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Flashcards in Antiarrhythmics II Deck (27):
1

what are the class III drugs

AiDS
Amiodarone
ibutilide
Dofetilide
Sotalol

2

mechanism of class III drugs

K channel blockers hence increase QT interval

3

special mechanisms of the class III drugs

- Amiodarone has class I (Na channel blocker), II (beta blocker), class III (K channel blocker), and class IV (calcium channel blocker) activity

- dofetilide has no extracardiac effects

- sotalol is a class III drug in addition to having weak beta blocking activity

4

clinical uses of class III drugs

- amiodarone - severe supraventricular and ventricular arrhythmias, acute VT refractory to cardioversion shock, maintain ventricular rate in a-fib pts

- dofetilide - maintenance of normal sinus rhythm, conversion of a-flutter or a-fib to normal sinus rhythm

- sotalol - life threatening ventricular arrhythmias, maintenance of sinus rhythm in pts with a-fib or a-flutter

5

adverse effects of class III drugs

-amiodarone: interstitial pulmonary fibrosis, hypo or hyper thyroidism, corneal deposits, blue grey skin discoloration, photosensitivity

-dofetilide: possible ventricular tachycardia, torsades de pointes

6

contraindication of class III drugs

-amiodarone can alter effects of digoxin, warfarin, theophylline, and quinidine (DWTQ - dancing with Tom Queen)

-bradycardia, hypotension, SA or AV block, severe respiratory failure

7

what are the class IV drugs

diltiazem and verapamil (antihydropyridines)

calcium channel blockers

8

mechanism of class IV drugs

calcium channel blockers and slows conduction in SA and AV nodes

major effect on cardiac and vascular smooth muscle

9

clinical uses of class IV drugs

-supraventricular tachycardia
-reduction of ventricular rate in a-fib and a-flutter

10

adverse effects of class IV drugs

excessive bradycardia, impaired cardiac conduction, depressed contractility

11

contraindications of class IV drugs

preexisting cardiac depressed function

verapamil increases the conc of simvastatin, lovastatin, digoxin, and dofetilide, (SLiDD)

12

what are the miscellaneous drugs used for antiarrhythmias

MAAD
magnesium, adenosine, atropine, digoxin

13

clinical use of digoxin

control of ventricular response rate in atrial fibrillation and flutter with impaired left ventricular function or heart failure

direct AV node blocking effects and activation of vagomimetic properties

14

adverse effects of digoxin

cardiac arrhythmias esp a-tach and AV block

toxic doses can lead to v-tach and v-fib

15

what is adenosine used for

abolishing acute supraventricular tachycardia

16

mechanism of action of adenosine

-enhances K conductance via G protein
-inhibits cAMP mediated ca2+
-hyperpolarization in AV node

17

adverse effects of adenosine

bronchoconstriction can occur in asthmatic patient for up to 30 mins

18

clinical use of magnesium

- torsades de pointes
- digitalis induced arrhythmia
- prophylaxis of arrhythmia in acute MI

19

mechanism of magnesium

functions as a calcium antagonist by preventing the influx of calcium into the cell

20

what is atropine used for

bradyarrhythmias

21

how is a-fib managed

1. slow down ventricular rate
2. prevent thromboembolism
3. correction of rhythm disturbance

22

first line rate control options for a-fib

class II drugs - beta blockers (PEM - propanalol, esmolol, metapronol)
class IV drugs - diltiazem and verapamil

23

when is amiodarone used in a-fib

-patients who are refractory
-or contraindications to beta blockers, calcium channel blockers, digoxin

24

patients with a-fib for longer than 48 hours or an unknown period should be given what and why

warfarin because a-fib can cause clots due to viscous blood (stasis) and can lead to stroke

25

how long is warfarin given to patient with a-fib

for three weeks prior to cardioversion and up to 4 weeks after effective cardioversion and return of normal sinus rhythm

26

what drug is given to patient with a-fib of less than 48 hours and before when?

heparin and prior to cardioversion (DCC - direct current cardioversion)

27

what are the recommended drugs for conversion of a-fib to normal sinus rhythm

F-PAD
flecainamide, propafenone, amiodarone, dofetilide

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