Multicenter pivotal trial results of the Lifepath System for endovascular aortic aneurysm repair

Acute ischemia secondary to popliteal artery stent fracture and embolization

Femoropopliteal disease comprises more than one half of lesions in peripheral vascular disease. The treatment modalities for stenosis or occlusion of this anatomic region include femoropopliteal bypass and percutaneous transluminal angioplasty with or without stenting. Our patient developed acute leg ischemia 3 years after stenting, secondary to stent fracture, with distal embolization of stent fragments. Using mechanical thromboembolectomy and superficial femoral artery to below-the-knee popliteal in situ saphenous vein bypass, we were able to restore perfusion to the limb and retrieve fragments of the fractured stent.

A 52-year-old man with asymptomatic giant thoracic-abdominal aortic aneurysm

A 52-year-old man was admitted to our hospital for a "CT-diagnosed thoracic-abdominal aortic aneurysm." One week ago, the patient had repeated dry coughs and went to the local hospital for treatment. A chest radiograph revealed a huge mass in the left thoracic cavity. A further chest computerized tomography examination revealed a thoracic-abdominal aortic aneurysm and was transferred to our hospital for surgical treatment. The patient is almost healthy, with no fever, no severe chest and abdomen pain, no dyspnea, no dysphagia, or other clinical symptoms. Ten years ago, the patient underwent "ascending aorta and total aortic arch replacement surgery" in another cardiovascular hospital due to aortic dissection involving the ascending aorta and aortic arch (Debakey I). The patient's thoracic-abdominal aortic aneurysm is huge and has a high risk of rupture. Recently, the patient has undergone thoracic-abdominal aortic replacement surgery and is recovering well.

Surveillance Imaging following Endovascular Aneurysm Repair: State of the Art

Endovascular aneurysmal repair (EVAR) has become a prominent modality for the treatment of abdominal aortic aneurysm. Surveillance imaging is important for the detection of device-related complications, which include endoleak, structural abnormalities, and infection. Currently used modalities include ultrasound, X-ray, computed tomography, magnetic resonance imaging, and angiography. Understanding the advantages and drawbacks of each modality, as well available guidelines, can guide selection of the appropriate technique for individual patients. We review complications following EVAR and advances in surveillance imaging modalities.

Contemporary imaging methods for the follow-up after endovascular abdominal aneurysm repair: a review

Abdominal aortic aneurysm (AAA) is defined as a localized enlargement of the aortic cross-section where the diameter is greater than 3 cm or more than 50% larger than the diameter in a normal segment. The most important complication of AAA is rupture, which, if untreated, results in mortality rates of up to 90%. Conventional open surgical repair is associated with significant 30-day mortality. Endovascular aneurysm repair (EVAR) is a significantly less invasive procedure; it is related to a lower early mortality rate and a lower number of perioperative complications. Although EVAR is a minimally invasive technique, lifelong follow-up imaging is necessary due to possible late complications including endoleak, recurrent aneurysm formation, graft infection, migration, kinking and thrombosis. The total rate of complications after EVAR is estimated at approximately 30%, and the rate of complications that require intervention is 2–3%. Early detection and progression analysis of such situations is crucial for proper intervention.

Complications of endovascular aneurysm repair of the thoracic and abdominal aorta: evaluation and management

In recent decades, endovascular aneurysm repair or endovascular aortic repair (EVAR) has become an acceptable alternative to open surgery for the treatment of thoracic and abdominal aortic aneurysms and other aortic pathologies such as the acute aortic syndromes (e.g., penetrating aortic ulcer, intramural hematoma, dissection). Available data suggest that endovascular repair is associated with lower perioperative 30-day all-cause mortality as well as a significant reduction in perioperative morbidity when compared to open surgery. Additionally, EVAR leads to decreased blood loss, eliminates the need for cross-clamping the aorta and has shorter recovery periods than traditional surgery. It is currently the preferred mode of treatment of thoracic and abdominal aortic aneurysms in a subset of patients who meet certain anatomic criteria conducive to endovascular repair. The main disadvantage of EVAR procedures is the high rate of post-procedural complications that often require secondary re-intervention. As a result, most authorities recommend lifelong imaging surveillance following repair. Available surveillance modalities include conventional radiography, computed tomography, magnetic resonance angiography, ultrasonography, nuclear imaging and conventional angiography, with computed tomography currently considered to be the gold standard for surveillance by most experts. Following endovascular abdominal aortic aneurysm (AAA) repair, the rate of complications is estimated to range between 16% and 30%. The complication rate is higher following thoracic EVAR (TEVAR) and is estimated to be as high as 38%. Common complications include both those related to the endograft device and systemic complications. Device-related complications include endoleaks, endograft migration or collapse, kinking and/or stenosis of an endograft limb and graft infection. Post-procedural systemic complications include end-organ ischemia, cerebrovascular and cardiovascular events and post-implantation syndrome. Secondary re-interventions are required in approximately 19% to 24% of cases following endovascular abdominal and thoracic aortic aneurysm repair respectively. Typically, most secondary reinterventions involve the use of percutaneous techniques such as placement of cuff extension devices, additional endograft components or stents, enhancement of endograft fixation, treatment of certain endoleaks using various embolization techniques and embolic agents and thrombolysis of occluded endograft components. Less commonly, surgical conversion and/or open surgical modification are required. In this article, we provide an overview of the most common complications that may occur following endovascular repair of thoracic and AAAs. We also summarize the current surveillance recommendations for detecting and evaluating these complications and discuss various current secondary re-intervention approaches that may typically be employed for treatment.

Prospective cohort 20 years after endovascular treatment for abdominal aortic aneurysm

OBJECTIVE

To describe the factors associated with survival 20 years after endovascular treatment of an abdominal aortic aneurysm (AAA) in a single center.

METHODS

Prospective cohort of asymptomatic patients with an infrarenal aortic aneurysm treated with a bifurcated endovascular graft (Talent) between June 1997 and August 2008. Cox proportional hazard multivariable regression was used for analysis of independent risk factors for survival. Kaplan-Meier curves were done with the long-rank test. P < .05 was considered significant.

RESULTS

We followed 229 patients, 184 without an endoleak and 45 with an endoleak. Ages ranged between 52 and 89 years, and the mean diameter of the aneurysm was 59.51 ± 14.6 mm. Implantation of the endovascular graft was possible in 99% of the patients. The 30-day mortality rate was 3.4%. In the Cox regression, age <73 years (hazard ratio [HR], 0.42; 95% confidence interval [CI], 0.27-0.64), aneurysm size ≤55 mm (HR, 0.62; 95% CI, 0.40-0.95), male sex (HR, 0.17; 95% CI, 0.05-0.52), American Society of Anesthesiologists surgical risk category I and II vs III and IV (HR, 0.51; 95% CI, 0.34-0.75), and aneurysm size reduction ≤3 mm after treatment (HR, 2.23; 95% CI, 1.11-4.51) were significantly correlated with the survival of the patients followed in this long-term case series.

CONCLUSIONS

This 20-year prospective cohort included patients with an AAA treated with a bifurcated endovascular graft (Talent) at a university hospital in Brazil. This study supports that sex, age, aneurysm size, aneurysm size reduction, and American Society of Anesthesiologists surgical risk category are significantly correlated with patient survival after endovascular treatment of the AAA.

Limb graft occlusion following endovascular aortic repair: Incidence, causes, treatment and prevention in a study cohort

The present study investigated the incidence, causes, treatment and prevention of limb graft occlusion following endovascular aortic repair (EVAR). A total of 66 cases of abdominal aortic aneurysm receiving EVAR at our department from January 2005 to December 2013 were enrolled. After EVAR, patients received routine antiplatelet therapy of 75 mg PLAVIX for 6 months and then 100 mg Aspirin for another 6 months by oral administration. According to previous clinical experiences, antiplatelet therapy is able to effectively reduce the incidence of iliac occlusion after EVAR. A total of 61 bifurcated grafts and 5 aortauniilac grafts (127 limbs in total) were used. Physical examination, ankle-brachial-index and computer tomographic angiography were performed at 10 days, at 3, 6 and 12 months and annually thereafter. It was found that 7 limbs in 7 patients (10.6% of patients, 5.5% of limbs) were occluded between 20 days and 12 months (average, 7.8±5.3 months) after EVAR. Acute and severe ischemia was found in 2 cases, claudication was in found 3 cases, asthenia in both legs was found in 1 case and 1 case was asymptomatic. Femoral-femoral bypass, femoral-femoral bypass and stenting, aorto-iliac/femoral bypass, thrombectomy and conservative treatment were performed in 1 patient each and thrombectomy together with stenting was performed in 2 cases. Limb graft occlusion was not rare after EVAR. Treatment of this complication included surgery and endovascular therapy such as bypass, thrombectomy and thrombolysis. In conclusion, aggressive pre-emptive treatment including angioplasty and stenting prevented occlusion in certain cases.

Prevalence and risk factors of type II endoleaks after endovascular aneurysm repair: A meta-analysis

Objectives

This systematic review and meta-analysis aims to determine the current evidence on risk factors for type II endoleaks after endovascular aneurysm repair (EVAR).

Materials and methods

A systematic literature search was carried out for studies that evaluated the association of demographic, co-morbidity, and other patient-determined factors with the onset of type II endoleaks. Pooled prevalence of type II endoleaks after EVAR was updated.

Results

Among the 504 studies screened, 45 studies with a total of 36,588 participants were included in this review. The pooled prevalence of type II endoleaks after EVAR was 22% [95% confidence interval (CI), 19%–25%]. The main factors consistently associated with type II endoleaks included age [pooled odds ratio (OR), 0.37; 95% CI, 0.31–0.43; P<0.001], smoking (pooled OR, 0.71; 95% CI, 0.55–0.92; P<0.001), patent inferior mesenteric artery (pooled OR, 1.98; 95% CI, 1.06–3.71; P = 0.012), maximum aneurysm diameter (pooled OR, 0.23; 95% CI, 0.17–0.30; P<0.001), and number of patent lumbar arteries (pooled OR, 3.07; 95% CI, 2.81–3.33; P<0.001). Sex, diabetes, hypertension, anticoagulants, antiplatelet, hyperlipidemia, chronic renal insufficiency, types of graft material, and chronic obstructive pulmonary diseases (COPD) did not show any association with the onset of type II endoleaks.

Conclusions

Clinicians can use the identified risk factors to detect and manage patients at risk of developing type II endoleaks after EVAR. However, further studies are needed to analyze a number of potential risk factors.

Management of Abdominal Aortic Aneurysm: A Decade of Progress

Since the world was first introduced to the concept of endovascular aneurysm repair by Parodi's landmark procedures in 1990, stent-grafts have assumed a prominent role in the management of abdominal aortic aneurysm. Most modern systems are trackable, accurate, and secure. The resulting endovascular procedure is safe, durable, effective, and versatile. Perhaps the most significant increment in the applicability of the endovascular technique was achieved by the development of bifurcated stent-grafts, which dispensed with inadequate distal aortic implantation sites. Additional branches and fenestrations now permit endovascular repair in cases of thoracoabdominal, pararenal, juxtarenal, and bilateral iliac aneurysms. These advances in device performance have been accompanied by a rapid dissemination of necessary skills, leading to the development of a new superspecialty of vascular therapy, with elements of vascular surgery, interventional radiology, and interventional cardiology.

Surveillance Imaging Following Endovascular Aneurysm Repair

There is a significant risk of complication following endovascular abdominal repair (EVAR), including endoleak, graft translocation, thrombosis, and infection. Surveillance imaging is important for detecting EVAR complication. Surveillance modalities include conventional X-ray, computed tomography, magnetic resonance imaging, ultrasound, and conventional angiography, with inherent advantages and drawbacks to each modality. The authors present common complications following EVAR, and recent advances in the key modalities for surveillance.

Type II endoleak after endovascular aneurysm repair

Background

The aim was to assess the risk of rupture, and determine the benefits of intervention for the treatment of type II endoleak after endovascular abdominal aortic aneurysm repair (EVAR).

Methods

This systematic review was done according to PRISMA guidelines. Outcome data included incidence, spontaneous resolution, sac expansion, interventions, clinical success, and complications including conversion to open repair, and rupture.

Results

Thirty-two non-randomized retrospective studies were included, totalling 21 744 patients who underwent EVAR. There were 1515 type II endoleaks and 393 interventions. Type II endoleak was seen in 10·2 per cent of patients after EVAR; 35·4 per cent resolved spontaneously. Fourteen patients (0·9 per cent) with isolated type II endoleak had ruptured abdominal aortic aneurysm; six of these did not have known aneurysm sac expansion. Of 393 interventions for type II endoleak, 28·5 per cent were unsuccessful. Translumbar embolization had a higher clinical success rate than transarterial embolization (81 versus 62·5 per cent respectively; P = 0·024) and fewer recurrent endoleaks were reported (19 versus 35·8 per cent; P = 0·036). Transarterial embolization also had a higher rate of complications (9·2 per cent versus none; P = 0·043).

Conclusion

Aortic aneurysm rupture after EVAR secondary to an isolated type II endoleak is rare (less than 1 per cent), but over a third occur in the absence of sac expansion. Translumbar embolization had a higher success rate with a lower risk of complications.

Stent fabric fatigue of grafts supported by Z-stents versus ringed stents: An in vitro buckling test

Stent-grafts externally fitted with a Z-shaped stents were compared to devices fitted with ringed stents in an in vitro oscillating fatigue machine at 200 cycles per minute and a pressure of 360 mmHg for scheduled durations of up to 1 week. The devices fitted with Z-stents showed a considerably lower endurance limit to buckling compared to the controls. The contact between the apexes of adjacent Z-stents resulted in significant damage to the textile scaffolds and polyester fibers due to the sharp angle of the Z-stents. The ringed stents did not cause any fraying in the textile scaffolds.

Tratamento endovascular da oclusão de ramo ilíaco de endoprótese bifurcada de aorta abdominal: trombectomia rotativa e aspirativa seguida de angioplastia com stent primário

A oclusão de ramo ilíaco de endoprótese bifurcada de aorta surge como complicação decorrente da correção endovascular do aneurisma de aorta abdominal e várias abordagens terapêuticas têm sido empregadas para o tratamento dessa complicação em casos de isquemia de membro inferior. Apresentamos dois casos de tratamento totalmente percutâneo da oclusão de ramo ilíaco de endoprótese de aorta abdominal com dispositivo de trombectomia rotativa e aspirativa seguida de angioplastia com stent primário, sem complicações operatórias.

AAA stent-grafts: past problems and future prospects

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

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.

Long-term results of balloon-expandable LifePath endografts in abdominal aortic aneurysm: a single-center experience

OBJECTIVE

This retrospective single-center study analyzed long-term results after LifePath (Edwards Lifesciences LLC, Irvine, Calif) endoprosthesis implantation for abdominal aortic aneurysm (AAA), primarily focusing on the wire form fracture issue and consecutive endoleak rate.

METHODS

Between 1999 and 2004, all consecutive patients with LifePath AAA devices in our institution were included in the retrospective analysis. All patients had computed tomography angiography (CTA) imaging preoperatively and image postprocessing. The follow-up using CTA imaging specifically addressed material fatigue (wire form fractures) resulting in migrations and type I endoleaks.

RESULTS

During the 6-year study period, which included the 1-year withdrawal and redesign of the device, 51 patients were treated with LifePath AAA endografts. The 30-day mortality was 0%. The perioperative 30-day morbidity was 9.8%. One patient required a primary conversion due to misdeployment of the iliac limbs within the graft main body. The primary endoleak rate was 20.56% (type I, 2%; type II, 19.6%). During the mean follow-up of 40.7 months, 12 patients died, six were lost to follow-up, and 32 underwent subsequent CTA imaging. Eight patients (25%) demonstrated a proximal type I endoleak, seven (22%) had a type II endoleak, and three had a type III endoleak (9%). In nine patients (28.1%), wire form fractures could be detected at image postprocessing. Four patients required a secondary conversion due to endoleak and aneurysm growth (2 type I endoleaks and 2 type III endoleaks).

CONCLUSION

Wire form fracture is the major structural problem in the LifePath balloon-expandable endograft device, resulting in a significant endoleak rate. We must caution those patients with a LifePath device in-situ that careful follow-up must be performed due to material fatigue and they should consider secondary conversion.

Age-related trends in utilization and outcome of open and endovascular repair for abdominal aortic aneurysm in the United States, 2001-2006

OBJECTIVE

This study used a large national administrative in-hospital database to compare utilization and age-specific outcomes between open repair (OAR) and endovascular (EVAR) repair for the treatment of abdominal aortic aneurysm (AAA).

METHODS

Discharges with the principal International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) procedure codes for EVAR and OAR and principal diagnosis code of intact AAAs were selected from the 2001 to 2006 Nationwide Inpatient Sample (NIS). Weighted least-square regression was used to test the trend of utilization by age. Multiple linear and logistic regression analyses were used to assess the risk-adjusted outcomes.

RESULTS

Nationally, the estimated number of elective AAAs treated with EVAR increased from 11,171 in 2001 to 21,725 in 2006 (P = .003). The number of elective AAAs treated with OAR declined from 17,784 to 8451 during the same period (P < .001). By 2006, EVAR was more frequently used than OAR for patients of all ages. Compared with the younger age groups, patients aged >or=85 years had a significant increase in the total number of asymptomatic AAA repairs, driven almost entirely by an increase in the use of EVAR. Compared with open patients, EVAR patients had a significantly shorter length of hospitalization (adjusted mean, 2.99 days [95% confidence interval (CI), 2.97-3.01] vs 8.78 days [95% CI, 8.53-8.57]), less in-hospital mortality (odds ratio [OR], 0.23; 95% CI, 0.19-0.28), fewer in-hospital complications (OR, 0.27; 95% CI, 0.25-0.28), and a higher likelihood of being discharged to home (OR, 3.95; 95% CI, 3.62-4.31). The reduction of complications from the use of EVAR versus OAR was most dramatic for the oldest patients.

CONCLUSIONS

As short-term surgical outcomes are consistently improving for patients undergoing AAA repair, elective EVAR has replaced OAR as the more common method of repair in the United States. The introduction of this technology has been rapidly adopted, particularly for the oldest-old surgical patients, aged >or=85 years, who previously may not have been offered surgical intervention for asymptomatic AAA. Further investigation is necessary to examine whether this trend improves the long-term survival and quality of life for this elderly population.

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.

Percutaneous treatment of infrarenal aortic aneurysm with a polytetrafluoroethylene-covered nitinol stent-graft via a 10-F introducer sheath

Two patients with dissecting (n = 1) and saccular (n = 1) aneurysms of the infrarenal abdominal aorta with very narrow proximal and distal aortic necks underwent treatment with percutaneous implantation of self-expandable polytetrafluoroethylene (PTFE)-covered nitinol stent-grafts on an off-label basis. The stent-grafts had maximum diameters of 13.5 mm and were deployed via 10-F introducer sheaths. Complete coverage of both aneurysms was achieved without evidence of endoleaks. The only complication observed was a pseudoaneurysm of the femoral access site in one patient, which was treated conservatively. Based on the experience described in this report, an aortic aneurysm with a narrow aortic neck can be safely treated with a PTFE-covered nitinol stent-graft.

Preliminary Results of Anaconda™ Aortic Endografts: A Single Center Study

OBJECTIVE

To evaluate the peri-operative results of Anaconda endograft in the first 49 cases treated in a single centre.

METHODS

The study was carried out prospectively on cases of infrarenal abdominal aortic aneurysm (AAA) treated with Anaconda endograft. The characteristics of the proximal aortic neck and of the iliac access vessels were considered. The following operative results were assessed: the main body oversizing, the need to correct the positioning of the main body, the use of iliac extensions, the use of ballooning, the covering of patent hypogastric arteries, the presence of endoleaks and the need for conversion. Peri-operative (30 days) mortality and morbidity were also considered.

RESULTS

Of the 49 cases treated, 44 were males with a mean age of 73 years (range: 55-89 yrs; SD+/-7 yrs). The mean diameter of the AAA was 56 mm (range 45-91 mm; SD+/-11); 4 cases had common iliac aneurysms with a diameter >3 cm. The mean neck diameter and length were 23 mm (range 19-28 mm; SD+/-3) and 25 mm (range 15-50 mm; SD+/-10) respectively. An aortic neck angle between 40 degrees and 70 degrees was present in 10 cases (20%) (mean 58 degrees; SD+/-15 degrees), and 20 cases (41%) had iliac tortuosity with an angle greater than 60 degrees (mean 85 degrees; SD+/-25 degrees). There were no cases of conversion or intra-operative death. One (2%) peri-operative death occurred, for reasons not related to the endograft. There were two cases of iliac limb thrombosis. CT at one month showed 12 cases (25%) of type II endoleak. There were no cases of type I or type III endoleaks.

CONCLUSIONS

The preliminary data of this series demonstrates that the Anaconda endograft has good peri-operative results in the treatment of infrarenal AAAs with a neck length not less than 15 mm.

Development of endovascular stent-grafts

The very first experiences in the early 1990s with endovascular aortic stent-grafts were associated with significant numbers of complications including an inability to deploy the stent-graft, conversion to open surgery, and aneurysm rupture. By the mid-1990s, improved home-made and commercially available stent-grafts started to appear. These devices could be successfully deployed in the aorta, achieving aneurysm exclusion with low morbidity and mortality. However, follow-up results raised concerns about the longer-term durability. Gradually, too, these problems have been addressed such that, in the recent UK multi-centre randomized controlled trial of endovascular versus open aneurysm repair, aneurysm-related mortality was 3 per cent less in the endovascular group four years following surgery. Currently the indications for aortic stent-grafts are being expanded. It is now possible to maintain perfusion successfully in aortic side branches and to treat aneurysms that would have once been thought untreatable. This review paper reviews the main developments in endovascular stent-grafting and the major role played by medical engineering and technology.

Aortic Neck Dilatation and Endograft Migration Are Correlated With Self-Expanding Endografts

PURPOSE

To compare self-expanding and balloon-expandable stent-grafts in terms of aortic neck dilatation and endograft migration.

METHOD

Two-hundred and forty-two patients (178 men; mean age 68 years, range 56-91) underwent elective endovascular repair of abdominal aortic aneurysm. Two-hundred self-expanding (115 Excluder, 48 Endologix, 23 Vanguard, 10 Anaconda, and 4 Talent) and 42 balloon-expandable (Lifepath) endografts were used. All patients underwent contrast-enhanced computed tomography (CT) prior to the intervention, at 1, 3, and 6 months after the procedure, and annually thereafter. Comparison was made between the first and the last follow-up CT scans.

RESULTS

Fifty-five (27.5%) of the 200 patients treated with self-expanding endografts had aortic neck dilatation compared to only 3 (7.1%) of the 42 patients treated with balloon-expandable endografts (p = 0.023). Forty-nine (24.5%) patients in the self-expanding group versus only 3 (7.1%) patients of the balloon-expandable group presented with endograft migration (p = 0.034); all had dilated necks. The difference between the means of neck dilatation for the Lifepath balloon-expandable stent-graft and the Excluder self-expanding endoprosthesis was statistically significant (p = 0.011, 95% CI 0.07 to 0.91).

CONCLUSION

Aortic neck dilatation following endovascular AAA repair appears to be correlated with self-expanding endografts, which may contribute to a higher incidence of graft migration compared to that occurring with balloon-expandable endografts.

Renal transplantation after endovascular repair of abdominal aortic aneurysm

An increasing number of abdominal aortic aneurysms (AAA) occur in renal failure patients because of strong association between atherosclerosis and chronic kidney disease. Endovascular aneurysm repair (EVAR) has proven to be an effective modality to treat AAA, particularly in patients with renal disease, because of its several advantages over the standard open procedure, including lower morbidity, shorter operative time, and shorter hospital stay. A Medline search showed a single publication on renal transplantation (RT) following EVAR of AAA. In this context, we report our case of successful RT in a patient who had undergone EVAR 2 years prior for a 5.7-cm AAA. No stent-related complications, such as graft occlusion, dislodgement, dissection, or endoleak, were observed in the perioperative period. The transplanted kidney had primary function leading to a stable serum creatinine of 115 micromol/L at 6 months. Although the long-term outcome of RT after endovascular repair of AAA remains unknown, currently available evidence shows favorable outcomes of EVAR in the normal population, in patients with renal diseases, and in RT recipients; hence, RT should not be denied to renal failure patients who have undergone EVAR in the past.

Detecting Endoleaks in Aortic Endografts Using Contrast-Enhanced Sonography

OBJECTIVE

We performed this pilot study to investigate the utility of contrast-enhanced sonography for the detection of endoleaks in patients with abdominal aortic endografts.

CONCLUSION

Contrast-enhanced sonography evaluation of abdominal aortic endografts is a technically feasible alternative to our current practice standard.

A Shorter Skin Incision Technique for the Repair of Infrarenal Abdominal Aortic Aneurysms

PURPOSE

We evaluated the effectiveness of a shorter skin incision technique for the treatment of infrarenal abdominal aortic aneurysms (AAA). The aim of the present study was to evaluate whether or not the difference in the length of the skin incision contributed to an early recovery after the operation.

METHODS

Between October 2001 and December 2004, we performed 105 elective repairs for AAA. The patients were divided into three groups according to the length of the skin incision as follows: group A, less than 15 cm, group B, from 15 cm to less than 20 cm, and group C, 20 cm or more.

RESULTS

There was no significant difference in the intraoperative course among the three groups. The duration of paralytic ileus was shorter in group A than in group C (2.0 +/- 0.9 days versus 3.2 +/- 2.3 days; P = 0.0428). Although the periods before removal of nasogastric suction and before starting a solid diet were slightly shorter in group A than in groups B and C, there were no statistically significant differences.

CONCLUSION

We define minimally invasive vascular surgery as surgery performed with a small abdominal skin incision that does not expose the intestine to air while providing a good operative field that does not place any undue stress on the surgeon.

In vivo MR angiographic quantification of axial and twisting deformations of the superficial femoral artery resulting from maximum hip and knee flexion

PURPOSE

The goal of this study was to quantify in vivo deformations of the superficial femoral artery (SFA) during maximum knee and hip flexion with use of magnetic resonance (MR) angiography to improve description of the complex, dynamic SFA environment.

MATERIALS AND METHODS

Contrast medium-enhanced MR angiography was performed on the leg vasculature of eight healthy adults in the supine and fetal positions. The SFA was defined as the centerline path of the iliofemoral segment from the profunda femoris to the descending genicular artery. Deformations that resulted from flexion from the supine position to the fetal position were quantified with the SFA path and its branches.

RESULTS

Fourteen SFAs shortened from the supine position to fetal position, whereas two lengthened. Six of eight left SFAs twisted counterclockwise, and seven of eight right SFAs twisted clockwise. Straightness percentages for supine and fetal SFAs were 99.1%+/-0.4% and 98.7%+/-0.6%, respectively. From the supine position to the fetal position, the SFA shortened 13%+/-11% (P<.001) and twisted 60 degrees+/-34 degrees (P<.001). SFA arc length and percent shortening were strongly correlated (r>.8) between left and right limbs; however, no significant correlation existed for SFA twist angle.

CONCLUSIONS

Complex and varying vascular and muscular anatomy among study participants made SFA lengths and deformations from the supine position to the fetal position unpredictable a priori; however, there were strong symmetries between left and right SFAs in terms of arc length, length change, and direction of twist. The data show that, from the supine position to the fetal position, the SFA tended to shorten and twist substantially, suggesting these as possible fracture mechanisms and also providing important parameters for stent design.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Type II Endoleak after Endoaortic Graft Implantation: Diagnosis with Helical CT Arteriography

PURPOSE

To retrospectively assess endoleak shapes and locations within aneurysms to differentiate type II from type I and type III endoleaks.

MATERIALS AND METHODS

The institutional review board granted an exemption for this HIPAA-compliant study; patient informed consent was not required. A retrospective review of arterial phase helical computed tomographic (CT) studies and medical records was performed for 39 patients (29 men, 10 women; age range, 60-89 years; mean, 78.5 years) who had an endoleak after endoaortic graft implantation for treatment of abdominal aortic aneurysm and who subsequently underwent angiography (n = 25), surgery (n = 8), or long-term follow-up (n = 6) to classify their endoleak into a specific type. At CT, endoleak shape (tubular or nontubular) and location (central or peripheral) were recorded. An endoleak was classified as type II if it contained a peripheral tubular component (PTC) near the aortic wall, with or without an identifiable feeding vessel. Endoleaks without these features were classified as type I or III. The Fisher exact test was used to assess associations between CT findings and endoleak type.

RESULTS

There were 22 type II and 17 type I or III endoleaks. CT enabled correct identification of 22 (100%) of 22 type II endoleaks, all of which contained a PTC. Of 17 type I or III endoleaks, only two (12%) contained a PTC and were misclassified as type II endoleaks; the remaining 15 (88%) were correctly classified. Overall, CT enabled correct identification of endoleaks as type II or type I or III in 37 (95%) of 39 patients. PTCs were significantly more common (P < .001) in type II than in type I or III endoleaks, with a sensitivity, specificity, accuracy, negative predictive value, and positive predictive value of 100%, 88.2%, 94.9%, 100%, and 91.7%, respectively.

CONCLUSION

A PTC is a statistically significant predictor of type II endoleak in most patients.

Aorfix stent graft for abdominal aortic aneurysms reduces the risk of proximal type 1 endoleak in angulated necks: bench-test study

Neck angulation (NA) is an important risk factor for type 1 proximal endoleaks following stenting of abdominal aortic aneurysms. The Aorfix (Lombard Medical, Oxon, UK) is a new flexible stent graft designed to overcome this issue. The aim of this study was to compare the endoleak flow rate (EFR) in relation to NA between the Aorfix and other manufactured stent grafts. A flow model with silicone proximal and distal necks was used. EFRs corresponding to 10 neck angles between 0 and 70 degrees were measured. Eight stent grafts were tested: Aorfix, Ancure (Guidant, Indianapolis, IN), Powerlink (Endologix, Irvine, CA), AneuRx (Medtronic, Sunnyvale, CA), Excluder (W.L. Gore & Associates, Flagstaff, AZ), Zenith and Zenith-Flex (Cook Inc., Bloomington, IN), and Lifepath (Edwards Lifesciences, Irvine, CA). For all stent grafts except the Aorfix, the EFR was greater than at baseline for NA >or= 30 degrees (p < .01). The EFR at NA >or= 30 degrees was lower with the Aorfix compared with the other stent grafts (p < .01). NA had no influence on the EFR with the Aorfix. The Aorfix may decrease the incidence of proximal type 1 endoleak in patients with a severely angulated aortic neck.

Clinical Significance of Type II Endoleak after Endovascular Repair of Abdominal Aortic Aneurysm

Type II endoleaks after endovascular repair of abdominal aortic aneurysm (EVAR) are a result of retrograde flow from arterial branches (e.g., lumbar and inferior mesenteric) refilling the aneurysm sac, which has been excluded by the stent graft. Controversy continues with regard to the clinical significance and treatment of type II endoleaks. To develop recommendations for management, we analyzed outcome data from 10 EVAR trials completed over the last 5 years involving a total of 2,617 cases. The incidence of type II endoleak at discharge or 30 days was 6-17%, at 6 months 4.5-8%, and at 1 year 1-5%. Successful resolution of endoleak following secondary interventions was observed in 11-100% of cases. There were 10 conversions to open repair and no ruptures related to type II endoleak. In patients observed for 12 months with computed tomography and/or ultrasound, approximately one-half of type II endoleaks disappeared spontaneously. In the absence of a type I endoleak, our analysis of the current literature suggests that intervention for type II endoleak should be undertaken for abdominal aortic aneurysm sac enlargement occurring after 6 months, persistence for >12 months without abdominal aortic aneurysm sac enlargement, or an aneurysm sac pressure >20% of systolic blood pressure; translumbar aneurysm sac thrombosis and intra-arterial feeding vessel occlusion appear to be prudent management options.

Secondary interventions after endovascular abdominal aortic aneurysm repair

BACKGROUND

One adverse outcome of endovascular abdominal aortic aneurysm (AAA) repair (EVAR) is a significantly increased incidence of secondary interventions (SIs) required compared with traditional open aortic repair. We present a consecutive series of EVARs using a single endograft to identify the incidence and types of SIs performed.

METHODS

From February 1, 2000, to January 31, 2005, we repaired 136 AAAs with the Zenith (Cook, Bloomington, Indiana) endograft. All patients met the same strict anatomic inclusion and exclusion criteria. Follow-up lasted from 1.5 to 61 months (median 36). The indications for SI group A were procedural and technical errors, for group B were aortic morphology, and for group C were device failures.

RESULTS

Twenty-one SIs were required in 17 of 136 patients (12.5%). Three patients required multiple interventions. Nine patients were in group A, four were in group B, and six were in group C. All but 4 patients required SIs for late (>30 days) complications.

CONCLUSIONS

Although it is a viable alternative to open aortic repair, EVAR is associated with a significantly higher rate of SIs. To maintain the efficacy of EVAR, patients must be followed-up in a vigilant graft surveillance protocol for life.