* What is the '''[[Conduction|QRS width]]'''?
**If the QRS < 120ms (i.e. a narrow complex), then it is either a [[Sinus node rhythms and arrhythmias|sinus arrhythmia]], [[Supraventricular Rhythms|supraventricular rhythm]] or a [[Junctional Tachycardias|junctional tachycardia]]. In tachycardias, this [[Media:Svt_algorythm_en.png|'''flowchart''']] will lead to the right diagnosis.<cite>ESCnarrowQRS</cite>
**If the QRS > 120ms it is either a [[Ventricular Arrhythmias|ventricular tachycardia]] or a [[Supraventricular Rhythms|supraventricular rhythm]] with additional [[Intraventricular Conduction|bundle branch block]]. This is a challenging
difficulty in arrhythmia diagnosis , therefore a [[media:wideQRS_tachycardia_flow.png|'''flowchart''']] might help, which incoporates the Brugada criteria for VT.<cite>Brugada</cite> Another method to discriminate VT from SVT has been proposed by Vereckei et al.<cite>vereckei</cite> In the editorial on that paper an excellent review is given on the subject by Dendi and Josephson.<cite>dendi</cite>
* What is the '''[[Heart axis|Heart Axis]]''' and did it change?
** If the heart axis turns significantly when compared to the heart axis during sinus rhythm a ventricular origin of the rhythm is more likely.