Exam 7: Anti-arrhythmics

Question 1

Name 2 Class 1A Antiarrhythmics

Answer 1

Quinidine

Procainamide

Question 2

Name one Class 1B Antiarrhythmic

Answer 2

Lidocaine

Question 3

Name one Class 1C Antiarrhythmic

Answer 3

Flecainide

Question 4

Name 3 Class II Antiarrhythmics

Answer 4

Propranolol
Acebutolol
Esmolol

Question 5

Name 2 Class III Antiarrhythmics

Answer 5

Amiodarone

Dofetilide

Question 6

Name 2 Class IV Antiarrhythmics

Answer 6

Verapamil

Diltiazem

Question 7

Name an Antiarrhythmic used in treating SVT

Answer 7

Adenosine

Question 8

What channels do Class I Antiarrhythmics generally affect?

Answer 8

Sodium

Quinidine and a Procainamide metabolite also block K channels

Question 9

Main Mechanism of Class I Antiarrhythmics

Answer 9

Blockage of Na channels, especially during 0 phase (Depolarization) and phase 4 (pacemaker phase), lengthens action potentials, slowing conduction velocity and decreases their rate of spontaneous firing.

Question 10

Main Mechanism of Class IA Antiarrhythmics

Answer 10

Na channel inhibition during 0 phase slows conduction velocity
Intermediate speed of interaction with 0 phase Na channels
K channel inhibition during phase 3 (repolarization) increases the length of refractory periods.

Question 11

Main mechanism of Class 1B Antiarrhythmics

Answer 11

Less of a conduction slowing effect in phase 0 via Na channel inhibition
Rapidly interact with phase 0 Na channels
They inhibit Late Acting Na Channels, which decreases AP duration and refractory period (opposite of Class 1A)

Question 12

Main Mechanism of Class 1C Antiarrhythmics

Answer 12

Marked inhibition of Na channels in phase 0 results in dramatic slowing of conduction velocity
Little to no affect on ERP (effective refractory period)

Question 13

What is an affect that all Class I Antiarrhythmics share to varying degrees?

Answer 13

Increase the threshold of excitability

Question 14

Quinidine Mechanism and Uses

Answer 14

Class IA Antiarrhythmic
Inhibits Na channels (slowing conduction rate) and K channels (Increasing length of ERP)
Recently increased use for V Fib in Brugada Syndrome and A Fib in Short QT syndrome

Question 15

Quinidine Adverse Effects (3)

Answer 15

Can cause arrhythmias (Especially Torsades)
GI problems
Cinchonism (OD)- Kind of like Atropine poisoning (Increased HR, decreased BP,

Question 16

Procainamide

Answer 16

Class IA Antiarrhythmic
Similar to Quinidine, but actions are caused by an acetylated metabolite produced in the liver (NAPA), which happens at different rates in different people.
Can cause Lupus syndrome
Also GI, CNS problems
Less likely to cause Torsades or Atropine-like problems than Quinidine

Question 17

Lidocaine

Answer 17

Class IB Antiarrhythmic
Shortens ERP, phase 3 via inhibition of Late acting Na channels
Mainly treats ventricular arrhythmias caused by ischemia
Can cause CNS depression
Can cause arrhythmias, mainly in the presence of hyperkalemia

Question 18

Flecainide Effects, Uses

Answer 18

Class IC Antiarrhythmic
Mostly slows conduction by markedly inhibiting Phase 0 Na channels
Little to no effect on ERP/AP duration
Used for severe arrhythmias resistant to other drugs

Question 19

Flecainamide Adverse Effects (3)

Answer 19

Negative inotropic (exacerbates CHF)
Very pro-arrhythmic, especially with hyperkalemia
High mortality

Question 20

Class II Antiarrhythmics Mechanism

Answer 20

Beta Blockers
Decrease inward Ca channel current, slowing conduction and depressing automaticity.
Useful in treating arrhythmias caused by too much sympathetic input
Treat supra ventricular arrhythmias

Question 21

Propranolol

Answer 21

Good record of reducing incidence of sudden adrenergically‐driven arrhythmic death after myocardial infarction.
Theoretically could combat arrhythmias with membrane stabilization, but this would require way too high a dose to be safe.

Question 22

Acebutolol

Answer 22

Beta 1 antagonist
Reduces risk of bronchospasm
Partial agonist property may decrease risk of too much suppression of cardiac function

Question 23

Esmolol

Answer 23

Very short acting  blocker used IV in acute arrhythmias occurring during surgery or emergency situations.

Question 24

Beta Blocker Drug Interaction

Answer 24

Dont use them with Ca Channel Blockers, because that risks too much suppression of cardiac function

Question 25

Class III Antiarrhythmics Mechanism

Answer 25

Mainly inhibit K channels during the AP, prolonging repolarization. Prolongs ERP and AP duration without affecting other phases.

Question 26

Amiodarone

Answer 26

Class III Antiarrhythmic Prolongs ERP, AP by inhibiting K channels in Phase 3 Has complex secondary effects. Used in severe tachyarrhythmias

Question 27

Amiodarone Adverse Effects (3)

Answer 27

Lots of bad things that may persist long after the drug is stopped. Interstitial pulm fibrosis thyroid problems Skin discoloration due to iodine build up.

Question 28

Dofetilide

Answer 28

Pure Class III anti arrhythmic Inhibits only K channels, prolonging AP, and ERP Treats supra ventricular arrhythmias, especially A Fib Can cause Torsades

Question 29

Verapamil and Diltiazem

Answer 29

Class IV Antiarrhythmics Calcium channel blockers Work well at AV node, can stop AV node arrhythmias from reaching the ventricles Dont combine with Beta blockers Dont give when a fib is accompanied by WPW, or it may get worse.

Question 30

Adenosine

Answer 30

Decreases conduction velocity and decreases abnormal impulse formation in the AV node Decreases Ca influx and ACh sensitive phase 4 K current Prolongs AV node refractory period Drug of choice for paroxysmal supraventricular tachycardia (PSVT) Short duration of action! Can cause Flushing, SOB, and chest pain.

Question 31

Procainamide Adverse Effects (4)

Answer 31

Lupus CNS Problems GI Problems Arrhythmias (Less likely than with Quinidine)

Question 32

Lidocaine Adverse Effects (2)

Answer 32

CNS Depression | Arrhythmias, especially in the presence of hyperkalemia

Question 33

Class II Antiarrhythmic Uses

Answer 33

Arrhythmias caused my too much sympathetic input | Supra ventricular arrhythmias

Question 34

Verapamil/Diltiazem Contraindications

Answer 34

``` Wolf Parkinson White (will make it worse) Beta blockers (will decrease cardiac function too much) ```