Management of Infected Aortic Prosthetic Grafts

Variability of [18F]FDG-PET/LDCT reporting in vascular graft and endograft infection

PURPOSE

18F-fluoro-D-deoxyglucose positron emission tomography with low dose and/or contrast enhanced computed tomography ([18F]FDG-PET/CT) scan reveals high sensitivity for the diagnosis of vascular graft and endograft infection (VGEI), but lower specificity. Reporting [18F]FDG-PET/CT scans of suspected VGEI is challenging, reader dependent, and reporting standards are lacking. The aim of this study was to evaluate variability of [18F]FDG-PET/low dose CT (LDCT) reporting of suspected VGEI using a proposed standard reporting format.

METHODS

A retrospective cohort study was conducted including all patients with a suspected VGEI (according to the MAGIC criteria) without need for urgent surgical treatment who underwent an additional [18F]FDG-PET/LDCT scan between 2006 and 2022 at a tertiary referral centre. All [18F]FDG-PET/LDCT reports were scored following pre-selected criteria that were formulated based on literature and experts in the field. The aim was to investigate the completeness of [18F]FDG-PET/LDCT reports for diagnosing VGEI (proven according to the MAGIC criteria) and to evaluate if incompleteness of reports influenced the diagnostic accuracy.

RESULTS

Hundred-fifty-two patients were included. Median diagnostic interval from the index vascular surgical procedure until [18F]FDG-PET/LDCT scan was 35.5 (7.3-73.3) months. Grafts were in 65.1% located centrally and 34.9% peripherally. Based on the pre-selected reporting criteria, 45.7% of the reports included all items. The least frequently assessed criterion was FDG-uptake pattern (40.6%). Overall, [18F]FDG-PET/LDCT showed a sensitivity of 91%, a specificity of 72%, and an accuracy of 88% when compared to the gold standard (diagnosed VGEI). Lower sensitivity and specificity in reports including ≤ 8 criteria compared to completely evaluated reports were found (83% and 50% vs. 92% and 77%, respectively).

CONCLUSION

Less than half of the [18F]FDG-PET/LDCT reports of suspected VGEI met all pre-selected criteria. Incompleteness of reports led to lower sensitivity and specificity. Implementing a recommendation with specific criteria for VGEI reporting is needed in the VGEI-guideline update. This study provides a first recommendation for a concise and complete [18F]FDG-PET/LDCT report in patients with suspected VGEI.

How to combine CTA, 99mTc-WBC SPECT/CT, and [18F]FDG PET/CT in patients with suspected abdominal vascular endograft infections?

PURPOSE

We aimed at comparing 99mTc-HMPAO white blood cells (99mTc-WBC) scintigraphy, 18fluorine-fluorodeoxyglucose ([18F]FDG) positron emission tomography/computed tomography (PET/CT) and CT angiography (CTA) in patients with suspected abdominal vascular graft or endograft infection (VGEI). Moreover, we attempted to define a new visual score for interpreting [18F]FDG PET/CT scans aiming at increasing its specificity.

METHODS

We prospectively compared 99mTc-WBC SPECT/CT, [18F]FDG PET/CT, and CTA in 26 patients with suspected abdominal VGEI. WBC scans were performed and interpreted according to EANM recommendations. [18F]FDG PET/CT studies were assessed with both qualitative (Sah's scale and new visual score) and semi-quantitative analyses. CTA images were interpreted according to MAGIC criteria. Microbiology, histopathology or a clinical follow-up of at least 24 months were used to achieve final diagnosis.

RESULTS

Eleven out of 26 patients were infected. [18F]FDG PET/CT showed 100% sensitivity and NPV, with both scoring systems, thus representing an efficient tool to rule out the infection. The use of a more detailed scoring system provided statistically higher specificity compared to the previous Sah's scale (p = 0.049). 99mTc-WBC SPECT/CT provided statistically higher specificity and PPV than [18F]FDG PET/CT, regardless the interpretation criteria used and it can be, therefore, used in early post-surgical phases or to confirm or rule out a PET/CT finding.

CONCLUSIONS

After CTA, patients with suspected late VGEI should perform a [18F]FDG PET/CT given its high sensitivity and NPV. However, given its lower specificity, positive results should be confirmed with 99mTc-WBC scintigraphy. The use of a more detailed scoring system reduces the number of 99mTc-WBC scans needed after [18F]FDG PET/CT. Nevertheless, in suspected infections within 4 months from surgery, 99mTc-WBC SPECT/CT should be performed as second exam, due to its high accuracy in differentiating sterile inflammation from infection.

Digestive hemorrhage and fever as a result of a double secondary aortoenteric fistula following the repair of a juxtarenal abdominal aortic aneurysm and an infection of the aortobifemoral bypass graft: a case report

A double secondary aortoenteric fistula (AEF) occurs in a patient who has had significant aortic surgery and is characterized by a direct connection between the gastrointestinal (GI) tract and the aorta at two separate sites.

IMPORTANCE

During aortoc reconstructive surgery, the patient may present with a variety of unusual complaints, including fever and GI bleeding. These symptoms are indicative of problems, including the development of an aortoentric fistula, particularly when there is a double secondary fistula.

CASE PRESENTATION

The patient was admitted to the hospital due to hematemesis, melena, and high-grade fever after undergoing synthetic grafting aortobifemoral bypass (anatomical reconstruction) and partial resection of the juxtarenal abdominal aortic aneurysm. Pus discharge and a double aortoenteric fistula in unusual sites such as the second-third portion of the duodenum and caecum are visible in upper GI endoscopy and computed tomography angiography. The patient underwent a two-stage open surgery, the first stage involving aortic limb graft exclusion and extra anatomical reconstruction, and the second stage involving graft removal, fistula management, and bowel repair. Then the patient spent a few days in the surgical intensive care unit before being discharged.

CLINICAL DISCUSSION

Primary and secondary AEF are the two categories of AEF. In patients who underwent aortic reconstruction surgery, the frequency of secondary AEF ranges from 0.36 to 1.6%. Due to the 8:1 injury ratio in the secondery AEF, men suffer more injuries than women.There are two types of fistula depending on whether or not the suture line is involved. The first form is graft enteric erosion, which excludes the suture line, while the second type is entric graft fistula, where the suture line is included. Most common site fistula is third and fourth part of duodenum and least common site is fistula formation in large bowel.

CONCLUSIONS

An uncommon complication is double secondary AEF following aortic reconstruction surgery. Since one of the most significant presentations an AEF patient can present with is major GI bleeding and sepsis, A delay in seeking immediate medical treatment could result in the patient's death. It should be emphasized that one of the mechanisms for AEF formation and a frequent cause of sepsis in patients is recurrent aortic graft infection following aortic reconstruction surgery.

[18F]FDG Uptake in Non-Infected Endovascular Grafts: A Retrospective Study

Purpose: After endovascular aneurysm repair (EVAR), an increased [¹⁸F]FDG uptake may be observed at PET/CT, being common to both vascular graft/endograft infection (VGEI) and sterile post-surgical inflammation. Increased non-specific metabolic activity, due to foreign body reaction, can persist for several years after surgery, thus complicating the interpretation of PET/CT studies. In this paper, we aimed to assess [¹⁸F]FDG distribution at different time-points after the implant of abdominal Endurant^® endografts in patients without suspicion of infection. Methods: We retrospectively evaluated [¹⁸F]FDG/CT in 16 oncological patients who underwent abdominal aortic aneurysm exclusion with Endurant^® grafts. Patients had no clinical suspicion of infection and were followed up for at least 24 months after scan. [¹⁸F]FDG PET/CT scans were interpreted using both visual and semi-quantitative analyses. Results: The time between the EVAR procedure and [¹⁸F]FDG PET/CT ranged between 1 and 36 months. All grafts showed mild and diffuse [¹⁸F]FDG uptake without a focal pattern. Mean values of SUVmax were 2.63 ± 0.48 (95% CI 2.38-2.88); for SUVmean 1.90 ± 0.33 (95% CI 1.72-2.08); for T/B ratios 1.43 ± 0.41 (95% CI 1.21-1.65). SUVmax and SUVmean were not correlated to the time elapsed from the procedure, but we observed a declining trend in T/B ratio over time. Conclusions: Endovascular implant of Endurant^® grafts does not cause a significant inflammatory reaction. The evidence of faint and diffuse [¹⁸F]FDG uptake along the graft can reliably exclude an infection, even in early post-procedural phases. Therefore, in patients with a low probability of VGEI, [¹⁸F]FDG PET/CT can also be performed immediately after EVAR.

Biodegradable and antithrombogenic chitosan/elastin blended polyurethane electrospun membrane for vascular tissue integration

Current commercialized vascular membranes to treat coronary heart disease (CHD) such as Dacron and expanded polytetrafluoroethylene (ePTFE) have been associated with biodegradable and thrombogenic issues that limit tissue integration. In this study, biodegradable vascular membranes were fabricated in a structure of electrospun nanofibers composed of polyurethane (PU), chitosan (CS) and elastin (0.5%, 1.0%, and 1.5%). The physicochemical properties of the membranes were analyzed, followed by the conduction of several test analyses. The blending of CS and elastin has increased the fiber diameter, pore size and porosity percentage with the appearance of identical chemical groups. The wettability of PU membranes was enhanced up to 39.6%, demonstrating higher degradation following the incorporation of both natural polymers. The PU/CS/elastin electrospun membranes exhibited a controlled release of CS (Higuchi and first-order mechanisms) and elastin (Higuchi and Korsmeyer-Peppas mechanisms). Delayed blood clotting time was observed through both activated partial thromboplastin time (APTT) and partial thromboplastin time (PT) analyses where significantly delay of 26.8% APTT was recorded on the PU membranes blended with CS and elastin, in comparison with the PU membranes, supporting the membrane's antithrombogenic properties. Besides, these membranes produced a minimum of 2.6 ± 0.1 low hemolytic percentage, projecting its hemocompatibility to be used as vascular membrane.

FDG PET/CT in abdominal aortic graft infection: A case report and literature review

This case report follows a 47-year-old man who had multiple grafts undergoing FDG PET/CT (positron emission tomography/computed tomography) scan to evaluate for graft infection. Initial CT showed enhancing soft tissue and fluid collection around the graft, and the subsequent FDG PET/CT showed findings concerning for graft infection. This case exemplifies that FDG PET/CT is a synergistic tool in diagnosing aortic graft infections, a rare and often fatal complication of aortic grafts.

Vascular Graft Infections: An Overview of Novel Treatments Using Nanoparticles and Nanofibers

Vascular disease in elderly patients is a growing health concern, with an estimated prevalence of 15–20% in patients above 70 years old. Current treatment for vascular diseases requires the use of a vascular graft (VG) to revascularize lower or upper extremities, create dialysis access, treat aortic aneurysms, and repair dissection. However, postoperative infection is a major complication associated with the use of these VG, often necessitating several operations to achieve complete or partial graft excision, vascular coverage, and extra-anatomical revascularization. There is also a high risk of morbidity, mortality, and limb loss. Therefore, it is important to develop a method to prevent or reduce the incidence of these infections. Numerous studies have investigated the efficacy of antibiotic- and antiseptic-impregnated grafts. In comparison to these traditional methods of creating antimicrobial grafts, nanotechnology enables researchers to design more efficient VG. Nanofibers and nanoparticles have a greater surface area compared to bulk materials, allowing for more efficient encapsulation of antibiotics and better control over their temporo-spatial release. The disruptive potential of nanofibers and nanoparticles is exceptional, and they could pave the way for a new generation of prosthetic VG. This review aims to discuss how nanotechnology is shaping the future of cardiovascular-related infection management.

Deep Femoral Vein Reconstruction for Abdominal Aortic Graft Infections is Associated with Low Aneurysm Related Mortality and a High Rate of Permanent Discontinuation of Antimicrobial Treatment

OBJECTIVE

Aortic prosthesis infection is a devastating complication of aortic surgery. In situ reconstruction with the neo-aorto-iliac system (NAIS) bypass technique has become increasingly used and is recommended in recent treatment guidelines. The main aim was to evaluate NAIS procedural outcomes when undertaken after previous open or endovascular aortic repair in Sweden.

METHODS

In this retrospective study, The National Quality Registry for Vascular Surgery (Swedvasc) was used to identify Swedish centres that offered the NAIS bypass procedure for aortic prosthesis infection between 2008 and 2018. Variables of special interest were procedural details, short and long term survival, renal and other complications, and the durtion of antimicrobial treatment.

RESULTS

Forty patients (36 males, four females [mean age 69 years], 32 open repairs, seven endovascular aortic repairs [EVAR] and one fenestrated EVAR; 21 presented with aorto-enteric fistula) operated on with NAIS bypass were reviewed. The median time from the primary aortic intervention to the NAIS bypass procedure was 32 months (range 0 - 252 months). Mean ± standard deviation operating time was 645 ± 160 minutes, mean blood loss was 6 277 ± 6 525 mL, mean length of intensive care unit stay was 5.3 ± 3.7 days, and mean length of overall hospital stay was 21.2 ± 11.4 days. Thirty-five patients (88%) had a positive microbial culture; the most commonly isolated pathogen was Candida spp. The majority of patients survived for 30 days (n = 35 [88%]), and 33 (83%) and 32 (80%) patients survived for 90 days and one year, respectively. The number of surviving patients free from antimicrobial treatment at 90 days, six months, and one year was 19 (58%), 29 (88%), and 30 (94%). After a mean long term follow up of 69.9 ± 44.7 months, 20 patients were still alive.

CONCLUSION

The NAIS bypass procedure offered reasonable survival and functional outcomes, and was associated with a high cure rate, defined as freedom from any antimicrobial treatment.

Contemporary Outcomes After Partial Resection of Infected Aortic Grafts

INTRODUCTION

Aortic graft infection remains a considerable clinical challenge, and it is unclear which variables are associated with adverse outcomes among patients undergoing partial resection.

METHODS

A retrospective, multi-institutional study of patients who underwent partial resection of infected aortic grafts from 2002 to 2014 was performed using a standard database. Baseline demographics, comorbidities, operative, and postoperative variables were recorded. The primary outcome was mortality. Descriptive statistics, Kaplan-Meier (KM) survival analysis, and Cox regression analysis were performed.

RESULTS

One hundred fourteen patients at 22 medical centers in 6 countries underwent partial resection of an infected aortic graft. Seventy percent were men with median age 70 years. Ninety-seven percent had a history of open aortic bypass graft: 88 (77%) patients had infected aortobifemoral bypass, 18 (16%) had infected aortobiiliac bypass, and 1 (0.8%) had an infected thoracic graft. Infection was diagnosed at a median 4.3 years post-implant. All patients underwent partial resection followed by either extra-anatomic (47%) or in situ (53%) vascular reconstruction. Median follow-up period was 17 months (IQR 1, 50 months). Thirty-day mortality was 17.5%. The KM-estimated median survival from time of partial resection was 3.6 years. There was no significant survival difference between those undergoing in situ reconstruction or extra-anatomic bypass (P = 0.6). During follow up, 72% of repairs remained patent and 11% of patients underwent major amputation. On univariate Cox regression analysis, Candida infection was associated with increased risk of mortality (HR 2.4; P = 0.01) as well as aortoenteric fistula (HR 1.9, P = 0.03). Resection of a single graft limb only to resection of abdominal (graft main body) infection was associated with decreased risk of mortality (HR 0.57, P = 0.04), as well as those with American Society of Anesthesiologists classification less than 3 (HR 0.35, P = 0.04). Multivariate analysis did not reveal any factors significantly associated with mortality. Persistent early infection was noted in 26% of patients within 30 days postoperatively, and 39% of patients were found to have any post-repair infection during the follow-up period. Two patients (1.8%) were found to have a late reinfection without early persistent postoperative infection. Patients with any post-repair infection were older (67 vs. 60 years, P = 0.01) and less likely to have patent repairs during follow up (59% vs. 32%, P = 0.01). Patients with aortoenteric fistula had a higher rate of any post-repair infection (63% vs. 29%, P < 0.01) CONCLUSION: This large multi-center study suggests that patients who have undergone partial resection of infected aortic grafts may be at high risk of death or post-repair infection, especially older patients with abdominal infection not isolated to a single graft limb, or with Candida infection or aortoenteric fistula. Late reinfection correlated strongly with early persistent postoperative infection, raising concern for occult retained infected graft material.

Surgical treatment of carotid artery stent infection: a case report

The most effective treatment for graft infection is still debated, and the success rate of current treatments is low. We herein report the results of surgical treatment and follow-up of a case of infection acquired during carotid stenting with the aim of exploring the most effective treatments for graft infection. We retrospectively analyzed a patient who was admitted in September 2019. This patient underwent debridement, autologous saphenous vein replacement of the common carotid to internal carotid artery, external carotid artery suturing, and continuous negative-pressure wound therapy for carotid stent infection. Ten days after carotid artery revascularization, the growth of granulation tissue in the incision was good, and we decided to suture the neck incision. Five days after removing the stitches, grade A healing was noted. Furthermore, the carotid artery and autologous vein grafts were unobstructed as shown by carotid artery computed tomography angiography reexamination. The patient was monitored for 8 months with no new neurological symptoms and good healing of the incision. Effective treatment of vascular graft infection includes debridement and removal of the infected graft, autologous vein graft revascularization, and negative-pressure wound therapy combined with antibiotic therapy.

Microbial evolution of vascular graft infections in a tertiary hospital based on positive graft cultures

BACKGROUND

Vascular graft infections are a serious complication in vascular surgery. Correct antibiotic therapy targeted to the most likely infecting species is essential to treat these patients, although the bacterial epidemiology and pathogenesis are still not completely understood. We analyzed the behavior of vascular graft infections and the microbiologic patterns of resistance.

METHODS

A 10-year (2008-2018), single-center, retrospective cohort study was performed of all patients admitted with vascular graft infection identified by positive direct graft cultures. An extensive microbiologic study was performed to analyze the bacterial strains, antibiotic resistance and sensitivity, and prevalence stratified by the year.

RESULTS

A total of 72 vascular graft infections with positive graft cultures occurring in 65 patients were found. Their mean age was 67 ± 9.6 years, and 85% were men. Infection-related mortality was 11%. Of the 65 patients, 14 had undergone aortobifemoral bypass, 13 axillofemoral bypass, 5 femorofemoral bypass, 27 femoropopliteal bypass, and 4 femoral endarterectomy with synthetic patch angioplasty. The median interval from the index procedure to infection was longer for intracavitary than for extracavitary grafts (P = .011). Of the 72 infections, 48 were monomicrobial and 24 were polymicrobial. Gram-negative bacteria were predominantly identified in intracavitary graft infections (54%). In contrast, gram-positive bacteria were most frequent in the extracavitary graft group (58%). Multidrug-resistant bacterial species occurred more frequently in early graft infections (P = .002). Throughout the study duration, an overall decrease in gram-positive infections and an increase in gram-negative infections was observed, especially in extensively drug-resistant strains. A similar progression was found in all nosocomial infections.

CONCLUSIONS

The present study has shown that vascular graft infection microbiology changed in accordance with graft location and interval to infection from revascularization surgery and had also evolved over the study period with patterns similar to those for all nosocomial infections. This highlights the importance of studying the specific microbiology of each healthcare center and its relationship to vascular graft infections to achieve the best treatment possible.

Treatment of prosthetic vascular graft infection in the groin with ultrasound debridement: A case report

Introduction

Prosthetic graft infection (PGI) is associated with low patient survival rates. The effectiveness of ultrasound debridement in chronic wound healing has been previously reported; however, data on the use of ultrasound technology and its effect on the treatment of PGI are still lacking. We report a case in which PGI in the groin was managed by graft removal using ultrasound debridement.

Presentation of case

A 70-year-old man was diagnosed with chronic limb-threatening ischemia and underwent a femoral-femoral bypass with a polytetrafluoroethylene graft. Eight months postoperatively, he developed an infection at the femoral incision site. Graft removal was performed using ultrasound debridement. The estimated blood loss was 10 mL. The wound healed, and the patient has remained in good health for 2 years postoperatively.

Discussion

When the ultrasonic probe is applied to the wound, ultrasonic energy penetrates into the tissue, and a fibrinolytic action removes necrotic or infected tissue without removing healthy tissue, thereby minimizing bleeding. Using this technique, we were able to perform effective debridement at not only the wound but also the anastomosis.

Conclusion

It is our opinion that this technique can be used to achieve adequate debridement with little bleeding during graft removal and may provide a new option for the treatment of PGI.

Mid-Term Results of Endovascular Aneurysm Sealing in the Treatment of Abdominal Aortic Aneurysm With Unfavorable Morphology

PURPOSE

To report mid-term results of endovascular aneurysm sealing (EVAS) of abdominal aortic aneurysms (AAA) deemed unsuitable for a standard endovascular aneurysm repair (EVAR).

METHODS

A prospectively maintained database of 42 patients with EVAR-unfavorable anatomy treated by EVAS combined with chimney grafts in case of the proximal AAA neck shorter than 5 mm was analyzed. Early outcomes included final angiographic result, intra- and early post-operative deaths, and complications. Mid-term outcomes included all-cause mortality (ACM), aneurysm-related mortality (ARM), patency of the stents, occurrence of endoleaks, serious complications and graft failures defined as the AAA growth of more than 5 mm, type I endoleak, occlusion of the stent-graft or chimney graft, aorto-duodenal fistula, or aneurysm rupture.

RESULTS

The procedure was completed in all patients. Twenty-eight chimney grafts were implanted in 19 patients. Patients were followed for a median of 24 months (range 12-34 months). There were 2 intraoperative ruptures and 1 patient died in an early postoperative period. The cumulative ACM was 15, 21, and 36% at 12, 24, and 36 months, respectively, and the cumulative ARM was 8, 11, and 27% at 12, 24, and 36 months, respectively. Three out of 5 aneurysm-related deaths were due to a secondary aorto-duodenal fistula. The cumulative incidence of graft failure was 20, 27, and 42% at 12, 24, and 36 months, respectively. The cumulative incidence of an endoleak was 5, 9, and 23% at 12, 24, and 36 months, respectively. The graft failure increased significantly both ACM (p = .012) and ARM (p = .00003). The implantation of chimney grafts at the initial procedure increased ARM significantly (p = .008). The presence of an endoleak did not have any significant influence on ACM and ARM.

CONCLUSION

Patients treated with EVAS for AAAs with EVAR-unfavorable anatomy, especially those with chimney grafts, exhibit a high risk of graft failure and subsequent death.

Do Surgical Site Infections in Open Aortoiliac Surgery Differ Between Occlusive and Aneurysmal Arterial Disease?

Background:

Surgical site infections (SSI) are frequently seen after aortoiliac vascular surgery (2%-14%). Deep SSIs are associated with graft infection, sepsis, and mortality. This study evaluates the difference in incidence and nature of SSI following open aortoiliac surgery for aneurysmal disease compared to occlusive arterial disease.

Methods:

A retrospective cohort study was conducted, including all consecutive patients who underwent open aortoiliac vascular surgery between January 2005 and December 2016 in the Amphia Hospital, Breda, the Netherlands. Patients were grouped by disease type, either aneurysmal or occlusive arterial disease. Data were gathered, including patient characteristics, potential risk factors, and development of SSI. Surgical site infections were defined in accordance with the criteria of the Centers for Disease Control.

Results:

Between January 2005 and December 2016, a total of 756 patients underwent open aortoiliac surgery of which 517 had aortoiliac aneurysms and 225 had aortoiliac occlusive disease. The group with occlusive disease was younger, predominantly male, and had more smokers. After exclusion of 228 patients undergoing acute surgery, the SSI rate after elective surgery was 6.2%, with 10 of 301 SSIs in the aneurysmal group (3.0%) and 22 of 213 SSIs in the group with occlusive disease (10.3%, P < .001). Also, infection-related readmission and reintervention were higher after occlusive surgery, 6.6% versus 0.9% ( P < .001) and 4.2% versus 0.9% ( P = .003), respectively. Staphylococcus aureus was found as the most common pathogen, causing 64% of SSI in occlusive disease versus 10% in aneurysmal disease ( P = .005). Logistic regression showed occlusive arterial disease and chronic renal disease were associated with SSI.

Conclusion:

Our study presents evidence for a higher rate of SSI in patients with aortoiliac occlusive disease compared to aortoiliac aneurysmal disease, in part due to inherent use of inguinal incision in patients with occlusive disease. All precautions to prevent SSI should be taken in patients undergoing vascular surgery for arterial occlusive disease.

Genuine impact of 18F-fluorodeoxyglucose positron emission tomography with contrast-enhanced computed tomography in clinching the diagnosis and follow-up response assessment of vascular graft infections

Vascular graft infection (VGI) is a rare and severe complication after vascular surgery associated with significant morbidity and mortality, but the diagnosis is not always straightforward due to its variable and nonspecific clinical signs. Computed tomography (CT) scan is considered to be the diagnostic tool of choice for advanced VGI, but there is a high incidence of false-negative results, especially in low-grade infections. ¹⁸F-Fluorodeoxyglucose positron emission tomography with contrast-enhanced CT (¹⁸F-FDG PET-CT) imaging can serve as an effective alternative tool for assessment of suspected VGI and also provide accurate anatomic localization of the infective focus. Here, we describe three cases of VGI with various clinical presentations where the site of infection was diagnosed, confirmed, and documented with the help of ¹⁸F-FDG PET-CT imaging.

Current challenges and future trends in manufacturing small diameter artificial vascular grafts in bioreactors

Cardiovascular diseases are a leading cause of death. Vascular surgery is mainly used to solve this problem. However, the generation of a functional and suitable substitute for small diameter (< 6 mm) displacement is challengeable. Moreover, synthetic prostheses, made of polyethylene terephthalate and extended polytetrafluoroethylene show have shown insufficient performance. Therefore, the challenges dominating the use of autografts have prevented their efficient use. Tissue engineering is highlighted in regenerative medicine perhaps in aiming to address the issue of end-stage organ failure. While organs and complex tissues require the vascular supply to support the graft survival and render the bioartificial organ role, vascular tissue engineering has shown to be a hopeful method for cell implantation by the production of tissues in vitro. Bioreactors are a salient point in vascular tissue engineering due to the capability for reproducible and controlled variations showing a new horizon in blood vessel substitution. This review strives to display the overview of current concepts in the development of small-diameter by using bioreactors. In this work, we show a critical look at different factors for developing small-diameter and give suggestions for future studies.

Branched Endovascular Aortic Plug in Patients With Infrarenal Aortic Graft Infection and Hostile Anatomy

Purpose: To present a novel 4-branched endovascular aortic plug (BEVAP) for treatment of patients with infrarenal aortic graft infection. Case Reports: Two polymorbid male patients with aortic graft infections and an unsuturable diseased paravisceral aorta were treated under compassionate use with a custom-made stent-graft. The BEVAP is a factory-modified Zenith t-Branch thoracoabdominal endovascular graft with the distal tubular main graft portion removed, creating an aortic plug that excludes the abdominal aorta while maintaining perfusion to the visceral organs. The BEVAP device is deployed using a femoral approach, and the branches are accessed through an axillary approach. A standard axillobifemoral bypass is created to perfuse the lower body. One to 2 days later, the infected infrarenal graft is resected without the need of aortic clamping or closure of the aortic stump. The BEVAP device in these 2 cases resulted in thrombosis of the abdominal aorta and the infected graft prior to explantation. Conclusion: Using the BEVAP enables radical treatment of selected patients with hostile anatomy and infrarenal aortic graft infections who have an aneurysmal paravisceral aortic segment that prevents traditional radical surgical treatment with in situ reconstruction or extra-anatomical bypass.

Psoas abscess associated with aortic endograft infection caused by bacteremia of Listeria monocytogenes: A case report and literature review (CARE Complaint)

RATIONALE

Endograft infection following endovascular stent for aortic aneurysm is rare (0.6%-3%), but it results in high mortality rate of 25% to 88%.

PATIENT CONCERNS

A 66-year-old hypertensive man underwent an endovascular stent graft for abdominal aortic aneurysm 18 months ago. Recurrent episodes of fever, chills, and abdominal fullness occurred 6 months ago before this admission. Laboratory data showed 20 mg/dL of C-reactive protein and abdominal computed tomography (CT) revealed an aortic endoleak at an urban hospital, so 4-day course of intravenous (IV) amoxicillin/clavulanic acid was given and he was discharged after fever subsided. He was admitted to our hospital due to fever, chills, and watery diarrhea for 1 day. Abdominal CT showed left psoas abscess associated with endograft infection. Blood culture grew Listeria monocytogenes.

DIAGNOSIS

Left psoas abscess associated with endograft infection caused by bacteremia of Listeria monocytogenes.

INTERVENTIONS

IV ampicillin with 8 days of synergistic gentamicin was prescribed and it created satisfactory response. Ampicillin was continued for 30 days and then shifted to IV co-trimoxazole for 12 days.

OUTCOMES

He remained asymptomatic with a decline of CRP to 0.36 mg/dL and ESR to 39 mm/h. He was discharged on the 44th hospital day. Orally SMX/TMP was prescribed for 13.5 months.

LESSONS

Only few cases of aortic endograft infection caused by Listeria monocytogenes had been reported. In selected cases, particularly with smoldering presentations and high operative risk, endograft retention with a prolonged antimicrobial therapy seem plausible as an initial therapeutic option, complemented with percutaneous drainage or surgical debridement if necessary.

Perspective: options in managing aortic graft infections

Thoracic aortic graft infections are infrequent, but are associated with high mortality and morbidity risk. To prevent these life-threatening infections, one must be aware of pathogenesis. When it occurs, a multidisciplinary (surgeon, radiologist, microbiologist, nuclear specialist, infectiologist, anesthesiologist, intensive care specialist) cascade must be initiated. A fast and accurate diagnosis using diagnostic criteria is vital. The appropriate treatment consists of a combination of antibiotics and surgery. Whether or not the vascular prosthesis is preserved depends on a case-by-case basis (tailor-made). Several graft preservation strategies have proven their effectiveness.

Endovascular Aneurysm Repair Complicated with Type Ia Endoleak and Presumable Infection Treated with a Fenestrated Endograft

An 81-year-old patient presented to the emergency room 5 years after infrarenal endovascular aneurysm repair, with a Type Ia endoleak and a presumable infection of the graft material with Listeria monocytogenes . He was treated with a custom-made fenestrated endograft to seal the endoleak and lifelong antibiotic therapy to suppress the infection. Full explantation of graft material is not always preferable, and endovascular treatment combined with antibiotic suppressive therapy is in some cases an appropriate alternative.

Lateral femoral bypass for prosthetic arterial graft infections in the groin

OBJECTIVE

Prosthetic arterial graft infections (PAGIs) in the groin pose significant challenges in terms of revascularization options and risk of limb loss as well as associated morbidities. Although obturator canal bypass (OCB) has been suggested for revascularization of the extremity in these cases, moderate success rates and technical challenges have limited widespread use. Our study analyzed lateral femoral bypass (LFB) as an alternative approach for the treatment of groin PAGIs.

METHODS

This is a retrospective review of a prospectively maintained database of patients who underwent LFB for groin PAGIs at a single center from 2000 to 2017. Patients' data including demographics, comorbidities, perioperative complications, graft patency, and need for reintervention were used. Patients were observed after LFB with duplex ultrasound surveillance in an accredited noninvasive vascular laboratory every 3 months during the first year, followed by every 6 months for the second year and yearly thereafter. After isolation of the infected wound with sterile dressings, remote proximal and distal arterial exposure incisions were made. LFBs were tunneled under the inguinal ligament and lateral to the infected wound from an uninvolved inflow artery or bypass graft to an uninvolved outflow vessel.

RESULTS

A total of 19 LFBs were performed in 16 patients (mean age, 69 ± 12.6 years). Three LFBs were performed urgently for acute bleeding. Choice of conduit included 6 (31.6%) autogenous vein grafts, 10 (52.6%) cadaveric grafts, 2 (10.5%) rifampin-soaked Dacron grafts, and 1 (5.3%) polytetrafluoroethylene graft. Average follow-up was 33 months (range, 0-103 months). Major adverse events occurring within 30 days of the operation included one (5.3%) death and one (5.3%) graft excision for pseudoaneurysm. Primary patency and primary assisted patency at 12 and 24 months were 73% and 83%, respectively. One patient required an amputation 17 months after surgery after failure of repeated revascularization attempts. Overall limb salvage was 93.8% during this follow-up period.

CONCLUSIONS

In this series, LFB for management of groin PAGIs demonstrated higher patency and limb salvage rates compared with previous reports of OCB. Diligent postoperative duplex ultrasound surveillance is critical to the achievement of limb salvage and maintenance of graft patency. These results suggest that LFB, which is technically less complex than OCB, should be considered the first choice for revascularization in select cases of PAGIs involving the groin.

Development and characterisation of a large diameter decellularised vascular allograft

The aims of this study were to develop a biological large diameter vascular graft by decellularisation of native human aorta to remove the immunogenic cells whilst retaining the essential biomechanical, and biochemical properties for the ultimate benefit of patients with infected synthetic grafts. Donor aortas (n = 6) were subjected to an adaptation of a propriety decellularisation process to remove the cells and acellularity assessed by histological analysis and extraction and quantification of total DNA. The biocompatibility of the acellular aortas was determined using standard contact cytotoxicity tests. Collagen and denatured collagen content of aortas was determined and immunohistochemistry was used to determine the presence of specific extracellular matrix proteins. Donor aortas (n = 6) were divided into two, with one half subject to decellularisation and the other half retained as native tissue. The native and decellularised aorta sections were then subject to uniaxial tensile testing to failure [axial and circumferential directions] and suture retention testing. The data was compared using a paired t-test. Histological evaluation showed an absence of cells in the treated aortas and retention of histoarchitecture including elastin content. The decellularised aortas had less than 15 ng mg-1 total DNA per dry weight (mean 94% reduction) and were biocompatible as determined by in vitro contact cytotoxicity tests. There were no gross changes in the histoarchitecture [elastin and collagen matrix] of the acellular aortas compared to native controls. The decellularisation process also reduced calcium deposits within the tissue. The uniaxial tensile and suture retention testing revealed no significant differences in the material properties (p > 0.05) of decellularised aorta. The decellularisation procedure resulted in minimal changes to the biological and biomechanical properties of the donor aortas. Acellular donor aorta has excellent potential for use as a large diameter vascular graft.

Determining the Diagnostic Value of 18F-Fluorodeoxyglucose Positron Emission/Computed Tomography in Detecting Prosthetic Aortic Graft Infection

BACKGROUND

To determine the diagnostic value of 18F-fluorodeoxyglucose positron emission/computed tomography (FDG PET/CT) in detecting prosthetic aortic graft infection (AGI).

METHODS

Twenty-one patients with prosthetic grafts for abdominal aortic aneurysms underwent FDG PET/CT scans for suspected graft infection over a 15-month period. Images were evaluated for tracer pattern and grade of FDG uptake in addition to measuring the maximal standardized uptake value (SUVmax). Two independent nuclear medicine physicians retrospectively evaluated all imaging. The images from a control group of patients with aortic grafts who underwent FDG PET/CT scans for onco-hematological indications were evaluated to establish radiological characteristics of asymptomatic grafts. Secondary parameters that are associated with graft infection such as components of the peripheral blood count were collected. Graft infection status was determined using microbiological outcomes following graft explantation or radiological drainage of perigraft collections and correlated with results of the FDG PET/CT scans to determine infective status.

RESULTS

In the control group, the pattern of FDG uptake was homogenous and diffuse. The mean SUVmax was 3.5 (±1.3). Thirteen out of 21 grafts were confirmed as infected. Tracer uptake in infected grafts displayed an intense and focal pattern, with a median grade of uptake of 4 vs. 2 on a validated 4 point grading scale. The area under the receiver operating curve for FDG PET/CT in detecting infection was 0.85 (±0.15) P = 0.01. Sensitivity was 92%, specificity 63%, and positive and negative predictive values of 80% and 83%, respectively. The SUVmax was significantly higher in infected than noninfected grafts, (10.3 ± 4.2 vs. 5.4 ± 3.4) P = 0.02. According to the receiver operating characteristic analysis, SUVmax greater than 6.3 represented the optimal cutoff between infective and noninfective outcome. Of the secondary parameters collected, grade of uptake and SUVmax were the only significant predictors of infection (odds ratio 2.5, 1.5 respectively) P = 0.05. White cell count, erythrocyte sedimentation rate, and C-reactive protein demonstrated nonsignificant odds ratios of 1.4, 0.9, and 1.0, respectively.

CONCLUSIONS

FDG PET/CT is a valuable diagnostic test for identifying AGI. Infected grafts display significantly greater FDG uptake in a distinctive intense focal perigraft pattern and distribution. SUVmax greater than 6.3 is a good cutoff to determine infective status.

Complex treatment of vascular prostheses infections

Infections after vascular reconstructions are very rare; however, when they occur, they are associated with a high risk of morbidity. In order to obtain the best results possible, the treatment needs to be initiated as early as possible, from the very first signs of infection, and it needs to be carried out in centers specializing in vascular surgery. The aim of the present study was to assess the incidence of infections in a single university center.This retrospective analysis over a 2-year period is based on the medical reports of hospitalized patients who were diagnosed with infection following revascularization.From 2013 to 2014, a number of 151 open reconstructive surgical procedures were performed. 15 patients suffered from infection (10%) of the vascular reconstruction. Of these patients, 40% have had an aorto-bifemoral bypass, 53%-a femoro-popliteal bypass, and 7% (n = 1)-an axillo-femoral bypass. According to the Samson classification, the patients were categorized as follows: group 2: 6 cases, group 3: 2 cases, group 4: 4 cases, and group 5: 3 cases. The most frequent bacteria found were methicillin-resistant Staphylococcus aureus (MRSA) (n = 6, 40%), followed by S aureus (n = 5, 33%). The treatment options were: application of antibiotics alone without any invasive treatment in 3 patients, local irrigation and debridement in 6 patients, complete explantation of the prosthesis with a new extra-anatomic bypass in 6 cases, and partial excision of the prosthesis, which was replaced and covered with muscle flap, in 3 cases. The amputation rate in our study was 18%, which corresponds to the rates published in the literature.The treatment of infections in vascular surgery needs to be complex and adapted to each individual patient, because infections being in a permanent dynamic state. The treatment needs to be performed in specialized centers that have large experience in vascular surgery, in order for the patient to have the best chances of survival and protection from amputation.

Electrospun vascular scaffold for cellularized small diameter blood vessels: A preclinical large animal study

The strategy of vascular tissue engineering is to create a vascular substitute by combining autologous vascular cells with a tubular-shaped biodegradable scaffold. We have previously developed a novel electrospun bilayered vascular scaffold that provides proper biological and biomechanical properties as well as structural configuration. In this study, we investigated the clinical feasibility of a cellularized vascular scaffold in a preclinical large animal model. We fabricated the cellularized vascular construct with autologous endothelial progenitor cell (EPC)-derived endothelial cells (ECs) and smooth muscle cells (SMCs) followed by a pulsatile bioreactor preconditioning. This fully cellularized vascular construct was tested in a sheep carotid arterial interposition model. After preconditioning, confluent and mature EC and SMC layers in the scaffold were achieved. The cellularized constructs sustained the structural integrity with a high degree of graft patency without eliciting an inflammatory response over the course of the 6-month period in sheep. Moreover, the matured EC coverage on the lumen and a thick smooth muscle layer were formed at 6months after transplantation. We demonstrated that electrospun bilayered vascular scaffolds in conjunction with autologous vascular cells may be a clinically applicable alternative to traditional prosthetic vascular graft substitutes.

STATEMENT OF SIGNIFICANCE

This study demonstrates the utility of tissue engineering to provide platform technologies for rehabilitation of patients recovering from severe, devastating cardiovascular diseases. The long-term goal is to provide alternatives to vascular grafting using bioengineered blood vessels derived from an autologous cell source with a functionalized vascular scaffold. This novel bilayered vascular construct for engineering blood vessels is designed to offer "off-the-shelf" availability for clinical translation.

Production and hemocompatibility assessment of novel electrospun polyurethane nanofibers loaded with dietary virgin coconut oil for vascular graft applications

To develop biodegradable polymer scaffolds suitable for vascular tissue engineering applications, the bioengineering community has invested an extensive effort. The most common cause for the failure of vascular graft scaffolds is thrombosis. In this work, the scaffold based on polyurethane and virgin coconut oil was produced by electrospinning process for vascular tissue engineering applications with improved antithrombogenicity. The diameter of this electrospun polyurethane/virgin coconut oil composite was found to be reduced in the range of 886 ± 207 nm compared to pristine polyurethane which was in the range of 969 ± 217 nm. The Fourier transform infrared spectroscopy analysis revealed the interaction between polyurethane and virgin coconut oil as indicated by phase shifting of CH bond along with the formation of hydrogen bond. The contact angle measurement of fabricated composites was found to be increased owing to hydrophobic nature and also exhibited enhanced thermal stability as noted in thermogravimetric analysis. The atomic force microscopy analysis insinuated the increased surface roughness of the composite in comparison with the pure polyurethane. Developed scaffold resulted in delayed blood clotting as revealed by activated partial thromboplastin time and partial thromboplastin time assay. The hemolytic index of fabricated composites was found to be low indicating the enhanced safety of red blood cells. Hence, the newly developed nanofibrous composite scaffold could open the door for a suitable alternative for vascular graft applications.

Systemic thioridazine in combination with dicloxacillin against early aortic graft infections caused by Staphylococcus aureus in a porcine model: In vivo results do not reproduce the in vitro synergistic activity

Introduction

Conservative treatment solutions against aortic prosthetic vascular graft infection (APVGI) for inoperable patients are limited. The combination of antibiotics with antibacterial helper compounds, such as the neuroleptic drug thioridazine (TDZ), should be explored.

Aim

To investigate the efficacy of conservative systemic treatment with dicloxacillin (DCX) in combination with TDZ (DCX+TDZ), compared to DCX alone, against early APVGI caused by methicillin-sensitive Staphylococcus aureus (MSSA) in a porcine model.

Methods

The synergism of DCX+TDZ against MSSA was initially assessed in vitro by viability assay. Thereafter, thirty-two pigs had polyester grafts implanted in the infrarenal aorta, followed by inoculation with 10⁶ CFU of MSSA, and were randomly administered oral systemic treatment with either 1) DCX or 2) DCX+TDZ. Treatment was initiated one week postoperatively and continued for a further 21 days. Weight, temperature, and blood samples were collected at predefined intervals. By termination, bacterial quantities from the graft surface, graft material, and perigraft tissue were obtained.

Results

Despite in vitro synergism, the porcine experiment revealed no statistical differences for bacteriological endpoints between the two treatment groups, and none of the treatments eradicated the APVGI. Accordingly, the mixed model analyses of weight, temperature, and blood samples revealed no statistical differences.

Conclusion

Conservative systemic treatment with DCX+TDZ did not reproduce in vitro results against APVGI caused by MSSA in this porcine model. However, unexpected severe adverse effects related to the planned dose of TDZ required a considerable reduction to the administered dose of TDZ, which may have compromised the results.

Beyond conventional antibiotics - New directions for combination products to combat biofilm

Medical device related infections are a significant and growing source of morbidity and mortality. Biofilm formation is a common feature of medical device infections that is not effectively prevented or treated by systemic antibiotics. Antimicrobial medical device combination products provide a pathway for local delivery of antimicrobial therapeutics with the ability to achieve high local concentrations while minimizing systemic side effects. In this review, we present considerations for the design of local antimicrobial delivery systems, which can be facilitated by modeling local pharmacokinetics in the context of the target device application. In addition to the need for local delivery, a critical barrier to progress in the field is the need to incorporate agents effective against biofilm. This article aims to review key properties of antimicrobial peptides that make them well suited to meet the demands of the next generation of antimicrobial medical devices, including broad spectrum activity, rapid and biocidal mechanisms of action, and efficacy against biofilm.

The Usefulness of Biosynthetic Vascular Graft Omniflow II and Autologous Veins for the Treatment of Massive Infection of Dacron Vascular Graft with Enterococcus faecalis HLAR

Infections of vascular grafts are the most severe complications in vascular surgery. We present the case of a 73-year-old male with infection of a dacron prosthesis with a strain of Enterococcus faecalis. The patient was treated with replacement of a full prosthesis with a combined graft constructed from Biosynthetic Vascular graft Omniflow and autologous veins. This graft is recommended for implantation in patients with a higher risk of infection. Our case is one of the first reported usage of this kind of graft in the aortic region and in a 2 years observation period no recurrence of infection was observed.

Type IIIb Endoleak Associated With an Infected Thoracoabdominal Endograft

We present a 63-year-old male patient who presented with vague abdominal pain after an endoluminal thoracoabdominal aneurysm repair. He was found to have an infected endograft and an associated type IIIb endoleak. We believe that the infection contributed to the fabric degradation along the endograft and resulted in an expanding endoleak. Graft explantation was not performed because of the patient's multiple comorbidities, and the endoleak was treated with an additional stent graft and suppressive antibiotics. Endograft infection may lead to endograft degradation and associated leak. Therefore, an infectious etiology, although rare, should be considered when evaluating a delayed type IIIb endoleak.

Thoracic Aortic Graft Infections Secondary to Propionibacterium Species: Two Cases and Review of the Literature

Aortic graft infections are a rare occurrence, most commonly secondary to gram-positive organisms (Staphylococcus and Streptococcus species). We present 2 cases of thoracic aortic graft infections secondary to anaerobic bacteria, Propionibacterium species. The first case, a 40-year-old male, was found to have an anastomotic aneurysm at the distal anastomosis of a previous thoracoabdominal aneurysm repair. During the open repair of his anastomotic aneurysm, the original graft was not incorporated and cultures later speciated Propionibacterium acnes The second case is a 44-year-old male with a history of abdominal aortic coarctation that was repaired with a thoracic aorta to aortic bifurcation graft as a child who presented with flank pain and was found on imaging to have fluid around his bypass graft. His operating room (OR) cultures also grew out Propionibacterium species. Both patients were treated with graft excision, revascularization, and long-term antibiotics. Anaerobic bacteria are a rare cause of aortic graft infections. Upon review of the literature, these are the first 2 cases of thoracic aortic graft infections secondary to Propionibacterium species. The cultures for both patients took almost a week to speciate, highlighting the importance of following cultures long term. Anaerobic bacteria should be recognized as a cause of latent graft infections.

Outcomes of Aortic Surgery for Abdominal Aortic Graft Infections

Background:

Literature on postoperative outcomes following aortic surgery for aortic graft infection (AGI) is limited by relatively small sample sizes, resulting in lack of national benchmarks for quality of care. We report in-hospital outcomes following abdominal aortic surgery for AGI and identify factors associated with postoperative complications using the Nationwide Inpatient Sample (NIS) database.

Methods:

Patients who underwent aortic graft resection for AGI were identified from the 2002 to 2008 NIS database, a multicenter database capturing 20% of all US admissions. Multivariable logistic regression analyses were performed.

Results:

Among 394 patients (men: 73.4%) who underwent abdominal aortic surgery for AGI, 53% of the admissions were emergent/urgent. A significant trend for decreasing number of abdominal aortic surgery for AGIs per year was observed (Pearson r correlation: −.96; P = .0006). Over the same time span, a significant correlation was also seen with decrease in open and increase in endovascular aortic aneurysm repairs in the NIS database. In-hospital rates of overall postoperative morbidity and mortality were 68.3% and 19.8%, respectively. In-hospital rates of postoperative respiratory failure, renal failure, and cardiac arrest were 35.5%, 14.2%, and 8.9%, respectively. Median length of stay was 26 days, with median hospital charges being US$184 162. On multivariable analysis, increase in age per year (odds ratio [OR] 1.07; 95% confidence interval [CI]: 1.03-1.12) was independently associated with postoperative morbidity, while higher hospital volume for this procedure was protective (OR: 0.71; 95% CI: 0.56-0.89). No preoperative factors were independently associated with postoperative mortality.

Conclusion:

Incidence of abdominal aortic surgery for AGI has progressively declined over the span of our study in association with decreased open and increased endovascular aortic aneurysm repairs. Aortic surgery for AGI is associated with very high morbidity and mortality rates along with prolonged lengths of stay and elevated hospital charges. The outcomes of operations for AGI are better in younger patients and higher volume hospitals.

Management of infected vascular grafts

Infections of vascular grafts are associated with significant mortality and morbidity risk and cost an estimated $640 million annually in the United States. Clinical presentation varies by time elapsed from implantation and by surgical site. A thorough history and physical examination in conjunction with a variety of imaging modalities is often essential to diagnosis. For infected aortic grafts, there are several options for treatment, including graft excision with extra-anatomic bypass, in situ reconstruction, or reconstruction with the neo-aortoiliac system. The management of infected endovascular aortic grafts is similar. For infected peripheral bypasses, graft preservation techniques can be utilized, but in cases where it is not possible, graft removal and revascularization through uninfected tissue planes is necessary. Infected dialysis access can be surgically treated by complete or subtotal graft excision. Diagnosis, general management, and surgical approaches to infected vascular grafts are discussed in this review.

Stent graft infection secondary to appendicitis: an unusual complication of endovascular abdominal aortic aneurysm repair

We present a case of a 73-year-old gentleman with an aortic endograft infection post endovascular abdominal aneurysm repair (EVAR), from whence erosion has come in from an acutely inflamed appendix. To our best understanding, there is no similar case published in the literature. Intra-operatively, there was obvious inflammation and oedema over the retroperitoneal tissue, with frank pus and thrombotic material projecting from the aorta. The tip of an obviously inflamed appendix had stuck to and eroded through the aortic sac, seeding the infection. The endograft was explanted and the aneurysm sac oversewn. Lower limb circulation was preserved with a right axillo-femoral Dacron bypass graft. This case highlights a rare complication following EVAR, and for one to consider unusual sources of graft infection.

18F-Fluorodeoxyglucose positron emission tomography/CT scanning in diagnosing vascular prosthetic graft infection

Vascular prosthetic graft infection (VPGI) is a severe complication after vascular surgery. CT-scan is considered the diagnostic tool of choice in advanced VPGI. The incidence of a false-negative result using CT is relatively high, especially in the presence of low-grade infections. ¹⁸F-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET) scanning has been suggested as an alternative for the diagnosis and assessment of infectious processes. Hybrid ¹⁸F-FDG PET/CT has established the role of ¹⁸F-FDG PET for the assessment of suspected VPGI, providing accurate anatomic localization of the site of infection. However, there are no clear guidelines for the interpretation of the uptake patterns of ¹⁸F-FDG as clinical tool for VPGI. Based on the available literature it is suggested that a linear, diffuse, and homogeneous uptake should not be regarded as an infection whereas focal or heterogeneous uptake with a projection over the vessel on CT is highly suggestive of infection. Nevertheless, ¹⁸F-FDG PET and ¹⁸F-FDG PET/CT can play an important role in the detection of VPGI and monitoring response to treatment. However an accurate uptake and pattern recognition is warranted and cut-off uptake values and patterns need to be standardized before considering the technique to be the new standard.