Influence of abdominal aortic aneurysm size on the feasibility of endovascular repair

Morphology-Related Limitations of Endovascular Aneurysm Repair Applicability in the Treatment of Abdominal Aortic Aneurysm in West-Central Poland

BACKGROUND

Morphology is one of the most important factors influencing the long-term durability of endovascular repair of an infrarenal abdominal aortic aneurysm (AAA). The knowledge of morphological characteristics of AAA that may differ in various populations seems to be important for further development of a technology of endovascular repair as well as for planning of treatment strategies. To analyze the current applicability of endovascular aneurysm repair (EVAR) in patients with an infrarenal AAA with an indication for elective treatment in west-central Poland.

METHODS

Computed tomography angiograms of 100 consecutive patients with infrarenal AAA deemed to require treatment were analyzed with an OsiriX DICOM viewer in 3D-multiplanar reconstruction mode. Proximal neck diameter, length, angulation, shape, the presence of thrombus and calcification, distal neck diameter, and morphology of the iliac arteries were determined. Three sets of morphological criteria were established. The optimal criteria consisted of a nonconical proximal neck without moderate or severe calcification or thrombus, with a diameter of 18-28 mm, length of ≥15 mm, and β angulation of <60%; a distal neck with a diameter of ≥20 mm; a landing zone in the common iliac arteries (CIAs) with a length of ≥10 mm and diameter of ≤20 mm; and external iliac arteries with diameters of ≥7 mm. The suboptimal criteria included proximal neck diameters of 18-32 mm, neck lengths ≥10 mm, infrarenal neck angulations of up to 75°, and CIA diameters of up to 25 mm. Finally, the extended suboptimal criteria included proximal neck diameters of 16-34 mm and infrarenal neck angulations ≤90°, without limits in the maximal diameter of the CIAs.

RESULTS

The median maximum aneurysm diameter was 61 mm. The optimal, suboptimal, and extended suboptimal criteria were met by 23%, 32%, and 53% of patients, respectively. The most common deviations were wide, conical, and angulated proximal necks and aneurysmal iliac arteries.

CONCLUSIONS

The majority of patients with AAA deemed to be candidates for elective repair do not meet the most favorable criteria for EVAR. Availability of better endovascular solutions for conical, angulated, and wide necks and aneurysmal iliac arteries would likely expand EVAR applicability. Open repair remains a valid option.

Effect of β-blocker on aneurysm sac behavior after endovascular abdominal aortic repair

OBJECTIVE

This study was conducted to determine whether β-blocker (BB) therapy is associated with abdominal aortic aneurysm (AAA) sac regression after endovascular abdominal aortic repair (EVAR).

METHODS

A total of 198 patients (mean age, 76 years) who underwent EVAR were analyzed (104 in the BB group and 94 in the non-BB group). The primary end point was the incidence of AAA sac regression at 1 and 2 years.

RESULTS

Hypertension, coronary artery disease, and hyperlipidemia were more common in the BB group. The BB group was also more likely to have been prescribed an aspirin and a statin than the non-BB group. The length of proximal neck was significantly longer in the non-BB group than in the BB group. All study patients were monitored for at least 1 year after EVAR, and 2-year follow-up was available in 104 patients (52.5%). There was no statistically significant difference in the incidence of aneurysm sac regression in either group at 1 year (52.1% in the non-BB group vs 45.2% in the BB group; P = .330) and 2 years (58.5% in the non-BB group vs 64.7% in the BB group; P = .515). The difference of the change of AAA maximum diameter between two groups did not reach statistical significance at 1 year (-6.0 ± 7.0 mm in the non-BB group vs -5.5 ± 8.1 mm in the BB group; P = .644) and 2 years (-9.0 ± 10.5 mm in the non-BB group vs -9.0 ± 10.0 mm in the BB group; P = .977). BB therapy was not associated with increased odds of AAA sac regression. The effect of third-generation BBs on AAA sac regression was not significant.

CONCLUSIONS

BB therapy had no effect on AAA sac regression. At the present time, there is insufficient evidence to recommend BB therapy for the purpose of AAA sac regression.

Endovascular Repair of Small Abdominal Aortic Aneurysms: A Paradigm Shift?

Recent reports have documented poor long-term results following endovascular aneurysm repair (EVAR) of large abdominal aortic aneurysms (AAA). EVAR of small AAAs may result in improved long-term results compared to large AAAs. It is not known whether the frequency of anatomic suitability for EVAR is increased for small compared to large AAAs. This study compared the anatomic suitability of large and small AAAs for EVAR in an unselected patient population. Radiology reports for all computed tomography (CT) scans in a single hospital over a recent 3-year period were reviewed. AAAs diagnosed by contrasted CT scans with cuts >7 mm were excluded. Suitability for EVAR was determined by neck diameter, length, and angulation. In addition, iliac diameters and common iliac distal landing zone lengths were determined. Computerized 3-dimensional (3D) reconstruction was used to measure neck angulation and total aortic tortuosity. One hundred ninety-one patients were found to have AAAs with adequate CT scans for evaluation. Suitability for EVAR was highest in patients with AAA diameters of 3–4 cm and declined with increasing size of the AAA. Dividing AAAs into sizes greater than or less than 5.5 cm revealed that small AAAs had significantly longer necks, less neck angulation, longer common iliac landing zones, and less total aortic tortuosity. Multivariable analysis revealed that maximal aortic diameter was the only independent predictor of suitability for EVAR (p = 0.005, odds ratio 1.67, CI 95% = 1.17 to 2.38). The odds ratio predicts that with each 1 cm increase in size, the likelihood of suitability decreased by 5.3-fold. Small AAAs have less complex anatomy with longer aortic necks, less neck angulation, and less tortuosity. The poor outcomes following the treatment of large AAAs is thought to be due to complex anatomy. EVAR of less anatomically challenging small AAAs may improve longterm outcomes.

Endovascular vs Open AAA Repair: Does Size Matter?

Since the natural tendency of the aorta is to increase in diameter and tortuosity with age and since abdominal aortic aneurysms (AAAs) increase in diameter and length over time, encroaching on the renal and hypogastric orifices, early repair of AAAs (when =4.0 cm) may allow greater applicability of the endovascular option because of more favorable aortoiliac morphology. Patients who present at an older age with larger AAAs should be more likely to be anatomically excluded from endovascular AAA repair. Over a 42-month period, 317 consecutive patients referred with aortoiliac aneurysms (infrarenal AAA =4.0 cm) were evaluated by one of the authors (SGL) for endovascular vs open repair based on computed tomography (CT) and angiographic imaging. The 10 anatomic exclusion criteria were those applicable to the Zenith ® endograft (Cook, Inc), which currently is the most anatomically inclusive of the aortic endografts in commercial use in the United States. Based on their aortoiliac morphology, 212 patients were excluded from endovascular repair and 105 were included as acceptable anatomic candidates. Age, AAA size, and the reason(s) for exclusion were recorded for each patient. By use of Student's t test and logistic and linear regression analyses, the groups were compared by age, AAA size, and age + size. There was no significant difference in patient age or AAA size distribution between the group of patients excluded from endovascular repair based on aortoiliac morphology compared to those who met the inclusion criteria. Patients with small AAAs (4.0–5.4 cm) had similar age distribution as those with large (=5.5 cm) AAAs. The majority of patients (87%) were excluded based on proximal aortic neck morphology. The presence of aortoiliac morphology that precludes endovascular repair is independent of patient age or AAA size at presentation. A patient presenting with a small (4.0–5.4 cm) AAA is not more likely to be a candidate for endovascular repair than a patient with a large AAA.

Endoluminal Repair of Abdominal Aortic Aneurysms: Strengths and Weaknesses of Various Prostheses Observed in a 4.5-Year Experience

Purpose:

To summarize the results of endovascular abdominal aortic aneurysm (AAA) treatment using several endograft designs over a 4.5-year experience and offer comparisons on the various devices.

Methods:

From May 1992 to August 1996, 121 AAA patients meeting the criteria for an endoluminal repair were treated with 1 of 5 endograft designs in three configurations. The endografts were implanted in the operating room under fluoroscopic control. Follow-up included contrast-enhanced computed tomography within 10 days of operation, 6 months postoperatively, and annually thereafter.

Results:

Endografts were successfully deployed in 106 patients (88%). Fifteen cases were converted to open repair. Six procedure-related deaths occurred within 30 days owing to myocardial infarction (3), combined renal failure and septicemia (2), and multisystem failure (1). There were 36 local/vascular complications (30%) and 18 systemic/remote complications (15%). Of the 121 patients undergoing endoluminal AAA repair, 93 (77%) are currently alive and well with their AAAs excluded from the circulation.

Conclusions:

Trends in endoluminal AAA repair and prosthetic design point toward simpler devices and earlier treatment of smaller aneurysms once the long-term outcome of aortic endografting has been determined.

Should the size threshold for elective abdominal aortic aneurysm repair be lowered in the endovascular era? No

According to the current international guidelines, patients with infrarenal or juxtarenal abdominal aortic aneurysms (AAAs) measuring > or = 5.5 cm should undergo repair to reduce the risk of rupture. The 5.5-cm-diameter threshold is the size when the AAA rupture rate balances the mortality rates of elective open surgical AAA repair (3%). Endovascular AAA repair (EVAR) is associated with lower perioperative mortality and complication rates compared with open surgical repair. This debate addresses the issue whether the current size threshold for elective AAA repair needs to be lowered in the endovascular era. This article supports the position that the size threshold for AAA repair should not be lowered.

Fatores envolvidos na migração das endopróteses em pacientes submetidos ao tratamento endovascular do aneurisma da aorta abdominal

A migração da endoprótese é complicação do tratamento endovascular definida como deslocamento da ancoragem inicial. Para avaliação da migração, verifica-se a posição da endoprótese em relação a determinada região anatômica. Considerando o aneurisma da aorta abdominal infrarrenal, a área proximal de referência consiste na origem da artéria renal mais baixa e, na região distal, situa-se nas artérias ilíacas internas. Os pacientes deverão ser monitorizados por longos períodos, a fim de serem identificadas migrações, visto que estas ocorrem normalmente após 2 anos de implante. Para evitar migrações, forças mecânicas que propiciam fixação, determinadas por características dos dispositivos e incorporação da endoprótese, devem predominar sobre forças gravitacionais e hemodinâmicas que tendem a arrastar a prótese no sentido caudal. Angulação, extensão e diâmetro do colo, além da medida transversa do saco aneurismático, são importantes aspectos morfológicos do aneurisma relacionados à migração. Com relação à técnica, não se recomenda implante de endopróteses com sobredimensionamento excessivo (> 30%), por provocar dilatação do colo do aneurisma, além de dobras e vazamentos proximais que também contribuem para a migração. Por outro lado, endopróteses com mecanismos adicionais de fixação (ganchos, farpas e fixação suprarrenal) parecem apresentar menos migrações. O processo de incorporação das endopróteses ocorre parcialmente e parece não ser suficiente para impedir migrações tardias. Nesse sentido, estudos experimentais com endopróteses de maior porosidade e uso de substâncias que permitam maior fibroplasia e aderência da prótese à artéria vêm sendo realizados e parecem ser promissores. Esses aspectos serão discutidos nesta revisão.

Randomized clinical trials of endovascular repair versus surveillance for treatment of small abdominal aortic aneurysms

The Aneurysm Detection and Management (ADAM) trial and the United Kingdom Small Aneurysm Trial (UKSAT) demonstrated that early open surgical repair of small (<5.5 cm in diameter) abdominal aortic aneurysms (AAAs) conveyed no benefits compared with surveillance. In 2 randomized controlled trials (RTCs), operative mortality rates were significantly lower with endovascular aneurysm repair (EVAR) than with open surgery for treatment of large AAAs. Retrospective analyses of EVAR databases suggested that EVAR outcomes are directly related to aneurysm size and are better for smaller AAAs. It has thus seemed logical that a less invasive treatment strategy might be beneficial in treating patients with small AAAs. Two new RCTs have been initiated to evaluate early EVAR versus surveillance in patients with small AAAs. The European-based 17-site CAESAR (Comparison of surveillance vs Aortic Endografting for Small Aneurysm Repair) trial had enrolled 740 patients with small AAAs (4.1-5.4 cm) for surveillance or EVAR with the Zenith stent-graft. The primary endpoint of CAESAR is all-cause mortality at 54 months. The 70-site PIVOTAL (Positive Impact of endoVascular Options for Treating Aneurysm earLy) trial in the United States is enrolling up to 1025 patients with small AAAs (4-5 cm) for surveillance or EVAR with the AneuRx or Talent stent-grafts. The primary endpoints of PIVOTAL are aneurysm rupture and AAA-related deaths at up to 36 months after randomization. CAESAR and PIVOTAL should provide objective evidence to guide the use of EVAR for small AAAs.

The PIVOTAL study: a randomized comparison of endovascular repair versus surveillance in patients with smaller abdominal aortic aneurysms

The diameter of an abdominal aortic aneurysm (AAA) is the single most important factor in deciding whether to repair an aneurysm or to monitor it conservatively. Open surgical repair does not appear to be beneficial until the diameter of the aneurysm is >5.5 cm. Prospective clinical trials, however, confirmed a lower risk of operative mortality after endovascular aneurysm repair (EVAR) than after open surgical repair. Further, retrospective analyses of EVAR databases suggested that EVAR outcome is directly related to aneurysm size and is better for smaller aneurysms than for larger aneurysms. Noting similar results with open surgical management vs surveillance in patients with smaller AAA, lower morbidity rates with EVAR vs open repair, and the favorable results with EVAR in smaller aneurysms, a clinical trial testing the hypothesis that EVAR is beneficial in patients with small AAA appeared warranted. To answer this question, the 70-site Positive Impact of endoVascular Options for Treating Aneurysm earLy (PIVOTAL) was begun. PIVOTAL has an enrollment goal of up to 1025 patients with a 4- to 5-cm AAA, randomly assigning patients to EVAR or surveillance. The primary end points of PIVOTAL are aneurysm rupture and AAA-related death at up to 36 months after randomization. When complete, the results of PIVOTAL should provide objective evidence to guide the use of EVAR for small AAAs.

Endovascular Repair of Infrarenal Abdominal Aortic Aneurysms in High-Risk-Surgical Patients

PURPOSE

Following the publication of a prospective randomized trial (EVAR2) that questioned the benefit of endovascular repair of abdominal aortic aneurysms (AAA) for high-surgical-risk patients, we evaluated our own initial and long-term results with endovascular AAA repair for this patient population.

MATERIAL AND METHODS

Between January 2000 and December 2005, 115 patients with an AAA managed by an aortic endograft were entered in a registry. Data concerning diagnosis, operative risk, treatment, and follow-up were analyzed on an intention-to-treat basis for all patients considered to be poor candidates for surgery. Patients with a ruptured AAA and those who were good surgical candidates were excluded from analysis. The main goal was evaluation of the operative mortality and the long-term survival of these patients. Secondary goals were determination of the frequency of secondary operations, the outcome of the aneurysm sac, and primary and secondary patency rates after aortic endograft placement.

RESULTS

A total of 92 high-surgical-risk patients treated by an endograft were entered in this study. Sixty-seven patients (73%) were classed ASA III and 18 (20%) were ASA IV (20%). Mean aneurysm diameter was 58 mm+/-9 mm. The technical success rate was 99%. Operative mortality was 4.3% (4 cases). Four patients required re-intervention during the mean follow-up of 18 months. The survival rate at 3 yr was 85%. One type I endoleak (1%) and 9 type II endoleaks (9.7%) occurred during the follow-up period. Primary and secondary patency rates at 3 yr were respectively 96% and 100%.

CONCLUSION

Our initial and long-term results with endograft repair of AAA in high-surgical-risk patients were satisfactory. These results appear to justify endovascular repair for this patient population.

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.

Surveillance of small aortic aneurysms does not alter anatomic suitability for endovascular repair

OBJECTIVE

Small abdominal aortic aneurysms (AAAs; 4-5.4 cm) are more likely to be suitable for endovascular aneurysm repair (EVAR) than large aortic aneurysms (>5.5 cm). The purpose of this study was to determine whether small AAA growth is associated with the development of morphologic characteristics that decrease eligibility for EVAR.

METHODS

We studied 54 patients who underwent 2 or more computed tomography scans with 3-dimensional reconstruction during surveillance of small AAAs. Morphologic aortic aneurysm features and changes were measured according to Society for Vascular Surgery reporting standards. Suitability for EVAR was determined by neck anatomy (diameter, length, and angulations), iliac artery morphology, and total aortic aneurysm angulation and tortuosity.

RESULTS

The median age of the study cohort was 73 years (interquartile range [IQR], 65-77 years). The median follow-up period was 24 months (IQR, 15-36 months). The median small AAA diameter increased from 44.5 mm (IQR, 41-48 mm) to 48.9 mm (IQR, 45.7-52.0 mm). The median aortic neck diameter increased from 23.0 to 24.0 mm (P = .002), whereas median neck length decreased from 26.5 to 20.0 mm (P = .001). Aortic aneurysm median tortuosity index increased from 1.09 to 1.11 (P = .05). No significant changes in iliac artery morphology occurred. Overall, the anatomic suitability for endovascular repair did not significantly change during the study period (74% vs 69%; McNemar test; P = .25).

CONCLUSIONS

Changes in aortic morphology are frequently associated with small AAA growth at mid-term follow-up, but such changes are minor and do not affect overall anatomic suitability for EVAR. These data reveal that continued surveillance of small AAAs does not threaten the window of opportunity for EVAR.

Endovascular repair of abdominal aortic aneurysms: CTA evaluation of contraindications

Endovascular aortic aneurysm repair (EVAR) is considered an acceptable alternative to open surgery in selected patients. Its feasibility depends mainly on anatomic factors that represent the important predictors of success and the most important exclusion criteria. Poor anatomic patient selection is generally associated with a higher risk for procedural complications and compromised long-term outcomes. Therefore pretreatment imaging is crucial for evaluating patient suitability for EVAR. Multidetector computed tomographic angiography represents the current standard of reference in the evaluation of the abdominal aorta and iliac axis anatomy because it provides all the details needed for selection of patients who are suitable for endograft and the choice of the appropriate device. This report identifies and reviews computed tomographic angiographic anatomic contraindications for EVAR.

Minilaparotomy for Aortoiliac Aneurysmal Disease

Vascular surgery is evolving, as other specialities, toward minimally invasive techniques. Presently, 3 approaches to aortoiliac disease are suggested as minimally invasive. Besides the endovascular procedures, laparoscopic techniques and minilaparotomy are being advocated. Although for aneurysmal disease, we favor a totally laparoscopic approach, criticisms raised over laparoscopy-assisted techniques by those advocating minilaparotomy led us to investigate the benefits of the latter technique. We first evaluated the procedure in 7 patients with infrarenal abdominal aortic aneurysm (AAA). We found the procedure impossible to perform with an 8- to 10-cm incision in 6 of the 7 patients. This led us to evaluate causes of failure of the technique. It appeared to us that most of our complications were related to inadequate exposure. Fifty consecutive computed tomography scans from patients with AAA of surgical size were then reviewed to evaluate the aneurysm lengths and compare them to the reported lengths of skin incision for minilaparotomy. Results were expressed adding a total of 2 cm for proximal and distal clamping. Only 2% of patients would present with aneurysms suitable for treatment through an 8-cm midline incision and 30% through a 10-cm incision. We then reviewed the literature on minilaparotomy. We believe that minilaparotomy should be reserved for those patients with purely aortic disease and the appropriate body habitus.

Incidence of Renal Infarctions After Transrenal Stent Placement in an Animal Model

PURPOSE

To evaluate the incidence and appearance of renal infarctions after transrenal stent placement in an animal model.

METHODS

An aortic stent was placed via a femoral approach in 20 female Merino sheep. Ten animals had intentional coverage of one renal ostium with the bare struts, 1 sheep had both renal artery ostia covered, and the other 9 sheep had no stent impingement on the renal orifices. Animals were sacrificed after 3 to 12 months (mean 6) for gross pathological and histological evaluation. Infarction locations and patterns were evaluated and correlated to stent placement.

RESULTS

Of the 40 renal arteries, coverage was proven at autopsy in 12 cases; the remaining 28 arteries were free of any stent overlay. Overall, 14 (35%) renal infarctions were detected; 7 were found in the 12 arteries with a transrenal stent (58.3% incidence in covered renal arteries). By comparison, the other 7 infarctions were found in the 28 unaffected arteries (25% incidence in noncovered renal arteries; p = 0.04). All infarctions appeared to be well-defined punctate lesions.

CONCLUSIONS

A transrenal stent position in the abdominal aorta is related to increased renal infarctions in an animal model.

Reducing complications by better case selection: anatomic considerations

The feasibility of endovascular aortic aneurysm repair (EVAR) in any individual patient remains inherently dependent on the anatomy of the aorta and iliac arteries. There is a great deal of evidence in the literature that poor anatomic patient selection for EVAR will increase the risk of both procedure-related complications and compromised long-term outcomes. Inferior outcomes can include technical failures such as attachment-site endoleak, endograft migration, and ultimately aneurysm growth and rupture. Unfortunately, it is relatively rare to encounter a patient who possesses completely "ideal" anatomy for this technique. With the broadening spectrum of new devices applicable for the intraluminal treatment of abdominal aortic aneurysms, the vascular surgeon is challenged to be aware of individual selection criteria for the ever-widening variety of endoluminal grafts, in order to choose the optimal device for each patient's distinct anatomical situation. In patients who would otherwise be at high risk for traditional abdominal aortic aneurysm surgery based on medical comorbidities, the additional challenge for the practitioner who performs EVAR is to possess excellent judgment regarding just how far the anatomical "envelope" may be pushed without compromising patient outcomes.

Diameter of abdominal aortic aneurysm and outcome of endovascular aneurysm repair: does size matter? A report from EUROSTAR

OBJECTIVES

This study was undertaken to determine the effect of the preoperative diameter of abdominal aortic aneurysms on the midterm outcome after endovascular abdominal aneurysm repair (EVAR).

METHOD

The data for 4392 patients who had undergone EVAR were analyzed. Patients were enrolled over 6 years to June 2002 in the EUROSTAR database. Outcomes were compared between three groups defined by the preoperative diameter of the aneurysm: group A (n = 1962), 4.0 to 5.4 cm; group B (n = 1528), 5.5 to 6.4 cm; and group C (n = 902), 6.5 cm or larger. Patient characteristics, details of aortoiliac anatomy, operative procedures, old or current device generation, and postoperative complications in the three patient groups were compared. Outcome events included aneurysm-related death, unrelated death, conversion, and post-EVAR rupture of the aneurysm. Life table analysis and log-rank tests were used to compare outcome in the three study groups. Multivariate Cox models were used to determine whether baseline and follow-up variables were independently associated with adverse outcome events.

RESULTS

Patients in group C were significantly older than patients in groups A and B (73 years vs 70 and 72 years, respectively; P =.003 - P <.0001 for different group comparisons), and more frequently were at higher operative risk (American Society of Anesthesiologists classification >or=3; 63% vs 48% and 54%; P =.0002-P <.0001). Device-related (type I) endoleaks were more frequently observed at early postoperative arteriography in group C compared with groups A and B (9.9% vs 3.7% and 6.8%; P =.01-P <.0001). Postoperatively systemic complications were more frequently present in group C (17.4% vs 12.0% in group A and 12.6% in group B; P <.0001 and.001). The first-month mortality was approximately twice as high in group C compared with the other groups combined (4.1% vs 2.1%; P <.0001). Late rupture was most frequent in group C. Follow-up results at midterm were less favorable in groups C and B compared with group A (freedom from rupture, 90%, 98%, and 98% at 4 years in groups C, B, and A, respectively; P <.0001 for group C vs groups A and B). Aneurysm-related death was highest in group C (88% freedom at 4 years, compared with 95% in group B and 97% in A; P =.001 and P <.0001, respectively; group B vs A, P =.004). The annual rate of aneurysm-related death in group C was 1% in the first 3 years, but accelerated to 8.0% in the fourth year. Incidence of unrelated death also was higher in groups C and B than in group A (76% and 82% freedom at 4 years vs 87%; P <.0001 for both comparisons). Ratio of aneurysm-related to unrelated death was 23%, 21%, and 50% in groups A, B, and C, respectively. Cox models demonstrated that the correlation between large aneurysms (group C) and all assessed outcome events was independent and highly significant. Older generation devices had an independent association with aneurysm-related and unrelated deaths (P =.02 and P =.04, respectively). However, this correlation was less strong than large aneurysm diameter (P =.0001 and P =.0009, respectively).

CONCLUSIONS

The midterm outcome of large aneurysms after EVAR was associated with increased rates of aneurysm-related death, unrelated death, and rupture. Reports of EVAR should stratify their outcomes according to the diameter of the aneurysm. Large aneurysms need a more rigorous post-EVAR surveillance schedule than do smaller aneurysms. In small aneurysms EVAR was associated with excellent outcome. This finding may justify reappraisal of currently accepted management strategies.

Endovascular aneurysm repair with a bifurcated endovascular graft at a primary referral center: Influence of experience, age, gender, and aneurysm size on suitability

OBJECTIVE

The purpose of this study was to assess the suitability for endovascular repair of abdominal aortic aneurysm (EVAR) in an unselected patient population.

PATIENTS AND METHODS

Between February 1999 and May 2002 all consecutive patients with a nonemergent abdominal aortic aneurysm (AAA) were prospectively examined with contrast material-enhanced spiral computed tomography (CT). Those patients probably suitable for EVAR on the basis of CT findings underwent calibrated angiography. A panel of radiologists and vascular surgeons reviewed the clinical data and vascular anatomy, and decided on the appropriateness of EVAR with the bifurcated Zenith AAA endovascular graft.

RESULTS

One hundred seven patients were included. Fifty-six patients (52%) had one or more contraindications for EVAR. Unsuitability was most frequently (88%) related to the proximal neck. Inadequate neck length was the most common specific reason. Inadequate iliac anatomy was the reason for unsuitability in 59% of patients. The rate of unsuitability decreased from 61% during the first half of the study to 40% during the second half (P =.03) Unsuitability was equal between men and women. Age and maximum diameter did not differ between candidates and noncandidates.

CONCLUSION

Almost half (48%) of patients with an infrarenal AAA referred to a primary referral center are suitable for EVAR with the bifurcated Zenith AAA endovascular graft. Neck anatomy was the most frequent reason for rejection. Rate of suitability increased over time, probably as a result of increasing experience. Suitability was not influenced by gender, age, or aneurysm size.

Comparison of morphologic features of intact and ruptured aneurysms of infrarenal abdominal aorta

INTRODUCTION

Endovascular aneurysm repair (EVAR) has been suggested as a technique to improve outcome of ruptured abdominal aortic aneurysm (AAA). Whether this technique becomes an established treatment will depend, in part, on the anatomy of ruptured AAA.

METHODS

The anatomy of intact and ruptured AAA seen in a university department of vascular surgery over 5 years was reviewed. Aneurysm anatomy was assessed with spiral computed tomographic angiography. Suitability for EVAR was assessed from the dimensions of the proximal neck and common iliac arteries. Neck length less than 15 mm, neck width greater than 30 mm, and common iliac artery diameter greater than 22 mm were declared unsuitable for EVAR.

RESULTS

Three hundred sixty-three patients with intact AAA and 46 with ruptured AAA were identified. Larger intact aneurysms were significantly associated with longer renal artery-bifurcation distance and more complex proximal neck architecture. In this sample, patients with ruptured AAA were more likely to have larger aneurysms with shorter and narrower proximal necks. Significantly more intact aneurysms were morphologically suitable for endovascular repair compared with ruptured AAA (78% vs 43%; P <.001).

CONCLUSIONS

Ruptured AAA are less likely to be suitable for endovascular repair than are intact AAA, most probably because of larger diameter at presentation. Open repair will likely remain the treatment of choice in most patients with ruptured AAA, because of current morphologic constraints of endovascular repair.

Disparate outcome after endovascular treatment of small versus large abdominal aortic aneurysm

OBJECTIVES

The size of an abdominal aortic aneurysm is the most important parameter for determining whether repair is appropriate. This decision, however, must be considered in the context of long-term outcome of treatment, balancing risk for rupture with mortality from the initial procedure and all subsequent secondary procedures necessary when durability is not ideal. Information on the results of endovascular repair of small versus large aneurysms has not been available.

METHODS

Preoperative imaging studies and postoperative outcome were assessed in 700 patients who underwent endovascular repair of abdominal aortic aneurysm over 6 years at a single institution. Patients were divided into two groups: 416 patients (59.4%) with aneurysms smaller than 5.5 cm in diameter and 284 patients (40.6%) with aneurysms 5.5 cm or larger in diameter. Outcome variables were assessed with the Kaplan-Meier method and the log-rank test.

RESULTS

Patients with small and large aneurysms were comparable with regard to all baseline parameters assessed, with the single exception of a small increase in age (2.3 years) in patients with large aneurysms (P =.031). While there were no differences in rate of type II endoleaks, mid-term changes in sac diameter, or aneurysm rupture between the two groups, at 24 months patients with large aneurysms had more type I leaks (6.4% +/- 2.3% vs 1.4% +/- 0.6%; P =.011), device migration (13% +/- 4.0% vs 4.4% +/- 1.8%; P =.006), and conversion to open surgical repair (8.2% +/- 3.2% vs 1.4% +/- 1.1%; P =.031). Of greatest importance, at 24 months patient survival was diminished (71% +/- 4.6% vs 86% +/- 2.8%; P <.001) and risk for aneurysm-related death was increased (6.1% +/- 2.6% vs 1.5% +/- 1.0%; P =.011) in the group with large aneurysms.

CONCLUSIONS

Outcome after endovascular repair of abdominal aortic aneurysm depends on size; results appear inferior in patients with larger aneurysms. These differences attain importance when choosing between observation and repair, balancing risk for rupture against size-dependent outcome.

Nature, frequency, and predictors of secondary procedures after endovascular repair of abdominal aortic aneurysm

OBJECTIVES

Endovascular stent grafting offers a potentially less invasive option for treatment of abdominal aortic aneurysm. Clinical benefit has been demonstrated with respect to early parameters such as blood transfusion, return of gastrointestinal function, and length of hospital stay. Endovascular repair, however, has been criticized on the basis of inferior long-term outcome. Secondary procedures may be necessary to address durability issues such as migration, high-pressure endoleak, graft limb thrombosis, and degeneration of the stent-fabric structure itself, issues that may compromise the primary goal of aneurysm repair, protection from rupture.

METHODS

Between 1996 and 2002, 703 patients underwent endovascular treatment of infrarenal abdominal aortic aneurysm at The Cleveland Clinic Foundation. During this time, five devices were used: Ancure, AneuRx, Excluder, Talent, and Zenith. Outcome was assessed with physical examination, lower extremity arterial studies, plain abdominal radiography, and computed tomography at discharge, at 1, 6, and 12 months postoperatively, and annually thereafter. Secondary procedures were defined as any procedure, exclusive of diagnostic angiography, performed after stent graft implantation, directed at treatment of aneurysm-related events. Multivariable statistical techniques for censored data (Cox proportional hazards modeling) were used to determine baseline parameters associated with need for secondary procedures over follow-up, with calculation of hazards ratio (HR) and 95% confidence interval (CI).

RESULTS

Patient follow-up averaged 12.2 +/- 11.7 months. Patient survival was 90% +/- 1.4% at 1 year, 78% +/- 2.6% at 2 years, and 70% +/- 3.8% at 3 years. Aneurysm rupture occurred in 3 patients (0.4%), accounting for rupture risk of 1.4% over the first 2 years of follow-up (Kaplan-Meier method). Overall, 128 secondary procedures were required in 104 patients (15%), with a cumulative risk of 12% +/- 1.5% at 1 year, 24% +/- 2.8% at 2 years, and 35% +/- 4.4% at 3 years after stent graft implantation. Among the secondary procedures, new stent grafts and extensions were placed in 34 patients (27%), embolization of endoleak was performed in 33 patients (26%), and open surgical conversion was undertaken in 11 patients (9%). Periprocedural mortality of secondary procedures was 8% overall, but was 18% for patients undergoing open surgical conversion. Multivariable modeling identified the date the procedure was performed (HR, 1.53 per 3-month period of study; CI, 1.22-1.92; P <.001) and aneurysm size (HR, 1.35 per centimeter of minor axis; CI, 1.13-1.60; P <.001) as independent predictors of need for secondary procedures.

CONCLUSIONS

Current endovascular devices are associated with a relatively high rate of complications over mid-term follow-up, culminating in frequent need for secondary remedial procedures. With strict follow-up imaging compliance, however, risk for rupture and aneurysm-related death remain exceedingly low. Newer technology may achieve improved durability and a lower requirement for secondary procedures, while maintaining the minimally invasive nature of presently available devices.

The endovascular management of ruptured abdominal aortic aneurysms

Endovascular aneurysm repair (EVAR) is a controversial technique, which remains the subject of a number of prospective randomised trials. Although questions remain regarding its long-term durability objective evidence exists which demonstrates its reduced physiological impact compared with conventional open repair. If this technique could be used in patients with ruptured abdominal aortic aneurysm (AAA) it may reduce the high peri-operative mortality. A review of the literature identified a limited experience with EVAR of ruptured AAA. Only a small number of case series with selected patients exist. The majority of patients were haemodynamically stable. However, the selective use of aortic occlusion balloons allowed successful endovascular management in a small number of unstable cases. All investigators had access to an "off the shelf" endovascular stent-graft (EVG). Per-operative mortality ranged from 9 to 45% and may reflect increasing experience and patient selection. A number of patients who underwent successful EVAR were turned down for open repair. A number of important lessons have been learned from these studies but questions remain regarding patient suitability and staffing issues. If these difficulties can be surmounted then the technique may offer an alternative to open repair.

Aneurysm morphology as a predictor of endoleak following endovascular aortic aneurysm repair: do smaller aneurysm have better outcomes?

Since the Food and Drug Administrations' approval of endovascular devices for abdominal aortic aneurysm (AAA) repair, clinicians have been relaxing the strict inclusion criteria present during the clinical trials. Although the long-term natural history of endoleaks remains unclear, attachment site leaks (type I) are believed to represent an ongoing risk for future rupture. We reviewed our experience with endovascular AAA repair to elucidate factors that predispose toward the development of endoleaks and found that larger AAAs are significantly more likely to have a short proximal neck and severe proximal angulation. These factors likely contribute to the significantly increased rate of type I endoleaks that occurred after endovascular repair of large AAAs. Small AAAs (<5) had the lowest rate of endoleaks overall (8.3%) and of type I endoleaks in particular (0%). We conclude that AAA size and morphology can be used to predict which aneurysms will experience attachment site endoleaks in their course; AAAs from 4.5 to 5 cm in diameter may be particularly well suited for endovascular repair in this regard.

Endovascular abdominal aortic aneurysm repair in 144 patients: correlation of aneurysm size, proximal aortic neck length, and procedure-related complications

PURPOSE

During endovascular abdominal aortic aneurysm (AAA) repair, larger aneurysms often present formidable anatomic challenges to the insertion of the delivery catheter and graft deployment. The authors sought to evaluate whether large-diameter aneurysms and those with short proximal aortic necks might be associated with a higher frequency of insertion-related and short-term complications.

MATERIALS AND METHODS

From October 1999 to August 2000, 144 patients underwent elective endovascular graft placement for infrarenal AAA disease at the authors' institution. These patients were treated with use of the AneuRx bifurcated endoprosthesis. AAA size (maximum aneurysm diameter) and proximal aortic neck length were compared to estimated blood loss, operative time, accuracy of graft placement, presence of endoleak, intraoperative and postoperative complications (such as limb occlusion or vascular injury), length of hospital stay, and mortality. Statistical methods included correlation analysis and logistic regression.

RESULTS

There were 121 men and 23 women whose aneurysms ranged in size from 3 cm to 9.8 cm (mean, 5.6 cm; 95% CI, 5.4-5.8 cm). Endograft insertion was successful in all cases. There were three deaths within 30 days (2.1%) and seven deaths overall (4.9%). There were 43 intraoperative complications (29.9%) in 31 patients (21.5%), most of them minor. Patients with major intraoperative complications had significantly longer procedure times than those without complications (337 vs. 149 min; P <.0001). In the postoperative period (within 30 days), 31 complications (21.5%) occurred in 28 patients (19.4%), again most of them minor. AAA size was unrelated in any way to the rate of complications, but short proximal aortic neck length was associated with more serious intraoperative and postoperative complications (P =.0404 and P =.0230, respectively), and decreased 30-day and overall survival (P =.0240 and P =.0152, respectively).

CONCLUSIONS

Endovascular repair of large AAAs can be challenging; however, the size of the AAA does not influence the rate of complications. A short proximal aortic neck is the only significant risk factor for more serious complications.

Exclusion of accessory renal arteries during endovascular repair of abdominal aortic aneurysms

OBJECTIVE

Adequate proximal neck length is important for proper endovascular treatment of abdominal aortic aneurysms (AAAs). Placement of endografts in AAAs with relatively short proximal necks may require covering the origin of accessory renal arteries. Exclusion of these arteries carries the theoretical concern of regional renal ischemia associated with loss of parenchyma or worsening hypertension. We reviewed our experience with accessory renal exclusions during endovascular AAA repair to determine the frequency and severity of complications.

METHODS

Complete records were available for review on 311 of 325 consecutive patients treated with endovascular grafts for AAAs from February 6, 1996, to March 15, 2001. The presence of accessory renal arteries was ascertained from preoperative/intraoperative aortography or from computed tomographic scanning. Sizes of the accessories were measured by using the main renal arteries as a reference. Considerations for excluding the accessory renal arteries were based on the likelihood of successful proximal attachment to healthy aorta, an accessory vessel whose size does not exceed the diameter of the main renal artery, and the absence of renal disease.

RESULTS

The mean follow-up was 11.5 months. Fifty-two accessory renal arteries were documented in 37 patients (12%), ranging from 1 to > or =3 per patient. Of these, 26 accessory renal arteries were covered in 24 patients. Patients ranged in age from 57 to 85 years (mean, 74.1 years), with 20 men and 4 women. The Ancure device was used in 23 patients and the Excluder device in one. Of the accessories excluded, 22 originated above the aneurysm and 4 originated directly from the aneurysm itself. There were no perioperative mortalities. One patient died 5 months after surgery from an unrelated condition. There was one type I (distal) endoleak and no type II endoleaks. Five patients (21%) had segmental renal infarction associated with the side of accessory renal artery exclusion. Only one patient with segmental infarction had significant postoperative hypertension that resulted in changes in blood pressure medication. The blood pressure reverted to normal 3 months later. One patient with a stenotic left main renal artery required exclusion of the accessory renal artery for successful proximal attachment. Serum creatinine levels remained unchanged throughout follow-up in all but one patient, in whom progressive postoperative renal failure developed despite normal renal flow scan, presumably from intraoperative manipulation and contrast nephropathy.

CONCLUSION

Exclusion of accessory renal arteries to facilitate endovascular AAA repair appears to be well tolerated. Long-term sequelae seem infrequent and mild.

Endovascular Abdominal Aortic Aneurysm Repair in High-risk Patients: a Single Centre Experience

OBJECTIVES

to evaluate the role of endovascular repair (ER) of abdominal aortic aneurysm (AAA) repair in American Society for Anaesthesiology [ASA] class IV patients.

PATIENTS AND METHODS

between April 1997 and March 2000, 266 consecutive patients underwent ER for AAA. There were 26 patients (10%) with ASA grade IV. The remaining 240 patients, ASA grade between I and III (ASA<IV group), were compared with the ASA IV group. Mean follow-up was 11.6 months (range 1-32 months). Increase in AAA diameter after ER or persisting graft-related endoleak were defined as failure of AAA exclusion. Regression analysis was performed to test the effect of five confounding variables on failure of AAA exclusion and perioperative mortality.

RESULTS

patients in the ASA IV group were significantly older than patients in ASA <IV group (mean age: 74 years vs 70 years p=0.005). AAA were larger (mean diameter: 56 mm vs 50 mm p =0.002) and more extensive (class E of EUROSTAR classification: 27% vs 5.8% p =0.002). There were two perioperative deaths in the ASA IV group and one in the ASA<IV group (8% vs 0.4%; RR 19; 95% CI 1.8-202 p=0.01). Major perioperative morbidity occurred in 8% of patients in the ASA IV group and in 3.3% in the ASA<IV group (n.s.). There were no conversions to open repair in the ASA IV group while six were performed in the ASA<IV group (n.s.). Length of hospitalisation was significantly longer for patients in the ASA IV group: 7.8 days vs 3.2 days (p =0.001). Operative times and blood loss were similar. Failure of AAA exclusion occurred in two patients (8%) in the ASA IV group and in four patients (1.6%) in the ASA<IV group (n.s.). On life table analysis, survival rates at 26 months were 76% in the ASA IV group and 89% in the ASA<IV group (p =0.004). Five variables were examined by regression analysis and no independent predictors of failure of AAA exclusion and operative mortality were found.

CONCLUSIONS

ER in ASA IV patients is feasible and effective with acceptable actuarial survival rates. However, the endovascular procedure in these patients is associated with higher major systemic morbidity, mortality, and prolonged hospitalisation rates.

Predictive factors for early success of endovascular abdominal aortic aneurysm repair

To identify predictive factors for postoperative success and potential predictors for satisfactory outcome of endovascular grafting for abdominal aortic aneurysm (AAA), we collected data from our prospective database, which includes a series of consecutive patients undergoing endovascular repair at the Vascular Surgery Unit, Policlinico Monteluce, Perugia, Italy. From April 1997 to July 1998, 202 patients were referred to our Unit for elective AAA repair; 94 patients (47%) were selected for endografting. Placement of the graft using endovascular technique without conversion to open laparotomy, in addition to no mortality, major morbidity, or endoleak at 30-day follow-up, was defined as postoperative success. The influence of anatomical features on postoperative results was analyzed by univariate and multivariate analysis. Our experience shows that endoluminal repair of AAA is safe and effective in the short term and male patients with small aneurysms are optimal candidates for successful repair.

Should endovascular surgery lower the threshold for repair of abdominal aortic aneurysms?

PURPOSE

Because endovascular repair of abdominal aortic aneurysms (AAAs) is less invasive, some investigators have suggested that this increasingly popular technique should broaden the indications for elective AAA repair. The purpose of this study was to calculate quality-adjusted life expectancy rates after endovascular and open AAA repair and to estimate the optimal diameter for elective AAA repair in hypothetical cohorts of patients at average risk and at high risk.

METHODS

A Markov decision analysis model was used in this study. Assumptions were made on the basis of published reports and included the following: (1) the annual rupture rate is a continuous function of the AAA diameter (0% for <4 cm, 1% for 4.5 cm, 11% for 5.5 cm, and 26% for 6.5 cm); (2) the operative mortality rate is 1% for endovascular repair (excluding the risk of conversion to open repair) and 3.5% for open repair at age 70 years; and (3) immediate endovascular-to-open conversion risk is 5%, and late conversion rate is 1% per year. The main outcome measure in this study was the benefit of AAA repair in quality-adjusted life years (QALYs). The optimal threshold size (the AAA diameter at which elective repair maximizes benefit) was measured in centimeters.

RESULTS

The benefit of endovascular repair is consistently greater than that of open repair, but the additional benefit is small-0.1 to 0.4 QALYs. For men in average health with gradually enlarging AAAs with initial diameters of 4 cm, endovascular surgery reduces the optimal threshold diameter by very little: from 4.6 to 4.6 cm (no change) at age 60 years, from 4.8 to 4.7 cm at age 70 years, and from 5.1 to 4.9 cm at age 80 years. For older men in poor health, endovascular surgery reduces the optimal threshold diameter substantially (8.1 to 5.7 cm at age 80 years), but the benefit of repair in this population is small (0.2 QALYs).

CONCLUSION

For most patients, the indications for AAA repair are changed very little by the introduction of endovascular surgery. Only for older patients in poor health does endovascular surgery substantially lower the optimal threshold diameter for elective AAA repair.

Concurrent comparison of endoluminal repair vs. no treatment for small abdominal aortic aneurysms

Endoluminal repair of abdominal aortic aneurysms (AAA) requires the aneurysm to have a proximal neck of at least 1.5 cm between the renal arteries and the aneurysm. Therefore, there may be advantages in performing endoluminal repair in the early stages of aneurysm development. However, the results of endoluminal repair performed in patients with small aneurysms with favourable morphology are not known. The aim of this study was to determine whether a randomised trial of endoluminal repair vs. no treatment for small aneurysms would be justified by using a concurrent comparison of endoluminal repair vs. no treatment for AAA 5 cm or less in diameter in patients presenting to the same centre during a 4-year period.

METHODS

Data on 117 patients presenting with AAA 5 cm or less in diameter were entered into a registry. The decision to perform endoluminal repair vs. no treatment was based on the patient's preference following surgical consultation and investigation by computed tomography. This study reports the mortality, morbidity and survival of patients presenting between June 1992 and August 1996. During this time 43 patients had endoluminal repair and 67 patients had no treatment for small AAA. Seven patients were unfit for any intervention. Despite patient selection for different management in each group, close analysis revealed that the groups were similar with regard to co-morbidities and risk factors, as well as age, sex, and size of aneurysm. Follow-up was by progress CT scanning and ranged from 1 to 51 months (mean 18 months (NT) and 22 months (ER)).

RESULTS

Endoluminal repair failed in six of 43 patients (14%) and resulted in 11 (25%) local vascular complications. There were two perioperative deaths and one late death in this group. Twenty-one of 67 AAA (31%) patients in the no treatment group enlarged beyond 5 cm in diameter during the study period. There was one death from aneurysm rupture and one death from myocardial infarction in this group.

CONCLUSIONS

The patients in the endoluminal repair group have gained an asset in having their aneurysms repaired at a cost of early morbidity following operation. These results suggest that a randomised trial of endoluminal repair vs. no treatment will become justified in the subset of patients with small AAA 5 cm or less, if the incidence of complications can be reduced by further improvements in endoluminal technology.