An approach to the patient with a suspected tachycardia in the emergency department

Patients present to the emergency department with either an ongoing tachycardia or a history suspicious of a tachycardia. Either way, thetachycardia needs to be documented, preferably on a 12-lead electrocardiogram (ECG) for diagnosis and management. If a tachycardiais not documented, a careful history of the palpitations should be taken to see if further monitoring and investigations are required. If atachycardia is confirmed on an ECG, the clinician needs to classify it according to two variables: (i) regularity of the rhythm; and (ii) QRSwidth. This will allow a differential diagnosis to be made