N176 - EKG

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  1. Walls of the heart.
    • endocardium
    • myocardium
    • epicardium
    • pericardium
  2. Right coronary artery supplies blood where?
    • SA node 50%
    • AV node 90%
    • Inferior wall of LV
  3. Left coronary artery (left anterior descending - LAD) supplies blood where?
    • anterior wall of LV
    • interventricular septum
  4. Left coronary artery (left circumflex coronary artery) supplies blood where?
    • lateral wall of the L ventricle
    • posterior wall of the L ventricle
    • posterior fascicle of the L bundle branch
  5. Cardiac cycle
    the interval from the beginning of one heart beat to the beginning of the next one
  6. diastole
    atrial or ventricular relaxation -> filling of the ventricles and coronary artery perfusion
  7. systole
    atrial or ventricular contraction
  8. automaticity
    the ability of the cell to spontaneously generate and discharge an electrical impulse
  9. excitability
    the ability of the cell to respond to an electrical impulse
  10. conductivity
    the ability of the cell to transmit and electrical impulse from one cell to the another
  11. contractility
    the ability of the cell to contract when they are depolarized by an electrical impulse
  12. depolarization
    the electrical process by which the resting potential of a resting, polarized cell is reduced to a less negative value
  13. repolarization
    the electrical process by which a depolarized cell returns to its resting polarized state
  14. SA node
    • dominant pacemaker of the heart.
    • rate=60-100 bpm
  15. intermodal atrial conduction tracts
    pathways by which electrical impulses travel from the SA node to the AV node
  16. AV node
    • located on the floor of the right atrium
    • relays electrical impulses from the atrium to the ventricles
    • rate=40-60 bpm
  17. bundle of His
    • located in the upper part of the interventricular septum
    • conducts impulses from the AV node to the R and L bundle branches
    • with the AV node, forms the AV junction
  18. R and L bundle branches
    conduct electrical impulses to the R and L ventricles
  19. Purkinje fibers
    disperse electrical impulses through the ventricles
  20. CO=
    • SV x HR
    • normal range=4-8 L/min
  21. How does the sum of electrical forces flow through the myocardium?
    right to left, top to bottom
  22. Image Upload
    upright/positive complex: impulse is moving toward the positive lead
  23. Image Upload
    inverted/negative complex: impulse is moving away from the positive lead/toward the negative lead
  24. Image Upload
    isoelectric impulse: the impulse is not going toward one or the other. there might not be an impulse, or its jumping around too much to go in one direction.
  25. Bipolar EKG
    and EKG lead with one positive and one negative pole
  26. Unipolar EKG
    and EKG lead with a single positive electrode and a zero reference point, which is placed in the middle of the chest
  27. EKG Lead 1 View
    • Neg=RA
    • Pos=LA
    • looking at the lateral surface of the ventricle
  28. EKG lead 2 view
    • Neg=RA
    • Pos=LL
    • looking at the inferior aspect of the heart
  29. EKG lead 3 view
    • neg=LA
    • pos=LL
    • looking at the inferior aspect of the heart
  30. EKG 5 lead placement
    • clouds over grass, smoke over fire, chocolate near my heart
    • white=RA
    • green=RL
    • black=LA
    • red=LL
    • brown=middle of chest
  31. Normal P wave (lead II)
    • atrial depolarization, electrical conduction from SA to AV node
    • upright, rounded, smooth
  32. notched, biphasic P wave
    • atrial hypertrophy
    • R sided HF, COPD -> inc. intrapulm pressure ->R vent hypertrophy => R atrial hypertrophy
  33. P wave absent
    atrial fibrillation
  34. sawtooth pattern
    atrial flutter
  35. Inverted P wave (lead II)
    retrograde conduction from the AV node
  36. normal PR interval (lead II)
    • time for the atrial impulse to reach the ventricles
    • 0.12-0.20 seconds
    • 3-5 small boxes on an EKG strip
  37. Normal QRS complex (lead II)
    • ventricular depolarization
    • 0.04-0.12 seconds
    • 1-3 small boxes
  38. normal ST segment (lead II)
    • ventricular repolarization, pause after the QRS complex
    • normal=isoelectric
  39. elevated ST segment (lead II)
    indicates myocardial injury
  40. depressed ST segment (lead II)
    • indicative of myocardial ischemia
    • threatening injury, will become elevated if not treated
  41. normal T wave (lead II)
    • ventricular repolarization
    • normal, smooth, and rounded, but larger than the P wave
  42. inverted T wave
    myocardial ischemia
  43. flattened or inverted T wave
    hypokalemia (HF and diuretics)
  44. tall or peaked T waves
    hyperkalemia (digoxin, K replacements, renal pts)
  45. notched T waves
    pericarditis (inflammation of the myocardium)
  46. normal QT interval (lead II)
    • the time between the onset of depolarization and the end of repolarization of the ventricles
    • total duration of ventricular systole
    • normal range=0.35-0.40 seconds
    • 9-10 small boxes
  47. EKG:
    vertical axis
    1 small square=
    1 large square=
    2 large squares=
    • 1 small square=1mm
    • 1 large square=5mm
    • 2 large squares=1mV
  48. EKG rate calculation:
    count the large boxes (thick lines) between R-R
    spaces between lines:
    • lines: 300, 150, 100, 75, 60, 50
    • spaces between 300/150: 1 small box=30 bpm
    • spaces between 150/100: 1 small box=10 bpm
    • spaces between 100/75: 1 small box=5 bpm
    • spaces between 75/60: 1 small box=3 bpm
    • spaces between 60/50: 1 small box=2 bpm
  49. Analyzing EKG strips (8 step method)
    • 1. note the P wave
    • 2. evaluate the atrial rhythm
    • 2. determine the atrial rate
    • 4. calculate the duration of the PR interval
    • 5. evaluate the ventricular rhythm
    • 6. determine the ventricular rate
    • 7. calculate the duration of the QRS complex
    • 8. calculate the duration of the QT interval
    • 9. ID the rhythm
  50. Tachydysrhythmias
    what is it and what happens
    • HR > 100 bpm
    • shorten diastole and coronary perfusion time
    • ↑HR=↓SV, CO, BP
    • increase myocardial oxygen demand
    • longer duration=greater decrease in SV, CO, BP
  51. Bradydysrhythmias
    what is it and what happens
    what if too brady?
    • HR < 60 bpm
    • prolong diastole and coronary perfusion
    • decrease myocardia oxygen demand
    • if too slow, coronary perfusion pressure, CO and BP may fall
Card Set:
N176 - EKG
2013-08-25 07:02:43

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