heart or surrounding • Which shifts towards right side • Physiological: Short stature/obese individuals • Pathological: Any pathology leads to RVH
- 17. LEFT AXIS DEVIATION •Any change in the heart or surrounding • Which shifts the heart towards left side • Physiological: Thin/tall individuals • Pathological: Any pathology leads to LVH
- 18. CARDIAC ANGLE • Nomuch clinical significance • Normal cardiac angle is -30 to +90 degree • Left axis deviation is -30 to -90 degree • Right axis deviation is +90 to -90 degree • At birth +90 to +150 degree (N) • 1-8 years <90 degree (N)
- 19. HOW TO REPORTAN ECG ? • Rhythm • Rate • Conduction intervals (PR/QT interval) • Cardiac axis • Description of the QRS complexes • Description of ST segment and T wave
- 20. CONDUCTION ABNORMALITIES First degreeheart block • Delay in conduction b/w SA node to ventricle • So prolonged PR interval (>220 ms)
- 21. SECOND DEGREE BLOCK Wenckebach/mobitztype 1 • Progressive lengthening of PR interval and then • Failure of conduction of atrial beat followed by • Conducted beat with shorter PR interval • Again cycle continues
- 22. SECOND DEGREE BLOCK Mobitztype 2 • Constant PR interval • Occasionally P wave without subsequent QRS complex
- 23. THIRD DEGREE BLOCK •Complete heart block • Atrial beats are normal which is not conducted to the ventricle • Atrium and ventricle contracts irrespective to each other
- 24. RBBB • Right ventricledepolarises after the left • Impulse will be received from left ventricle • So 2 R waves in the form of RSR pattern in V1 lead • Deep S wave in V6 lead
- 25. LBBB • Left ventricledepolarises after the right • Impulse will be received from right ventricle • So 2 R waves in the form of W pattern in V1 lead • M pattern in V6 lead
- 26. RHYTHM ABNORMALITIES Sinus arrhythmia •Changes in the heart associated with respiration • Common in young people • One P wave per QRS complex • Constant PR interval • Progressive beat to beat change in RR interval
- 27. VENTRICULAR EXTRASYSTOLE • Anypart of heart depolarises earlier than it should and the • Accompanying beat is called extra systole • Occasionally vent. contracts on its own without atrial beat
- 28. ATRIAL FLUTTER • Atriumcontracts more than 300/min • Giving saw tooth appearance • 4 P waves per QRS complex • Ventricular contraction is perfect at 75/min
- 29. ATRIAL FIBRILLATION • NoP waves and irregular baseline • Normal shaped & Irregular QRS complexes • Normal T waves
- 30. VENTRICULAR TACHYCARDIA • Excitationspreads through abnormal path • Through ventricular muscle mass • Ventricle contract as a mass • Irrespective of atrium • In a very fast manner • Hence no P wave/T wave • Wide QRS complex (>200/min)
- 31. VENTRICULAR FIBRILLATION • Eachmuscle fibre contracts independently • No QRS complex • Totally disorganised
- 32. SUPRAVENTRICULAR TACHYCARDIA • Pwave present but superimposed on T wave • QRS complex have same shape throughout • Atrium beats more than 180/min
- 33. WOLF PARKINSON WHITESYNDROME • His bundle • Electrically connects atrium and ventricle • In WPW syndrome • An extra or accessory conducting bundle present • No AV node, hence no AV nodal delay • Impulse reaches ventricle very fast • Leads to premature excitation of ventricle • Short PR interval • QRS complex with slurred upstroke called delta wave
- 34. RAH • Peaked Pwave • Tricuspid stenosis • Pulmonary hypertension
- 35. LAH • Bifid Pwave • Mitral stenosis
- 36. RVH • Right axisdeviation • Tall R wave in V1 & V2 • Deep S in lead 1 • Inverted T waves in lead 2,3,VF and V1-3
- 37. LVH • Left axisdeviation • Tall R wave in V5 & V6 • Deep S in lead 3 • Inverted T waves in lead 1,VL and V5-6
- 38. ELECTROLYTE ABNORMALITIES • Hyperkalaemia •Peaked T waves • Disappearance of ST segment • Hypokalaemia • Flat T waves F/B U waves with • Prolonged QT interval • Hypocalcaemia • Prolonged QT interval • Hypercalcaemia • Short QT interval
- 39. REFERENCES • ECG madeeasy written by John R. Hampton
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- 44. 5. HOW TOREPORT THIS ECG ?
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