Anti-arrhythmics Flashcards
What are class 1 anti-arrhythmics and what phase do they act on?
Sodium channel blockers, acting on phase 0.
What are class 2 anti-arrhythmics and what phase do they act on?
Beta-adrenoreceptor blockers, acting on phase 4.
What are class 3 anti-arrhythmics and what phase do they act on?
Potassium channel blcokers, acting on phase 3.
What are class 4 anti-arrhythmics and what phase do they act on?
Calcium channel blockers, acting on phase 2.
What are the sub-classes of phase 1 and what differentiates them?
Class 1a, increases action potential duration, class Ib, decreases action potential duration, and class 1c, which doesn’t change action potential duration.
Give an example of an oral Ic anti-arrhythmic
Flecanide
Give an example of an intravenous 1b anti-arrhythmic
Lidocaine
What are contraindications in class 1 anti-arrhythmics?
Heart failure, AV block, and previous MI.
What are common ADRs of flecanide?
Dizziness, arrythmia, and visual disturbance.
What are common ADRs of lidocaine?
Nystagmus, hypotension, bradycardia and seizure.
What effect do class III anti-arrythmics have on the heart conduction?
Increase the absolute refractory period and action potential duration.
Give two examples of class III anti-arythmics
Amiodarone and Sotalol (at high dose, acts as class II at low dose).
What is a common ADR of class III anti-arrythmics?
Arrythmia (specifically torsades de pointes, reversible with magnesium)
What is a contraindication for class III anti-arrythmics?
AV block.
Why can amiodarone cause DDIs?
It is a CYP450 inhibitor.
What ADRs can amiodarone specifically cause?
Interstitial lung disease, hypothyroidism and hyperthyroidism.
What effect do class IV anti-arrythmics have on the heart?
Increased refractory period, decreased pacemaker depolarisation, decreased inotropy and chronotropy.
What can class IV anti-arrythmics be used for?
Supraventricular arrythmias, angina and hypertension.
What are some contraindications for class IV anti-arrythmic use?
Heart failure, bradycardia and AV block.
What are some ADRs for class IV anti-arryhtmic use?
Hypotension, bradycardia, heart failure and heart block.
Name 2 class IV anti-arrythmics
Verapamil and Dilteazem
What is adenosine, what can it be used to diagnose, and why is it safe to do so?
It is an AV node blocker, that can be used to diagnose supraventricular tachycardia, and is safe to use as it has a half-life of only a few seconds.
