title: Determination of inadvertent atrial capture during para-Hisian pacing.
abstract: BACKGROUND
  Inadvertent capture of the atrium will lead to spurious results during para-Hisian pacing. We sought to establish whether the stimulation-to-atrial electrogram interval at the proximal coronary sinus (stim-PCS) or high right atrium (stim-HRA) could signal inadvertent atrial capture.
  
  
  RESULTS
  Para-Hisian pacing with and without intentional atrial capture was performed in 31 patients. Stim-HRA and stim-PCS intervals were measured with atrial capture, His plus para-Hisian ventricular (H+V) capture, and para-Hisian ventricular (V) capture alone. The mean stim-HRA interval was significantly shorter with atrial capture (66 ± 18 ms) than with H+V (121 ± 27 ms, P < 0.001) or V capture alone (174 ± 38 ms, P < 0.001). The mean stim-PCS interval was significantly shorter with atrial capture (51 ± 16 ms) than with H+V (92 ± 22 ms, P<0.001) or V capture alone (146 ± 33 ms, P < 0.001). A stim-PCS < 60 ms (stim-HRA < 70 ms) was observed only with atrial capture. A stim-PCS >90 ms (stim-HRA >100 ms) was observed only in the absence of atrial capture. A stim-HRA of < 85 ms was highly specific and stim-PCS of < 85 ms highly sensitive at identifying atrial capture. Stim-HRA intervals of 75 to 97 ms and stim-PCS intervals of 65 to 88 ms were observed with either atrial, His, or para-Hisian ventricular capture without atrial capture. In this overlap zone, all patients demonstrated a stim-PCS or stim-HRA interval prolongation of at least 20 ms when the catheter was advanced to avoid deliberate atrial pacing. The QRS morphology was of limited value in distinguishing atrial capture due to concurrent ventricular or H+V capture, as observed in 20 of 31 (65%) patients.
  
  
  CONCLUSIONS
  Stim-PCS and stim-HRA intervals can be used to monitor for inadvertent atrial capture during para-Hisian pacing. A stim-PCS < 60 ms (or stim-HRA < 70 ms) and stim-PCS > 90 ms (or stim-HRA > 100 ms) were observed only with and without atrial capture, respectively, but there was significant overlap between these values. Deliberate atrial capture and loss of capture reliably identifies atrial capture regardless of intervals.
authors.affiliation: Division of Cardiology, University of Western Ontario, London, Ontario, Canada. manojobey@yahoo.com
authors.forename: Manoj
authors.initials: M
authors.lastname: Obeyesekere
authors.forename: Peter
authors.initials: P
authors.lastname: Leong-Sit
authors.forename: Allan
authors.initials: A
authors.lastname: Skanes
authors.forename: Andrew
authors.initials: A
authors.lastname: Krahn
authors.forename: Raymond
authors.initials: R
authors.lastname: Yee
authors.forename: Lorne J
authors.initials: LJ
authors.lastname: Gula
authors.forename: Matthew
authors.initials: M
authors.lastname: Bennett
authors.forename: George J
authors.initials: GJ
authors.lastname: Klein
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002036:Bundle of His / Q000503:physiopathology*; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D054326:Coronary Sinus / Q000503:physiopathology; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006325:Heart Atria / Q000503:physiopathology*; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012372:ROC Curve; D013617:Tachycardia, Supraventricular / Q000503:physiopathology / Q000628:therapy*; D013997:Time Factors; D055815:Young Adult