Arrhythmia Flashcards
What are the Class III antiarrhythmics?
Amiodarone, Dronedarone, Sotalol, Ibutilide, Dofetilide.
What do all of the Class III antiarrhythmics do?
Prolong the QT interval by blocking the potassium channel.
Explain use dependent vs reverse use dependent.
Use dependent: binds with activated channel, works in tachycardia (i.e. Na channel blockers)
Reverse use dependent: works on resting membrane potentials, more effective at slow heart rates (i.e. K channel blockers)
What are the three Class IA drugs?
Quinidine, Procainamide and Disopyramide.
What does Quinidine do? What is it used for?
Blocks INa, Ik and Ito channels, thus prolonging the AP duration and QRS.
It is very effective for atrial fibrillation, but due to its side effects (pro-arrhythmia), it’s only really used for Brugada’s Syndrome and Short QT Syndrome.
What does Procainamide do? What is it used for?
It is a Na channel blocker (prolongs QRS) and a non-specific K channel blocker (increases AP). It has a suppressant action of the SA and AV node, slowing conduction.
It is used for pre-excited atrial fibrillation and in acute setting in the hospital for atrial and ventricular arrhythmia.
What are the side effects of Procainamide?
Hypotension (from ganglionic block) and oral can result in lupus.
What does Disopyramide do? What is it used for?
Blocks Na channel and induces a vagal block.
It is used in the treatment of vagally mediated atrial fibrillation and some ventricular tachycardia. Also for patients with high vagal tone.
Good choice for a patient with slow baseline heart rate.
What are the Class IB drugs? What is unique about them?
Lidocaine and Mexiletine.
They block the Na channel better in ischemic tissue. They do not work in atrial tissue and they shorten the QT interval.
What does Lidocaine do? What is it used for?
Blocks activated and inactivated Na channels and decreases automaticity.
It is the medication of choice in ischemia-related arrhythmia. Used exclusively for ischemic ventricular tachycardia.
What are the side effects of Lidocaine?
Neurological: tremor, seizures, slurred speech, convulsions.
What does Mexiletine do? What is it used for?
It is an oral form of Lidocaine. It is used to treat ventricular tachycardia and is used in combination with QT-prolonging medications.
Side effects: GI disturbance.
What are the Class IC drugs? What do they do?
Flecainide and Propafenone
They are the most potent Class I Na channel blockers (this leads to negative ionotrope, depressing LV function)
What are the Class IC drugs (Flecainide and Propafenone) used for?
They are used to treat atrial and sometimes ventricular tachycardia in a healthy heart.
Also PVCs, atrial fibrillation and prolongs the atrial refractory period.
What does Sotalol do?
It is a non-selective beta blocker and K channel blocker. It increases action potential duration and prolongs the QT interval.
It is used for atrial and ventricular arrhythmia.
It’s excreted renally, so be careful for patients with renal disease. Do not use in patients with prolonged QT.
