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.

Outcome and safety of Aorfix™ stent graft in highly angulated necks - a prospective observational study (arbiter 2).

OBJECTIVES: Severe neck angulation is associated with poor outcome following endovascular aneurysm repair. The aim was to study the safety and early outcome of patients with infrarenal aortic aneurysms with severe neck angulation (60-90°) treated with the Aorfix™ endovascular stent graft. DESIGN/METHODS: This was a non-randomized prospective observational study of 30 patients with infra-renal abdominal aortic aneurysms with highly angulated necks. Outcomes were primary technical success, 30 day and short term (30 days-6 months) clinical success and other patient morbidity at 30 days. RESULTS: Median neck angulation was 81.2°. Initial technical success was 93.3% (n = 28) with 2 stents deployed too low. Intra-operatively 3 patients initially had type I endoleaks, but all were resolved by ballooning. 30 day clinical success was 96.7%: there were no type I or type III endoleaks observed, and no reports of graft thrombosis or migration. Early clinical failure was accounted for by one perioperative death (3% mortality). No aneurysm-related interventions were required during follow-up. At 6 months two patients were reported as having type I endoleaks, although both sacs have reduced in size. Neither has required intervention. No patient has died due to aneurysm rupture or required removal of the endograft. CONCLUSION: The results of this study support the continued application of the Aorfix™ graft to the highly angulated neck.

Behcet's Disease : report of a case and review of the literature.

Behcet's disease (BD) is an autoimmune disease of unknown aetiology with multisystem involvement presenting with relapsing orogenital ulcers and uveitis, involvement of central nervous system, joints, lungs, gastrointestinal tract and major blood vessels leading to myriads of presentations, which requires a multidisciplinary approach for satisfactory outcome. We describe a patient with BD, highlight its pathophysiology and management aspects, and present review of pertinent literature.

Early results of a flexible bifurcated endovascular stent-graft (Aorfix).

AIM: First generation stent-grafts were associated with low applicability, high conversion rates due to technical failure and low durability. Second generation stent-grafts need to address these problems in order to secure endovascular aneurysm repair (EVAR) as a viable option to open repair in patients with abdominal aortic aneurysms (AAA). The early results of a second-generation stent-graft (Aorfix) for the treatment of AAA are reported. METHODS: A European multi-centre study of the Aorfix bifurcated endovascular stent-graft was performed. The Aorfix stent-grafts were inserted according to a predefined clinical protocol in 4 centres experienced in EVAR and all data was collected prospectively on a central database. RESULTS: A total of 24 patients underwent attempted aneurysm repair with the Aorfix stent-graft. There were no conversions to open repair. One technical failure resulted in insertion of another stent-graft. At 30-day follow-up there had been no secondary endovascular or open interventions. There were only 2 endoleaks, both of which were type II. CONCLUSIONS: Aorfix currently offers early results, which are at least as good as other second-generation stent-grafts. It has given satisfactory results with highly angulated proximal necks and may improve the treatment outlook for these patients. Whether the unique design features increase durability and reduce long-term complications remains to be seen.

Endovascular repair of ruptured abdominal aortic aneurysm--a challenge to open repair? Results of a single centre experience in 20 patients.

INTRODUCTION: The mortality from ruptured abdominal aortic aneurysm (AAA) remains in the region of 50% despite advances in critical care. Endovascular repair of AAA has been shown to be associated with reduced physiological stress in the elective setting. It is hypothesised that the reduced physiological stress associated with EVAR may improve the outcome in patients with ruptured AAA. METHODS: A feasibility study of endovascular repair of ruptured AAA was undertaken at the University Hospital, Nottingham, U.K. between 1994 and 2000. Patients admitted with ruptured AAA were assessed by a team familiar with endovascular techniques for elective repair of AAA. After giving informed consent patients underwent spiral computed tomographic angiography (CTA) in the majority of cases. Patients were then transferred to the operating theatre for EVAR. RESULTS: Twenty patients underwent repair of ruptured AAA. Of these 20 patients, seven were referred from another hospital. Eight patients were considered unfit for open repair. The median duration of procedure was 180 min (range 120-480) and median blood loss was 1200 ml (range 750-2000 ml). The overall peri-operative mortality was 45%. A number of intra-operative and peri-operative procedures (both open and endovascular) were required to ensure aneurysm exclusion and to deal with the complications of endovascular surgery. CONCLUSIONS: Ruptured AAA remains a particularly hazardous condition to treat. There are a number of advantages of EVAR in this condition. A number of the problems early in the experience of EVAR have been addressed, but further experience is required to demonstrate its efficacy when compared with open repair.

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.

Intrarenal color duplex examination of aortic endograft patients with suprarenal stents.

PURPOSE: To report an experience using intrarenal color duplex ultrasonography (ICDU) to detect high-grade renal artery stenosis in patients who had endovascular repair of abdominal aortic aneurysm (AAA) with suprarenal stent fixation. METHODS: Twenty-eight patients (25 men; mean age 71 years, range 58-83) who had endovascular AAA repair with suprarenal stenting at least 3 months prior to commencement of this study were screened with ICDU. Acceleration time (AT), peak systolic velocity (PSV), end diastolic velocity (EDV), and resistive index (RI) were measured. The Doppler waveform was quantitatively scored on a scale from 0 to 4. AT >0.07 seconds, RI <0.45, or a Doppler waveform score of 0 or 1 (indicating loss of early systolic peak) were indicative of high-grade renal artery stenosis. RESULTS: Median follow-up was 15.5 months (range 3-34). ICDU was successful in 54 (98%) of 55 kidneys scanned. No AT values exceeded 0.07 seconds, all RIs were >0.45, and no waveforms had loss of early systolic peak, indicating that no patient had evidence of high-grade renal artery stenosis. CONCLUSIONS: ICDU is a simple and affordable method that seems well suited to periodic screening in patients with suprarenal stents. Longer follow-up with a larger number of patients is needed before definite conclusions can be drawn about the effect of suprarenal stenting on renal circulation.

Endovascular repair of perisplanchnic abdominal aortic aneurysm with visceral vessel transposition.

PURPOSE: To report a combined endoluminal and open surgical approach for a suprarenal abdominal aortic aneurysm (AAA) with coexistent splanchnic vessel stenoses. METHODS AND RESULTS: A 64-year-old man presented with an aneurysm of the proximal abdominal aorta and severe stenoses of the celiac axis and superior mesenteric artery (SMA). An initial 2-stage plan to stent the visceral vessel stenoses and exclude the aneurysm with a fenestrated stent-graft failed when the celiac lesion could not be crossed. The approach was changed to restore visceral perfusion with a bifurcated left iliosplenic and ilio-SMA bypass graft. Exclusion of the aneurysm was achieved with a custom-made suprarenal aortic tube stent-graft (Ivancev-Malmö) system. The patient is free of symptoms at 22 months, and there was no aneurysm visible on the 14-month CT scan. CONCLUSIONS: Hybrid techniques are an alternative treatment for complex perivisceral aortic aneurysms when total endovascular reconstruction is not possible.

Using the Boazul cuff to reduce blood loss in varicose vein surgery.

OBJECTIVE: this study was designed to assess if the use of a sterile exsanguination tourniquet (Boazul cuff) reduced blood loss from the groin and avulsion wounds during varicose vein surgery, (saphenofemoral disconnection, stripping to knee and multiple avulsions). DESIGN: prospective, parallel cohort study. MATERIALS: thirty-eight patients undergoing primary varicose vein surgery. METHODS: the blood loss and number of avulsion wounds were recorded for each patient. RESULTS: the tourniquet was used on 21 legs and there were 24 legs in the non-tourniquet group. In the tourniquet group, the median blood loss from the groin was 15 ml, (range 5-70 ml), and from the leg was 5 ml, (range 0-120 ml). The corresponding figures for the group without the tourniquet were a median of 17.5 ml, (range 5-105 ml), and a median of 95 ml, (range 10-505 ml). The mean number of avulsions in the tourniquet group was 25 (range 9-38), and in the non-tourniquet group was 15, (range 5-40). There was significantly less blood loss from the leg in the tourniquet group (p<0.0001) despite the fact that there were more avulsions in the tourniquet group (p<0.001). CONCLUSIONS: use of the Boazul cuff significantly decreases the blood loss from the avulsion sites during routine varicose vein surgery, and may encourage the surgeon to perform more avulsions.

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.

Sigmoid ischemia and the inflammatory response following endovascular abdominal aortic aneurysm repair.

PURPOSE: To assess the relationship between sigmoid colonic perfusion, endotoxemia, and cytokine generation in patients undergoing elective open repair (OR) or endovascular repair (EVR) of infrarenal abdominal aortic aneurysms (AAA). METHODS: Ten patients (9 males; average age 67.6 +/- 2.5 years, mean aneurysm diameter 6.9 +/- 0.6 cm) undergoing OR were compared to 10 patients (all males; average age 70.3 +/- 2.6 years, mean aneurysm diameter 6.5 +/- 0.5 cm) whose repair was performed using the EVR technique. The partial pressure of the carbon dioxide gap (PCO2gap = tissue PCO2 - arterial PCO2) of the sigmoid colonic mucosa was measured using a silicone tonometer to evaluate bowel perfusion. Blood samples were collected into pyrogen-free heparinized tubes for quantification of plasma concentrations of endotoxin, tumor necrosis factor alpha (TNF-alpha), and interleukin 6 (IL-6) before, during, and after aortic repair. RESULTS: Patients in the OR group had a significantly greater increase in PCO2gap, suggesting a greater degree of bowel ischemia compared to the EVR group. This was associated with significantly greater postoperative concentrations of endotoxin, TNF-alpha, and IL-6 in the OR group. A significant correlation was found between PCO2gap, IL-6, and postoperative core temperature. CONCLUSIONS: The results suggest that the degree of bowel ischemia, endotoxemia, and cytokine generation following elective infrarenal AAA reconstruction may be reduced if the endovascular technique is used instead of conventional surgery.

Anatomical risk factors for proximal perigraft endoleak and graft migration following endovascular repair of abdominal aortic aneurysms.

INTRODUCTION: proximal perigraft endoleak (PPE) and graft migration are associated with significant morbidity and mortality. Objective data establishing correlation between neck anatomy and these complications are lacking. The aim of this study was to analyse the anatomy of the neck in order to find which variables were significantly associated with PPE and graft migration. METHODS: one hundred and eighty-four patients underwent endovascular repair (EVR) of infrarenal AAA using an in-house custom-made stent graft (Gianturco stents plus Dacron). Thirty-one patients had PPE and fifteen had graft migration. Neck diameter was measured at the level of renal arteries and lower limit of the neck. Necks were classified according to shape. Neck angulation was measured from spiral computed tomography (CT) or magnetic resonance imaging (MRI) reconstructions, or angiograms. Thrombus or atheroma lining and presence of calcifications were recorded. RESULTS: neck angulation was significantly greater in patients who had PPE (50+/-16, p=0. 0005) or graft migration (54+/-20, p=0.003), compared to patients who had none of these two complications (37+/-18). Neck diameter was significantly greater in patients with PPE (p=0.05). Incidence of PPE or graft migration was not significantly higher in the presence of a conical shape, thrombus or atheroma lining and calcifications. CONCLUSION: neck angulation was the risk factor most significantly related to PPE and graft migration.

Mortality rates following endovascular repair of abdominal aortic aneurysms.

PURPOSE: To present the perioperative and late mortality following endovascular repair (EVR) of abdominal aortic aneurysms (AAAs). METHODS: Data were collected prospectively on 221 patients undergoing AAA EVR over a 4-year period (median 5-month follow-up). Patients were classified preoperatively as high risk with at least 1 of these features: serum creatinine > 150 micromol/L, ischemic heart disease or poor left ventricular function, respiratory function < 50% of predicted normal, ruptured or symptomatic AAA, contraindication to or failed open repair, and age > 80 years. RESULTS: One hundred forty (63.3%) patients were classified as high risk, the most common criterion being cardiac disease (n = 96, 68.6%). There were 25 (11.3%) deaths in the 30-day perioperative period, 22 (15.7%) in the high-risk group compared to 3 (3.7%) in the acceptable-risk group (p = 0.02). The most common causes of perioperative death were multisystem organ failure and myocardial infarction. A further 21 (9.5%) late deaths occurred, 16 (11.4%) in the high-risk group and 5 (6.2%) in the acceptable-risk group (p > 0.1). CONCLUSIONS: The mortality of patients at acceptable risk undergoing EVR compares with the best published series for conventional open AAA repair. The perioperative and late mortality in the high-risk patients are substantially higher.

Vascular surgical society of great britain and ireland: changes in proximal aortic neck dimensions following endovascular repair of abdominal aortic aneurysm

BACKGROUND: Dilatation of the proximal neck following conventional open repair of abdominal aortic aneurysm (AAA) has been reported. Such continued dilatation following endovascular repair (EVR) could potentially be a disaster resulting in graft slippage, endoleak and aneurysm rupture. The aim of this study was to detect any change in proximal neck diameter following EVR of AAAs. METHODS: One hundred patients had undergone EVR of an AAA over a 4-year period in whom contrast-enhanced spiral computed tomography was performed both before and after EVR (1 week, 3, 6 and 12 months and annually thereafter). Change in aortic proximal neck diameter, change in maximum aortic diameter, presence of endoleaks, and change in length from the lowest renal artery to the aortic bifurcation was sought. RESULTS: The median anteroposterior and transverse diameter decreased from 64 mm before operation to 56 and 54 mm respectively after operation. This trend in reduction in maximum diameter was not seen in patients with endoleaks. There was no significant change in proximal neck diameter when measured at 5-mm intervals following EVR. There was also no significant change in the aortic length following EVR. CONCLUSION: There was no evidence of proximal neck dilatation or aneurysm length reduction following EVR of AAAs.

Vascular surgical society of great britain and ireland: perioperative renal function following endovascular repair of abdominal aortic aneurysm with suprarenal and infrarenal stents

BACKGROUND: Endovascular repair (EVR) of abdominal aortic aneurysm (AAA) is feasible for selected patients. Placing an uncovered stent across the origins of the renal arteries may improve fixation and seal of the proximal end of the stent-graft. However, this has potential for problems (e.g. renal artery stenosis or microembolization). This study aimed to evaluate the short-term effect of a suprarenal stent on the function of the individual kidney. METHODS: In 30 patients undergoing EVR for AAA, renal function was assessed before and after operation by 99mTc-radiolabelled diethylenetriamine penta-acetate radionuclide renography and daily measurement of serum creatinine levels. Eleven patients had infrarenal stent-grafts using an aorta uni-iliac system (group 1); 19 patients had the device with an uncovered suprarenal stent (modified Gianturco Z stent), ten of which were aorta uni-iliac and nine bifurcated systems (group 2). Individual kidney function was expressed as the whole kidney transit time (WKTT). In addition, glomerular filtration rate (GFR) was measured from serial blood samples following renography. RESULTS: [Table: see text] CONCLUSION: No result reached statistical significance. Placing an uncovered stent over the origins of the renal arteries does not appear to impair kidney function in the short term.

Vascular surgical society of great britain and ireland: prevention of lumbar artery endoleaks following endovascular abdominal aortic aneurysm repair with the selective use of absorbable gelatin sponge

BACKGROUND: The aim of endovascular repair of an abdominal aortic aneurysm is to exclude the aneurysm from the systemic circulation in order to prevent aneurysm expansion and rupture. Lumbar artery (LA) endoleaks have been associated with continued expansion of the aneurysm sac and occur with a reported incidence of approximately 10 per cent. The aim of this study was to reduce the incidence of LA or inferior mesenteric artery (IMA) endoleaks. METHODS: Following deployment of an aortic uni-iliac graft an aneurysmograph was performed by injecting contrast into the aneurysm sac to look for patent aortic side branches. Patients with no visible side branches had an occluder deployed in the contralateral iliac artery. Patients with patent side branches had an absorbable gelatin sponge inserted into the aneurysm sac before occluder deployment. Patients had contrast-enhanced spiral computed tomography (CT) during follow-up at 1 week, and 3, 6 and 12 months. RESULTS: Fifty-four patients were studied. Eleven were excluded (two perioperative deaths, seven top endoleaks and two occluder endoleaks). Median follow-up was 2 (range 11-7) months. Of the 17 patients in whom patent vessels were demonstrated on an aneurysmograph, one had a patent IMA only, three had a patent LA and IMA, and the remainder had a patent LA. No patient within the study has had a LA or IMA endoleak identified at follow-up CT. CONCLUSION: An intraoperative aneurysmograph can help select patients for aneurysm sac packing with gelatin sponge and has been successful in the short term in preventing LA and IMA endoleaks.

A prospective study to assess changes in proximal aortic neck dimensions after endovascular repair of abdominal aortic aneurysms.

OBJECTIVE: The purpose of this study was to detect any change in the proximal neck diameter after endovascular repair of abdominal aortic aneurysm. METHODS: The study was performed in a teaching hospital with an endovascular program on 112 patients who had undergone endovascular repair of abdominal aortic aneurysm. The interventions were pre-endovascular and postendovascular repair of abdominal aortic aneurysms with contrast-enhanced, spiral computerized tomography, and the main outcome measures were change in aortic proximal neck diameter, change in maximum aortic diameter, presence of endoleaks, and change in length from lowest renal artery to aortic bifurcation. RESULTS: The median anterior-posterior and transverse diameter decreased from 63.5 mm before surgery to 50.4 and 54.5 mm, respectively, after surgery in a period of 4 years. This trend in reduction in maximum diameter was not seen in the patients with endoleaks. There was no significant change in the proximal neck diameters when measured at 5-mm intervals after endovascular repair. There was also no significant change in the aortic length after endovascular repair. CONCLUSION: We have not demonstrated any evidence for proximal neck dilatation after endovascular repair of abdominal aortic aneurysm.

Endovascular AAA repair: prevention of side branch endoleaks with thrombogenic sponge.

PURPOSE: To report a technique that might decrease the incidence of lumbar artery endoleaks following endovascular repair (EVR) of abdominal aortic aneurysms (AAAs). METHODS: Ninety-three patients (86 males, median age 72 years, range 56 to 88) undergoing EVR with the aortomonoiliac technique were entered into a study to detect and then occlude patent side branches before completion of the endografting procedure. Prior to deploying the iliac occluder, an aneurysmogram was performed to detect patent aortic side branches. If these side branches were found, an absorbable gelatin sponge was inserted into the aneurysm sac via the occluder introducer sheath. The patients were followed with contrast-enhanced spiral computed tomography (CT) at 1 week and 3, 6, and 12 months to detect the presence of endoleaks. RESULTS: Forty-eight (52%) patients demonstrated patent side branches that were occluded by the insertion of gelatin sponges into the aneurysm sac. The remaining 45 patients without evidence of side branch flow were untreated. Ten (10.7%) patients died in the perioperative period, and 15 (16.1%) primary endoleaks (13 proximal, 2 distal) were detected. This left 68 (73.1%) patients for follow-up, 33 (48.5%) of whom had patent branch vessels treated with the thrombogenic sponge. The median follow-up was 4 months (range 1 to 17), during which time no side branch endoleak was detected on surveillance CT scans in any of the 68 patients, which included all patients treated with the thrombogenic sponge technique and those in whom no patent side branches had been identified. CONCLUSIONS: We have demonstrated a safe and reliable method of preventing lumbar artery endoleaks following endovascular AAA repair.