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15 Cards in this Set
- Front
- Back
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Class IA Antiarrythmic
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Class 1: Block Sodium Channels
Class 1A: Preferentially Blocks open or activated Sodium channels, lengthens duration of action potential (↑ ERP) Blocks K+ channels, prolonges depolarization ↑ ratio: ERP/ADP prevents reentry Rx: Quinidine, Procainamide, Dispoyramide Quinidine is Prototype PhK: oral, mostly hepatic elimination Use: Broad Spectrum Antiarrhythmic Toxicities: Any Rx which ↑ ERB promotes torsade (except Amiodirone & they don't understand why) Torsade DOC: Mg++ Paradoxical tachycardia |
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Quinidine Syncope
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Quinidine + Digitaslis =
over-long QT interval → syncope & death |
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Quinidine
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Prototype Class 1A Antiarrhythmic
Class 1: Block Sodium Channels Class 1A: Preferentially Blocks open or activated Sodium channels, lengthens duration of action potential (↑ ERP) Blocks K+ channels, prolonges depolarization ↑ ratio: ERP/ADP prevents reentry Rx: Quinidine, Procainamide, Dispoyramide Quinidine is Prototype PhK: oral, mostly hepatic elimination Use: Broad Spectrum Antiarrhythmic Toxicities: Any Rx which ↑ ERB promotes torsade (except Amiodirone & they don't understand why) Torsade DOC: Mg++ Paradoxical tachycardia (anti-muscarinic) Hypotention (Alpha blocker) |
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Class IB Antiarrthythmics
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Class 1: block sodium channels
Class 1B: block inactivated sodium channnels: shortens the duration of the action potential (&↓ ERP by blocking slow Na+ "window" currents) Rxs: Lidocaine, Mexiletine, Tocainide, Phenytoin Lidocaine is the prototype PhK: IV short λ, not effective except as infusion, 1° liver metzm Uses: Ventricular only Toxicities: convlusion |
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Lidocaine
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Class 1: block sodium channels
Class 1B: block inactivated sodium channnels: shortens the duration of the action potential (&↓ ERP by blocking slow Na+ "window" currents) Rxs: Lidocaine, Mexiletine, Tocainide, Phenytoin Lidocaine is the prototype PhK: IV short λ, not effective except as infusion, 1° liver metzm Uses: Ventricular only Toxicities: convlusion |
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Class IC Antiarrhythmics
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Class 1: Block Sodium Channels
Class 1C: block all sodium channels, activated and inactivated, no net effect on duration of action potential or ERP Flecainide QRS widening PhK: oral - mostly renal used for life threatening ventricular arrrthmias, prophylaxis/converstion to sinus of paroxysmal atrial fib/flutter not 2° to structural dz Contraindicated post-MI most common side effect: blurred vision paradoxical pro-arrhythmic effects in some pts |
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Flecainide
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Class IC Antiarrythmics
Class 1: Block Sodium Channels Class 1C: block all sodium channels, activated and inactivated, no net effect on duration of action potential or ERP Flecainide QRS widening PhK: oral - mostly renal used for life threatening ventricular arrrthmias, prophylaxis/converstion to sinus of paroxysmal atrial fib/flutter not 2° to structural dz Contraindicated post-MI most common side effect: blurred vision paradoxical pro-arrhythmic effects in some pts |
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Class II Antiarryhthmics
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Beta Blockers
propranolol beta --> Gs --> cAMP --> phosphorylated L-Ca2+ --> increased Ca2+ --> inotropy cAMP--> increased sodium funny current --> increased chronotropy increase pacemaker current, increases conduction velocity blockers increase Action Potential Duration and ERP |
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Class III antiarrythmics
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K+ channel inhibitors, ↑ ERP
sotalol, amiodarone |
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Amiodarone
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1°ily Class III: used for life theratening ventricular arrhythmias, atrial or ventricular arrhythmias
oral/IV; hetapic metzm; λ ≈ mos, takes a month to be effective Class IA: Binds inactivated Na Channels Class IV: some Ca2+ channel blockade effect Class III: Potassium Channel Blockers, Prolong repolarization Slows sinus rate, prolongs QT, inhibits abnormal automaticity notable side effects: NB: does not cause torsades de points --alpha blockade causes peripheral vasodilation --pulmonary fibrosis --thyroid disfunx (iodide) --blue-grey skin, brown-yellow cornea (iodide + CHO) |
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Sotalol (Betapace)
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L-Sotalol: nonselective beta blocker (Class II)
D-isomer: K+ blocker prolongs action potential duration (Class III) Used in ventricular and supraventricular arrhythmias [oral-renal] may cause torsade de points |
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Verpamil
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Class IV Anti-arrhythmic:: Blocks Slow Cardiac Calcium Channels: ↓ HR ↓ contractility
IV/oral-First pass-but largely renally excreted DO2C for reentrant supraventricular tachycardia (Adenosine is DOC) Ventricular Tachycardia + verpamil → Vfib & Death |
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Adenosine
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DOC: very effective/only effective on reentrant supraventricular tachycardias
(PSVT, WPW) slows conduction in the AV node via ↑ K+ conductance, inhibition of cAMP-induced Ca2+ influx IV, seconds long λ |
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Magnesium
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unknown mechanism
useful in both hypomagnesic & normomagnesic states Digitalis Arrhythmias Torsade de points seizures, incl eclampsic seizures |
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K+ as an anti-arrhthmic agent
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both hyper- & hypo-kalemic are arrhythmogenic
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