title: Cryosurgical ablation of fetal atrioventricular node: new model to treat fetal malignant tachyarrhythmias.
abstract: BACKGROUND
  Sustained tachyarrhythmia resulting in fetal hydrops is often refractory to medical therapy. Fetal atrioventricular node ablation associated with epicardial fetal pacing has the potential to be an effective procedure for this morbid association.
  
  
  METHODS
  To assess the feasibility of therapeutic fetal heart block, we developed a technique of intrauterine cryosurgical ablation of fetal atrioventricular node without the need for cardiac bypass in 8 fetal lambs. Complete heart block was obtained by applying the cryoprobe over the coronary sinus. Fetal pacing was then performed to allow fetal survival.
  
  
  RESULTS
  Complete heart block was achieved in 100% of the fetal lambs. Postoperative evaluation revealed persistent atrioventricular block. The hearts were studied at different postoperative times. Morphologic evaluation of the area containing the cryosurgical lesion revealed varied extension of necrosis of the atrioventricular node and hemorrhage, with involvement of the His bundle and proximal right bundle branch.
  
  
  CONCLUSIONS
  This procedure is technically feasible and offers an alternative approach to the treatment of drug-resistant, life-threatening fetal supraventricular tachyarrhythmias associated with hydrops fetalis.
authors.affiliation: Heart Institute University of Sao Paulo Medical School, Brazil.
authors.forename: R S
authors.initials: RS
authors.lastname: Assad
authors.forename: V D
authors.initials: VD
authors.lastname: Aiello
authors.forename: M B
authors.initials: MB
authors.lastname: Jatene
authors.forename: R
authors.initials: R
authors.lastname: Costa
authors.forename: F L
authors.initials: FL
authors.lastname: Hanley
authors.forename: A D
authors.initials: AD
authors.lastname: Jatene
mesh_terms: D000818:Animals; D001283:Atrioventricular Node / Q000473:pathology / Q000601:surgery*; D003452:Cryosurgery; D004195:Disease Models, Animal; D005240:Feasibility Studies; D005315:Fetal Diseases / Q000601:surgery; D005318:Fetal Heart / Q000601:surgery*; D009336:Necrosis; D012756:Sheep; D013617:Tachycardia, Supraventricular / Q000601:surgery