Editing Tachycardia (section)

=====Atrial fibrillation=====
[[Atrial fibrillation]] is one of the most common cardiac arrhythmias. In general, it is an irregular, narrow complex rhythm. However, it may show wide QRS complexes on the ECG if a [[bundle branch block]] is present. At high rates, the QRS complex may also become wide due to the [[Ashman phenomenon]]. It may be difficult to determine the rhythm's regularity when the rate exceeds 150 beats per minute. Depending on the patient's health and other variables such as medications taken for rate control, atrial fibrillation may cause heart rates that span from 50 to 250 beats per minute (or even higher if an [[Wolff-Parkinson-White syndrome|accessory pathway]] is present). However, new-onset atrial fibrillation tends to present with rates between 100 and 150 beats per minute.<ref>{{cite web | vauthors = Oiseth S, Jones L, Maza E |url= https://www.lecturio.com/concepts/atrial-fibrillation/ | title= Atrial Fibrillation | website= The Lecturio Medical Concept Library | date= 11 August 2020 |access-date= 3 July 2021}}</ref>