Influence of open surgical correction on intermediate-term outcome in dogs with subvalvular aortic stenosis: 44 cases (1991–1998)

Objective—To compare outcome and intermediateterm survival for dogs undergoing open surgical correction of subvalvular aortic stenosis (SAS) with those for dogs with SAS that did not undergo surgery. Design—Retrospective study. Animals—44 dogs with congenital SAS. Procedure—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). ...