title: Para-Hisian entrainment: a novel pacing maneuver to differentiate orthodromic atrioventricular reentrant tachycardia from atrioventricular nodal reentrant tachycardia.
abstract: BACKGROUND
  Para-Hisian pacing during sinus rhythm can help to identify the presence of an accessory pathway (AP). In this maneuver, the retrograde activation time and pattern are compared during capture and loss-of-capture of the His bundle while pacing from a para-Hisian position. However, identification of a retrograde AP does not necessitate that it is operative during the tachycardia of interest; conversely, slowly conducting or "distant" bypass tracts may not be identified. We evaluated the utility of entrainment or resetting of tachycardias from the para-Hisian position to help distinguish atrioventricular nodal reentrant tachycardia (AVNRT) from orthodromic atrioventricular tachycardia (AVRT).
  
  
  RESULTS
  Para-Hisian entrainment/resetting was evaluated in 50 patients: 33 with AVNRT and 17 with AVRT. The maneuvers were performed using a standard quadripolar catheter placed at the His position: low output for right ventricular (RV) capture and high output for both RV and His capture. The retrograde atrial activation sequence, SA interval (interval from stimulus to earliest retrograde atrial activation), and "local" VA interval (interval between the ventricular and atrial electrograms at the site of earliest retrograde atrial activation) were compared between His and His/RV capture. The DeltaSA was > 40 ms in patients with AVNRT and was < 40 ms in all but one patient with AVRT. In concert with the DeltaSA interval, the DeltaVA interval was able to fully define the mechanism of the tachycardia in all patients studied.
  
  
  CONCLUSIONS
  Para-Hisian entrainment/resetting can determine the course of retrograde conduction operative during narrow complex tachycardias. It is a useful diagnostic maneuver in differentiating AVNRT and orthodromic AVRT.
authors.affiliation: Massachusetts General Hospital--Harvard Medical School, Boston, Massachusetts 02114, USA. vreddy@partners.org
authors.forename: Vivek Y
authors.initials: VY
authors.lastname: Reddy
authors.forename: Krit
authors.initials: K
authors.lastname: Jongnarangsin
authors.forename: Christine M
authors.initials: CM
authors.lastname: Albert
authors.forename: Hani
authors.initials: H
authors.lastname: Sabbour
authors.forename: David
authors.initials: D
authors.lastname: Keane
authors.forename: Theofanie
authors.initials: T
authors.lastname: Mela
authors.forename: Brian
authors.initials: B
authors.lastname: McGovern
authors.forename: Jeremy N
authors.initials: JN
authors.lastname: Ruskin
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001283:Atrioventricular Node / Q000503:physiopathology*; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D017115:Catheter Ablation; D003937:Diagnosis, Differential; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000145:classification* / Q000175:diagnosis* / Q000628:therapy