title: Influence of open surgical correction on intermediate-term outcome in dogs with subvalvular aortic stenosis: 44 cases (1991-1998).
abstract: OBJECTIVE
  To compare outcome and intermediate-term survival for dogs undergoing open surgical correction of subvalvular aortic stenosis (SAS) with those for dogs with SAS that did not undergo surgery.
  
  
  METHODS
  Retrospective study.
  
  
  METHODS
  44 dogs with congenital SAS.
  
  
  METHODS
  Maximum instantaneous systolic pressure gradients were determined by use of Doppler echocardiography. Cardiopulmonary bypass and open surgical correction of SAS (membranectomy with or without septal myectomy) was performed in 22 dogs, whereas 22 dogs did not undergo surgical correction. Cumulative survival was compared between surgical and nonsurgical groups, using Kaplan-Meier nonparametric analysis and a Mantel-Cox log-rank test.
  
  
  RESULTS
  Initial systolic pressure gradients were not significantly different for dogs undergoing surgery (128 +/- 55 mm Hg), compared with those that did not undergo surgery (117 +/- 57 mm Hg). Systolic pressure gradients were significantly decreased after surgery in dogs that underwent surgery (54 +/- 27 mm Hg). Cumulative survival was not significantly different between dogs in the surgical and nonsurgical groups. Censoring surgery-related mortality in the analysis still did not reveal a significant difference in cumulative survival between the surgical and nonsurgical groups.
  
  
  CONCLUSIONS
  Despite reductions in the systolic pressure gradient and possible associated improvement in exercise tolerance, a palliative benefit on survival was not documented in dogs undergoing surgery for SAS.
authors.affiliation: Veterinary Teaching Hospital, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins 80523, USA.
authors.forename: E C
authors.initials: EC
authors.lastname: Orton
authors.forename: G D
authors.initials: GD
authors.lastname: Herndon
authors.forename: J A
authors.initials: JA
authors.lastname: Boon
authors.forename: J S
authors.initials: JS
authors.lastname: Gaynor
authors.forename: T B
authors.initials: TB
authors.lastname: Hackett
authors.forename: E
authors.initials: E
authors.lastname: Monnet
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use; D000818:Animals; D001020:Aortic Stenosis, Subvalvular / Q000151:congenital / Q000401:mortality / Q000601:surgery / Q000662:veterinary*; D001262:Atenolol / Q000627:therapeutic use; D001794:Blood Pressure; D002315:Cardiopulmonary Bypass / Q000662:veterinary; D004283:Dog Diseases / Q000151:congenital / Q000401:mortality* / Q000601:surgery*; D004285:Dogs; D015150:Echocardiography, Doppler / Q000662:veterinary; D006346:Heart Septum / Q000601:surgery; D012189:Retrospective Studies; D016019:Survival Analysis; D016896:Treatment Outcome
chemical_list: D000319:Adrenergic beta-Antagonists; D001262:Atenolol