Xavier Berard

Role of hemodynamic forces in the ex vivo arterialization of human saphenous veins.

BACKGROUND Human saphenous vein grafts are one of the salvage bypass conduits when endovascular procedures are not feasible or fail. Understanding the remodeling process that venous grafts undergo during exposure to arterial conditions is crucial to improve their patency, which is often compromised by intimal hyperplasia. The precise role of hemodynamic forces such as shear stress and arterial pressure in this remodeling is not fully characterized. The aim of this study was to determine the involvement of arterial shear stress and pressure on vein wall remodeling and to unravel the underlying molecular mechanisms. METHODS An ex vivo vein support system was modified for chronic (up to 1 week), pulsatile perfusion of human saphenous veins under controlled conditions that permitted the separate control of arterial shear stress and different arterial pressure (7 mm Hg or 70 mm Hg). RESULTS Veins perfused for 7 days under high pressure (70 mm Hg) underwent significant development of a neointima compared with veins exposed to low pressure (7 mm Hg). These structural changes were associated with altered expression of several molecular markers. Exposure to an arterial shear stress under low pressure increased the expression of matrix metalloproteinase (MMP)-2 and MMP-9 and tissue inhibitor of metalloproteinase (TIMP)-1 at the transcript, protein, and activity levels. This increase was enhanced by high pressure, which also increased TIMP-2 protein expression despite decreased levels of the cognate transcript. In contrast, the expression of plasminogen activator inhibitor-1 increased with shear stress but was not modified by pressure. Levels of the venous marker Eph-B4 were decreased under arterial shear stress, and levels of the arterial marker Ephrin-B2 were downregulated under high-pressure conditions. CONCLUSIONS This model is a valuable tool to identify the role of hemodynamic forces and to decipher the molecular mechanisms leading to failure of human saphenous vein grafts. Under ex vivo conditions, arterial perfusion is sufficient to activate the remodeling of human veins, a change that is associated with the loss of specific vein markers. Elevation of pressure generates intimal hyperplasia, even though veins do not acquire arterial markers. CLINICAL RELEVANCE The pathological remodeling of the venous wall, which leads to stenosis and ultimately graft failure, is the main limiting factor of human saphenous vein graft bypass. This remodeling is due to the hemodynamic adaptation of the vein to the arterial environment and cannot be prevented by conventional therapy. To develop a more targeted therapy, a better understanding of the molecular mechanisms involved in intimal hyperplasia is essential, which requires the development of ex vivo models of chronic perfusion of human veins.

Laparoscopic Surgery for Coeliac Artery Compression Syndrome: Current Management and Technical Aspects

OBJECTIVES The study aims to assess the feasibility and midterm outcome of trans-peritoneal laparoscopy for coeliac artery compression syndrome (CACS). DESIGN Retrospective chart review involving four European vascular surgery departments and two surgical teams. MATERIALS AND METHODS charts for patients who underwent laparoscopy for symptomatic CACS between December 2003 and November 2009 were reviewed. Preoperative computed tomography (CT) angiography and postoperative duplex scan and/or CT angiography were performed. RESULTS Eleven consecutive patients (nine women) with a median age of 52 years (interquartile range: 42.5-59 years) underwent trans-peritoneal laparoscopy for CACS. All patients had a history of postprandial abdominal pain; weight loss exceeded 10% of the body mass in eight cases. Preoperative CT angiography revealed coeliac trunk stenosis >70% in all cases. One patient had additional aortitis and inferior mesenteric artery occlusion, while another patient presented with an occluded superior mesenteric artery. Two conversions occurred (one difficult dissection and one aorto-hepatic bypass needed for incomplete release of CACS). The median blood loss was 195 ml (range: 50-900 ml) and median operative time was 80 min (interquartile range: 65-162.5 years). Symptoms improved immediately in 10/11 patients (no residual stenosis) while one remained unchanged despite a residual stenosis treated by a percutaneous angioplasty. Symptoms reappeared in one patient due to coeliac axis occlusion. The mean follow-up period was 35 ± 23 months (range: 12-78 months). CONCLUSION Our study demonstrates that trans-peritoneal laparoscopy for treating median arcuate ligament syndrome is safe and feasible. Additional patients and a longer follow-up are needed for long-term assessment of this laparoscopic technique.

Dialysis: 'catheter last' not 'fistula first' in elderly patients.

New data suggest that arteriovenous fistulas compared with prosthetic grafts may not be a superior predialysis approach to vascular access for haemodialysis in patients aged ≥80 years. However, the use of catheters as the first vascular access was associated with significantly increased mortality in these patients and should be avoided.

Use of the Flixene vascular access graft as an early cannulation solution

OBJECTIVE The primary end points of this study were safety and efficacy of early cannulation of the Flixene graft (Maquet-Atrium Medical, Hudson, NH). Secondary end points were complications and patency. METHODS This is a prospective single-center nonrandomized study. Study data included patient characteristics; history of vascular access; operative technique; interval between implantation and initial cannulation; complications; and patency at 1 month, 3 months, and every 6 months. Patency rates were estimated by the Kaplan-Meier method. RESULTS Between January 2011 and September 2013, a total of 46 Flixene grafts were implanted in 44 patients (27 men) with a mean age of 63 years. The implantation site was the upper arm in 67% of cases, the forearm in 11%, and the thigh in 22%. Seven grafts were never cannulated during the study period. Of the remaining 39 grafts, 32 (82%) were successfully cannulated within the first week after implantation, including 16 (41%) on the first day. The median interval from implantation to initial cannulation was 2 days (interquartile range, 1-3 days). The median follow-up was 223.5 days (interquartile range, 97-600 days). Five hematomas occurred, but only one required surgical revision. Primary assisted and secondary patency rates were 65% and 86%, respectively, at 6 months and 56% and 86%, respectively, at 1 year. CONCLUSIONS This study suggests that cannulation of the Flixene graft within 1 week after implantation is safe and effective. Early cannulation avoids or shortens the need for a temporary catheter. One-year patency rates appeared to be comparable to those achieved with conventional grafts, but long-term follow-up and randomized controlled studies will be needed to confirm this finding.

In-situ revascularisation for secondary aorto-enteric fistulae: the success of silver-coated Dacron is closely linked to a suitable bowel repair.

OBJECTIVES The purpose of this study was to assess short- and mid-term results of in-situ revascularisation (ISR) using silver-coated Dacron prostheses and bowel repair for management of secondary aorto-enteric fistulae (SAEF). DESIGN Single-centre retrospective chart review. MATERIAL AND METHODS This study includes all the patients treated by ISR using silver-coated Dacron for SAEF between 2006 and 2010. Primary end points were mortality and survival rates. Secondary end points were reinfection-free survival and secondary patency rates. RESULTS Eighteen male patients with SAEF with a median age of 64 years were operated by ISR using silver-coated Dacron during the study period without operative death. The 30-day mortality was 22% and the in-hospital mortality rate was 39%. Indeed, during hospitalisation, a duodenal leak was observed in four patients including three who died. Four others patients died due to multi-system organ failure. Median follow-up was 16 months (range 1-66). The survival rate at 12 months was 55%. One duodenal leak was observed leading to death. The reinfection-free survival and the secondary patency rates at 12 months were 60% and 89%, respectively. CONCLUSION In-situ revascularisation with silver-coated Dacron provides acceptable results in terms of mortality. This treatment may be useful for simple vascular reconstruction and allow greater attention to bowel repair that is a determinant in short- and mid-term survival.

Multicentric Retrospective Study of Endovascular Treatment for Restenosis after Open Carotid Surgery

OBJECTIVES To analyse perioperative and midterm outcomes of carotid artery stenting (CAS) for symptomatic >50% and asymptomatic >70% restenosis after open carotid surgery (OCS). DESIGN A multicentric retrospective study. METHODS Outcome measures 30-day death, neurologic and anatomic (thrombosis, restenosis) events. Univariant and multivariant logistic regression analyses were performed to identify predictive factors for neurologic and anatomic events. RESULTS A total of 249 patients with a mean age of 69 years (range, 45-88) were treated for asymptomatic (86%) or symptomatic (14%) restenosis. The 30-day combined operative mortality and stroke morbidity was 2.8% in asymptomatic patients and 2.9% in symptomatic patients. Events during follow-up (mean duration, 29 months) included stroke in four cases, TIA in two, stent thrombosis in four and restenosis in 21. Kaplan-Meier estimates of overall survival, neurologic-event-free survival, anatomic-event-free survival and reintervention-free survival were 95.4%, 94.7%, 96.7% and 99.5%, respectively, at 1 year and 80.3%, 93.8%, 85.1% and 96%, respectively, at 4 years. Multivariant analysis showed that statin use was correlated with a lower risk of anatomic events (odds ratio (OR) = 0.15 (95% confidence interval (CI) 0.03-0.68), p = 0.01) and that bypass was associated with a higher risk of anatomic events than endarterectomy (OR = 5.0 (95% CI 1.6-16.6), p = 0.009). CONCLUSION CAS is a feasible therapeutic alternative to OCS for carotid restenosis with acceptable risks in the perioperative period. Restenosis rate may be higher in patients treated after bypass.

Comparison of the Antimicrobial Properties of Silver Impregnated Vascular Grafts with and without Triclosan

OBJECTIVES The aim was to compare the antimicrobial efficacy of the silver impregnated collagen coated polyester vascular graft (IGS) with an identical graft combining silver and triclosan (IGSy). METHODS This was an in vitro study. A non-antimicrobial collagen polyester vascular graft served as control (IG). The IG, IGS, and IGSy grafts were contaminated separately with inoculates of each of the following micro-organisms: Staphylococcus epidermidis (SE), methicillin resistant Staphylococcus aureus (MRSA), and Escherichia coli producing extended spectrum beta-lactamase (ESBL-EC) or Candida albicans (CA). MRSA, ESBL-EC, and CA were obtained from retrieved infected grafts. The in vitro antimicrobial efficacies of the contaminated grafts were evaluated by time to kill assays over a 24 hour period in accordance with CLSI Guideline M26-A. All assays were repeated six times. Bacterial survival numbers were obtained at 1, 4, 8, and 24 hours using a standard plate count procedure. Bactericidal activity was defined as a 3 log10 reduction factor (logRF). To calculate the overall difference in the mean log10 CFU/mL within 24 hours, a one way ANOVA with a Bonferroni correction was calculated separately for each graft. RESULTS The IG graft showed an increase in the number of viable organisms for the four strains tested. IGSy offered better antimicrobial properties than IGS for both ESBL-EC and MRSA, since only the IGSy graft achieved > 3 logRF and fulfilled the standard criteria for bactericidal activity at 24 hours with 3.78 and 4.08 logRF, respectively. For samples inoculated with SE and CA, both antimicrobial grafts achieved 24 hour bactericidal activity with > 3 logRF. However, for CA the one-way ANOVA analysis demonstrated that the IGSy graft performed differently in terms of speed of antimicrobial action, appearing more active as early as 4 hours following inoculation (p = .007). CONCLUSION In the in vitro conditions, the Synergy vascular graft combining silver with triclosan demonstrated better short-term antimicrobial activity than the silver graft for all micro-organisms tested.

Early cannulation of the Flixene™ arteriovenous graft

Purpose The aim of this review was to search for evidence of the efficiency of early cannulation of the Flixene™ (Maquet-Atrium Medical, Hudson, NH, USA) arteriovenous graft (AVG) in the current literature and to assess its patency and complication rates. Methods Searches in Pubmed, Medline, Embase and the Cochrane Library were performed using the following specific search terms: early cannulation AVG and/or Flixene™ graft. The primary outcomes were mean time to first cannulation and patency rates at 12 months. Secondary outcomes were complications. Results Six studies reporting outcomes in a total of 260 procedures were included in this review. The median delay from intervention to first cannulation was documented in four studies and was less than 3 days. Primary assisted patency at 12 months ranged from 45% to 53% in the four documented series. In five studies, documented secondary patency at 12 months ranged from 63% to 92%. Two studies compared outcomes between traditional and Flixene™ grafts: one study reported significantly (p<0.01) improved one-year patency using the Flixene™ graft, the two studies did not report significant differences in complication rates between both groups. The rate of infection and pseudo-aneurysm formation ranged from 0 to 11% and 0 to 6%, respectively. Conclusions This review shows that early cannulation of the Flixene™ graft within 3 days following its implantation is feasible with one-year patency and complication rates equivalent to those of conventional grafts which can be cannulated only after 2 weeks.

Hemodynamic Conditions may Influence the Oversizing of Stent Grafts and the Postoperative Surveillance of Patients with Ruptured Abdominal Aortic Aneurysm Treated by EVAR.

BACKGROUND To report the causes of second rupture in patients treated with a stent graft for ruptured abdominal aortic aneurysm (rAAA). CASE REPORT A 69-year-old man was admitted for abdominal pain and hypovolemic shock 22 months after endovascular exclusion of an rAAA with an aortomonoiliac stent graft and a crossover bypass despite normal duplex ultrasound and sac shrinkage at 1 year. During emergent laparotomy, a type IA endoleak was discovered and the aortomonoiliac stent graft was explanted. A Dacron bypass was interposed between the infrarenal aorta and the iliac extension stent graft. CONCLUSIONS Considering the literature, this report has 3 implications for the endovascular treatment of rAAA. First, 30% oversizing is preferable to 15% when treating an rAAA assessed by computed tomography angiography (CTA) performed during permissive hypotension. Second, the surveillance program should rely on CTA and not on a duplex examination to detect any endoleaks or migration. Finally, partial stent graft explantation is a valid option for decreasing aortic clamping time.

Laparoscopic Resection of a Middle Colic Artery Aneurysm

We report herein the successful laparoscopic resection of an asymptomatic 3-cm middle colic artery aneurysm in a young woman. Endovascular treatment represents nowadays the first-line option facing visceral artery aneurysm, but in this case, embolization was excluded because of hostile anatomy. Advantages of laparoscopic approach were the safe resection of the aneurysm with immediate evaluation of the bowel tolerance and the possibility of a histological examination of the arterial wall, without the disadvantages of laparotomy.