Antiarrhythmics Flashcards Preview

Cardio Block > Antiarrhythmics > Flashcards

Flashcards in Antiarrhythmics Deck (18):

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


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


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


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


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


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


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


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**


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**



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

- cardioversion

- radio-frequency ablation


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

0: conduction speed

2/3: refractory period

4: speed of spontaneous depolarization (pacemaker cells)



How would you..


When would sinus tachycardia be pathological?

e.g hyperthyroidism, MI


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)



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

Physiological (sinus)

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


  • 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


  • 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**


Differentiate between cardioversion and defibrillation

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


What does digoxin do?

Prolongs refractory period in pacemaker cells and increases inotropy

(reduces heart rate and increases stroke volume)


What does atropine do?

Atropine is a mAchR 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