Efficacy of muscle flaps in the treatment of prosthetic vascular graft infections.

Prosthetic vascular graft infection requires graft removal and often leads to limb loss. To determine whether vascularized muscle flaps could alter the course of graft infection, 18 mongrel dogs (18-29 kg) were randomized to one of three groups and underwent unilateral carotid artery bypass with 6-mm X 4-cm PTFE grafts. At implantation, the grafts were inoculated with Staphylococcus aureus, 2 x 10(7) organisms/wound. On Day 3, dogs with patent grafts underwent wound debridement, irrigation, and closure, and the treatment to which they had been randomized was carried out. Group A (n = 4, controls) received only dicloxacillin, 500 mg po bid, beginning on Day 4. Group B (n = 5) underwent transfer of a vascularized sternocephalicus muscle flap around the infected graft, but received no antibiotics. Group C (n = 5) underwent muscle transfer as in Group B and were given dicloxacillin as in Group A. Dogs were followed until anastomotic disruption occurred or for 60 days. Quantitative bacterial cultures were taken from sternocephalicus muscle and wound fluid at the time of debridement and at sacrifice. All dogs that received antibiotics without flaps or flaps without antibiotics (Groups A and B) experienced anastomotic disruption. Dogs that received both antibiotics and flaps (Group C) had a significantly lower incidence of hemorrhage (20%, P less than 0.05). At sacrifice, fewer bacterial colonies were cultured from muscle flaps of Group C as opposed to Group A dogs (0.05 +/- 0.02 x 10(5) vs 0.79 +/- 0.31 x 10(5), P less than 0.05). Muscle flaps with antibiotic therapy may prove to be effective treatment for infected prosthetic vascular grafts.

Effect of a selective thromboxane synthase inhibitor on arterial graft patency and platelet deposition in dogs.

This study examined the effect of selective thromboxane synthase inhibition and nonselective cyclooxygenase inhibition on vascular graft patency and indium 111-labeled platelet deposition in 35 mongrel dogs undergoing carotid artery replacement with 4 mm X 4 cm polytetrafluoroethylene (PTFE) (one side) and Dacron (opposite side) end-to-end grafts. Aspirin-dipyridamole therapy improved one-week graft patency, from 46% in untreated dogs to 93% in treated dogs. Thromboxane synthase inhibition (U-63557A) improved graft patency in these dogs to 81%. Both drug treatments reduced platelet deposition on Dacron and PTFE grafts by 48% to 68% compared with control dogs. Dacron grafts accumulated significantly more platelets than PTFE grafts but had comparable patency rates. Low-dose aspirin therapy had no significant effect on either graft patency or platelet deposition. All treatment groups showed a 60% to 76% reduction in serum thromboxane B2, but only thromboxane synthase inhibitor treatment increased plasma 6-keto-prostaglandin F1 alpha by 100%. Selective thromboxane synthase inhibition improved small-caliber prosthetic graft patency to the same extent as did conventional cyclooxygenase inhibition in this preliminary study.