CVS - Arrhythmias and Anti-arrhythmics Flashcards
What are the phases of cardiac action potential?
0: Rapid depolarization, 1: Initial repolarization, 2: Plateau, 3: Repolarization, 4: Resting potential.
What is the mechanism of Class I antiarrhythmic drugs?
They block sodium channels, reducing excitability and conduction velocity.
What is the action of Class II antiarrhythmics?
They reduce heart rate and contractility by blocking beta-adrenergic receptors.
How do Class III antiarrhythmics work?
Potassium channel blockers: They prolong repolarization by inhibiting potassium efflux.
What is the mechanism of Class IV antiarrhythmics?
(Non-DHP Calcium Channel Blockers) They reduce calcium influx at SA & AV node, decreasing heart rate and nodal conduction.
What is the role of Adenosine in antiarrhythmic therapy?
It slows AV nodal conduction, useful in paroxysmal supraventricular tachycardia.
How are Class I antiarrhythmics classified?
Into subclasses IA, IB, and IC, based on their effect on action potential duration.
What are the clinical uses of Class I antiarrhythmics?
They are used in ventricular and supraventricular tachycardias.
What are common adverse effects of Class II antiarrhythmics?
Bradycardia, AV block, and bronchospasm.
Which antiarrhythmic drug has a long elimination half-life and is used in various arrhythmias?
Amiodarone.
What is the main adverse effect of Class III antiarrhythmics?
Symptomatic Bradycardia and Heart Block
What is a significant contraindication of Non-DHP Calcium Channel Blockers?
Patients with preexisting depressed cardiac function
What is the mechanism of action of Lidocaine as an antiarrhythmic?
It blocks sodium channels, used in acute ventricular arrhythmias.
What is a contraindication for using propranolol as antiarrhythmics?
Asthma, diabetes or severe peripheral arterial disease.
Name 2 classes of drugs that are used to treat atrial fibrillation?
Using Beta-Blockers, Calcium Channel Blockers
