Fenestrated endovascular grafts for juxtarenal aortic aneurysms: A step by step technical approach

Increasing Role of Fenestrated and Branched Endoluminal Techniques in the Thoracoabdominal Segment Including Supra- and Pararenal AAA

Fenestrated and branched stent-grafts are being increasingly used to address complex pararenal and thoracoabdominal aortic aneurysms by endovascular means. The present paper describes the current indications, anatomical suitability and techniques of fenestrated and branched stent-grafts in the treatment for pararenal and thoracoabdominal aortic pathologies. Published outcomes with regard to perioperative mortality and morbidity, survival, reinterventions and target vessel patency during follow-up are also presented. Finally, advantages and disadvantages of endovascular repair as compared to open repair are discussed.

The Triple Wire Technique for Delivery of Endovascular Components in Difficult Anatomy

We describe a novel endovascular technique in which three 0.014″ guidewires are placed in parallel through a 0.035″ lumen catheter, in order to create a stiff platform to allow for delivery of 0.035″ profile devices through challenging anatomy. Three illustrative cases are presented: a difficult aortic bifurcation during lower extremity intervention, a tortuous internal iliac artery during placement of an iliac branch device, and salvage of a renal artery after inadvertent coverage during proximal cuff deployment for type 1a endoleak. We also quantify the relative stiffness of the triple 0.014″ wire configuration, using several well-known 0.035″ wires for comparison. The "triple wire technique" is an effective method for tracking endovascular devices through difficult tortuous anatomy, and can be used in a variety of clinical settings. The technique is especially useful when a traditional, stiff 0.035″ wire will not track without "kicking out." Each 0.014″ wire is reasonably soft and traverses the tortuous vessel easily, but when the 3 wires are used together as a rail it provides a stiff enough platform for delivery.

Patient Specific Computer Modelling for Automated Sizing of Fenestrated Stent Grafts

OBJECTIVE

The aim was to validate a computational patient specific model of Zenith® fenestrated device deployment in abdominal aortic aneurysms to predict fenestration positions.

METHODS

This was a retrospective analysis of the accuracy of numerical simulation for fenestrated stent graft sizing. Finite element computational simulation was performed in 51 consecutive patients that underwent successful endovascular repair with Zenith® fenestrated stent grafts in two vascular surgery units with a high volume of aortic procedures. Longitudinal and rotational clock positions of fenestrations were measured on the simulated models. These measurements were compared with those obtained by (i) an independent observer on the post-operative computed tomography (CT) scan and (ii) by the stent graft manufacturer planning team on the pre-operative CT scan. (iii) Pre- and post-operative positions were also compared. Longitudinal distance and clock face discrepancies >3 mm and 15°, respectively, were considered significant. Reproducibility was assessed using Bland-Altman and linear regression analysis.

RESULTS

A total of 195 target arteries were analysed. Both Bland-Altman and linear regression showed good reproducibility between the three measurement techniques performed. The median absolute difference between the simulation and post-operative CT scan was 1.0 ± 1.1 mm for longitudinal distance measurements and 6.9 ± 6.1° for clock positions. The median absolute difference between the planning centre and post-operative CT scan was 0.8 ± 0.8 mm for longitudinal distance measurements and 5.1 ± 5.0° for clock positions. Finally, the median absolute difference between the simulation and the planning centre was 0.96 ± 0.97 mm for longitudinal distance measurements and 4.8 ± 3.6° for clock positions.

CONCLUSION

The numerical model of deployed fenestrated stent grafts is accurate for planning position of fenestrations. It has been validated in 51 patients, for whom fenestration locations were similar to the sizing performed by physicians and the planning centre.

Fenestrated Endovascular Aneurysm Repair versus Snorkel Endovascular Aneurysm Repair: Competing yet Complementary Strategies

Juxtarenal/pararenal aortic aneurysms and type IV thoracoabdominal aneurysms pose particular technical challenges for endovascular repair as they involve the visceral segment in addition to insufficient infrarenal neck for the use of standard endovascular aneurysm repair (EVAR) devices. To overcome these challenges, complex EVAR techniques have been developed to extend the proximal landing zone cephalad with maintaining perfusion to vital aortic branches, thereby broadening the applicability of endografting from the infrarenal to the suprarenal aorta. Complex EVAR can be divided into two broad categories: fenestrated endovascular aneurysm repair (FEVAR) and snorkel EVAR. FEVAR is a valid procedure with the standardized procedure, although it remains as a relatively complex procedure with a learning curve. Given time constraints for the custom fenestrated graft, snorkel EVAR may be an alternative for complex repairs in symptomatic or ruptured patients for whom custom-made endografts may not be immediately available. This article discusses these two most commonly used complex EVAR strategies.

Graft Complexity–Related Outcomes of Fenestrated Endografting for Abdominal Aortic Aneurysms

Purpose: To report the outcomes of fenestrated endovascular aneurysm repair (FEVAR) and compare early and midterm results in relation to stent-graft complexity. Methods: Between August 2006 and December 2014, 141 consecutive patients (mean age 72±7.6 years, range 50–89; 120 men) were treated electively with FEVAR for short-neck, juxtarenal, or suprarenal aortic aneurysms. Forty-five patients treated with stent-grafts featuring renal-only fenestrations were assigned to group A, while 96 patients receiving additional fenestrations for the superior mesenteric and/or celiac arteries were assigned to group B. Technical success, operative mortality and morbidity, target vessel patency, endoleak, reintervention, and survival were compared between the groups. Survival, target vessel stent patency, and reintervention during follow-up were estimated by Kaplan-Meier analysis; the estimates are presented with the 95% confidence interval (CI). Results: Technical success was achieved in 135 (95.7%) patients. Overall 30-day operative mortality was 3.5% (5/141). Perioperative complications occurred in 16 (12.1%) patients. Mean follow-up was 33±23 months. Overall estimated survival was 85.1% (95% CI 79.1% to 91.1%) at 1 year and 75.8% (95% CI 68.2% to 83.5%) at 3 years. Freedom from reintervention was 90.6% (95% CI 85.6% to 95.6%) at 1 year and 79.2% (95% CI 71% to 87.5%) at 3 years. There was no statistically significant difference between the groups in terms of perioperative mortality or morbidity, endoleak, survival, target vessel patency, or reintervention. Conclusion: The use of FEVAR for juxta- and suprarenal aneurysms is associated with low 30-day mortality/morbidity and high midterm efficacy. So far, perioperative and midterm results are not affected by the use of more complex fenestrated designs.

Fenestrated stent grafts for the treatment of complex aortic aneurysm disease: A mature treatment paradigm

The introduction of fenestrated stent grafts (SGs) to treat abdominal aortic aneurysms (AAAs) with short proximal necks began in 1999. Nowadays, the whole visceral aorta can be treated totally by endovascular means. The established use of fenestrated devices to treat complex AAAs as a first-line management option has been previously reported. An up-to-date evaluation of the literature was performed including all types of publications regarding the use of fenestrated technology to repair complex AAAs. Fenestrated repair is now an established alternative to hybrid/chimney/snorkel repairs. However, specific criteria and prerequisites are required for the use and improvement of this method. Multiple device morphologies have been used incorporating the visceral arteries in various combinations. This modular strategy connects different devices (bridging covered stents and bifurcated SGs) with the aortic main body, thus excluding the aneurysm from the circulation. Precise deployment of the fenestrated SG is mandatory for successful visceral vessel revascularization. Accurate SG sizing and customization, a high level of technical skill, and facilities with modern imaging techniques including 3D road mapping and dedicated hybrid rooms are required. Most experience has been with the custom-made Zenith Cook platform, although off-the-shelf devices have been recently implanted. More complex repairs have been performed over the last few years, but device complexity has also increased. Perioperative, mid-term, and a few recently reported long-term results are encouraging. Secondary interventions remain the main problem, similar to that observed after traditional endovascular abdominal aortic aneurysm repair (EVAR).

Examination of near-wall hemodynamic parameters in the renal bridging stent of various stent graft configurations for repairing visceral branched aortic aneurysms

OBJECTIVE

This study examined the flow behavior of four stent graft configurations for endovascular repair of complex aneurysms of the descending aorta.

METHODS

Computational fluid dynamics models with transient boundary conditions and rigid wall simplifying assumptions were developed and used with four distinct geometries to compare various near-wall hemodynamic parameters.

RESULTS

Graphic plots for time-averaged wall shear stress, oscillating shear index, and relative residence time were presented and compared among the four stent graft configurations of interest.

CONCLUSIONS

Abrupt 90° and 180° changes in stent geometry (particularly in the side branches) cause a high momentum change and thus increased flow separation and mixing, which has significant implications in blood flow characteristics near the wall. By comparison, longer bridging stents provide more gradual changes in momentum, thus allowing blood flow to develop before reaching the target vessel.

A propensity-matched comparison of outcomes for fenestrated endovascular aneurysm repair and open surgical repair of complex abdominal aortic aneurysms

OBJECTIVE

The benefit of fenestrated endovascular aortic aneurysm repair (FEVAR) compared with open surgical repair (OSR) of complex abdominal aortic aneurysms (CAAAs) is unknown. This study compares 30-day outcomes of these procedures from two high-volume centers where FEVAR was undertaken for high-risk patients.

METHODS

Patients undergoing FEVAR with commercially available devices and OSR of CAAAs (total suprarenal/supravisceral clamp position) were propensity matched by demographic, clinical, and anatomic criteria to identify similar patient cohorts. Perioperative outcomes were evaluated using univariate and multivariate methods.

RESULTS

From July 2001 to August 2012, 59 FEVAR and 324 OSR patients were identified. After 1:4 propensity matching for age, gender, hypertension, congestive heart failure, coronary disease, chronic obstructive pulmonary disease, stroke, diabetes, preoperative creatinine, and anticipated/actual aortic clamp site, the study cohort consisted of 42 FEVARs and 147 OSRs. The most frequent FEVAR construct was two renal fenestrations, with or without a single mesenteric scallop, in 50% of cases. An average of 2.9 vessels were treated per patient. Univariate analysis demonstrated FEVAR had higher rates of 30-day mortality (9.5% vs. 2%; P = .05), any complication (41% vs. 23%; P = .01), procedural complications (24% vs. 7%; P < .01), and graft complications (30% vs. 2%; P < .01). Multivariable analysis showed FEVAR was associated with an increased risk of 30-day mortality (odds ratio [OR], 5.1; 95% confidence interval [CI], 1.1-24; P = .04), any complication (OR, 2.3; 95% CI, 1.1-4.9; P = .01), and graft complications (OR, 24; 95% CI, 4.8-66; P < .01).

CONCLUSIONS

FEVAR, in this two-center study, was associated with a significantly higher risk of perioperative mortality and morbidity compared with OSR for management of CAAAs. These data suggest that extension of the paradigm shift comparing EVAR with OSR for routine AAAs to patients with CAAAs is not appropriate. Further study to establish proper patient selection for FEVAR instead of OSR is warranted before widespread use should be considered.

Open and endovascular repair of juxtarenal abdominal aortic aneurysms: a systematic review

This systematic review focuses on the 30-day mortality associated with open surgery and fenestrated endografts for short-necked (<15 mm) juxtarenal abdominal aortic aneurysms. A search for studies published in English and indexed in the PubMed and Medline electronic databases from 2002 to 2012 was performed, using "juxtarenal abdominal aortic aneurysm" and "treatment" as the main keywords. Among the 110 potentially relevant studies that were initially identified, eight were in accordance with the inclusion criteria in the analysis. Similar outcomes for open and endovascular repair were observed for 30-day mortality. No differences were observed regarding the secondary outcomes (duration of surgery, hospital stay, postoperative renal dysfunction and late mortality), except that the late mortality rate was significantly higher for the patients treated with open repair after a median follow-up of 24 months. Fenestrated endografting is a viable alternative to conventional surgery in juxtarenal abdominal aortic aneurysms with a proximal neck <15 mm.

Fenestrated endovascular repair of complex aortic aneurysms

BACKGROUND

Fenestrated endovascular aneurysm repair (FEVAR) provides an endovascular solution for patients with large abdominal aortic aneurysms and challenging neck anatomy in addition to repair of endoleaks and pseudoaneurysms. This article reports the midterm outcomes of FEVAR from a single-tertiary referral centre in Ireland.

METHODS

From 2006 to 2012, nine consecutive asymptomatic patients with neck anatomy unfavourable for standard EVAR underwent endovascular repair with a customised fenestrated Zenith stent graft. An additional three patients had fenestrated grafts for repair of pseudoaneurysms (n = 2) following open AAA repair and a type I endoleak (n = 1). All patients were prospectively enrolled in a computerised database. Outcomes including mortality, morbidity, renal function, target vessel patency, endoleak and reintervention were analysed.

FINDINGS

The mean age and aneurysm size in the primary repair group were 74 years (65-84 years) and 6 cm (5-8.3 cm), respectively, and in the secondary repair group, the mean age was 66 years (61-75 years). No procedures required open conversion, and no visceral arteries were lost. On completion angiography, two patients in group 1 had a type I endoleak and one had a type III endoleak. There were no endoleaks in the secondary repair group. Follow-up ranged from 30 days to 6 years. There was one death within 30 days (8 %) and two deaths at 3 years from non-aneurysm-related causes. Six patients required secondary interventions. Three patients had a transient post-operative creatinine rise of >30 %.

CONCLUSION

Our study supports FEVAR as a feasible and effective therapy in the management of patients with complex aortic aneurysms.

Tortuous iliac systems--a significant burden to conventional cannulation in the visceral segment: is there a role for robotic catheter technology?

PURPOSE

To attempt to quantify the effect of varying degrees of iliac tortuosity on maneuverability and "torquability" of endovascular catheters in the visceral segment, comparing conventional and robotic cannulation techniques.

MATERIALS AND METHODS

In a fenestrated endograft within a pulsatile phantom, 10 experienced operators cannulated the renal arteries via three different access vessels of varying iliac tortuosity with the use of conventional and robotic techniques. All procedures were performed in the angiography suite and recorded for blinded video assessment for quantitative (time, catheter-tip movements) and qualitative metrics (operator performance scores).

RESULTS

In total, 120 cannulations were observed. With increasing iliac tortuosity, median time and number of catheter movements required for renal cannulation with conventional techniques increased in stepwise fashion for mild, moderate, and severe iliac tortuosity (times, 7.6 min [interquartile range (IQR), 4.6-9.3 min] vs 6.9 min [4.2-11.4 min] vs 17.7 min [13.3-22.6 min], respectively; movements, 184 [IQR, 110-351] vs 251 [207-395] vs 569 [409-616], respectively). Median renal cannulation times were significantly reduced with the use of the robotic system irrespective of mild, moderate, or severe tortuosity (times, 1.4 min [IQR, 1.1-1.9 min] vs 3 min [2.3-3.3 min] vs 2.8 min [1.5-3.9 min], respectively; movements, 19 [IQR, 14-27] vs 46 [43-58] vs 45 [40-66], respectively; P < .005). Overall operator performance scores improved significantly with the use of the robotic system irrespective of iliac tortuosity severity.

CONCLUSIONS

In cases of moderate to severe iliac tortuosity, conventional catheter manipulation and control becomes an issue. The improvement in positional control and predictability seen with advanced catheter designs may be amplified in cases of severe iliac tortuosity.

Initial experience of branched endovascular graft for abdominal aortic aneurysm with complex anatomy of proximal neck: planning and technical considerations

The purpose of this report was to demonstrate initial Japanese cases of abdominal aortic aneurysm (AAA) with complex anatomy of proximal neck treated using a Zenith fenestrated endograft with branched endovascular technique and to describe the device's design and technical considerations. Planning and sizing of endografts were performed using high-resolution computed tomography on a three-dimensional workstation. Branched endograft technique combined with reinforced fenestrated device and balloon-expandable stent graft was used in two patients because of challenging morphology for the fenestrated device with a bare stent. Successful exclusion of the aneurysm sac was achieved in both patients with antegrade perfusion in incorporated visceral vessels. Endovascular repair using a fenestrated device with graft material incorporating the visceral arteries is feasible. The combination of the reinforced fenestration and the balloon-expandable stent graft can provide an adequate sealing effect for the compromised anatomy. Initial and midterm results are reported with further follow-up and patient accrual.