Antiarrhythmics Flashcards

1
Q

What are th four classes of antiarrhythmics?

A

Class 1: sodium channel blockers

Class2 : Beta blockers

Class 3: K channel blockers

Class 4 : Ca channel blockers

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2
Q

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

A
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3
Q

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

A
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4
Q

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

A
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5
Q

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

A
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6
Q

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

A
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7
Q

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

A
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8
Q

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

A

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
Q

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

A

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**

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10
Q

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

A
  • cardioversion
  • radio-frequency ablation
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11
Q

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

A

0: conduction speed

2/3: refractory period

4: speed of spontaneous depolarization (pacemaker cells)

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12
Q

How would you..

A
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13
Q

When would sinus tachycardia be pathological?

A

e.g hyperthyroidism, MI

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14
Q

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

A

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)

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15
Q

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

A

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**

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16
Q

Differentiate between cardioversion and defibrillation

A

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

17
Q

What does digoxin do?

A

Prolongs refractory period in pacemaker cells and increases inotropy

(reduces heart rate and increases stroke volume)

18
Q

What does atropine do?

A

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