Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

ECG interpretation: the basics


Published on

Presentation to participants undertaking the: Critical Care Transition Program at ACT Health, 2008

  • nice
    Are you sure you want to  Yes  No
    Your message goes here
  • Thank you!
    Are you sure you want to  Yes  No
    Your message goes here
  • very informative
    Are you sure you want to  Yes  No
    Your message goes here
  • I have recently produced a site on healthcare resources.

    One of these resources is an ECG Interpretation and Rhythm Recognition resource, which is available both as a e-book and also as a paperback.

    I truly believe that this resource would benefit your readers / users.

    The url fo the site is

    The url to the specific ECG Interpretation and Rhythm Recognition resource is

    I would like you to put a link to these resources to your site.

    Again I believe this resource would be a great benefit to your readers / users.

    Tell me what you think, I really appreciate your time and consideration.

    Jamie BIsson
    Are you sure you want to  Yes  No
    Your message goes here

ECG interpretation: the basics

  1. 1. ECG INTERPRETATION: the basics Jamie Ranse Critical Care Education Coordinator Staff Development Unit ACT Health
  2. 2. Overview <ul><li>Conduction Pathways </li></ul><ul><li>Systematic Interpretation </li></ul><ul><li>Common abnormalities in Critical Care </li></ul><ul><ul><li>Supraventricular arrhythmias </li></ul></ul><ul><ul><li>Ventricular arrhythmias </li></ul></ul>
  3. 3. Conduction Pathways
  4. 4. <ul><li>P wave = atrial depolarisation. </li></ul><ul><li>PR Interval = impulse from atria to ventricles. </li></ul><ul><li>QRS complex = ventricular depolarisation. </li></ul><ul><li>ST segment = isoelectric - part of repolarisation. </li></ul><ul><li>T wave = usually same direction as QRS - ventricular repolarisation. </li></ul><ul><li>QT Interval = This interval spans the onset of depolarisation to the completion of repolarization of the ventricles. </li></ul>Conduction Pathways
  5. 5. Interpretation
  6. 6. <ul><li>Rate = Number of P’s (atrial) R’s (ventricular) per minute (6 second [30 squares] X 10 = minute rate). </li></ul><ul><li>Rhythm = Regular or irregular. Map P-P and R-R intervals. </li></ul>Interpretation P rate: 8 x 10 = 80 R rate: 8 x 10 = 80
  7. 7. <ul><li>3. P wave = present, 1 per QRS, shape, duration, voltage. </li></ul><ul><li>4. P-R interval = length (0.12 - 0.2 sec = <1 big square), isoelectric. </li></ul>Interpretation
  8. 8. <ul><li>5. QRS = duration (0.06 - 0.10 ) , voltage, q or Q waves </li></ul><ul><li>6. ST Segment = shape, isoelectric with PR segment </li></ul>Interpretation
  9. 9. <ul><li>7. T wave = shape, direction </li></ul><ul><li>8. QT interval = length (R-R/2 or QT c <0.40 sec) </li></ul>Interpretation
  10. 10. Abnormalities: Supraventricular arrhythmias <ul><li>Atrial Fibrillation </li></ul><ul><li>Atrial Flutter </li></ul><ul><li>Supraventricular Tachycardia (SVT) </li></ul><ul><li>Premature Ventricular Complexes (PACs) </li></ul>Abnormalities: Ventricular arrhythmias
  11. 11. Conduction Pathways Supraventricular Narrow QRS complex Ventricular Wide QRS complex
  12. 12. Abnormalities: atrial fibrillation Rhythm: Irregular Rate: A: 350 – 650; V: varies P: poorly defined P-R: N/A QRS: narrow complex S-T: normal T: normal Q-T: normal
  13. 13. Abnormalities: atrial flutter Rhythm: Regular / Irregular Rate: A: 220 – 430; V: <300 (2:1, 3:1 or sometimes 4:1) P: Saw toothed appearance P-R: N/A QRS: narrow complex S-T: normal T: normal Q-T: normal
  14. 14. Abnormalities: supraventricular tachycardia (SVT) <ul><li>Rhythm: Regular </li></ul><ul><li>Rate: >100 </li></ul><ul><li>P: not visible </li></ul><ul><li>P-R: not defined </li></ul><ul><li>QRS: narrow complex </li></ul><ul><li>S-T: depression (sometimes) </li></ul><ul><li>T: normal </li></ul><ul><li>Q-T: prolonged (sometimes) </li></ul>
  15. 15. Abnormalities: premature ventricular complexes
  16. 16. Examples
  17. 17. Examples
  18. 18. ECG INTERPRETATION: 12 Lead
  19. 19. Overview <ul><li>Lead Placement </li></ul><ul><li>Axis </li></ul><ul><li>Common abnormalities in Critical Care </li></ul><ul><ul><li>Heart block </li></ul></ul><ul><ul><li>Bundle branch blocks </li></ul></ul><ul><ul><li>Life threatening arrhythmias </li></ul></ul>
  20. 20. Lead Placement <ul><li>V1 = 4th ICS right sternum </li></ul><ul><li>V2 = 4th ICS left sternum </li></ul><ul><li>V3 = midway between V2 and V4 </li></ul><ul><li>V4 = 5th ICS midclavicular </li></ul><ul><li>V5 = between V4 and V6 anterior auxiliary line </li></ul><ul><li>V6 = midauxillary line lateral to V4 and V5 </li></ul>
  21. 21. Lead Placement <ul><li>Electrical activity towards = ↑ </li></ul><ul><li>Electrical activity away = ↓ </li></ul>
  22. 22. Lead Placement
  23. 23. Axis <ul><li>The direction of an ECG waveform in the frontal plane measured in degrees </li></ul><ul><li>Represents the flow of the majority of electrical activity </li></ul><ul><li>Normally the QRS complex is measured </li></ul>
  24. 24. Axis <ul><li>Each lead has its own axis </li></ul>
  25. 25. Lead Placement <ul><li>Standard Leads (bipolar) </li></ul><ul><li>I - lateral wall </li></ul><ul><li>II - inferior wall </li></ul><ul><li>III - inferior wall </li></ul><ul><li>Augmented leads (unipolar) </li></ul><ul><li>aVR - no mans land </li></ul><ul><li>aVL - lateral wall </li></ul><ul><li>aVF - inferior wall </li></ul><ul><li>Chest Leads (unipolar) </li></ul><ul><li>V1 - septal wall </li></ul><ul><li>V2 - septal wall </li></ul><ul><li>V3 - anterior wall </li></ul><ul><li>V4 - anterior wall </li></ul><ul><li>V5 - lateral wall </li></ul><ul><li>V6 - lateral wall </li></ul>
  26. 26. Lead Placement No-mans land, inferior , lateral , anterior , septal ,
  27. 27. Abnormalities: bundle branch blocks <ul><li>QRS widened, greater than 0.12 secs </li></ul><ul><li>Change in axis </li></ul><ul><li>Difficult to interpret ECG </li></ul><ul><li>Right or Left </li></ul><ul><li>Normal P wave </li></ul><ul><li>Followed by a T wave </li></ul>
  28. 28. Abnormalities: right bundle branch blocks <ul><li>Indicates conduction problems in the right side of the heart </li></ul><ul><li>May be normal in healthy people </li></ul><ul><li>R wave in V1, ie two R waves in V1 </li></ul><ul><li>Q wave in V6 </li></ul><ul><li>Lead V1 cats ears </li></ul>
  29. 29. Abnormalities: left bundle branch blocks <ul><li>Always indicates heart disease, usually of the left side of the heart </li></ul><ul><li>Hard to interpret an ECG with LBBB </li></ul><ul><li>Lead V1 Q wave and an S wave </li></ul><ul><li>Lead V6 an R wave followed by another R wave </li></ul><ul><li>Lead V6 Rabbit ears </li></ul>
  30. 30. Abnormalities: heart block <ul><li>SA block (exit block) </li></ul><ul><li>1 st degree AV block </li></ul><ul><li>2 nd degree AV block </li></ul><ul><ul><li>Wenckeback (type I) </li></ul></ul><ul><ul><li>Mobitz (type II) </li></ul></ul><ul><li>3 rd degree AV block </li></ul>
  31. 31. Abnormalities: heart block – SA block
  32. 32. Abnormalities: heart block – 1 st degree AV
  33. 33. Abnormalities: heart block – 2 nd degree AV <ul><li>Wenkeback </li></ul><ul><li>Mobitz </li></ul>
  34. 34. Abnormalities: heart block – 3 rd degree AV
  35. 35. Abnormalities: life threatening arrhythmias <ul><li>Ventricular Tachycardia </li></ul><ul><li>Ventricular Fibrillation </li></ul><ul><li>Asystole </li></ul>
  36. 36. Abnormalities: life threatening arrhythmias - VT
  37. 37. Abnormalities: life threatening arrhythmias - VF
  38. 38. Abnormalities: life threatening arrhythmias – Asystole
  39. 39. Examples
  40. 40. Examples