Computational prediction of proximal sealing in endovascular abdominal aortic aneurysm repair with unfavorable necks.

BACKGROUND AND OBJECTIVE: Endovascular aortic aneurysm repair (EVAR) has become the standard treatment for abdominal aortic aneurysms in most centers. However, proximal sealing complications leading to endoleaks and migrations sometimes occur, particularly in unfavorable aortic anatomies and are strongly dependent on biomechanical interactions between the aortic wall and the endograft. The objective of the present work is to develop and validate a computational patient-specific model that can accurately predict these complications. METHODS: Based on pre-operative CT-scans, we developed finite element models of the aorta of 10 patients who underwent endovascular aortic aneurysm repair, 7 with standard morphologies and 3 with unfavorable anatomies. We simulated the deployment of stent grafts in each aorta by solving mechanical equilibrium with a virtual shell method. Eventually we compared the actual stent ring positions from post-operative computed-tomography-scans with the predicted simulated positions. RESULTS: A successful deployment simulation could be performed for each patient. Relative radial, transverse and longitudinal deviations were 6.3 ± 4.4%, 2.5 ± 0.9 mm and 1.4 ± 1.1 mm, respectively. CONCLUSIONS: The numerical model predicted accurately stent-graft positions in the aortic neck of 10 patients, even in complex anatomies. This shows the potential of computer simulation to anticipate possible proximal endoleak complications before EVAR interventions.

Predictive Numerical Simulations of Double Branch Stent-Graft Deployment in an Aortic Arch Aneurysm.

Total endovascular repair of the aortic arch represents a promising option for patients ineligible to open surgery. Custom-made design of stent-grafts (SG), such as the Terumo Aortic® RelayBranch device (DB), requires complex preoperative measures. Accurate SG deployment is required to avoid intraoperative or postoperative complications, which is extremely challenging in the aortic arch. In that context, our aim is to develop a computational tool able to predict SG deployment in such highly complex situations. A patient-specific case is performed with complete deployment of the DB and its bridging stents in an aneurysmal aortic arch. Deviations of our simulation predictions from actual stent positions are estimated based on post-operative scan and a sensitivity analysis is performed to assess the effects of material parameters. Results show a very good agreement between simulations and post-operative scan, with especially a torsion effect, which is successfully reproduced by our simulation. Relative diameter, transverse and longitudinal deviations are of 3.2 ± 4.0%, 2.6 ± 2.9 mm and 5.2 ± 3.5 mm respectively. Our numerical simulations show their ability to successfully predict the DB deployment in complex anatomy. The results emphasize the potential of computational simulations to assist practitioners in planning and performing complex and secure interventions.

Model reduction methodology for computational simulations of endovascular repair.

Endovascular aneurysm repair (EVAR) is a current alternative treatment for thoracic and abdominal aortic aneurysms, but is still sometimes compromised by possible complications such as device migration or endoleaks. In order to assist clinicians in preventing these complications, finite element analysis (FEA) is a promising tool. However, the strong material and geometrical nonlinearities added to the complex multiple contacts result in costly finite-element models. To reduce this computational cost, we establish here an alternative and systematic methodology to simplify the computational simulations of stent-grafts (SG) based on FEA. The model reduction methodology relies on equivalent shell models with appropriate geometrical and mechanical parameters. It simplifies significantly the contact interactions but still shows very good agreement with a complete reference finite-element model. Finally, the computational time for EVAR simulations is reduced of a factor 6-10. An application is shown for the deployment of a SG during thoracic endovascular repair, showing that the developed methodology is both effective and accurate to determine the final position of the deployed SG inside the aneurysm.

Editor's Choice - Ex vivo Renal Artery Repair with Kidney Autotransplantation for Renal Artery Branch Aneurysms: Long-term Results of Sixty-seven Procedures.

OBJECTIVE/BACKGROUND: To evaluate the long-term outcome of renal revascularization by ex vivo renal artery reconstruction and autotransplantation for renal artery branch aneurysms (RABAs). METHODS: Between 1991 and 2015, 67 ex vivo renal artery reconstructions with kidney autotransplantation were performed in 55 adults (mean age 47 years) and 10 children to repair 87 RABAs. The main underlying disease was fibromuscular dysplasia in 34 patients. Other etiologies were systemic congenital disease in eight patients, spontaneous dissecting aneurysms in five, iatrogenic aneurysms in three, atheromatous aneurysms in two and unknown etiology in 13. Median RABA diameter was 20.5 mm. Fifty-three patients (82%) were hypertensive, 60 had normal renal function and no patient was on hemodialysis. Seven patients (11%) were operated on after failure of an endovascular procedure. The mean number of renal artery branches repaired per patient was 3.5 and multiple aneurysms were treated in 14 patients (22%). The hypogastric artery was used in 41 patients, the saphenous vein in 18, the superficial femoral artery in five and a combination of different materials in three. RESULTS: No deaths occurred during the first 30 days. Primary patency at 30 days was 90.8% following to six early thromboses. Three patients (5%) were lost to follow up. No other thrombosis occurred. At 8 years, the primary and primary-assisted patency were 88% and 91%, respectively. Survival was 95% at 9 years. Among the 53 hypertensive patients, two were lost to follow up. At 9 years, 22 (43%) were cured and nine (18%) were improved with a significant reduction of antihypertensive medication (p < .05). The pre-operative modification of the diet in renal disease (MDRD) clearance was 93 ± 29 mL/minute, the immediate post-operative MDRD was 94 ± 33 mL/minute, and at the end of follow up it was 86 ± 26 mL/minute (p > .05). CONCLUSION: Ex vivo renal artery reconstruction for complex RABAs eliminates the risk of rupture, confers a benefit to hypertension, and preserves renal function with a satisfactory long-term patency.

Common hepatic artery as inflow in kidney transplantation.

Kidney transplantation originating from the hepatic artery has not previously been reported. Herein, we report a third kidney transplantation with the common hepatic artery as inflow. A 62-year-old male with chronic renal failure due to polycystic kidney disease was proposed to a third kidney transplantation. CT-scan showed diffuse calcification of the aorto-iliac axis and the splenic artery. The common hepatic artery was the only artery suitable for anastomosis and as such was chosen as the inflow for retransplantation. The operation was performed through a right subcostal laparotomy. A saphenous bypass was interposed between the common hepatic artery and the graft, then the renal vein was anastomosed to the suprarenal inferior vena cava. Duration of warm ischemia was 27 min. Postoperative course was complicated with delayed graft function of 17 days and pulmonary infection. Patient was discharged at day 30. With a follow-up of 40 months, serum creatinine level and eGFR are, respectively, 191 µmol/L and 32 mL/min. Hepato-renal bypass technique can be used in kidney retransplantation when patient anatomy is not compatible with other classical options.

Early and late results of ex vivo repair and autotransplantation in solitary kidneys.

INTRODUCTION: Autotransplantation of a solitary kidney provides an excellent opportunity to study the immediate and long-term consequences of intra-operative renal ischaemia. The purpose of this report is to describe a series of nine patients who underwent ex vivo repair and autotransplantation on solitary kidneys. PATIENTS AND METHODS: The series included six females and three males with a mean age of 36 years. Seven of the nine patients were hypertensive (mean number of anti-hypertensive agents: 3). Two patients had chronic renal failure (serum creatinine levels: 192 and 205 µmol l(-1)). All arteries except one with Takayasu disease were affected by dysplastic aneurysm or fibrodysplasia lesion. There was no atherosclerotic lesion. The mean number of renal artery branches repaired was 3.1 per patient. Mean duration of ischaemia was 161 min. RESULTS: Creatinaemia increased in all patients following the procedure. Creatinaemia and clearance returned to preoperative values between the 3rd and 10th postoperative days. One kidney was lost due to renal vein thrombosis. Late findings indicated that renal function was stable and there was no deterioration in the function of the autotransplanted kidneys after a follow-up period of 89 months. Preoperative versus postoperative creatinaemia and clearance levels were respectively 111 vs. 105 µmol l(-1) and 66.9 vs. 62.0 ml min(-1) (ns). During the same time, the mean number of anti-hypertensive agents decreased slightly from 3 to 2.5. CONCLUSION: In this small series of patients who underwent ex vivo repair and autotransplantation on solitary kidneys, intra-operative renal ischaemia had no detrimental effect on renal function.

A standardized aortic aneurysm model for the assessment of endovascular stent-graft technology.

Reliable models of aortic aneurysms are required to test endovascular stent-graft technology prior to human use. We describe the creation of a standardized prosthetic aneurysm in an ovine model to assess endovascular technology. In an adult ovine model under general anesthesia, a polyester sphere measuring 6 cm across was sutured onto the infrarenal aorta following aortotomy. Two weeks later an endovascular stent-graft was deployed in the aorta. Exclusion was confirmed on monthly ultrasound duplex and during angiography at three months and under terminal anesthesia at six months. Autopsy along with histology of the specimen were then performed. A total of 10 sheep underwent aneurysm implantation. Nine received a straight tube endovascular stent-graft (Lombard Medical, Abingdon, Oxon, UK) and seven completed the study. Five prosthetic aneurysms shrank during serial imaging with duplex ultrasound and angiography. However, two remained the same size. One of these had a type I endoleak whereas the other had endotension (type I endoleak confirmed at autopsy). This animal model provides a reliable and reproducible method of creating prosthetic aneurysms for assessing endovascular stent-grafts. It was possible to assess aneurysm exclusion non-invasively using duplex ultrasound. Aneurysms effectively excluded from the circulation shrank whereas those with an endoleak did not.

[Carotid endarterectomy: current indications]. / Chirurgie carotide conventionnelle: mise au point des indications.

Indications for carotid endarterectomy have been clarified after the publication of European and North American randomised controlled trials between 1990 and 2004. Recent analysis of pooled data concerning symptomatic carotid stenosis has enhanced the initial results. Surgery in complement to best medical treatment is indicated for stenosis equal or superior to 70% (American calculation of degree of stenosis), especially if the patient is a man, older then 75 years, during the first 2 weeks after the initial neurological event. Benefit of surgery for stenosis between 50 and 69% appears only after 2 years. Surgery is also beneficial for asymptomatic severe stenosis but the precise threshold of carotid stenosis remains unclear. The benefit is lower for women and would be greater in case of stenosis more than 70%, and for patients less than 75 years.

Endovascular repair of abdominal aortic aneurysms in patients with severe angulation of the proximal neck using a flexible stent-graft: European Multicenter Experience.

AIM: The aim of this paper was to report the results of a multicenter study on endovascular repair of abdominal aortic aneurysms (AAA) in patients with important angulation of proximal neck using a flexible stent-graft (Aorfix). METHODS: Endovascular repair of AAA using a flexible stent-graft was performed at 16 centers in 29 patients with angulation of proximal neck greater than 45 degrees. Twenty-three patients (79%) had angulation greater than 60 degrees and were therefore contraindicated for repair with other contemporary devices. RESULTS: Technical success was achieved in all but one case (96%). There was one postoperative death due to multiorgan failure following revision of groin wound for hemorrhage. No patients were converted to open repair. One patient had persisting proximal endoleak despite placement of proximal extension. One patient in whom wireform fractures had been detected died from ruptured aneurysm at nearly 4 year follow-up. CONCLUSION: Endovascular repair using a flexible stent-graft is feasible in patients with highly angulated necks. This stent-graft allows the possibility of a to offer repair for patients un-suitable for the currently available commercial grafts. Mid-term results are acceptable and need to be confirmed by longer follow-up and larger series.

Endovascular treatment of anastomotic false aneurysms of the abdominal aorta.

Conventional surgical treatment of anastomotic false abdominal aortic aneurysms (AFAA) is technically difficult. Morbidity-mortality rates are higher than those for surgery of infrarenal abdominal aortic aneurysm (AAA). Endovascular management without laparotomy or aortic clamping represents an attractive alternative. The purpose of this study was to determine the immediate and middle-term outcome of endovascular management of AFAA. Between 1998 and 2001, 10 patients were treated for AFAA by placement of an endograft. The initial procedure was aortobifemoral bypass for occlusive artery disease in eight cases and resection and grafting for AAA in two cases. Mean age was 70 years. Seven patients were classified ASA 3 or 4. Three patients presented cardiac insufficiency with left ventricular ejection fraction <40%. Eight patients were treated using an aortounilateral iliac artery endograft in association with crossover femorofemoral bypass (3 AneuRx, 2 Endologix, 1 Talent, 1 Zenith, 1 surgeon-made stent). Two patients were treated with an aortoaortic endograft (1 Talent, 1 surgeon-made stent). In two patients extraperitoneal exposure of the common iliac artery was required for introduction of the stent in one case and for surgical closure of the iliac artery in the other case. A total of nine patients underwent another surgical procedure in association with stenting. Four endografts were custom-made. Endograft deployment was successful in all cases. No patient died during the postoperative period. Postoperative computed tomography (CT) scan confirmed exclusion of the aneurysmal sac in all cases. The mean duration of hospitalization was 13 days (range, 5-28 days). During follow-up (mean duration, 17.7 months; range, 5-42 months), one patient died from heart-related causes. No direct or indirect endoleak was detected by CT scan follow-up and a significant reduction in AFAA diameter was noted in the eight patients with follow-up periods lasting 6 months or more. One patient developed occlusion of an aortounilateral iliac artery endograft and was treated by axillobifemoral bypass. In one patient stenosis of the distal end of an aortounilateral iliac endograft was discovered by duplex scan and successfully treated by dilatation. Endovascular treatment of AFAA is technically feasible but requires more complex procedures involving associated surgical procedures and use of custom-made endografts. The morbidity-mortality rate in this small series of high-risk patients was low. Immediate and middleterm exclusion of AFAA was good.

Mortality and morbidity following endovascular repair of abdominal aortic aneurysms: analysis of two single centre experiences.

OBJECTIVE: to show how differences in anatomical and physiological risk factors can affect the outcome of endovascular repair of AAA by describing the experience of two centres with different selection policies. METHODS: one hundred and thirty-five patients (group I) were treated at Queen's Medical Centre (Nottingham, U.K.) using 101 in-house made and 34 manufactured stent-grafts. Median diameter, length and angulation of the proximal aneurysm neck were 26 mm, 27 mm, 40 degrees, respectively. Seventy-six patients had ischaemic heart disease, 47 had left ventricular failure, median forced expiratory volume in one second (FEV1) was 83%, median creatinine was 100 micromol/l and median age was 72 years. Fifty patients (group II) were treated at Timone Hospital (Marseilles, France) using seven in-house made and 43 manufactured stent-grafts. Median diameter, length and angulation of the proximal aneurysm neck were 25 mm, 34 mm, 33 degrees, respectively. Thirteen patients had ischaemic heart disease, two had left ventricular failure, median forced expiratory volume in one second was 101%, median creatinine was 108 micromol/l and mean age was 72 years. RESULTS: anatomical characteristics of the proximal neck were significantly worse in group I (p=0.02 for the three variables). Cardiac comorbidities were more frequent and mean FEV1 was lower in group I (p<0.0001 and p=0.001, respectively. Median aneurysm diameter was significantly greater in group I (65 mm) than in group II (53 mm) (p<0.001). Postoperative mortality was 9% and 0% in groups I and II respectively (p=0.03). The incidence of technical complications (groin wound complications and side branches endoleaks being excluded) was 20% and 0% in groups I and II, respectively (p=0.0006). CONCLUSION: postoperative mortality and technical complication rates were significantly greater in group I than in group II, readily explained by poorer general condition and worse anatomical characteristics of the proximal neck in group I.

Pathophysiology of proximal perigraft endoleak following endovascular repair of abdominal aortic aneurysms: a study using a flow model.

OBJECTIVE: to design a flow model to determine whether and why increased proximal neck angulation correlates with increased risk of proximal perigraft endoleak (PPE) flow. METHODS: a tapered stent-graft (Gianturco stent + Dacron) was deployed with proximal and distal necks made of silicone. The amount of PPE was measured over 30-s periods while the angulation of the proximal neck was increased. RESULTS: PPE flow increased significantly for angulations > or =30 degrees. The graft was lifted off the neck wall and gaps between the stent-graft and the neck created. CONCLUSION: greater neck angulation increased PPE flow. The stent-graft was lifted off the neck and subsequent gaps created. This model could be used to compare available stent-grafts and to test new designs that would improve the seal in angulated necks.

Incidence and treatment of intraoperative technical problems during endovascular repair of complex abdominal aortic aneurysms.

PURPOSE: The purpose of this study was to assess the incidence and management of intraoperative technical problems during endovascular repair (EVR) of complex abdominal aortic aneurysms (AAA). METHODS: From February 1995 to March 1999, 204 EVRs of nonruptured AAA were performed at our institution. One hundred seventy-six patients had an in-house custom-made graft; 172 were aorto-uni-iliac grafts, and four were aortoaortic grafts. Twenty- eight patients had a bifurcated graft. One hundred fourteen patients (56%) were high risk for conventional open repair. One hundred nine patients (53%) were not suitable for most commercially available devices. RESULTS: Intraoperative technical problems occurred in 81 patients (40%). There were 37 endoleaks (27 proximal, 10 distal), 15 graft stenoses, one failure of graft deployment, two graft thromboses, three aortoiliac ruptures, five renal artery occlusions (one bilateral, four unilateral), and 18 internal iliac occlusions (five bilateral, 13 unilateral). Endovascular management of these problems was successful in 37 of the 81 patients (46%) and included 15 balloon dilatations, 21 additional stent placements, and one graft thrombectomy. Fifteen of the 81 patients (19%) had open procedures (four periaortic ligature placements, six open aneurysm repairs, three common iliac ligations, and two extra-anatomic bypass grafts). In the remaining 29 patients, the on-table problem was managed expectantly. During follow-up, two of 37 patients (5%) who were treated successfully with endovascular procedures experienced recurrence. There were five deaths (33%) among the 15 patients who underwent open procedures. CONCLUSION: Intraoperative problems occur frequently during the endovascular management of complex aneurysms. Many of these problems can be managed with additional endovascular techniques without an increased risk of recurrence or procedure-related complications. Open procedures in high-risk patients carry a high mortality rate. The team performing EVR of AAA should be skillful in advanced endovascular and open surgical procedures.

Long-term results of arterial allograft below-knee bypass grafts for limb salvage: a retrospective multicenter study.

PURPOSE: Arterial allografts (AAs) have been recently reconsidered in the treatment of critical limb ischemia when vein material is absent, because of the disappointing results with artificial grafts. The aim of this study was to report the results observed in three centers where AAs were used for infrainguinal reconstruction in limb-threatening ischemia. METHODS: Between 1991 and 1997, 165 AA bypass procedures were performed in 148 patients (male, 90) with a mean age of 70 years (range, 20-93 years). Indications for operation were rest pain in 54 cases and tissue loss in 111 cases. Mean resting ankle pressure was 53 mm Hg in 96 patients who did not have diabetes and mean transcutaneous pressure of oxygen was 10 mm Hg in 52 patients who did have diabetes. In 123 cases (75%), there was at least one previous revascularization on the same limb. AAs were obtained from cadaveric donors. The distal anastomosis was to the below-knee popliteal artery in 34 cases, to a tibial artery in 114 cases, and to a pedal artery in 17 cases. RESULTS: At 30 days, the mortality rate was 3.4%; the primary patency rate was 83.3%; the secondary patency rate was 90%; and the limb salvage rate was 98%. During follow-up (mean, 31 months), 65 grafts failed primarily. Causes of primary failure were thought to be progression of the distal disease in 15 cases, myointimal hyperplasia in 16 cases, graft degradation in 10 cases (four dilations, three stenoses, two ruptures, and one dissection), miscellaneous in eight cases, and not known in 16 cases. Primary patency rates at 1, 3, and 5 years were, respectively, 48.7% +/- 4%, 34.9% +/- 6%, and 16.1% +/- 7%. Secondary patency rates at 1, 3, and 5 years were, respectively, 59. 8% +/- 4%, 42.1% +/- 5%, and 25.9% +/- 8%. Limb salvage rates at 1, 3, and 5 years were, respectively, 83.8% +/- 3%, 76.4% +/- 5%, and 74.2 % +/- 8%. CONCLUSION: AA leads to an acceptable limb salvage rate but poor patency rates. A randomized trial that will compare AAs and polytetrafluoroethylene should be undertaken.

Surgical treatment of extracranial internal carotid artery aneurysms.

PURPOSE: Extracranial internal carotid artery aneurysms (EICAs) can be treated by carotid ligation or surgical reconstruction. In the consideration of the risk of stroke after internal carotid artery (ICA) occlusion, the aim of this study was to report the results of reconstructive surgery for these aneurysms, including lesions located at the base of the skull. METHODS: From 1980 to 1997, 25 ICA reconstructions were performed for EICA: 22 male patients and 3 female patients (mean age, 54.4 years). The cause was atherosclerosis (n = nine patients), dysplasia (n = 12 patients), trauma (n = three patients), and undetermined (n = one patient). The symptoms were focal in 15 cases (12 hemispheric, three ocular), nonfocal in three cases (trouble with balance and visual blurring), and glossopharyngeal nerve compression in one case. Six cases were asymptomatic, including three cases that were diagnosed during surveillance after ICA dissection. In nine cases, the upper limit of the EICA reached the base of the skull. A combined approach with an ear, nose, and throat surgeon allowed exposure and control of the ICA. RESULTS: After operation, there were no deaths, one temporary stroke, two transient ischemic attacks, and 11 cranial nerve palsies (one with sequelae). The ICA was patent on the postoperative angiogram in all but one case. During follow-up (mean, 66 months), there were two deaths (myocardial infarction), one occurrence of focal epileptic seizure at 2 months, and one transient ischemic attack at 2 years. In December 1998, duplex scanning showed patency of the reconstructed ICA in all but one surviving patient. CONCLUSION: Surgical reconstruction is a satisfactory therapeutic choice for EICA, even when located at the base of the skull.

Multiple valve replacement increases the risk of reoperation for structural degeneration of bioprostheses.

BACKGROUND AND AIM OF THE STUDY: The study aim was to analyze the results of reoperations for structural degeneration of bioprostheses, and to define a high-risk population for reoperative procedures. METHODS: A series of 524 consecutive patients who had undergone a first reoperative replacement for a failed bioprosthesis between 1978 and 1998 was reviewed retrospectively. The reoperative procedure comprised 363 single valve replacements, and 161 multiple valve replacements. During the original procedure, 648 bioprostheses had been implanted in the mitral (n = 403), aortic (n = 220) and tricuspid (n = 25) positions. RESULTS: The mean interval between the original procedure and reoperation was 8.8 +/- 3.3 years. Tissue valve failure was revealed by recurrence of cardiac insufficiency in 70% of cases. The overall early mortality rate was 8%, but early mortality rates for elective single mitral and aortic reoperative valve replacements were only 3.9% and 4%, respectively. Early mortality following reoperation for single and multiple valve replacement was 6.0% and 12.4% respectively (p = 0.02). Other significant multivariable predictors for early mortality were old age (p = 0.003), NYHA functional class (p = 0.007), presence of ascites (p = 0.02) and reoperation performed before 1988 (p = 0.013). CONCLUSIONS: The risk of reoperation for structural degeneration of bioprostheses is acceptable for elective single reoperative valve replacement as opposed to multiple reoperative valve replacement. This may limit the use of bioprostheses during the original procedure when multiple valve replacement is required.

[Uretero-arterial fistulas: report of 2 cases and review of the literature]. / Fistules urétéro-artérielles: à propos de 2 cas et revue de la littérature.

Uretero-arterial fistulas are rare. The authors report two new cases complicating iliac vascular surgery. These fistulas occurred in a particular context: aorto-iliac disease, neoplasm and pelvic radiotherapy. Prolonged ureteric catheterisation is a risk factor found in 65% of cases. The clinical diagnosis is difficult and must be suggested in the presence of episodes of haematuria, sometimes minimal and intermittent, but often cataclysmic. The clinical context is highly suggestive of the diagnosis. The most useful complementary investigations are arteriography and retrograde ureteropyelography. Surgical treatment is complex, as it is performed in an emergency context in patients with a poor general state and it must treat both the vascular and the urological problem. Embolization can be proposed in some cases. The prognosis remains serious due to the frequency and severity of postoperative complications, which is why this disease must be investigated in all patients at risk.