Anti-arrhythmic Agents Flashcards
Where are “fast” action potentials found?
Atrial and ventricular cardiac myocytes
Where are “slow” action potentials found?
SA and AV Nodes
What does the QT interval reflect?
Ventricular action potential duration
1) What does EAD stand for?
2) What can cause an EAD?
3) What can result from EADs?
4) What type of a heart rate is associated with EAD-induced arrhythmia?
1) Early after depolarization
2) Prolonged action potential –> causes re-activation of Ca++ channels
3) Torsades, runs of spontaneous extrasystolic beats
4) Slow HR
1) What does DAD stand for?
2) What can cause a DAD?
3) What type of a heart rate is associated with DAD-induced arrhythmia?
1) Delayed afterdepolarization
2) Abnormal intracellular Ca++ handling, ischemia, digoxin toxicity
3) Fast HR
What drug classes reduce automaticity by decreasing the slope of phase 4?
Beta and Ca++ Channel Blockers
What drug classes reduce automaticity by increasing the threshold for an AP?
Na+ and Ca++ Channel Blockers
What drug reduces automaticity by increasing the maximum diastolic potential? How?
Adenosine, potentiates K+ leak channel to lower the resting state
What drug class reduces automaticity by increasing action potential duration?
K+ channel blockers
What drug classes lengthen the refractory period?
Ca++, Na+, and K+ channel blockers
What are the major mechanisms for:
1) Class I drugs
2) Class II drugs
3) Class III drugs
4) Class IV drugs
1) Na+ channel block
2) B-adrenergic receptor block
3) K+ channel block
4) Ca++ channel block
What is the speed of kinetics associated with and how does that effect the AP:
1) Class IA drugs
2) Class IB drugs
3) Class IC drugs
1) medium kinetics, prolong AP
2) fast kinetics, shorten AP
3) slow kinetics, minimal effect on AP
Disopyramide
1) Class of drug
2) Use
3) Side effects
1) Class IA –> Na+ channel blocker (also some K+ block)
2) Ventricular arrhythmias and recurrent atrial arrhythmias; **AVOID in HF
3) Negative inotrope
Procainamide
1) Class of drug
2) Use
3) Side effects
1) Class IA –> Na+ channel blocker (also some K+ block)
2) Ventricular arrhythmias and recurrent atrial arrhythmias
3) Lupus-like effect, nausea **NAPA metabolite –> EADs, arrhythmias
Quinidine
1) Class of drug
2) Use
3) Side effects
1) Class IA –> Na+ channel blocker (also some K+ block)
2) Ventricular arrhythmias and recurrent atrial arrhythmias
3) Diarrhea
Lidocaine
1) Class of drug
2) Use
3) Side effects
1) Class IB –> Na+ channel blocker
2) Acute ventricular arrhythmias
3) CNS toxicity
Mexiletine
1) Class of drug
2) Use
3) Side effects
1) Class IB –> Na+ channel blocker
2) Chronic ventricular arrhythmias
3) CNS toxicity
Flecainide
1) Class of drug
2) Use
3) Side effects
1) Class IC –> Na+ channel blocker
2) Recurrent atrial arrhythmias
3) Arrhythmogenic **avoid with structural heart disease or post MI
Propafenone
1) Class of drug
2) Use
3) Side effects
1) Class IC –> Na+ channel blocker
2) Recurrent atrial arrhythmias
3) Arrhythmogenic **avoid with structural heart disease or post MI
Amiodarone
1) Class of drug
2) Use
3) Side effects
1) Class III - K+ channel blockers (pleotropic effects on other channels as well)
2) Atrial and ventricular arrhythmias
3) Bradycardia, **accumulates in tissues causing pulmonary, liver, thyroid, eye, skin toxicity
Dofetilide
1) Class of drug
2) Use
3) Side effects
1) Class III - K+ channel blockers
2) Atrial arrhythmias
3) Marked QT prolongation –> torsades
* *safer in HF
Ibutilide
1) Class of drug
2) Use
3) Side effects
1) Class III - K+ channel blockers
2) Acute conversion of afib/flutter
3) Marked QT prolongation –> torsades
Sotalol
1) Class of drug
2) Use
3) Side effects
1) Class III - K+ channel blockers
2) Atrial and ventricular arrhythmias
3) Bradycardia, marked QT prolongation –> torsades
Dronedarone
1) Class of drug
2) Use
3) Side effects
1) Class III - K+ channel blockers
2) Atrial and ventricular arrhythmias
3) **derivative of amiodarone –> less thyroid and pulmonary toxicity
Diltiazem
1) Class of drug
2) Use
3) Side effects
1) Class IV - Ca++ channel blockers
2) Re-entry SVT involving AV node, slow AV node conduction
3) Bradycardia, hypotension, negative inotrope
Verapamil
1) Class of drug
2) Use
3) Side effects
1) Class IV - Ca++ channel blockers
2) Re-entry SVT involving AV node, slow AV node conduction
3) Bradycardia, hypotension, negative inotrope
Digoxin
1) Mechanism
2) Use
3) Side effects
1) Sensitizes PS efferents and inhibits Ica –> potentiates muscarinic receptors
2) Slows ventricular response for Afib/flutter
3) Arrhythmogenic
Adenosine
1) Mechanism
2) Use
3) Side effects
1) Activates Ik and inhibits Ica –> decreases AV node resting potential and slows conduction through AV node
2) SVT, afib/flutter
3) Brief asystole, AV node block
* * VERY short 1/2 life –> IV push into big vein
