Antiarrhythmics and CHF

Question 1

Digoxin

Answer 1

20-40% protein bound, t1/2=40 hrs, urinary excretion

MOA: Inhibits NA/K pump, decreases NA gradient and traps Ca in myocardium->positive inotrope, also stimulates vagus nerve (cholinergic) to decrease HR

Use: CHF (inc. contractility), A fib (dec AV node conduction, depresses SA node)

SE: Cholinergic! (N/V, diarrhea, blurred vision), Hyperkalemia->Inc PR, Dec QT, T wave inversions, arrhythmia, AV block
Increased Toxicity with renal failure, hypokalemia, drugs that displace Dig from albumin (verapamil, amiodarone, quinidine)

Question 2

Quinidine, Procainamide, Disopyramide

Answer 2

Class 1a Antiarrhythmic
MOA: Slow conduction of Na channel, Increase AP duration, QT, and Effective refractory period
Use: Atrial/Ventricular arrhytmia, re-entrant SVT and VT

Question 3

Na+ Channel Blockers Class 1

Answer 3

Slow/Block conduction (decrease slope) at 0 phase in depolarized cells. Work for Tachyarrhythmias.
Hyperkalemia causes increased toxicity

Question 4

Lidocaine, Mexiletine

Answer 4

1b antiarrythmic
MOA: Decrease AP duration in ISCHEMIA tissue or depolarized purkinje fibers
Use: Acute Ventricular arrhythmia POST MI!
SE: CNS depression, CV depression

Question 5

Flecanide, Propafenone

Answer 5

1c Antiarrhythmic
MOA: Prolong refractory period in AV node
Use: SVTs, A fib
SE: Proarrhythmic, CI in post MI

Question 6

Beta Blockes

Answer 6

Class II antiarrhythmic (Decrease slope of Phase 4) pacemaker upstroke
MOA: Decrease SA/AV nodal activity by decreasing cAMP and Ca+2 current, Increase PR interval (AV node)
Use: SVT, Slowing HR in A fib and flutter
SE: Impotence, COPD exacerbation, bradycardia, CNS (sedation)

Question 7

Amiodarone, Ibutilide, Dofetilide, Sotalol (AIDS)

Answer 7

Class III K+ channel blocker (Prolonged repolarization)
MOA: Increase AP duration, Increase ERP, INCREASE QT
Use: A fib, A flutter, V tach
SE: Sotalol: Torsades, Ibutilide: Torsades,
Amiodarone: Pulmoary fibrosis, hepatotoxic, hypo/hyperthyroid b/c it is composed of iodine, corneal and skin deposits, CV effects, also has effect on class 1, 2, 3 and 4 antiarrhytmics

Question 8

Verapamil, Diltiazem

Answer 8

Class IV (Ca+2) antiarrhythmic
MOA: Decrease Conduction velocity, Increase ERP, Increase PR
Use: Nodal Arrhythmias, Rate Control in A fib
SE: Constipation, flushing, edema, CHF

Question 9

Adenosine

Answer 9

Increase K+ out of cells, hyperpolarizes, and decreases inward Ca+2 current
Use: SVT!, very short acting (15 seconds)
SE: flushing, hypotension, blocked by caffeine and theophylline

Question 10

Mg+2

Answer 10

Torsades and Dig toxicity!