Editing Cardioversion (section)

==Medication==
Various [[antiarrhythmic agent]]s can be used to return the heart to normal [[sinus rhythm]].<ref>{{cite web | title = Medications for Arrhythmia | publisher = American Heart Association | url = https://www.heart.org/en/health-topics/arrhythmia/prevention--treatment-of-arrhythmia/medications-for-arrhythmia | access-date = 13 Sep 2020}}</ref> Pharmacological cardioversion is an especially good option in patients with atrial fibrillation of recent onset. Drugs that are effective at maintaining normal rhythm after electric cardioversion can also be used for pharmacological cardioversion. Drugs like [[amiodarone]], [[diltiazem]], [[verapamil]] and [[metoprolol]] are frequently given before electrical cardioversion to decrease the heart rate, stabilize the patient and increase the chance that cardioversion is successful. There are various classes of agents that are most effective for pharmacological cardioversion.

Class I agents are sodium (Na) channel blockers (which slow conduction by blocking the Na+ channel) and are divided into 3 subclasses a, b and c. Class Ia slows phase 0 depolarization in the ventricles and increases the absolute refractory period. [[Procainamide]], [[quinidine]] and [[disopyramide]] are Class Ia agents. Class 1b drugs lengthen phase 3 repolarization. They include [[lidocaine]], [[mexiletine]] and [[phenytoin]]. Class Ic greatly slow phase 0 depolarization in the ventricles (however unlike 1a have no effect on the refractory period).  [[Flecainide]], [[moricizine]] and [[propafenone]] are Class Ic agents.
<ref>{{cite web | title = AED recyclen en inruilen | url = https://www.aedmaster.nl/aed-kennisbank/aed-recyclen/ | access-date = 15 April 2021}}</ref>

Class II agents are beta blockers which inhibit SA and AV node depolarization and slow heart rate. They also decrease cardiac oxygen demand and can prevent cardiac remodeling. Not all beta blockers are the same; some are cardio selective (affecting only beta 1 receptors) while others are non-selective (affecting beta 1 and 2 receptors). Beta blockers that target the beta-1 receptor are called cardio selective because beta-1 is responsible for increasing heart rate; hence a beta blocker will slow the heart rate.

Class III agents (prolong repolarization by blocking outward K+ current): [[amiodarone]] and [[sotalol]] are effective class III agents. [[Ibutilide]] is another Class III agent but has a different mechanism of action (acts to promote influx of sodium through slow-sodium channels). It has been shown to be effective in acute cardioversion of recent-onset atrial fibrillation and atrial flutter.

Class IV drugs are calcium (Ca) channel blockers. They work by inhibiting the action potential of the SA and AV nodes.

If the patient is stable, [[adenosine]] may be used for restoration of sinus rhythm in patients with macro-reentrant supraventricular tachycardias. It causes a short-lived cessation of conduction through the atrio-ventricular node breaking the circus movement through the node and the macro-reentrant pathway restoring sinus rhythm.