Ecg interpretation


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  • Cardiac conducting system
  • It’s vital to have a system in place to interpret the ECG.
  • Small square 0.04s; Large square 0.2s
  • It’s vital to have a system in place to interpret the ECG.
  • Can use lead II
  • The normal axis is around 60 degrees.
  • It’s vital to have a system in place to interpret the ECG.
  • Not very useful signs.
  • Short PR interval can be accessory pathway or can be normal
  • It’s vital to have a system in place to interpret the ECG.
  • It’s vital to have a system in place to interpret the ECG.
  • Tall = can be normal young man
  • T wave more than 10mm size= hyperkalemia
  • Long QT syndrome. Amiodarone, sotalol.
  • Long QT syndrome is associated with Torsades de pointes
  • Resiprocal: Reciprocal changes are simple the opposite deflection in an opposing lead, for example a posterior infarction causing ST depression in the anterior leads.
  • Mobitz type I, RBBB, LVH
  • Ecg interpretation

    1. 1. ECG interpretationDr Sudhir DevHouse OfficerDept. Of GP and Emergency Medicine
    2. 2. Objectives• Justify the reasons for performing an ECG• Develop a structured approach to interpretingan ECG• Practice interpreting ECGs
    3. 3. The ECG“The ECG (electrocardiogram) is a transthoracicinterpretation of the electrical activity of theheart.”
    4. 4. The ECGSA node -> atrial muscle -> AV node -> bundle of His ->Left and Right Bundle Branches -> Ventricular muscle
    5. 5. Lead Placement
    6. 6. EKG Distributions• Anteroseptal: V1, V2, V3, V4• Anterior: V1–V4• Anterolateral: V4–V6, I, aVL• Lateral: I and aVL• Inferior: II, III, and aVF• Inferolateral: II, III, aVF, and V5 and V6
    7. 7. Why perform an ECG?• It’s part of the admission bundle• Indicated by the patient’s symptoms- symptoms of IHD/MI- symptoms associated with dysrhythmias• Indicated by the patient’s examination findings- cardiac murmur
    8. 8. ECG Interpretation• Quality of ECG?• Rate• Rhythm• Axis• P wave• PR interval• QRS duration• QRS morphology• Abnormal Q waves• ST segment• T wave• QT interval
    9. 9. Quality of the ECG• Patient name• Date of the ECG• Is there any interference?• Is there electrical activity from all 12 leads?
    10. 10. Calibration• Standard calibration of the ECG is 10mm/mV and normal speed 25mm/sec.At this calibration, 1 miliVolt calibration signal is expected to produce arectangle of 10 mm height and 5 mm width.• When ECG waves are tall, the R or S waves may extend into the QRScomplexes above or below them. To prevent this superimposition, the wholeECG may be calibrated at 5mm/mV .LOW VOLTAGELow voltage of the limb leads is present when the amplitude of the QRScomplex in each of the three standard limb leads (I, II, and III) is <5 mm . Lowvoltage of all leads is diagnosed when the average voltage in the limb leads is<5 mm and the average voltage in the chest leads is <10 mm.
    11. 11. An example of correct calibration at 10 mm/mV and speed of 25 mm/sec : Thecalibration signal is a rectangle making 90 degrees of angles.
    12. 12. ECG interpretation• Quality of ECG?• Rate• Rhythm• Axis• P wave• PR interval• QRS duration• QRS morphology• Abnormal Q waves• ST segment• T wave• QT interval
    13. 13. Rate• The 6 Second Rule: All but very slow heart rates can be determined by countingthe number of cycles that occur within 6 seconds, and then multiplying thatnumber by 10.• The rule of 300 : 300/number of big squares between R waves• Rate is either:- Normal– Bradycardia – HR < 40bpm– Tachycardia HR > 120bpm
    14. 14. Rate
    15. 15. Rhythm• Look for:• Are there P waves?• Are they regular?• Does one precede every QRS complex?Rythm could either be of sinus or non sinus in origin . Having P wave is sinus origin.Without P wave or buried with preceeding T wave is either Venticular or Supraventricularorigin.
    16. 16. AxisDefinition:the mean direction of electrical forces in the frontal plane ( limb leads) as measuredfrom the zero reference point (lead 1)Normal valuesP wave: 0 to 75 degreesQRS complex: -30 to 90 degressT wave: QRS-T angle <45 degrees frontal or <60 degrees precordial
    17. 17. The Quadrant Approach• QRS up in I and up in aVF = Normal
    18. 18. AxisPositive in I and II= NORMALPositive in I andnegative in II = LADNegative in I andpositive in II = RAD
    19. 19. D/D of Right Axis Deviation (RAD)• Differential diagnosis Right Ventricular Hypertrophy (RVH) — most common• Left Posterior Fascicular Block (LPFB) — diagnosis of exclusion• Lateral and apical MI• Acute Right Heart Strain, e.g. acute lung disease such as pulmonary embolus• Chronic lung disease, e.g. COPD• Dextrocardia• Ventricular pre-excitation (WPW) — LV free wall accessory pathway• Ventricular ectopy• Hyperkalemia• Sodium-channel blockade, e.g. tricyclic toxicity• Normal in infants and children• Normal young or slender adults with a horizontally positioned heart can alsodemonstrate a rightward QRS axis on the ECG.
    20. 20. D/D ofLeft Axis Deviation (LAD)• left ventricular hypertrophy (LVH)• Left Anterior Fascicular Block (LAFB) — diagnosisof exclusion• LBBB• inferior MI• ventricular ectopy• paced beats• Ventricular pre-excitation (WPW)
    21. 21. ECG interpretation• Quality of ECG?• Rate• Rhythm• Axis• P wave• PR interval• QRS duration• QRS morphology• Abnormal Q waves• ST segment• T wave• QT interval
    22. 22. P wave• The P wave is the first positive deflection on the ECG• It represents atrial depolarisationCharacteristics of the Normal Sinus P Wave• Morphology• Smooth contour• Monophasic in lead II• Biphasic in V1• Axis• Normal P wave axis is between 0° and +75°• P waves should be upright in leads I and II, inverted in aVR• Duration• < 120 ms• Amplitude• < 2.5 mm in the limb leads,• < 1.5 mm in the precordial leads
    23. 23. P wave abnormalitiesCommon P wave abnormalities include:• P mitrale (bifid P waves), seen with left atrialenlargement.• P pulmonale (peaked P waves), seen with right atrialenlargement.• P wave inversion, seen with ectopic atrial andjunctional rhythms.• Variable P wave morphology, seen in multifocal atrialrhythms.
    24. 24. P mitrale
    25. 25. P pulmonale
    26. 26. PR interval• The PR interval is the time from the onset of the P wave to thestart of the QRS complex.• It reflects conduction through the AV node.• Start of P wave to start of QRS complex• Normal = 0.12 - 0.2 seconds (3-5 small squares)• Decreased = can indicate an accessory pathway• Increased = indicates AV block (1st/2nd/3rd)
    27. 27. ECG interpretation• Quality of ECG?• Rate• Rhythm• Axis• P wave• PR interval• QRS duration• QRS morphology• Abnormal Q waves• ST segment• T wave• QT interval
    28. 28. QRS complexMain Features to Consider• Width of the complexes: Narrow versus broad.• Voltage (height) of the complexes.• Spot diagnoses: Specific morphology patterns that are important torecognise.• Normal = <0.12 seconds• Narrow complexes (QRS < 100 ms) are supraventricular in origin.• Broad complexes (QRS > 100 ms) may be either ventricular in origin, ormay be due to aberrant conduction of supraventricular complexes (e.g.due to bundle branch block, hyperkalaemia or sodium-channel blockade)
    29. 29. Low Voltage QRS• Low Voltage• The QRS is said to be low voltage when:• The amplitudes of all the QRS complexes inthe limb leads are < 5 mm; or• The amplitudes of all the QRS complexes inthe precordial leads are < 10 mm
    30. 30. QRS complex• Is there LVH?• Probably the most commonly used are the Sokolov-Lyon criteria (S wavedepth in V1 + tallest R wave height in V5-V6 > 35 mm).>35mm is suggestive of LVH
    31. 31. Q waves• Q waves are allowed in V1, aVR & III• Pathological Q waves can indicate previous MI
    32. 32. ECG interpretation• Quality of ECG?• Rate• Rhythm• Axis• P wave• PR interval• QRS duration• QRS morphology• Abnormal Q waves• ST segment• T wave• QT interval
    33. 33. ST segment• The ST segment is the flat, isoelectric section of the ECG between the end of the Swave and the beginning of the T wave.• It represents the interval between ventricular depolarisation and repolarisation.• The most important cause of ST segment abnormality (elevation or depression) ismyocardial ischaemia / infarction.• ST depression (upsloping, horizontal and downsloping)- downsloping or horizontal = ABNORMAL• ST elevation- infarction- pericarditis (widespread)
    34. 34. ST segment depression
    35. 35. ST segment elevation
    36. 36. T wave• Small = hypokalaemia• Tall = hyperkalaemia• Inverted/biphasic = ischaemia/previous infarct• Hyperkalemia: Potassium reduces myocardial excitability, withdepression of pacemaking and conducting tissues.• K+ >5.5 meq/l is a/w repolarization abnormalities causing peaked T waves(earliest sign of hyperkalemia)• K+>6.5 a/w progressive paralysis of artia , ECG shows wide and flat Pwave, incerase PR and P wave eventually dissapear.• K+ more than 7 causes conduction abnormalities and bradycardia andeventually asystole.
    37. 37. T wave
    38. 38. T wave
    39. 39. T wave
    40. 40. QT interval• Start of QRS to end of T wave• Needs to be corrected for HR• Normal QTc = < 400ms• Long QT can be genetic or iatrogenic
    41. 41. QT interval
    42. 42. BlocksAV blocksFirst degree blockPR interval fixed and > 0.2 secSecond degree block, Mobitz type 1PR gradually lengthened, then drop QRSSecond degree block, Mobitz type 2PR fixed, but drop QRS randomlyType 3 blockPR and QRS dissociated
    43. 43. Some important ECG examples
    44. 44. Lateral MIReciprocal changes
    45. 45. Inferolateral MIST elevation II, III, aVFST depression in aVL, V1-V3 are reciprocal changes
    46. 46. Anterolateral / Inferior IschemiaLVH, AV junctional rhythm, bradycardia
    47. 47. Left Bundle Branch BlockMonophasic R wave in I and V6, QRS > 0.12 secLoss of R wave in precordial leadsQRS T wave discordance I, V1, V6Consider cardiac ischemia if a new finding
    48. 48. Right Bundle Branch BlockV1: RSR prime pattern with inverted T waveV6: Wide deep slurred S wave
    49. 49. First Degree Heart Block, Mobitz Type I (Wenckebach)PR progressively lengthens until QRS drops
    50. 50. Supraventricular TachycardiaNarrow complex, regular; retrograde P waves, rate <220Retrograde P waves
    51. 51. Right Ventricular Myocardial InfarctionFound in 1/3 of patients with inferior MIIncreased morbidity and mortalityST elevation in V4-V6 of Right-sided EKG
    52. 52. Ventricular Tachycardia
    53. 53. Prolonged QTQT > 450 msInferior and anterolateral ischemia
    54. 54. Second Degree Heart Block, Mobitz Type IIPR interval fixed, QRS dropped intermittently
    55. 55. Acute Pulmonary EmbolismSIQIIITIII in 10-15%T-wave inversions, especially occurring ininferior and anteroseptal simultaneouslyRAD
    56. 56. Wolff-Parkinson-White SyndromeShort PR interval <0.12 secProlonged QRS >0.10 secDelta waveCan simulate ventricular hypertrophy, BBB and previous MI
    57. 57. HypokalemiaU wavesCan also see PVCs, ST depression, small T waves
    58. 58. THANK YOU