Angina & Antiarrhythmic

Question 1

Types of angina

Answer 1

Stable; Unstable; Prinzmetal’s

Question 2

Drug classes for angina treatment

Answer 2

Organic Nitrates B-Blockers Ca+ Channel Blockers

Question 3

MoA for Organic Nitrates

Answer 3

Decrease coronary vasoconstriction, increase perfusion by relaxing coronary arteries. Also relax veins, decrease preload and cardiac O2

Question 4

MoA for B-Blockers (in Angina Tx)

Answer 4

Decrease O2 demands of myocardium by decreasing rate and force of contraction

Question 5

MoA for CCB

Answer 5

Protect cardiac tissue by inhibiting influx of calcium into cardiac and smooth muscle.

Question 6

Classes of anti-arrhythmics

Answer 6

Class I – Na Channel Blockers; Class II – Beta –Adrenergic Blockers; Class III – K Channel Blockers; Class IV – Ca Channel Blockers; Miscellaneous

Question 7

MoA of Class I - Na Channel Blockers

Answer 7

bind to and block voltage-sensitive Na channels; Decreased rate of entry of Na slows rate of rise of Phase 0 of the action potential

Question 8

MoA of Class II - β-Adrenergic Blockers

Answer 8

Diminish Phase 4 depolarization > depresses automaticity > prolongs AV conduction > decreases heart rate and contractility

Question 9

MoA of Class III - K Channel Blockers

Answer 9

By increasing the ERP, these drugs are very useful in suppressing tachyarrhythmias caused by reentry mechanisms.

Question 10

MoA of Class IV - CCB

Answer 10

Bind to L-type Ca channels located on the vascular smooth muscle, cardiac myocytes, & cardiac nodal tissue

Question 11

MoA of Miscellaneous (Digoxin)

Answer 11

Refractory period shortened in atrial & ventricular cells.

AND

Refractory period prolonged in the AV node

Question 12

Use of Class I - Na Channel Blockers

Answer 12

1. Atrial fibrillation
2. Atrial flutter
3. Supraventricular & ventricular tachyarrhythmias

Question 13

Use of Class II - β-Adrenergic Blockers

Answer 13

1. Atrial Arrhythmias 2. Supraventricular tachycardias

Question 14

Use of Class III - K Channel Blockers

Answer 14

1. Atrial arrhythmias 2. Ventricular tachycardia

Question 15

Use of Class IV - CCBs

Answer 15

1. Atrial arrhythmias (A. fib & A. flutter)
2. Supraventricular tachycardias

Question 16

Use of Miscellaneous (Digoxin)

Answer 16

Control the ventricular response rate in a.fib or flutter

Question 17

Adverse effects for Class I - Na Channel Blockers

Answer 17

1. May cause paradoxical increase in ventricular rate 2. Black Box Warning – Now recommended to reserve these drugs for life threatening arrhythmias

Question 18

Adverse Effects of Class III - K Channel Blockers

Answer 18

1. Precipitation of arrhythmias 2. Similar toxicity to Class IA drugs 3. Caution with other drugs that may cause QT interval prolongation

Question 19

Degree of sodium channel blockade in Class I antiarrhythmics

Answer 19

IC > IA > IB (Not directly related to ERP)

Question 20

Explain how Class I antiarrhythmics effect ERP

Answer 20

Effects on ERP are not directly related to Na channel blockade, but are related to drug actions on K channels (involved in phase 3 repolarization of action potentials)

Question 21

Effect of Class I antiarrhythmics on the slope of phase 0

Answer 21

IC > IA > IB - IC drugs having the greatest and IB drugs having the smallest effect on phase 0 (IA drugs are intermediate in their effect on phase 0)

Question 22

ERP

Answer 22

Effective refractory period - Time required after a conducted impulse is propagated through an area before another impulse can be propagated through the same area