Anti-Arrythmia Drugs:

Question 1

What is an Arrhythmia?

Answer 1

-Abnormal heart rhythm, different than sinus (72 bpm)
Bradycardia= less than 60 bpm
Tachycardia= more than 100 bpm

Question 2

What is the usual treatment for a HR less than 30 bpm?

Answer 2

A pacemaker.

Question 3

What is the usual treatment for an emergency HR greater than 150 bpm?

Answer 3

DC Cardioversion

**Surgical procedure to correct arrhythmia,

Question 4

Lidocaine

Answer 4

Class 1 Anti-Arrhythmia drug.

• Na+ channel blocker- increases Phase 0 threshold and slows action potential firing.
• Keeps the Na+ channel in an inactivated state, meaning both activation/ inactivation gates are closed

–>LITTLE effect on atrial/ AV nodal tissue.

Question 5

Quinidine

Answer 5

Class 1 Anti-Arrhythmia drug.

• Na+ channel blocker- increases Phase 0 threshold and slows action potential firing.
• Keeps the Na+ channel in an inactivated state, meaning both activation/ inactivation gates are closed

–>Adverse Effect: Cinchonism (blurred vision, tinnitus, headache and psychosis)

Question 6

Which class of drugs are generation arrhythmias treated with?

Answer 6

(Generation arrhythmia= pacemaker cells- too fast or too slow)

• Treated with Class 2 or Class 4 drugs mainly
• ->Beta blockers and Calcium Channel Blockers

Question 7

Which class of drugs are re-entry arrhythmias treated with?

Answer 7

Treated with all anti-arrhythmia agents! (Na+ channel blockers, Beta blockers, K+ channel blockers and CCBs)
*Occurs due to unidirectional block.

-To treat SVT, AFib, Ventricular Fib/ Flutter

Question 8

Ways to treat SVT, Atrial Flutter and Atrial Fibrillation?

Answer 8

Bring increased heart rate back down to sinus rhythm.

–>Mechanical manipulation such as Direct Current Cardioversion, Ablation and inserting a pacemaker!

Question 9

Metoprolol:

Answer 9

–>Beta Blocker
Decreases SA node/ pacemaker potential
*BLOCKS NE binding on Beta1 receptors, which decreases conduction velocity.

Question 10

Sotalol:

Answer 10

Beta Blocker AND K+ Channel Blocker

Question 11

Amiodarone:

Answer 11

Class 3 K+ Channel Blocker:

• Prolongs PQ Interval
• ->Blocks K+ exit from cardiac myocytes, ensuring a prolonged hyperpolarization (prolongs AP)
• Decreases conduction velocity.

Question 12

Verapamil:

Answer 12

CCB

-Slows conduction velocity in the AV node

Question 13

Diltiazem:

Answer 13

CCB

-Slows conduction velocity in the AV node

Question 14

What are the 3 main treatments for Torsades des pointes (Tdp)?

Answer 14

-Mg2+, Isoprenaline and bicarbonate (HCO3-)

Question 15

If arrhythmia persists after ablation, which class of drugs is to be used?

Answer 15

Class 3:
K+ channel blockers
–>Sololol or Amiodarone

Question 16

Is Digoxin helpful in treating SVT, Atrial Fibrillation, Atrial Flutter or PAT?

Answer 16

Yes, but it is problematic due to its long term toxicity.

Question 17

Which class of drugs should be used to prevent arrhythmia in a patient whose experienced myocardial infarction (necrosis of the heart tissue) ?

Answer 17

Beta Blockers!

-Metoprolol

Question 18

Which class of drugs should be used to supress arrhythmia due to a unidirectional block?

Answer 18

Class 1 Anti-Arrhythmias (LIDOCAINE)

• ->Converts a unidirectional block into a bidirectional block
• Further depresses conduction through the damaged area (ischemic area)

Question 19

Lidocaine main uses?

Answer 19

Na+ channel blocker!

–>Ventricular arrhythmias, such as Ventricular Tachycardia (slows down Phase 0)

Question 20

3 main drugs which can bring down conduction velocity of the heart?

Answer 20

• Beta Blocker (metoprolol)
• CCB (Verapamil)
• -Digoxin

Question 21

Amiodarone main uses?

Answer 21

-K+ channel blocker

Useful to treat SVT and ventricular arrhythmias, as well as Atrial Fibrillation/ Flutter.

Question 22

What is the downside to using Class III agents to treat Arrhythmia?

Answer 22

• Precipitate prolonged QT syndrome

- ->Tdp

Question 23

Which is considered the least pro-arrhythmic drug? (Most commonly used)

Answer 23

• Amiodarone!

* However, adverse effects make it an atomic bomb on the system.

Question 24

Drugs which induce Tdp?

Answer 24

Methadone (used to treat opioid addiction) 
Haloperidol (Anti-psychotic) 
Quinidine/ Procainamide (Na+ channel blocker) 
All class 3 agents (K+ channel blockers)

Question 25

Which 2 conditions aggravate Tdp?

Answer 25

• ->Hypokalemia

- ->Hypomagnesemia

Question 26

Dronedarone:

Answer 26

K+ Channel Blocker

–>Newer drug- has less adverse effects than amiodarone, however may have less efficacy.

Question 27

What are Beta Blockers most effective in eliminating/ controlling in use of arrhythmias?

Answer 27

• Best at reducing high sympathetic activity
• *RATE CONTROLLERS
• These can overcome supra-ventricular tachycardia

Question 28

What is the drug of choice to overcome SVT?

Answer 28

Calcium channel blockers
-Verapamil and Diltiazem (have a much greater impact on cardiac tissue than vascular tissue, in comparison to DHPS- amlodipine and nifedipine

*Diltiazems use is preferred over verapamil by clinicians.

Question 29

Why are DHPs not used to treat arrhythmia?

Answer 29

• Primarily because they effect vascular tissue MORE than cardiac tissue (vascular effects can cause reflex tachycardia)
• Instead targeted to lower hypertension.

Question 30

Which drugs are used if arrhythmia slips into heart failure?

Answer 30

Digoxin/ nitrates.