EKG Dictionary
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Rate, rhythm & mechanisms

Tachycardia

Also calledtachyarrhythmia · fast heart rate · tachy

Definition

A heart rate above 100 bpm in an adult. It is a rate descriptor, not a single diagnosis; tachycardias are further classified by QRS width (narrow-complex, QRS under 120 ms, versus wide-complex, described in the 2015 ACC/AHA/HRS SVT guideline as a QRS over 120 ms) and by whether the ventricular rhythm is regular or irregular, to identify the specific mechanism.

Sources

  1. Goodacre S, Irons R. ABC of clinical electrocardiography: atrial arrhythmias. BMJ. 2002;324(7337):594-597. doi.org/10.1136/bmj.324.7337.594
  2. Page RL, Joglar JA, Caldwell MA, et al. 2015 ACC/AHA/HRS guideline for the management of adult patients with supraventricular tachycardia. Circulation. 2016;133(14):e506-e574. doi.org/10.1161/CIR.0000000000000311
  3. Samesima N, God EG, Kruse JCL, et al. Brazilian Society of Cardiology guidelines on the analysis and issuance of electrocardiographic reports - 2022. Arq Bras Cardiol. 2022;119(4):638-680. doi.org/10.36660/abc.20220623

Last reviewed 2 October 2026. Every definition in the EKG Dictionary cites the guideline, consensus statement or original paper it comes from.

More in Rate, rhythm & mechanisms

Aberrant conduction Ashman phenomenon Asystole Automaticity AV dissociation Bradycardia Capture beat Compensatory pause Ectopic beat Escape beat Fusion beat Heart rate Irregularly irregular rhythm Normal sinus rhythm Pulseless electrical activity (PEA) Reentry Regular rhythm Regularly irregular rhythm Sinus arrhythmia

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