title: Usefulness of interatrial conduction time to distinguish between focal atrial tachyarrhythmias originating from the superior vena cava and the right superior pulmonary vein.
abstract: OBJECTIVE
  Differentiation of the tachycardia originating from the superior vena cava (SVC) or the right superior pulmonary vein (RSPV) is limited by the similar surface P-wave morphology and intraatrial activation pattern during tachycardia. We sought to find a simple method to distinguish between the two tachycardias by analyzing the interatrial conduction time.
  
  
  METHODS
  Sixteen consecutive patients consisting of 8 with SVC tachycardia and the other 8 with RSPV tachycardia were studied. The interatrial conduction time from the high right atrium (HRA) to the distal coronary sinus (DCS) and the intraatrial conduction time from the HRA to the atrial electrogram at the His bundle region (HIS) were measured during the sinus beat (SR) and during the tachycardia-triggering ectopic atrial premature beat (APB). The differences of interatrial (Delta[HRA-DCS](SR-APB)) and intraatrial (Delta[HRA-HIS](SR-APB)) conduction time between SR and APB were then obtained.
  
  
  RESULTS
  The mean Delta[HRA-DCS](SR-APB) was 1.0 +/- 5.2 ms (95% confident interval [CI]-3.3-5.3 ms) in SVC tachycardia and 38.5 +/- 8.8 ms (95% CI 31.1-45.9 ms) in RSPV tachycardia. The mean Delta[HRA-HIS](SR-APB) was 1.5 +/- 5.3 ms (95% CI -2.9-5.9 ms) in SVC tachycardia and 19.9 +/- 12.0 ms (95% CI 9.9-29.9 ms) in RSPV tachycardia. The difference of Delta[HRA-DCS](SR-APB) between SVC and RSPV tachycardias was wider than that of Delta[HRA-HIS](SR-APB) (37.5 +/- 9.3 ms vs. 18.4 +/- 15.4 ms, P < 0.01).
  
  
  CONCLUSIONS
  The wide difference of the interatrial conduction time Delta[HRA-DCS](SR-APB) between SVC and RSPV tachycardias is a useful parameter to distinguish the two tachycardias and may avoid unnecessary atrial transseptal puncture.
authors.affiliation: Graduate Institute of Clinical Medical Science, China Medical University, Taichung, Taiwan.
authors.forename: Kuan-Cheng
authors.initials: KC
authors.lastname: Chang
authors.forename: Jan-Yow
authors.initials: JY
authors.lastname: Chen
authors.forename: Yu-Chin
authors.initials: YC
authors.lastname: Lin
authors.forename: Shoei K Stephen
authors.initials: SK
authors.lastname: Huang
mesh_terms: D000328:Adult; D000368:Aged; D018780:Body Surface Potential Mapping / Q000379:methods*; D003937:Diagnosis, Differential; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009431:Neural Conduction; D011667:Pulmonary Veins / Q000502:physiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013612:Tachycardia, Ectopic Atrial / Q000175:diagnosis* / Q000503:physiopathology*; D014683:Vena Cava, Superior / Q000503:physiopathology*