LAB - 7.1 - Antiarryhtmic Agents

Question 1

The activation gates on the Na+ and K+ channels are closed, and the membrane’s resting potential is maintained.

Answer 1

Resting state

Question 2

A stimulus opens the activation gates on some Na+ channels. Na+ influx through those channels depolarizes the membrane. If the depolarization reaches the threshold, it triggers an action potential.

Answer 2

Depolarization

Question 3

Depolarization opens the activation gates on most Na* channels, while the K* channels’ activation gates remain closed. Na* influx makes the inside of the membrane positive with respect to the outside.

Answer 3

Rising phase of the action potential

Question 4

The inactivation gates on most Na+ channels close, blocking Na* influx. The activation gates on most K+ channels open, permitting K+ efflux which again makes the inside of the cell negative.

Answer 4

Falling phase of the action potential

Question 5

Both gates of the Na+ channels are closed, but the activation gates on some K+ channels are still open. As these gates close on most K+ channels, and the inactivation gates open on Na* channels, the membrane returns to its resting state.

Answer 5

Undershoot

Question 6

is a problem with the rate or rhythm of your heartbeat.

Answer 6

Arrhythmia

Question 7

it means that the heart beats too quickly, too slowly, or with an irregular pattern.

Answer 7

Arrhythmia

Question 8

When the heart beats faster than normal, it is called .

Answer 8

tachycardia

Question 9

When the heart beats too slowly, it is called .

Answer 9

bradycardia

Question 10

The most common type of arrhythmia is ___, which causes an irregular and fast heart beat.

Answer 10

atrial fibrillation

Question 11

Electrical changes associated with atrial depolarization

Answer 11

P wave

Question 12

Electrical changes associated with ventricular depolarization

Answer 12

QRS complex

Question 13

Electrical changes associated with ventricular repolarization

Answer 13

T wave

Question 14

The electrical changes associated with atrial repolarization normally coincide with the ___ complex and are obscured by it.

Answer 14

QRS

Question 15

___ drugs affect the action potential of the cardiac cells, altering their automaticity, conductivity, or both

Answer 15

Antiarrhythmic

Question 16

Can Anti-arrhytmic drugs cause arryhytmia?

Answer 16

YES

Question 17

Classification of Antiarrhythmics (Based on Mechanisms of Action)

Answer 17

Class I – Blocker’s of Fast Na+ Channels

Question 18

Which Class I Sublass features:
Prolong repolarization
Increased duration of action potential

Answer 18

Subclass IA

Question 19

Examples of Subclass IA Medications

Answer 19

Quinidine
Procainamide
Disopyramide

Question 20

Class I Antiarryhtmic Drugs are ___ blockers

Answer 20

Sodium

Question 21

Which Class I Sublass features:
Shortened depolarization
Decreased action potential duration

Answer 21

Subclass IB

Question 22

Examples of Subclass IB Medications

Answer 22

Lidocaine
Mexiletine
Phenytoin

Question 23

This Subclass IB Medication is approved only for use in life-threatening ventricular arrhythmias in adults

Answer 23

Mexiletine

Question 24

Which Class I Sublass features:
No effect of depolarization and on action potential duration

Answer 24

Subclass IC

Question 25

Examples of Subclass IC Medications

Answer 25

Flecainide
Propafenone

Question 26

This Subclass IC Medication was initially developed as a local anesthetic. It slows conduction in all parts of heart

Answer 26

Flecainide (Tambocor)

Question 27

This Subclass IC Medication:
- Also slows conduction
-Weak β – blocker

Answer 27

Propafenone

Question 28

affect predominantly slow-channel tissues (sinoatrial [SA] and atrioventricular [AV] nodes), where they decrease rate of automaticity, slow conduction velocity, and prolong refractoriness

Answer 28

Class II – β–adrenergic blockers

Question 29

Examples of Class II – β–adrenergic blockers

Answer 29

Propranolol
Metoprolol
Atenolol
Pindolol

Question 30

This Class II – β–adrenergic blocker:

Slows SA node and ectopic pacemaking
Can block arrhythmias induced by exercise or apprehension
Other β–adrenergic blockers have similar therapeutic effect:

Answer 30

Propranolol

Question 31

Block potassium channels and slow the outward movement of potassium during phase 3 of the action potential, thereby prolonging it

Answer 31

Class III – K+ channel blockers

Question 32

Developed because some patients are sensitive to Na channel blockers (they died!)

Answer 32

Class III – K+ channel blockers

Question 33

Examples of Class III – K+ channel blockers

Answer 33

Amiodarone
Bretylium
Dofetilide
Sotalol

Question 34

This Class III – K+ channel blocker is the drug of choice for treating ventricular fibrillation or pulse less ventricular tachycardia in cardiac arrest situations

Answer 34

Amiodarone

Question 35

Block the movement of calcium ions across the cell membrane thereby decreasing the excitability and contractility of the myocardium

Slow the rate of AV-conduction in patients with atrial fibrillation

Answer 35

Class IV – Ca+ Channel Blockers

Question 36

Examples of Class IV – Ca+ Channel Blockers

Answer 36

Verapamil
Diltiazem

Question 37

This Class IV – Ca+ Channel Blocker blocks Na+ channels in addition to Ca2+, also slows SA node in tachycardia

Answer 37

Verapamil (Isoptin)

Question 38

There is a risk of severe cardiac effects if Class IV drugs are given IV within ___ hours of IV beta-adrenergic drugs. The combination should be avoided.

Answer 38

48

Question 39

Nursing Implementation for Antiarryhtmic Agents

Answer 39

Titrate the dose to the smallest amount needed to achieve control of the arrhythmia to decrease the risk of severe adverse effects.

Continually monitor cardiac rhythm when initiating or changing dose to detect potentially serious adverse effects and to evaluate drug effectiveness.

Ensure that emergency life support equipment is readily available to treat severe adverse reactions that might occur.

Administer parenteral forms as ordered only if the oral form is not feasible; expect to switch to the oral form as soon as possible to decrease the potential for severe adverse effects.

Consult with the prescriber to reduce the dose in patients with renal or hepatic dysfunction; reduced dose may be needed to ensure therapeutic effects without increased risk of toxic effects.

Establish safety precautions, including side rails, lighting, and noise control, if CNS effects occur to ensure patient safety.

Arrange for periodic monitoring of cardiac rhythm when the patient is receiving long-term therapy to evaluate effects on cardiac status.