Cardiac Dysrhythmias

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  1. Where is the heart located?
    Middle of the thoracic cavity, attached to the thorax via great vessels
  2. Which heart layer is responsible for contraction and pumping?
  3. Atria vs. Ventricles
    • Atria: receive blood from the body
    • Ventricles: pump blood to lungs and body
  4. Where do the Tricuspid and Mitral (Bicuspid) valves lie?
    • Tricuspid: between R atrium and R ventricle
    • Mitral: between L atrium and L ventricle
  5. Where do the Semilunar Pulmonary and Aortic valves lie?
    • Pulmonary: from the R ventricle to the pulmonary artery
    • Aortic: from the L ventricle to the Aorta
  6. What supplies the heart with oxygen?
    Coronary Arteries
  7. Cardiac Output Formula is...
    CO= SV (stroke volume) x HR (heart rate)
  8. Define CO. What's the normal adult CO?
    • CO: amount of blood ejected (pumped) by the ventricles in 1 minute
    • Normal adult CO= 4-8 LPM
  9. Define automaticity
    ability to spontaneously initiate an electrical impulse
  10. Major ions in cardiac function
    Potassium (K), Sodium, (Na), Calcium (Ca)
  11. Describe the Polarized state of a cell.  What does it appears as on an EKG?
    • Resting state with no electrical activity.  The inside of the cell is negative, outside is positive with uneven distribution of ions across the cell membrane.
    • EKG Baseline
  12. Describe the Depolarized cell state.
    Inside of cell is positive, outside of cell is negative.
  13. Absolute Refractory Period
    From the onset of QRS to approximately the peak of T wave.  Cells are depolarized and cannot be stimulated.
  14. Relative Refractory Period
    • "Vulnerable Period" because cells are repolarizing and can be stimulated (if stimulus is strong enough) thus possibly resulting in ventricular chaos.
    • Downslope of T wave.
  15. EKG provides information about...
    conduction disturbances, electrical effects of meds and electrolytes, and ischemic damage and injury.
  16. When depolarization moves toward a positive or toward a negative the waveform deflection appears as...
    • Toward positive electrode= upward
    • Toward negative electrode= inverted (downward)
  17. When electrical activity is not detected on an EKG, what appears?
    A straight line is recorded, called the "baseline" or "isoelectric" line
  18. In the bipolar leads, which is always positive? negative?
    • Positive =  L leg electrode
    • Negative = R arm electrode
  19. Lead axis I is?
    RA (-) ----> LA (+)
  20. Lead axis II is?
    RA (-) -----> LL (+)
  21. Lead axis III is?
    LA (-) ----> LL (+)
  22. EKG paper: Small squares?
    Small square: 1mm x 1mm, 0.04 sec
  23. EKG paper: Large squares?
    Large square: 5mm x 5mm, 0.2 sec
  24. P wave represents...
    atrial depolarization and spread of impulse across the L & R atria
  25. PR Segment
    End of P wave, beginning of QRS complex.  Usually represented by an isoelectric line
  26. PR Interval.  What is the normal range?
    • From the beginning of the P wave to the beginning of QRS Complex.  Reflects the impulse travel time from the SA node through the AV node, HB, R & L bundles, and into the Purkinje fibers.
    • Normal range= 0.12- 0.20
  27. QRS Complex.  Normal range?
    • Represents the depolarization of the ventricles and HR.
    • Normal range= 0.06- 0.12
  28. Q Wave...
    a negative deflection following the P wave. Always appears as a negative waveform.
  29. R Wave...
    First positive deflection following the P Wave or Q wave (if present).  Always appears as a positive waveform.
  30. S Wave...
    Negative waveform that follows the R wave. 
  31. R & S waves represent?
    R & S waves represent the depolarization of the L & R ventricles.
  32. ST segment
    End of the S wave, beginning of the T wave
  33. ST elevation/ depression occurs on EKG if...
    above or below by 1mm of the PR segment
  34. ST depression can indicate? ST elevation?
    • Depression: myocardial ischemia, digoxin, or low K
    • Elevation: myocardial injury, infarction, or pericarditis, or cardiac tamponade.

    3 I's of MI (ischemia, injury, infarction)
  35. T Wave
    represents ventricular repolarization
  36. QT Interval. Normal range?
    • From beginning of Q to the end of the T wave. Represents total ventricular activity.
    • Normal range= 0.44 or >
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Cardiac Dysrhythmias

Cardiac Dysrhythmias Class
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