Stent-graft migration after endovascular repair of abdominal aortic aneurysm

Endograft platform does not influence aortic neck dilatation after infrarenal endovascular aneurysm repair with primary endostapling

OBJECTIVES

Aortic endografts used for endovascular aneurysm repair (EVAR) are based on varying skeletal platforms such as stainless steel or nitinol stents, using radial force applied to seal at the aneurysm neck, and varying proximal fixation methods, applying either suprarenal or infrarenal fixation. This study assesses whether varying skeleton/fixation platforms affect neck-related outcomes after primary endostapling with Heli-FX EndoAnchors at EVAR.

METHODS

Retrospective analysis of a prospective database of infrarenal EVAR undertaken at a single centre. Chimney-EVAR, secondary cases were excluded. Primary outcomes analysed included neck diameter evolution from pre-EVAR to latest imaging follow-up, including a comparison of stent platforms to see if there was any outcome difference between those using stainless steel or nitinol, as also freedom from type I endoleakage and migration. Secondary outcomes assessed included average number of EndoAnchors, and sac size patterns before and after EVAR.

RESULTS

A total of 101 patients underwent endostapled infrarenal EVAR between September 2013 and March 2020. After exclusion of ineligible patients, 84 patients (76 male, 8 female, age 73.7 ± 7.8 years) were available for analysis. 57/27 endografts used suprarenal/infrarenal fixation, whilst 16/68 devices were based on stainless steel/nitinol platforms, respectively. Mean oversizing was higher for stainless steel/suprarenal fixation endografts (p = 0.02). A total of 582 EndoAnchors were deployed, averaging 7 ± 2 per patient. Median neck diameter was 25 mm (IQR 22-31) with 22 necks having non-parallel morphology (conical, tapered or bubble). Median follow-up period was 28.5 (IQR 12-43) months. Neck evolution studies suggested aortic neck dilatation of 5 ± 4 mm (p <0.001, paired T-test), independent of platforms employed (p = NS, ANOVA). There was no endograft migration; one immediate post-EVAR endoleak settled by eight weeks. There was a mean 5.7 ± 8.2 mm sac size reduction (p < 0.001, paired T-test).

CONCLUSION

Aortic neck dilatation occurs after EVAR with primary endostapling, but the process may be independent of stainless steel/nitinol platforms, possibly due to the attenuating effect of EndoAnchors. Adjunct aneurysm neck fixation by primary endostapling prevents migration regardless of whether suprarenal/infrarenal fixation is the primary fixative method. Device platform choice therefore may be left to the operator discretion if primary endostapling is applied at EVAR. Freedom from complications such as migration and endoleakage in the intermediate term suggests a higher level of 'tolerance' to aortic neck dilatation with primary endostapling. We would therefore suggest routine usage of EndoAnchors at EVAR when not otherwise contraindicated.

Device-Specific Resistance to in Vivo Displacement of Stent-Grafts Implanted with Maximum Iliac Fixation

Purpose:

To compare the in vivo device-specific downward displacement force of various externally supported endografts implanted with maximum iliac fixation.

Methods:

Twenty female sheep had aneurysms created with a graft patch in the infrarenal aorta. In 12 animals, a fully supported modular bifurcated stent-graft [AneuRx (n=4), Talent (n=4), or Zenith (n=4)] was deployed; in the other 8, a bifurcated aortic graft was surgically anastomosed to the infrarenal aorta. All grafts were displaced in vivo by applying downward traction to a guidewire brought out both femoral arteries. The peak force to cause initial stent-graft migration or disruption of the sutured anastomosis was recorded and compared.

Results:

There was no difference in animal size, aortic neck diameter or length, aneurysm size, or iliac artery diameter for animals receiving the AneuRx, Talent, or Zenith stent-grafts and those undergoing surgical repair. The mean length of iliac fixation was 31.0±0.3 mm, 30.8±0.5 mm, and 31.3±0.6 mm for the AneuRx, Talent, and Zenith devices, respectively (p=NS). Peak force to initiate migration was 30.2=5.5 N (range 25–38) for the AneuRx, 44.8±5.5 N (range 40–53) for the Talent, 46.7±5.4 N (range 38–55) for the Zenith, and 40.6±7.5 N (range 31–50) for the surgical anastomosis (p=0.01). There was no difference detected in the peak force to initiate migration between the suprarenally affixed Talent and Zenith stent-grafts and the surgical anastomosis (p=0.55).

Conclusion:

Devices with a suprarenal component require significantly greater force to cause downward displacement compared to infrarenal devices. The force required to displace a suprarenal device with maximal iliac fixation was equivalent to the force required to disrupt a surgical anastomosis.

CT angiography in the diagnosis of cardiovascular disease: a transformation in cardiovascular CT practice

Computed tomography (CT) angiography represents the most important technical development in CT imaging and it has challenged invasive angiography in the diagnostic evaluation of cardiovascular abnormalities. Over the last decades, technological evolution in CT imaging has enabled CT angiography to become a first-line imaging modality in the diagnosis of cardiovascular disease. This review provides an overview of the diagnostic applications of CT angiography (CTA) in cardiovascular disease, with a focus on selected clinical challenges in some common cardiovascular abnormalities, which include abdominal aortic aneurysm (AAA), aortic dissection, pulmonary embolism (PE) and coronary artery disease. An evidence-based review is conducted to demonstrate how CT angiography has changed our approach in the diagnosis and management of cardiovascular disease. Radiation dose reduction strategies are also discussed to show how CT angiography can be performed in a low-dose protocol in the current clinical practice.

Early in Vivo Analysis of an Endovascular Stapler During Endovascular Aneurysm Repair

The objective of this article is to describe the use and technique of a novel endostapling device used in an in vivo animal model. Six ovine underwent implantation of a Dacron endograft into the thoracic aorta followed by placement of endoclips proximally and distally. The animals were survived 35 days to evaluate the performance and safety of the endoclip in an animal model prior to clinical trials. The mean time for securing both the proximal and the distal anastomosis was 22 minutes (range 17–31 minutes). All staples were deployed, without the need for repositioning, on the first attempt. There were no complications related to the implant procedure or indwelling clips. Additionally, no endograft migration occurred. At the time of expiant, staples were evaluated for depth of penetration and accuracy of placement. The staples had fully penetrated the endograft and vessel wall through the adventitia in 89% (64 of 72) of clips deployed. The staples were placed accurately, within 10 mm of the endograft proximal and distal attachments in 94% (68 of 72) of the clips deployed. Furthermore, endothelialization of the staples was present without surrounding thrombus. Implant sites were scored as normal without surrounding tissue damage by an independent pathologist. The endoclip performed well in creating proximal and distal fixation of the endograft. There were no adverse outcomes related to the endostaple. Future clinical trials should be undertaken to assess its clinical utility during endovascular aneurysm repair.

No Difference in Medium-Term Outcome Between Zenith and Talent Stent-Grafts in Endovascular Aneurysm Repair

Background Many devices are available for endovascular aneurysm repair (EVAR). Our aim was to analyze morphological effects of the Zenith and Talent systems.

Methods Patients included underwent EVAR from June 1999 to June 2005 using a Zenith or Talent stent-graft, with computed tomography follow-up. Aortic dimensions over time and clinical outcome were analyzed.

Results Twenty-nine patients with Zenith stent-grafts and 33 with Talent devices were included. Mean preoperative age was similar (75.5 ± 6.0 years vs 74.2 ± 6.7 years; P = .29). Preoperative neck length was longer in the Zenith group (29.9 ± 15.2 mm vs 25.5 ± 10.8 mm; P = .10), and stent-graft oversizing was greater in the Talent patients (20.2% ± 7.9% vs 23.0% ± 11.3%). There was proximal aortic dilatation and aneurysm sac shrinkage in each group. Complication rates were comparable, with 83% of both groups free from 10-mm migration.

Conclusion Although device designs differ, there is no difference in clinical outcome between Zenith and Talent stent-grafts. Migration rates were not influenced by suprarenal fixation.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

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

Endovascular treatment of abdominal aortic aneurysms

BACKGROUND

Endovascular treatment of abdominal aortic aneurysms is a rapidly evolving technique that has gained broad acceptance in the treatment of patients with abdominal aortic aneurysms.

METHODS

A review of the English literature was done to determine the short- and long-term outcomes of endovascular repair of abdominal aortic aneurysms. Reports of complications such as endoleak, graft migration, graft limb occlusion, aneurysm rupture, and aneurysm enlargement were evaluated.

RESULTS

Short-term results of endovascular repair of abdominal aortic aneurysms are excellent. The necessity for open conversions is less than 5%. The cumulative risk of aneurysm rupture is approximately 1% per year. The coverall incidence of graft limb occlusion was 2.8% in the follow-up period. The cumulative risk for a secondary procedure was 12% at 1 year, 24% at 2 years, and 35% at 3 years. Moderate and severe neck angulation was associated with an increased incidence of adverse events in the follow-up period. Endografts have the potential to become infected and develop aortoduodenal fistula. The treatment of ruptured aneurysms with endovascular grafts has been successful and a technique that is increasingly used.

CONCLUSION

Endovascular treatment of abdominal aortic aneurysm is an effective technique with excellent short-term results. The long-term results remain to be determined. Ongoing surveillance is necessary to avoid late complications of aneurysm rupture.

Endovascular grafting of complex aortic aneurysms with a modular side branch stent-graft system in a porcine model

OBJECTIVES

To evaluate and refine a stent-graft system with side branches for treatment of aneurysms with essential branch arteries.

METHODS

In a porcine model (n=4) supra- and juxta-renal aortic aneurysms were created by suturing an artificial patch onto an anterior aortotomy. Angiography was performed to determine the exact location of the renal arteries. Accordingly, fenestrations were created in an appropriately sized aortic stent-graft. Initial deployment of the aortic graft is partial, whereby the top stent is secured in a cap and distal stents are being restrained, thus ensuring longitudinal and rotational manoeuvrability during alignment of the branch arteries. Separate branch grafts with silicone flanges for connection with the main stent-graft are subsequently placed in the renal arteries followed by full deployment of the main stent-graft. Outcome was evaluated by postoperative angiography and autopsy results and by measuring operating time, blood loss and use of contrast agent.

RESULTS

Branched grafts were placed successfully in all trials. The median endovascular procedure time was 126 min (90-160), with 575 ml (400-800) blood loss and 65 ml (50-80) contrast agent use. Angiographically, all aneurysms were excluded without signs of endoleak and all renal arteries were patent. At autopsy, the main stent-graft and all side branches were adequately placed with intact connections between main stent-graft and branch grafts.

CONCLUSIONS

In this model, endovascular repair of complex aneurysms using a modular branch graft system is feasible in a reliable, predictable and timely fashion.

Perioperative outcomes after open and endovascular repair of intact abdominal aortic aneurysms in the united states during 2001

OBJECTIVE

Small patient numbers, mixed data from clinical trials, and longitudinal series representing institutional learning curves have characterized previous studies of early outcomes after endovascular abdominal aortic aneurysm (AAA) repair. We compared the perioperative outcomes of endovascular and open surgical AAA repair in an unselected sample of patients in a single calendar year using a national administrative database.

METHODS

The 2001 National Inpatient Sample database was retrospectively reviewed. This database represents 20% of all-payer stratified sample of non-federal US hospitals. Patients older than 49 years were identified by primary diagnostic codes (International Classification of Disease, ninth revision [ICD-9], 441.4, intact, nonruptured AAA) and procedure codes (ICD-9 38.44 for open, 39.71 for endovascular repair). Patient demographic data (age, sex), comorbid conditions (ICD-9 coded), inpatient complications (ICD-9 coded), length of stay, final discharge disposition (home vs institution vs death), and hospital charges were examined with univariate and multivariate analyses.

RESULTS

In calendar year 2001, 7172 patients underwent either open (64%) or endovascular (36%) repair of intact, nonruptured AAAs. Despite comparable rates of preoperative comorbid conditions and a greater proportion of octogenarians (23% vs 16%%; P =.0001), morbidity (18% vs 29%; P =.0001) and mortality (1.3% vs 3.8%; P =.0001) were significantly lower for endovascular repair than for open repair. The median length of stay (2 vs 7 days; P =.0001) and the rate of discharge to an institutional facility versus home (6% vs 14%; P =.0001) were also much lower in the endovascular group than in the open repair group. At multivariate analysis, open AAA repair and age older than 80 years were strong independent predictors (P =.0001 for all) for death (open repair: odds ratio [OR], 3.3; 95% confidence interval [CI], 2.3-4.9; age: OR, 14.2; 95% CI, 3.5-58.1), complications (open repair: OR, 1.9; 95% CI, 1.7-2.1; age: OR, 1.9; 95% CI, 1.5-2.5), and not being discharged to home (open repair: OR, 3.4; 95% CI, 2.9-4.1; age: OR, 12.0; 95% CI, 7.0-20.4). Mean hospital charges were significantly greater (difference, $3337; P =.0009) for endovascular repair than for open repair. Extrapolated to the total number of endovascular AAA repairs performed during the single 2001 calendar year, this resulted in a staggering $50.3 million in additional hospital charges.

CONCLUSIONS

Endovascular repair of intact AAAs results in a significantly lower number of complications and deaths, shorter hospital stay, and improved likelihood of discharge to home, even in older patients, when compared with open surgical repair. These impressive gains in clinical outcome, however, are achieved at similarly impressive increases in health care costs.

Endovascular management of juxtarenal aneurysms with fenestrated endovascular grafting

PURPOSE

To evaluate the technical feasibility and short-term results of juxtarenal aneurysm repair with an endovascular graft that incorporated the visceral aortic segment with graft material.

METHODS

Patients were studied prospectively after the implantation of an endovascular device with graft material extending proximal to the renal arteries, variably incorporating the superior mesenteric and celiac arteries. All patients were deemed to be high risk with respect to open surgical repair and had compromised proximal neck anatomy. Proximal neck lengths were <or=10 mm, or <or=15 mm with a challenging morphology (funnel shape or extensive thrombus). Fenestrations within the graft material were customized to accommodate visceral and renal vessels on the basis of computerized tomography (CT), angiography, or intravascular ultrasound data. Selected visceral ostia were protected with balloon-expandable stents after partial endograft deployment. All patients were evaluated with CT and kidney, ureters, and bladder x-ray at discharge and at 1, 6, and 12 months. Visceral duplex scan studies were performed at 1, 6, and 12 months.

RESULTS

A total of 22 patients were enrolled in the study. Sixteen patients had short proximal necks (3-10 mm), and six had compromised necks of 10 to 15 mm in length. Endograft design included bifurcated (20) and tube (2) systems. All prostheses were implanted successfully without the acute loss of any visceral arteries. A total of 58 visceral vessels were incorporated (mean, 2.6 per patient) and most commonly included both renal arteries and the superior mesenteric artery. The mean follow-up was 6 months. There were no deaths within 30 days and no aneurysm-related deaths during the follow-up period. Two early (<30 days) and two late secondary interventions were performed, inclusive of two visceral artery stenoses detected with duplex scanning. The 30-day endoleak rate was 4.5%. The aneurysm sac decreased greater than 5 mm in 53 % of patients at 6 months and three of four patients at 12 months. Three patients developed renal insufficiency, only one of which required temporary hemodialysis.

CONCLUSIONS

The placement of an endovascular prosthesis with graft material that incorporates the visceral arteries is technically feasible. The occurrence of endoleaks appears to be relatively low. The increased sealing and fixation zones in this patient population should limit the late development of proximal endoleak or migration; however, this situation will require more patients and extended follow-up.

Factors Affecting the Displacement Force Exerted on a Stent Graft after AAA Repair—An In vitro Study

OBJECTIVES

To investigate the distraction forces affecting grafts used to treat abdominal aortic aneurysms in an in vitro model.

METHOD

Using a standard cardiac pump and a rigid plastic circulation system, distraction forces were measured with a gramometer attached to a PTFE graft while the pressure inside a rigid aortic sac was varied.

RESULTS

If the pressure in the 'aneurysm sac' is maintained at the same level as the systemic pressure, the displacement force is zero. The displacement force is affected adversely by the level of systemic pressure, as this rises the displacement forces rise in an almost linear fashion.

CONCLUSIONS

These observations may have important consequences for stent graft design and use in vivo pressurisation of a sealed sac may therefore not necessarily be an adverse event. Systemic hypertension is obviously important and its control may be necessary to prevent graft migration.