EVAR deployment in anatomically challenging necks outside the IFU.

OBJECTIVE: Treatment of abdominal aortic aneurysms with high-risk anatomy (neck length <10-15 mm, neck angle >60°) using commercially available devices has become increasingly common with expanding institutional experience. We examined whether placement of approved devices in short angled necks provides acceptable durability at early and intermediate time points. METHODS: A total of 218 patients (197 men, 21 women) at a single academic center underwent endovascular aneurysm repair (EVAR) with a commercially available device between January 2004 and December 2007. Available medical records, pre- and postoperative imaging, and clinical follow-up were retrospectively reviewed. Patients were divided into those with suitable anatomy (instructions for use, IFU) for EVAR and those with high-risk anatomic aneurysm characteristics (non-IFU). RESULTS: IFU (n = 143) patients underwent repair with Excluder (40%), AneuRx (34%), and Zenith (26%) devices, whereas non-IFU (n = 75) were preferentially treated with Zenith (57%) over Excluder (25%) and AneuRx (17%). Demographics and medical comorbidities between the groups were similar. Operative mortality was 1.4% (2.1% IFU, 0% non-IFU) with mean follow-up of 35 months (range 12-72). Non-IFU patients tended to have larger sac diameters (46.7% ≥60 mm) with shorter (30.7% ≤10 mm), conical (49.3%), and more angled (68% >60°) necks (all p < .05 compared with IFU patients). Operative characteristics revealed that the non-IFU patients were more likely to be treated utilizing suprarenal fixation devices, to require placement of proximal cuffs (13.3% vs. 2.1%, p = .003), and needed increased fluoroscopy time (31 vs. 25 minutes, p = .02). Contrast dose was similar between groups (IFU = 118 mL, non-IFU = 119 mL, p = .95). There were no early or late surgical conversions. Rates of migration, endoleak, need for reintervention, sac regression, and freedom from aneurysm-related death were similar between the groups (p > .05). CONCLUSIONS: EVAR may be performed safely in high-risk patients with unfavorable neck anatomy using particular commercially available endografts. In our experience, the preferential use of active suprarenal fixation and aggressive use of proximal cuffs is associated with optimal results in these settings. Mid-term outcomes are comparable with those achieved in patients with suitable anatomy using a similar range of EVAR devices. Careful and mandatory long-term follow-up will be necessary to confirm the benefit of treating these high-risk anatomic patients.

EVAR using the Nellix Sac-anchoring endoprosthesis: treatment of favourable and adverse anatomy.

OBJECTIVE: The study aimed to review the results of endovascular aneurysm repair (EVAR) using a novel sac-anchoring endoprosthesis in patients with favourable and adverse anatomy. DESIGN: This is a prospective, multicentre, clinical trial. MATERIALS: The Nellix endoprosthesis consists of dual, balloon-expandable endoframes, surrounded by polymer-filled endobags, which obliterate the aneurysm sac and maintain endograft position. METHODS: The study reviewed worldwide clinical experience and Core Lab evaluation of computed tomography (CT) scans. RESULTS: From 2008 to 2010, 34 patients (age 71 ± 8 years, abdominal aortic aneurysm (AAA) diameter 5.8 ± 0.8 cm) were treated at four clinical sites. Seventeen patients (50%) met the inclusion criteria for Food and Drug Administration (FDA)-approved endografts (favourable anatomy); 17 (50%) had one or more adverse anatomic feature: neck length <10 mm (24%), neck angle >60° (9%) and iliac diameter >23 mm (38%). Device deployment was successful in all patients; iliac aneurysm treatment preserved hypogastric patency. Perioperative mortality was 1/34 (2.9%); one patient died at 10 months of congestive heart failure (CHF); one patient had a secondary procedure at 15 months. During 15 ± 6 months follow-up, there were no differences in outcome between favourable and adverse anatomy patients. Follow-up CT extending up to 2 years revealed no change in aneurysm size or endograft position and no new endoleaks. CONCLUSIONS: Favourable and adverse anatomy patients can be successfully treated using the Nellix sac-anchoring endoprosthesis. Early results are promising but longer-term studies are needed.

Ruptured abdominal aortic aneurysm: a surgical emergency with many clinical presentations.

Ruptured abdominal aortic aneurysm (AAA) is one of the most fatal surgical emergencies, with an overall mortality rate of 90%. Most AAAs rupture into the retroperitoneal cavity, which results in the classical triad of pain, hypotension, and a pulsatile mass. However, this triad is seen in only 25-50% of patients, and many patients with ruptured AAA are misdiagnosed. It is likely that different sites of rupture of AAA determine a variety of common and uncommon clinical presentations, the recognition of which can save many lives. This article reviews the different sites of rupture of infrarenal AAA and explores the evidence behind the various clinical presentations seen in patients with ruptured AAA.

Outcome of open versus endovascular revascularization for chronic mesenteric ischemia: review of comparative studies.

Chronic mesenteric ischemia is a rare disorder that has traditionally been treated with open surgical revascularization (OR). Endovascular revascularization (ER) has recently gained popularity as an alternative modality of treatment; however, OR is still predominantly used. This study aimed at comparing the outcomes of these two treatment modalities. The literature was searched using the MEDLINE database through the PubMed search engine for relevant articles that compared the outcomes after OR and ER for chronic mesenteric ischemia. Review of the selected articles revealed that patients had lower postoperative mortality and morbidity, and shorter intensive care unit and hospital stay after ER. However, early and long-term symptomatic relief and significantly lower restenosis rate were characteristic of OR. Although no level 1 evidence governs the treatment of chronic mesenteric ischemia, the durability and efficacy of OR is such that this modality should remain the procedure of choice for patients who are fit or whose fitness could be improved before surgery. For unfit patients, or those with short life expectancy, ER is preferable owing to its minimally invasive nature and reduced postoperative mortality and morbidity. Randomized controlled studies are needed to compare the long-term durability and efficacy of ER to those of OR.

The association between iliac fixation and proximal stent-graft migration during EVAR follow-up: mid-term results of 154 Talent devices.

OBJECTIVE: This study investigated the importance of iliac fixation to secure endograft fixation. MATERIALS AND METHODS: Computed tomography (CT) scans of patients who underwent endovascular aneurysm repair with an endoprosthesis of great columnar strength (Talent stent graft) were analysed retrospectively. Patients were enrolled consecutively between June 2000 and January 2007 and prospectively followed up with serial CT imaging. The superior mesenteric artery was used as a reference point to determine endograft migration (centerline endograft displacement of >or=10mm). Proximal and distal fixation lengths were defined as the length of the endograft that was in full apposition to the aortic neck or common iliac arteries, respectively. RESULTS: Proximal endograft migration occurred in 32 of 154 patients (21%) at a follow-up duration of 32+/-14 months; 13 migrations required treatment (8%). Migration was more frequent in patients treated with aorto-uniiliac devices than bifurcation devices (p<0.008). The migrator and non-migrator groups had similar demographic and abdominal aortic aneurysm (AAA) characteristics. The migrator group had significantly shorter proximal (30+/-12 mm vs. 41+/-13 mm, P<0.001) and distal endograft fixation lengths (31+/-18 mm vs. 47+/-15 mm, P<0.001). By multivariate regression analysis, proximal and distal endograft fixations were significant predictors for endograft migration at follow-up (P<0.001). CONCLUSION: Iliac endograft fixation, along with proximal fixation, is a significant predictor for endograft migration.

Endovascular proximal control of ruptured abdominal aortic aneurysms: the internal aortic clamp.

Ruptured abdominal aortic aneurysm (RAAA) is the most common and devastating complication affecting a patient with abdominal aortic aneurysm (AAA). Despite advances in surgery and critical care, the mortality rate associated with RAAA remains largely unchanged. Emergency open repair is the gold standard conventional treatment of RAAA but is associated with a high mortality rate. The physiologic challenges associated with general anaesthetic induction such as loss of the sympathetic vasoconstrictor tone with consequent hypotension, and the anatomic challenges associated with external aortic cross-clamping such as calcification, friability, or poor visualisation of the aneurysm neck, have led to the adoption of endovascular techniques in the surgical treatment of RAAA. Promising results of endovascular repair of ruptured abdominal aortic aneurysm (REVAR) have been reported. In addition, the provision of endovascular aortic control by inflating a compliant aortic occlusion balloon (AOB) proximal to the ruptured aneurysm, as an internal aortic clamp, has been successfully used in haemodynamically unstable patients undergoing either REVAR or emergency open repair of RAAA. An AOB is inserted under local anaesthesia and can be introduced through either the transbrachial or the transfemoral routes, each with its own advantages and disadvantages. This review aimed at providing an up-to-date overview of the current knowledge concerning endovascular proximal aortic control using an AOB with emphasis on the rationale, position, benefits, and drawbacks of its use.

Polymethylmethacrylate (PMMA) as an embedding medium preserving tissues and foreign materials encroaching in endovascular devices.

Problems of displacement, poor healing, degradation of the polymers and corrosion of the metallic frame in endovascular devices still require in-depth investigations. As the tissues and the foreign materials are in close contact, it is of paramount importance to efficiently investigate the interfaces between them. Inclusion in polymethymethacrylate (PMMA) permits us to obtain thin slides and preserve the capacity to perform the appropriate stainings. An AneuRx prosthesis was harvested in bloc with the surrounding tissues at the autopsy of a patient 25 months post deployment in a 5.7 cm diameter AAA and sectioned in the direction of the blood flow in two halves. A cross-section of the encapsulated distal segment together with the surrounding aneuryshmal sac was embedded in polymethylmethacrylate (PMMA). Further to complete polymerization, slices of the specimen were cut on a precision banding saw under coolant. They were affixed onto methacrylate slides with a UV cured adhesive. Binding and polishing were done on a numeric grinder and slices 25 to 30 microm in thickness were stained with toluidine blue prior to observation in light microscopy. Additional slices were prepared for scanning electron microscopy and X-ray energy dispersive spectrometry for determination of the elemental composition of the Nitinol stent. The aortic wall did not demonstrate complete integrity along with its circumference. Some areas of rupture were noted. The content of the sac was heavily shrunk and was mostly acellular. The walls of the device were very well encapsulated. The PMMA embedding permitted the polyester wall, the Nitinol wire and the collagen to keep in close contact. Scanning electron microscopy involved backscattered electrons and confirmed the corrosion the Nitinol wire at the boundary with living tissues. Based upon the results obtained, we believe that PMMA embedding is the most appropriate method to process endovascular devices for histological and material investigation. Needless to say, that paraffin embedding would have not been feasible for such a big size specimen involving different materials.

MRI virtual biopsies: analysis of an explanted endovascular device and perspectives for the future.

Information that can be obtained by magnetic resonance imaging (MRI) of explanted endovascular devices must be validated as this method is non-destructive. Histology of such a device together with its encroached tissues can be elegantly performed after polymethymethacrylate (PMMA) embedding, but this approach requires destruction of the specimen. The issue is therefore to determine if the MRI is sufficient to fully validate an explanted device based upon the characterization of an explanted specimen. An AneuRx device deployed percutaneously 25 months earlier in a 75-year-old patient was removed en bloc at autopsy together with the surrounding aneurysmal sac and segments of the upstream and downstream arteries. Macroscopic pictures were taken and a slice of the cross-section was processed for histology after polymethylmethacrylate (PMMA) embedding. For the magnetic resonance imaging investigation, the device was inserted in a Biospec 4.7 T MRI system with a 20 mm diameter birdcage resonator used for both emission and reception. A Spin-Echo (SE) was used to acquire both T1 proton density (PD) and T2 weighted images. A gradient-echo (GE) sampling of a free induction decay (GESFID) was used to generate multiple GE images using a single excitation pulse so that four images at different TE were obtained in the same acquisition. The selected explanted device was outstandingly well-healed compared to most devices harvested from humans. No inflammatory process was observed in contact or at distance of the materials. In MRI T1 images display no specific contrast and were homogeneous in the different tissues. The contrast was improved on proton density weighed images. On the T2 weighed images, the different areas were well identified. The diffusion images displayed in the surrounding B region had the greatest diffusion coefficient and the greatest anisotropy. The MRI analysis of the explanted AneuRx device illustrates the possibilities of this technique to characterize the interaction of the endovascular graft with the surrounding tissues. MRI is a breakthrough to investigate explanted medical devices but it also can be advantageously used in vivo to obtain virtual biopsies, because real biopsies to determine the 3 Bs (biocompatibility, biofunctionality and bioresilience) cannot be carried out as they could obviously initiate infection and degradation of the foreign materials.

Keyhole technique for autologous brachiobasilic transposition arteriovenous fistula.

BACKGROUND: Autologous brachiobasilic transposition arteriovenous fistulas (AVFs) are desirable but require long incisions and extensive surgical dissection. To minimize the extent of surgery, we developed a catheter-based technique that requires only keyhole incisions and local anesthesia. METHODS: The technique involves exposure and division of the basilic vein at the elbow. A guidewire is introduced into the vein, and a 6F "push catheter" is advanced over the guidewire and attached to the vein with sutures. Gently pushing the catheter proximally inverts, or intussuscepts, the vein. Side branches that are felt as resistances when pushing the catheter forward are localized, clipped, and divided under direct vision. Throughout the procedure, the endothelium always remains intraluminal. The basilic vein is externalized at the axilla without dividing it proximally and is tunneled subcutaneously, where it is anastomosed to the brachial artery. RESULTS: Thirty-two patients underwent the procedure--31 as outpatients. The mean duration of operation was less than 90 minutes. All patients tolerated the procedure well, and 31 required only intravenous sedation and local anesthesia. At a mean follow-up of 8 months, the primary patency rate of AVFs in patients with basilic vein diameters of 4 mm or more on preoperative duplex ultrasonography was 80%, vs 50% for those with vein diameters less than 4 mm. Overall, 78% of patent AVFs were being successfully accessed and 22% were still maturing at last follow-up. CONCLUSIONS: Autologous brachiobasilic transposition AVFs can be created by using catheter-mediated techniques that facilitate the mobilization and tunneling of the basilic vein through small incisions. Medium-term data suggest that the inversion method results in acceptable maturation and functionality of AVFs created with this technique.

Endografting of the abdominal aorta and iliac arteries for occlusive disease.

Angioplasty and stenting of short segment obstructions is highly effective in the treatment of aorto-iliac occlusive disease. However, long-segment, diffuse and calcific aorto-iliac atherosclerosis is most effectively treated with surgical bypass. While aorto-femoral bypass procedures are durable and effective, too often patients are elderly, high risk and poor candidates for open surgery. Endografting of the abdominal aorta and iliac arteries is aimed at improving the short and long-term results of endovascular treatment of extensive, end-stage aorto-iliac disease. Aorto-iliac endografts are widely used in the treatment of aneurysmal disease. Early experiences with endografts in the treatment of occlusive disease are promising. However, evidence that long-term patency of endografts will be substantially better than angioplasty and stenting is not yet available. Prospective clinical trials are needed to determine the role of endografts in the treatment strategy of aorto-iliac occlusive disease.

Endovascular repair or surveillance of patients with small AAA.

OBJECTIVE: To compare the outcome of patients with small abdominal aortic aneurysms (AAA) treated in a prospective trial of endovascular aneurysm repair (EVAR) to patients randomized to the surveillance arm of the UK Small Aneurysm Trial. METHOD: All patients with small AAA (< or = 5.5 cm diameter) treated with a stent graft (EVARsmall) in the multicenter AneuRx clinical trial from 1997 to 1999 were reviewed with follow up through 2003. A subgroup of patients (EVARmatch) who met the age (60-76 years) and aneurysm size (4.0-5.5 cm diameter) inclusion criteria of the UK Small Aneurysm Trial were compared to the published results of the surveillance patient cohort (UKsurveil) of the UK Small Aneurysm Trial (NEJM 346:1445, 2002). Endpoints of comparison were aneurysm rupture, fatal aneurysm rupture, operative mortality, aneurysm related death and overall mortality. The total patient years of follow-up for EVAR patients was 1369 years and for UK patients was 3048 years. Statistical comparisons of EVARmatch and UKsurveil patients were made for rates per 100 patient years of follow up (/100 years) to adjust for differences in follow-up time. RESULTS: The EVARsmall group of 478 patients comprised 40% of the total number of patients treated during the course of the AneuRx clinical trial. The EVARmatch group of 312 patients excluded 151 patients for age < 60 or > 76 years and 15 patients for AAA diameter < 4 cm. With the exception of age, there were no significant differences between EVARsmall and EVARmatch in pre-operative factors or post-operative outcomes. In comparison to the UKsurveil group of 527 patients, the EVARmatch group was slightly older (70 +/- 4 vs. 69 +/- 4 years, p = 0.009), had larger aneurysms (5.0 +/- 0.3 vs. 4.6 +/- 0.4 cm, p < 0.001), fewer women (7 vs. 18%, p < 0.001), and had a higher prevalence of diabetes and hypertension and a lower prevalence of smoking at baseline. Ruptures occurred in 1.6% of EVARmatch patients and 5.1% of UKsurveil patients; this difference was not significant when adjusted for the difference in length of follow up. Fatal aneurysm rupture rate, adjusted for follow up time, was four times higher in UKsurveil (0.8/100 patient years) than in EVARmatch (0.2/100 patient years, p < 0.001); this difference remained significant when adjusted for difference in gender mix. Elective operative mortality rate was significantly lower in EVARmatch (1.9%) than in UKsurveil (5.9%, p < 0.01). Aneurysm-related death rate was two times higher in UKsurveil (1.6/100 patient years) than in EVARmatch (0.8/100 patient years, p = 0.03). All-cause mortality rate was significantly higher in UKsurveil (8.3/100 patient years) than in EVARmatch (6.4/100 patient years, p = 0.02). CONCLUSIONS: It appears that endovascular repair of small abdominal aortic aneurysms (4.0-5.5 cm) significantly reduces the risk of fatal aneurysm rupture and aneurysm-related death and improves overall patient survival compared to an ultrasound surveillance strategy with selective open surgical repair.

Short- and long-term outcome following endovascular aneurysm repair. How does it compare to open surgery?

The primary objective of aneurysm repair is to prevent aneurysm rupture while avoiding aneurysm-related death. This manuscript reviews the primary and secondary outcome measures following endovascular aneurysm repair (EVAR) in relation to similar outcome measures for open surgical repair. Both EVAR and open repair are effective in preventing aneurysm rupture, although late ruptures can occur with either treatment method. The late risk of rupture following EVAR is less that 1% per year using current endovascular devices. Aneurysm-related death rate appears to be lower following EVAR compared to open surgery, primarily due to a lower perioperative mortality rate. Actuarial 5-year survival after both endovascular and open aneurysm repair is approximately 70%. Perioperative outcome measures favor EVAR over open repair for patients with suitable anatomy with reduced morbidity and more rapid patient recovery. Short and long-term outcomes following endovascular repair compare favorably to open repair. However, prospective studies are needed to better define the long-term outcomes using comparable endpoints.

Aortoiliac angulation and the need for secondary procedures to secure stent graft fixation: which angle is important?

BACKGROUND: The purpose of this study was to quantify the degree of aortoiliac tortuosity and determine the relationship between aortoiliac angulation and the need for a secondary procedure following endovascular repair. METHODS: Among 206 patients treated with the AneuRx stent graft, 3-year follow up data were available in 71 patients. Twenty eight patients without duplex and CT angiograms (CT angiography) on follow-up were excluded. The anatomy of the preoperative proximal aortic neck was evaluated using 3D-CT angiography reconstructed images in: a) Group I: 15 patients who required secondary procedures and b) Group II: 18 patients without any endovascular leak during follow up. The groups did not differ in age (72.9+/-6.1 versus 73.3+/-9.1) or aneurysm diameter (60.1+/-9.1 versus 60.5+/-10.1). In order to determine the aortoiliac tortuosity, we measured: a) the suprarenal aorta-infrarenal aortic neck angle: angle of the aorta at the level of the renal arteries, b) infrarenal aortic neck-aneurysm angle: angle of the aorta at the start of aneurysm, c) right iliac angle, d) left iliac angle, e) aortic neck length, f) aortic neck diameter. RESULTS: Computer-based measurements on 3D-CT angiography reconstructed images were: a) suprarenal aorta-infrarenal aortic neck angle: group I: (22.6+/-16.2), group II: (11.9+/-6.9), p<0.05; b) infrarenal aortic neck-aneurysm angle: group I: 17.6+/-12.4, group II: 18.8+/-9.4, p=NS; c) right iliac angle: group I: 22.9+/-12.6, group II: 20.4+/-9.5, p=NS; d) left iliac angle: group I: 22.4+/-10.5, group II: 19.1+/-12.2, p=NS; e) aortic neck length: group I: 18.9+/-5.3 mm, group II: 20.4+/-5.3 mm, p=NS; f) aortic neck diameter: group I: 24.1+/-1.0 mm, group II: 23.3+/-1.6, p=NS. CONCLUSIONS: Aortoiliac angulation can be defined and quantified. In patients requiring secondary procedures, there is an increased angulation at the proximal aortic neck angle.

Impact of endovascular repair on open aortic aneurysm surgical training.

PURPOSE: The purpose of this study was to determine the impact of an endovascular stent-graft program on vascular training in open aortic aneurysm surgery. METHODS: The institutional and vascular surgery fellow experience in aortic aneurysm repair during a 6-year period was reviewed. The 3-year period before introduction of endovascular repair was compared with the 3-year period after introduction of endovascular repair. All patients undergoing abdominal aortic aneurysm (AAA) or thoracoabdominal aortic aneurysm repairs were entered prospectively into a vascular registry and retrospectively analyzed to evaluate the changing patterns in aortic aneurysm treatment and surgical training. RESULTS: Between July 1994 and June 2000, a total of 588 patients with AAA or thoracoabdominal aneurysms were treated at Stanford University Medical Center. There were 296 (50%) open infrarenal AAA repairs, 87 (15%) suprarenal AAA repairs, 47 (8%) thoracoabdominal aneurysm repairs, and 153 (26%) endovascular stent-grafts. The total number of aneurysms repaired per year by vascular fellows before the endovascular program was 71.3 +/- 4.9 (range, 68-77) and increased to 124.7 +/- 35.6 (range, 91-162) after introduction of endovascular repair (P <.05). This increase was primarily caused by the addition of endovascular stent-graft repairs by vascular fellows (51.0 +/- 29.0/year [range, 23-81]). There was no change in the number of open infrarenal aortic aneurysm repairs per year, 53.0 +/- 6.6 (range, 48-56) before endovascular repair versus 47.0 +/- 1.7 (range, 46-49) after (P = not significant). There was a significant increase in the number of suprarenal AAA repairs per year by vascular fellows, 10.0 +/- 1.0 (range, 9-11) before endovascular repair compared with 19.0 +/- 6.5 (range, 13-26) after (P <.05). There was no change in the number of thoracoabdominal aneurysm repairs per year between the two groups, 8.0 +/- 3.0 (range, 4-11) before endovascular repair compared with 7.6 +/- 2.3 (range, 5-9) after. CONCLUSIONS: Introduction of an endovascular aneurysm stent-graft program significantly increased the total number of aneurysms treated. Although the number of open aneurysm repairs has remained the same, the complexity of the open aneurysm experience has increased significantly for vascular fellows in training.

Type-II endoleaks following endovascular AAA repair: preoperative predictors and long-term effects.

PURPOSE: To determine the significance of persistent type-II endoleaks and whether they can be predicted preoperatively in patients with abdominal aortic aneurysms (AAA). METHODS: The charts of all AAA patients treated with the AneuRx stent-graft at a single center from 1996 to 1998 were reviewed. Patients with <12-month follow-up or type-I endoleaks were excluded. The presence or absence of type-II endoleaks was determined from duplex imaging and computed tomographic angiography. Three groups were identified and compared: 16 patients with persistent type-II endoleaks (PE), 14 patients with transient type-II endoleaks (TE), and 16 patients with no endoleak (NE). RESULTS: The groups did not differ with regard to age, preoperative comorbidities, follow-up time, and AAA neck diameter and length. AAA diameters were 57.1 +/- 9.0 mm for NE, 63.4 +/- 11.4 mm for TE, and 55.6 +/- 4.2 mm for PE. The inferior mesenteric artery (IMA) was patent in 5 (31%) NE patients, 6 (43%) TE patients, and 13 (81%) PE patients (p < 0.01). The number of patent lumbar arteries visualized preoperatively was 0.5 +/- 1.0 in NE, 1.3 +/- 0.8 in TE, and 2.4 +/- 0.6 in PE (p < 0.0001). Patent IMAs (RR 0.82, p < 0.01) and >2 lumbar arteries (RR 0.40, p < 0.0001) were identified as independent preoperative risk factors for persistent endoleaks. There were no changes in mean diameter or volume in aneurysms with persistent endoleaks. CONCLUSIONS: No adverse clinical events were related to the presence of type-II endoleaks, but there was no decrease in aneurysm size in patients with persistent type-II leaks. Patients with a large, patent IMA, or >2 lumbar arteries on preoperative CT angiography are at higher risk for persistent type-II endoleaks.

Impact of aortoiliac tortuosity on endovascular repair of abdominal aortic aneurysms: evaluation of 3D computer-based assessment.

OBJECTIVE: The purpose of this study was to examine the effect of aortoiliac tortuosity, as assessed by observers and 3-dimensional (3D) computer-based methods, on the conduct and outcome of endovascular repair of abdominal aortic aneurysms. METHODS: Infrarenal aortoiliac tortuosity was measured in 75 patients (mean follow-up, 14.8 +/- 10.4 months) who underwent endovascular repair of abdominal aortic aneurysms by using the following four methods: (1) grading by 2 experienced observers; (2) tortuosity index measured as the inverse radius of curvature (cm(-1)) at 1-mm intervals along the median luminal centerline (MLC) on 3D reconstructions of computed tomography (CT) angiograms and was calculated as the sum of values greater than 0.3 cm(-1); (3) MLC-straight line length ratio from renal to hypogastric arteries; (4) manual measurement of angles at points of angulation on anteroposterior and lateral projections of 3D CT reconstructions. In evaluating association between these measures, correlation between human observers was accepted as the gold standard. RESULTS: For rating of overall aortoiliac tortuosity, interobserver correlation (r = 0.67) was comparable with correlation of observers with tortuosity index (r = 0.67 and 0.56), whereas correlations of each observer with MLC-straight line ratio (r = 0.50 and 0.56) and cumulative angulation (r = 0.44 and 0.44) were significant but weaker. For determining the relative tortuosity of right and left aortoiliac access, agreement between observers and tortuosity index (54% and 58%; P < .05; kappa, 0.33 and 0.38) was not as good as between observers (68%; P < .001; kappa, 0.53). This difference was primarily related to evaluation of the aorta, where interobserver correlation (r = 0.71) was better than that between each observer and tortuosity index (r = 0.47 and 0.55), whereas correlations in the iliac arteries were comparable (r = 0.64 and 0.67) (all coefficients P < .01). Increased tortuosity was associated with a more complex endovascular repair, as reflected by longer fluoroscopy time (P = .05), use of more contrast material (P = .03), use of extender modules (P = .04), and more frequent use of arterial reconstruction (P = .01), but was not associated with a higher overall complication rate. Increased tortuosity, when it occurred in the aortic neck, was associated with predischarge endoleak (P = .03) but not with late endoleak, intervention, or aneurysm-related adverse events. CONCLUSION: Aortoiliac tortuosity is associated with increased complexity of endovascular aneurysm repair and with predischarge endoleak but does not appear to affect intermediate-term results. Computer-based 3D measurement of aortoiliac tortuosity is feasible and clinically meaningful. Its ultimate role in relation to human assessment must be further defined in future studies.

Prediction of aortoiliac stent-graft length: comparison of measurement methods.

PURPOSE: To determine the accuracy of helical computed tomography (CT), projectional angiography derived from CT angiography, and intravascular ultrasonographic withdrawal (IUW) length measurements for predicting appropriate aortoiliac stent-graft length. MATERIALS AND METHODS: Helical CT data from 33 patients were analyzed before and after endovascular repair of abdominal aortic aneurysm (Aneuryx graft, n = 31; Excluder graft, n = 2). The aortoiliac length of the median luminal centerline (MLC) and the shortest path (SP) that remained at least one common iliac arterial radius away from the vessel wall were calculated. Conventional angiographic measurements were simulated from CT data as the length of the three-dimensional MLC projected onto four standard viewing planes. These predeployment lengths and IUW length, available in 24 patients, were compared with the aortoiliac arterial length after stent-graft deployment. RESULTS: The mean error values of SP, MLC, the maximum projected MLC, and IUW were -2.1 mm +/- 4.6 (SD) (P =.013), 9.8 mm +/- 6.8 (P <.001), -5.2 mm +/- 7.8 (P <.001), and -14.1 mm +/- 9.3 (P <.001), respectively. The preprocedural prediction of the postprocedural aortoiliac length with the SP was significantly more accurate than that with the MLC (P <.001), maximum projected MLC (P <.001), and IUW (P <.001). CONCLUSION: The shortest aortoiliac path length maintaining at least one radius distance from the vessel wall most accurately enabled stent-graft length prediction for 31 AneuRx and two Excluder stent-grafts.

Blood flow decrease induces apoptosis of endothelial cells in previously dilated arteries resulting from chronic high blood flow.

We investigated apoptosis of endothelial cells during the arterial narrowing process in response to reduction in flow. The decrease in flow was created in the carotid artery by closure of an arteriovenous fistula (AVF), which had been established for 28 days in rabbits. The endothelial cell apoptosis in the carotid artery was studied at 1, 3, 7, and 21 days of flow reduction after closure of the AVF by use of terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) with laser scanning confocal microscopy and transmission and scanning electron microscopy. After AVF closure, arterial lumen diameter was reduced by 36%, and compared with endothelial cells before the closure, the number of endothelial cells was decreased by 45% at 21 days. Endothelial cell apoptosis was observed at 1 day, peaked at 3 days (381.3+/-87.1 cells per square millimeter), and decreased at 7 days. These cells had irregular protrusions under scanning electron microscopy and were characterized by fragmented nuclei under transmission electron microscopy. Apoptotic cells were mainly beneath the endothelium and were occasionally within smooth muscle cells and endothelial cells. The results suggest that apoptosis of endothelial cells may play a role in the arterial remodeling in response to a reduction in flow.