Fenestrated aortic stent grafts

Chimney endovascular aneurysm repair (ChEVAR) for hostile neck complex aneurysm

OBJECTIVE

Recent guidelines recognize the role of chimney endovascular aneurysm repair (ChEVAR) in the treatment of complex aortic disorders. The optimal configuration and number of visceral vessels that can be incorporated is still controversial. We aim to review outcomes from a multi-institutional decade-long experience with ChEVAR.

METHODS

Patients undergoing ChEVAR with multiple (≥2) chimney branches were selected from a prospectively maintained database at the two academic university hospitals. All patients were poorly suited for fenestrated or branched endograft repair (F/BEVAR) and deemed poor-risk for open surgery.

RESULTS

Forty-nine multiple ChEVAR were performed in 44 men and 5 women, with complete outcome data at a mean follow-up of 18 months. Overall, 2 patients died during follow-up (4%) with no aneurysm-related mortality and two ruptures after ChEVAR (4.1%) due to a type Ib endoleak from iliac limb pullout and persistent gutter-flow, both repaired with endovascular means. No stroke or spinal cord ischemia was noted during the follow-up period. Reintervention was undertaken in eight patients (16.3%) with five reinterventions for persistent gutter-flow and four chimney graft-associated. Three-vessel ChEVAR was performed in 16 patients, with two-vessel ChEVAR in 33 patients for a total of 114 chimney branches (mean 2.3 chimneys per patient). There were 21 superior mesenteric artery (SMA), 45 right renal, 46 left renal artery (LRA), and two accessory LRA chimneys placed. Antegrade configuration of chimney branches was chosen in 43 patients (88%). There were no significant differences between three-vessel and two-vessel ChEVAR upon univariate analysis in aneurysm size (65.6 vs 60.5 mm; p = 0.059), iliac diameter (7.3 vs 7.1 mm; p = 0.85), or endograft oversizing (30 vs 32.5%; p = 0.43). Three-vessel ChEVAR was associated with a larger aneurysm neck diameter (28.4 vs 25.0 mm; p = 0.021), shorter native infrarenal neck (0.5 vs 3.37 mm; p = 0.002) as well as longer seal zone (36.33 vs 22.67 mm; p = 0.005) compared with two-vessel ChEVAR. At follow-up, there were no significant differences in gutter area between three-vessel and two-vessel ChEVAR (18.9 vs 15.7 mm³; p = 0.73) nor the rate of persistent gutter-flow (12.5 vs 9.1%; p = 0.71).

CONCLUSION

Reintervention to multiple chimney grafts and for persistent gutter-flow is higher compared to single chimneys and demands close surveillance. However, based upon this combined transantlantic experience, we believe multiple ChEVAR provides a reasonable and safe option for complex aortic aneurysm repair when open or custom endografts are not available or indicated based on their Instructions For use, even when triple chimney grafts are required. The optimal configuration for multiple ChEVAR still warrants further study, although theoretical preliminary advantages may exist for a combination of antegrade and retrograde chimneys.

Open repair versus evar with parallel grafts in patients with juxtarenal abdominal aortic aneurysm excluded from fenestrated endografting

BACKGROUND

We compared the outcomes of open surgical repair (OSR) versus EVAR with parallel graft technique (PG) in patients with juxtarenal abdominal aortic aneurysm (JAAA) excluded from fenestrated endovascular aortic repair (FEVAR) due to clinical, anatomical, technical or manufacturing time reasons.

METHODS

A single-center analysis of consecutive patients who underwent elective and urgent (within 24-48 hours) repair of JAAA from January 2010 to January 2019 was performed. Two groups were compared: patients excluded from FEVAR and respectively treated by OSR or by PG for JAAA. Perioperative clinical, anatomic and operative data were collected in a dedicated database. The endpoints were primary technical success, changes in renal function, early and long-term mortality, freedom from aortic related reinterventions (ARRs) and aortic related mortality (ARM).

RESULTS

118 consecutive patients were treated for JAAA, 32 of them (27.1%) with FEVAR. 86 patients were enrolled in the study (OSR group=61; PG group= 25). The mean age was 77.4 ± 6.5 years for PG group and 71.1 ± 6.7 years for OSR group (p=.0001); the average comorbidity score of the Society for Vascular Surgery was higher for patients treated by PG (10.2 ± 4.8 vs 5.5 ± 0.4, p=.0001), with no differences for hypertension and renal score. After propensity score matching, 42 patients (OSR=27 ; PG=15) without differences in the preoperative risk factors were selected. Conical shape and neck mural thrombus were respectively more represented in the OSR group (95.1% vs 56.0%; 63.9% vs 36.0%). Aortic clamp site was supraceliac for 12 patients (19.7%), suprarenal for 21 (34.4%) and trans-renal for 28 patients (45.9%). In the PG group, 16 patients (64%) were treated with a single renal chimney. Primary technical success was similar in the two groups (100.0% vs 92.0%, p=.08), with an higher rate of procedure achieved by assisted technical success for the PG group after propensity score matching analysis (20.0% vs 0%, p=.04). Deterioration of renal function occurred for both groups of patients, with a significant creatinine increasing 12 months after surgery in the PG group compared with OSR group (1.72 ± 0.66 vs 1.18 ± 0.40, p=.006). Multiple logistic regression shows no independent predictor of peri-operative medical complication among demographics and pre-operative relevant clinical factors between the two cohorts. No difference in terms of early mortality was observed between the groups (1.6 % vs 0%, p=1.00). At 5 years, overall survival was lower for patients treated by PG (53.5% vs 70.2%, p=.007), such as freedom from ARRs (64.6 vs 90.5%, p=.03). Freedom from ARM at 5 years did not show significant differences among the two groups (100% vs 98.4%, p=1.00).

CONCLUSIONS

PG represents a feasible procedure for patients excluded from FEVAR due to clinical, anatomical, technical or device manufacturing time reasons, ensuring low rates of ARM. However, ARRs during the follow-up remain the Achilles heel of this technique. OSR is still the most durable procedure in the endovascular era, allowing the treatment of proximal "hostile necks" with low rates of reoperation and a similar impact on the renal function compared to PG.

Characterising the incidence and mode of visceral stent failure after fenestrated endovascular aneurysm repair (FEVAR)

Background

In FEVAR, visceral stents provide continuity and maintain perfusion between the main body of the stent and the respective visceral artery. The aim of this study was to characterise the incidence and mode of visceral stent failure (type Ic endoleak, type IIIa endoleak, stenosis/kink, fracture, crush and occlusion) after FEVAR in a large cohort of patients at a high-volume centre.

Methods

A retrospective review of visceral stents placed during FEVAR over 15 years (February 2003-December 2018) was performed. Kaplan-Meier analyses of freedom from visceral stent-related complications were performed. The outcomes between graft configurations of varying complexity were compared, as were the outcomes of different stent types and different visceral vessels.

Results

Visceral stent complications occurred in 47/236 patients (19.9%) and 54/653 stents (8.3%). Median follow up was 3.7 years (IQR 1.7–5.3 years). There was no difference in visceral stent complication rate between renal, SMA and coeliac arteries. Visceral stent complications were more frequent in more complex grafts compared to less complex grafts. Visceral stent complications were more frequent in uncovered stents compared to covered stents. Visceral stent-related endoleaks (type Ic and type IIIa) occurred exclusively around renal artery stents. The most common modes of failure with SMA stents were kinking and fracture, whereas with coeliac artery stents it was external crush.

Conclusion

Visceral stent complications after FEVAR are common and merit continued and close long-term surveillance. The mode of visceral stent failure varies across the vessels in which the stents are located.

A Simple Target Will Save the Day and the Kidney: This Is How We Perform Our Endovascular Fenestrated Graft Procedure

With the advent of state-of-the-art imaging modalities, increasing population age, and advanced preventive medical treatments, medical device design attempts to keep up with procedural demand. An abdominal aortic aneurysm (AAA) is a recognized, potentially fatal disease process where strides have been made in screening, detection, and treatment since its discovery. With the introduction of percutaneous endograft procedures in 1991, open surgical treatment is nearly a lost art. Endovascular aortic repair is now the gold standard. However, short landing zone necks, hostile angulation, and markedly dilated seal zones present challenges for one size fits all endovascular aortic devices. Suprarenal and juxtarenal fenestrated aortic grafts are the most advanced individually customized grafts invented to date. Subsequently, proper placement of these complex devices still presents challenges. We present a method for preoperative renal stent placement for target purposes. This article includes a pictorial guide and describes the tips and pitfalls for easy proper AAA exclusion with a fenestrated aortic graft. We were successful in the deployment of the fenestrated graft device and the exclusion of an aortic aneurysm while preserving the patency of the renal arteries. The patient had no postoperative complications. During 18-month postoperative surveillance, imaging demonstrated proper graft positioning without evidence of an endoleak. In fenestrated endovascular aortic repair, preoperative renal stenting is paramount for targeting purposes. This allows for the precise and timely deployment of the renal limbs through the fenestrations while minimizing the risk of postoperative complications, including renal artery occlusion.

Update on graft infections in thoracoabdominal aortic aneurysm surgery

The incidence of an aortic graft infection following the repair of thoracoabdominal aortic aneurysm, is a rare yet insidious complication which requires prompt recognition and management. The decision-making framework for management encompasses the choice or antimicrobial therapy alone versus pursuing surgical intervention, which can then also lead to considering the potential for allografts. The current literature on the matter is heavily burdened by limitations of the reported retrospective experiences consisting of small patient cohorts. Studies have reported the favored approach of surgical intervention, although statistical significance is not reached. There is a clear recognized impact that the event surrounding the initial repair has on the occurrence of graft infection itself; with emergency repairs, and incidence of nosocomial infection being associated with higher rates of graft infection. We must consider the influencers of this ominous complications, which go back to the perioperative events itself, whether the initial intervention was elective or an emergency, the impact of nosocomial infections, the choice of open versus endovascular for initial repair. Only with the appropriate management strategy that encompasses all these factors, will allow the best treatment to be provided for patients. A sound understanding and appreciation for the aforementioned can allow the stratification of the risk associated with the occurrence of an aortic graft infection, leading to surveillance opportunities to provide the crucial ability to rapidly recognize this complication.

Outcomes after endovascular repair of abdominal aortic aneurysm involving the renovisceral arteries: A multi-center follow-up study

Objectives

To evaluate outcomes after endovascular treatment of abdominal aortic aneurysms (AAA) involving the renovisceral arteries and to compare outcomes after fenestrated/branched endovascular aortic repair (f/b-EVAR), chimney/periscope EVAR (ch-EVAR), and bailout ch-EVAR.

Methods

A retrospective multicenter study including all patients with AAA involving the renovisceral segment, treated with f/b-EVAR, ch-EVAR, or bailout ch-EVAR, between 1 January 2005 and 30 June 2015, in three Swedish vascular centers. Patient charts were reviewed for data. Renovisceral stent graft patency was assessed on follow-up CT. Mortality was cross-checked against the Swedish Population Registry. Bailout ch-EVAR was defined as a perioperative decision of renovisceral endografting, as the artery was accidentally covered, or as the aneurysm neck sealing zone was considered inadequate.

Results

Of the 99 identified patients (76 men; mean age 74 years (range 58–89 years)), 68 underwent f/b-EVAR, 18 ch-EVAR, and 13 bailout ch-EVAR. Follow-up lasted for a median of 3.2 years (Q1, Q3 (2.1, 4.7 years)). Elective surgery comprised 87.9% ( n = 87) of the cases. Six patients died within 30 days, and the 30-day mortality after elective surgery was 4.6% (95% CI, 1.3%–11.4%) overall, 1.6% after f/b-EVAR (95% CI, 0.0%–11.4%), 15.4% after ch-EVAR (95% CI, 1.9%–45.4%), and 10.0% (95% CI, 0.3%–44.5%) after bailout ch-EVAR. During follow-up, there were 16 secondary interventions, of which 75% ( n = 12) were performed within six months after the primary intervention. Compared with f/b-EVAR, ch-EVAR was associated with a higher degree of type 1 endoleaks (1.5% vs. 22.2%, P = 0.001) and re-interventions during follow-up (13.2% vs. 33.3%, P = 0.046). The overall assisted target vessel patency was 96.1% (95% CI, 91.7%–98.6%) at one year and 95.2% (95% CI, 89.2%–98.4%) at two years.

Conclusions

Results after EVAR involving endografting of renovisceral arteries from three centers in Sweden with medium volumes are consistent with results previously reported from centers with larger volumes.

Administration of platelets to ruptured abdominal aortic aneurysm patients before open surgery: a prospective, single-blinded, randomised study

BACKGROUND

In patients undergoing open surgery for a ruptured abdominal aortic aneurysm (rAAA), survivors demonstrate a high platelet count, and proactive administration of platelets (and fresh frozen plasma) appears to influence mortality.

OBJECTIVES

This trial investigated the effect of platelets administered before transport to surgery.

METHODS

In a prospective study design, patients were randomised to receive platelets (intervention; n = 61) or no platelets (control; n = 61) before transport to vascular surgery from 11 local hospitals. The study was terminated when one of the vascular surgical centres implemented endovascular repair for rAAA patients.

RESULTS

Thirty days after surgery, mortality was 36% for patients with intervention vs 31% for controls (P = 0·32). Post-operative thrombotic events (14 vs 15; P = 0·69), renal failure (11 vs 10; P = 0·15) and pulmonary insufficiency (34 vs 39; P = 0·15) were similar in the two groups of patients. No adverse reactions to platelet administration were observed. In addition, length of stay in the intensive care unit was unaffected by intervention.

CONCLUSIONS

For patients planned for open repair of a rAAA, we observed no significant effect of early administration of platelets with regard to post-operative complications and stay in the ICU or in hospital and also no significant effect on mortality.

Complications and Reinterventions After Fenestrated and Branched EVAR in Patients with Paravisceral and Thoracoabdominal Aneurysms

The application of endovascular strategies to treat aneurysms involving the abdominal and thoracoabdominal aorta has evolved significantly since the inception of endovascular aneurysm repair. Advances in endograft technology and operator experience have enabled the management of a wider spectrum of challenging aortic anatomy. Fenestrated endovascular and branched endovascular aneurysm repair represent two technical innovations, which have expanded endovascular treatment options to include patients with paravisceral and thoracoabdominal aortic aneurysms. Although similar in many ways to standard aortic endografts, fenestrated and branched endografts have specific short- and long-term complications due to their unique modular endograft design and their sophisticated deployment mechanisms. This article aims to examine the commonly encountered complications with these devices and the endovascular reintervention strategies.

Long-term follow-up of fenestrated endovascular repair for juxtarenal aortic aneurysm

BACKGROUND

Fenestrated endovascular aneurysm repair (FEVAR) is increasingly being used for juxtarenal aortic aneurysms. The aim of this study was to review long-term results and assess the importance of changing stent-graft design on outcomes.

METHODS

This was a retrospective review of all patients who underwent FEVAR within a single unit over 12 years (February 2003 to December 2015). Kaplan-Meier analysis of survival, and freedom from target vessel loss, aneurysm expansion, graft-related endoleak and secondary intervention was performed. Comparison between outcomes of less complex grafts (fewer than 3 fenestrations) and more complex grafts (3 or 4 fenestrations) was undertaken.

RESULTS

Some 173 patients underwent FEVAR; median age was 76 (i.q.r. 70-79) years and 90·2 per cent were men. Median aneurysm diameter was 63 (59-71) mm and median follow-up was 34 (16-50) months. The adjusted primary technical operative success rate was 95·4 per cent. The in-hospital mortality rate was 5·2 per cent; there was no known aneurysm-related death during follow-up. Median survival was 7·1 (95 per cent c.i. 5·2 to 8·1) years and overall survival was 60·1 per cent (104 of 173). There was a trend towards an increasing number of fenestrations in the graft design over time. In-hospital mortality appeared higher when more complex stent-grafts were used (8 versus 2 per cent for stent-grafts with 3-4 versus fewer than 3 fenestrations; P = 0·059). Graft-related endoleaks were more common following deployment of stent-grafts with three or four fenestrations (12 of 90 versus 6 of 83; P < 0·001).

CONCLUSION

Fenestrated endovascular aneurysm repair for juxtarenal aneurysm is associated with few aneurysm-related deaths in the long term. Significant numbers of secondary interventions are required, but the majority of these can be performed using an endovascular approach.

Snorkel endovascular abdominal aortic aneurysm repair versus fenestrated endovascular aneurysm repair: is it a competition?

The endovascular treatment of juxtarenal abdominal aortic aneurysm (AAA) can be performed by either a standard endovascular stent graft with additional snorkle grafts to aorta branches (snorkel endovascular aneurysm repair) or implantation of a fenestrated stent graft (fenestrated endovascular aneurysm repair). While many vascular surgeons consider snorkel endovascular aneurysm repair and fenestrated endovascular aneurysm repair to be competing techniques or alternate strategies, published procedural outcomes suggest more complementary roles. In this clinical review, the advantages and disadvantages of these two approaches are debated, as much can be learned from both strategies. Because the indications and circumstances for juxtarenal AAA repair vary based on patient-specific comorbidities and anatomy, it is recommended that vascular surgeons have access to, and experience with, both treatment strategies. Based on published outcomes, patient outcomes, stent-graft patency, and re-intervention rates are generally similar and acceptable compared with open AAA repair. We conclude that there is a time and a place for both snorkel endovascular aneurysm repair and fenestrated endovascular aneurysm repair for the endovascular management of juxtarenal and pararenal AAA anatomy.

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).

An in Vitro Twist Fatigue Test of Fabric Stent-Grafts Supported by Z-Stents vs. Ringed Stents

Whereas buckling can cause type III endoleaks, long-term twisting of a stent-graft was investigated here as a mechanism leading to type V endoleak or endotension. Two experimental device designs supported with Z-stents having strut angles of 35° or 45° were compared to a ringed control under accelerated twisting. Damage to each device was assessed and compared after different durations of twisting, with focus on damage that may allow leakage. Stent-grafts with 35° Z-stents had the most severe distortion and damage to the graft fabric. The 45° Z-stents caused less fabric damage. However, consistent stretching was still seen around the holes for sutures, which attach the stents to the graft fabric. Larger holes may become channels for fluid percolation through the wall. The ringed stent-graft had the least damage observed. Stent apexes with sharp angles appear to be responsible for major damage to the fabrics. Device manufacturers should consider stent apex angle when designing stent-grafts, and ensure their devices are resistant to twisting.

Preliminary results of Zenith Fenestrated abdominal aortic aneurysm endovascular grafts

BACKGROUND

Patients with juxtarenal aortic aneurysms who are unfit for open repair may be considered for fenestrated endovascular repair (fenEVAR). We report our initial experience with fenEVAR.

METHODS

We reviewed the data on all our patients receiving fenEVAR for juxtarenal aortic aneurysms.

RESULTS

Eight patients, average age 75 years, underwent fenEVAR. Endografts were designed from details obtained from preoperative computed tomography angiography. There were 6 grafts with superior mesenteric scallops and bilateral renal fenestrations, 1 with bilateral renal scallops, and 1 with a single renal fenestration. All patients survived 30 days. There was no renal failure requiring dialysis. At 10 weeks, 1 patient died from acute intestinal ischemia and multisystem organ failure, and another died from respiratory failure.

CONCLUSIONS

It is feasible to offer fenEVAR to patients who are poor candidates for open repair. However, these procedures are technically challenging. Early outcomes are less favorable than other aortic endovascular procedures.

[Interventional endovascular therapy of infrarenal abdominal aortic aneurysm]

The catheter-based interventional therapy (endovascular aortic repair EVAR) of abdominal aortic aneurysms (AAA) has gained an established place in the spectrum of therapeutic options. The procedure is characterized by low peri-interventional morbidity and mortality. Multislice computed tomography (CT) has a dominant role in defining the correct indications and in selecting an appropriate stent graft prior to the intervention. The rate of acute conversions could be reduced from 2.9 % to 0 % in our own elective patient population since 2010. In our vascular centre the proportion of patients treated by EVAR was 39.5 % (102 out of 258). The procedure is used routinely in patients who have an increased risk for general anesthesia or open surgery due to concomitant diseases. It is also used in patients with a reduced local operability due to prior surgery, abdominal diseases or radiation therapy. Arterial closure devices allow a completely percutaneous approach in a certain group of patients. However, after EVAR a life-long surveillance is mandatory because delayed therapy failure has been described. In younger patients who do not have a higher risk open surgery is still an option. The paper describes techniques, results und complications of EVAR.

How secure is the anastomosis between the proximal and distal body components of a fenestrated stent-graft?

OBJECTIVES

To examine the longitudinal migratory force required to cause disconnection of the bifurcated distal body component from the tubular proximal body of a fenestrated stent-graft.

METHODS

Using a previously reported mathematical model distal distraction forces were calculated prior to performing in vitro pullout testing. The top end of the proximal body and the iliac limbs of the distal body were attached to the grips of a tensile tester via plastic sealing plugs and pneumatic clamps. Channels within the plugs allowed pressurisation of the inside of the stent-graft. Pullout tests were conducted in the vertical plane. Force and displacement data were recorded and tests repeated 8 times at room temperature with the stent-grafts either dry or wet and unpressurized, at 100 mmHg or at 120 mmHg.

RESULTS

The median maximum pullout force was 2.9 N (2.6-4.1) when dry, 3.9 N (3.5-5.4) when wet and unpressurized, 6.3 N (4.8-8.3) when wet and pressurized at 100 mmHg and 6.5 N (4.8-7.2) when wet and pressurized at 120 mmHg. There was a significant difference between pressurized and unpressurized conditions (P < 0.01).

CONCLUSIONS

The force required to distract the distal bifurcated component of a fenestrated stent graft is much lower than the reported proximal fixation strength of both a standard and fenestrated Zenith stent graft. Although this helps protect the fenestrated proximal body from the effects of longitudinal migration forces in vivo the current strength of the body overlap zone may actually be unnecessarily weak and requires careful surveillance in follow up.