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Basic ECG Interpretation.pptx
- 1. Basic ECG Interpretation in the ED
- 2. Learning Objectives. • Interpret a basic 12 lead ECG. • Recognize common cardiac arrhythmia's • Recognize STEMI’s and STEMI equivalents. • Recognize myocardial ischemia. • Recognize common heart blocks.
- 4. 12 Lead ECG – Standard Position 4 Limb Leads •Right Arm & Leg •Left Arm and Leg 6 Chest Leads •Placement from 4th intercostal space to the 5th intercostal space laterally
- 6. 12 Lead ECG Posterior Leads • Useful in the diagnosis of posterior infarcts • 3 extra leads on the posterior chest • V7– 9 • V7 (left posterior axillary line) • V8 (tip of scapula) • V9 (left paraspinal region)
- 8. ECG Interpretation • Standard paper speed is 25 mm/sec • 1 small square equals 0.04 seconds • Rough estimation of heart rate from rhythm strip • 300 bpm divided by the number of large squares
- 9. Components of the ECG Complex • P wave • QRS Complex • T wave • PR Interval • ST Segment • QT Interval
- 11. P Wave Atrial Contraction • 2 -3 mm high • 2 -3 small squares (duration) • 0.06 – 0.12 seconds (duration)
- 12. PR Interval Transit time from sinus node to the ventricles • 3 – 5 small squares (duration) • 0.012 – 0.20 seconds (duration)
- 13. QRS Complex Ventricular depolarization / contraction • 5 -30 mm height • 1.5 – 2.5 square (duration) • 0.06 – 0.10 seconds (duration)
- 14. QT Interval • Distance from beginning of Q wave to the end of the T wave • Represents ventricular systole (activation and recovery) • 9 – 11 small squares (duration) • 350 – 450 ms (duration)
- 15. T Wave Represents ventricular repolarization T waves are normally upright in most leads Exceptions are aVR and V1
- 17. Heart Rates Normal Heart Rate (60 – 100 bpm) Tachycardia (More than 100 bpm) Bradycardia (Less than 60 bpm)
- 18. Sinus Rhythm • Narrow complex, regular rhythm • QRS complex follows every P wave
- 19. Sinus Rhythm
- 20. Sinus Arrhythmia • Narrow complex, irregular rhythm • QRS complex follows every P wave • Beat to beat variability of the QRS complex from respiration
- 21. Sinus Arrhythmia
- 22. Atrial Fibrillation • Arrhythmia characterized by irregular beating of the atrial chambers of the heart • Irregularly irregular rhythm • No discernable P wave activity • Can present with rapid ventricular response or a controlled ventricular response
- 27. Atrial Flutter • Re-entry circuit within the right atrium • Regularly regular rhythm • No discernable P wave activity • Presence of flutter waves (saw tooth pattern waves)
- 28. Atrial Flutter
- 29. Atrial Flutter
- 30. AVNRT • AV Nodal Re-entrant Tachycardia (commonly known as SVT) • SVT (Supraventricular Tachycardia) • Functional re-entry circuit within AV node • Regular narrow complex tachycardia (140 – 280 bpm)
- 31. AVNRT
- 32. Ventricular Tachycardia • Rapid tachycardia arising from the ventricles • Regular broad complex tachycardia • Rate is greater than 120 bpm • More than 3 wide QRS complexes in a row • 2 types • Monomorphic (same amplitude) • Polymorphic (variable amplitude – also known as “torsade's de pointes”)
- 33. Monomorphic VT Common Causes • Ischemic Heart Disease • Dilated Cardiomyopathy • Hypertrophic Cardiomyopathy
- 34. Monomorphic VT
- 35. Polymorphic VT Common Causes • Ischemia • Drugs • Prolongation of the QT Interval • Electrolyte Disturbance (Hypokalemia)
- 36. Polymorphic VT
- 37. Ventricular Fibrillation • Chaotic irregular deflections of variable amplitude • No identifiable P waves, QRS complexes or T waves • Rate variable between 150 – 500 per minute • Amplitude decreases with time (coarse to fine)
- 39. STEMI’s and STEMI Equivalents
- 40. How to measure ST Elevation & Depression ST elevation and depression is measured from the J point. This is the junction of the QRS complex and the ST segment. Elevation or depression is measured from this point to the baseline.
- 42. Characteristics – Ischemic ST Elevation
- 44. Inferior STEMI (II,III,aVF - ST Elevation)
- 45. Lateral STEMI (I,aVL,V5-6 - ST Elevation)
- 46. Posterior STEMI (ST Depression & Upright T Waves V1-3)
- 47. Posterior STEMI (Posterior V7-9 - ST Elevation)
- 48. De Winters Waves • Anterior STEMI equivalent • Associated with LAD occlusion • Prominent symmetrical T waves in precordial leads • Upsloping ST depression in the precordial leads
- 49. De Winters Waves
- 50. Wellen’s Syndrome • Biphasic or deeply inverted T waves in V2-3 with a history of recent chest pain that has resolved. • Highly specific for critical stenosis for the LAD (left anterior descending artery).
- 52. Sgarbossa Criteria (Original) • Allows diagnosis of infarction in presence of LBBB or paced rhythm • Concordant ST elevation > 1 mm in leads with positive QRS complex (score of 5) • Concordant ST depression > 1 mm in leads V1-3 (score of 3) • Excessive discordant ST elevation in 1 lead as defined as more than 5 mm in leads with negative QRS complex (score of 2) • Score > 3 (Sensitivity 36%, Specificity 90%) • Use internet to check the criteria as difficult to remember
- 55. ST Depression – Ischemia (V4-6)
- 56. ST Depression – Ischemia (II,III,aVF, V4-6)
- 57. Benign Early Repolarization • Normal variant, usually seen in younger patients • ST segment elevation – elevated J point • Notch at the end of the QRS complex • ST segment is concave up • Absence of reciprocal ST segment changes
- 59. Pericardial Effusion • Sinus tachycardia • Low voltage • Electrical alternans • Alternating QRS complex height • Heart swinging back and forward in fluid filled pericardium • Best seen in lateral leads (I, aVL, V4-6)
- 60. Low Voltage (Electrical impulses do not travel through fluid well)
- 62. Left Ventricular Hypertrophy • Must have voltage and non-voltage criteria • Voltage Criteria • Sokolov – Lyon Criteria • S wave depth in V1 and R wave height in V5 or 6 greater than 35 mm • Non-voltage Criteria • ST depression and T wave inversion in left sided leads (II, III, aVF, V5-6)
- 65. Left Bundle Branch Block (LBBB) • Prolonged QRS complex (more than 120 mS) • Dominant S wave in V1 • Broad notched R wave
- 66. Left Bundle Branch Block (LBBB)
- 67. Right Bundle Branch Block (RBBB) • Prolonged QRS complex greater than 120 ms • RSR pattern in V1-3 (M shaped pattern)
- 68. Right Bundle Block (RBBB)
- 69. First Degree Heart Block • Delay without interruption in conduction from atria to ventricles • Prolonged PR interval greater than 200 ms • PR interval greater than 5 small squares
- 70. First Degree Heart Block
- 71. Second Degree Heart Block Mobitz 1 • Wenckebach Heart Block • PR interval progressively increases followed by a dropped QRS complex
- 72. Second Degree Block – Mobitz 1
- 73. Second Degree Heart Block Mobitz 2 Mobitz 2 • PR interval is fixed, but there are dropped beats • Clarify by the number of dropped beats (2:1, 3:1)
- 74. Second Degree Heart Block – Mobitz 2
- 75. Third Degree Heart Block • Complete Heart Block • AV dissociation • P waves and QRS complexes and completely unrelated
- 76. Third Degree Heart Block
- 77. Revision Questions • Describe the findings on the following ECG’s • The answer will be shown on the slide following the ECG
- 79. ECG Number 1 • Irregularly Irregular Rhythm • Narrow Complex Tachycardia (Rate – approximately 150 bpm) • No P wave activity seen • Diagnosis - Atrial Fibrillation
- 81. ECG Number 2 • P waves and QRS complexes with no relation between them • AV dissociation • Diagnosis - Complete (3rd Degree) Heart Block
- 83. ECG Number 3 • ST Elevation - Leads II, III, aVF • Reciprocal ST Depression – Leads V1-2, 1, aVL • Diagnosis - Inferior STEMI
- 85. ECG Number 4 • Chaotic irregular disorganized rhythm • No P wave or QRS activity • Diagnosis – Ventricular Fibrillation