Proarrhythmia 1723198 168098618 2007-10-30T15:56:52Z Magioladitis 1862829 link repair ([[Wikipedia:WikiProject Red Link Recovery|You can help!]]) '''Proarrhythmia''' is a new or more frequent occurrence of pre-existing [[arrhythmia]]s, paradoxically precipitated by antiarrhythmic therapy, which means it is a side-effect associated with the administration of some existing antiarrhythmic drugs, as well as drugs for other indications. In other words, it is a tendency of antiarrhythmic drugs to facilitate emergence of new arrhythmias. ==Types of Proarrhythmia== According to the [[Vaughan Williams classification]] (VW) of [[antiarrhythmic]] drugs, there are 3 main types of Proarrhythmia during treatment with various antiarrhythmic drugs for [[Atrial Fibrillation]] or [[Atrial flutter]]: ===Ventricular proarrhythmia=== *[[Torsade de pointes]] (VW type IA and type III drugs) *Sustained [[monomorphic ventricular tachycardia]] (usually VW type IC drugs) *Sustained [[polymorphic ventricular tachycardia]]/[[ventricular fibrillation]] without long QT (VQ types IA, IC, and III drugs) ===Atrial proarrhythmia=== *Conversion of atrial fribrillation to flutter (usually VW type IC drugs or amiodarone). May be a desired effect. *Increase of [[defibrillation threshold]] (a potential problem with VW type IC drugs) *Provocation of recurrence (probably VW types IA, IC and III drugs). It is rare. ===Abnormalities of conduction or impulse formation=== *[[Sinus node]] dysfunction, [[atrioventricular block]] (almost all drugs) *Accelerate conduction over accessory pathway ([[digoxin]], intravenous [[verapamil]], or [[diltiazem]]) *Acceleration of [[ventricular rate]] during atrial fibrillation (VW type IA and type IC drugs). ==Increased risk== *Presence of [[structural heart disease]], especially [[LV systolic dysfunction]]. *Class IC agents. *Increased age. *Females. ==Clinical pointers== ===Class IA drugs=== *Dose independent, occurring at normal levels. *Follow QT interval, keep ms. ===Class IC drugs=== *May be provoked by increased heart rate. *Exercise stress tests after loading. ===Class III drugs=== *Dose dependent. *Follow bradycardia, prolonged QT closely. ==External links== *[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9737654&dopt=Abstract Mechanisms and management of proarrhythmia] [[Category:Diseases]] {{disease-stub}}