Antiarrhythmics

Question 1

Sotalol

Answer 1

Class III (also a β-blocker)
MOA: K+ channel blocker, decreases SA and AV nodal conduction
Effect: increase AP and ERP
Use: life-threatening ventricular tachycardia or A-fib
SE: torsade (and class II cautions - asthmatics, peripheral vascular dz, DM)

Question 2

Procainamide

Answer 2

Class 1A
MOA: metabolized by N-acetyltransferase to NAPA an active metabolite which blocks active Na+ channels
Effect: prolong QT
SE: SLE-like syndrome d/t anti-histone Ab, torsades

Question 3

Class IV Antiarrhythmic Drugs

Answer 3

MOA: Ca2+ channel blockers cardiospecific non-dihydropyridines
Verapamil / Diltiazim

Question 4

Class II Antiarrhythmic Drugs

Answer 4

MOA: β-blockers

Propranolol / Metoprolol / Esmolol

Question 5

Esmolol / Metoprolol / Propranolol

Answer 5

Class II
MOA: β-adrenergic blocker, decreases phase 4 of the nodal AP
Effect: slows SA and AV node firing
Use: prevent ventricular arrhythmias s/p MI, used in SVT to protect ventricles from fast atrial rate

Question 6

Lidocaine / Mexiletine

Answer 6

Class 1B
MOA: blocks inactive Na+ channels
Effect: decreased Na+/K+ ATPase activity
Use: s/p MI, in Digoxin toxicity, open heart surgery

Question 7

Dofetilide

Answer 7

Class III
MOA: K+ channel blocker
Effect: prolongs QT and converts A-fib or flutter to NSR
SE: torsades (only administered in hospital setting)

Question 8

Adenosine

Answer 8

Class V
MOA: AV nodal blockade via A1 (Gi) on SA and AV node, A2A (Gs) vasodilation including coronaries
PK: t1/2 about 30 seconds
DOC: paroxysmal SVT (PSVTs)
Use: s/p MI increases survival

Question 9

Digoxin (antiarrhythmic)

Answer 9

MOA: inhibition of cardiac Na+/K+ ATPase in
Effect: increased intracellular Na+ depolarizes cell
Use: CHF, SVTs, A-fib
SE: N/V/D, visual disturbances (halos or color changes)
CI: WPW
Drug interactions: displaced by Amiodarone, Quinidine, Verapamil, Propafenone (increasing toxicity)

Question 10

Class III Antiarrhythmic Drugs

Answer 10

MOA: K+ channel blockers
Effect: inhibit repolarization
(Amiodarone / Sotalol / Dofetilide)

Question 11

Quinidine / Procainamide / Disopyramide

Answer 11

Class IA

Question 12

Magnesium

Answer 12

Class V
Ca2+ antagonist
Use: tx Torsades de pointes, Digoxin-induced arrhythmia, prophylaxis of arrhythmia in acute MI

Question 13

Heparin (IV)

Answer 13

Use: unstable pt who require immediate cardioversion

Question 14

Quinidine

Answer 14

Concomitant Class III activity (block K+ channels)

Question 15

Class I Antiarrhythmics

Answer 15

MOA: Fast Na+ channel blockers
1A: Quinidine, Procainamide, Disopyramide
1B: Lidocaine, Mexiletine
1C: Fecainide, Propafenone

Question 16

Warfarin (oral)

Answer 16

In stable pt cardioversion should be delayed only for 3-4 wks until adequate anticoagulation has been achieved
*continue oral anticoags at least 4 wks s/p procedure

Question 17

Disopyramide

Answer 17

MOA: blocks active Na+ channels
Effect: stronger anticholinergic

Question 18

Amiodarone

Answer 18

Class III (w/ Class 1A, II and IV activity too)
MOA: block delayed rectifier K+ current
Effect: delay repolarzation, prolongation of AP and ERP, increase QRS, prolong QT
Metabolism: high tissue protein binding
SE: pulmonary fibrosis, hepatotoxicity, blue-gray discoloration of skin, thyroid dysfunction, QT prolongation

Question 19

Flecainide / Propafenone

Answer 19

Class 1C
MOA: inhibitors of fast Na+ channels
Use: life-threatening V-tach, fibrillation, refractory SVTs (second-line for all uses)
SE: can increase sudden cardiac death by decreasing LV function

Question 20

Mexiletine PK

Answer 20

Available orally for Class 1B antiarrhythmic properties

S

Question 21

Lidocaine MOA:

Answer 21

Blocks inactive Na+ channels, used as anti-arrhythmic or as local anesthetic
*least cardiotoxic of all conventional antiarrhythmics

Question 22

Verapamil / Diltiazem

Answer 22

Class IV
MOA: non-dihydropyridine Ca2+ channel blockers (cardioselective)
Effect: decrease phase 0 and phase 4 in SA and AV node (slow AV nodal conduction to protect ventricles from fast atrial rhythm)
Use: SVTs
Verapamil SE: constipation, gingival hyperplasia, displaces Digoxin (increasing concentration and toxicity)

Question 23

Esmolol

Answer 23

β-1 selective, available IV

Effect: decrease phase 4 b/c slowing node by decreasing SANS input

Question 24

Atropine

Answer 24

Use: bradyarrhythmias to decrease vagal tone