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Flashcards in Antiarrhythmics Deck (18):
1

What are th four classes of antiarrhythmics?

Class 1: sodium channel blockers

Class2 : Beta blockers

Class 3: K channel blockers

Class 4 : Ca channel blockers

2

What ions are involved in which stage of the action potential of a working cardiomyocyte?

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3

What would an ECG overlayed on a working cardiomyocyte AP look like?

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4

What do Na channel blockers (class I) do to the AP of a working cardiomyocyte?

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5

What do K blockers (classIII) do to the AP of a working cardiomyocyte?

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6

What ions are involved in the AP of a pacemaker cell?

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7

What do beta blockers (class II) and calcium channel blockers (class 4) to the AP of a pacemaker cardiomyocyte?

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8

What are the pharmocological and invasive treatment options for bradycardia? What kind of bradycardia is each most likely to work for?

Need to speed up the SA node:

  • pacemaker to the ventricle
  • inhibit PNS (atropine)
  • stimulate SNS (epi or dopamine)

**pacing is required for conduction blocks**

**pharmacological works for sinus bradycardia**

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9

What are the different kinds of tachycardia? Which ones are pathologic and need to be treated?

Sinus (can be either)

Atrial  (ATach, A flutter, Afib, multifocal atrial tach...ALWAYS pathological)

AV node (always pathological)

Ventricular (always pathologic)

**the last three are usually generated by re-entry circuits, so are treated accordingly**

 

10

What are 2 non-pharmacological treatments for tachycardia (of any kind)

- cardioversion

- radio-frequency ablation

11

What do phases 0,1,2,3,4 determine?

0: conduction speed

2/3: refractory period

4: speed of spontaneous depolarization (pacemaker cells)

 

12

How would you..

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13

When would sinus tachycardia be pathological?

e.g hyperthyroidism, MI

14

Generally, class II and IV manipulate ______ and class I and III manipulate______

Class II and IV (b-blockers and Ca channel inhibitors) manipulate pacemaker action potential (lengthen phase 4 and 0 respectively)

Class I and III (Na and K channel blockers) manipulate working cardiomyocyte action potential (conduction speed and refractory period respectively)

 

15

How do you treat tachycardias? Hint: divide them into physiological and re-entry

Physiological (sinus)

  • B-blockers (1st choice) and calcium channel blockers

Atrial:

  • beware of clots
  • try to break the re-entry circuit (Class 1 and class 3)
  • if you can't break the circuit, can try electrical conversion
  • if you still can't break the circuit you need to depress the AV node so the heart rate slows down (B-blockers, calcium channel blockers, digoxin)

AV node

  • vagal maneouvres to "reset" AV node (valsalva, carotid massage)
  • pharmcological slowing of AV node (B-blockers, Ca channel blockers, adenosine

Ventricular

  • break re-entry circuit in working myocytes (Class I and class III)

***But really you can split them into SVT and VT, because all SVT involves supressing AV node**

16

Differentiate between cardioversion and defibrillation

Both deliver a shock, but cardioversion is timed to NOT coincide with the T wave (prevent VFib)

17

What does digoxin do?

Prolongs refractory period in pacemaker cells and increases inotropy

(reduces heart rate and increases stroke volume)

18

What does atropine do?

Atropine is a mAchR antagonist...it is anticholinergic. It will increase heart rate

Red as a beet

Hot as a hare

Dry as a bone

Mad as a hatter

Blind as a bat