Invited commentary

Abstract

This basic science study's goal is to address an area of clinical ambiguity: how to coat an endovascular stent graft with rifampin in a standard and optimized manner for immediate use in an infected field. It optimizes two variables, concentration and incubation period, in an ex vivo experiment and on the basis of the results suggests a rapid real-time perioperative protocol. The graft chosen to study is a standard Dacron endograft of various diameters and lengths. There are reports of using a rifampin-coated endograft in an infected field with preparation extrapolated from methods used during open operation (60 mg/mL rifampin incubated for 1 hour). A dedicated scientific study to determine optimal endograft coating would allow a more reasonable comparison of results when applied in the clinical condition. This study demonstrates that a rifampin solution of 10 mg/mL delivered as one 20-mL aliquot with an incubation time of 10 minutes will provide a well-coated endograft, not improved by higher concentrations or longer periods of intubation. This allows the surgeon to save both resources (drug, supplies) and time during an urgent or emergent case. An overnight bathing in methanol solvent demonstrates that the concentration or incubation time had no effect on the amount of rifampin trapped (coating) on the graft. Bathing in a saline bath demonstrates that the coated rifampin is essentially gone at 50 hours. The well-coated endograft does not retain as much rifampin as a similarly coated control graft, probably because the control graft is a gelatin-sealed graft. The endograft is not made with a gelatin coating, so the authors have no control of this processing step, and the comparison is somewhat artificial. As with most good basic research, more questions come to mind than are answered by the original work. This study does not evaluate the prepared graft under conditions that might greatly influence its performance in the clinical situation. The lack of evaluation in a flow chamber does not allow an estimate of rifampin loss over time from both the flow and sac surface. Dacron endografts generally leak through the material interstices until anticoagulation is reversed, so the loss may be rapid from both surfaces. Under such circumstances, what antimicrobial activity remains even minutes after deployment? In vivo animal experiments with implantation in an infected field would yield some estimate of the potential clinical impact of this method of in situ repair. Would presealing with a gelatin coating before rifampin coating better mimic the open scenario and improve the results? All these factors being considered, this study does provide a logical basic science first step to a clinical problem that can now be further studied to provide greater insight into its clinic use. The opinions or views expressed in this commentary are those of the authors and do not necessarily reflect the opinions or recommendations of the Journal of Vascular Surgery or the Society for Vascular Surgery Optimization of rifampin coating on covered Dacron endovascular stent grafts for infected aortic aneurysmsJournal of Vascular SurgeryVol. 69Issue 1PreviewIn the treatment of an infected aorta, open repair and replacement with a rifampin-impregnated Dacron vascular graft decrease the risk of prosthetic graft infections, with several protocols available in the literature. We hypothesize that the same holds true for endovascular aneurysm repair, and after studying and optimizing rifampin solution concentration and incubation period to maximize the coating process of rifampin on Dacron endovascular stent grafts (ESGs), we propose a rapid real-time perioperative protocol. Full-Text PDF Open Archive