Current status of open versus endovascular stent-graft repair of abdominal aortic aneurysm

Primary and secondary aortoenteric fistulas in a patient with abdominal aortic aneurysm

INTRODUCTION

Aortoenteric fistulas (AEF) are infrequent malignant complications of abdominal aortic aneurysms (AAA). We present a unique case of a patient with recurring AAA fistulisations.

PRESENTATION OF CASE

During oncologic treatment, a 63-year-old male was incidentally diagnosed with infrarenal AAA and assigned follow-up but was hospitalised with anaemia and elevated inflammation markers 14 months later. A CT-angiography scan detected an AAA enlargement, but no extravasation (negative FOBT). Another CTA-scan displayed a pseudoaneurysm and ruptured AAA 10 days later. During a total laparotomy, an enlarged pulsating inflammatory conglomerate without active leakage was detected, with a 2 cm duodenal defect (PAEF). The AAA was resected and replaced by a linear silver-coated Dacron graft. 3,5 years after PAEF, the patient was hospitalised with abdominal pain and haematemesis. He underwent gastroscopies, coloscopies, CT- and CTA-scans - all without significant findings. Only after the capsule-endoscopy detected a jejunal ulcer, the PET-scan visualized active regions in the jejunum and the aortic graft. A total laparotomy was performed; previous stapler-lined jejuno-jejunal anastomosis had adhered to the silver-coated Dacron graft (SAEF). The Dacron graft was removed and replaced with a linear xenograft from bovine pericardium.

DISCUSSION

No evidence-based recommendations prefer endovascular aneurysm repair (EVAR) over open repair, leaving the strategy dependent on local preferences. Whether EVAR or initial xenograft usage would have shown surpassing results, is speculative, as no graft material/type has proved long-term pre-eminence.

CONCLUSIONS

This case displays AEF's complex treatment and challenging diagnosis. Multimodal diagnostic and strategic approaches should be considered for best patient outcome.

Numerical Modeling of Blood Flow in a Healthy Aorta and Aorta with Stent

The treatment of aortic aneurysm varies according to each patient. Stent implantation is one of many methods used to stabilize diseases. The information obtained from hemodynamic parameters in the pathological aorta with stent could help doctors in choosing the treatment before the surgery. In this context, the numerical simulation of fluid dynamics is an essential tool that can give us more detailed information that could be exploited by surgeons to find appropriate solutions to some pathologies. In this work, a study of two models of aortas: with and without stent was presented. A comparison of the results of changes in pressures and shear stresses of aortas in systolic and diastolic phases was discussed. The obtained results show a nearly similar tendency of variation for both models, which justifies the effectiveness of the type of stent chosen and its effect on the improvement of the blood flow. The methodology used in this work has revealed the detailed and necessary information for both cases studied and has shown the interest of the numerical tools for diagnosis and surgery.

Comparison of Endovascular Stent Grafts for Abdominal Aortic Aneurysm Repair in Medicare Beneficiaries

BACKGROUND

Increased renal complications have been suggested with suprarenal stent grafts, but long-term analyses have been limited. Therefore, the purpose of this study was to evaluate the effect of endograft choice on perioperative and long-term outcomes.

METHODS

We compared Medicare beneficiaries undergoing endovascular abdominal aortic aneurysms repair from 2005 to 2008 with endografts with infrarenal fixation and a single docking limb (AneuRx, Excluder) to those with suprarenal fixation and 2 docking limbs (Zenith), or a unibody configuration (Powerlink). Propensity score weighting accounted for differences in patient characteristics among the different graft formations, and perioperative mortality, complications, and length of stay and 4-year rates of survival, rupture, and reintervention were compared.

RESULTS

Forty-six thousand one hundred seventy-one Medicare beneficiaries were identified including 11,002 (24%) with suprarenal fixation, 32,909 (71%) with infrarenal fixation, and 2,260 (5%) with a unibody graft. After propensity score weighting, there were no significant differences in patients' baseline clinical and demographic characteristics. The suprarenal fixation patients had higher rates of perioperative mortality (1.7% vs. 1.3%, P < 0.01), renal failure (6.0% vs. 4.7%, P < 0.001), and mesenteric ischemia (0.7% vs. 0.4%, P < 0.01) and longer length of stay (3.4 days vs. 3.0 days, P < 0.001) compared with patients with infrarenal fixation. Unibody grafts had higher rates of renal failure (5.9% vs. 4.7%, P < 0.001), mesenteric ischemia (1.0% vs. 0.4%, P < 0.001), and conversion to open repair (0.7% vs. 0.1%, P < 0.001) compared to those with infrarenal fixation and single docking limbs. At 4 years, mortality remained slightly higher with suprarenal compared to infrarenal fixation (30% vs. 29%, P = 0.047), although these patients had fewer conversions to open repair (0.6% vs. 0.9%, P = 0.03) and aneurysm-related reinterventions (10% vs. 12%, P < 0.01). At 4 years, unibody grafts had more aneurysm-related interventions compared to infrarenal fixation grafts (15% vs. 12%, P < 0.01) but fewer conversions to open repair (0.4% vs. 0.9%, P = 0.02). Late rupture did not differ among the groups.

CONCLUSIONS

Compared to infrarenal fixation devices, patients who underwent EVAR with suprarenal fixation had higher perioperative mortality and renal complications but fewer reinterventions including conversion, while the unibody graft had more perioperative complications and aneurysm-related reinterventions, but fewer conversions to open repair. Although these differences could be explained by selection bias, these data suggest that further comparative effectiveness analyses should be performed to understand the outcomes following EVAR with suprarenal fixation and unibody grafts.

EVAR and OPEN treatment of abdominal aortic aneurysm: What is the role of MMP-9 in the follow-up?

INTRODUCTION

The aim of our study is to verify the role of metalloproteinases in endovascular repair (EVAR) and OPEN surgery treatment for abdominal aortic aneurysm (AAA). Postoperatively, these enzymes could represent an important biomarker to adapt diagnostic tests and further investigations during follow-up.

MATERIAL AND METHOD

From 2004 to 2008, 55 patients were considered with AAA. Of these, 33 patients (mean age: 70.1 years), (mean AAA diameter: 5.4cm) were treated with OPEN surgery (group A) and 22 (mean age: 74.1 years) (mean AAA diameter: 5.1cm) were treated with EVAR. In 17 of them, there were no signs of endoleak (group B1), while in 5 patients, a presence of endoleak (group B2) was detected. Plasma samples were collected in order to determine MMP-9 activity. Enzyme immunoassay was performed preoperatively at 1, 3, 6 and 12 months. Patients treated conventionally were clinically examined after 1 and 12 months by ultrasound. Patients undergoing EVAR treatment were clinically examined by CT scan after 1, 3, 6 and 12 months. The analysis was done by assessing the interaction over time of the MMP-9 value in B1 and B2 groups.

RESULTS

The average values observed for MMP-9 were preoperatively and at 1, 3, 6 and 12 months, respectively: in group A 150.8ng/mL (SD=30.5), 252.5ng/mL (SD=25.2), 315.4ng/mL (SD=22.7), 295.3ng/mL (SD=26.8), 210.7ng/mL (SD=30.2); in group B1 105ng/mL (SD=10.8), 125.6ng/mL (SD=18), 85.8ng/mL (SD=19.9), 95ng/mL (SD=20.2), 80.4ng/mL (SD=15.6); in group B2 149ng/mL (29.2), 375.4ng/mL (SD=40.2), 215ng/mL (SD=35.9), 180ng/mL (SD=20.2), 175ng/mL (SD=33.4). The MMP-9 level was higher in group B2 compared to group B1 (P=0.01), suggesting a correlation with the presence of the endoleak.

CONCLUSIONS

This preliminary study shows that MMP-9 may be a biomarker of the presence of endoleak. Other further investigations and larger series are needed to show that metalloproteases could play a role in the follow-up of EVAR treated patients.

Anesthetic considerations for endovascular abdominal aortic aneurysm repair

Aneurysm is defined as a localized and permanent dilatation with an increase in normal diameter by more than 50%. It is more common in males and can affect up to 8% of elderly men. Smoking is the greatest risk factor for abdominal aortic aneurysm (AAA) and other risk factors include hypertension, hyperlipidemia, family history of aneurysms, inflammatory vasculitis, and trauma. Endovascular Aneurysm Repair [EVAR] is a common procedure performed for AAA, because of its minimal invasiveness as compared with open surgical repair. Patients undergoing EVAR have a greater incidence of major co-morbidities and should undergo comprehensive preoperative assessment and optimization within the multidisciplinary settings. In majority of cases, EVAR is extremely well-tolerated. The aim of this article is to outline the Anesthetic considerations related to EVAR.

Experimental Model of Saccular Abdominal Aortic Aneurysm in Swines with Pericardium Sac

OBJECTIVE

To consider modifications in an experimental model of saccular aortic aneurysm, aiming at better reproducibility, to be used in the development of vascular prostheses.

METHODS

Experimental study in two phases, developed in the Center of Experimental Surgery and Bioterium (CCEB) of the University of Health Sciences of Alagoas (UNCISAL), with 11 hybrid swine, female, mean weight of 20 ± 5 kg, according to modifications in the Perini technique was performed. In the first phase, the aneurysm was confectioned with bovine pericardial patch. In the second phase, fifteen days later, the patency of the aneurysms was confirmed by Doppler ultrasonography. The described variables were aortic and aneurysm sac patency, incidence of rupture, morbidity and mortality. The statistical analysis program used was STATA v.8.

RESULTS

All animals survived to the procedures. Surgical mean time was 73 minutes. Aneurysm rupture, proximal or distal aortic thrombosis, visceral or legs ischemia weren't observed. Parietal thrombus formation was observed in all of the aneurysms, two of which (18%; IC 95% = 3.98 - 48.84) were occluded and nine (82%; IC 95% = 51.15 - 96.01) were patent.

CONCLUSION

In this series, the modifications carried out in the technique related to the surgical approach, race, anesthesia, and imaging exams reproduced the experimental model, reducing its costs, without hindering the analysis of the variables. The satisfactory patency ratio allows the method to be used in experimental models for the development of vascular prostheses.

Real-time in vitro intravascular reconstruction and navigation for endovascular aortic stent grafting

BACKGROUND

Trans-catheter endovascular stent grafting minimizes trauma and increases the benefitting patient population. However, the alignment between stent graft branches and vasculature branches remains time-consuming and challenging, and such techniques require a significant amount of contrast agent for imaging.

METHODS

A new framework for intravascular reconstruction based on sensor fusion between intravascular ultrasound (IVUS) imaging and electromagnetic (EM) tracking was proposed. A new image processing method was presented to realize fully automatic processing of IVUS imaging and 3D reconstruction in real time, as well as branch detection for alignment and deployment. Complementary navigation using CT data allows for efficient catheter advancement and assistant clinical judgement.

RESULTS

The reconstruction of an in vitro descending aorta phantom with branches was realized at 35 Hz, with cross-section radius average error of 0.64 mm.

CONCLUSION

The proposed method demonstrates significant potential for clinical applications, enables navigation for precise alignment and placement for stent grafting to reduce surgical time, and decreases hemorrhagic collisions and the use of contrast agent. Copyright © 2016 John Wiley & Sons, Ltd.

Endovascular repair of an aorto-iliac aneurysm succeeded by kidney transplantation

We present the case of aorto-iliac aneurysm in a patient with chronic renal failure requiring dialysis who were treated with an endovascular stent graft and, later on, submitted to kidney transplantation. A 53-year-old male with renal failure requiring dialysis presented with an asymptomatic abdominal aorto-iliac aneurysm measuring 5.0cm of diameter. He was treated with endovascular repair technique, being used an endoprosthesis Excluder®. After four months, he was successfully submitted to kidney transplantation (dead donor), with anastomosis of the graft renal artery in the external iliac artery distal to the endoprosthesis. The magnetic resonance imaging, carried out 30 days after the procedure, showed a good positioning of the endoprosthesis and adequate perfusion of the renal graft. In the follow-up, the patient presented improvement of nitrogenous waste, good positioning of the endoprosthesis without migration or endoleak. The endovascular repair of aorto-iliac aneurysm in a patient with end-stage renal failure under hemodialysis treatment showed to be feasible, safe and efficient, as it did not prevent the success of the posterior kidney transplantation.

Endovascular repair for isolated iliac artery aneurysms: case report and review of the current literature

For a long time, open surgical repair has been considered the preferred management option for the exclusion of isolated iliac artery aneurysms.The development of transluminally placed endovascular stent grafts, which have been studied extensively for aneurysm exclusion in the abdominal and thoracic aorta, provided a less invasive approach for exclusion of iliac artery aneurysms as compared with surgical reconstruction or open surgical graft placement.Here we report a case of concomitant bilateral common and internal iliac artery aneurysms excluded successfully with multiple stent-grafting deployment with extension to the external iliac arteries and without coil embolization requirements.

AAA stent-grafts: past problems and future prospects

Endovascular aneurysm repair (EVAR) has quickly gained popularity for infrarenal abdominal aortic aneurysm repair during the last two decades. The improvement of available EVAR devices is critical for the advancement of patient care in vascular surgery. Problems are still associated with the grafts, many of which can necessitate the conversion of the patient to open repair, or even result in rupture of the aneurysm. This review attempts to address these problems, by highlighting why they occur and what the failings of the currently available stent grafts are, respectively. In addition, the review gives critical appraisal as to the novel methods required for dealing with these problems and identifies the new generation of stent grafts that are being or need to be designed and constructed in order to overcome the issues that are associated with the existing first- and second-generation devices.

Minilaparotomy abdominal aortic aneurysm repair in the era of minimally invasive vascular surgery: preliminary results

BACKGROUND

This study aimed to evaluate the early post-operative clinical impact of minimal incision aortic surgery (MIAS) for infrarenal abdominal aortic aneurysm (AAA) repair in comparison with the standard open repair.

METHODS

A case-control study was conducted. Patients of groups A (19 patients) and B (18 patients) were treated with the MIAS technique and the standard open method, respectively.

RESULTS

There were significant differences between the two groups in fluid resuscitation during the operation. Post-operatively, there were significant differences between groups A and B in the time until starting liquid diet (2 +/- 0.74 versus 3.55 +/- 0.85 post-operative days (PD), respectively; P < 0.05), the time until starting the solid diet (3.05 +/- 0.77 versus 5.11 +/- 0.75 PD, respectively; P < 0.05), the time of ambulation (2 +/- 0.74 versus 3.4 +/- 0.98 PD, respectively; P < 0.05) and in the hospital length of stay (4 +/- 0.81 versus 9.7 +/- 2.66 days, respectively; P < 0.05).

CONCLUSIONS

The MIAS technique, for repair of infrarenal aortic aneurysms, is a safe and feasible procedure that combines the early advantages of endovascular repair with the long-term advantages of the traditional open repair.

DynaCT during EVAR--a comparison with multidetector CT

OBJECTIVES

We have explored the usefulness of an on-table, cross-sectional radiological imaging (DynaCT) in endovascular aortic repair (EVAR). DynaCT images were compared to images from a regular multidetector (16 slice) CT. In the comparison, we tested the accordance of firstly 5 relevant clinical measurements and secondly the visibility of 9 anatomical areas in the two different types of images. This imaging was carried out in addition to the usual angiographic imaging. DESIGN, MATERIAL AND METHOD: 20 patients with infrarenal abdominal aortic aneurysm (AAA) were prospectively enrolled in the study. We compared Images from DynaCT with two different doses of contrast medium to MDCT-images in two different ways. Firstly relevant arterial diameters and lengths and secondly, 9 anatomical areas were evaluated regarding visibility which was scored on a 4-point scale.

RESULTS

There were no significant differences in the measured arterial diameters and lengths. MDCT had a significantly higher visibility score than both DynaCT investigations. However, with the highest contrast medium dose we found acceptable diagnostic quality in 78-94% of the cases for 8 of the 9 investigated anatomical areas.

CONCLUSION

Our findings indicate that on-table DynaCT are of sufficient quality to give relevant information of arterial measurements, needed in endovascular repair of infrarenal aortic aneurysms.

Aneurysm pulsatility after endovascular exclusion--an experimental study using human aortic aneurysms

OBJECTIVE

To measure the pulsatility of human aneurysms before and after complete exclusion with an endograft.

METHOD

Five aortic aneurysms obtained during necropsy were submitted to pulsatile perfusion before and after implantation of a bifurcated endograft. The specimens were contained in a closed chamber filled with saline solution. A vertical tube attached to the chamber was used to measure volume dislocation in each systole. Mural thrombus was kept intact, and the space around the device was filled with human blood. After each experiment, the aneurysm was opened to check for the correct positioning and attachment of the device.

RESULTS

The level of the saline column oscillated during pulsation in each case, with respective amplitudes of 17, 16, 13, 7, and 25 cm before the endograft insertion. After the insertion, the amplitudes dropped to 13, 12, 9, 3.5, and 23 cm, respectively. The differences were not significant. During the post-experimental examination, all devices were found to be in position and well attached to the neck and iliacs. No endoleak was detected during perfusion or by visual inspection.

CONCLUSION

Pulsation of an endograft is transmitted to the aneurysm wall even in the absence of endoleak, and should not be interpreted as procedural failure.

Age stratified, perioperative, and one-year mortality after abdominal aortic aneurysm repair: a statewide experience

OBJECTIVE

The purpose of this study was to determine the in-hospital, 30-day, and 365-day mortality for the open repair of abdominal aortic aneurysms (AAAs), when stratified by age, in the general population. Age stratification could provide clinicians with information more applicable to an individual patient than overall mortality figures.

METHODS

In a retrospective analysis, data were obtained from the California Office of Statewide Health Planning and Development (OSHPD) for the years 1995 to 1999. Out-of-hospital mortality was determined via linkage to the state death registry. All patients undergoing AAA repair as coded by International Classification of Diseases, 9th Revision (ICD-9) procedure code 38.44 and diagnosis codes 441.4 (intact) and 441.3/441.5 (ruptured) in California were identified. Patients <50 years of age were excluded. We determined in-hospital, 30-day, and 365-day mortality, and stratified our findings by patient age. Multivariate logistic regression was used to determine predictors of mortality in the intact and ruptured AAA cohorts.

RESULTS

We identified 12,406 patients (9,778 intact, 2,628 ruptured). Mean patient age was 72.4 +/- 7.2 years (intact) and 73.9 +/- 8.2 (ruptured). Men comprised 80.9% of patients, and 90.8% of patients were white. Overall, intact AAA patient mortality was 3.8% in-hospital, 4% at 30 days, and 8.5% at 365 days. There was a steep increase in mortality with increasing age, such that 365-day mortality increased from 2.9% for patients 51 to 60 years old to 15% for patients 81 to 90 years old. Mortality from day 31 to 365 was greater than both in-hospital and 30-day mortality for all but the youngest intact AAA patients. Perioperative (in-hospital and 30-day) mortality for ruptured cases was 45%, and mortality at 1 year was 54%.

CONCLUSIONS

There is continued mortality after the open repair of AAAs during postoperative days 31 to 365 that, for many patients, is greater than the perioperative death rate. This mortality increases dramatically with age for both intact and ruptured AAA repair.

Are aortic endograft prostheses fully hemo-compatible? A dielectric spectroscopy investigation of the electrical alterations induced on erythrocyte cell membranes

In this paper we present a new approach directed to ascertain the full hemo-compatibility of aortic endograft prostheses based on the measurement of the passive electrical parameters of the erythrocyte cell membrane. The red blood cell membrane, from an electric point of view, is characterized by an electrical permittivity, (s), which takes into account the structural charged organization of the lipid double layer, and by the electrical conductivity, sigma(s), which accounts for the ionic transport processes across the membrane. These parameters can be easily measured by means of a radiowave dielectric spectroscopy technique, analyzing the dependence of the electrical impedance of an erythrocyte suspension on the frequency of the applied electric field. In this preliminary report, we investigate the alterations induced, at a membrane level, by two different devices commonly employed for endovascular abdominal aortic aneurysm exclusion, i.e., Excluder and Zenith devices, implanted in ten patients. We observe, in all the cases investigated, a statistically significant increase of both the permittivity (s) and electrical conductivity sigma(s) of the erythrocyte membrane upon the prosthesis implant, this increase being higher than about 20% of the un-treated values. Moreover, these alterations remain roughly unaffected 30 days after surgery. These findings suggest that a complete hemo-compatibility of these prostheses is lacking, even if the observed alterations may not have a clinical relevance.

Perioperative differences between endovascular repair of thoracic and abdominal aortic diseases

BACKGROUND

With the US Food and Drug Administration approval of the TAG thoracic device, more thoracic pathologies are being treated using endovascular techniques. Although endovascular abdominal and thoracic aortic repairs have some apparent similarities, there are substantive anatomic, pathologic, and technical differences that could impact perioperative outcomes. The purpose of this study is to identify these differences.

METHODS

During a 5-year period, 121 endovascular thoracic aortic repairs (TEVAR) and 450 abdominal aortic repairs (EVAR) were performed at a single institution. Preoperative, intraoperative, and early postoperative data were prospectively collected and retrospectively reviewed. Aggregate outcome measures were compared between the two cohorts, with statistical significance achieved at P < .05.

RESULTS

The mean age of patients undergoing EVAR was 72.8 +/- 8.3 compared with 68.3 +/- 13.9 for TEVAR (P = .02). More women underwent TEVAR (30.6% vs 11.1%, P < .001). Aneurysms undergoing TEVAR were larger than those for EVAR (62.0 mm vs 58.3 mm, P = .01). Intraoperatively, EVAR required 26.2 minutes of fluoroscopy compared with 22.1 minutes for TEVAR (P < .001). The amount of contrast used was higher in TEVAR (133.6 mL vs 93.6 mL, P < .001). The mean procedure times were 164 minutes for EVAR and 115 minutes for TEVAR (P < .001). Iliac conduits were required in 46 patients (10.2%) undergoing EVAR, and in 24 (19.8%) undergoing TEVAR (P = .007). The 30-day or in-hospital mortality was 2.0% for EVAR and 5.0% for TEVAR (P = NS). The median length of stay was longer for TEVAR (3 days vs 2 days, P =.034). There were 54 postoperative complications in 36 TEVAR patients (29.8%), including 13 neurologic (10.7%), 8 renal (6.6%), 7 pulmonary (5.8%), 6 ischemic (5.0), and 5 (4.1%) hemorrhagic events. Among the EVAR group, 136 (30.2%) patients had postoperative complications, which included 45 ischemic (10.0%), 34 wound (7.6%), 22 renal (4.9%), 12 cardiac (2.7%), 8 pulmonary (1.8%), 5 gastrointestinal (1.1%), and 4 neurologic (0.9%) events.

CONCLUSIONS

A relatively higher proportion of women underwent TEVAR than EVAR, and this was reflected in the greater need for iliac conduits to accommodate the larger delivery catheters of the thoracic devices. Intraoperative imaging techniques were also different, and TEVAR required higher contrast volumes despite shorter overall procedure times. The incidence of strokes and spinal cord ischemia was also higher during TEVAR. Despite apparent similarities of devices and techniques, EVAR and TEVAR are fundamentally different procedures with different perioperative outcomes.

Characterization of 75:25 poly(l-lactide-co-epsilon-caprolactone) thin films for the endoluminal delivery of adipose-derived stem cells to abdominal aortic aneurysms

Abdominal aortic aneurysms occur in 5-7% of men over the age of 60 and their incidence is rising. Current therapies remove the affected tissue or prevent blood flow through the aneurysm, but do not repair the underlying structural changes of the vascular wall. Adipose tissue derived stem cells (ADSCs) seeded on a biodegradable thin film and delivered endoluminally to the aneurysm site could potentially repair the vessel wall, preventing growth and rupture of the aneurysm. In this study, the mechanical and degradation properties of a novel 75:25 poly(l-lactide-co-epsilon-caprolactone) (PLCL) thin film, as well as, the effects of different surface structures on stem cell adherence and resistance to shear stress was investigated. It was possible to reproducibly create films of consistent physical properties. These films degraded approximately 50% in 6 month, which would be a sufficient time to allow cells to engraft in the aortic wall. Ethylene oxide treatment significantly increased the stiffness and yield stress of the films, which exhibit >700% elongation. Treatment of the films with NaOH and HCl induced the formation of surface texture on the films; however, this texture did not affect stem cell adherence or resistance to delamination by shear stress when compared to nontreated or fibronectin-coated films. These results indicate that PLCL thin films have a sufficient degradation time and mechanical strength to serve as a scaffold in vivo for ADSCs, and that ADSCs seeded on the thin film can withstand a range of physiologic shear stresses.

Long-term outcomes after endovascular abdominal aortic aneurysm repair: the first decade

OBJECTIVE

The proper role of endovascular abdominal aortic aneurysm repair (EVAR) remains controversial, largely due to uncertain late results. We reviewed a 12-year experience with EVAR to document late outcomes.

METHODS

During the interval January 7, 1994 through December 31, 2005, 873 patients underwent EVAR utilizing 10 different stent graft devices. Primary outcomes examined included operative mortality, aneurysm rupture, aneurysm-related mortality, open surgical conversion, and late survival rates. The incidence of endoleak, migration, aneurysm enlargement, and graft patency was also determined. Finally, the need for reintervention and success of such secondary procedures were evaluated. Kaplan-Meier and multivariate methodology were used for analysis.

RESULTS

Mean patient age was 75.7 years (range, 49-99 years); 81.4% were male. Mean follow-up was 27 months; 39.3% of patients had 2 or more major comorbidities, and 19.5% would be categorized as unfit for open repair. On an intent-to-treat basis, device deployment was successful in 99.3%. Thirty-day mortality was 1.8%. By Kaplan-Meier analysis, freedom from AAA rupture was 97.6% at 5 years and 94% at 9 years. Significant risk factors for late AAA rupture included female gender (odds ratio OR, 6.9; P = 0.004) and device-related endoleak (OR, 16.06; P = 0.009). Aneurysm-related death was avoided in 96.1% of patients, with the need for any reintervention (OR, 5.7 P = 0.006), family history of aneurysmal disease (OR, 9.5; P = 0.075), and renal insufficiency (OR, 7.1; P = 0.003) among its most important predictors. 87 (10%) patients required reintervention, with 92% of such procedures being catheter-based and a success rate of 84%. Significant predictors of reintervention included use of first-generation devices (OR, 1.2; P < 0.01) and late onset endoleak (OR, 64; P < 0.001). Current generation stent grafts correlated with significantly improved outcomes. Cumulative freedom from conversion to open repair was 93.3% at 5 through 9 years, with the need for prior reintervention (OR, 16.7; P = 0.001) its most important predictor. Cumulative survival was 52% at 5 years.

CONCLUSIONS

EVAR using contemporary devices is a safe, effective, and durable method to prevent AAA rupture and aneurysm-related death. Assuming suitable AAA anatomy, these data justify a broad application of EVAR across a wide spectrum of patients.

A new model of abdominal aortic aneurysm with gastric serosa patch: surgical technique and short-term evaluation

The purpose of this work was to develop an abdominal aortic aneurysm (AAA) model that resembles human aneurysms with potential for further growth, patent collateral vessels, and a predictable tendency to rupture, and that can be used in the development of new endoprostheses and implant training. An infrarenal AAA model was created in five domestic swine using an autologous gastric serosal patch. Pre- and postsurgical digital subtraction aortograms (DSA) were obtained to document the appearance and dimensions of the aneurysm. Animals were followed up with DSA and ultrasonography on days 7, 14, 30, 45, 60, and 90 after model creation. Aneurysmal diameters were measured with both techniques in all examinations. On day 90, animals were euthanized, target arteries were harvested, and pathological evaluation was performed. The nonparametric Wilcoxon test was used to assess any differences in measured diameters. All the animals survived the surgical procedure. The aneurysmal diameters increased from 8.14+/- 2.15 to 13.28+/- 1.18 mm immediately after surgery (p < .05), but no subsequent significant growth of the aneurysmal sac was seen during follow-up. In this experimental setting, measurements obtained with DSA were slightly larger than those obtained with ultrasound. Two animals died of AAA rupture on days 6 and 10 (40% rupture rate). Pathological examination showed lack of elastic laminae and increased collagen content in the aortic patch. Thus, model showed a tendency to rupture, but no significant potential for further aneurysmal growth. It might be useful for training in endovascular therapies, but its usefulness for preclinical endovascular device testing is limited by its lack of growth potential.

Open aneurysm repair in elderly patients not candidates for endovascular repair (EVAR): Comparison with patients undergoing EVAR or preferential open repair

The authors reviewed a 2-year experience with abdominal aortic aneurysm (AAA) repair to determine if patients who were excluded from endovascular aneurysm repair (EVAR) because of anatomic criteria (Group III) represented a higher risk for subsequent open aneurysm repair than either patients undergoing EVAR (Group II) or those patients who preferentially underwent open repair (Group I). Between January 2001 and December 2003, 107 patients underwent AAA repair. Open repair was recommended in patients <70 years of age and without significant comorbidities (Group I). There were 35 patients in Group I; 72 patients were evaluated for EVAR; 29 patients underwent EVAR (Group II), and 43 were excluded and underwent open repair (Group III). Exclusion criteria were those recommended by the graft manufacturers. Patients in Group I were significantly younger than those in Groups II and III (p < 0.0001). Gender, incidence of diabetes, and hypertension were similar in all groups. Patients in Group III had a greater incidence of coronary artery disease (CAD) than those in Groups I and II, trending toward statistical significance (p = 0.06). Aneurysm size in Group II was statistically smaller than in Group I or III. Group III had significantly more complications (25.6% vs 5.7% and 6.9%) than either Group I or II (p < 0.015). Cardiac complications were similar in all groups. Three patients in Group III required prolonged intubation and 3 in Group III developed renal insufficiency. A history of CAD was predictive of complications (21.8% vs 5.8%, p < 0.024), as was inclusion in Group III. There were 2 deaths in this series, both in Group III. Length of stay was significantly less in Group II (4.17 +/-2.36 days) than in Group I (6.57 +/-1.84 days) or Group III (12.30 +/-9.82 days) (p = 0.0001). Open aneurysm repair can be safely performed in younger good-risk patients (Group I) with results equivalent to EVAR (Group II) but with slightly longer length of stay (LOS). In older patients with suitable anatomy EVAR can be performed with minimal morbidity and short LOS. Older patients not suitable for EVAR (Group III) constitute a higher risk group of patients because of increased incidence of CAD and the need for more complex repairs. However, the mortality rate in this group was only 4.6%.

Implant Degradation and Poor Healing After Endovascular Repair of Abdominal Aortic Aneurysms: An Analysis of Explanted Stent-Grafts

PURPOSE

To study explanted stent-grafts to achieve a better understanding of the mechanisms of failure after endovascular treatment of abdominal aortic aneurysms (AAA).

METHODS

Twelve stent-grafts were harvested at autopsy (n=3) or during surgical conversion (n=9). Device alterations were investigated by macroscopic examination, radiography, and surface analysis techniques. Healing around the implants was studied via histology and immunohistochemistry, with particular attention to the stent-graft/tissue interface.

RESULTS

Degradation was more important with Vanguard stent-grafts (off the market) than with AneuRx and Talent stent-grafts, but rupture of nitinol wires and poor surface finish in Talent stent-grafts raise concern about their corrosion resistance and long-term stability. Poor healing was observed around stent-grafts even after several years of implantation, with absence of vascular smooth muscle cells, fibroblasts, and collagen formation. In addition to the well-known foreign body reaction around the graft, numerous polymorphonuclear cells characteristic of the first step of healing were present in tissues around stent-grafts retrieved at surgical conversion. Factors explaining the lack of tissue organization around stent-grafts are discussed.

CONCLUSION

The long-term stability of implants remains a concern and requires more transparency from manufacturers regarding the surface properties of their devices. Lack of neointima formation impairs biological fixation of the implant to the vessel wall, leading to possible endoleaks and migration. New-generation stent-grafts promoting biological fixation should be developed to improve clinical outcomes of this minimally invasive treatment.

Influence of anesthesia type on outcome after endovascular aortic aneurysm repair: An analysis based on EUROSTAR data

BACKGROUND

Local and regional anesthesia was used in endovascular aortic aneurysm repair (EVAR) shortly after its introduction, and the feasibility has been documented several times. Nevertheless, locoregional anesthesia has not become accepted on a large scale, probably owing to a traditional surgical attitude preferring general anesthesia. This study compared various anesthesia techniques in patients treated with EVAR for infrarenal aortic aneurysms.

METHODS

From July 1997 to August 2004, 5557 patients who underwent EVAR repair in 164 centers were enrolled in the EUROSTAR registry. Data were compared among three groups: a general anesthesia group (GA-G) of 3848 patients (69%), a regional anesthesia group (RA-G) of 1399 patients (25%), and the local anesthesia group (LA-G) of 310 patients (6%). Differences in preoperative and operative details among the three study groups were analyzed using the chi(2) test for discrete variables and the Kruskal-Wallis test for continuous variables. Multivariate logistic regression analysis was performed on early complications.

RESULTS

The duration of the operation was reduced in the LA-G (115.7 +/- 42.2 minutes) compared with the RA-G (127.6 +/- 52.8 min, P < .0009) and GA-G (133.3 +/- 59.1 minutes, P < .0001). Admission to the intensive care unit was significantly less for LA-G patients (2%) than RA-G (8.3%, P = .0004) and GA-G (16.2%, P < .0001), but RA-G still had a distinct advantage (P < .0001) over GA-G. Hospital stay was significantly shorter in LA-G (3.7 +/- 3.1 days [P < .0001] vs GA-G [P = .007] vs RA-G), but RA-G (5.1 +/- 7.5 days) still had an advantage (P < .0001) vs GA-G (6.2 +/- 8.5 days). In EUROSTAR, systemic complications were significantly lower both for LA-G (6.6%, P = .0015) and RA-G (9.5%, P = .0007) than for GA-G (13.0%).

CONCLUSION

The EUROSTAR data indicate that patients appeared to benefit when a locoregional anesthetic technique was used for EVAR. Locoregional techniques should be used more often to enhance the perioperative advantage of EVAR in treating infrarenal aneurysms of the abdominal aorta.

Endovascular management of isolated iliac artery aneurysms

OBJECTIVE

We reviewed our experience with endovascular treatment of isolated iliac artery aneurysms (IAAs).

METHODS

Medical records for consecutive patients undergoing endovascular IAA repair from 1995 to 2004 were reviewed. Computed tomography (CT) angiograms were used to assess IAA location, size, and presence of endoleaks after endovascular repair. Rates of primary patency and freedom from secondary interventions were estimated using the Kaplan-Meier life-table method.

RESULTS

From July 1995 to November 2004, 45 patients (42 men), with a mean age of 75 years, underwent endovascular repair of 61 isolated IAAs: 41 common iliac, 19 internal iliac, and one external iliac. Five patients (11%) were symptomatic, although none presented with acute rupture. The mean preoperative IAA diameter was 4.2 +/- 1.7 cm. Fifteen patients (33%) had prior open abdominal aortic aneurysm repair. Local or regional anesthesia was used in 28 cases (62%). Thirty-four patients (75%) were treated with unilateral iliac stent-grafts, eight (18%) with bifurcated aortic stent-grafts, and three (7%) with coil embolization alone. Perioperative major complications included one early graft thrombosis that eventually required conversion to open repair and one groin hematoma that required operative evacuation. On follow-up, late complications included one additional graft thrombosis and one late death after amputation. No late ruptures occurred after endovascular repair, with a mean follow-up of 22 months (range, 0 to 60 months). The mean postoperative length of stay was 1.3 +/- 1.0 days. On postoperative CT scans obtained at 1, 6, 12, 24, and 36 months, aneurysm shrinkage was noted in 18%, 29%, 57%, 67%, and 83% of IAAs, respectively, compared with the baseline diameter. One hypogastric aneurysm enlarged in the presence of a later identified type II endoleak. Five endoleaks were noted (4 type II, 1 indeterminate) at 1 month, with four other endoleaks (1 type II, 1 type III, 2 indeterminate) identified on later CT scans. At 2 years, primary patency was 95%, and freedom from secondary interventions was 88%.

CONCLUSIONS

Endovascular repair of isolated IAAs appears safe and effective, with initial results similar to those after endovascular abdominal aortic aneurysm repair.

Aortic wrap as a novel technique of type I endoleak repair

Type I endoleak after endovascular abdominal repair is associated with a high risk of aneurysm expansion and rupture. Though type I endoleak can frequently be managed with endovascular techniques, in this report we describe a patient whose endoleak was refractory to multiple attempts at endovascular repair. The patient ultimately underwent a novel minimally invasive surgical repair with placement of an aortic wrap around the infrarenal aortic neck, successfully abolishing the endoleak.

Randomized EVAR Trials and Advent of Level I Evidence: A Paradigm Shift in Management of Large Abdominal Aortic Aneurysms?

The recent endovascular aneurysm repair (EVAR) 1 and 2 and Dutch Randomized Endovascular Aneurysm Management (DREAM) trials addressed management of abdominal aortic aneurysms (AAAs) larger than 5.5 cm in diameter. The DREAM and EVAR 1 trials randomized patients appropriate for open repair between endovascular repair (EVAR) and open repair (OR), and the EVAR 2 trial randomized patients unfit for OR between EVAR and conservative nonoperative management (No Rx). The EVAR 1 trial showed a 3% lower initial mortality for EVAR, with a persistent reduction in aneurysm-related death at 4 years. Improvement in overall late survival was not demonstrated. Similarly, the DREAM trial observed an initial mortality advantage for EVAR, but overall 1-year survival was equivalent in both groups. Both trials found significantly higher complication and intervention rates and higher hospital costs with EVAR, and by 1 year a quality of life (QOL) benefit was not evident. The EVAR 2 trial did not demonstrate a survival advantage of EVAR with respect to nonoperative management, while noting that EVAR was associated with greater likelihood of treatment complications, subsequent interventions, and threefold higher costs. Both EVAR trials were limited by long delays between randomization and treatment. Moreover, 27% of patients in EVAR 2 crossed over from nonoperative to endovascular repair, and these patients had a lower procedure mortality from EVAR than those originally assigned to it (2% v 9%). These 47 cases, and the exclusion of 14 patients dying while waiting for EVAR, appears to confer a survival advantage to those receiving EVAR over those receiving no treatment in a post-hoc analysis, but per-protocol analysis of the EVAR 2 trial data performed by the EVAR investigators did not show a significant difference in either all-cause or aneurysm-related mortality. Thus, outcomes of the EVAR 2 trial have not settled the choice between EVAR and no treatment in this scenario to everyone's satisfaction. In patients with large AAAs who are fit for OR, EVAR offers an initial mortality advantage over OR, with a persistent reduction in AAA-related death at 4 years. However, EVAR offers no overall survival benefit, is more costly, and requires more interventions and indefinite surveillance with only a brief QOL benefit. It may or may not offer a mortality benefit over nonoperative management in patients with large AAAs who are unfit for open repair, but the statistical significance of this comparison is inconclusive.

Stent-Grafts for Unruptured Abdominal Aortic Aneurysms: Current Status

Aortic stent-grafts were introduced at the beginning of the 1990s as a less invasive method of dealing with aortic aneurysms in patients with poor cardiovascular reserve. The numbers of procedures performed worldwide has increased exponentially despite the current lack of any substantial evidence for long-term efficacy in comparison with the gold standard of open surgical grafting. This review summarizes the evolution of the abdominal aortic stent-graft, the techniques used for assessment and deployment, and the effect of the procedure on both the patient and the device. The recent publication of two national multicenter trials has confirmed that the endovascular technique confers a 2.5-fold reduction in 30-day mortality in comparison with open surgery. However, over 4 years of follow-up, there is a 3-fold increase in the risk of reintervention and the overall costs are 30% greater with endovascular repair. Although the improvement in aneurysm-related mortality persists in the mid-term, because of the initial reduction in perioperative mortality, the all-cause mortality rate at 4 years is actually no better than for open surgery. Longer-term data from the randomized trials are awaited as well as results from the latest trials utilizing state-of-the-art devices. Whilst the overall management of abdominal aortic aneurysms has undoubtedly benefited from the introduction of stent-grafts, open repair currently remains the gold standard treatment.

Endovascular AAA Repair With the Aortomonoiliac EndoFit Stent-Graft: Two Years' Experience

PURPOSE

To evaluate the feasibility and efficacy of a specific aortomonoiliac endograft and the durability of the femorofemoral bypass for treatment of abdominal aortic aneurysm (AAA).

METHODS

From 2002 to 2004, 39 high-risk (ASA III/IV) patients (36 men; median age 74 years, range 63-84) with AAA (n = 33) or AAA and common iliac artery aneurysm (n = 6) were treated with an EndoFit aortomonoiliac endograft and femorofemoral crossover bypass. The contralateral iliac axis was obstructed with an endoluminal occluder. Patients were followed with contrast-enhanced computed tomography at 1, 6, 12, and 24 months.

RESULTS

EndoFit AMI stent-grafts were implanted successfully in all patients. Perioperative mortality was zero. Endoleak occurred in 3 (7.7%) cases. A proximal type I endoleak was identified at 1 month and was treated with a proximal cuff. Two type II endoleaks are under surveillance because the aneurysm sac shows no enlargement. Thrombosis of the femorofemoral graft occurred in 1 case during the immediate postoperative period due to insufficient inflow from a residual stenosis of the endograft (primary patency 97.5%). The deficit was treated successfully (secondary patency 100%). Two (5.1%) tunnel hematomas were treated conventionally. Median follow-up was 14 months (range 6-30). All patients are alive. None of the aneurysms has ruptured or been converted to an open procedure. Graft migration, serious infection, paraplegia, distal embolization, or any other serious complication has not been observed.

CONCLUSIONS

In high surgical risk patients with complex iliac anatomy, aortomonoiliac endograft with femorofemoral crossover bypass is feasible and efficacious. Moreover, the midterm patency of the extra-anatomic bypass appears quite satisfactory.

Early outcomes of endovascular versus open abdominal aortic aneurysm repair in the National Surgical Quality Improvement Program–Private Sector (NSQIP–PS)

BACKGROUND

There remains no consensus on the appropriate application of endovascular abdominal aortic aneurysm repair (EVAR). Information from administrative databases, industry-sponsored trials, and single institutions has inherent deficiencies. This study was designed to compare early outcomes of open (OPEN) versus EVAR in a contemporary (2000 to 2003) large, multicenter prospective cohort.

METHODS

Fourteen academic medical centers contributed data to the National Surgical Quality Improvement Program-Private Sector (NSQIP-PS), which ensures uniform, comprehensive, prospective, and previously validated data entry by trained, independent nurse reviewers. A battery of clinical and demographic features was assessed with multivariate analysis for association with the principal study end points of 30-day operative mortality and morbidity.

RESULTS

One thousand forty-two patients underwent elective infrarenal abdominal aortic aneurysm (AAA) repairs: 460 EVAR and 582 OPEN. EVAR patients were older (74 vs 71 years, P < .0001), included more men (84.6% vs 79.6%, P < .05), and had a higher incidence of chronic obstructive pulmonary disease (25.4% vs 17.9%, P < .01). EVAR resulted in significantly reduced overall morbidity (24% vs 35%, P < .0001) and hospital stay (4 vs 9 days, P < .0001). Cardiopulmonary and renal function-related comorbidities had the expected significant impact on mortality for both procedures at univariate analysis ( P < .05). While crude mortality rates between EVAR and OPEN did not differ significantly (2.8% vs 4.0%) ( P = 0.32). After multivariate analysis, correlates of operative mortality included OPEN (odds ratio [OR], 2.44; 95% confidence interval [CI], 1.03 to 5.78; P < .05), advanced age (OR, 1.11; P < .001), history of angina (OR, 5.54; P < .01), poor functional status (OR, 5.78; P < .001), history of weight loss (OR, 7.42; P < .01), and preoperative dialysis (OR, 51.4; P < .0001). EVAR also compared favorably to OPEN (OR, 2.14; 95% CI, 1.58 to 2.89; P < .0001) for overall morbidity.

CONCLUSION

Significant morbidity accompanies AAA repair, even at major academic medical centers. These data strongly endorse EVAR as the preferred approach in the presence of significant cardiopulmonary or renal comorbidities, or poor preoperative functional status.

Angiotensin II and abdominal aortic aneurysms

Abdominal aortic aneurysms (AAAs) have devastating effects on the morbidity and mortality of a large portion of the elderly population. Current therapeutic options for AAAs are limited to surgical approaches, because there are no proven pharmacologic treatments. Recently, there is evolving evidence that angiotensin II (Ang II) participates in the initiation and propagation of AAAs. Animal studies have consistently demonstrated the ability of Ang II to promote the formation of AAAs, although the mechanisms of this effect have not been defined. Further definition of the role of the renin-angiotensin system in AAA formation and progression will identify potential therapeutic strategies for treatment of this disease.

Overview of success of EVAR: Progress to date

Endovascular aneurysm repair (EVAR) of abdominal aortic aneurysms has been challenged by a number of groups, and the shortcomings of this procedure have been documented in the scientific literature. However, patients and physicians continue to pursue this procedure as a viable means of treating abdominal aortic aneurysms. Both device evolution and advancement of technical skills have led to dramatic improvements in the outcomes of EVAR within the last decade. These improvements and accomplishments have also been chronicled in the literature. This review looks at the successes of EVAR, based on both US Food and Drug Administration trials and independent studies comparing conventional open repair and endovascular repair.

Clinical effect of abdominal aortic aneurysm endografting: 7-year concurrent comparison with open repair

OBJECTIVE

We compared the effectiveness and clinical outcome of open repair versus endovascular aortic aneurysm repair (EVAR) in achieving prevention of abdominal aortic aneurysm (AAA)-related death and graft-related complications.

METHODS

Over 7 years from 1997 to 2003, 1119 consecutive patients underwent elective treatment of infrarenal AAAs, 585 with open repair and 534 with EVAR. Patients were regularly followed up at 1, 6, 12 months, and every 6 months thereafter, in EVAR group, and at 3 and 12 months, and yearly thereafter after open repair. Preoperative, intraoperative, and follow-up data were stored in a prospective database.

RESULTS

Median follow-up was similar in the 2 groups: 33 months (interquartile range [IQR], 13-50 months) in the EVAR group vs 35 months (IQR, 15-54 months) in the open repair group. EVAR group patients were older than patients in the open repair group: 73 years vs 72 years (P = .04). There were statistical significant differences between the EVAR group and the open repair group with respect to AAA median diameter (52 mm vs 56 mm), coronary disease rate (46% vs 37%; P = .001), pulmonary disease rate (56% vs 38%; P < .0001), and American Society of Anesthesiologists IV score rate (16% vs 6%; P < .0001). Thirty-day mortality in the EVAR group was 0.9% (5 of 534 patients), compared with 4.1% (24 of 585 patients; P = .001) in the open repair group, and major morbidity was 9.1% (49 of 534 patients) vs 18.6% (109 of 585 patients; P < .0001), respectively. The incidence of secondary procedures in the EVAR group was 15.7%, compared with 3% in the open repair group (P < .0001). There were no deaths related to secondary procedures in either group. Six AAAs (1.1%) ruptured after EVAR, 3 of which were fatal; in the open repair group 1 patient (0.2%) underwent successful repeat operatation to treat iliac pseudoaneurysm rupture 5 years after the original procedure. Kaplan-Meier estimates for freedom from aneurysm-related death at 84 months were 97.5% in the EVAR group and 95.9% in the open repair group (log rank test, P = .008). Kaplan-Meier survival estimates at 84 months were 67.1% in the open repair group and 66.9% in the EVAR group (P = NS). At the same interval the risk for secondary procedures was 49.4% for the EVAR group and 7.1% for the open repair group. Of the 11 variables analyzed with logistic analysis, open surgery (hazard ratio [HR], 11; 95% confidence interval [CI], 2.5-54.2; P = .002), American Society of Anesthesiologists IV score (HR, 7.1; 95% CI, 2.7-18.8; P = .0001), and age (HR, 1.06; 95% CI, 1.04-1.13; P = .04) were positive independent predictors of perioperative mortality.

CONCLUSION

Our data suggest that at a maximum follow-up of 7 years, patients who undergo EVAR show lower perioperative and late aneurysm-related mortality compared with a younger and substantially healthier group of patients with aneurysms treated with open repair. The higher need for secondary procedures in the endovascular group did not affect superiority of the overall performance of EVAR in the early and late intervals.