RESECTION OF SUBVALVULAR AORTIC-STENOSIS - SURGICAL AND PERIOPERATIVEMANAGEMENT IN 7 DOGS

Open heart surgery was performed during cardiopulmonary bypass (CPB) t o surgically correct subvalvular aortic stenosis in seven dogs. After initiation of total CPB, cardiac arrest was induced by antegrade and r etrograde administration of blood cardioplegia. The subvalvular fibrou s stenosis was resected through a transverse aortotomy. Intraoperative ly and postoperatively, dobutamine, nitroprusside, lidocaine, blood(-p roducts), and crystalloid solutions were used to manage hypotension an d optimize cardiac index. Aortic cross-clamp time varied from 73 to 16 6 minutes, and duration of CPB varied from 130 to 210 minutes. Iatroge nic incision into the mitral valve in two dogs was the most significan t introperative complication. Postoperative complications included: hy poproteinemia (n = 7), premature ventricular depolarization (n = 6), i ncreased systemic vascular resistance index (n = 5), increased O2 extr action (n = 3), pulmonary edema (n = 2), and decreased cardiac index ( n = 1). All seven dogs were discharged alive and in stable condition. Six dogs are alive and in stable condition after a mean follow up of 1 5.8 months. This is the first detailed report of CPB in a series of cl inical veterinary patients. Using the techniques described in this pap er, open heart surgery of considerable duration can be performed succe ssfully in dogs with significant myocardial hypertrophy and endomyocar dial fibrosis secondary to subvalvular aortic stenosis.