Valved apico-aortic conduit for relief of left ventricular hypertension caused by discrete subaortic stenosis in dogs.

A double-outlet left ventricle (LV), with a valved conduit interposed between the LV apex and the aorta, was created in 7 dogs with subaortic stenosis. Of 8 dogs in which the implantation was attempted, 1 died following thoracotomy but before conduit implantation could be performed, 1 died from hemorrhage 24 hours after surgery, 1 died from septicemia as a sequel to pneumonia 10 days after surgery, 1 died from "shock-lung" 4 days after surgery, and 4 were functionally normal 22, 12, 6, and 2 months after surgery. In the 7 dogs in which the implantation was completed, the mean LV to aorta (LV-Ao) pressure gradient was significantly (P less than 0.01) reduced by the implantation. Diastolic and systolic murmurs were detected over the prosthetic valve area in 3 of the 4 surviving dogs 1 to 4 days postoperatively, but the murmurs gradually decreased in intensity until they disappeared after 1 month. The 4 survivors had no angiographic evidence of prosthetic valve insufficiency at 2 months or at 1 year. In 3 of the survivors, the LV-Ao pressure gradients 2 months postoperatively were 45, 20, and 0 mm of Hg, as compared with 120, 90, and 50 mm of Hg preoperatively. Postoperative pressure measurements were not obtained on 1 surviving dog.