Inge Fourneau

Heparin-bonded ePTFE grafts compared with vein grafts in femoropopliteal and femorocrural bypasses: 1- and 2-year results.

OBJECTIVE Many patients with peripheral arterial occlusive disease who require a lower-limb bypass have no available autologous saphenous vein (ASV) for the procedure and thus require a prosthetic graft. Expanded polytetrafluoroethylene (ePTFE) grafts are commonly used, but results with these prostheses have varied, especially when the distal anastomosis is below the knee. However, there is increasing evidence that ePTFE grafts to which heparin has been bound with use of covalent endpoint linkage provide better results. This nonrandomized study compared the performance of these grafts with that of ASV conduits in the largest clinical series of heparin-bonded ePTFE graft implantations reported so far. METHODS The records of 350 patients who underwent a lower-limb bypass procedure that used either a heparin-bonded ePTFE graft (n = 240) or an ASV graft (n = 110) were reviewed, and preoperative, operative, and follow-up data were recorded. Kaplan-Meier analyses were used to calculate primary patency and limb salvage rates in the two graft groups; results were compared by using log-rank testing. RESULTS The primary patency rates at 1 year for the heparin-bonded ePTFE grafts were 92% for above-knee femoropopliteal (AK FP) bypasses, 92% for below-knee femoropopliteal (BK FP) bypasses, and 79% for femorocrural (FC) applications. The corresponding 2-year rates were 83%, 83%, and 69%, respectively. In the ASV group, the 1-year primary patency rates for AK FP, BK FP, and FC bypasses were 91%, 72%, and 69%, respectively; the 2-year rates were 80%, 72%, and 64%, respectively. There were no significant differences in patency when AK FP, BK FP, or FC procedures were considered separately. Two-year limb salvage rates in the heparin-bonded ePTFE graft group were 92%, 98%, and 87%, respectively, for AK FP, BK FP, and FC bypasses; in the ASV group, the rates were 100%, 91%, and 96%, respectively. Two infections occurred in patients given a heparin-bonded ePTFE graft. CONCLUSION In this large retrospective study, heparin-bonded ePTFE grafts had 1- and 2-year primary patency results that were not significantly different from those for ASV grafts. Results in BK FP and FC applications were especially promising. Randomized studies comparing the use of heparin-bonded ePTFE and ASV grafts in the treatment of peripheral arterial disease are needed to substantiate our results.

Treatment of mycotic aneurysms with involvement of the abdominal aorta: single-centre experience in 44 consecutive cases

OBJECTIVE To review our management of mycotic aneurysms involving the abdominal aorta over the past 2 decades to assess the safety and efficacy of in-situ and extra-anatomic repair combined with antibiotic treatment. MATERIALS AND METHODS From March 1990 to August 2008, 44 patients with a mycotic aneurysm involving the abdominal aorta were treated at our University Hospital. For all patients, we recorded the aetiology, clinical findings and anatomic location of the aneurysm, as well as bacteriology results, surgical and antibiotic therapy and morbidity and mortality. RESULTS Twenty-one (47.7%) of the mycotic aneurysms had already ruptured at the time of surgery. Free rupture was present in nine patients (20.5%). Contained rupture was observed in 12 patients (27.3%). Urgent surgery was performed in 18 cases (40.9%). Revascularisation was achieved by in-situ reconstruction in 37 patients (84.1%), while extra-anatomic reconstruction was performed in six patients (13.6%). One patient (2.3%) was treated with a combined in-situ and extra-anatomic reconstruction. In one case (2.3%), endovascular aneurysm repair (EVAR) was performed. In-hospital mortality was 22.7%, 50% in the extra-anatomic reconstruction group and 18.9% in the in-situ repair group. One-third (33.3%) of our patients, who presented with a ruptured mycotic aneurysm died in the peri-operative period. This mortality was 13% in the patient-group presenting with an intact aneurysm. Of the 34 surviving patients, 12 patients (27.3% of surviving patients died after discharge from our hospital. In half of these patients, an acute cardiac event was to blame. Three patients (8%) showed re-infection after in-situ reconstruction. CONCLUSION Management of mycotic aortic aneurysms remains a challenging problem. The results of surgery depend on many factors. In our experience, in-situ repair remains a feasible and safe treatment option for patients who are in good general condition at the time of surgery.

Long-term results after endovascular abdominal aortic aneurysm repair using the Cook Zenith endograft

OBJECTIVE This study assessed the long-term outcome of patients with abdominal aortic and aortoiliac aneurysms treated with the Cook Zenith endovascular graft (Cook Inc, Bloomington, Ind). METHODS Between September 1998 and October 2003, 143 patients underwent elective endovascular aneurysm repair (EVAR) using the Cook Zenith endograft. Data from these patients were reviewed from a prospective database in October 2008. Primary outcome measures were overall survival, intervention-free survival, and freedom from aneurysm rupture. Secondary outcome measures were early and late postoperative complications, including endoleaks. RESULTS Mean follow-up was 66.4 months (range, 1.9-121.0 months). Overall survival was 72.1% at the 5-year follow-up and 50.9% at the 8-year follow-up. Intervention-free survival was 77.1% at 5 years and 63.8% at 8 years. There were no reintervention-related deaths. Six patients had a late aneurysm rupture, which was fatal in three. Freedom from aneurysm rupture was 98.1% at 5 years and 91.0% at 8 years. Late complications occurred throughout the follow-up period, with a tendency for aneurysm rupture and surgical conversion to occur at a later stage in the follow-up period. Aneurysm sac enlargement during follow-up was associated with late aneurysm rupture and with the need for reintervention. CONCLUSION Elective EVAR using the Cook Zenith endograft provides excellent results through a mean follow-up of >5 years. There is a low aneurysm-related mortality and an acceptable rate of postoperative complications and reinterventions. The occurrence of late complications throughout the follow-up period stresses the need for continued postoperative surveillance in EVAR patients.

Human thoracic and abdominal aortic aneurysmal tissues: Damage experiments, statistical analysis and constitutive modeling.

Development of aortic aneurysms includes significant morphological changes within the tissue: collagen content increases, elastin content reduces and smooth muscle cells degenerate. We seek to quantify the impact of these changes on the passive mechanical response of aneurysms in the supra-physiological loading range via mechanical testing and constitutive modeling. We perform uniaxial extension tests on circumferentially and axially oriented strips from five thoracic (65.6 years ± 13.4, mean ± SD) and eight abdominal (63.9 years ± 11.4) aortic fusiform aneurysms to investigate both continuous and discontinuous softening during supra-physiological loading. We determine the significance of the differences between the fitted model parameters: diseased thoracic versus abdominal tissues, and healthy (Weisbecker et al., J. Mech. Behav. Biomed. Mater. 12, 93-106, 2012) versus diseased tissues. We also test correlations among these parameters and age, Body Mass Index (BMI) and preoperative aneurysm diameter, and investigate histological cuts. Tissue response is anisotropic for all tests and the anisotropic pseudo-elastic damage model fits the data well for both primary loading and discontinuous softening which we interpret as damage. We found statistically relevant differences between model parameters fitted to diseased thoracic versus abdominal tissues, as well as between those fitted to healthy versus diseased tissues. Only BMI correlated with fitted model parameters in abdominal aortic aneurysmal tissues.

The learning curve of totally laparoscopic aortobifemoral bypass for occlusive disease. How many cases and how safe

OBJECTIVES Totally laparoscopic aortic surgery is appealing. However, the adoption of this technique in the broad vascular world is hampered by the steep learning curve and the fear of exposing patients to excessive morbidity and mortality. We assessed how many patients should be treated to overcome this learning curve. MATERIALS AND METHODS The first 50 patients treated with totally laparoscopic aortobifemoral bypass for severe aorto-iliac occlusive disease were followed prospectively. Operative variables such as operative time, aortic clamping time, amount of blood loss, conversion to laparotomy etc were recorded (as well as 30-day mortality and morbidity). To discover a turning point we used the technique of sliding averages. These data were compared with the mortality and morbidity as predicted by POSSUM and P-POSSUM. RESULTS A clear turning point, with improved operative variables, was seen after 20-30 patients. Mortality and morbidity were not higher than predicted by POSSUM and P-POSSUM. CONCLUSIONS These data confirm the intuition of most people involved in laparoscopic aortic surgery that the learning curve could be set at 25-30 cases. However, patients are not exposed to excessive morbidity and mortality during this learning curve.

Unstable femoral neck fractures in young adults: treatment with the AO 130-degree blade plate

OBJECTIVE To evaluate the clinical outcome of the treatment of unstable femoral neck fractures using the AO 130-degree blade plate. DESIGN Between 1980 and 1994, thirty-four consecutive patients younger than age fifty years with an unstable intracapsular femoral neck fracture (Garden Types III-IV) were treated with internal fixation. SETTING University Hospital Gasthuisberg, Leuven, Belgium. INTERVENTION The AO 130-degree blade plate with an antirotation, 6.5-millimeter, partially threaded cancellous lag screw was used. RESULTS Nineteen (63.3 percent) patients had an excellent result, seven (23.3 percent) had a good result, three (10 percent) had a fair result, and one (3.3 percent) had a poor result. Delayed union was observed in one case, and avascular necrosis was observed in two cases. Two implants perforated the subchondral bone. CONCLUSION Stable fixation with the AO 130-degree blade plate avoids damage to the adjacent blood supply to the femoral head and appears to guarantee a good final outcome of unstable intracapsular femoral neck fractures in young adults.

A method for incorporating three-dimensional residual stretches/stresses into patient-specific finite element simulations of arteries.

The existence of residual stresses in human arteries has long been shown experimentally. Researchers have also demonstrated that residual stresses have a significant effect on the distribution of physiological stresses within arterial tissues, and hence on their development, e.g., stress-modulated remodeling. Through progress in medical imaging, image analysis and finite element (FE) meshing tools it is now possible to construct in vivo patient-specific geometries and thus to study specific, clinically relevant problems in arterial mechanics via FE simulations. Classical continuum mechanics and FE methods assume that constitutive models and the corresponding simulations start from unloaded, stress-free reference configurations while the boundary-value problem of interest represents a loaded geometry and includes residual stresses. We present a pragmatic methodology to simultaneously account for both (i) the three-dimensional (3-D) residual stress distributions in the arterial tissue layers, and (ii) the equilibrium of the in vivo patient-specific geometry with the known boundary conditions. We base our methodology on analytically determined residual stress distributions (Holzapfel and Ogden, 2010, J. R. Soc. Interface 7, 787-799) and calibrate it using data on residual deformations (Holzapfel et al., 2007, Ann. Biomed. Eng. 35, 530-545). We demonstrate our methodology on three patient-specific FE simulations calibrated using experimental data. All data employed here are generated from human tissues - both the aorta and thrombus, and their respective layers - including the geometries determined from magnetic resonance images, and material properties and 3-D residual stretches determined from mechanical experiments. We study the effect of 3-D residual stresses on the distribution of physiological stresses in the aortic layers (intima, media, adventitia) and the layers of the intraluminal thrombus (luminal, medial, abluminal) by comparing three types of FE simulations: (i) conventional calculations; (ii) calculations accounting only for prestresses; (iii) calculations including both 3-D residual stresses and prestresses. Our results show that including residual stresses in patient-specific simulations of arterial tissues significantly impacts both the global (organ-level) deformations and the stress distributions within the arterial tissue (and its layers). Our method produces circumferential Cauchy stress distributions that are more uniform through the tissue thickness (i.e., smaller stress gradients in the local radial directions) compared to both the conventional and prestressing calculations. Such methods, combined with appropriate experimental data, aim at increasing the accuracy of classical FE analyses for patient-specific studies in computational biomechanics and may lead to increased clinical application of simulation tools.

Endoprosthetic Treatment of a Mycotic Superficial Femoral Artery Aneurysm

Purpose: To describe the successful stent-graft exclusion of a mycotic aneurysm of the superficial femoral artery. Case Report: A 78-year-old man presented with Salmonella arteritis and the formation of a mycotic false aneurysm of the superficial femoral artery. Antibiotics were administered; the aneurysm was excluded using 2 Hemobahn stent-grafts, and the surrounding hematoma was drained. One year postoperatively, there are no clinical or biochemical signs of infection. Ultrasound examination does not show any fluid around the patent stent-graft. Conclusions: Stent-graft placement might be an alternative to traditional surgery in selected cases of mycotic aneurysm.

Extracranial carotid artery stenting in surgically high-risk patients using the Carotid Wallstent endoprosthesis: midterm clinical and ultrasound follow-up results

AbstractThe purpose of this study was to evaluate the feasibility, safety and midterm outcome of elective implantation of the Carotid Wallstent® in patients considered to be at high surgical risk. In a prospective study, 54 carotid artery stenoses in 51 patients were stented over a 24-month period. Three patients underwent bilateral carotid artery stenting. Institutional inclusion criteria for invasive treatment of carotid occlusive disease (carotid endarterectomy or carotid artery stenting) are patients presenting with a 70% or more symptomatic stenosis and those with an 80% or more asymptomatic stenosis having a life-expectancy of more than 1 year. All patients treated by carotid artery stenting were considered at high risk for carotid endarterectomy because of a hostile neck (17 patients—31.5%) or because of severe comorbidities (37 patients—68.5%). No cerebral protection device was used. Of the 54 lesions, 33 (61.1%) were symptomatic and 21 (38.8%) were asymptomatic. Follow-up was performed by physical examination and by duplex ultrasonography at 1 month, 6 months, 1 year and 2 years after the procedure. All 54 lesions could be stented successfully without periprocedural stroke. Advert events during follow-up (mean 13.9 ± 5.7 months) were non-stroke-related death in 6 patients (11.1%), minor stroke in 4 stented hemispheres (7.4%), transient ipsilateral facial pain in 1 patient (1.8%), infection of the stented surgical patch in 1 patient (1.8%) and asymptomatic instent restenosis in 4 patients (7.4%). The percutaneous implantation of the Carotid Wallstent®, even without cerebral protection device, appears to be a safe procedure with acceptable clinical and ultrasonographic follow-up results in patients at high surgical risk. But some late adverse events such as ipsilateral recurrence of non-disabling (minor) stroke or instent restenosis still remain real challenging problems.

Endovascular stent-graft and first rib resection for thoracic outlet syndrome complicated by an aneurysm of the subclavian artery

Abstract Purpose: To report our experience with a combined endovascular and surgical approach for arterial thoracic outlet syndrome (TOS) complicated by an aneurysm of the subclavian artery. Methods: We treated three consecutive patients suffering from arterial thoracic outlet syndrome complicated by an aneurysm of the subclavian artery by the use of a stent-graft and a first rib resection. These patients were reviewed retrospectively. Results: At a mean follow-up of 37.3 months all patients were free of symptoms without late complications. Conclusions: Endovascular stent-grafting followed by decompression of the costoclavicular space is an attractive alternative to the conventional surgical approach of complicated arterial TOS.