Antiarrhythmics

Question 1

Antiarrhythmic

• Class I = Sodium channel blocker for cardiac myocytes
• Group IA
• Moderate conduction slowing
• Prolongs refractory period
• Blocks both Na and K channels–> longer AP–> slows reentrant circuit–> can slow below rate of SA node

Answer 1

Procainamide

Question 2

Antiarrhythmic

• Class I = Sodium channel blockerfor cardiac myocytes
• Group IB
• Little conduction blocking
• Shortens refractory period
  
  • Binds inactivated sodium channels and keeps them in inactivated state–> increase in depolarized tissue–> decreased automaticity in depolarized cells
  • Preferentially binds in damaged tissue better and longer–> better at blocking ectopic pacemakers in damaged tissue
• Use to treat ventricular tachycardia or fibrilation

Answer 2

Lidocain

Question 3

Antiarrhythmic

• Class I = Sodium channel blocker for cardiac myocytes
• Group IC
• Profound conduction slowing
• Used to treat life threatening arrhythmias, when nothing else is working
  
  • Most likely to cause arrhythmias

Answer 3

Flecanide

Question 4

Antiarrhythmic

• Class III = K channel blocker
• Prolong depolarization–> Prolonged refractory period
• Break reentrant circuit
• Can induce arrhythmias by prolonging action potentials, thyroid problems from iodine(also blue skin discoloration), pulmonary fibrosis

Answer 4

Amiodarone

Question 5

Antiarrhythmic

• Class IV = calcium channel blockers
• Non-vascular specific = nodal cells, cardiac myocytes, vessels
  
  • Also affects cardiac muscle: don’t use with cardiac insufficiency
• Used to decrease ventricular response to atrial fibrilation
• Can cause AV block–> induce arrhythmia–> ventricular escape rhythm from pace maker site in ventricles(usually slower)

Answer 5

Diltiazem and Verapamil

Question 6

Antiarrhythmic and Modulator of Cardiac Contractility

• Decrease AV node conduction–> Decreases ventricular response to atrial fibrillation
• Indirectly decrease calcium efflux by inhibiting Na/K ATP-ase–> increase intracellular Na–> decreased gradient to use to move Ca–> greater contractility
• Cardiac glycoside

Answer 6

Digoxin

Question 7

Antiarrhythmic

• Terminate supraventricular tachycardias involving AV node
• Half-life of about 5 seconds(give IV)–> ID supraventricular arrhythmia involving AV node

Answer 7

Adenosine