Antiarrhythmic Drugs Flashcards
(47 cards)
What are the phases of cardiac cycle (0,2,3,4)
Phase 0 - depolarization. Na+ entering the cell
Phase 2 - More potassium leaving the cell than Calcium coming in, leading to plateau
Phase 3 - Much more potassium leaving, repolarization
Phase 4 - Ready for depolarization in non-pacemaker cells, pacemaker cells depolarizing
How do you treat bradyarrthymias?
Atropine + Beta agonist
What are afterdepolarizations? What can they cause?
These occur when abnormal calcium influx into cardiac cells during or immediately after Phase 3 of ventricular action potential. May lead to extra systoles and tachycardia.
What is the mechanism of the Class IA antiarrhythmics?
Sodium channel blockers, these decrease automaticity and prolong refractory period
Name the 3 Class IA drugs?
Procainamide, Disopyramide, Quinidine
What is a negative side effect of Procainamide?
Causes Lupus erthyremotosis, reversible
What is a side effect of quinidine?
cinchonism - tinnitus
What is the most powerful Class I A drug?
Disopyramide, decreases contractility the most so most likely to cause HF.
What are the side effects of the Class I A drugs?
Ventricular tachycardia, syncope, AV block, decreased contractility leading to HF, Decreased blood pressure due to vasodilation of vascular smooth muscle (lack of sodium)
What is the mechanism of the Class IB antiarrythmics?
These shorten the duration of the action potential, shortening the refractory period. Still sodium channel blockers.
Name the Class IB drugs?
Lidocaine, Tocainide, Mexiletine, Phenytoin
What is significant about Lidocaine?
number 1 drug used to treat arrthymias. Acts as a local anesthetic. Effects takes about one hour.
What are the longer acting Class IB drugs?
Tocainide and Mexiletine (also used to treat pain from diabetic neuropathy). These last about half a day.
What is Phenytoin used to treat?
Digitalis-induced arrthymias, anticonvulsant
What are side effects of Class I B?
Tremors, convulsions, slowed AV nodal conduction velocity which can cause heart block
What are the Class 1C Antiarrhythmics?
These are sodium channel blockers with no effect on action potential.
Name the Class IC drugs?
Flecainide, Propafenone. Side effects: proarrhthmogenic, hyperkalemia increases cardiotoxicity.
What is the mechanism of the Class II antiarrhythmics?
These are Beta Blockers, Slow Phase 4 depolarization. High doses block sodium channels.
Name the 4 Class II drugs used?
Propranolol, Acebutolol, Esmolol, Sotalol
What is the most important effect of Class II Antiarrythmics?
Only class of drugs used to reduce/prevent sudden death from myocardial infarction.
What are Class II antiarryhthmics used for?
Sympathetic-induced tachycardia, paroxysmal supraventricular tachycardia, a-flutter and a-fib, prophylaxis post-MI to prevent sudden death
What are the B1 selective Class II antiarrhythmics?
Esmolol and Acebutolol. Esmolol used in OR for anesthesia induced arrhythmias.
What is Sotalol?
Class II Beta Blocker. Racemic mixture, L-isomer is Beta Blocker and D-isomer is Potassium Channel Blocker.
What are the side effects of Class II drugs?
Decreased HR and conduction, sedation, asthma for non-selective, HF, sexual dysfunction, and decrease in CO.
