ECG

832 views
576 views

Published on

0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
832
On SlideShare
0
From Embeds
0
Number of Embeds
3
Actions
Shares
0
Downloads
36
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

ECG

  1. 1. TheElectrocardiogram ECG1
  2. 2. 2ECG Shows electrical pattern generated by heart as it’s activated from atrium to ventricle  Muscle undergoes depolarization and repolarization during each cardiac cycle Leadsprovide us with 3D vectors that indicate direction of depolarization  Looking at different projections in different directions of body
  3. 3. 3 Cardiac depolarization spreads from upper right to lower left (in reference to the body as a whole), considering the tilt of the heart. This is important in understanding the various ECG lead tracings
  4. 4. Conduction System of the Heart Sinoatrial node AV node Bundle of His Bundle Branches Purkinje fibers 4
  5. 5. 5Pacemakers of the Heart SA Node - Dominant pacemaker with an intrinsic rate of 60 - 100 beats/minute. AV Node - Back-up pacemaker with an intrinsic rate of 40 - 60 beats/minute. Ventricular cells - Back-up pacemaker with an intrinsic rate of 20 - 45 bpm.
  6. 6. Impulse Conduction & the ECG Sinoatrial node AV node Bundle of His Bundle Branches Purkinje fibers 6
  7. 7. 7The normal electrocardiogram
  8. 8. 8Electrophysiology of the heartDifferent waveforms for each of the specialized cells
  9. 9. 9 The ECG Paper Horizontally  One small box - 0.04 s  One large box - 0.20 s Vertically  One large box - 0.5 mV
  10. 10. 10The ECG Paper (cont) 3 3 sec sec  Every 3 seconds (15 large boxes) is marked by a vertical line.  This helps when calculating the heart rate. NOTE: the following strips are not marked but all are 6 seconds long.
  11. 11. The “PQRST” P wave - Atrial depolarization  QRS – Ventricular depolarization T wave – Ventricular repolarization 11
  12. 12. The PR Interval Atrial depolarization + delay in AV junction(AV node/Bundle of His)(delay allows time for the atria to contract before the ventricles contract) 12
  13. 13. 13 The ECG Tracing: Waves P- wave  Marks the beginning of the cardiac cycle and measures the electrical impulse that causes atrial depolarization and mechanical contraction QRS- Complex  Measures the impulse that causes ventricular depolarization  Q-wave- may or may not be evident on the ECG  R-wave- first upward deflection following P wave  S-wave- the first downward deflection following the R- wave T- wave  Marks ventricular repolarization that ends the cardiac cycle
  14. 14. 14Intervals and Segments P-R interval-  Time interval for impulse to go from the SA to the AV node  normal 0.12-0.20 secs QRS Interval  Time interval for impulse to go from AV node to stimulate Purkinjie fibers  Less than 0.12 secs QT Interval  Time interval from beginning of depolarization to the end of repolarization  Should not exceed ½ the length of the R-R ST segment  end of the S to the beginning of the T
  15. 15. 15CARDIAC CYCLES Recorded on graph paper.  Time is measured across (x-axis)  Voltage is measured up and down. (y-axis)  Small squares 1mm high 0.04 secs wide  5 small squares = 1 large square  1 large square is 5mm high and 0.20 sec wide
  16. 16. 16Principles ofElectrocardiograph Electrocardiograph – is the instrument that records the electrical activity of the heart Electrocardiogram (ECG) is the record of that activity
  17. 17. 17 ELECTRODE PLACEMENT LIMB LEADS  Bipolar leads: I II III  Augment leads: Avr Avl Avf CHEST LEAD  6 UNIPOLAR LEADS: V1, V2, V3, V4, V5 & V6
  18. 18. Limb Leads 18
  19. 19. 19Chest Leads
  20. 20. 20 I and AVL V3 & v4 V1 & v2II, III and AVF V5 & v6 Where the positive electrode is positioned, determines what part of the heart is seen!
  21. 21. 21Normal ECG
  22. 22. 22
  23. 23. 23
  24. 24. 24ECG Changes: Infarct Significant Q-wave where none previously existed  Why?  Impulse traveling away from the positive lead  Necrotic tissue is electrically dead No Q-wave in Subendocardial infarcts  Why?  Not full thickness dead tissue  But will see a ST depression  Often a precursor to full thickness MI Criteria  Depth of Q wave should be 25% the height of the R wave  Width of Q wave is 0.04 secs  Diminished height of the R wave
  25. 25. Evolving MI and Hallmarks of AMI Q wave ST Elevation 1 year T wave inversion 25
  26. 26. 26A Normal 12 Lead ECG
  27. 27. 27A Normal 12 Lead ECG
  28. 28. 28Color Coding ECG’s Anterior Yellow indicates V1, V2, V3, V4  Anterior infarct with ST elevation  Left Anterior Descending Artery (LAD)  V1 and V2 may also indicate septal involvement which extends from front to the back of the heart along the septum  Left bundle branch block  Right bundle branch block  2nd Degree Type2  Complete Heart Block
  29. 29. 29Anterior MI
  30. 30. 30Color Coding ECG- Inferior Blue indicates leads II, III, AVF  Inferior Infarct with ST elevations  Right Coronary Artery (RCA)  1st degree Heart Block  2nd degree Type 1, 2  3rd degree Block  N/V common, Brady
  31. 31. 31Inferior MI
  32. 32. 32Color Coding ECG- Lateral Redindicates leads I, AVL, V5, V6  Lateral Infarct with ST elevations  Left Circumflex Artery  Rarely by itself  Usually in combo
  33. 33. 33Lateral MI
  34. 34. 34Color Coding ECG- Posterior Green indicates leads V1, V2  Posterior Infarct with ST Depressions and/ tall R wave  RCA and/or LCX Artery Understand Reciprocal changes  The posterior aspect of the heart is viewed as a mirror image and therefore depressions versus elevations indicate MI  Rarely by itself usually in combo
  35. 35. 35Posterior MI
  36. 36. 36Color Coding ECG- SubEndo No color for SubEndocardial infarcts since they are not transmural Look for diffuse or localized changes and non – Q wave abnormalities  T-wave inversions  ST segment depression
  37. 37. 37SubEndo MI
  38. 38. 38More than one color showsabnormalityA combination of infarcts such as:  Anterolateral yellow and red  Inferoposterior blue and green  Anteroseptal yellow and green
  39. 39. 39Putting it ALL together
  40. 40. 40

×