Anti-Arrythmia Drugs: Flashcards
What is an Arrhythmia?
-Abnormal heart rhythm, different than sinus (72 bpm)
Bradycardia= less than 60 bpm
Tachycardia= more than 100 bpm
What is the usual treatment for a HR less than 30 bpm?
A pacemaker.
What is the usual treatment for an emergency HR greater than 150 bpm?
DC Cardioversion
**Surgical procedure to correct arrhythmia,
Lidocaine
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.
Quinidine
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)
Which class of drugs are generation arrhythmias treated with?
(Generation arrhythmia= pacemaker cells- too fast or too slow)
- Treated with Class 2 or Class 4 drugs mainly
- ->Beta blockers and Calcium Channel Blockers
Which class of drugs are re-entry arrhythmias treated with?
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
Ways to treat SVT, Atrial Flutter and Atrial Fibrillation?
Bring increased heart rate back down to sinus rhythm.
–>Mechanical manipulation such as Direct Current Cardioversion, Ablation and inserting a pacemaker!
Metoprolol:
–>Beta Blocker
Decreases SA node/ pacemaker potential
*BLOCKS NE binding on Beta1 receptors, which decreases conduction velocity.
Sotalol:
Beta Blocker AND K+ Channel Blocker
Amiodarone:
Class 3 K+ Channel Blocker:
- Prolongs PQ Interval
- ->Blocks K+ exit from cardiac myocytes, ensuring a prolonged hyperpolarization (prolongs AP)
- Decreases conduction velocity.
Verapamil:
CCB
-Slows conduction velocity in the AV node
Diltiazem:
CCB
-Slows conduction velocity in the AV node
What are the 3 main treatments for Torsades des pointes (Tdp)?
-Mg2+, Isoprenaline and bicarbonate (HCO3-)
If arrhythmia persists after ablation, which class of drugs is to be used?
Class 3:
K+ channel blockers
–>Sololol or Amiodarone
Is Digoxin helpful in treating SVT, Atrial Fibrillation, Atrial Flutter or PAT?
Yes, but it is problematic due to its long term toxicity.
Which class of drugs should be used to prevent arrhythmia in a patient whose experienced myocardial infarction (necrosis of the heart tissue) ?
Beta Blockers!
-Metoprolol
Which class of drugs should be used to supress arrhythmia due to a unidirectional block?
Class 1 Anti-Arrhythmias (LIDOCAINE)
- ->Converts a unidirectional block into a bidirectional block
- Further depresses conduction through the damaged area (ischemic area)
Lidocaine main uses?
Na+ channel blocker!
–>Ventricular arrhythmias, such as Ventricular Tachycardia (slows down Phase 0)
3 main drugs which can bring down conduction velocity of the heart?
- Beta Blocker (metoprolol)
- CCB (Verapamil)
- -Digoxin
Amiodarone main uses?
-K+ channel blocker
Useful to treat SVT and ventricular arrhythmias, as well as Atrial Fibrillation/ Flutter.
What is the downside to using Class III agents to treat Arrhythmia?
- Precipitate prolonged QT syndrome
- ->Tdp
Which is considered the least pro-arrhythmic drug? (Most commonly used)
- Amiodarone!
* However, adverse effects make it an atomic bomb on the system.
Drugs which induce Tdp?
Methadone (used to treat opioid addiction) Haloperidol (Anti-psychotic) Quinidine/ Procainamide (Na+ channel blocker) All class 3 agents (K+ channel blockers)
