Editing Flecainide (section)

===Heart===
Due to the narrow therapeutic index of flecainide, physicians should be alert for signs of toxicity before life-threatening arrhythmias occur like [[torsades de pointes]]. While the toxic effects of flecainide are closely related to the plasma levels of the drug,<ref name = Winkelmann>{{cite journal | vauthors = Winkelmann BR, Leinberger H | title = Life-threatening flecainide toxicity. A pharmacodynamic approach | journal = Annals of Internal Medicine | volume = 106 | issue = 6 | pages = 807–814 | date = June 1987 | pmid = 3107447 | doi = 10.7326/0003-4819-106-6-807 }}</ref> it is unfeasible to check the plasma concentration in an individual on a regular basis.

Signs of flecainide toxicity include marked prolongation of the PR interval and widening of the QRS duration on the surface ECG. There may be signs and symptoms attributable to overt [[congestive heart failure|heart failure]] secondary to sudden decreased [[myocardial contractility]].

====Treatment====
Treatment of flecainide cardiac toxicity involves increasing the excretion of flecainide, blocking its effects in the heart, and (rarely) institution of cardiovascular support to avoid impending lethal arrhythmias. Modalities that have had success include administration of a beta-sympathomimetic agent,<ref name = Winkelmann/> and administration of a sodium load<ref name = Winkelmann/>(often in the form of [[Tonicity#Hypertonic solution|hypertonic]] [[sodium bicarbonate]]). Placing the individual on [[cardiopulmonary bypass]] support may be necessary in order to temporarily remove the need for a beating heart and to increase blood flow to the liver.<ref name = Corkeron>{{cite journal | vauthors = Corkeron MA, van Heerden PV, Newman SM, Dusci L | title = Extracorporeal circulatory support in near-fatal flecainide overdose | journal = Anaesthesia and Intensive Care | volume = 27 | issue = 4 | pages = 405–408 | date = August 1999 | pmid = 10470398 | doi = 10.1177/0310057x9902700413 | doi-access = free }}</ref><ref name = Yasui>{{cite journal | vauthors = Yasui RK, Culclasure TF, Kaufman D, Freed CR | title = Flecainide overdose: is cardiopulmonary support the treatment? | journal = Annals of Emergency Medicine | volume = 29 | issue = 5 | pages = 680–682 | date = May 1997 | pmid = 9140253 | doi = 10.1016/S0196-0644(97)70257-9 }}</ref>