Pharm: Antiarrhythmics

Question 1

Tx for second degree AV block

Answer 1

Atropine, Dobutamine, Isoproterenol, pacemaker

Question 2

Mechanism of Delayed Afterdepolarization (DAD).

Answer 2

Increased intracellular calcium leads to activation of the Na/Ca pump. The pump brings 3 Na in for each Ca pumped out so the membrane potential increases and can lead to another depolarization

Question 3

Pharmocologic strategy to treat Re-entry tachycardia.

Answer 3

Prolong refractory period, impair conduction thru the unidirectional block

Question 4

Quinidine

Answer 4

MOA: class 1 AA, blocks fast sodium channels

Ind: tachyarrhythmias (a fib., flutter)

AE: Diarrhea
TdP from prolonged QT (has vagolytic effects which prevents K channels from opening and prolong refractory periods), drug interactions b/c inhibits 3A4

Question 5

Procainamide

Answer 5

MOA: class 1A AA, blocks fast sodium channels

Ind: tachyarrhythmias (a fib., flutter)

AE: Lupus Like Syndrome
not as potent vagolytic effect, so less TdP risk

Question 6

Lidocaine

Answer 6

MOA: class 1B AA, blocks fast sodium channels

Ind: short term ventricular arrhythmia, re-entry

AE: seizures, confusion, dizziness

Question 7

Flecainide

Answer 7

MOA: class 1C AA, blocks fast sodium channels

Ind: a. fib, SVT (used only in patients with no other heart problems)

AE: pro-arrhythmia

Question 8

Beta Blockers

Answer 8

MOA: class 2 AA, blocks beta adrenergic receptors

Ind: tachyarrhytmia, a fib, flutter

AE: can cause AV block, sinus bradycardia

Question 9

Which beta blocker has class 3 AA action?

Answer 9

Sotalol

Question 10

Amiodarone

Answer 10

MOA: class 3 AA, blocks potassium channels

Ind: any tachyarrhythmia, 1st line for emergent v. tach

AE: Pulmonary Fibrosis
prolongs action potential leading to longer QT and TdP

Question 11

Verapamil

Answer 11

MOA: class 4 AA, blocks L-type Ca channels

Ind: AVNRT, V. tach

AE: AV block and sinus bradycardia

Question 12

Diltiazem

Answer 12

MOA: class 4 AA, blocks L-type Ca channels

Ind: AVNRT, V. tach

AE: AV block and sinus bradycardia

Question 13

Adenosine

Answer 13

MOA: A1 receptor agonist, binding decreases cAMP levels, decreasing sodium and calcium influx

Ind: SVT, WPW syndrome

AE: asystole (but short half-life so the asystole is short)

Question 14

Digoxin

Answer 14

MOA: not fully understood, inhibits Na/K pump and increases vagal tone to the AV node

Ind: CHF with a. fib

AE: toxicity due to narrow therapeutic index

Question 15

Tx for digoxin induced toxicity (V tachycardia).

Answer 15

digoxin-immune Fab (digoxin antibody fragments) lidocaine

phenytoin

Question 16

Magnesium (MgSO4)

Answer 16

MOA: unknown (seems to effect all ion channels)

Ind: prevent recurrent TdP, digoxin toxicity