S3.1 Cardiac Arrhythmia Drugs Flashcards
What are arrhythmias?
Heart condition with disturbances in;
Pacemaker impulse formation (SAN) or
Contraction impulse conduction (bundle of HIS)
How can arrhythmias form?
Abnormal impulse generation (ectopic focus or early afterdepolaristion)
Abnormal conduction (conduction block, WPW syndrome)
What drugs affect the fast cardiac action potential?
Drugs blocking Na channels slow conduction in phase 0.
Beta blockers decrease phase 4 depolarisation and automaticity.
Drugs blocking K channels increase AP duration.
Drugs blocking Ca channels affect plateau phase and decrease phase 4 depol.
Describe the features of class 1a anti-arrhythmic drugs
Eg: Quinidine, procainamide
Effect on heart: slows phase 0 conduction
ECG: increased QRS
Uses: quinidine for AF, procainamide for ventricular arrhythmias
ADRs: hypotension, proarrhythmia
Describe the features of class 1b anti-arrhythmic drugs
Eg: lidocaine Effect on heart: decrease phase 0 conduction ECG: increased QRS Uses: ventricular tachycardia ADRs: dizziness
Describe the features of class 1c anti-arrhythmic drugs
Eg: flecainide
Effects on heart: decreased phase 0 conduction
ECG: increased QRS
Uses: supreventricular arrhythmia, WPW syndrome
ADRs: proarrhythmia
Describe the features of class 2 anti-arrhythmic drugs
Eg: propanalol, bisoprolol
Effects on heart: decreased phase 4 depol
ECG: increase PR
Uses: treating sinus
ADRs: bronchospasm, hypotension
Describe the features of class 3 anti-arrhythmic drugs - Amiodarone
Effects on heart: increase action potential duration
ECG: increased PR
Uses: WPW syndrome, ventricular fibrillation
ADRs: pulmonary fibrosis and hepatic injury
Describe the features of class 3 anti-arrhythmic drugs - Sotalol
Effects on heart: Increased APD
ECG: increase QT
Uses: ventricular tachycardia
ADRs: proarrythmia, fatigue
Describe the features of class 4 anti-arrhythmic drugs
Eg: verapamil, diltiazam
Effects on heart: increase PR
Uses: Control ventricles during supraventricular tachycardia
ADRs: asystole
What are the features of Adenosine?
Decreases APD and slows AV conduction.
Uses: convert hypotension
What are the features of Vernakalant?
Blocks atrial specific K+ channels, and slows atrial conduction
Uses: Convert AF to sinus rhythm
What are the features of Ivabradine?
Blocks funny current, slows sinus node
Uses: reduce sinus tachycardia
What are the features of Digoxin?
Slows AV conduction
Uses: reduce ventricular rates in AF
What are the features of Atropine?
Muscarinic antagonist, blocks vagal activity to speed AV conduction
Uses: treat vagal bradycardia
