Antiarrhythmic Drugs Flashcards

Questions and Answers

What is automaticity?

Ability of cardiac cells to depolarize spontaneously.

What is proarrhythmia?

The provocation of a new arrhythmia or the aggravation of a pre-existing one during therapy with a drug at doses or plasma concentrations below those considered to be toxic.

What are pacemaker cells responsible for?

Cardiac rate (aka chronotropy).

What are cardiac myocytes?

Atrial and ventricular myocytes that respond to depolarization and are responsible for cardiac contraction (aka inotropy). Signup and view all the answers

What does H's and T's of ACLS stand for? (Select all that apply)

Thrombosis Signup and view all the answers

What may cause a proarrhythmia?

Medications. Signup and view all the answers

What are some arrhythmia treatments? (Select all that apply)

Surgery Signup and view all the answers

What is the Vaughan Williams classification used for?

To classify antiarrhythmic drugs based on their dominant cellular electrophysiological effect. Signup and view all the answers

What is the primary action of Class I antiarrhythmic drugs?

Sodium channel blocking Signup and view all the answers

What is the mechanism of action for Class IA drugs?

Moderate depression of phase 0 by blocking fast Na+ channels. Signup and view all the answers

What EKG changes are associated with Class IA drugs?

Widened QRS and prolonged QT interval. Signup and view all the answers

Which of the following are Class IA drugs? (Select all that apply)

Procainamide Signup and view all the answers

What is the primary effect of Class IB drugs on phase 0 depolarization?

Weak effect due to minimal blockage of fast Na+ channels. Signup and view all the answers

What EKG changes are associated with Class IB drugs?

Shortened QT interval Signup and view all the answers

What are Class IC drugs known for? (Select all that apply)

Large effect on phase 0 depolarization Signup and view all the answers

Which of the following are Class IC drugs? (Select all that apply)

Propafenone Signup and view all the answers

What characterizes Class II antiarrhythmic drugs?

Beta blockers (-lol), except sotalol. Signup and view all the answers

What EKG changes are typically seen with Class II drugs?

Increased PR interval. Signup and view all the answers

What are Class III antiarrhythmic drugs primarily used for?

Potassium channel blockers resulting in repolarization delay. Signup and view all the answers

What potential EKG changes may occur with Class III drugs?

Increased QT interval Signup and view all the answers

Which of the following are Class III drugs? (Select all that apply)

Dronedarone Signup and view all the answers

What is the mechanism of action of Amiodarone?

Class III potassium channel blocker with a wide variety of toxicities. Signup and view all the answers

What are the black box warnings associated with Amiodarone?

Appropriate use, pulmonary and hepatic toxicities, and proarrhythmic potential. Signup and view all the answers

Study Notes

Automaticity and Cardiac Function

Automaticity refers to cardiac cells' ability to spontaneously depolarize.
Pacemaker cells are responsible for rhythmically controlling heart rate, while cardiac myocytes enable contraction through depolarization.

Proarrhythmia and H's and T's

Proarrhythmia is the exacerbation of arrhythmias during drug therapy, even at non-toxic doses.
The H's and T's of Advanced Cardiac Life Support (ACLS) include:
- Hypovolemia, Hypoxia, Hydrogen ions (acidosis), Hypothermia
- Toxins, Thrombosis (pulmonary or coronary), Trauma, Tamponade, Tension pneumothorax

Treatments for Arrhythmia

Treatment options include:
- Antiarrhythmic drugs
- Cardioversion and defibrillation
- Implantable cardioverter-defibrillators (ICDs)
- Pacemakers with cardiac resynchronization therapy
- Catheter ablation
- Surgery

Vaughan Williams Classification

A system that categorizes antiarrhythmic drugs based on their primary electrophysiological effects.

Classes of Antiarrhythmic Drugs

Class I: Sodium channel blockers that reduce phase 0 depolarization, divided into three subgroups (A, B, C).

Class IA Antiarrhythmics

Moderate inhibition of phase 0 depolarization with intermediate kinetics.
Associated with widened QRS and prolonged QT interval, increasing the risk of ventricular tachycardia.
Key drugs include Disopyramide, Quinidine, and Procainamide.

Class IB Antiarrhythmics

Display weak effects on phase 0 depolarization with fast kinetics.
Result in narrowed QRS and shortened QT interval.
Include Lidocaine and Mexiletine, with concerns for hepatotoxicity and complications in patients with structural heart disease.

Class IC Antiarrhythmics

Have a significant effect on phase 0 depolarization due to powerful sodium channel blockage and slow kinetics.
They pose risks of proarrhythmias and severe issues in those with structural heart disease.
Notable drugs are Flecainide and Propafenone.

Class II Antiarrhythmics

Consist mainly of beta blockers, excluding sotalol.
Associated EKG changes include increased PR interval.

Class III Antiarrhythmics

Comprised of potassium channel blockers, leading to delayed repolarization.
Can increase QT interval with a risk of Torsades de Pointes.
Important drugs include Dronedarone, Amiodarone, Dofetilide, Ibutilide, and Sotalol.

Amiodarone Characteristics

A unique potassium channel blocker with several potential toxicities, including pulmonary and hepatic concerns.
Known for its slow and variable absorption, long half-life (58 days), and broad spectrum of use.
FDA warnings include proper usage and risk of proarrhythmic effects.

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Description

Explore key concepts related to antiarrhythmic drugs with these flashcards. Each card provides a critical term along with its definition to enhance your understanding of cardiac physiology and pharmacology. Perfect for students and professionals studying cardiology.