Anti-arrhythmic Agents

Question 1

Where are “fast” action potentials found?

Answer 1

Atrial and ventricular cardiac myocytes

Question 2

Where are “slow” action potentials found?

Answer 2

SA and AV Nodes

Question 3

What does the QT interval reflect?

Answer 3

Ventricular action potential duration

Question 4

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?

Answer 4

1) Early after depolarization
2) Prolonged action potential –> causes re-activation of Ca++ channels
3) Torsades, runs of spontaneous extrasystolic beats
4) Slow HR

Question 5

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?

Answer 5

1) Delayed afterdepolarization
2) Abnormal intracellular Ca++ handling, ischemia, digoxin toxicity
3) Fast HR

Question 6

What drug classes reduce automaticity by decreasing the slope of phase 4?

Answer 6

Beta and Ca++ Channel Blockers

Question 7

What drug classes reduce automaticity by increasing the threshold for an AP?

Answer 7

Na+ and Ca++ Channel Blockers

Question 8

What drug reduces automaticity by increasing the maximum diastolic potential? How?

Answer 8

Adenosine, potentiates K+ leak channel to lower the resting state

Question 9

What drug class reduces automaticity by increasing action potential duration?

Answer 9

K+ channel blockers

Question 10

What drug classes lengthen the refractory period?

Answer 10

Ca++, Na+, and K+ channel blockers

Question 11

What are the major mechanisms for:

1) Class I drugs
2) Class II drugs
3) Class III drugs
4) Class IV drugs

Answer 11

1) Na+ channel block
2) B-adrenergic receptor block
3) K+ channel block
4) Ca++ channel block

Question 12

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

Answer 12

1) medium kinetics, prolong AP
2) fast kinetics, shorten AP
3) slow kinetics, minimal effect on AP

Question 13

Disopyramide

1) Class of drug
2) Use
3) Side effects

Answer 13

1) Class IA –> Na+ channel blocker (also some K+ block)
2) Ventricular arrhythmias and recurrent atrial arrhythmias; **AVOID in HF
3) Negative inotrope

Question 14

Procainamide

1) Class of drug
2) Use
3) Side effects

Answer 14

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

Question 15

Quinidine

1) Class of drug
2) Use
3) Side effects

Answer 15

1) Class IA –> Na+ channel blocker (also some K+ block)
2) Ventricular arrhythmias and recurrent atrial arrhythmias
3) Diarrhea

Question 16

Lidocaine

1) Class of drug
2) Use
3) Side effects

Answer 16

1) Class IB –> Na+ channel blocker
2) Acute ventricular arrhythmias
3) CNS toxicity

Question 17

Mexiletine

1) Class of drug
2) Use
3) Side effects

Answer 17

1) Class IB –> Na+ channel blocker
2) Chronic ventricular arrhythmias
3) CNS toxicity

Question 18

Flecainide

1) Class of drug
2) Use
3) Side effects

Answer 18

1) Class IC –> Na+ channel blocker
2) Recurrent atrial arrhythmias
3) Arrhythmogenic **avoid with structural heart disease or post MI

Question 19

Propafenone

1) Class of drug
2) Use
3) Side effects

Answer 19

1) Class IC –> Na+ channel blocker
2) Recurrent atrial arrhythmias
3) Arrhythmogenic **avoid with structural heart disease or post MI

Question 20

Amiodarone

1) Class of drug
2) Use
3) Side effects

Answer 20

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

Question 21

Dofetilide

1) Class of drug
2) Use
3) Side effects

Answer 21

1) Class III - K+ channel blockers
2) Atrial arrhythmias
3) Marked QT prolongation –> torsades
* *safer in HF

Question 22

Ibutilide

1) Class of drug
2) Use
3) Side effects

Answer 22

1) Class III - K+ channel blockers
2) Acute conversion of afib/flutter
3) Marked QT prolongation –> torsades

Question 23

Sotalol

1) Class of drug
2) Use
3) Side effects

Answer 23

1) Class III - K+ channel blockers
2) Atrial and ventricular arrhythmias
3) Bradycardia, marked QT prolongation –> torsades

Question 24

Dronedarone

1) Class of drug
2) Use
3) Side effects

Answer 24

1) Class III - K+ channel blockers
2) Atrial and ventricular arrhythmias
3) **derivative of amiodarone –> less thyroid and pulmonary toxicity

Question 25

Diltiazem

1) Class of drug
2) Use
3) Side effects

Answer 25

1) Class IV - Ca++ channel blockers
2) Re-entry SVT involving AV node, slow AV node conduction
3) Bradycardia, hypotension, negative inotrope

Question 26

Verapamil

1) Class of drug
2) Use
3) Side effects

Answer 26

1) Class IV - Ca++ channel blockers
2) Re-entry SVT involving AV node, slow AV node conduction
3) Bradycardia, hypotension, negative inotrope

Question 27

Digoxin

1) Mechanism
2) Use
3) Side effects

Answer 27

1) Sensitizes PS efferents and inhibits Ica –> potentiates muscarinic receptors
2) Slows ventricular response for Afib/flutter
3) Arrhythmogenic

Question 28

Adenosine

1) Mechanism
2) Use
3) Side effects

Answer 28

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