Outcome after endovascular abdominal aortic aneurysm repair: a meta-analysis

Prevention of Spinal Cord Injury during Thoracoabdominal Aortic Aneurysms Repair: What the Anaesthesiologist Should Know

Thoraco-abdominal aortic repair is a high-risk surgery for both mortality and morbidity. A major complication is paraplegia-paralysis due to spinal cord injury. Modern thoracic and abdominal aortic aneurysm repair techniques involve multiple strategies to reduce the risk of spinal cord ischemia during and after surgery. These include both surgical and anaesthesiologic approaches to optimize spinal cord perfusion by staging the procedure, guaranteeing perfusion of the distal aorta through various techniques (left atrium–left femoral artery by-pass) by pharmacological and monitoring interventions or by maximizing oxygen delivery and inducing spinal cord hypothermia. Lumbar CSF drainage alone or in combination with other techniques remains one of the most used and effective strategies. This narrative review overviews the current techniques to prevent or avoid spinal cord injury during thoracoabdominal aortic aneurysms repair.

Computational analysis of endovascular aortic repair proximal seal zone preservation with endoanchors: A case study in cylindrical neck anatomy

Background

Endovascular aortic repair is the common approach for abdominal aortic aneurysms, but endoleaks remain a significant problem with long-term success. Endoanchors have been found to reduce the incidence of type 1A endoleaks and can treat intraoperative type 1a endoleaks. However, little is known about the optimal number and position of endoanchors to achieve the best outcome.

Methods

Using image segmentation and a computational model derived from a reconstructed native patient abdominal aortic aneurysm geometry, the stability of the proximal seal zone was examined through finite element analysis in Abaqus (Dassault Systèmes, Providence, RI). The biomechanical parameter of contact area was compared for varying numbers (0, 2, 4, 8) and positions (proximal, medial, distal) of endoanchors under different adhesion strengths and physiologic pressure conditions.

Results

In every simulation, an increase in adhesion strength is associated with maintenance of proximal seal. For biologically plausible adhesion strengths, under conditions of normal blood pressure (120 mm Hg), the addition of any number of endoanchors increases the stability of the endograft-wall interface at the proximal seal zone by approximately 10% compared with no endoanchors. At hypertensive pressures (200 mm Hg), endoanchors increase the stability of the interface by 20% to 60% compared with no endoanchors. The positioning of endoanchors within the proximal seal zone has a greater effect at hypertensive pressures, with proximal positioning increasing stability by 15% compared with medial and distal positioning and 30% compared with no endoanchors.

Conclusions

Endoanchors improve fixation within the proximal seal zone particularly under conditions of high peak systolic pressure. Seal zone stabilization provides a mechanism through which endoanchor addition may translate into lower rates of type 1a endoleaks for patients.

Endovascular aortic repairs are commonly used to treat abdominal aortic aneurysms. Type 1a endoleaks threaten the long-term durability of repairs. Endoanchors have been found to reduce the incidence of this complication. Herein, we examine parameters surrounding optimal endoanchor number and positioning to reduce endovascular aortic repair failure. The computational modeling allowed for testing of endoanchors in varied adhesion strength between the endograft and the aorta, as well as hemodynamic conditions to mimic normotension vs hypertension. The results of the finite element analysis suggest that the addition of any number of endoanchors in the proximal seal zone is beneficial, especially with hypertensive loading.

ePTFE-based biomedical devices: An overview of surgical efficiency

Polytetrafluoroethylene (PTFE) is a ubiquitous material used for implants and medical devices in general because of its high biocompatibility and inertness: blood vessel, heart, table jawbone, nose, eyes, or abdominal wall can benefit from its properties in case of disease or injury. Its expanded version, ePTFE is an improved version of PTFE with better mechanical properties, which extends its medical applications. A material as frequently used as ePTFE with these exceptional properties deserves a review of its main uses, developments, and possibility of improvements. In this systematic review, we examined clinical trials related to ePTFE-based medical devices from the literature. Then, we excluded all trials using ePTFE as a control to test other devices. ePTFE-coated stents, hemodialysis and bypass grafts, guided bone and tissue regeneration membranes, hernia and heart repair and other devices are reviewed. The rates of success using these devices and their efficiency compared to other materials used for the same purposes are reported. ePTFE appears to be more or just as efficient compared to them. Some success rates remain low, suggesting the need of improvement ePTFE for medical applications.

Monitored Anesthesia Care Is Associated With a Decrease in Morbidity After Endovascular Angioplasty in Aortoiliac Disease

OBJECTIVES

Few studies have evaluated the association between anesthesia type and outcomes after endovascular angioplasty/stents for aortoiliac occlusive disease. The aim of the present study was to evaluate the association between primary anesthesia type and postprocedural complications for endovascular angioplasty of aortoiliac occlusion.

DESIGN

Retrospective cohort study.

SETTING

Multi-institutional.

PARTICIPANTS

The study comprised 3,110 patients undergoing endovascular angioplasty of aortoiliac occlusive disease, with 1,974 and 1,136 patients who underwent monitored anesthesia care (MAC) and general anesthesia (GA), respectively. The American College of Surgeons National Surgical Quality Improvement Program database for the years 2012 to 2016 was used for the present study.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The final analysis included 3,110 patients, 63% of whom received MAC and 37% of whom received GA. The mean age was 64 years among the GA group, of whom 57.2% were male. The mean age among that MAC group was 65 years, 55.8% of whom were male. After adjusting for demographic factors and preoperative comorbidities, there was a statistically significant lower odds of postoperative complications (ie, pulmonary complications, infection, intraoperative/postoperative transfusion, reoperation, and amputation) and shorter length of stay in the MAC group compared with the GA group (p < 0.05).

CONCLUSIONS

Although larger observational studies and randomized controlled trials are needed to further evaluate the potential effect of MAC versus GA, MAC anesthesia should be considered for patients undergoing endovascular angioplasty for aortoiliac occlusion.

Anesthetic Management for Endovascular Repair of the Thoracic Aorta

Thoracic endovascular aneurysm repair (TEVAR) is fast becoming the primary treatment of thoracic aortic aneurysms, thoracic aortic dissections, acute aortic injuries, and other conditions affecting the thoracic aorta. Patients scheduled for TEVAR tend to have a host of comorbid conditions, including coronary artery disease, diabetes, and chronic obstructive pulmonary disease. Intraoperative management should optimize end-organ perfusion, facilitate neuromonitoring, and adjust hemodynamic management. Complications include spinal cord injury, peripheral vascular injury, contrast-induced nephropathy, postimplantation syndrome, and endoleaks. Patients who undergo TEVAR require care in a postoperative environment where these complications can be rapidly detected and aggressively treated.

Abdominal Aortic Aneurysm Repair in Octogenarians versus Younger Patients in a Tertiary Referral Center

Operative survival is as high as 96% for elective abdominal aortic aneursym (AAA) repair but as low as 10% for emergency repair. Our primary aim was to compare elective AAA repair in octogenarians with nonoperative management. Our secondary aim was to compare octogenarians with their younger counterparts.

From 1998 to 2003, 180 patients with AAA were treated operatively or nonoperatively. Factors determining treatment included American Society of Anesthesiologists grade ≥ 4, inoperable malignancy, New York Heart Association class III, forced expiratory volume in 1 second < 35%, creatinine > 6.0 mg/dL, and patient and family choice. A parallel-group observational study was performed to assess age and treatment effects on outcome.

Seventy (39%) patients were repaired electively, 68 (38%) were managed nonoperatively, and 42 (23%) underwent emergency repair. Fifty-nine (33%) were octogenarians.

The octogenarian 5-year survival rate was 20% following emergency repair, 42% if treated nonoperatively, and 83% following elective repair. Younger cohort rates were 55% (emergency), 44% (nonoperative), and 76% (elective).

The octogenarian mean expansion rate was 0.26 cm/yr in those treated nonoperatively and 1.04 cm/yr in confirmed rupture. Rupture rate was related to expansion rate (95% confidence interval [CI] 0.06–0.59, r = .35, p = .01). The rates in the younger subgroup were 0.32 cm/yr and 1.14 cm/yr (95% CI −0.021–0.672}, r = .37, p = .03).

The octogenarian survival rate was highest following elective repair. Rupture was closely correlated with aneurysm expansion. Screening should reduce the incidence of octogenarian rupture of AAA and identify those patients most suitable for nonoperative management.

Early Elective Conversion for Failing Evar

Background:

The aim of the study was to assess the long term results of endovascular aneurysm repair (EVAR) of abdominal aortic aneurysms at the Helsinki University Central Hospital 1996–2004 with a special emphasis on elective conversion procedures and their outcome.

Methods:

Treatment results and follow-up data of all 110 elective EVAR procedures performed in our institution were gathered prospectively and evaluated.

Results:

Conversion to open surgery was performed in 23 (21%) of 110 EVAR patients. 30-day mortality after elective stent-graft deployment was 0% as it was also on elective conversions (n = 20). Secondary elective conversions were performed due to infection in two and after failing stent-graft treatment in 12 patients. Six of the conversions were performed primarily. Three urgent conversions (3% overall) were performed: two of these patients died, corresponding to an overall mortality of 9% (2/23) in all conversions. Five-year aneurysm-related mortality after EVAR among patients with elective conversion was 0% and 19% in patients with secondary procedures other than elective conversions.

Conclusions:

As conversions seem to be hazardous only when performed in urgent situations, elective conversion could be an alternative treatment method in complex failing first-generation stent-grafts as it may reduce mortality associated with urgent conversions or repeated attempts to maintain graft integrity with endovascular procedures.

A Retrospective Analysis of Comparison of General Versus Regional Anaesthesia for Endovascular Repair of Abdominal Aortic Aneurysm

OBJECTIVE

The aim of this study is to compare general anaesthesia (GA) versus regional anaesthesia (RA) for endovascular aneurysm repair (EVAR).

METHODS

We analysed the files of 89 patients between August 2010-August 2012 who underwent elective EVAR retrospectively.

RESULTS

We performed RA for 32 patients (36%) and GA for 57 patients (64%). The operations were completed successfully in both groups and did not require conventional surgery. The mean age of the patients was 71.5±7 (range 50-88 years). RA was preferred more than GA in the presence of advanced-stage chronic obstructive pulmonary disease statistically (p=0.032). The usage of vasodilator drug and atropine was found to be higher in the GA group than the RA group in the intraoperative period (p=0.001 and p=0.01, respectively). The intensive care unit (ICU) was necessary for 5 patients in the RA group (16%) and 13 patients for the GA group (23%) postoperatively (p=0.301). The median ICU stay in the RA group was 2 hours and 4.4 hours in the GA group (p=0.114). The median hospital stay was 2.63±1.91 days in the RA group and 2.04±1.16 days in the GA group, with no statistically significant difference between groups (p=0.120). There was no mortality of patients in either group for the peroperative period and the 30-day follow-up period.

CONCLUSION

Our present study suggests that patient characteristics are more important than the anaesthetic method on the outcomes of EVAR.

Endovascular abdominal aortic aneurysm repair: surveillance of endoleak using maximum transverse diameter of aorta on non-enhanced CT

BACKGROUND

Repeat volumetric analysis of abdominal aortic aneurysm (AAA) after endovascular AAA repair (EVAR) is time-consuming and requires advanced processing, dedicated equipment, and skilled operators.

PURPOSE

To clarify the validity of measuring the maximal short-axis diameter (Dmax) of AAA in follow-up non-enhanced axial CT as a means of detecting substantial endoleaks after EVAR.

MATERIAL AND METHODS

CT images were retrospectively reviewed in 47 patients (7 women, 40 men; mean age, 76.2 years) who had no endoleak on initial contrast-enhanced CT after EVAR. Regular follow-up CT studies were performed every 6 months. At each CT study, the Dmax on the CT axial image was measured and compared with that on the last CT (115 data-sets). Contrast-enhanced CT was regarded as the standard of reference to decide the presence or absence of endoleaks. The appearance of endoleak was defined as the end point of this study.

RESULTS

Endoleaks were detected in 17 patients during the follow-up period. Mean Dmax changes for 6 months were significant between positive and negative endoleak cases (1.8 ± 1.9 vs. -1.1 ± 3.0 mm, P < 0.0001). When the Dmax change ≤ 0 mm for 6 months was used as the threshold for negative endoleak, the sensitivity, specificity, positive predictive value, and negative predictive value were 74.5, 82.4, 96.1, and 35.9%, respectively. When Dmax change ≤-1 mm was used as the threshold, the sensitivity, specificity, PPV, and NPV were 38.8, 100, 100, and 22.1%, respectively.

CONCLUSION

Contrast-enhanced CT is not required for the evaluation of endoleaks when the Dmax decreases by at least 1 mm over 6 months after EVAR.

Local anaesthesia for endovascular repair of infrarenal aortic aneurysms

OBJECTIVE

The study aimed to analyse and report the results of a 'local anaesthesia first' approach in elective endovascular aneurysm repair (EVAR) patients.

MATERIAL AND METHODS

Between January 2007 and August 2010, a total of 217 continuous patients (187 men, median age 76 years, range 52-94 years) underwent elective EVAR using this approach, with predefined exclusion criteria for local anaesthesia (LA). A retrospective analysis regarding technical feasibility, mortality, complication and endoleak rate was performed. The results are reported as an observational study.

RESULTS

LA was applied in 183 patients (84%), regional anaesthesia (RA) in nine patients (4%) and general anaesthesia (GA) in 25 patients (12%). Anaesthetic conversion from LA to GA was necessary in 14 patients (7.6%). Airway obstruction (n = 4) and persistent coughing (n = 3) were the most common causes for conversion to GA. Thirty-day mortality in the LA group was 2.7%, with 16/183 patients (8.7%) experiencing postoperative complications. All type I endoleaks (n = 5, 2.7%) occurred in patients with LA and challenging aneurysm morphologies.

CONCLUSIONS

A 'local anaesthesia first' strategy can successfully be applied in 75% of patients undergoing EVAR. The use of LA can impact imaging quality and thus precise endograft placement, which should be considered in patients with challenging aneurysm morphologies.

Anesthetic Experience With Endovascular Aortic Aneurysm Repair

Background: We endeavored to characterize the anesthesia experience with endovascular aneurysm repair (EVAR) at a large academic medical center in the United States. Methods: A retrospective review of electronic medical records was conducted for all patients undergoing elective EVAR from 2002 to 2007 in a large academic medical center. Results: A total of 522 cases met inclusion criteria, with 4% of cases using general anesthesia (GA), 92% regional anesthesia (RA), and 4% local anesthesia (LA). There was no statistically significant difference between the groups for duration of surgery or in-hospital mortality. In-hospital length of stay was longer for GA than LA or RA. Four cases were converted to open repair. Two mortalities occurred during the perioperative period (0.4% of cases). Conclusions: The vast majority of EVAR were successfully performed under RA, involved mild blood loss, involved infrequent need for conversion to GA, and resulted in brief in-hospital length of stay and low mortality rate.

Size of the proximal neck in AAAs treated with balloon-expandable stent-grafts: CTA findings in mid- to long-term follow-up

PURPOSE

To determine the evolution of the proximal aortic neck diameter in mid- to long-term follow-up after endovascular aneurysm repair of abdominal aortic aneurysm (AAA) with a balloon-expandable stent-graft.

METHODS

Thirty patients (27 men; average age 71 years, range 56-87) with infrarenal AAAs were treated with the SETA-Latecba balloon-expandable stent-graft (6 aortomonoiliac and 24 bifurcated configurations). Follow-up ranged from 4 to 8 years (mean 73.4 months). Computed tomography was done systematically before the procedure, after implantation (1-3 months), at 1 year, and annually thereafter. The last follow-up scan was utilized to measure the proximal neck for purposes of comparison with baseline and the initial post-implant scans.

RESULTS

Five patients died during follow-up of causes unrelated to the procedure. No endoleaks or graft migrations were observed. The pre-deployment proximal neck diameter (a) averaged 23.4 mm (range 18-32), the diameter after deployment of the stent-graft (b) averaged 24.9 mm (range 18-34), and the most recent follow-up proximal neck measurement (c) averaged 23.8 mm (range 18-31). Comparing the last follow-up to the post-implant measurements (c-b), the neck diameter decreased in 15 (50%) patients [7 with short necks (i.e., <15 mm)] and remained unchanged (no variation) in 15 (50%) patients (4 with short necks). All patients treated with the SETA-Latecba balloon-expandable stent-graft showed stability of the proximal aortic neck diameter in mid- to long-term follow-up.

CONCLUSION

The study showed that the diameter reached at initial deployment did not increase further in the long term, which supports the safety and reliability of this modular balloon-expandable stent-graft and illustrates that this device does not produce dilatation of the proximal neck after deployment. Future dilatation of the aortic neck is unlikely, and consequently, migration or delayed type I endoleak are also unlikely.

Effects of study design and trends for EVAR versus OSR

Purpose:

To investigate if study design factors such as randomization, multi-center versus single center evidence, institutional surgical volume, and patient selection affect the outcomes for endovascular repair (EVAR) versus open surgical repair (OSR). Finally, we investigate trends over time in EVAR versus OSR outcomes.

Methods:

Search strategies for comparative studies were performed individually for: OVID’s MEDLINE, EMBASE, CINAHL, HAPI, and Evidence Based Medicine (EBM) Reviews (including Cochrane DSR, ACP Journal Club, DARE and CCTR), limited to 1990 and November 2006.

Results:

Identified literature: 84 comparative studies pertaining to 57,645 patients. These include 4 randomized controlled trials (RCTs), plus 2 RCTs with long-term follow-up. The other 78 comparative studies were nonrandomized with 75 reporting perioperative outcomes, of which 16 were multi-center, and 59 single-center studies. Of the single-center studies 31 were low-volume and 28 were high-volume centers. In addition, 5 studies had all patients anatomically eligible for EVAR, and 8 studies included high-risk patients only. Finally, 25 long term observational studies reported outcomes up to 3 years.

Outcomes:

Lower perioperative mortality and rates of complications for EVAR versus OSR varied across study designs and patient populations. EVAR adverse outcomes have decreased in recent times.

Conclusion:

EVAR highlights the problem of performing meta-analysis when the experience evolves over time.

A review of the in vivo and in vitro biomechanical behavior and performance of postoperative abdominal aortic aneurysms and implanted stent-grafts

Endovascular repair of abdominal aortic aneurysms has generated widespread interest since the procedure was first introduced two decades ago. It is frequently performed in patients who suffer from substantial comorbidities that may render them unsuitable for traditional open surgical repair. Although this minimally invasive technique substantially reduces operative risk, recovery time, and anesthesia usage in these patients, the endovascular method has been prone to a number of failure mechanisms not encountered with the open surgical method. Based on long-term results of second- and third-generation devices that are currently becoming available, this study sought to identify the most serious failure mechanisms, which may have a starting point in the morphological changes in the aneurysm and stent-graft. To investigate the "behavior" of the aneurysm after stent-graft repair, i.e., how its length, angulation, and diameter change, we utilized state-of-the-art ex vivo methods, which researchers worldwide are now using to recreate these failure modes.

Hybrid procedures as a combined endovascular and open approach for pararenal and thoracoabdominal aortic pathologies

OBJECTIVES

to report our experience with hybrid vascular procedures in patients with pararenal and thoracoabdominal aortic pathologies.

METHODS

68 patients were treated for thoracoabdominal aortic pathologies between October 1999 and February 2004; 19 patients (16 men; mean age 68, range 40-79) with high risk for open thoracoabdominal repair were considered to be candidates for combined endovascular and open repair. Aortic pathologies included five thoracoabdominal Crawford I aneurysms, one postdissection expanding aneurysm, three symptomatic plaque ruptures (Crawford IV), five combined thoracic descending and infrarenal aneurysms with a healthy visceral segment, three juxtarenal or para-anastomotic aneurysms, and two patients with simultaneous open aortic arch replacement and a rendezvous maneuver for thoracic endografting. Commercially available endografts were implanted with standardized endovascular techniques after revascularization of visceral and renal arteries.

RESULTS

Technical success was 95%. One patient developed a proximal type I endoleak after chronic expanding type B dissection and currently is waiting conversion. Nine patients underwent elective, five emergency and five urgent (within 24 h) repair. 17 operations were performed simultaneously, and 2 as a staged procedure. Postoperative complications include two retroperitoneal hemorrhages, and one patient required long-term ventilation with preexisting subglottic tracheal stenosis. Thirty-day mortality was 17% (one multiple organ failure, one secondary rupture after open aortic arch repair, one myocardial infarction). Paraplegia or acute renal failure were not observed. Total survival rate was to 83% with a mean follow-up of 30 months.

CONCLUSIONS

Midterm results of combined endovascular and open procedures in the thoracoabdominal aorta are encouraging in selected high risk patients. Staged interventions may reduce morbidity.

Risk-Adapted Outcome After Endovascular Aortic Aneurysm Repair:Analysis of Anesthesia Types Based on EUROSTAR Data

PURPOSE

To compare anesthesia techniques in high-risk versus low-risk patients treated with endovascular aortic aneurysm repair (EVAR) with respect to outcomes.

METHODS

From July 1997 to August 2004, 5557 patients were enrolled in the EUROSTAR registry by 164 centers. Low-risk and high-risk patients were each divided into 3 groups according to anesthesia used during operation [general (GA), regional (RA), and local (LA)], resulting in 6 groups. Differences in preoperative and operative details among the 3 types of anesthesia were analyzed using a chi-square test for discrete variables and the Kruskal-Wallis test for continuous variables for each risk profile. Multivariate logistic regression analysis was performed on early complications.

RESULTS

Intensive care unit (ICU) admission was less frequent for high-LA (1.2% of patients) than high-RA (7.8%, p=0.0071) and high-GA (16.2%, p<0.0001), but high-RA still had a distinct advantage (p<0.0001) over high-GA. Systemic complications were lower both for high-LA (9.0%, p=0.0128) and for high-RA (10.7%, p<0.0001) than for high-GA (18.3%). Early death (< or =30 days) was reduced in high-RA (3.0%) versus high-GA (4.3%, p=0.0286).

CONCLUSION

On the basis of the EUROSTAR data, high-risk patients in particular attain important advantages from minimally invasive anesthetic techniques. Mortality, morbidity, hospital stay, and ICU admission are significantly lower for locoregional versus general anesthesia in the EUROSTAR registry. These results should encourage greater use of regional anesthesia in high-risk patients. Local anesthesia seems to be of similar benefit for EVAR in high-risk patients.

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.

Conversion to Open Repair After Endografting for Abdominal Aortic Aneurysm: Causes, Incidence and Results

OBJECTIVE

To evaluate frequency, causes and results of conversion to Open repair (OR) after endovascular repair (EVAR) in a single centre during an 8-year period.

DESIGN

Six hundred and forty-nine consecutive patients undergoing EVAR were followed up prospectively for endograft-related complications.

OUTCOMES

Early conversion was any OR during or within 30 days from the primary EVAR. Late conversion was any OR with removal of the endograft after 30 days since a completed EVAR procedure.

RESULTS

Median patient follow-up was 38 months (1-93 months). Conversion to OR was performed in 38 patients; nine early and 29 late. Most (7/9) early conversions were due to extensive vessel calcification. Peri-operative mortality was 22% (2/9). Late conversions occurred at a median of 33 months after primary EVAR: 29 were elective and 4 urgent. During the same interval, 79 secondary endovascular interventions were performed, 7 of which failed. The risk of conversion to OR was 9% at 6 years. At multivariate logistic regression analysis, no single factor (short, large or angulated neck, suprarenal fixation, large pre-operative diameter, iliac aneurysms, ASA score risk) was associated with the risk of late failure requiring conversion to OR.

CONCLUSION

The risk of death after early conversion should be recognized, to avoid forcing morphological indications for primary EVAR. Occurrence of late conversion after EVAR is not negligible, affecting almost 1 out of 10 patients after 6 years. In the presence of an expanding aneurysm after EVAR, especially after a failed secondary endovascular correction, an aggressive attitude in fit patients allows outcomes at similar to those of primary OR.

Surgical Conversion of Abdominal Aortic Stent-grafts—Outcome and Technical Considerations

OBJECTIVE

The purpose of this study was to evaluate the outcome of patients with stented abdominal aortic aneurysms who had to undergo open aneurysm repair with partial or total stent-graft removal.

METHODS

Between October 1996 and December 2003, 117 patients with abdominal aortic aneurysms underwent endovascular repair. When open surgery was necessary during the initial and same anaesthesia as stent-graft implantation, it was defined as immediate conversion. When conversion was performed during a second anaesthesia, we defined it as late (acute or elective) conversion.

RESULTS

A total of 33 patients underwent conversion to open surgery. In 7 (6%) patients, immediate conversion was necessary due to stent-graft misplacement and obstruction of the renal arteries (n=4), type Ia endoleaks (n=2) and stent-graft dislocation into the aneurysm sac (n=1). During a mean follow-up period of 39.6 months (min 0.03 months, max 80.4 months), 26 (23.6%) of the remaining 110 patients underwent late conversion to open surgery for endoleak (n=12), rupture (n=6), thrombosis (n=4), graft fatigue (n=2), aorto-duodenal fistula (n=1), and recurring peripheral embolisms (n=1). The mortality of acute conversion was 38% (5 of 13). Elective conversion did not lead to any mortality.

CONCLUSION

Acute conversion of stented abdominal aortic aneurysms is associated with a high mortality. Elective stent-graft explantation with open aortic reconstruction is a safe but complex procedure.

Detection of endograft fractures with multidetector row computed tomography

Delayed endograft metallic strut failures detected in vivo with multidetector row computed tomography (MDCT) are reported in two patients who underwent endovascular abdominal aortic aneurysm repair with AneuRx and Talent endografts. In both instances, nitinol fractures were associated with proximal migration and type I endoleak. In both cases, the metallic strut fractures were detected with transverse sections from 16-channel MDCT angiograms and confirmed by using volume rendering. These cases highlight the previously unreported ability of thin-section, high-resolution MDCT angiography to detect endograft strut fractures.

Endovascular Repair of Abdominal Aortic Aneurysms: Analysis of Aneurysm Volumetric Changes at Mid-Term Follow-Up

PURPOSE

To evaluate the volumetric changes in abdominal aortic aneurysms (AAA) after endovascular AAA repair (EVAR) in 24 months of follow-up.

METHODS

We evaluated the volume modifications in 63 consecutive patients after EVAR. All patients underwent strict duplex ultrasound and computed tomography angiography (CTA) follow-up; when complications were suspected, digital subtraction angiography was also performed. CTA datasets at 1, 6, 12, and 24 months were post-processed through semiautomatic segmentation, to isolate the aneurysmal sac and calculate its volume. Maximum transverse diameters (Dmax) were also obtained in the true axial plane, Presence and type of endoleak (EL) were recorded. A statistical analysis was performed to assess the degree of volume change, correlation with diameter modifications, and significance of the volume increase with respect to ELs.

RESULTS

Mean reconstruction time was 7 min. Mean volume reduction rates were 6.5%, 8%, and 9.6% at 6, 12, and 24 months follow-up, respectively. Mean Dmax reduction rates were 4.2%, 6.7%, and 12%; correlation with volumes was poor (r = 0.73-0.81). ELs were found in 19 patients and were more frequent (p = 0.04) in patients with higher preprocedural Dmax, The accuracies of volume changes in predicting ELs ranged between 74.6% and 84.1% and were higher than those of Dmax modifications. The strongest independent predictor of EL was a volume change at 6 months < or = 0.3% (p = 0.005), although 6 of 19 (32%) patients with EL showed no significant AAA enlargement, whereas in 6 of 44 (14%) patients without EL the aneurysm enlarged.

CONCLUSION

The lack of volume decrease in the aneurysm of at least 0.3% at 6 months follow-up indicates the need for closer surveillance, and has a higher predictive accuracy for an endoleak than Dmax.

Treatment of Abdominal Aortic Aneurysms With an Endovascular Stent-Graft Prosthesis in 96 High-Risk Patients

. Ninety-six patients, mean age 72 +/- 8 years, with an abdominal aortic aneurysm (AAA) and significant comorbidities with a vascular anatomy favorable for supporting an endovascular prosthesis underwent endovascular repair of the AAA. The 90-day survival was 100%. The incidence of endoleaks at 25-month mean follow up was 4 of 96 patients (4%). None of the 96 patients (0%) required surgical conversion of the AAA. At 14-month mean follow up after endovascular repair, the diameter of the AAA was significantly reduced from 6.2 +/- 1.2 cm to 5.0 +/- 1.1 cm (P < 0.001).

Complications of major aortic and lower extremity vascular surgery

Atheromatous disease and invasive intervention of the aortoiliac and distal arteries are common. Morbidity and mortality have been reduced through understanding and management of patient risk factors. Complications of this form of treatment affect all organ systems; mortality is most frequently caused by a cardiovascular complication (eg, myocardial infarction). Infection, leading to aortoenteric fistula is a dreaded complication, and paraplegia, though rare, is a devastating outcome. Multiorgan failure and death may result from a systemic inflammatory response syndrome. Vascular surgery for infrainguinal disease also has a significant cardiovascular complication rate. Resulting complications may affect all organs; loss of an extremity may occur. The first part of this article reviews perioperative and postoperative complications of open aortic repair and lower-extremity revascularization and addresses the issue of regional anesthesia for major vascular surgery. The second part reviews endovascular aortic repair (EVAR). EVAR is a new intervention that combines surgery and radiology. Complications of EVAR are similar to open repair, but early results suggest they may be less frequent. New technology leads to new complications; endoleaks, migration of the endoprosthesis, and surgical conversion are unique to EVAR. The benefits of EVAR may be less blood loss, shorter hospitalization, and less cardiovascular stress; the risks may be aneurysm recurrence, prolonged surveillance and repeated secondary procedures. The development of EVAR, the complications, and the anesthesia-related concerns of EVAR, including its use in management of acute abdominal aortic aneurysm are reviewed.

Outcome of endoleak following endoluminal abdominal aortic aneurysm repair

BACKGROUND

The most important complication of endoluminal abdominal aortic aneurysm repair is endoleak, in which there is persistent blood flow outside the graft but within the aneurysm sac. Depending on endoleak type, there is an ongoing potential for aneurysm expansion or rupture. Conversely, some endoleaks may resolve spontaneously. Absolute indications for interventional management of endoleaks remain elusive due to the heterogeneous nature of leaks and uncertainty in predicting their outcome.

METHODS

A retrospective review was conducted on all endoluminal graft recipients with endoleaks at Repatriation General Hospital over a 3-year period. Data were collected via a database maintained by the Department of Vascular Surgery, and hospital casenotes.

RESULTS

Sixty-six patients underwent endoluminal graft insertion in the study period. Fourteen endoleaks were observed in 11 patients, representing an endoleak rate of 21.2%. There were three type I leaks and 11 type II leaks. One type I leak resolved spontaneously, one resolved immediately following interventional management, and one resolved 6 months after interventional management. Interventional treatment was undertaken in seven cases of type II leak due to increase in aneurysm diameter by 5 mm. Two type II endoleaks resolved spontaneously. Aneurysm diameter increased in two patients following radiographic resolution of their endoleaks. There were no cases of aneurysm rupture.

CONCLUSIONS

Initial observation is a reasonable management option in most cases of type II endoleak, because some will spontaneously resolve during follow up. Those associated with increase in aneurysm size should undergo interventional treatment. Conservative management of type I endoleaks may be undertaken in extreme isolated cases.

Recognition of an Infected Endoluminal Aortic Prosthesis Following Repair of Abdominal Aortic Aneurysm: Case Report and Review of the Literature

Presentation of an infected endoaortic stent graft may be different from those with open aortic reconstruction and may be difficult to recognize. We report a case of an infected endoaortic stent graft for treatment of an abdominal aortic aneurysm (AAA). In this case, clinically significant endograft infection was not apparent on the initial computed tomography (CT) scan, however, serial CT scans demonstrated progressive AAA enlargement with increased inflammation. The white blood cell scan documented enhancement throughout the infrarenal aorta. The patient's condition was managed with total explantation of the endograft, AAA resection, and reconstruction with a cryopreserved aortic homograft. This report reviews the presentation, radiographic findings, and diagnosis of as well as literature on infected endoaortic stent grafts.

Midterm outcome of endovascular abdominal aortic aneurysm repair in octogenarians: A single institution's experience

OBJECTIVES

We analyzed midterm durability of endovascular abdominal aortic aneurysm repair (EVAR) in octogenarians compared with younger patients.

METHODS

Data for 182 consecutive patients who underwent elective EVAR between 1999 and 2003 were retrospectively reviewed. Forty-nine patients (27%) were 80 years or older (study group [SG]; mean age, 84 years; range, 80-89 years), and 133 patients (73%) were younger (control group [CG]; mean age, 72 years; range, 53-79 years). Chi2 analysis, Fisher exact test, Student t test, and Mann-Whitney U test were used as appropriate to test for intergroup differences. Kaplan-Meier curves, log-rank tests, and multivariate Cox models were used for time-to-event analysis, with P < or =.05 considered significant.

RESULTS

Mean follow-up was 16 months (range, 1-43 months). Body weight was higher (P <.001), and elevated plasma lipid levels (59% vs 43%; P =.042) and use of nicotine (47% vs 29%; P =.015) more frequent in the octogenarians. Baseline aneurysm size, procedure-related data, and hospital stay were comparable between groups. Aneurysm-related mortality was 0% in the study group and 0.7% in the control group (P =.740). Systemic complications occurred in 22% (SG) versus 11% (CG) (P =.035), owing to a rise in serum creatinine concentration greater than 30% of baseline in 14% in the octogenarian group (vs 5% in the CG; P =.048). Groin lymphoceles developed in 12% (SG) versus 2% (CG; P =.013). Technical success was 96% (SG) versus 98% (CG; P =.408), and clinical success was 86% versus 90% (P =.269). No aneurysm rupture occurred during follow-up, and aneurysm-related adverse events were comparable between groups. The estimated risk for any type of endoleak (2.2; 95% confidence interval [CI], 1.1-4.2; P =.023) or type II endoleak (2.1; 95% CI, 1.0-4.3; P = 0.51) was higher in the study group versus the control group; however, this did not affect secondary procedure rates (SG 16% vs CG 12%; estimated risk, SG vs CG,: 1.5; 95% CI, 0.6-3.6; P = 0.420) or aneurysm remodeling (97.2% combined aneurysm sac stabilization or decrease in both groups; P =.592). Aneurysm enlargement occurred in 2.8% (SG 1 vs CG 4; P =.592).

CONCLUSION

Elective EVAR in octogenarians appears safe and effective over midterm follow-up, with a temporary decrease in renal function (14%) and postoperative lymphoceles (12%) being the most common postoperative adverse events. Advanced chronologic age is not associated with diminished procedural outcome, clinical success, or postoperative survival, compared with younger age. Because of low perioperative mortality and high procedural success, EVAR may be the preferred approach to abdominal aortic aneurysm treatment in selected elderly patients.

The utility of commercially available endografts in the treatment of contained ruptured abdominal aortic aneurysm with hemodynamic stability

PURPOSE

Food and Drug Administration-approved endografts are suitable for the elective repair of abdominal aortic aneurysms (AAAs) with favorable aneurysm anatomy. Our aim is to illustrate the feasibility and versatility of commercially available endografts for emergency AAA repair in hemodynamically stable AAA rupture.

METHODS

From June 2001 to July 2002, five patients presented with severe abdominal pain and were diagnosed with contained rupture of an infrarenal AAA. In all cases, patients were deemed unfit to withstand conventional open repair by both the referring outside medical center as well as our center's team. All patients were hemodynamically stable on arrival at our medical center. Measurement and selection of endovascular devices were based on computed tomography (CT) scans performed emergently at the outside referring center. The required emergently procured endografts were obtained within 2 to 4.5 hours (mean, 3.1 hours) of presentation. Complex anatomy at the proximal and distal fixation zones or difficult access was present in every case.

RESULTS

All patients survived endograft repair and had successful exclusion of their aneurysm sac on the basis of intraoperative arteriography and postoperative CT surveillance. All were discharged to home at baseline function within a mean of 6.8 days (range, 2-13 days). There were no deaths. There was one postoperative pulmonary embolism, one myocardial infarct, and one type 2 endoleak. Mean operative time and blood loss were 4.67 hours and 217 mL, respectively. At a mean follow-up of 18 months, CT scans showed stable or shrinking aneurysm sacs.

CONCLUSIONS

In patients with contained ruptured AAAs who present with hemodynamic stability and comorbidities that preclude open surgery, commercially available endografts are a versatile treatment option even in the face of complicated aneurysm anatomy.

Cumulative sum failure analysis of the learning curve with endovascular abdominal aortic aneurysm repair

PURPOSE

The purpose of this study was to evaluate the importance of experience and the learning curve with endovascular abdominal aortic aneurysm (AAA) repair.

METHODS

A retrospective analysis was performed of all elective endovascular AAA repairs attempted by an individual surgeon and radiologist over a 4-year period. The primary outcome variable was achievement and 30-day maintenance of initial clinical success as defined by the Society for Vascular Surgery/American Association of Vascular Surgery reporting standards. Following standard statistical analysis, the cumulative sum (CUSUM) method was used to analyze the learning curve, with a predetermined acceptable failure rate of 10% and calculated 80% alert and 95% alarm lines.

RESULTS

Ninety-six elective endovascular AAA repairs were attempted by this team between 1998 and 2002 (mean age 74 +/- 0.8 years; mean aneurysm diameter 5.98 +/- 0.8 cm). Initial clinical success was achieved and maintained in 85 of 96 patients (88.5%). Although results were acceptable throughout the study period, improved results with respect to the target failure rate (10%) were not achieved until 60 patients were treated. The learning or CUSUM curves did not differ for different device manufacturers, with improved results being achieved following 20 implantations of each device. The results did differ when comparing aortouniiliac grafts (n = 27) and bifurcated grafts (n = 64). Results with bifurcated grafts remained consistent throughout the study period, whereas with aortouniiliac grafts, results improved after only a few procedures in comparison with the target failure rate.

CONCLUSION

Success rates with endovascular aneurysm repair will improve with an individual's experience. The CUSUM method is a valuable tool in the evaluation of this learning curve, which has credentialing and training implications. Although acceptable results were obtained throughout the study period, this analysis indicates that 60 endovascular aneurysm repairs, or 20 with an individual device, are necessary before optimal rates of initial clinical success can be achieved. These results can be achieved more readily with aortouniiliac grafts than with bifurcated grafts.

Decision-making in follow-up after endovascular aneurysm repair based on diameter and volume measurements: a blinded comparison

OBJECTIVE

to assess whether volume, in addition to diameter, measurements facilitate decision-making after endovascular aneurysm repair (EVAR).

MATERIAL/METHODS

patients (n = 82) with an immediately post-EVAR, and at least one follow-up (3-60 months), computed tomographic angiogram (CTA) were studied. The actual and all preceding proportional sac size changes were recorded. The resulting 347 diameter and 347 volume data were placed in random order and reviewed by three blinded observers who then recommended one of three treatment policies: "good/wait", "uncertain/intensify follow-up" or "not good/further diagnostics (Dx) or intervention (Rx)". The observers were instructed to consider changes of 10% relevant. One observer reviewed the graphs twice.

RESULTS

the interobserver agreements (kappa) for the diameter were 0.92, 0.81 and 0.76 and for volumes 0.91, 0.88 and 0.86. The intra-observer agreement was 0.93 for both diameter and volume. Volume data resulted in significantly more "good/wait" decisions out to 36 months. Diameter data resulted in more "not good/Dx or Rx"-decisions out to 36 months (all p < 50.005).

CONCLUSION

post-EVAR aneurysm sac volume data appears to provide earlier reassurance, reduce unnecessary interventions and to be more sensitive to secondary problems than diameter data alone.

Endovascular repair of ruptured abdominal aortic aneurysms: logistics and short-term results

PURPOSE

To report our experience in establishing a treatment protocol for endovascular aneurysm repair (EVAR) of ruptured abdominal aortic aneurysms (rAAA), including an investigation of the reasons for patient exclusion and a report of our short-term results.

METHODS

Between 1997 and July 2002, 21 patients with rAAA underwent endovascular repair according to our protocol and were followed prospectively. A retrospective analysis was also conducted of 23 rAAA patients treated with open repair from January 2001 through June 2002. Procedural and clinical data from this sample were compared to 14 contemporaneous emergent EVAR cases and analyzed to determine why the open repair patients were not treated with an endovascular approach.

RESULTS

Among the 21 patients treated with emergent EVAR since the beginning of this protocol, 6 (29%) procedures were performed under local anesthesia and 6 were performed percutaneously. Thirty-day mortality was 19%. In the comparison of 14 emergent EVAR cases to 23 open rAAA repairs, the mean duration of symptoms prior to intervention was 12 hours for the EVAR patients and <1 hour for OR patients. No significant difference was found in operating time, but the EVAR group had significantly less blood loss (p=0.0001) and transfusion needs (p=0.02); duration of intensive care unit stay was significantly shorter in the EVAR group (p=0.02). Thirty-day mortality was 29% (4/14) for EVAR and 35% for OR (8/23) (p>0.05). Reasons for not performing EVAR were unavailability of adequate equipment (n=11) or trained staff (n=7), hemodynamically unstable patient (n=2), mycotic aneurysm (n=2), and unfavorable anatomy in a 60-year old patient with a <5-mm-long, sharply angled infrarenal neck.

CONCLUSIONS

Endovascular repair of ruptured aortic aneurysms is feasible, and short-term results are promising. Good logistics, adequate training of physicians and staff in an elective setting, and versatile endografts are prerequisites for this type of treatment program.

Abdominal aortic aneurysm size regression after endovascular repair is endograft dependent

OBJECTIVE

This study was performed to determine whether abdominal aortic aneurysm (AAA) regression is different with various endografts after endovascular repair.

METHODS

A four-center retrospective review of size change after endovascular AAA repair was performed. Consecutive patients with at least 1-year follow-up and available imaging studies were included. Three hundred ninety patients received either the Ancure, AneuRx, Excluder, or Talent endograft. AAA size and endoleak status were recorded from computed tomography (CT) scans at the initial postoperative follow-up visit and at 1 and 2 years thereafter. AAA size was defined as the minor axis of the infrarenal aorta on the largest axial section on the two-dimensional CT scan. A change in AAA size of 0.5 cm or greater from baseline was considered clinically significant. The effect of initial size, endoleak, and type of endograft on AAA regression was analyzed.

RESULTS

Mean baseline size was significantly greater with Talent endografts and smaller with Excluder endografts. Clinically significant regression in AAA size occurred in nearly three fourths of patients with Ancure and Talent endografts at 2 years. Regression in AAA size was less frequent with the AneuRx (46%) and Excluder (44%) devices. Initial size, endoleak, and endograft type were significant predictors of regression at multivariate analysis at 1 year. However, by 2 years only endograft type was still an independent predictor of AAA shrinkage.

CONCLUSIONS

Long-term morphologic changes after endovascular aneurysm repair depend on endograft type.