Anti-arrhythmics Flashcards
Drugs that ↓ firing rate of pacemakers:
-CCB: ↑phase 0 threshold\
-NaCB: ↓phase 4 slope
-BetaB:
↓phase 4 slope
↑phase 0 threshold
↑action potential duration
↑maximum diastolic potential
Drugs that ↓ conduction velocity through the AVN:
-CCB: slow impulse propagation
-BetaB
Drugs that ↓ conduction velocity through the atria & ventricles:
-NaCB: slow impulse propagation
Drugs that ↑ refractory period:
-KCB
-CCB
-BetaB
K channel blockers
Increase QT directly without affecting heart rate
↑QT ↔ RR ↑QTc
Beta blockers & Ca channel blockers
Increase QT indirectly by slowing heart rate ↑QT ↑RR ↔ QTc
Arrhythmias: Classification
Arrhythmias: Treatment strategies
Effects of Antiarrhythmic Drugs
Antiarrhythmic drugs have a _____ therapeutic index
narrow
Rate vs Rhythm Control
Beta Blockers and Ca Channel Blockers: Properties
Sodium Channel Blockers: Classes
Class IA sodium channel blockers
MOA:
– Moderate binding to Na channels = ↑QRS interval
– Also block K channels = ↑action potential duration (APD)
– Also block ACh = anti-cholinergic effects
Class IB sodium channel blockers
MOA:
– Weak binding to Na channels = ↔ QRS interval
– ↓action potential duration (APD)
Uses:
– Ventricular arrhythmias only