Comparison of endovascular aneurysm repair with open repair in patients with abdominal aortic aneurysm (EVAR trial 1), 30-day operative mortality results: randomised controlled trial

Surgery Insight: advances in endovascular repair of abdominal aortic aneurysms

Despite improvements in diagnostic and therapeutic methods and an increased awareness of their clinical significance, abdominal aortic aneurysms (AAAs) continue to be a major source of morbidity and mortality. Endovascular repair of AAAs, initially described in 1990, offers a less-invasive alternative to conventional open repair. The technology and devices used for endovascular repair of AAAs have progressed rapidly and the approach has proven to be safe and effective in short to midterm investigations. Furthermore, several large trials have demonstrated that elective endovascular repair is associated with lower perioperative morbidity and mortality than open repair. The long-term benefits of endovascular repair relative to open repair, however, continue to be studied. In addition to elective repair, the use of endovascular repair for ruptured AAAs has been increasing, and has been shown to be associated with reduced perioperative morbidity and mortality. Advances in endovascular repair of AAAs, including the development of branched and fenestrated grafts and the use of implantable devices to measure aneurysm-sac pressures following stent-graft deployment, have further broadened the application of the technique and have enhanced postoperative monitoring. Despite these advances, endovascular repair of AAAs remains a relatively novel technique, and further long-term data need to be collected.

Endovascular abdominal aortic aneurysm repair

The operative mortality following conventional abdominal aortic aneurysm (AAA) repair has not fallen significantly over the past two decades. Since its inception in 1991, endovascular aneurysm repair (EVAR) has provided an alternative to open AAA repair and perhaps an opportunity to improve operative mortality. Two recent large randomised trials have demonstrated the short and medium term benefit of EVAR over open AAA repair, although data on the long term efficacy of the technique are still lacking. This review aimed at providing an overview of EVAR and a discussion of the potential benefits and current limitations of the technique.

Epidemiological study of the relationship between volume and outcome after abdominal aortic aneurysm surgery in the UK from 2000 to 2005

Background

The aim was to assess the relationship between hospital volume and outcome after abdominal aortic aneurysm (AAA) surgery in the UK.

Methods

Hospital Episode Statistics (2000–2005) were classified as elective, urgent or ruptured AAA repair. Analysis was by modelling of mortality rate, complication rate and length of hospital stay with regard to the annual operative volume, after risk adjustment.

Results

There were 112 545 diagnoses, or repairs, of AAAs, of which 26 822 were infrarenal aneurysms. The mean mortality rate was 7·4, 23·6 and 41·8 per cent for elective, urgent and ruptured AAA repair respectively. Elective AAA repair undertaken at high-volume hospitals showed volume-related improvements in mortality (P < 0·001). Patients were discharged from hospital earlier (P < 0·001). The critical volume threshold was 32 elective AAA repairs per year. For urgent repair, patients at high-volume hospitals had a reduced mortality rate (P = 0·017) with an increased length of stay (P = 0·041). There was no relationship between volume and outcome for ruptured AAA repairs.

Conclusion

Increased annual volumes were associated with significant reductions in mortality for elective and urgent AAA repair, but not for repair of ruptured AAAs.

Results of streamlined regional ambulance transport and subsequent treatment of acute abdominal aortic aneurysms

OBJECTIVE

To describe the triage of patients operated for non-ruptured and ruptured abdominal aortic aneurysms (AAAs) before the endovascular era.

DESIGN

Retrospective single-centre cohort study.

METHODS

All patients treated for an acute AAA between 1998 and 2001 and admitted to our hospital were evaluated in the emergency department for urgent AAA surgery. All time intervals, from the telephone call from the patient to the ambulance department, to the arrival of the patient in the operating theatre, were analysed. Intraoperative, hospital and 1-year survival were determined.

RESULTS

160 patients with an acute AAA were transported to our hospital. Mean (SD) age was 71 (8) years, and 138 (86%) were men. 34 (21%) of these patients had symptomatic, non-ruptured AAA (sAAA) and 126 patients had ruptured AAA (rAAA). All patients with sAAA and 98% of patients with rAAA were operated upon. For the patients with rAAA, median time from telephone call to arrival at the hospital was 43 min (interquartile range 33-53 min) and median time from arrival at the hospital to arrival at the operating room was 25 min (interquartile range 11-50 min). Intraoperative mortality was 0% for sAAA and 11% for rAAA (p = 0.042), and hospital mortality was 12% and 33%, respectively (p = 0.014).

CONCLUSIONS

A multidisciplinary unified strategy resulted in a rapid throughput of patients with acute AAA. Rapid transport, diagnosis and surgery resulted in favourable hospital mortality. Despite the fact that nearly all the patients were operated upon, survival was favourable compared with published data.

Intraobserver and interobserver variability of 64-row computed tomography abdominal aortic aneurysm neck measurements

BACKGROUND

Integrity of the abdominal aortic aneurysm (AAA) neck is crucial for the long-term success of endovascular AAA repair (EVAR). However, suitable tools for reliable assessment of changes in small aortic volumes are lacking. The purpose of this study was to assess the intraobserver and interobserver variability of software-enhanced 64-row computed tomographic angiography (CTA) AAA neck volume measurements in patients after EVAR.

METHODS

A total of 25 consecutive patients successfully treated by EVAR underwent 64-row follow-up CTA in 1.5-mm collimation. Manual CTA measurements were performed twice by three blinded and independent readers in random order with at least a 4-week interval between readings. Maximum and minimum transverse aortic neck diameters were measured twice on two different levels within the proximal neck. Volumetry of the proximal aortic neck was performed by using dedicated software. Variability was calculated as 1.96 SD of the mean arithmetic difference according to Bland and Altman. Two-sided and paired t tests were used to compare measurements. P values <.05 were considered to indicate statistical significance.

RESULTS

Intraobserver agreement was excellent for dedicated aneurysmal neck volumetry, with mean differences of less than 1 mL (P > .05), whereas it was poor for transverse aortic neck diameter measurements (P < .05). However, interobserver variability was statistically significant for both neck volumetry (P < .005) and neck diameter measurements (P < .015).

CONCLUSIONS

The reliability of dedicated AAA neck volumetry by using 64-row CTA is excellent for serial measurements by individual readers, but not between different readers. Therefore, studies should be performed with aortic neck volumetry by a single experienced reader.

Large infra-renal abdominal aortic aneurysms: endovascular vs. open repair--single centre experience

Endovascular aneurysm repair (EVAR) has become an established alternative to open repair (OR). We present a consecutive series of 486 elective patients with large infra-renal aortic abdominal aneurysm, comparing OR with EVAR. Prospective data collected during an 8-year period from January 1997 to October 2005 was reviewed. Statistical analysis performed using SPSS data editor with chi(2) tests and Mann-Whitney U-tests. There were 486 patients with 329 OR (293 males, 36 females) with median age of 72 years with median diameter 6.3 cm and 157 EVAR (148 males, 9 females) with median age 75 years with median diameter 6.1 cm. Mortality was 13 (4%) for OR and 5 (3.2%) for EVAR (three of whom were in the UK EVAR 2 trial). Blood loss was significantly less for EVAR 500 ml vs. 1500 ml for OR. Sixty-five (19.8%) patients with OR had significantly more peri-operative complications compared with 14 (8.9%) with EVAR. The length of stay in hospital was significantly less for EVAR. This non-randomised study shows that although EVAR does not have a statistically significantly lower mortality, it does have statistically significantly lower complication rates compared with OR. EVAR can be achieved with good primary success, but long-term follow-up is essential to assess durability.

Long-term outcome and reintervention after endovascular abdominal aortic aneurysm repair using the Zenith stent graft

OBJECTIVE

To assess the long-term performance of the bifurcated Zenith stent graft.

METHODS

A total of 325 patients (300 men and 25 women) underwent elective endovascular abdominal aortic aneurysm repair with bifurcated Zenith stent grafts between October 1998 and December 2005. Follow-up included routine contrast-enhanced computed tomography and multiview abdominal radiographs at 1, 6, and 12 months and yearly thereafter. Data on late-occurring (>30 days after stent-graft implantation) complications and interventions were collected prospectively.

RESULTS

Of the original 325 patients, 92 have since died, resulting in a mean follow-up of 2.3 years (range, 1 month to 7.0 years). Nine (2.8%) of 325 patients required reintervention to treat or prevent endoleak (type I or III) or graft occlusion at an average of 1.4 years after stent-graft placement (range, 40 days to 4.0 years). Three (0.9%) of these patients died from causes related to malfunction of the stent graft: one each from aneurysm rupture, stent-graft infection, and infection of a femoral-femoral bypass graft placed after limb occlusion. Nineteen additional patients (5.8%) required treatment for type II endoleak, for a total reintervention rate of 8.6%.

CONCLUSIONS

Late failures of Zenith stent-graft attachment, structure, or function are rare. In the absence of known endoleak, routine follow-up imaging plays a limited role in the identification and prevention of impending failure.

The outcome of endovascular repair of small abdominal aortic aneurysms

OBJECTIVE

To assess the outcome of endovascular repair (EVAR) of small abdominal aortic aneurysms (AAA, <or=5.5 mm maximum diameter) in Australia.

SUMMARY BACKGROUND DATA

Randomized trials have suggested that small AAAs should not be treated by open surgery. EVAR is associated with less perioperative mortality than open surgery for large AAAs. We assessed the outcome of EVAR of small AAAs as part of a national audit.

METHODS

ASERNIP-S carried out a prospective audit of EVAR performed between November 1999 and May 2001 in Australia. A total of 478 of the 961 patients entered underwent treatment of a small AAA. Data were collected regarding preoperative characteristics, procedural outcome, and intermediate success. Median follow-up was 3.2 years. Data were analyzed using Kaplan-Meier and Cox proportional hazard analyses.

RESULTS

The 30-day mortality and technical success rates were 1.1% and 98%, respectively. Postoperative complications occurred in 29%. Survival was 84% and 52% at 3 and 5 years, respectively. Primary, assisted primary, and secondary clinical success rates were 72%, 79%, and 82%, respectively, at 3 years. Reintervention rate was 11% at 3 years; however, 15% of patients continued to have significant aortic sac enlargement. Survival was reduced in patients considered unfit for general anesthesia (odds ratio = 2.6; 95% confidence interval, 1.4-4.8, P = 0.002) or those who had elevated preoperative serum creatinine (odds ratio = 2.0; 95% confidence interval, 1.3-3.0, P = 0.001).

CONCLUSIONS

EVAR can be carried with good perioperative outcome in patients with small AAA; however, intermediate success is hampered by the need for reintervention and continued aortic sac enlargement. At present, widespread treatment of small AAAs by EVAR would appear inappropriate.

Should usual criteria for intervention in abdominal aortic aneurysms be "downsized," considering reported risk reduction with endovascular repair?

Two randomized trials have demonstrated the safety of waiting until abdominal aortic aneurysm (AAA) diameter reaches 5.5 cm for repair in most patients. Other recent randomized trials have demonstrated lower perioperative mortality and morbidity with endovascular aneurysm repair (EVAR) compared to open surgery. Therefore, it is logical to assume that endovascular repair may change the appropriate threshold for intervention. However, endovascular repair is not as durable as open surgery and is associated with ongoing risks of rupture and reintervention. Decision analysis based on data available in 1998 showed that endovascular repair should not change the threshold for intervention. Since that time retrospective data have emerged to suggest that outcomes with endovascular repair are improved in smaller AAAs, although this may simply represent selection bias and the natural history of small AAAs. Randomized trials are appropriate to determine whether improved endovascular outcomes in small AAAs reduce late rupture and reintervention enough to justify early intervention in patients with appropriate anatomy. In the absence of data from these trials, the threshold for intervention should not be changed.

Influence of Severe Infrarenal Aortic Neck Angulation on Complications at the Proximal Neck Following Endovascular AAA Repair: A EUROSTAR Study

PURPOSE

To examine the influence of severe infrarenal neck angulation (SNA) on complications after endovascular repair of abdominal aortic aneurysm (AAA).

METHODS

From October 1996 to January 2006, 5183 patients who underwent endovascular aneurysm repair using a Talent, Zenith, or Excluder stent-graft were enrolled into the EUROSTAR registry. Incidence of proximal type I endoleak, stent-graft migration, proximal neck dilatation, aneurysm rupture, secondary interventions, and all-cause and aneurysm-related mortality were compared between patients with and without severe infrarenal neck angulation (>60 degrees angle between the infrarenal aortic neck and the longitudinal axis of the aneurysm).

RESULTS

In the short term (before discharge), proximal type I endoleak (OR 2.32, 95% CI 1.60 to 3.37, p<0.0001) and stent-graft migration (OR 2.17, 95% CI 1.20 to 3.91, p=0.0105) were observed more frequently in patients with SNA. Over the long term, higher incidences of proximal neck dilatation > or =4 mm (HR 1.26, 95% CI 1.11 to 1.43, p=0.0004), proximal type I endoleak (HR 1.80, 95% CI 1.25 to 2.58, p=0.0016), and need for secondary interventions (HR 1.29, 95% CI 1.00 to 1.67, p=0.0488) were seen in patients with SNA. All-cause mortality, aneurysm-related mortality, and rupture of the aneurysm were similar in patients with and without severe neck angulation. In the subgroup of patients with an Excluder endograft, proximal endoleak at the completion angiogram (OR 4.49, 95% CI 1.31 to 15.32, p=0.0166) and long-term proximal neck dilatation (HR 1.67, 95% CI 1.20 to 2.33, p=0.0026) were more frequently observed in patients with SNA. In the Zenith subgroup, proximal endoleak at the completion angiogram (OR 2.62, 95% CI 1.49 to 4.63, p=0.0009) and proximal stent-graft migration before discharge (OR 2.34, 95% CI 1.06 to 5.19, p=0.0353) were more common in patients with SNA. In the Talent subgroup, long-term proximal endoleak (HR 2.09, 95% CI 1.27 to 3.44, p=0.0036), proximal neck dilatation (HR 1.29, 95% CI 1.05 to 1.60, p=0.0168), and secondary interventions (HR 1.54, 95% CI 1.05 to 2.24, p=0.0259) were more frequently observed in patients with SNA.

CONCLUSION

Severe infrarenal aortic neck angulation was clearly associated with proximal type I endoleak, while the relationship with stent-graft migration was not clear. Excluder, Zenith, and Talent stent-grafts perform well in patients with severe neck angulation, with only a few differences among devices.

Elective treatment of abdominal aortic aneurysm with endovascular or open repair: The first decade

OBJECTIVES

The development of endovascular aneurysm repair (EVAR) as an alternative to open repair of abdominal aortic aneurysms (AAA) has led to an increasing number of patients being treated by this less-invasive technique. It was anticipated that EVAR would reduce the operative mortality and morbidity compared with open repair. This study examined the initial 10-year experience in one center when both techniques were available to determine if there were advantages to one technique or the other, putting the results into the perspective of routine clinical care of patients with infrarenal AAA.

METHODS

From June 1996 to May 2005, 677 patients underwent elective repair of their infrarenal AAA, of which 417 were treated with open repair and 260 by EVAR. Demographic and aneurysm-specific data, comorbidities, operative morbidity, mortality, and late outcome were analyzed.

RESULTS

Open repair patients were 2 years younger (71 vs 74 years, P < .001), had larger aneurysms (6.01 +/- 1.38 cm vs 5.45 +/- 0.99 cm, P < .001), greater familial predisposition, a higher incidence of current smokers, and a higher incidence of chronic obstructive pulmonary disease than the EVAR group. There were no differences in renal function, hypertension, coronary artery disease, or heart failure between the two groups. Overall operative mortality was 3.1%; operative mortality per group was 3.5% for open and 2.7% for EVAR (P = .627). Procedure-related outcomes showed significant differences in operative blood loss and length of hospital stay in favor of EVAR, and 95% of the EVAR patients were discharged home vs 83% in the open repair group (P < .001). A Kaplan-Meier log-rank analysis showed no difference in early or long-term survival between open repair and EVAR (P = .20), but did show a difference in mid-term (3-year) survival favoring open repair (P < .002). Survival analysis by age (<70 and > or =70 years) showed no difference between treatment groups.

CONCLUSIONS

Open repair and EVAR are both performed safely in patients treated for elective infrarenal AAA. EVAR has the perioperative advantages of reduced blood loss, reduced length of intensive care unit and hospital stay, and increased number of patients discharged to home. The mid-term survival advantage of open repair has been observed in other reports and deserves further study.

Treatment of Infrarenal Abdominal Aortic Aneurysms With Oversized (36-mm) Zenith Endografts

PURPOSE

To evaluate the outcome of treating infrarenal abdominal aortic aneurysms with unfavorable necks using the 36-mm Zenith endograft.

METHODS

The indication for use of the 36-mm endograft for infrarenal aortic aneurysm was a minimum 20-mm-long sealing zone and a diameter >28 mm at any point but <34 mm, varying more than 3 mm in contour. A series of 67 patients (64 men; mean age 76.2 years, range 59.5 to 88.3) who had been treated with the 36-mm endografts between June 1999 and February 2004 were assessed for medium-term outcomes. The patients were identified from the device planning records. Follow-up was carried out using chart review and direct patient contact. The indication for use of the endograft was checked with the aneurysm neck profile from the original planning diagrams. Cause of death was ascertained from the treating clinician, the medical record, or the State Death Registry. Outcome endpoints were proximal type I and type III endoleaks, migration, sac size change, and death.

RESULTS

The mean diameter of the sealing zone was 31.9+/-1.6 mm within the 20-mm segment from the lowest renal artery. Stent-graft delivery was achieved in all 67 patients. Two (3%) patients died within 30 days from non-graft-related cardiorespiratory causes. Proximal type I endoleaks were identified in 3 (4.5%) patients: 2 during deployment and another at 9 days. The mean follow-up period for the 65 patients who survived 30 days was 26.9+/-12.6 months (range 2-66). Migration occurred in 1 patient with development of a type III endoleak and sac reperfusion due to separation of the graft body from the bare anchor stent owing to suture breakage. Forty-seven patients were alive at the last review. The aneurysm sac had contracted or was unchanged in 45 (96%) cases. Minor enlargements of the sac were observed in 2 patients. The re-intervention rate was 16.4% (11 patients). There was 1 conversion to open repair to treat perigraft sepsis. The aneurysm- and procedure-related mortality was 4.5%; no patient experienced rupture. All-cause mortality was 29.9% (20/67).

CONCLUSION

Large caliber endografts such as the Zenith 36-mm are an alternative option to open surgery or fenestrated endografting for some infrarenal aneurysms.

Initial Observations of Endovascular Aneurysm Repair Using Dyna-CT

PURPOSE

To examine the feasibility of a new technology that provides images resembling computed tomographic (CT) slices on the operating table during elective endovascular abdominal aortic aneurysm (AAA) repair (EVAR).

TECHNIQUE

Commercially available Dyna-CT equipment was used in conjunction with Voxar 3D software for image reconstruction. During the preliminary evaluation of 9 patients (7 men; median age 73 years, range 67-84) with non-ruptured AAA undergoing elective EVAR with the Zenith Trifab stent-graft under regional anesthesia, the equipment functioned sufficiently well to produce the planned image dataset in 8 of 9 patients. Rotation failed in 1 overweight individual due to a short distance between the patient's abdomen and the C-arm. In 7 of 8 patients, the radiologist was able to measure the diameter of the aneurysm, and it was possible to visualize the entire length of the treated aorta and the iliac arteries in all cases. The proximal aortic neck, including the stent-graft, was visualized in 7 cases. No endoleak or other complications was detected, which was confirmed on the pre-discharge CT scans. The time interval from the rotation of the C-arm until the appearance on the monitor of the first automatically generated 3D images was 7 minutes, which has subsequently been reduced to approximately 2 minutes.

CONCLUSION

Our preliminary experience with Dyna-CT is promising, but further research is necessary to define the place of this imaging modality in EVAR.

Performance of endovascular aortic aneurysm repair in high-risk patients: Results from the Veterans Affairs National Surgical Quality Improvement Program

OBJECTIVE

Recent results after endovascular abdominal aortic aneurysm repair (EVAR) have brought into question its value in patients deemed at high-risk for surgical intervention. The Department of Veteran Affairs (VA) National Surgical Quality Improvement Program (NSQIP) is the largest prospectively collected and validated United States surgical database representing current clinical practice. The purpose of our study was to evaluate outcomes after elective EVAR performed in high-risk veterans.

METHODS

Using NSQIP data from 123 participating VA hospitals, we retrospectively evaluated patients who underwent elective aneurysm repair from May 2001 to December 2004. High-risk criteria were used to identify a cohort for analysis (EVAR, n = 788; open, n = 1580). High-risk criteria analyzed included age > or =60 years, American Society of Anesthesiology (ASA) classification 3 or 4, and the comorbidity variables of history of cardiac, respiratory, or hepatic disease, cardiac revascularization, renal insufficiency, and low serum albumin level. Our primary end points were 30-day and 1-year all-cause mortality, and we evaluated a secondary end point of perioperative complications. Statistical analysis included univariate analysis and multivariate modeling.

RESULTS

Veterans who were classified as high-risk underwent elective EVAR with significantly lower 30-day (3.4% vs 5.2%, P = .047) and 1-year all-cause mortality (9.5% vs 12.4%, P = .038) than patients having open repair. EVAR was associated with a decrease in 30-day postoperative mortality (adjusted odds ratio [OR], 0.65; 95% confidence interval [CI], 0.42 to 1.03; P = .067) as well as 1-year mortality (adjusted OR, 0.68; 95% CI, 0.51 to 0.91; P = .0094) despite the presence of severe comorbid conditions. The risk of perioperative complications was significantly lower after EVAR (16.2% vs 31.0%; P < .0001; adjusted OR, 0.41; 95% CI, 0.33 to 0.52; P < .0001). A subset analysis of higher-risk patients (ASA 4 and the above comorbidity variables) still demonstrated an acceptable 30-day mortality rate.

CONCLUSION

In veterans deemed high-risk for surgical therapy, outcomes after elective EVAR are excellent, and the procedure is relatively safe in this special patient population. Our retrospective data demonstrate that patients with considerable medical comorbidities and infrarenal abdominal aortic aneurysms benefit from and should be considered for primary EVAR.

Nitrogen-rich coatings for promoting healing around stent-grafts after endovascular aneurysm repair

Complications following endovascular aneurysm repair (EVAR) are related to deficient healing around the stent-graft (SG). New generations of SG with surface properties that foster vascular repair could overcome this limitation. Our goal was to evaluate the potential of a new nitrogen-rich plasma-polymerised biomaterial, designated PPE:N, as an external coating for polyethylene terephtalate (PET)- or polytetrafluoro-ethylene (PTFE)-based SGs, to promote healing around the implant. Thin PPE:N coatings were deposited on PET and PTFE films. Then, adhesion, growth, migration and resistance to apoptosis of vascular smooth muscle cells (VSMCs) and fibroblasts, as well as myofibroblast differentiation, were assessed in vitro. In another experimental group, chondroitin sulphate (CS), a newly described mediator of vascular repair, was added to normal culture medium, to search for possible additional benefit. PPE:N-coatings, especially on PET, increased and accelerated cell adhesion and growth, compared with control PET and with standard polystyrene culture plates (PCP). PPE:N was also found to increase the resistance to apoptosis in VSMC, an important finding as aneurysms are characterised by VMSC depletion caused by a pro-apoptotic phenotype. Addition of CS in solution further increased migration and resistance to apoptosis. In conclusion, PPE:N-coating and/or CS could promote vascular repair around SGs following EVAR.

Endovascular treatment for ruptured abdominal aortic aneurysm

BACKGROUND

An abdominal aortic aneurysm (AAA) (the pathological enlargement of the aorta) can develop in both men and women as they grow older. It is most commonly seen in men over the age of 65 years. Progressive aneurysm enlargement can lead to rupture and massive internal bleeding, a fatal event unless timely repair can be achieved. Despite improvements in perioperative care, mortality remains high (approximately 50%) after conventional open surgical repair. A newer minimally invasive technique, endovascular repair, has been shown to reduce early morbidity and mortality, as compared to conventional open surgery, for planned AAA repair. Emergency endovascular repair (eEVAR) has been used successfully to treat ruptured abdominal aortic aneurysm (RAAA), proving that it is feasible in selected patients. However, it is not yet known if eEVAR will lead to significant improvements in outcomes for these patients or indeed if it can replace conventional open repair as the preferred treatment for this lethal condition.

OBJECTIVES

To compare the advantages and disadvantages of eEVAR in comparison with conventional open surgical repair for the treatment of RAAA.

SEARCH STRATEGY

The Cochrane Peripheral Vascular Diseases Group searched their trials register (last searched October 2006) and the Cochrane Central Register of Controlled Trials (CENTRAL) database (last searched Issue 4, 2006). We searched a number of electronic databases and handsearched relevant journals until March 2006 to identify studies for inclusion.

SELECTION CRITERIA

Randomised controlled trials in which patients with a confirmed ruptured abdominal aortic aneurysm were randomly allocated to eEVAR, or conventional open surgical repair.

DATA COLLECTION AND ANALYSIS

Studies identified for potential inclusion were independently assessed for eligibility by at least two reviewers, with excluded studies further checked by the agreed arbitrators. As no randomised controlled trials were identified at present no tests of heterogeneity or sensitivity analysis were performed.

MAIN RESULTS

There were no randomised controlled trials identified at present comparing eEVAR with conventional open surgical repair for the treatment of RAAA.

AUTHORS' CONCLUSIONS

There is no high quality evidence to support the use of eEVAR in the treatment of RAAA. However, evidence from prospective controlled studies without randomisation, prospective studies, and retrospective case series suggest that eEVAR is feasible in selected patients, with outcomes comparable to best conventional open surgical repair for the treatment of RAAA . Furthermore, endovascular repair in selected patients may be associated with a trend towards reductions in blood loss, duration of intensive care treatment, and mortality.

The influence of aortic cuffs and iliac limb extensions on the outcome of endovascular abdominal aortic aneurysm repair

BACKGROUND

In a proportion of patients with an endovascular abdominal aortic aneurysm repair (EVAR), aortic cuffs or iliac graft limb extensions are required to enhance sealing or to fix the position of the device. This requirement arises when these goals are not primarily obtained with the basic stent-graft configuration. The aim of this study was to assess the influence of the use of endograft extensions during the primary EVAR procedure on the short- and long-term outcome.

METHODS

The study was based on the data of the EUROSTAR registry. Patient and anatomic characteristics, data regarding the procedure, postoperative complications, and the mortality of patients undergoing EVAR were retrieved from the database. Patients were divided into three groups: (1) no extensions, (2) proximal aortic cuffs, and (3) iliac limb extensions. Logistic regression and Cox proportional hazards models were used to compare significant influences of the use of cuffs or extensions on different outcomes relative to control patients, adjusted for patient and anatomic factors.

RESULTS

The overall cohort comprised 6668 patients: 4932 (74.0%) without extensions, 259 (3.9%) with an aortic cuff, and 1477 (22.2%) with an iliac endograft extension. Both the 30-day (2.3%-3.9%) and the all-cause mortality rates (23%-27% at 4 years) were similar in the three study groups. The use of proximal cuffs or iliac extensions did not have an effect on the incidence of endoleaks of any type (24%-32% at 4 years). The incidences of device kinking (P = .0344) and secondary transfemoral interventions (P = .0053) during follow-up were increased in patients in whom iliac limb extensions were used. In patients with aortic cuffs, no significant associations with altered outcome were observed.

CONCLUSIONS

The use of iliac graft limb extensions at EVAR was associated with a higher incidence of kinking and secondary transfemoral interventions, whereas proximal aortic cuffs did not influence outcome.

Current trends in the management of small abdominal aortic aneurysms

Over the past decade, there have been revolutionary changes in the diagnosis and treatment of abdominal aortic aneurysms. Minimally invasive endovascular technologies have decreased length of stay and, more importantly, improved at least the early outcomes compared with conventional open surgical therapy. Several large, randomized, prospective trials have re-evaluated the optimal size to treat abdominal aortic aneurysms. The guidelines and conclusions from these studies, the UK Small Aneurysm Trial and The Veterans Affairs Administration aneurysm Detection And Management Trial recommend intervening on aortic aneurysms when they reach 5.5 cm in transverse diameter. However, these studies do not bear direct relevance to contemporary management of aneurysms with endovascular techniques. Clinical trials are currently underway to assess the optimal size for treating abdominal aortic aneurysms with endovascular stent grafts.

Pathology, natural history and treatment of abdominal aortic aneurysms

With increasing age of the population and improvement of diagnostic tools, the incidence of abdominal aortic aneurysms (AAA) has been rising steadily. Despite an improvement in operative and interventional treatment options, AAA is the cause of death in 1-3% of men over 65 years of age in industrial countries, mostly due to rupture [1]. Therefore, routine screening for AAA by ultrasonography has been postulated in the past: a 60 year old man with an abdominal aortic diameter of less than 3 cm has a life-time risk of developing AAA close to zero. However, routine screening has not been found to be cost effective. Despite of the results of two well-designed studies, the limits of AAA qualifying the patient for surgery or intervention in contrast to conservative treatment is still a matter of debate. The present review article summarizes the current knowledge of the pathology, incidence, risks, natural course as well as symptoms and current treatment strategies of AAA on the basis of the recent literature.

Contemporary management of the infra-renal abdominal aortic aneurysm

Abdominal aortic aneurysms (AAAs) principally affect men over 60 years of age. Aneurysms are usually asymptomatic and detected coincidentally or following the onset of symptoms. Elective repair of an AAA is considered when the diameter reaches 5.5cm or annual expansion exceeds 1 cm. Rupture represents a catastrophic event and carries an unacceptably high mortality. The advent of endovascular repair heralds an improvement in operative outcome for this disease process. In this review we provide an overview of the recent trials investigating the management of non-ruptured and ruptured aneurysms and the strategies that may be invoked to lower the mortality of this disease process

Review of Interventional Repair for Abdominal Aortic Aneurysm

Abdominal aortic aneurysm is associated with high mortality rate. For over 50 years, open surgical repair was the standard approach for large aneurysms. However, over the past decade, endovascular aneurysm repair (EVAR) has emerged as a viable alternative. EVAR is associated with lower operative and short-term morbidity and mortality and similar long-term survival (up to 4 years) compared with surgical repair. Endoleak remains a significant limitation associated with aneurysm expansion and reintervention. With newer, more versatile endograft designs, improvements in durability, and better surveillance techniques, the utilization of EVAR is likely to continue to expand.

From Innumeracy to Insight: The Uncertainty of Help versus Harm in Treatment of Asymptomatic Aortic Aneurysms

There is insufficient evidence that the surgical treatment of asymptomatic infrarenal aneurysms > 5.5 cm. is beneficial to patients. This is the result of serious complications of aneurysm surgery and the dearth of information from randomized trials. Based on evidence from the literature we defined scenarios and translated data into natural frequency trees to improve understanding of the uncertainty of help versus harm due to treatment of aneurysms. Our analysis shows that the majority of patients can expect little on longevity from surgery while they are at risk of dying from surgery or suffering from serious morbidity. We conclude that, as long as uncertainty persist, patients should be treated in hospitals that can show very low surgical mortality and major morbidity rates. To further resolve the problem of uncertainty randomized trials for larger aneurysms should be performed. Important issues to discuss are the lower and upper limits of the diameter of the aneurysms and the age and risk profiles of the patients to be included in such trials.

Short to Midterm Outcomes of Fenestrated Endovascular Grafts in the Treatment of Abdominal Aortic Aneurysms:A Systematic Review

PURPOSE

To perform a systematic review of the short to midterm outcomes of fenestrated endovascular grafts in patients with abdominal aortic aneurysms (AAA).

METHODS

A search of PubMed and Medline databases for English-language literature was performed to find studies published between 1999 and 2006. Studies investigating the short to midterm results of fenestrated endovascular grafts for AAA were analyzed for clinical outcomes and postprocedural complications.

RESULTS

Nineteen studies involving fenestrated endovascular grafting were retrieved, and 6 of them met criteria for inclusion in the analysis. The remaining studies were excluded because they dealt with technical or case reports or cumulative addition of previous cases. Pooled estimates (95% confidence interval) of postprocedural complications were 1.1% (0.4%-2.7%) for 30-day mortality; 8.3% (2.9%-13.6%) for late mortality; 97% (92%-100%) and 90% (85%-95%) for perfusion of fenestrated vessels at perioperative and late follow-up, respectively; 13.3% (4.1%-22.5%) for postprocedural renal dysfunction; and 11.2% (3.2%-22.5%) and 9.4% (2.6%-16.3%) for early and late endoleak, respectively. There was correlation between preoperative renal insufficiency and postprocedural renal dysfunction, although this was not a statistically significant difference (p=0.2).

CONCLUSION

Our systematic review showed that fenestrated endovascular grafting provides an alternative technique to treat patients with complex aneurysm necks, achieving lower mortality than open repair under comparable conditions. Preoperative renal impairment is a strong indicator of postoperative renal dysfunction. Long-term stability and patency of the fenestrated vessels deserves to be validated.

Abdominal Aortic Aneurysm: Can the Arterial Phase at CT Evaluation after Endovascular Repair Be Eliminated to Reduce Radiation Dose?

PURPOSE

To retrospectively determine if arterial phase computed tomographic (CT) imaging is necessary for follow-up imaging of patients who have undergone endovascular stent-graft therapy for abdominal aortic aneurysm.

MATERIALS AND METHODS

This HIPAA-compliant study was exempt from institutional review board approval; informed patient consent was waived. Eighty-five patients (66 men, 19 women; mean age, 66 years; range, 45-81 years) underwent 110 multidetector CT examinations after endovascular repair of abdominal aortic aneurysms. Nonenhanced CT images were obtained. Intravenous contrast material was then injected at 4 mL/sec, and arterial and venous phase (60 seconds) CT images were obtained. The nonenhanced and venous phase images were evaluated to determine if an endoleak was present. Subsequently, arterial phase images were analyzed. The effective dose was calculated. Ninety-five percent confidence intervals as indicators of how often arterial phase imaging would contribute to the diagnosis of endoleak were determined.

RESULTS

Twenty-eight type II endoleaks were detected by using combined nonenhanced and venous phase acquisitions. Twenty-five of the 28 endoleaks were also visualized during the arterial phase. Three type II endoleaks were seen only during the venous phase. The arterial phase images depicted no additional endoleaks. Seventy-eight CT examinations performed in 67 patients revealed no endoleak during the venous phase. The arterial phase images also depicted no endoleaks at these examinations. Thus, for no more than 3.1% of all examinations, there was 95% confidence that arterial phase imaging would depict an endoleak missed at venous phase imaging. Arterial phase imaging contributed to a mean of 36.5% of the effective dose delivered.

CONCLUSION

Study results indicate that arterial phase imaging may not be necessary for the routine detection of endoleaks. Radiation exposure can be decreased by eliminating this phase.

Effect of challenging neck anatomy on mid-term migration rates in AneuRx endografts

OBJECTIVE

To establish the effect of challenging neck anatomy on the mid- and long-term incidence of migration with the AneuRx bifurcated device in patients treated after Food and Drug Administration approval and to identify the predictive factors for device migration.

METHODS

Prospectively maintained databases at the University of North Carolina (UNC) and Washington University (WU) were used to identify 595 patients (UNC, n = 230; WU, n = 365) who underwent endovascular repair of an infrarenal abdominal aortic aneurysm with the AneuRx bifurcated stent graft. Those patients with at least 30 months of follow-up were identified and underwent further assessment of migration (UNC, n = 25; WU, n = 59) by use of multiplanar reconstructed computed tomographic scans.

RESULTS

Eighty-four patients with a mean follow-up time of 40.3 months (range, 30-55 months) were studied. Seventy percent of the patients (n = 59) met all inclusion criteria for neck anatomy (length, angle, diameter, and quality) as defined by the revised instructions for use guidelines and are referred to as those with favorable neck anatomy (FNA). The remaining 25 patients retrospectively fell outside of the revised instructions for use guidelines and are referred to as those with unfavorable neck anatomy (UFNA). Life-table analysis for FNA patients at 2 and 4 years revealed a migration rate of 0% and 6.1%, respectively. For UFNA patients, it was 24.0% and 42.1% at 2 and 4 years, respectively (P < .0001). The overall (FNA and UFNA) migration rate was 7.1% and 17.1% at 2 and 4 years, respectively. Overall, late graft-related complications occurred in 38% of patients (FNA, 27%; UFNA, 64%; P = .003; relative risk, 1.7). There was no incidence of late rupture or open conversion. The relative risk of migration for UFNA patients was 2.5 compared with FNA patients (P = .0003). A larger neck angle and a longer initial graft to renal artery distance were predictors of migration, whereas shorter neck length approached but did not reach statistical significance.

CONCLUSIONS

Patients who have unfavorable aneurysm neck anatomy experience significantly higher migration, device-related complication, and secondary intervention rates. However, there was no incidence of open conversion, rupture, or abdominal aortic aneurysm-related death, thereby supporting the AneuRx device as a feasible alternative to open repair even in patients with challenging neck characteristics. Enhanced surveillance should be used in these high-risk patients.

HLA-DR expression on monocytes and systemic inflammation in patients with ruptured abdominal aortic aneurysms

Introduction

Mortality from ruptured abdominal aortic aneurysms (RAAA) remains high. Severe systemic inflammation, leading to multi-organ failure, often occurs in these patients. In this study we describe the level of HLA-DR expression in a consecutive group of patients following surgery for RAAA and compare results between survivors and non-survivors. A similar comparison is made for IL-6 and IL-10 levels and Sequential Organ Failure Assessment (SOFA) scores.

Methods

This is a prospective observational study. Patients with RAAA were prospectively analysed. Blood samples were collected on days 1, 3, 5, 7, 10 and 14. The fraction of CD-14 positive monocytes expressing HLA-DR was measured by flow-cytometry. IL-6 and IL-10 levels were measured by ELISA.

Results

The study included 30 patients with a median age of 70 years, of which 27 (90%) were men. Six patients died from multiple organ failure, all other patients survived. The SOFA scores were significantly higher in non-survivors on days 1 through 14. HLA-DR expression on monocytes was significantly lower on days 3, 5, 7, 10 and 14 in non-survivors. IL-6 and IL-10 levels were significantly higher in non-survivors on day 1 and days 1 and 3, respectively.

Conclusion

HLA-DR expression on monocytes was decreased, especially in non-survivors. All patients with RAAA displayed a severe inflammatory and anti-inflammatory response with an increased production of IL-6 and IL-10. Poor outcome is associated with high levels of IL-6 and IL-10 and a high SOFA score in the first three days after surgery, while low levels of HLA-DR expression are observed from day three after RAAA repair.

The Mid-term Effect of Bare Metal Suprarenal Fixation on Renal Function Following Endovascular Abdominal Aortic Aneurysm Repair

OBJECTIVE

The aim of this study was to assess the mid term effect of proximal bare metal fixation design on renal function in patients undergoing endovascular repair (EVR) of abdominal aortic aneurysm (AAA).

METHODS

Consecutive EVR patients for AAA from December 1995-2001 were included and grouped to either infrarenal (Group 1) or uncovered suprarenal (Group 2) fixation. Peri-operative renal function and at 6, 12 and 24 months was determined by serum creatinine (sCr mmol l(-1)) and Cockroft-Gault creatinine clearance (CrC ml min(-1)). Changes in renal function were compared using non-parametric analysis.

RESULTS

Of the 179 EVR procedures during this six-year period, paired renal data was available for 135 patients at a minimal follow-up of 6 months (Gp1, n = 63; Gp2, n = 72). Median pre-EVR sCr and CrC were 113, 57 in Group 1 and 108, 58 in Group 2, p = NS. There was no significant deterioration in renal function within or between either group at 2 years post-EVR: median sCr, CrC values were 118, 56 (Group 1) and 111, 56 (Group 2), all p = NS.

CONCLUSION

This study suggests mid-term renal function remains unaffected following EVR of AAA, irrespective of proximal fixation type. Designs to improve stent durability and EVR applicability do not appear to compromise renal function.

Current Status of Endovascular Repair of Infrarenal Abdominal Aortic Aneurysms in the Context of 50 Years of Conventional Repair

The operative risk for conventional open repair of nonruptured infrarenal abdominal aortic aneurysms (AAAs) has steadily declined during the past several decades to the point that open procedures now can be done with a mortality rate of approximately 2% at tertiary referral centers. Nevertheless, population-based studies suggest that the mortality rate for open AAA repair remains nearly 7% in many communities, a finding that undoubtedly is influenced by a substantial risk for unfavorable outcomes in patients who represent less than ideal candidates for major abdominal operations on the basis of advanced age and the medical comorbidities that so often accompany it. Endovascular aneurysm repair (EVAR) is a landmark contribution to the management of such patients and has been associated with significant overall reductions in the operative mortality rate in statewide and national audits. This early advantage of EVAR comes at the price of a unique set of complications, secondary interventions, and related expenses, however, and randomized clinical trials of EVAR versus open repair have not yet demonstrated differences in survival or quality of life within 4 years of follow-up. Data from the Nationwide Inpatient Sample and other sources indicate that the mortality rate for open AAA repair appears to be less than 2% in patients who are 65 years of age or younger. This low operative risk may not justify exposure to whatever incidence of late complications the current generation of endografts may prove to have during the relatively long survival times that can be anticipated for these patients.

Technology Penetration of Endovascular Aortic Aneurysm Repair in Southern California

Our objective was to investigate the penetration of endovascular abdominal aortic aneurysm repair (EVAR) in the large, diverse health-care market of southern California over 3 years and to study variability in the pattern of distribution of EVAR in southern California counties by analyzing available demographic, geographic, and socioeconomic data from California state health-care databases. Information abstracted from the inpatient hospital discharge data for patients undergoing AAA repair for the years 2001, 2002, and 2003, derived from the Office of Statewide Health Planning and Development, included age, gender, race, hospitals performing EVAR, and payors for the service. Per-capita income (PCI) for the year 1999 and the population size of each county for the respective years were obtained from the U.S. Census Bureau. Data pertaining to members of the Southern California Vascular Surgical Society (SCVSS) serving the southern California region were obtained from the SCVSS membership directory. Data were categorized based on 10 counties in southern California. All the above variables were analyzed using the chi-squared test, with p < 0.05 considered significant. The proportions of EVAR for the years 2001, 2002, and 2003 were 15.4% (n = 409), 20.2% (n = 492), and 25.9% (n = 566), respectively. This is a 67.8% (p < 0.0001) increase in EVAR application in southern California since 2001. However, the proportion of EVAR varied among counties (p < 0.0001), with 457 EVARs performed in Los Angeles County and eight in Imperial County during the study period. EVAR proportion was higher in patients aged > or =65 years (p < 0.0001) and male patients (p < 0.0001). The proportion of EVAR was significantly higher in counties with more than 20 vascular surgeons available (p < 0.0001) and PCI >21,000 US$ (p < 0.0001) and in Medicare, health maintenance organization, preferred provider organization, and private insurance holders (p < 0.0001). There was a trend toward increased EVARs in counties with more than eight hospitals that performed EVAR (p = 0.0545). However, no significant difference in EVAR proportion was observed among subgroups based on race (p = 0.535) and population size (p = 0.84). Although the number and proportion of EVAR increased significantly in southern California over 3 years, the penetration of the procedure varied among counties. County affluence, payor mix, and the number of vascular surgeons/county influenced the variability. These observations suggest that economic barriers may limit access to new biomedical technology. This has implications for health-care public policy directed toward providing equal access to medical care without regard to economic status.

Incidence and Effect of Bare Suprarenal Stent Struts Crossing Renal Ostia Following EVAR

OBJECTIVES

The incidence and effect of bare stent struts crossing the renal ostia following endovascular aortic aneurysm repair with the Talent stent-graft is not known. The study aims to establish the incidence in which bare stent struts cross the renal ostia and to assess any associated effects on renal function.

METHODS

Fifty-five patients (51 men, mean age 73 years, range 57-90) who had endovascular repair of their abdominal aortic aneurysms with a Talent suprarenal stent-graft were included in the study. Patients were scanned at a variety of follow-up periods (median 24 months, range 3-102). The relationship between the bare stent struts and the renal ostia, together with renal function were retrospectively recorded. The presence and location of the bare stent struts was assessed using CT virtual intravascular endoscopy (CT VIE). Struts were defined as being absent, peripherally located or in the central channel of the renal ostia. Renal function was assessed from glomerular filtration rates (GFR) derived from serum creatinine levels and the Cockcroft and Gault formula.

RESULTS

A total of 109 renal ostia were evaluated by CT VIE with one patient having a previous nephrectomy. Bare stent struts crossed 1 renal ostium in 22 (40%) patients and bilateral ostia in 5 (9%) patients. Of the 109 ostia assessed, 15 (14%) ostia were crossed centrally and 17 (16%) had struts crossing the ostium peripherally. There were no statistically significant differences in the change between pre-operative GFR and latest GFR in the group without any strut involvement (6 mLs/min +/- 7 mLs/min) and the group with struts crossing one or both renal ostia (2 mLs/min +/- 9 mLs/min; p > .05).

CONCLUSION

Peripheral or central coverage of renal ostia by bare stent struts occurs in a third of all renal arteries following EVAR. Crossing of renal ostia by bare stent struts does not affect follow-up GFR.

A Randomised Trial of Endovascular and Open Surgery for Ruptured Abdominal Aortic Aneurysm – Results of a Pilot Study and Lessons Learned for Future Studies

INTRODUCTION

EVAR has the potential to improve outcome after ruptured abdominal aortic aneurysm (AAA). Published series have been based upon selected populations.

METHODS

An interim analysis of a single centre prospective randomised controlled trial comparing endovascular aneurysm repair (EVAR) with open aneurysm repair (OAR) in patients with ruptured AAA was performed. Patients who had a ruptured AAA and who were considered fit for open repair were randomised to EVAR or OAR after consent had been obtained. Those in the EVAR group had pre-operative spiral computed tomographic angiography (CTA). The primary endpoint was operative (30-day) mortality and secondary endpoints were moderate or severe operative complications, hospital stay and time between diagnosis and operation. A power study calculation required 100 patients to be recruited.

RESULTS

Between September 2002 and December 2004, 103 patients were admitted with suspected ruptured AAA. Only 32 patients were recruited to the study. Of these, four patients died before receiving surgical treatment. On an intention to treat basis the 30-day mortality rate was 53% in the EVAR group and 53% in the OAR group. Moderate or severe operative complications occurred in 77% in the EVAR group and in 80% in the OAR group. Median total hospital stay in the EVAR group was 10 days (inter-quartile range 6-28) and 12 days (4-52) in the OAR group. Median time between diagnosis and operation was 75 minutes (64-126) in the EVAR group and 100 minutes (48-138) in the OAR group.

CONCLUSIONS

Despite the relative high operative mortality in the EVAR group, these preliminary results show that it is possible to recruit patients to a randomised trial of OAR and EVAR in patients with ruptured AAA. CT scanning does not delay treatment.

Can Induced Anxiety from a Negative Earlier Experience Influence Vascular Surgeons’ Statistical Decision-Making? A Randomized Field Experiment with an Abdominal Aortic Aneurysm Analog

BACKGROUND

Increasing detection, new screening recommendations, and popular press attention contribute to the rising prevalence of asymptomatic abdominal aortic aneurysms (AAA). Evidence-based guidelines recommend the optimal time to operate is when the aneurysm is 5.5 cm in diameter. Smaller AAAs are periodically monitored with imaging. Recent events and emotional reactions to risk and uncertainty, including anxiety, can cause decision-making to diverge from cognitively based assessments. It is not known whether this applies to vascular surgeons making statistically-optimal, risky decisions. We tested whether an unexpected, recent negative event might influence vascular surgeons' decisions about a computer-simulation AAA-analog that includes statistical information.

STUDY DESIGN

We performed a randomized, computer-based field experiment with evidenced-based statistical information readily available on bursting probabilities. Participants included vascular surgeons with AAA operative experience attending two vascular surgery conferences held in 2005 (n=81). The intervention was a randomly assigned, anxiety-inducing, bursting balloon versus a nonbursting balloon before a statistical decision-making computer simulation. The main outcomes measure was real-time prospective choice to opt out of expanding AAA simulation. A Cox proportional hazard model was used to assess the likelihood of opting out, while controlling for important covariates.

RESULTS

The experimental group was more likely to opt out (hazard ratio: 3.32; 95% CI: 1.25 to 8.81), even after controlling for initial anxiety levels, risk attitudes, uncertainty attitudes, use of statistical information, surgical experience, and demographics.

CONCLUSIONS

Experiencing a negative, potentially anxiety-provoking, preceding event can influence decision-making, even among experienced vascular surgeons who have ready access to statistical risk information.

Endovascular aneurysm repair at 5 years: does aneurysm diameter predict outcome?

OBJECTIVE

The appropriate size threshold for endovascular repair of small abdominal aortic aneurysms (AAA) is unclear. We studied the outcome of endovascular aneurysm repair (EVAR) as a function of preoperative aneurysm diameter to determine the relationship between aneurysm size and long-term outcome of endovascular repair.

METHODS

We reviewed the results of 923 patients treated in a prospective, multicenter clinical trial of EVAR. Small aneurysms were defined according to two size thresholds of 5.5 cm and 5.0 cm. Two-way analysis was used to compare patients with small aneurysms (<5.5 cm, n = 441) to patients with large aneurysms (> or =5.5 cm, n = 482). An ordered three-way analysis was used to compare patients with small AAA (<5.0 cm, n = 145), medium AAA (5.0 to 5.9 cm, n = 461), and large AAA (> or =6.0 cm, n = 317). The primary outcome measures of rupture, AAA-related death, surgical conversion, secondary intervention, and survival were compared using Kaplan-Meier estimates at 5 years.

RESULTS

Median aneurysm size was 5.5 cm. The two-way comparison showed that 5 years after EVAR, patients with small aneurysms (<5.5 cm) had a lower AAA-related death rate (1% vs 6%, P = .006), a higher survival rate (69% vs 57%, P = .0002), and a lower secondary intervention rate (25% vs 32%, P = .03) than patients with large aneurysms (> or =5.5 cm). Three-way analysis revealed that patients with small AAAs (<5.0 cm) were younger (P < .0001) and were more likely to have a family history of aneurysm (P < .05), prior coronary intervention (P = .003), and peripheral occlusive disease (P = .008) than patients with larger AAAs. Patients with smaller AAAs also had more favorable aortic neck anatomy (P < .004). Patients with large AAAs were older (P < .0001), had higher operative risk (P = .01), and were more likely to have chronic obstructive pulmonary disease (P = .005), obesity (P = .03), and congestive heart failure (P = .004). At 5 years, patients with small AAAs had better outcomes, with 100% freedom from rupture vs 97% for medium AAAs and 93% for large AAAs (P = .02), 99% freedom from AAA-related death vs 97% for medium AAAs and 92% for large AAAs (P = .02) and 98% freedom from conversion vs 92% for medium AAAs and 89% for large AAAs (P = .01). Survival was significantly improved in small (69%) and medium AAAs (68%) compared to large AAAs (51%, P < .0001). Multivariate Cox proportional hazards modeling revealed that aneurysm size was a significant independent predictor of rupture (P = .04; hazard ratio [HR], 2.195), AAA-related death (P = .03; HR, 2.007), surgical conversion (P = .007; HR, 1.827), and survival (P = .001; HR, 1.351). There were no significant differences in secondary intervention, endoleak, or migration rates between small, medium, and large AAAs.

CONCLUSIONS

Preoperative aneurysm size is an important determinant of long-term outcome following endovascular repair. Patients with small AAAs (<5.0 cm) are more favorable candidates for EVAR and have the best long-term outcomes, with 99% freedom from AAA death at 5 years. Patients with large AAAs (> or =6.0 cm) have shorter life expectancy and have a higher risk of rupture, surgical conversion, and aneurysm-related death following EVAR compared to patients with smaller aneurysms. Nonetheless, 92% of patients with large AAAs are protected from AAA-related death at 5 years. Patients with AAAs of intermediate size (5 to 6 cm) represent most of the patients treated with EVAR and have a 97% freedom from AAA-related death at 5 years.

Aortic Aneurysm, Thoracoabdominal Aneurysm, Juxtarenal Aneurysm, Fenestrated Endografts, Branched Endografts, and Endovascular Aneurysm Repair

The development of endovascular devices to treat aneurysms that abut or involve the visceral vessels has occurred in an effort to reduce the significant procedural morbidity and mortality associated with conventional repair. To accomplish this, three systems have been trialed. The first technique was developed to treat juxtarenal aneurysms and involves the placement of customized fenestrations strategically placed within the fabric of the graft. These are aligned with the ostia of the visceral vessels incorporated by the repair and supplemented by the placement of a balloon expandable stent. In a similar fashion, aneurysms that involve the visceral vessels can be treated with a fenestrated graft where the fenestration is reinforced with a nitinol ring. This is then mated with a balloon-expandable stentgraft, allowing the devices to seal at the level of the nitinol ring. An alternative means of incorporating the visceral vessels is to use directional branches where one or more additional limbs (typically 8 mm) are anastomosed to the aortic graft, through which access into the visceral vessel is attained. Mating stentgrafts for the later design can be of a self-expanding or balloon expandable nature. The experience with fenestrated devices is mature and associated with a low perioperative mortality (<2%) without many long-term complications. The treatment of thoracoabdominal aneurysms with branches has provided us with optimism regarding the technique, but results are only short term in nature. Further device development is ongoing and dissemination of this technology is now occurring in Europe, Australia and Canada.

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.

Endovascular stent graft repair for infected thoracic aortic pseudoaneurysms—a durable option?

OBJECTIVE

Open surgical repair for infected thoracic aortic pseudoaneurysms carries significant mortality and morbidity. Endovascular stent graft repair has been our preferred approach, although its role remains controversial because persistent infection is always a concern. We aimed to assess the efficacy and durability of endovascular stent graft repair in these patients.

METHODS

Between August 2000 and November 2005, seven consecutive patients with eight infected pseudoaneurysms of the thoracic aorta were treated with endovascular stent graft repair. Patients were diagnosed based on a typical appearance of an infected pseudoaneurysm on imaging together with a positive bacteriology culture or clinical evidence of sepsis. The follow-up protocol included regular clinical examination, hematologic tests, and computed tomography scans.

RESULTS

There were six men and one woman with a median age of 68 years at operation. Three patients presented with an aortoenteric fistula. The operations were performed in the operating room with the image guidance of a mobile C-arm. Endovascular stent grafts were deployed successfully in all patients, with complete exclusion of the pseudoaneurysms. Intravenous antibiotics were continued for 1 to 6 weeks and followed by lifelong maintenance oral antibiotics. The median hospital stay was 27 days, with no hospital deaths. No paraplegia or other major complications occurred. Two patients with aortoesophageal fistula where the fistula tracts were persistent died during follow-up. The other five patients remained well, with no evidence of graft infection at a median follow-up of 34 months. A significant reduction in the diameter of the pseudoaneurysm (>5 mm) was noted on computed tomography scans after 12 months.

CONCLUSION

Endovascular stent graft repair is effective and may be a durable option for infected pseudoaneurysms of the thoracic aorta.

Propensity score analysis in observational studies: outcomes after abdominal aortic aneurysm repair

OBJECTIVE

Large databases composed of well-designed prospectively collected cohort data provide an opportunity to examine and compare healthcare treatments in actual clinical practice settings. Because the analysis of these data often leads to a retrospective cohort design, it is essential to adequately adjust for lack of balance in patient characteristics when making treatment comparisons. We used matched propensity scoring in a cohort of patients undergoing elective aneurysm repair as an illustrative example of this important statistical method that adjusts for baseline characteristics and selection bias by matching covariables.

METHODS

By using prospectively collected clinical data from the National Surgical Quality Improvement Program of the Department of Veterans Affairs, we studied 30-day mortality, 1-year survival, and postoperative complications in 1904 patients who underwent elective AAA repair (endovascular aneurysm repair [EVAR], n=717 (37.7%); open aneurysm repair, n=1187 [62.3%]) at 123 Veterans Health Administration's hospitals between May 1, 2001, and September 30, 2003. In bivariate analysis, patient characteristics and operative and hospital variables were associated with both type of surgery and outcomes of surgery. Therefore, the predicted probability of receiving EVAR was tabulated for all patients by using multiple logistic regression to control for 32 independent demographic and clinical characteristics and then stratified into 5 groups. Patients were matched within strata based on similar levels of the independent measures (a propensity score technique), creating a pseudo-randomized control design. The proportion of patients with the morbidity and mortality outcomes was then compared between the EVAR and open procedures within strata to control for selection.

RESULTS

Patients undergoing EVAR had significantly lower unadjusted 30-day (3.1% versus 5.6%, P=.01) and 1-year mortality (8.7% versus 12.1%, P=.018) than patients undergoing open repair. By using propensity scoring, the proportions of EVAR patients experiencing 30-day mortality were equal or less than patients undergoing open procedures for all levels of probability and decreased as the probability of EVAR increased. Furthermore, propensity scoring also showed that patients having EVAR had lower 1-year mortality and experienced fewer perioperative complications.

CONCLUSIONS

We used a propensity score approach to examine outcomes after elective AAA repair to statistically control for many factors affecting both treatment selection and outcome. Patients who underwent elective EVAR had substantially lower perioperative mortality and morbidity rates compared with patients having open repair, which was not explained solely by patient selection in an observational dataset.

Complications of Endovascular Repair of Abdominal Aortic Aneurysms: A Review

The endovascular procedure for repair of abdominal aortic aneurysms has had an enormous impact on the treatment of this challenging disease. Complications, however, do occur and it is important to have a thorough understanding of the array of complications and appropriate management strategies. In this review of endovascular complications, we describe early and late complications paying particular attention to preventive, treatment and surveillance strategies.

The influence of aneurysm size on perioperative cardiac outcome in elective open infrarenal aortic aneurysm repair

BACKGROUND

Abdominal aortic aneurysm (AAA) size and growth has been found to be associated with local generation of inflammation markers such as interleukin-6. Inflammation also seems to be important in perioperative adverse cardiac events. We hypothesized that patients with a large AAA are at increased risk for cardiac events.

METHODS

Consecutive patients who underwent a computed tomography angiography scan before open elective infrarenal AAA repair between March 2000 and December 2005 at three hospitals were analyzed. All patients were screened for the clinical risk factors of age, gender, angina pectoris, myocardial infarction, heart failure, diabetes, stroke, renal failure, and chronic obstructive pulmonary disease, as well as for cardioprotective medication. Postoperative data on troponin release, creatine kinase/creatine kinase isoenzyme MB, and electrocardiogram were routinely collected on days 1, 3, 7, and 30. The main outcome measure was the combined end point of 30-day cardiovascular death and nonfatal myocardial infarction. Multivariate Cox regression analysis was used to evaluate the influence of AAA size on postoperative cardiac outcome.

RESULTS

The study included 500 patients. Their mean age was 69.8 +/- 9.5 years, and 431 (86%) were men. Thirty-one patients (6.2%) had perioperative cardiovascular complications, consisting of 15 (3.0%) cardiovascular deaths and 16 (3.2%) nonfatal myocardial infarctions. After correction for other risk factors, including age, Revised Cardiac Risk Index, medication use, duration of surgery, and intraoperative blood loss, AAA size was independently associated with perioperative nonfatal myocardial infarction and cardiovascular death (3.2% increase in risk for each millimeter added, 95% confidence interval 1.1% to 6.2%, P = .007).

CONCLUSION

A larger AAA size is independently associated with an increased incidence of perioperative cardiovascular complications after elective infrarenal AAA repair.

Endoleaks after endovascular repair of thoracic aortic aneurysms

OBJECTIVE

Endoleaks are one of the unique complications seen after endovascular repair of thoracic aortic aneurysms (TEVAR). This investigation was performed to evaluate the incidence and determinants of endoleaks, as well as the outcomes of secondary interventions in patients with endoleaks, after TEVAR.

METHODS

Over a 6-year period, 105 patients underwent TEVAR in the context of pivotal Food and Drug Administration trials with the Medtronic Talent (n = 64) and Gore TAG (n = 41) devices. The medical and radiology records of these patients were reviewed for this retrospective study. Of these, 69 patients (30 women and 39 men) had follow-up longer than 1 month and were used for this analysis. The patients were evaluated for the presence of an endoleak, endoleak type, aneurysm expansion, and endoleak intervention.

RESULTS

The mean follow-up in this patient cohort was 17.3 +/- 14.7 months (range, 3-71 months). Endoleaks were detected in 29% (20/69) of patients, of which 40% (8/20) were type I, 35% (7/20) were type II, 20% (4/20) were type III, and 5% (1/20) had more than one type of endoleak. Patients without endoleaks experienced greater aneurysm sac regression than those with endoleaks (-2.89 +/- 9.1 mm vs -0.13 +/- 7.2 mm), although this difference was not statistically significant (P = .232). All but 2 endoleaks (90%; 18/20) were detected on the initial postoperative computed tomographic scan at 30 days. Two endoleaks (10%; 2/20) developed late. The endoleak group had more extensive aneurysms with significantly larger aneurysms at the time of intervention (69.4 +/- 10.5 mm vs 60.6 +/- 11.0 mm; P = .003). Factors predictive of endoleak included male sex (P = .016), larger aneurysm size (P = .003), the length of aorta treated by stent grafts (P = .0004), and an increasing number of stents used (P < .0001). No open conversions were performed for treatment of endoleaks. Four (50%) of the eight type I endoleaks were successfully repaired by using endovascular techniques. None of the type II endoleaks was treated by secondary intervention. During follow-up, the maximum aneurysm diameter in the type II endoleak patients increased a mean of 2.94 +/- 7.2 mm (range, -4.4 to 17 mm). Spontaneous thrombosis has occurred in 29% (2/7) of the type II endoleaks. Patients with type III endoleaks experienced a decrease in mean maximal aneurysm diameter of 0.78 +/- 3.1 mm during follow-up.

CONCLUSIONS

Endoleaks are not uncommon after TEVAR. Many type I endoleaks may be treated successfully by endovascular means. Short-term follow-up suggests that observational management of type II endoleaks is associated with continued sac expansion, and these patients should be monitored closely.

A comparison of renal function between open and endovascular aneurysm repair in patients with baseline chronic renal insufficiency

OBJECTIVE

Endovascular aneurysm repair (EVAR) is rapidly becoming the predominant technique for repair of abdominal aortic aneurysms. Results from current studies, however, are conflicting on the effect of EVAR on renal function compared with standard open repair. Furthermore, data for open repair in patients with baseline renal insufficiency suggests worse outcomes, including renal function. This analysis compared the effects of open repair vs EVAR on renal function in patients with baseline renal insufficiency.

METHODS

We reviewed our records for patients with preoperative chronic renal insufficiency (serum creatinine, 1.5 mg/dL) who underwent open repair or EVAR between 1999 and 2004. The same group of vascular surgeons at a single institution performed aneurysm repair on 98 patients: 46 open (37 men, 9 women) and 52 EVAR (50 men, 2 women). Preoperative, postoperative, and follow-up serum creatinine and creatinine clearance were compared, as was the development of postoperative renal impairment (increase in serum creatinine >30%).

RESULTS

Serum creatinine and creatinine clearance were not statistically different between the open and EVAR groups during any time period studied. Likewise when comparing the magnitude of change in serum creatinine in patients between the postoperative and follow-up times with preoperative values, no significant differences existed between the open and EVAR groups. When the change in serum creatinine over time within each group was compared, however, the open group had a significant increase in serum creatinine postoperatively (2.43 +/- 1.20 vs 2.04 +/- 0.64, P = .012), which returned to baseline during follow-up (1.96 +/- 0.94, P = .504). Although serum creatinine in the EVAR group increased compared with preoperative values of 2.04 +/- 0.55 (postoperative, 2.27 +/- 1.04; follow-up, 2.40 +/- 1.37), this failed to reach statistical significance for the postoperative (P = .092) or follow-up (P = .081) periods. A similar pattern was noted in creatinine clearance. Postoperative renal impairment was noted in 13 open (28%) and 15 EVAR patients (29%) and was not statistically different between groups. Overall, two patients (4.3%) from the open group and four (7.7%) from the EVAR group required hemodialysis; one in the EVAR group required permanent hemodialysis. This difference was not statistically significant (P = .681).

CONCLUSIONS

Open and endovascular repair of abdominal aortic aneurysms in patients with pre-existent renal insufficiency can be performed safely with preservation of renal function. In contrast to previous reports, no significant differences existed between open repair and EVAR in postoperative alterations in renal function. Although a significant increase in serum creatinine develops in patients with renal insufficiency postoperatively with open repair, this appears to be transient, and preoperative renal dysfunction alone should not exclude either approach. After EVAR, patients with pre-existing renal insufficiency continue to be at risk for progressive renal dysfunction, and protective measures should be taken to preserve renal function in this patient population.

Mid-term results of endovascular aneurysm repair with branched and fenestrated endografts

PURPOSE

The technique of fenestrated and branched endovascular aneurysm repair (EVAR) has been used for the treatment a variety of aortic aneurysms. Although technically successful, longer-term results have been lacking. This article reports on the mid-term results of aneurysm repair with fenestrated and branched endografts from a European center with a large endovascular experience.

METHODS

Between 2001 and 2005, 38 patients were prospectively enrolled in a single institution, investigational device protocol database. Indications for fenestrated or branched EVAR included unfavorable anatomy for traditional EVAR and an abdominal aortic aneurysm >5.5 cm in maximum diameter. Customized stent-grafts were either fenestrated or branched and based on the Zenith system. Data were analyzed on an intention-to-treat basis. Differences between groups were determined using analysis of variance with P < .05 considered significant.

RESULTS

The mean (SD) follow-up was 25.8 +/- 12.7 months (median, 25.0 months; range, 9 to 46 months), and no patients were lost to follow-up. All cause mortality was 13% (5/38), with all deaths occurring within the first postoperative year; 30-day mortality was 2.6%. No patient died during the operation. Completion angiography demonstrated successful sealing in 37 of 38 patients and an overall operative visceral vessel perfusion rate of 94% (82/87). Cumulative visceral branch patency was 92% at 46 months. Stent occlusions, when they did occur, all happened within the first postoperative year. All postoperative occlusions occurred in unstented fenestrations or scallops. No occlusions occurred in stented vessels. The difference in serum creatinine preoperatively and postoperatively at 6 months, 1, 2, and 3 years was not significant (P = NS). No patient required dialysis. The aneurysm sac size decreased significantly during the first year and then remained stable (P < .05). Limb perfusion as assessed by the ankle/brachial index was not affected by the presence of a fenestrated or branched endograft.

CONCLUSIONS

The intermediate-term results of fenestrated and branched endografts support their continued use in patients with anatomic contraindications for standard EVAR. Close surveillance is mandatory for early identification of visceral or branched vessel stenosis and preocclusion. All cases of failure appear to occur during the first year and then level off in subsequent longer-term follow-up. This includes death, secondary interventions, branch vessel patency, and complications. As the procedure matures, long-term results and randomized clinical trials will ultimately be required to determine the safety, efficacy, and stability of this system.

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.

Combined Staged Procedures for the Treatment of Thoracoabdominal Aneurysms

PURPOSE

To examine the efficacy of a staged approach for the treatment of thoracoabdominal aneurysms, with open visceral revascularization followed by aortic endografting, in selected patients not considered candidates for conventional surgical repair.

METHODS

A retrospective review was conducted of 13 consecutive patients (8 women; mean age 64 years, range 33-77) who underwent visceral bypass followed by endovascular thoracoabdominal stent-graft implantation since 1999. Three patients presented with symptomatic aneurysms and 2 with rupture. Two patients had connective tissue disorders. All patients were deemed unfit for conventional thoracoabdominal repair due to comorbid conditions. The procedures were tailored to the pathology and specific patient anatomical situation: 5 aortic dissections with aneurysmal degeneration and 8 aneurysms (5 Crawford type II, 2 type III, and 1 type IV).

RESULTS

The patients underwent retrograde visceral bypass (11 iliovisceral and 2 infrarenal aortic to visceral artery) followed by endovascular aortic relining with Zenith TX2 devices (n=7), homemade endografts (n=5), or a Talent thoracic endograft (n=1). Six patients required either a proximal or distal direct aortic repair (2 infrarenal reconstructions, 3 arch elephant trunk grafts, and 1 ascending aortic repair), while 3 patients also underwent left carotid-subclavian bypass grafting. Two patients developed paraplegia (1 following a ruptured aneurysm), and 2 patients had transient paraparetic events. Two patients had acute renal failure requiring short-term dialysis. Three patients died within 30 days; 2 late aneurysm-related deaths were noted. Three patients developed endoleaks during follow-up. Mean lengths of stay were 13 days (7-30) for the visceral bypass and 12 (3-25) for the endovascular stent-graft. In addition, remaining procedures in 8 patients required a mean of 7 days (0-14) in hospital.

CONCLUSION

Staged endovascular and open procedures are feasible for thoracoabdominal aneurysms in patients at prohibitive risk for open thoracoabdominal reconstruction. However, this approach still carries a significant risk of perioperative mortality and morbidity. The potential for less invasive alternatives should be investigated.