Aortic Side Branches Research Articles

Inferior Mesenteric Arterial Type II Endoleaks after Endovascular Repair of Abdominal Aortic Aneurysm: Are They Predictable?

To evaluate the association of inferior mesenteric arterial (IMA) type II endoleaks in patients undergoing endovascular aortic aneurysm repair (EVAR) for infrarenal abdominal aortic aneurysm with several morphologic parameters. Approval of the institutional ethical review committee was not required. This was a retrospective review of 322 computed tomographic angiographic studies that were performed in patients before they underwent elective EVAR for infrarenal abdominal aortic aneurysm. Morphologic parameters evaluated were IMA patency, origin of the IMA in relation to the aneurysm sac, diameter of the IMA, the cross-sectional area of the contrast material-enhanced aortic lumen at the level of the IMA ostium, and the number of additional patent aortic side branches from the aneurysm sac. The association of IMA type II endoleaks with each variable was analyzed by using univariate and multivariate logistic regression models. The diameter of the IMA did not influence the development of IMA type II endoleaks (P = .51). The incidence of these endoleaks was significantly higher in patients with greater cross-sectional area of the aortic lumen at the IMA ostium (P < .001). Patients with an IMA type II endoleak had significantly more patent aortic side branches before EVAR than did patients without an endoleak (3.6 ± 1.7 vs 2.2 ± 1.4; P < .001). According to the final logistic regression model that included cross-sectional area of the aortic lumen at the IMA and the number of aortic side branches as independent predictors, risk for IMA type II endoleaks was determined with a sensitivity of 78% (39 of 50) and a specificity of 79% (92 of 116). Cross-sectional area of the contrast-enhanced aortic lumen at the level of the IMA ostium and the number of additional patent aortic side branches are associated with the development of IMA type II endoleaks.

Anatomic Risk Factors for Type-2 Endoleak Following EVAR: A Retrospective Review of Preoperative CT Angiography in 326 patients

We describe the anatomic characteristics on preoperative CT angiography (CTA) that predispose to type-2 endoleaks after endovascular aneurysm repair (EVAR) for an abdominal aortic aneurysms (AAA). Between 1999 and 2010, 326 patients had a CTA before and after EVAR. CTAs were reviewed for maximal sac diameter, >50% circumferential luminal thrombus, and patency of the infrarenal aortic side branches, including the inferior mesenteric artery (IMA) and L2-L5 lumbar arteries. Postoperative CTAs were reviewed for a persistent type-2 endoleak. Of 326 patients, 30.4% had a type-2 endoleak on CTA. Univariate analysis demonstrated a patent IMA, increased patent individual L2, L3, and L4 lumbar arteries, and an increased number of total patent lumbar arteries in patients with type-2 endoleak compared to those without (p < 0.001, 0.002, <0.001, <0.001, and <0.001 respectively). Sac diameter, patent L5 lumbar arteries, and >50% circumferential mural thrombus were not significantly different (p = 0.652, 0.617, and 0.16). Univariate logistic regression demonstrated increased risk of endoleak with each additional patent lumbar artery (odds ratio (OR) 1.26, p < 0.001). Multivariate analysis of the 326 patients resulted in the delineation of the optimal anatomic variables that predicted a type-2 endoleak: occluded L3 lumbar arteries (OR 0.1, p = 0.002), occluded L4 lumbar vertebral arteries (OR 0.31, p = 0.034), and IMA occlusion (OR 0.38, p = 0.008). Univariate analysis demonstrated total patent lumbar arteries as a significant predictor of type-2 endoleak. Multivariate analysis demonstrated IMA occlusion, L3 lumbar artery occlusion, and L4 lumbar artery occlusion as independently protective against type-2 endoleak after EVAR.

Technical considerations and results of chimney grafts for the treatment of juxtarenal aneursyms

To present our initial experience and technical considerations for the use of chimney grafts in the treatment of patients that require endovascular aneurysm repair with aortic branch preservation. All patients treated with a chimney procedure between October 2009 and June 2011 were included in our analyses. Chimney procedures were only performed in patients that were unsuitable for open repair and without opportunity to use fenestrated grafts (because of unsuitable anatomy or emergency operation). Open brachial or axillary access was used to deploy covered chimney grafts in the target vessels, and subsequently, a stent graft was deployed via femoral cut-down access. Thirteen patients (12 males; mean age, 77.2 ± 6.2 years; mean maximal diameter, 71.4 ± 10.2 mm) underwent a chimney procedure with the preservation of 22 aortic side branches. Primary technical success was 92.3% due to occlusion of one renal artery within 24 hours. Thirty-day mortality was 0%. Infrarenal mean neck length was 2.6 mm ± 3.2 mm (range, 0-8 mm) and could be extended to 27.3 mm ± 9.9 mm (range, 18-53 mm) by the use of chimney grafts. During follow-up (median, 10.8 months; interquartile range, 7.4-19.4), one patient died from complications from mesenteric ischemia based on a stenosis of the celiac trunk attributable to the bare stent of the stent graft, and one patient died from aneurysm rupture. Other complications included late occlusion of one renal artery and a type II endoleak, which was unsuccessfully treated with coil embolization and required laparotomy. If we disregard the ruptured patient who had an enormous increase of aneurysm diameter, mean aortic aneurysm diameter reduced from 70.7 ± 10.3 mm (range, 54-89 mm) to 66.7 ± 13.9 mm (range, 48-96 mm) during follow-up (P = .13). In three patients, the aneurysm diameter decreased by more than 5 mm and in two patients, the diameter increased by more than 5 mm. The aneurysm diameter remained stable in the other eight patients. Until off-the-shelf fenestrated or branched stent grafts become available, the chimney procedure offers a minimally invasive treatment option in patients requiring aneurysm exclusion with side branch revascularization. Although long-term follow-up has to be awaited, the initial results show that chimney grafts can help to decrease or stabilize the aneurysm diameter in most patients, but aneurysm rupture was not prevented in all patients.

Commentary on ‘Systematic Review and Meta-analysis of the Retroperitoneal Versus the Transperitoneal Approach to the Abdominal Aorta’

In the last few decades the classical open surgical approach for infra-renal aneurysm repair has not undergone major changes. The principle of exposing the aorta, clamping it, and sewing in a vascular graft has not changed significantly. In this meta-analysis, the auteurs claim there may be clinical benefits to performing this surgery via a retroperitoneal (RP) approach. 1 The reduction in mortality of elective infrarenal repairs has been substantial since it was developed. 2 However, this reduction is a result of several factors, such as patient selection, medical treatment, aesthetic techniques, and improved care in intensive care units, and not the surgical technique per se. Traditionally,theRPapproachhasbeenreservedforselective cases as many surgeons feel it is technically more demanding and provides limited access to the aortic side branches. 3 However, several comparative studies demonstrated some advantages over the RP approach. 4,5 In clinical practice the RP approach was used for supra-renal and thoraco-abdominal aneurysms, and usually not for infra-renal aneurysms. In the last 20 years endovascular repair (EVAR) has had a major effect on clinical practice. It not only reduced the operative morbidity and mortality but it also changed open surgical repair. The expanding group of patients undergoing EVAR because of an abdominal aortic aneurysm leaves a morechallenging groupforopen repair.The patientswho are going to undergo open repair often have more aneurysms expanding cranially and involving the renal arteries and visceral vessels, and more often have anatomical variants, such as accessory renal arteries.This group of patients, who areunsuitableforEVAR,canbetreatedbyanRPapproachfar more easily than by a transperitoneal approach. 4 As

Role of aneurysm sac embolization during endovascular aneurysm repair in the prevention of type II endoleak-related complications

The goal of this study was to evaluate the role of intraoperative aneurysm sac embolization during endovascular aneurysm repair (EVAR) using a standard dose of coils and fibrin glue in the prevention of type II endoleak (EII). Two groups were compared: 83 patients underwent standard EVAR during the period 2008-2009 (group A) and 79 patients underwent EVAR during the period 2010-2011 (group B). Computed tomography scans were evaluated with Osirix Pro 4.0 software to obtain aneurysm sac volume. EII rates at the first computed tomography scan follow-up, as well as midterm freedom from EII and freedom from related reintervention, were compared. Preoperative number of patent aortic side branches (inferior mesenteric artery, lumbar arteries, accessory renal arteries), sac thrombus, and sac volume were evaluated for their association with EII in the two groups using multiple logistic regressions. Patient characteristics, Society for Vascular Surgery comorbidity scores (0.85 ± 0.44 vs 0.82 ± 0.46; P = .96), and operative time (185 ± 52 vs 179 ± 49; P = .92) were similar for groups A and B. The first computed tomography scan (≤3 months) revealed a significantly larger number of EIIs in group A than in group B (23% vs 10%; P = .02). Spontaneous EII resolution occurred in 65% of patients in group A and in 79% in group B (P = 1.0), whereas sac volume increased in 25% and 10% (P = .63) of cases, respectively. At 18 months (range, 6 months to 4.4 years), overall mean differences in sac volume shrinkage (27 ± 12 cm(3) vs 25 ± 12 cm(3); P = .19) and freedom from EII (92% vs 96%; P = .33) were similar, whereas freedom from reintervention was significantly lower in group A (93% vs 99%; P = .03) than in group B. Multivariate analysis showed preoperative aneurysm sac volume >125 cm(3) to be the only independent significant predictor of EII (odds ratio, 4.0; 95% confidence interval, 1.5-10.5; P = .005). Although further confirmatory studies are needed, sac embolization during EVAR may be a valid approach to preventing EII and its complications during short- and midterm follow-up. More aggressive intraoperative embolization should be considered for patients with a preoperative aneurysm sac volume >125 cm(3).

PS10. Perioperative Administration of Alvimopan, a Novel Peripherally Acting Mu-opioid Receptor Antagonist, Is Associated with Improved Resource Utilization in Patients Undergoing Open Aortic Surgery

eurysm sac embolization during EVAR (edEVAR) with coils and glue, in the prevention of Endoleak type II (ET2). Methods: Two groups were compared: 85 patients underwent standard EVAR during 2007-2008 (Group A) and 81 patients underwent edEVAR during 2009-2010 (Group B). CT scans were elaborated with the Osirix 4.0 software in order to obtain aneurysm sac volume. ET2 rates at the first CT scan follow-up, as mid-term free from ET2 and free from related reintervention were compared. Preoperative patent number of aortic side branches (IMA, lumbars, accessories renal), thrombus and sac volume were evaluated for their association with ET2 in the two groups, using multivariate analysis. Results: Patients characteristics, Society for Vascular Surgery (SVS) comorbidity score (0.85 0.44 vs 0.82 0.48; P .68) and operative time (185.4 51.8 vs 172.9 50.8;P .99) were similar between group A and B. The first CT scan ( or 2 months) demonstrated significantly higher number of ET2 in group A compared to group B (23.5% vs 9.8%;P .02). Spontaneous ET2 resolution occurred in 65% of patients in Group A and 79% in group B (P 1.0), while sac volume increased in 25% vs 10% (P .63) of cases respectively. At 18 months (range:6 to 24) overall mean difference in sac volume shrinkage (27.2 12.3 cm3 vs 24.8 11.6 cm3; P .19) and free from ET2 (91.8% vs 96.3%; P 0.33) were similar, while free from reintervention was significantly lower in Group A (94.1% vs 98.8%; P .05) compared to Group B. Multivariate analysis showed preoperative aneurysm sac volume 125 cm3 to be the only independent significant predictor of ET2 (OR, 3.64; 95% CI, 1.54 to 8.58; P .003). Conclusions: EdEVAR seems to be a valid approach to prevent ET2 and its complications during short and midterm follow-up. Patients with preoperative aneurysm sac volume higher than 125 cm3 should be considered for a more aggressive intraoperative embolization.

The relationship of preoperative thrombus load and location to the development of type II endoleak and sac regression

Few studies have specifically correlated the amount of thrombus in the aneurysm sac and the presence of type II endoleaks (TIIE). This study examined the correlation of preoperative thrombus load and location to the incidence of TIIE and late sac regression. Prospectively collected data from 266 endovascular aneurysm repair (EVAR) patients were analyzed. Maximum thrombus thickness (MTT) and percentage of the circumference of the aortic wall lined by thrombus (thrombus-lined aneurysm circumference [TLAC]) were determined from preoperative computed tomography angiography (CTA) images at four levels: neck, maximum abdominal aortic aneurysms (AAA) diameter (zone B), zone A (between neck and zone B), and zone C (between zone B and aortic bifurcation). The number of aortic side branches (ASB) was also recorded (inferior mesenteric artery [IMA], accessory renals, lumbar, and middle sacral). Logistic regression was used to determine the association of TIIE with each variable. Thirty-three (12%) early and 32 (13%) late TIIE were noted at a mean follow-up of 22 months (range, 1-87 months). The mean MTT at zone B was 19.7 mm in patients without early TIIE and 18.8 mm in patients without late TIIE vs 14.4 and 17.2 mm in patients with early and late TIIE (P = .0137 and P = .444, respectively). The mean percentage of TLAC was 76% and 75% vs 65% and 64% in patients without vs with early and late TIIE (P = .0329 and P = .044, respectively). There was no correlation of early and late TIIE and thrombus location by zones. The IMA was patent in 7% and 7% of patients without early and late TIIE vs 16% and 15% with TIIE (P = .0367 and P = .077, respectively). The mean number of ASB in patients without (early and late) TIIE was 5.8 and 5.6 vs 5.8 and 7 with endoleak (P = .932 and P = .001, respectively). Univariate analysis showed the following variables decreased the incidence of early TIIE: MTT for zone B (odds ratio [OR] 0.79 for 5-mm increase; P = .014), MTT zone A (OR, 0.78; P = .028), MTT zone C (OR, 0.82; P = .043), and percentage of TLAC (OR, 0.88 for 10% increase; P = .036). For late TIIE: percentage of TLAC (OR, 0.88 for 10% increase; P = .048), and ASB (OR, 1.39 for each additional vessel; P = .001). A multiple regression model showed only ASB (OR, 1.34; P = .009) was a predictor for late TIIE. Four of five patients (80%) with late sac expansion vs 24 of 208 (12%) without expansion had late TIIE (P = .001). MTT, percentage of TLAC, number of ASB, and patent IMA influenced early TIIE; however, only the number of ASB influenced late TIIE.

The chimney procedure is an emergently available endovascular solution for visceral aortic aneurysm rupture

A 79-year-old woman presented with a ruptured saccular thoracoabdominal aortic aneurysm involving the celiac and mesenteric artery. The patient was unfit for open surgical repair. A "chimney" procedure was performed, which involved placement of stents in the aortic side branches alongside the endograft. The patient underwent another chimney procedure 2 weeks later for a type I endoleak. Computed tomography angiography (CTA) at 1 and 6 months showed a good result with no endoleaks or graft migration. The chimney procedure provides an alternative for emergency patients unfit for open repair and has the advantage that stents can be used that are already available in most institutions.

Technical Development and Initial Animal Experience With a Novel, Uncovered, Self-Expanding, Highly Flexible Aortic Stent With Improved Side Branch Access

To present a novel, uncovered, self-expanding aortic stent for use as a thoracoabdominal stent-graft extension to improve distal flow in aortic dissections complicated by malperfusion syndrome and to enhance the remodeling process in the abdominal aorta after thoracic endovascular aortic repair. This aortic prosthesis is a laser cut, self-expanding nitinol stent that is designed to provide an optimal balance between radial support and flexibility to negotiate tortuous arterial anatomy. Undulating circumferential rings provide radial force, while flexibility is achieved through the shape and configuration of the longitudinal connectors that extend from the valley of one ring to the offset peak of the next ring. Delivery and deployment characteristics, in vivo flexibility of the stent, and side branch accessibility through the bare stent struts were evaluated in 4 anesthetized domestic swine weighing 68 to 73 kg. All 11 attempted stent implantations were successful in the 4 pigs using a retrograde transiliac access. The stents were positioned and deployed exactly at the intended target locations and conformed well to the aortic anatomy, even in the tortuous aortic arch, with no evidence of stent kinking or collapse. Overall, 21 major aortic side branches were intentionally covered with the bare stent struts; perfusion was not impaired in any branch vessel. Superselective catheterization of the side branches with coronary guiding catheters through the stent struts was possible for all vessels, as was side branch stenting in 3/3 attempts. This initial feasibility study demonstrates the ability to deploy this novel self-expanding aortic stent in pigs. The high flexibility of the stent allowed conformability with tortuous aortic anatomy. Access to side branches overstented with bare stent struts was excellent. Clinical evaluation of the device is planned for the near future.

Ten-Year Follow-Up of Endovascular Aneurysm Treatment with Talent Stent-Grafts

The purpose of this study was to evaluate the clinical results, complications, and secondary interventions during long-term follow-up after endovascular aneurysm repair (EVAR) and to investigate the impact of endoleak sizes on aneurysm shrinkage. From 1997 to March 2007, 127 patients (12 female, 115 male; age, 73.0 +/- 7.2 years) with abdominal aortic aneurysms were treated with Talent stent-grafts. Follow-up included clinical visits, contrast-enhanced MDCT, and radiographs at 3, 6, and 12 months and then annually. Results were analyzed with respect to clinical outcome, secondary interventions, endoleak rate and management, and change in aneurysm size. There was no need for primary conversion surgery. Thirty-day mortality was 1.6% (two myocardial infarctions). Procedure-related morbidity was 2.4% (paraplegia, partial infarction of one kidney, and inguinal bleeding requiring surgery). Mean follow-up was 47.7 +/- 34.2 months (range, 0-123 months). Thirty-nine patients died during follow-up; three of the deaths were related to aneurysm (aneurysm rupture due to endoleak, n = 1; secondary surgical reintervention n = 2). During follow-up, a total of 29 secondary procedures were performed in 19 patients, including 14 percutaneous procedures (10 patients) and 15 surgical procedures (12 patients), including 4 cases with late conversion to open aortic repair (stent-graft infection, n = 1; migration, endoleak, or endotension, n = 3). Overall mean survival was 84.5 +/- 4.7 months. Mean survival and freedom from any event was 66.7 +/- 4.5 months. MRI depicted significantly more endoleaks compared to MDCT (23.5% vs. 14.3%; P < 0.01). Patients in whom all aneurysm side branches were occluded prior to stent-grafting showed a significantly reduced incidence of large endoleaks. Endoleaks >10% of the aneurysm area were associated with reduced aneurysm shrinkage compared to no endoleaks or <10% endoleaks (Delta at 3 years, -1.8% vs. -12.0%; P < 0.05). In conclusion, endovascular aneurysm treatment with Talent stent-grafts demonstrated encouraging long-term results with moderate secondary intervention rates. Primary occlusion of all aortic side branches reduced the incidence of large endoleaks. Large endoleaks significantly impaired aneurysm shrinkage, whereas small endoleaks did not.

Endovascular repair of infrarenal abdominal aortic aneurysm associated with a horseshoe kidney and graft thrombosis in early follow-up

Endovascular aneurysm repair (EVAR) is a well-established alternative to open surgery. The presented case underwent endovascular therapy of an abdominal aortic aneurysm (AAA) with the anatomical prerequisite of a horseshoe kidney. We describe the technique used, including the embolization of aortic side branches, to avoid endoleaks, and the management of thrombotic complications during follow-up.

Preoperative Assessment of Anatomical Suitability for Thoracic Endovascular Aortic Repair

Endovascular treatment of descending thoracic aortic pathologies requires a preoperatively determined interventional strategy. Its feasibility depends mainly on anatomic factors: the morphology of the proximal and distal fixation sites, the diameter and disease state of the access vessels. These factors represent important predictors of success and the most important exclusion criteria.Current diagnostic evaluation of aortic aneurysm for endovascular repair relies primarily on CT scan associated with 3D-reconstruction to assess the anatomical suitability for endograft implantation. In patients with an inadequate length of the proximal or distal neck, the left subclavian artery or the coeliac trunk can be overstented to effectively exclude thoracic aortic lesions. Deliberate coverage of aortic side branches should be decided prior to the procedure (guided by a extensive anatomical assessment) or carefully be avoided in order to reduce major morbidity, especially cerebral embolization, spinal cord ischemia and ischemic abdominal complications.

The Chimney Graft:A Technique for Preserving or Rescuing Aortic Branch Vessels in Stent-Graft Sealing Zones

To report an alternative to the fenestrated stent-graft for preserving blood flow to side branches in the sealing zones of aortic stent-grafts. A covered stent is deployed parallel to the main aortic stent-graft, protruding somewhat proximally, like a chimney, to preserve flow to a vital side branch covered by the aortic stent-graft. Use of a chimney graft makes it possible to use standard off-the-shelf stent-grafts to instantly treat lesions with inadequate fixation zones, providing an alternative to fenestrated stent-grafts in urgent cases, in aneurysms with challenging neck morphology, and for reconstituting an aortic side branch unintentionally compromised during endovascular repair. This technique has been used successfully in 10 patients, combining chimney grafts in the renal, superior mesenteric, left subclavian, left common carotid, and innominate arteries with stent-grafts in the abdominal (n=6) or thoracic (n=4) aorta. There has been no late chimney graft-related endoleak on imaging studies up to 8 months. The use of chimney grafts is feasible in the renal and superior mesenteric arteries, as well as in the supra-aortic branches, to facilitate stent-graft repair of thoracic or abdominal aortic lesions with inadequate fixation zones.

Aortic Dissection With Aortic Side Branch Compromise: Impact of Malperfusion on Patient Outcome

The purpose of this study was to review the management and clinical outcome of patients with aortic dissection and symptomatic or asymptomatic aortic branch compromise. We identified 104 patients (30.7%) with aortic branch compromise from a group of 339 patients who underwent surgical management of aortic dissection from January 1971 to May 2003. Patients were divided into 2 groups: symptomatic and asymptomatic aortic branch compromise, based on the presence or absence of cerebral, extremity, spinal, renal, and visceral ischemia. Clinical data and outcome were reviewed and compared in both groups. There were 74 male (77%) and 30 female patients with a mean age of 58.5 (range, 23-81) years. Aortic dissection was classified as Stanford type A in 58.7%, acute in 58.7%, and was associated with asymptomatic aortic branch compromise in 44 patients (42.3%) and symptomatic aortic branch compromise in 60 patients (57.7%). Asymptomatic and symptomatic aortic branch compromise, respectively, were distributed in the extremity (30 and 33), carotid (5 and 4), renal (21 and 28), visceral (13 and 8), and spinal (0 and 5) arteries. In the asymptomatic aortic branch compromise group, all patients had aortic graft replacement, and 9 had branch reconstructions. In the symptomatic aortic branch compromise group, treatment was aortic graft replacement (48), open fenestration (6), and endovascular treatment (6). Operative mortality rate was 9.1% (4 of 44) in the asymptomatic and 38.3% (23 of 60) in the symptomatic aortic branch compromise during the 30-year study period (P = .001), decreasing from 35.1% (20 of 57) prior to 1990 to 14.9% (7 of 47) since 1990 (P = .04). In the symptomatic group, operative mortality decreased from 56.7% (17 of 30) to 20% (6 of 30) in the same interval (P = .003). Patients treated in both treatment eras were similar except for less aortic graft replacements and more aortic fenestrations and direct branch reconstructions since 1990. Multivariate analysis revealed symptomatic aortic branch compromise group, treatment prior to 1990, Marfan syndrome, age greater than 70 years, and postoperative complications to be independently associated with increased operative mortality. Asymptomatic aortic branch compromise was not associated with increased operative mortality, but organ malperfusion was an independent risk factor for operative death. The operative mortality significantly decreased since 1990, mostly because of changes in our surgical approach, with less aortic graft replacements and more complication-directed procedures.

Evar and Complex Anatomy: An Update on Fenestrated and Branched Stent Grafts

Endovascular aneurysm repair (EVAR) offers a minimally invasive treatment to patients with improved short-term and similar mid-term results compared to conventional, open repair (OR). EVAR is preferred by patients due to the reduction of surgical trauma. Approximately 20% of patients have aneurysm neck morphology which is inadequate for a standard stent graft and requires the endograft to cross vital aortic side branches to achieve a seal. This chapter describes the evolution of three types of devices, namely the fenestrated and branched stent grafts as well as the chimney grafts. These stent grafts incorporate vital aortic side branches in the repair, thereby increasing the applicability of EVAR which may improve the overall results.

Dynamic Cine-Computed Tomography Angiography Imaging of Standard and Fenestrated Endografts: Differing Effects on Renal Artery Motion

Different endograft configurations (fenestrated, transrenal, infrarenal) may varyingly affect aortic side branch movement. Renal artery motion was evaluated with 64-slice dynamic cine-computed tomography angiography before and after endovascular aneurysm repair in 16 patients (46 renal arteries). Center-of-mass displacement of the renals was determined per heartbeat for before repair for 3 different endografts; differences were compared, with significance at P < 0.5. Preoperative renal artery motion is significant (1.2 [SD 0.5] mm, range, 0.6-2.). Neither transrenal nor infrarenal endografts alter renal artery motion compared with before repair (P < .05). Renal artery motion after fenestrated endovascular repair with renal stents reduces motion to 25% of the preoperative value (0.3 [SD, 0.1] mm, range, 0.2-0.5 mm; P = .01). Endograft implantation without stented side branches does not change renal artery motion, potentially allowing significant movement of the renal artery relative to the fenestration. Routine stenting of fenestrations limits postoperative renal artery motion to 0.3 mm, thereby preventing significant branch movement in relation the fenestration.

Aortitis Following Percutaneous Aortic Side Branch Embolization Prior to Endovascular Repair of Infrarenal Aortic Aneurysm

To report two cases of life-threatening aortic infection after percutaneous endovascular coil embolization prior to endovascular abdominal aortic aneurysm (AAA) repair (EVAR). Two 76-year-old patients were readmitted 5 days and 3 weeks, respectively, after technically successful percutaneous coil embolization of aortic side branches in advance of scheduled EVAR. In the first patient, the right hypogastric artery, the inferior mesenteric artery (IMA), and a lumbar artery had been embolized, whereas in the second patient only the right hypogastric artery and the IMA had been occluded. On admission, both patients presented with severe abdominal pain. Investigations revealed acute aortic infection in both patients, combined with substantial AAA enlargement in one. Open surgical infrarenal aortic replacement was performed using homografts, and antibiotic therapy was initiated. After uneventful recovery, both patients were asymptomatic, had intact aortic homografts, and showed no evidence of infection after 12 and 18 months of follow-up, respectively. Endovascular infections are a potentially serious complication following percutaneous coil embolization of major aortic branches. Early diagnosis and dedicated therapy are mandatory. Immediate resection of the infected aorta and replacement with homografts in association with prolonged antibiotic treatment showed good midterm results.

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.

Comparison of the Fixation Strength of Standard and Fenestrated Stent-Grafts for Endovascular Abdominal Aortic Aneurysm Repair

To determine whether fenestrated stent-grafts provide better stability to resist migration than standard non-fenestrated stent-grafts. Truncated fenestrated stent-grafts with a single fenestration were deployed in bovine aortic segments with a side branch. Balloon-expandable stents were then delivered into the branches. Similarly, standard stent-grafts of the same dimensions were deployed for comparison. The aorta was pressurized to achieve stent-graft oversizing of 5%, 10%, or 20%. The force required to cause distal migration was recorded by a digital force gauge attached to the stent-graft. Displacement of the stent-grafts occurred in 2 distinct phases: an initial yield during which the barbs embedded in the aortic wall and a final displacement leading to significant migration and dislodgement of the device. The displacement force that initiated each phase was dependent upon the degree of oversizing of the stent-graft relative to the aortic diameter. For 5%, 10%, and 20% oversizing, the mean displacement forces in the initial displacement phase were 3.39+/-0.37, 4.32+/-0.63, and 7.69+/-1.18 N, respectively, in non-fenestrated grafts and 10.48+/-1.23, 11.45+/-1.48, 12.12+/-1.42 N in fenestrated grafts. The displacement forces in the final displacement phase were 8.10+/-0.92, 10.76+/-1.74, and 16.82+/-0.92 N for non-fenestrated and 22.56+/-1.60, 28.24+/-1.56, and 33.01+/-1.75 N for fenestrated stent-grafts. The differences in displacement forces between standard and fenestrated stent-grafts were significant for both phases (p<0.001) at all oversizing levels. Improvement in fixation strength was noted with increasing stent-graft oversizing of up to 20%. Fenestrated stent-grafts offer higher ultimate fixation compared to standard devices. However, the ultimate fixation strength was not recruited until an initial phase of short migration occurred as the barbs engaged. While this movement is inconsequential with standard stent-grafts, it has the potential to crush the stents placed into aortic side branches with fenestrated endografts.

In Vivo Antegrade Fenestration of Abdominal Aortic Stent-Grafts

To examine in a canine model the feasibility of antegrade fenestration of abdominal aortic stent-grafts to preserve the patency of the renal arteries. Two large dogs underwent antegrade fenestration of stent-grafts in the perirenal aorta. Before fenestration, bare stents were inserted in both renal arteries as fluoroscopic landmarks. A 12-mm iliac extension served as the canine aortic endograft. The first procedure was done under ultrasound and fluoroscopic guidance, using an intravascular ultrasound (IVUS) probe inserted in the vena cava and a Pioneer IVUS catheter. The second was performed exclusively under fluoroscopic guidance with a Brockenbrough needle. Angiograms and duplex ultrasound were planned for 1 month, after which the dogs would be sacrificed for autopsy. The explanted endograft was subjected to biomaterials analysis, with a focus on fabric tear. Perforation of the aortic graft and catheterization of the renal arteries with a floppy guidewire were possible in both animals. In dog 1, aortic graft dilation and subsequent fenestration were not possible, and the experiment was terminated. However, the procedure was successful in both renal arteries of dog 2. At 1-month follow-up in this dog, both renal arteries were patent. Stent fractures were observed bilaterally. There was no extension of the damage to the fabric beyond the area of fenestration. In vivo antegrade fenestration of aortic endografts is technically feasible. However, improvements in technique, instrumentation, and materials are required to make it a reliable and reproducible way of allowing stent-graft vascularization of aortic side branches.