A Practical Criterion for the Rapid Detection of Single-Loop and Double-Loop Reentry Tachycardias


  • N. Linton is supported by a Medical Research Council Clinical Research Training Fellowship. N. Linton, M. Wright, and M. O'Neill acknowledge support from the UK Department of Health via the National Institute for Health Research comprehensive Biomedical Research Centre award to Guy's and St. Thomas' NHS Foundation Trust in partnership with King's College London and King's College Hospital NHS Foundation Trust. S.B. Wilton is supported by the Canadian Institutes of Health Research Randomized Controlled Trials Mentoring Program. Other authors: No disclosures.

Address for correspondence: Nick Linton, Arrhythmia Research, Division of Imaging Sciences, 3rd Floor, Lambeth Wing, St Thomas’ Hospital, London SE1 7EH, UK. Fax: +44-20-7188-5442; E-mail: nick@foxlinton.org

Additional Criterion for Entrainment


Entrainment criteria for the diagnosis of reentrant atrial tachycardia can be difficult to apply and cannot detect double-loop reentry. We sought to develop and clinically test a new criterion for the diagnosis of single- and double-loop reentry.

Methods and Results

(1) Proposed criterion: after sequential overdrive pacing at 2 different locations and assessing the first ensuing beats of tachycardia, the difference in activation time recorded between 2 appropriate stationary positions changes by 1 or 2 tachycardia cycle lengths; a change of 2 tachycardia cycle lengths usually indicates double-loop reentry rather than only a single-loop. (2) Clinical testing: multiple overdrive pacing maneuvers were undertaken and analyzed in 5 patients with common flutter (single-loop reentry). In total, 23 pairs of overdrive pacing maneuvers were performed using electrodes in the coronary sinus and a distribution of positions in the right atrium. In 22/23 pairs of maneuvers, the change in Activation Difference was within 2.6 ± 12.4 milliseconds of the tachycardia cycle length, confirming single loop reentry. For double-loop reentry, the literature was reviewed and 3 cases of double-loop reentry were identified with sufficient data. In all of these cases, double-loop reentry was detected and also the zone containing the common isthmus was identified.


The proposed criterion can diagnose single- and double-loop reentry atrial tachycardia using intracardiac recordings from any pair of well separated positions. The criterion does not require precise electrode placement or extensive activation mapping.