Prosthetic Vascular Graft Research Articles

Neuraminidase decreases in vitro adherence of slime-forming coagulase-negative staphylococci to biosynthetic ovine collagen vascular graft

Vascular prosthetic graft infection is a major complication of vascular surgery that starts with adhesion of the microorganism to the graft. Because slime-forming microorganisms are the major causative agents in graft infection, the goals of investigators in this study were (1) to investigate the bacterial adherence of slime-forming and non-slime-forming coagulase-negative staphylococci (CNS), and (2) to determine the role of neuraminidase (NANase) in bacterial adherence to the biosynthetic ovine collagen graft. Human plasma was instilled and incubated at 37 degrees C in preparation for fibrin deposition of grafts. After 48 hours, incubation grafts were drained and inoculated with slime-forming and non-slime-forming CNS in tryptic soy broth in the presence and in the absence of neuraminidase. After 24 hours of incubation at 36 degrees C, grafts were vortexed and cultured for colony count. Bacterial counts were expressed as total colony-forming units per longitudinal centimeter of the graft. Slime-forming CNS had greater affinity to the collagen graft compared with non-slime-forming CNS (P<.05). Adherence of slime-forming CNS was impaired by NANase treatment (P<.001). NANase treatment of patients with non-slime-forming CNS did not change adherence to the graft (P>.05). Results show that slime plays an important role in the pathogenesis of vascular graft infection. Adherence of slime-forming CNS can be decreased through the administration of NANase. This may have implications for the development of neuraminidase-embedded vascular grafts designed to reduce the occurrence of biomaterial-related infection.

Synthetic smooth muscle cell phenotype is associated with increased nicotinamide adenine dinucleotide phosphate oxidase activity: Effect on collagen secretion

Smooth muscle cells (SMCs) from prosthetic vascular grafts secrete higher levels of collagen than aortic SMCs under basal conditions and during incubation with oxidized low-density lipoprotein. We postulated that reactive oxygen species (ROS) contributed to the observed difference. The objective of this study was to assess the effect of ROS on collagen secretion by aortic and graft SMCs and explore the mechanism involved. SMCs isolated from canine aorta or Dacron thoracoabdominal grafts were incubated with 6-anilinoquinoline-5,8-quinone (LY83583), an agent that induces superoxide production. Type I collagen in the conditioned medium was measured by enzyme-linked immunosorbent assay, and superoxide anion production was measured by lucigenin assay. LY83583 stimulated a rapid increase in collagen production by graft SMCs that paralleled the LY83583-induced increase in superoxide production. The increase in both collagen and superoxide was greater in graft SMCs than aortic SMCs. Collagen and superoxide production were inhibited by superoxide scavengers. Nicotinamide adenine dinucleotide phosphate (NADPH) induced significantly more superoxide production by graft SMCs than aortic SMCs, suggesting that the NADPH oxidase system was more active in graft SMCs. NADPH oxidase inhibitors blocked the superoxide and collagen production induced by LY83583. In SMCs, the synthetic phenotype is associated with increased NADPH oxidase activity and elevated superoxide production in response to an oxidative stress. Superoxide, in turn, leads to increased collagen production. The inflammatory process after prosthetic vascular graft implantation causes oxidative stress that can stimulate collagen production by graft SMCs, contributing to the progression of intimal hyperplasia. The exaggerated response of graft SMCs to oxidative stress offers a potential target for therapeutic interventions.

Paint-Only is Equivalent to Scrub-and-Paint in Preoperative Preparation of Abdominal Surgery Site

Conclusion: A paint with povidone-iodine by itself provides equal preoperative preparation of the abdominal wall as a scrub with povidone-iodine soap, followed by paint with povidone-iodine. Summary: The authors conducted a prospective randomized trial comparing scrub-and-paint with povidone-iodine soap followed by absorption with a sterile towel and subsequent paint with povidone-iodine versus surgical site preparation with paint only of povidone-iodine. The primary end point was wound infection at 30 days with wound infection defined as clinical signs of infection requiring therapeutic intervention. Excluded patients included those with active infection at the time of operation, known sensitivity to iodine, neutropenia, or insertion of prosthetic material during operation. Patients were randomized to a scrub-and-paint group or a paint only group with povidone-iodine. There were 115 patients randomized to the scrub-and-paint arm and 119 to the paint only arm of the trial. Patients were well matched with respect to surgical co-morbidities, age, operative time, drains, surgical procedure, and prophylactic antibiotic use. There were 12 wound infections in the scrub-and-paint patients (10%) and 12 wound infections in the paint only patients (10%). Comment: These data apply only to clean and clean-contaminated cases that do not involve placement of a prosthetic device. While the data are interesting, they do not provide guidance as to the proper surgical prep site technique for patients undergoing insertion of prosthetic grafts. The optimal surgical prep site technique with respect to insertion of prosthetic vascular grafts remains to be determined.

Infective Endocarditis in Congenital Heart Disease Patients: It's Time to Pay More Attention!

Infective endocarditis(IE) is the result of endovascular microbial infection. Due to the growing patient population suffering with preand postoperative congenital heart disease(CHD), the increased placement of prosthetic valves, vascular grafts and patches in the heart and also the improvement of intensive cardiac care, IE that is related to CHD is showing continuously changing features. In general, IE can be better classified by referring to the activity of the disease, the diagnostic status(definite/possible), the anatomic site(right/left side), the underlying disease(native valve/prosthetic valve/other foreign material), the microbiology of the disease(the causative microorganism and the culture/ serology/PCR/histology) and the patient population (CHD, nosocomial IE, drug users, hemodialysis, etc.).

Long-term home-based parenteral antibiotic treatment of a prosthetic vascular graft infection caused by Pseudomonas aeruginosa

Survival for more than 5 y was obtained with home-based parenteral antibiotic therapy in a 68-y-old male with Pseudomonas aeruginosa infection of an aortic-bifemoral prosthetic graft. Surgical intervention was deemed to carry to high a risk and we suggest that lifelong suppressive antibiotic therapy may be an option in selected patients.

Cyanoacrylate for Wound Closure in Prosthetic Vascular Graft Surgery to Prevent Infections Through Contamination

Prosthetic vascular graft infection (PVGI) still occurs at an unacceptably high rate, despite the many measures that have proven effective against infection. The major cause of PVGI is perioperative contamination, which usually occurs before a histological barrier is completed and may threaten graft viability. We assessed the efficacy of cyanoacrylate as a tissue adhesive and barrier against early contamination through the skin. A 1 x 0.5-cm Dacron graft was placed subcutaneously under sterile conditions in 16 Sprague-Dawley rats. The skin was closed with polypropylene sutures in eight rats (group A) and with N-butyl 2-cyanoacrylate in eight rats (group B). The closed incisions were then contaminated with 75 x 10(6) cfu/ml methicillin-sensitive Staphylococcus aureus. Microbiological and histopathological assessments were done 7 days later, after the rats were killed. All of the graft cultures from group A (8/8) were positive for S. aureus whereas all of those from group B (0/8) were negative. This difference was significant (p < 0.001). Histological examination revealed denser inflammatory cell infiltration in group A than in group B. Maintaining skin integrity after closure is of the utmost importance because contamination during the first hours of the procedure may cause PVGI. Cyanoacrylate seems to be a promising molecule not only because of its bacteriostatic effects, but also because it seals the barrier effectively and immediately.

Efficacy of Vancomycin, Teicoplanin and Fusidic Acid as Prophylactic Agents in Prevention of Vascular Graft Infection: An Experimental Study in Rat

Objectives To compare the efficacy of a single prophylactic dose of intra-peritoneal vancomycin and teicoplanin with anti-biotic treated Dacron grafts (vancomycin, teicoplanin, 10 or 40% fusidic acid-soaked grafts) in preventing vascular graft infections in a rat model. Design Prospective, randomized, controlled animal study. Materials and methods The graft infections were established in the subcutaneous tissues of 80 female Sprague–Dawley rats by the implantation of Dacron prostheses followed by the topical inoculation with methicillin-resistant Staphylococcus aureus. The study groups were as follows: (1) uncontaminated control group, (2) untreated contaminated group, (3) contaminated group with intra-peritoneal vancomycin, (4) contaminated group with intra-peritoneal teicoplanin, (5) contaminated group received vancomycin-soaked Dacron graft, (6) contaminated group received teicoplanin-soaked Dacron graft, (7) contaminated group received 40% fusidic acid-soaked Dacron graft, and (8) contaminated group received 10% fusidic acid-soaked Dacron graft prophylaxis. The grafts were removed after 7 days and evaluated by a quantitative culture analysis. Results No infection was detected in controls. The untreated contaminated group had a high bacteria count (6.0×10 4 CFU/cm 2 Dacron graft). Groups that received intra-peritoneal vancomycin or teicoplanin had less bacterial growth (4.8×10 3 and 3.9×10 3 CFU/cm 2 Dacron graft, respectively). Similarly, the group that received 10% fusidic acid-soaked graft showed less bacterial growth (3.6×10 3 CFU/cm 2 Dacron graft). The groups with vancomycin-, teicoplanin- and 40% fusidic acid-soaked grafts showed no evidence of infection. Statistical analyses demonstrated that intra-peritoneal prophylactic antibiotic treatment was less effective in inhibiting bacterial growth than high concentration antimicrobial-soaking of grafts. Conclusion The use of vancomycin-, teicoplanin- and 40% fusidic acid-soaked grafts was effective in preventing primary prosthetic vascular graft infection.

Prostacyclin production from seeded prosthetic vascular grafts.

Endothelial cell seeding has been proposed as a method of improving patency rates in small-calibre prosthetic vascular grafts. In vivo, endothelial cells normally produce prostacyclin (PGI2), a potent antiplatelet agent. The aim of this study was to determine whether seeded grafts show significant PGI2 production after in vivo implantation. Grafts were seeded with either autologous canine venous endothelial cells or autologous microvascular endothelial cells. After 12 weeks, PGI2 production was assessed under basal and stimulated conditions. Seeded grafts were compared with non-seeded controls and the corresponding aorta. The overall patency rate in seeded grafts was 80 per cent compared with 10 per cent in non-seeded grafts (P < 0.01). Grafts seeded with cells from either source produced significantly more PGI2 than unseeded grafts in both basal and stimulated states (P < 0.05). The aorta produced significantly more PGI2 than seeded grafts under both conditions (P < 0.01). Endothelial cell seeding produces a functional graft and leads to an improved patency rate.

Prosthetic vascular graft infection.

The aetiology, diagnosis and management of prosthetic vascular graft infection are reviewed. The importance of contamination at the time of surgery as the crucial aetiological factor is highlighted. Staphylococcus epidermidis is the causative organism in over 50 per cent of cases and the reasons for this are explored. Sound surgical technique, use of prophylactic antibiotics and the avoidance of a groin incision are emphasized as the most important factors in prevention of graft infection. Difficulties of diagnosis are highlighted and the diagnostic role of various imaging methods is assessed. Graft excision with extra-anatomic revascularization is presented as the conventional surgical solution, while the roles of less radical surgical solutions and non-operative management are discussed.

Dental infection in vascular surgical patients.

Seventy patients, 18 women and 52 men of mean age 68 (range 52-81) years, with vascular disease were studied using the Community Periodontal Index of Treatment Needs (CPITN). Twenty-six were edentulous and 44 dentate; 32 dentate patients were wearing partial dentures. All had occlusive peripheral arterial disease (ankle:brachial pressure index less than 0.9) or aortic aneurysm. No significant periodontal pathology was found in edentulous patients. Of the dentate patients, 28 were in the significant pathology range (CPITN 4) and 12 were in the moderate pathology group (CPITN 3); only four had no significant pathology (CPITN 0-2). As a proportion of prosthetic vascular graft infections may be due to dental sepsis, surgeons should consider referral for dental assessment before elective bypass grafting and patients should be warned about the importance of dental care after operation.

The Prophylactic Efficacy of Rifampicin-Soaked Graft in Combination with Systemic Vancomycin in the Prevention of Prosthetic Vascular Graft Infection: An Experimental Study

To investigate the prophylactic efficacy of systemic, topical, or combined antibiotic usage in the prevention of late prosthetic vascular graft infection caused by methicillin-resistant Staphylococcus epidermidis (MRSE) and the differential adherence of S. epidermidis to Dacron and ePTFE grafts in a rat model. Graft infections were established in the back subcutaneous tissue of 120 adult male Wistar rats by implantation of 1-cm(2) Dacron/ePTFE prosthesis followed by topical inoculation with 2 x 10(7) CFU of clinical isolate of MRSE. Each of the series included one group with no graft contamination and no antibiotic prophylaxis (uncontaminated control), one contaminated group that did not receive any antibiotic prophylaxis (untreated control), one contaminated group in which perioperative intraperitoneal prophylaxis with vancomycin (10 mg/kg) was administered, two contaminated groups that received rifampicin-soaked (5 mg/1 ml) or vancomycin-soaked (1 mg/1 ml) grafts, and one contaminated group that received a combination of rifampicin-soaked (5 mg/1 ml) graft with perioperative intraperitoneal vancomycin prophylaxis (10 mg/kg). The grafts were removed sterilely 7 days after implantation and evaluated by using sonication and quantitative blood agar culture. MRSE had significantly greater adherence to Dacron than ePTFE grafts in the untreated contaminated groups (P < 0.001). Rifampicin had better efficacy than vancomycin in topical application, but the difference was not statistically significant (P > 0.05). Intraperitoneal vancomycin showed a significantly higher efficacy than topical vancomycin or rifampicin (P < 0.001). The best results were provided by a combination of intraperitoneal vancomycin in rifampicin-soaked graft groups (P < 0.001). The combination of rifampicin and intraperitoneal vancomycin seems to be the best choice for the prophylaxis of late prosthetic vascular graft infections caused by MRSE.

Prosthetic vascular graft infection: A risk factor analysis using a case–control study

Several factors have been anecdotally reported to increase the risk of prosthetic vascular graft infection (PVGI), a serious complication with high mortality and limb amputation rates. The goal of this study is to confirm purported risk factors using a well-designed statistical model. Patients undergoing vascular graft placement at Mayo Clinic Rochester between January 1, 1982 and December 31, 2002 were retrospectively evaluated, excluding redo cases. PVGI cases had to meet one of the following criteria: perigraft air or fluid >8 weeks postoperatively, positive Gram stain or cultures of graft or perigraft material, intraoperative gross purulence, failure of graft incorporation, or exposed graft. Each case had two controls matched for age, gender and date of surgery. Duration of follow-up for a given control had to be at least equal to the time to infection of the corresponding case. Demographic and other clinical data were collected for each patient. Fifty-one cases and 102 controls met the inclusion criteria. Median age was 68 years. Staphylococcal species were identified in 45% of the total number of cases, and 60% of cases with a recovered organism. Univariate analysis identified groin incision, wound complication and wound infection as significant risk factors for PVGI (p<0.005 for all three factors). After adjusting for age and surgery date, multivariate analysis confirmed the statistical significance of groin incision and wound infection as risk factors for PVGI. This is the first published risk factor analysis that includes statistical evaluation in a case-control study of PVGI. Groin incision, wound complication, and wound infection are significantly associated with developing PVGI. These findings will assist in identifying patients at increased risk of developing subsequent infection. In order to confirm purported risk factors of prosthetic vascular graft infections (PVGI), a well designed case-control study was conducted at Mayo Clinic, Rochester, MN. Univariate and multivariate analyses of 51 cases and 102 controls identified three statistically significant risk factors for the development of PVGI: groin incision, wound complication, and wound infection.

Efficacy of the Direct Thrombin Inhibitor Ximelagatran in Maintaining Small-Diameter Vascular Graft Patency.

Objective: A clinically successful small-diameter prosthetic vascular graft has yet to be developed. Improved performance outcomes are also needed with larger-diameter prosthetic vascular grafts for arterial bypass. Ximelagatran (ExantaTM), a fixed-dose, oral direct thrombin inhibitor, is under investigation for thromboprophylaxis in various clinical settings. We hypothesized that ximelagatran could be successful in promoting patencies of small-diameter prosthetic vascular bypass grafts. We hypothesized that ximelagatran could be successful in promoting patencies of small-diameter prosthetic vascular bypass grafts. This 6-month study compared the performances of grafts implanted in carotid arteries in dogs treated with ximelagatran, aspirin, or ximelagatran + aspirin vs non-treated controls.Methods: Dogs (n=6 per group) received bilateral 6-cm long surgical implants of 4 mm internal diameter standard-walled ePTFE vascular grafts. Grafts were interpolated with end-to-end anastomoses as interposition grafts into the common carotid arteries. Ximelagatran administration (200 mg BID p.o.) began 4 hours post graft-implantation. Aspirin (325 mg QD p.o.) was initiated 3 days pre surgery. Medications were continued until study end point. Vascular graft patencies were assessed by non-invasive ultrasound studies 2 weeks post graft-implantation, then monthly. Study end points were bilateral graft failure or 6 months of implantation, whichever was first. A pathologist performed blinded evaluations of the retrieved grafts through calculations of thrombus-free surface areas (TFSA) and histological analyses of healing.Results: One ximelagatran- and one aspirin-treated dog were excluded from the study owing to surgical complications. Ximelagatran was well tolerated. There were no deviations from canine blood norms other than expected elevated PTs and APTTs in ximelagatran-treated animals. Graft Patency: At 6 months, mean graft patencies were similar for the ximelegatran and the ximelagatran + aspirin groups, but both groups were significantly different compared to the aspirin alone and control groups.1TFSA: Mean TFSA of grafts from both the ximelagatran and ximelagatran + aspirin groups were similar but were significantly different from the aspirin alone group.2Intimal Hyperplasia: Statistical differences between groups were not evident between specific locations. However, grafts from the control and aspirin alone groups had more intimal hyperplasia overall than the ximelagatran and ximelagatran + aspirin groups.Conclusions: Ximelagatran-treated dogs had small-diameter vascular graft implants with higher patencies, greater TFSAs and a trend toward less intimal hyperplasia compared with dogs medicated with aspirin alone or controls. We believe that further investigation is warranted in defining the potential use of ximelagatran in maintaining small-diameter vascular graft patencies.Study GroupDrug Dose(s)Patency*TFSA %1 Month3 Months6 MonthsXimelagatran200 mg BID100% (10/10)100% (10/10)88%1 (7/8)63.4%2Aspirin325 mg QD70% (7/10)40% (4/10)30% (3/10)22.4Ximelagatran + Aspirin200 mg BID + 325 mg QD83% (10/12)66% (8/12)66%1 (8/12)55.0%2Control-17% (2/12)0 (0/12)0 (0/12)0*ratio of number of grafts open to the flow of blood to the total number of evaluable grafts at each time period

Preservation of infected and exposed vascular grafts using vacuum assisted closure without muscle flap coverage

The most widely used techniques for graft preservation after localized graft infections are muscle flap closure or antibacterial dressings and irrigations after débridement. Vacuum assisted closure (VAC) has been increasingly used for complex wounds in vascular surgery, including groin infections, but not directly on exposed bypass grafts as a stand-alone technique. We used the VAC system after wound débridement in four patients with fully exposed synthetic bypass grafts who were too unstable or risky for further operative interventions. Mean duration of VAC use was 22.8 days (range, 6 to 53 days), with time to total wound closure of 30 to 63 days (mean, 41 days). There were no reinfections with 11 to 25 months' follow-up (mean, 18.3 months). For high-risk surgical patients with a fully exposed infected prosthetic vascular graft, VAC therapy along with aggressive débridement and antibiotic therapy may be an effective alternative to current management strategies.

Thrombin‐free Fibrin Coating on Small Caliber Vascular Prostheses Has High Antithrombogenicity in Rabbit Model

Fibrin coatings on prosthetic vascular graft, which are conventionally produced by fibrinogen and thrombin, are expected to improve antithrombogenicity and healing characteristics. Thrombin is one of the factors of blood coagulation cascade; however, it has a possibility to play a negative role in the graft antithrombogenicity. The purpose of this study was to evaluate the performance of our new grafts, thrombin-free fibrin-coated small caliber vascular prostheses. Knitted polyester fabric vascular prostheses 2 mm in internal diameter were coated with fibrin coating with thrombin (Graft I) or without thrombin (Graft II). Both grafts were implanted in bilateral common carotid arteries of 35 Japanese white rabbits, with Graft I in one side and Graft II in the contralateral side. Graft patency, histology, thrombin activity, and platelet deposition were compared between both grafts on postoperative days (PODs) 1, 3, 7, 10, 14, 30, and 60. Both grafts were patent without thrombus or stenosis at each end point (maximal period, POD 60). Macro- and microscopic findings revealed that no obvious difference was observed between both grafts. Before graft implantation, thrombin activities in Grafts I and II were 0.711 +/- 0.086 and 0.009 +/- 0.007 optical density at 405 nm, respectively. Thrombin activity of Graft II was significantly less than that of Graft I in every period after graft implantation, and platelet deposition of Graft II was significantly less than that of Graft I until POD 30. Thrombin-free fibrin-coated vascular prostheses have superior performance of antithrombogenicity to conventional fibrin-coated vascular prostheses with thrombin.

Role of Delayed Tc-99m HMPAO Labeled Leukocyte Scintigraphy In the Diagnosis of Coronary Mycotic Aneurysm

Coronary mycotic aneurysms are rare with a poor prognosis. Atherosclerosis often predisposes to aneurysmal dilatation. In children, Kawasaki disease and in adults trauma, vasculitis, syphilis, dissection, and postcoronary angioplasty contribute to coronary mycotic aneurysms. Radiolabeled leukocytes have been used in the diagnosis of prosthetic valve endocarditis and vascular graft infections. Abnormal accumulation of radiolabeled leukocytes have also been reported in infra renal aortic aneurysms. We present a case of a coronary mycotic aneurysm where delayed Tc-99m HMPAO labeled leukocyte imaging played an important role leading to the diagnosis.

Multicenter Evaluation of the Bovine Mesenteric Vein Bioprostheses for Hemodialysis Access in Patients with an Earlier Failed Prosthetic Graft

The number of patients requiring hemodialysis increases each year, with a large cohort of patients still requiring prosthetic grafts for hemodialysis. All available prosthetic vascular access grafts have predictable failure rates, leading to a large group of patients with multiple failed access grafts. This report evaluates use of mesenteric vein bioprosthesis (MVB) as a conduit for patients who have failed at least one earlier synthetic vascular access graft. Two-hundred seventy-six access grafts were implanted in patients who had at least one earlier failed synthetic graft. Of these grafts, 183 were MVB and 93 were synthetic. Graft histories were obtained from 128 of the 183 patients who received the MVB, representing a nonrandomized historic data set of previously failed grafts as an internal control group (INT). Patency was determined by Kaplan-Meier analysis, and the Cox proportional hazards model was used for multivariate analysis of factors predictive of effect. Primary patency at 12 months was 35.6% MVB versus 28.4% synthetic grafts. At 24 months, secondary patency was 60.3% MVB, 42.9% synthetic, and 18.0% INT (p < 0.0001, log- rank). Complication rates, including dilation, seroma, infection, and thrombosis, were all notably lower for the MVB compared with synthetic grafts by Cox regression (p < 0.001). Intervention rate per patient year was lower in the MVB group (0.97 versus 1.37) compared with synthetic grafts (p = 0.003). MVB provided superior secondary graft patency compared with both historic graft data or newly implanted nonrandomized synthetic implants. A considerable reduction in thrombosis, infection, and interventions was observed with the MVB graft. These results suggest that MVB offers a safe alternative to patients who have a history of failing synthetic access grafts and may represent an option for extending vascular access to this patient population.

Aortic Graft Infections: Treatment With Arterial Allograft

Since its reintroduction by Kieffer in 1991, many authors have used arterial allografts for surgical management of vascular prosthetic graft infection. During a decade, 25 patients with aortic graft infection were treated using in situ revascularization with arterial allograft. There were 23 male and 2 female patients of mean age of 65.7 ± 8.8 years (range, 43–78). Antibiotic therapy was administered for a mean time of 26 ± 5 days (range, 21–45) in the postoperative period. The mean follow-up time was 2.3 ± 3 years (range, 22 days–8.7 years). The mean in-hospital postoperative stay was 29.6 ± 14 days (range, 9–68). An aorto-enteric fistula (AEF) was present in 11 patients (44%), producing gastrointestinal bleeding. The overall mortality rate was 13 of 23 (56.5%) patients. The allograft-related mortality rate was 5 of 23 (22%). The overall allograft-complicated patient rate was 15 of 23 (65%); we observed 18 allograft ruptures in 12 patients and 8 allograft thromboses in 6 patients. The overall amputation rate was 8.7% (2 of 23). Age of the recipient older than 69 years ( P = .02), positive preoperative marked-leukocyte scanning ( P = .04), and persistent postoperative leukocytosis ( P = .03) were significant variables associated with an increased risk of allograft-related complications. The use of arterial allografts for aortic graft infections represents an interesting alternative for the treatment of graft infection. Nevertheless, there are some problems related to the durability of this type of graft, which can still be considered as a “bridge transplant.”

Reconstruction of the common bile duct by a vascular prosthetic graft: an experimental study in pigs

The purpose of the present study was to investigate whether it was possible to use a vascular graft for reconstruction of the common bile duct (CBD) in pigs. Eight pigs, each weighing approximately 60 kg, were used for the experiments. The gallbladder was dissected and the cystic duct and cystic artery were ligated and divided. The CBD was displayed and divided. Then the CBD was reconstructed with a standard walled expanded polytetrafluoroethylene (ePTFE) vascular graft (internal diameter 4 mm) by means of 12 interrupted monofilament glycomer 63 (Biosyn) 4.0 sutures. The ends of the vascular graft were inserted into the CBD and the sutures were placed through the graft and the CBD in such a way that the latter would cover the former. The anastomotic line was covered by fibrin glue. On postoperative day 8, a laparotomy was performed; the pigs were investigated for signs of gall leakage, and cholangiography was performed. Blood samples for the determination of liver parameters were taken before the primary surgery and before the explorative laparotomy. At evaluations on the eighth postoperative day, all animals except one were without signs of bile leakage. One pig had an encapsulated biloma. Another animal had to be operated on day 6 because of illness, and laparotomy showed a perforated gastric ulcer, but no bile leakage. Cholangiography revealed slight intrahepatic dilatation in all animals. Bilirubin and alkaline phosphatase levels were unaffected by the surgery. Reconstruction of the CBD by means of a vascular graft seems to be a safe procedure in the short term in a pig model.

Vascular Graft Thromboses: 99mTc-HMPAO Leukocyte Scintigraphy False Positive Result in Diagnosis of Infection

We describe a case of a 76-year-old male admitted with fever and pain in his left leg. He had an axillobifemoral bypass, 1 year previously physical examination revealed weak peripheral pulses in both legs and a fluid collection in the left groin. A technetium scan showed intense leukocyte uptake in pelvic graft and in the left groin. This was considered diagnostic for infection. On removal of the graft it was found to be thrombosed. Culture of the graft was negative. Thrombosis of vascular prosthetic grafts can give a false positive result with labelled leukocytes. In case of positive uptake in 99mTc-HMPAO labelled leukocyte scintigraphy, thrombosis must be ruled out by means of complementary techniques.