1. Define arrhythmia
    Cardiac rhythm that is not normal sinus rhythm
  2. Tachycardia
    Rate > 100 bpm
  3. Bradycardia
    Rate < 60 bpm
  4. What is the relative refractory period?
    • Late phase of A.P. - cell not fully repolarized
    • If stimulated, A.P. will be abnormal
  5. Why is AV conduction delayed?
    Allows time for atria to empty before ventricles contract
  6. Decremental conduction
    Slower or blocked AV conduction
  7. Wolff-Parkinson-White Syndrome
    • Congenital muscle remnant creates additional AV electrical connection (macroreentry)
    • Premature ventricular contraction
  8. Subsidairy pacemaker cells
    • AV node - 50 bpm intrinsic
    • Pukinje cells - 30 bpm intrinsic

    Overdrive suppressed by SA node
  9. Define Reentry
    Self-perpetuating pattern of depolarization
  10. Conditions of reentry
    • Difference in refractory periods
    • Slow conduction in one pathway
    • Unidirectional block of one pathway
  11. Types of reentry
    • Anatomic reentry (macro/micro) - obstacle is fixed
    • Functional reentry - diffuse abnormalities in tissue
  12. How to treat reentrant arrhythmias?
    Administer large electrical shock to whole heart
  13. Causes of bradycardia and ECG signs
    • Decreased automaticity - all P waves have QRS
    • Failure of conduction - delayed P or no QRS
  14. Bezold-Jarisch reflex
    • Bradycardia with vasodilation
    • Casued by decrease in ventricular volume
  15. First degree AV block
    • Increased PR interval, each P has QRS
    • Usually due to increased vagal tone
  16. Second degree AV block
    Mobitz 1 - gradual PR interval increase before blocked beat (atropine or exercise cures)

    Mobitz 2 - random loss of QRS (degenerative His-Purkinje)
  17. Third degree AV block
    • Complete failure of conduction (no QRS after P)
    • Needs pacemaker to prevent asystole
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