title: Use of transesophageal echocardiography in radiofrequency catheter ablation in children and adolescents.
abstract: OBJECTIVE
  To assess the utility of transesophageal echocardiography (TEE) in radiofrequency (RF) catheter ablation of left-sided atrioventricular bypass tracts.
  
  
  METHODS
  RF catheter ablation was assisted with TEE in 13 children and adolescents aged 9.9 to 16.3 years (mean 13.3). Results were compared with 21 procedures done in 19 patients (age 8.8 to 18 years, mean 14.5) without TEE assistance.
  
  
  RESULTS
  RF ablation success rate was similar in both groups (90% to 92%). Successful RF ablation required 6 +/- 8 RF pulses in the TEE group and 10 +/- 7 RF pulses in the non-TEE group (nonsignificant). Fluoroscopy time was 36 +/- 17 mins and 54 +/- 28 mins, respectively (P = 0.03). Characteristic tenting of the fossa ovalis by a transseptal needle was easily visualized with TEE. TEE allowed for precise positioning of the ablation electrode on the mitral valve ring. At the successful site, the ventriculoatrial (VA) time was 42 +/- 10 ms in the TEE group and 52 +/- 16 ms in the non-TEE group (P = 0.05). The atrioventricular (A:V) ratio was 1.1 +/- 1.1 and 1.2 +/- 0.7, respectively (nonsignificant) with a large scatter of individual values. Electrogram amplitudes and VA conduction times that are desirable for RF ablation were also recorded on the mitral valve leaflets and over the coronary sinus. TEE visualized thrombus formation in the right atrium (three patients) and in the left atrium (two patients).
  
  
  CONCLUSIONS
  TEE should be strongly considered as supplemental imaging for RF ablation of left-sided bypass tracts performed under general anesthesia in children and adolescents. TEE renders transseptal puncture safe. TEE may decrease fluoroscopic exposure. TEE confirmation of the ablation catheter tip in the angle between the coronary sinus and the mitral valve ring may allow limitation of unnecessary RF lesions and injury to the mitral valve. The demonstration of early intracardiac thrombus formation argues for prompt and full heparinization after transseptal puncture.
authors.affiliation: Department of Pediatrics, University of Alberta, Edmonton. mkantoch@cha.ab.ca
authors.forename: M J
authors.initials: MJ
authors.lastname: Kantoch
authors.forename: G F
authors.initials: GF
authors.lastname: Frost
authors.forename: M A
authors.initials: MA
authors.lastname: Robertson
mesh_terms: D000293:Adolescent; D001283:Atrioventricular Node / Q000601:surgery; D002036:Bundle of His / Q000601:surgery; D017115:Catheter Ablation / Q000295:instrumentation*; D002648:Child; D017548:Echocardiography, Transesophageal / Q000295:instrumentation*; D004867:Equipment Design; D004869:Equipment Safety; D005260:Female; D006325:Heart Atria / Q000000981:diagnostic imaging / Q000601:surgery; D006346:Heart Septum / Q000000981:diagnostic imaging / Q000601:surgery; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000601:surgery; D006801:Humans; D008297:Male; D011183:Postoperative Complications / Q000000981:diagnostic imaging; D011677:Punctures / Q000295:instrumentation; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000000981:diagnostic imaging / Q000601:surgery*; D013927:Thrombosis / Q000000981:diagnostic imaging; D016896:Treatment Outcome