Interaction between vascular prostheses and rifampicin in the prevention of the grafts infection. An experimental study.

Infections caused by synthetic prostheses are relatively rare (1.5-6%) but serious complication in vascular surgery. There is no doubt that during and immediately after surgery bacterial contamination may occur. An in vitro study was carried out in the Vascutek laboratories, which revealed a high affinity between prostheses in Dacron gel and Rifampicin. This affinity, the result of an ionic bond, was demonstrated by the fact that after 5 days Rifampicin was still present on the prostheses. Encouraged by this result, an experimental study was carried out in sheep. Five sheep were operated on making a prosthetic graft in both of the common carotid arteries: on one side a Gelseal Dacron prosthesis was implanted after being soaked for 15 minutes in a solution containing 1 mg/ml Rifampicin. A Knitted Dacron prosthesis was implanted in the contralateral carotid artery, again after pretreatment with Rifampicin. Explants were made after 2, 24, 48, 72 and 96 hours, and the concentration of Rifampicin on the prostheses was assessed on the basis of the diameter of the inhibition area on Staphylococcus aureus cultures. The results showed that the Gelseal Dacron prostheses maintained Rifampicin concentrations with an antibacterial activity up to 72 hours; this property disappears with the Knitted Dacron prostheses after only 24 hours. These results confirm the high affinity of Gelseal Dacron and Rifampicin also in in vivo experimental models.

Early and long-term results in the surgical treatment of juxtarenal and pararenal aortic aneurysms.

OBJECTIVE: Surgical treatment of juxtarenal and pararenal aortic aneurysms (JPAA) provide technical problems which may influence short- and long-term results; however few surgical series have been published on this subject. The purpose of this study is to observe predictors of results in a series of JPAA and to analyse long-term survival of these patients. DESIGN, MATERIALS AND METHODS: Patients' epidemiology and surgical technique used in all cases of JPAA were reviewed and correlated with early results through logistic regression analysis. Early results were compared with those of infrarenal aneurysms (IAA) treated in the same period. Long-term results were obtained through our surveillance protocol (3 months after surgery and yearly thereafter) and calculated by life-table analysis. RESULTS: Fifty JPAA were identified over a total of 1450 aortic aneurysms (3.4%). Surgical approach was: anterior transperitoneal in 38 cases (96%), extended retroperitoneal in one (2%) and thoracoabdominal in one (2%). Suprarenal control was obtained in all cases; at the diaphragm in seven (14%), above both renal arteries in 17 (34%) and above one renal artery in 16 cases (32%). Renal revascularisation was performed in 11 cases (22%; nine unilateral and two bilateral). Overall perioperative mortality was 12%, significantly greater than mortality of IAAs: 50/1400, 3.5% (p < 0.02). Mortality in elective cases was 3/42, 7.1% and in ruptured JPAA 3/8, 37.5%. Independent predictors of early mortality were aneurysm rupture, age > 70 years, and coronary artery disease. Gender, smoking, hypertension, diabetes mellitus, site of proximal aortic clamping, type of aortic reconstruction, visceral revascularisation, and technically difficult cases were not associated with early mortality. Three and five year survivals were 66.8% +/- 9.93 and 40.0% +/- 12.64, respectively. CONCLUSIONS: Surgical treatment of JPAAs is associated with a higher risk of early mortality compared to IAAs and reduced long-term survival. Indications for surgery in JPAAs should consider the risk/benefit ratio rather than focusing on technical aspects which do not seem to significantly influence results.