title: First postpacing interval after tachycardia entrainment with correction for atrioventricular node delay: a simple maneuver for differential diagnosis of atrioventricular nodal reentrant tachycardias versus orthodromic reciprocating tachycardias.
abstract: BACKGROUND
  The difference between the first postpacing interval (PPI) after tachycardia entrainment from the right ventricular apex and the tachycardia cycle length (TCL) can be used as an index of proximity to the circuit.
  
  
  OBJECTIVE
  The purpose of this study was to determine whether the response to entrainment of tachycardia during ventricular stimulation with correction for AV node delay is a useful, simple maneuver for differentiating AV nodal reentrant tachycardia (AVNRT) from orthodromic reciprocating tachycardia (ORT) using a concealed accessory pathway.
  
  
  METHODS
  The study consisted of 193 consecutive patients who underwent electrophysiologic study and ablation of regular paroxysmal supraventricular tachycardia without preexcitation during sinus rhythm. Tachycardia entrainment was attempted through trains of 5 to 15 right ventricular apex pacing pulses. The increment in AV nodal conduction time in the first PPI was subtracted from the PPI-TCL difference (corrected PPI-TCL).
  
  
  RESULTS
  Electrophysiologic study demonstrated ORT in 84 patients and AVNRT in 109 patients. Transient entrainment was achieved in all but 12 patients. The mean corrected PPI-TCL difference was significantly shorter in 77 patients with ORT (66 +/- 27 ms) than in 104 AVNRT patients (151 +/- 28 ms; P <.0001). Patients with septal accessory pathways had shorter corrected PPI-TCL differences than patients with free-wall accessory pathways. The presence of a corrected PPI-TCL difference <110 ms identified all but one patient with ORT, and no patients with AVNRT had such a difference.
  
  
  CONCLUSIONS
  The return cycle after tachycardia entrainment by right ventricular apex stimulation with correction for AV node delay is a rapid, useful maneuver for differential diagnosis of AVNRT vs ORT in patients without preexcitation. The presence of a corrected PPI-TCL <110 ms accurately identified with high reliability those patients with ORT.
authors.affiliation: Cardiology Department, Hospital General Universitario Gregorio Marañón, Madrid, Spain. etorrecilla@telefonica.net
authors.forename: Esteban
authors.initials: E
authors.lastname: González-Torrecilla
authors.forename: Angel
authors.initials: A
authors.lastname: Arenal
authors.forename: Felipe
authors.initials: F
authors.lastname: Atienza
authors.forename: Joaquin
authors.initials: J
authors.lastname: Osca
authors.forename: Javier
authors.initials: J
authors.lastname: García-Fernández
authors.forename: Alberto
authors.initials: A
authors.lastname: Puchol
authors.forename: Ana
authors.initials: A
authors.lastname: Sánchez
authors.forename: Jesús
authors.initials: J
authors.lastname: Almendral
mesh_terms: D000328:Adult; D002304:Cardiac Pacing, Artificial; D003937:Diagnosis, Differential; D004562:Electrocardiography; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology; D006801:Humans; D008297:Male; D011237:Predictive Value of Tests; D011446:Prospective Studies; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000175:diagnosis* / Q000503:physiopathology; D013614:Tachycardia, Paroxysmal / Q000175:diagnosis* / Q000503:physiopathology; D013997:Time Factors