Antidysrhytmics

Question 0

What are two examples of, and the mechanism of action for Class I antidysrhythmic?

Answer 0

Examples are Procainamide, and lidocaine.

Blocks sodium ion channels and suppresses ectopic foci by raising threshold for depolarization. It also slows conduction velocity.

Question 1

What are the 5 classes of antidysrhythmics?

Answer 1

I sodium channel blockers
II beta adnergic antagonists 
III potassium channel blockers
IV calcium channel blockers
V misc

Question 2

What is an example of, and the mechanism of action for Class II antidysrhythmic?

Answer 2

An example is metoprolol

Beta adnergic antagonists slow heart rate, and decrease conduction velocity through AV node.
The competitively inhibit catecholamine activation of beta receptor sites.

Question 3

What are two examples of, and the mechanism of action for Class III antidysrhythmic?

Answer 3

Examples are amiodarone and bretylol

Potassium channel blockers delay depolarization extending the action potential and lengthening the refractory period.

Question 4

What are two examples of, and the mechanism of action for Class IV antidysrhythmic?

Answer 4

Examples are verapamil, and cardizem.

Calcium channel blockers slow conduction through the AV node, decrease automaticity of etopic foci and the SA node, and decrease velocity of cardiac contraction.

Question 5

What are two examples of Class V antidysrhythmics?

Answer 5

Examples are adenosine, and digoxin

Question 6

Chronotropy

Answer 6

Heart rate

Question 7

Inotropy

Answer 7

Myocardial contractility

Question 8

Dromotropy

Answer 8

Myocardial conduction

Question 9

Phase 4 of cardiac muscle cell action potential

Answer 9

Begins cycle, cardiac cells are at rest,waiting for automaticity or transfer of an impulse from adjacent cardiac cell.
Coincides with diastole of the heart.

Question 10

Phase 0 of cardiac muscle cell action potential

Answer 10

Begins with rapid influx of sodium ions through channels in the cardiac cell.
Potassium slowly begins to exit the cell, and depolarization occurs, altering the electrical charge present in the cell.

Question 11

Phase 1 of cardiac muscle cell action potential

Answer 11

Sodium influx decreases while potassium continues to leave the cell slowly.

Question 12

Phase 2 of cardiac muscle cell action potential

Answer 12

Begins movement of calcium into the cell while potassium continues to leave the cell.

Question 13

Phase 3 of cardiac muscle cell action potential

Answer 13

Calcium movement ceases with continued outflow of potassium.

Myocardial contraction and depolarization happen during phase 2 and 3

Question 14

What are the indications for lidocaine and procainamide? Which one is refractory to the other?

Answer 14

V-tach and v-fib

Procainamide refractory to lidocaine for v-fib and pulseless v-tach

Question 15

What contraindication do procainamide and lidocaine share?

Answer 15

2nd and 3rd degree heart block

Question 16

Contraindications for procainamide

Answer 16

Myasthenia gravis, and 2nd/3rd degree heart block

Question 17

Contraindications for lidocaine

Answer 17

Supra ventricular dysrhythmias, stokes-Adams syndrome, 2nd/ 3rd degree heart block,hypersensivity to amide type local anesthetics and bradycardias

Question 18

Precautions that lidocaine and procainamide share

Answer 18

CHF, and h/r impairment

Question 19

Precautions for procainamide

Answer 19

Hypotension,cardiac enlargement, CHF,AMI, ventricular dysrhythmias due from digitalis, h/r impairment, or bronchial asthma

Question 20

Lidocaine precautions

Answer 20

H/r impairment, CHF,hypoxia,respiratory depression, hypovolemia, myasthenia gravis, shock, elderly

Question 21

Lidocaine description

Answer 21

Lidocaine is an antidysrhythmic that suppresses automaticity and raises stimulation threshold of the ventricles. Also causes sedation, anticonvulsant, and analgesic effects.

Question 22

Procainamide description

Answer 22

Procainamide prolongs ventricular depolarization, slows conduction,and decreases myocardial excitability.

Question 23

What are the 4 stop points of procainamide?

Answer 23

1. Up to 17 mg/kg to effect, then1-4 mg/min
2. Ectopic resolves
3. QRS widens more then50% from original
4. Hypotension ensues

Question 24

Adult dose for procainamide

Answer 24

20-30 mg/min IV drip @6-8 mg/kg

Question 25

Pedi dose for procainamide

Answer 25

15 mg/kg over 30-60 min

Question 26

Lidocaine dose for adult

Answer 26

1-1.5 mg/kg q 3-5 min max of 3 mg/kg

Post conversion drip of 2-4 mg/min (1 g/250 cc)

Question 27

Elderly dosing for lidocaine

Answer 27

1/2 of adult

Question 28

Pedi dose of lidocaine

Answer 28

1mg/kg q 3-5 min max of 3 mg/kg

Post conversion 20-50mcg/kg/min