Antiarrhythmics

Question 1

Class 1 antiarrhythmics are all sodium channel blockers that:

Answer 1

• decrease slope of phase 1
• increase threshold for firing in abnormal pacemaker cells
• use/state dependence (C>A>B)

Question 2

MOA: Increase AP duration, ERP, QT
CU: A+V, esp re-enterant + ectopic SVT & VT
SE (all): TdP, thrombocytopenia

Answer 2

Class 1a
Quinidine
Procainamide
Disopyramide

Question 3

Quinidine (Class 1a) SE

Answer 3

Cichonism (headache, tinnitus)

Question 4

Procainamide (Class 1a) SE

Answer 4

SLE

Question 5

Disopyramide (Class 1a)

Answer 5

Heart failure

Question 6

MOA: Decrease AP duration, pref affect ischemic or depolarized cells
CU: Acute vent arrhythmias post-MI, digitalis induced arrhythmias
SE: CNS stim/dep, CV depression

Answer 6

Class 1b
Lidocaine,
Mexilitine
(Phenytoin)

Question 7

MOA; Significantly prolong refractory period in AV node; no change in AP duration
CU: SVTs (incl afib)
SE: Proarrhythmic, c/i in structural and ischemic HD

Answer 7

Class 1c
Flecainide
Propafenone

Question 8

• Decrease SA + AV node activity by decreasing cAMP and Ca2+ currents
• Decreases slope of phase 4
• Increases PR interval
  SE: impotence, COPD exacerbation, may mask signs of hypoglycemia. C/I in cocaine users.
  AD: glucagon

Answer 8

Class II - beta blockers

Question 9

Metoprolol (beta blocker) SE

Answer 9

dyslipidemia

Question 10

Propranolol (beta blocker) SE

Answer 10

exacerbate vasospasm in Prinzmetal

Question 11

• Increase AP duration, ERP, QT
• Used when other anti-AR fail
• prolong repolarization (phase 3)

Answer 11

Class III (potassium channel blockers)
Amiodarone
Ibutilide
Dofetilide
Sotalol

Question 12

Sotalol (Class III) SE

Answer 12

TdP, excessive beta blockade

Question 13

Ibutilide (Class III) SE

Answer 13

TdP

Question 14

Amiodarone (Class III) SE

Answer 14

pulmonary fibrosis, hepatoxicity, thyroid (hyper/hypo), corneal deposits, skin deposits,
(Check LFTs, PFTs, TFTs)
Has class I, II, III, IV effects and alters lipid membrane

Question 15

• Decrease conduction velocity;
• increase ERP & PR
  CU: prevention of nodal arrhythmias, rate control in a fib
  SE: constipation, flushing, AV block

Answer 15

Class IV (calcium channel blockers)
Verapamil
Diltiazem

Question 16

Increases K+ efflux –> hyper polarizing the cell and decreasing calcium influx. DOC in diagnosing/abolishing SVTs; short-acting (15s);
SE: flushing, hypotension, chest pain
Effects blocked by theophylline and caffeine

Answer 16

Adenosine

Question 17

Effective in torsade de pointes and digoxin toxicity

Answer 17

Mg2+