Endovascular chimney technique for juxtarenal abdominal aortic aneurysm: a systematic review using pooled analysis and meta-analysis

"Octafen": A Noninvestigational Alternative Endograft Configuration for the Treatment of Thoracoabdominal Aortic Aneurysms

PURPOSE

To demonstrate the feasibility of Octafen technique, a novel endovascular configuration for the treatment of thoracoabdominal aortic aneurysms (TAAA).

TECHNIQUE

Two patients with complex TAAA and high surgical risk were treated with Octafen endograft configuration in a hybrid operating room with computed tomography (CT)-fluoroscopy image fusion guidance, using 3D-3D fusion techniques to facilitate procedural success. The procedure is a modification of the previously-described Octopus technique for endovascular repair of TAAA. The main advantage of this technique is the ability to use devices to repair a TAAA with the combination of off-the-shelf and noninvestigational custom-made devices. The devices used are readily available to most practicing vascular surgeons, which provides an alternative treatment in case of limited access to investigational devices, in time-sensitive cases, and in patients with limited functional capacity who cannot undergo open repair. In the modification described herein, we use a combination of standard bifurcated endovascular aneurysm repair (EVAR) devices (Excluder; W.L. Gore & Associates, Flagstaff, Arizona) in combination with a 2-vessel renal fenestrated device (Z-Fen; Cook Medical, Bloomington, Indiana). The article describes a step-by-step approach to this technique to elucidate pitfalls, benefits, and advantages.

CONCLUSION

The Octafen technique might offer an alternative option for thoracoabdominal aneurysm treatment circumventing the need for access to custom-made, investigational devices.

CLINICAL IMPACT

In this manuscript, we describe a technique for endovascular repair of thoraco-abdominal aortic aneurysms that involves the combination of off-the-shelf and non-investigational, custom-made devices. The 'Octafen' technique provides a treatment alternative in case of limited access to investigational devices and can be adjusted according to patient anatomy.

Mid-Term Outcomes of Chimney Endovascular Aortic Aneurysm Repair: A Systematic Review and Meta-analysis

BACKGROUND

To provide an overview of the literature on the mid-term outcomes of chimney EVAR (ChEVAR) for the treatment of juxtarenal abdominal aortic aneurysms (JAAA).

METHODS

Different electronic databases were searched for published articles up to January 2020. The eligibility criteria were studies describing mid- or long-term outcomes of chimney EVAR (mean follow-up at least 1 year) for treatment of JAAA, including more than 10 cases, published in English, and with full text available. The outcomes measure were overall survival rate, target vessel patency, and freedom from reintervention at 3 years. Quality of the included studies was analyzed using the MINORS criteria. Pooled effect estimates were analyzed using random-effect models and heterogeneity was tested using I² statistics.

RESULTS

Thirteen articles met the inclusion criteria. The included studies described 1,019 patients. According to the quality assessment, methodological quality was moderate to poor. The pooled overall survival, freedom from reintervention, and target vessel patency at 3 year was 81.4 % (95%CI 73.8-87.9), 85.7% (95%CI 75.6-93.5), and 95.1% (95%CI 89.3-98.7) respectively.

CONCLUSIONS

The results of this review show good to acceptable short and mid-term survival and good mid-term durability, which supports that ChEVAR as a suitable alternative in high-risk JAAA. However, proper patient selection for ChEVAR seems essential to attain good mid-term outcomes, and further large prospective and good quality studies are required to demonstrate its long-term results and enable conclusions on specific determinants for outcome.

Use of Chimney Technique Does Not Improve the Outcome of Endovascular Aneurysm Repair in Patients With a Hyperangulated and Short Proximal Aortic Neck

PURPOSE

We hypothesized that extending the proximal landing zone with the chimney technique could be beneficial in patients with a hyperangulated proximal aortic neck, defined as more > 60 degrees.

MATERIAL AND METHODS

We retrospectively analyzed the outcome of prospectively collected data of patients treated by endovascular aneurysm repair (EVAR) for infrarenal aortic aneurysm with a hyperangulated proximal aortic neck. In all, 104 out of 130 patients were treated without (Group A) and 24 with the chimney endovascular aortic repair (ChEVAR, Group B). Primary outcome was technical and clinical success according to the reporting standards of the Society of Vascular Surgery.

RESULTS

The use of the chimney technique was associated with a significantly longer operation duration (167 vs. 93 min, p < .001), longer fluoroscopy time (44 vs.30 min, p = < .001), and larger amount of contrast medium used (149 vs. 127 ml, p = .03) but did not significantly improve technical (79.2% vs. 87.7%) and clinical success (54.2% vs. 68.9%). Aneurysm-related mortality was higher in group B (8.3% vs. = 0%, p < .001). Type IA endoleak was high in both groups at completion angiography (11.3% in Group A vs. 12.5% in Group B) and at follow-up (10.4% in Group A vs. 4.5% in Group B) without significant difference between the groups.

CONCLUSIONS

Our data did not show a benefit of the primary use of the chimney technique in patients with a hyperangulated and short neck, although more studies are required to support this conclusion. Other strategies or new technologies are required for improving EVAR results in aneurysm patients with severe angulated proximal and short neck.

Current status on aortic endografts

Endovascular treatment has become widespread to treat aneurysmal disease, especially located in the aorta. The modern era of abdominal aortic aneurysm repair started between 1986 and 1991, and in the last 30 years, Endovascular Treatment for abdominal aortic aneurysms evolved both due to the development of new materials and devices and the increasing appeal and effectiveness of the endovascular therapy itself. Vascular surgeons are using nowadays different solutions of Endovascular Treatment to treat all the expressions of aortic pathology (aneurysms, dissections and trauma) both in the acute and elective setting. Despite its use in every location of the aorta (the ascending aorta, the aortic arch, the thoracic aorta, thoraco-abdominal aorta, pararenal, iuxtarenal and infrarenal aortic aneurysms and iliac aneurysms), its safety and efficiency, endovascular treatment for aortic aneurysms presents some drawbacks: despite a lower short-term morbi-mortality, reinterventions and long-term patency are higher compared to open repair. In this review, we detail the most used types of endografts according to location, their performances and durability for each device. We conclude by discussing options to overcome ET limitations. Therefore, an obvious question arises: what we need in the future? What can the technological progress gives to physicians to further improve this new way of treating aorta?

Evolving Utility of Endovascular Treatment of Juxtarenal, Pararenal, and Suprarenal Abdominal Aortic Aneurysms Associated With Increased Risk of Mortality Over Time

BACKGROUND

Continued advances in endovascular technologies are resulting in fewer open abdominal aortic aneurysm (AAA) repairs. In addition, more complex juxtarenal, pararenal, and suprarenal (JPS) AAAs are being managed with various endovascular techniques. This study sought to evaluate the evolving trends in endovascular aneurysm repair (EVAR) of AAAs, hypothesizing increased rate of JPS AAA repair by EVAR. We also sought to evaluate the risk for morbidity and mortality for EVAR and open aneurysm repair (OAR) of JPS AAAs over time.

METHODS

The 2011-2017 American College of Surgeons National Surgical Quality Improvement Program Procedure-Targeted Vascular database was queried for patients undergoing OAR or EVAR for AAAs. A multivariable logistic regression analysis was performed for both infrarenal and JPS AAA repairs.

RESULTS

Of 18,661 patients who underwent AAA repair, 3,941 (21.1%) were OAR and 14,720 (78.9%) were EVAR. The rate of OAR decreased from 29.5% in 2011 to 21.3% in 2017 (P < 0.001) with a geometric-mean-annual decrease of 27.8%. The rate of EVAR increased from 70.5% to 78.7% during the same time period (P < 0.001) with a geometric-mean-annual increase of 11.6%. These trends remained true for both infrarenal and JPS AAAs. After adjusting for covariates, there was no difference in associated risk of 30-day mortality, renal complications, or ischemic colitis for either OAR or EVAR over each incremental year for infrarenal AAAs (P > 0.05). However, in patients undergoing EVAR for JPS AAAs, the associated risk of mortality increased with each incremental year (odds ratio [OR]: 1.30, confidence interval [CI]: 1.01-1.69, P = 0.039), whereas there was no difference in the risk of mortality for OAR of JPS AAAs with each incremental year (OR: 1.11, CI: 0.99-1.23, P = 0.067).

CONCLUSIONS

The rate of OAR for AAA has decreased over the past seven years with an increase in EVAR, particularly for more complex JPS AAAs. The associated risk for morbidity and mortality for treatment of infrarenal AAAs was not significantly affected by this increased utility of EVAR. The associated risk of mortality for JPS AAAs treated by EVAR increased over time, whereas this trend for associated risk of mortality was not seen for OAR of JPS AAAs. These findings, especially the increased associated risk of mortality over time with EVAR for JPS AAAs, warrant careful prospective analysis.

Concomitant Renal Artery and Aortic Aneurysm: Is Endovascular Surgery the Correct Approach?

Our case illustrates the concomitant presence of a giant aneurysm of the left renal artery at the ostium and an abdominal aortic aneurysm, in presence of a complex aortic anatomy. Type of approach and timing of the treatment is still not well established for the rare coexistence of these 2 pathologies. In case of surgical high-risk patients, endovascular therapy is considered now the best choice to exclude arterial and aortic aneurysms although there are chances to do further interventions in the follow-up. For this reason, we simultaneously treated both the aneurysms through an embolization with plugs and coils of renal aneurysm and endovascular exclusion of aortic aneurysm; in the follow-up, renal function of the patient worsened until hemodialysis and we saw the reperfusion of renal aneurysm and the onset of endoleak I type A from above the aortic and renal aneurysm and B from iliac legs of the previous endograft. We performed a parallel graft technique on visceral vessels to exclude the refilling of both aneurysms and preserve visceral vascularization. Follow-up at 12 months showed the complete exclusion of the aneurysms and the patency of stents in celiac trunk and superior mesenteric artery.

Hemodynamics and Oxygen Transport through Pararenal Aortic Aneurysm Treated with Multilayer Stent: A Numerical Study

BACKGROUND

As opposed to an endoluminal stent graft, a multilayer stent (MS) consists of a porous mesh, which allows for the possibility of treating pararenal aortic aneurysms (PRAAs) that involve a significant branch vessel. However, the choice of the density of the MS plays a vital role in isolating the aneurysm and allowing unobstructed blood flow in the branch vessel.

METHOD

In the present study, we examined 3 cases (without a stent and with single-layer and double-layer stents) via numerical simulations to explore the feasibility of the MSs used in the treatment of such aneurysms and estimate whether there is a more appropriate or optimal stent density.

RESULTS

With stent intervention, the velocity of blood flow in the sac decreased, but the pressure on the surface of the aneurysm did not decrease although it became more uniform. In addition, the "region of double low" (with low wall shear stress and a low Sherwood number) enlarged after stent implantation. Even with the double-layer stent, however, the flux of the branch vessel was still above normal, and we could predict that the optimal stent porosity was approximately 49.9%.

CONCLUSIONS

Unlike in previous studies, an MS could not be feasibly applied to high-risk PRAAs. However, an MS can induce sac thrombosis in the later stages while maintaining visceral vessel patency, and our results suggest that the optimal stent may be a 4-layer stent.

Endovascular Treatment of Various Aortic Pathologies: Review of the Latest Data and Technologies

The technologies and innovations applicable to endovascular treatment for complex aortic pathologies have progressed rapidly over the last two decades. Although the initial outcomes of an endovascular aortic repair have been excellent, as long-term data became available, complications including endoleaks, endograft migration, and endograft infection have become apparent and are of concern. Previously, the indication for endovascular therapy was restricted to descending thoracic aortic aneurysms and abdominal aortic aneurysms. However, its indication has expanded along with the improvement of techniques and devices, and currently, it has become possible to treat pararenal aortic aneurysms and Crawford type 4 thoracoabdominal aortic aneurysm (TAAA) using the off-the-shelf devices. Additionally, custom-made devices allow for the treatment of arch or more extensive TAAAs. Endovascular treatment is applied not only to aneurysms but also to acute/chronic dissections. However, long-term outcomes are still unclear. This article provides an overview of available devices and the results of endovascular treatment for various aortic pathologies.

In Vitro Quantification of Gutter Formation and Chimney Graft Compression in Chimney EVAR Stent-Graft Configurations Using Electrocardiography-Gated Computed Tomography

Purpose: To assess the dynamic behavior of chimney grafts during the cardiac cycle. Methods: Three chimney endovascular aneurysm repair (EVAR) stent-graft configurations (Endurant and Advanta V12, Endurant and Viabahn, and Endurant and BeGraft) were placed in silicone aneurysm models and subjected to physiologic flow. Electrocardiography (ECG)-gated contrast-enhanced computed tomography was used to visualize geometric changes during the cardiac cycle. Endograft and chimney graft surface, gutter volume, chimney graft angulation over the center lumen line, and the D-ratio (the ratio between the lengths of the major and minor axes) were independently assessed by 2 observers at 10 time points in the cardiac cycle. Results: Both gutter volumes and chimney graft geometry changed significantly during the cardiac cycle in all 3 configurations (p<0.001). Gutters and endoleaks were observed in all configurations. The largest gutter volume (232.8 mm3) and change in volume (20.7 mm3) between systole and diastole were observed in the Endurant-Advanta configuration. These values were 2.7- and 3.0-fold higher, respectively, compared to the Endurant-Viabahn configuration and 1.7- and 1.6-fold higher as observed in the Endurant-BeGraft configuration. The Endurant-Viabahn configuration had the highest D-ratio (right, 1.26–1.35; left, 1.33–1.48), while the Endurant-BeGraft configuration had the lowest (right, 1.11–1.17; left, 1.08–1.15). Assessment of the interobserver variability showed a high correlation (intraclass correlation >0.935) between measurements. Conclusion: Gutter volumes and stent compression are dynamic phenomena that reshape during the cardiac cycle. Compelling differences were observed during the cardiac cycle in all configurations, with the self-expanding (Endurant–Viabahn) chimney EVAR configurations having smaller gutters and less variation in gutter volume during the cardiac cycle yet more stent compression without affecting the chimney graft surface.

Aortic aneurysm endovascular treatment with the parallel graft technique from the aortic arch to the iliac axis

BACKGROUND

The chimney technique has been developed for the treatment of complex aortic aneurysms. We analyzed the midterm to long-term outcomes of this approach from a single-center experience.

METHODS

From October 2008 to July 2016, 58 patients underwent endovascular aortic aneurysm repair using the chimney technique. Indications for treatment were thoracic aortic aneurysm (TAA) (N.=11), thoracoabdominal aortic aneurysm (TAAA) (N.=2), pararenal aortic aneurysm (PAAA) (N.=15), aortoiliac/isolated hypogastric artery aneurysm (N.=25), type I endoleak after previous TEVAR/EVAR (N.=4), proximal pseudoaneurysm after AAA open repair (N.=1). Elective (82.8%) and emergent (17.2%) procedures were included.

RESULTS

The immediate technical success was 100%. Single, double and triple chimneys were performed in 46, 10, and two patients, respectively. Overall, 61 target vessels (three left common carotid arteries, eight left subclavian arteries, three celiac trunks, three superior mesenteric arteries, 19 renal arteries and 25 hypogastric arteries) were involved. Postoperative mortality was 0. No neurologic complications were registered. Primary patency rate of the chimney stent/stent graft was 98.3%. Low-flow type I endoleak was observed in four patients (6.9%). Postoperative chimney graft re-intervention rate was 1.7%. The median follow-up was 32±20 months (range 3-96 months). Overall estimated survival at 12, 50, and 80 months was 100%, 89% and 44%, respectively. Estimated freedom from endoleak at 1, 12, 24, and 36 months was 96.5%, 95%, 95%, and 93%, respectively. One hypogastric artery stent-graft occluded at the 3rd month of follow-up. No reintervention was performed.

CONCLUSIONS

Our experience with the chimney technique for aortic aneurysms from the aortic arch to the iliac axis shows promising and durable mid- and long-term results. Endograft oversizing, associated with the chimney graft diameter and length choice remain fundamental to reduce the risk of the most frequent procedure complications: type I endoleak and CG occlusion. The wider use of this technique should be justified in patients considered at high risk for open repair and/or not suitable for the custom-made branched/fenestrated endografts.

Classification of gutter type in parallel stenting during endovascular aortic aneurysm repair

OBJECTIVE

Gutters can be described as the loss of continuous apposition between the main body of the endograft, the chimney stent graft, and the aortic wall. Gutters have been associated with increased risk of type IA endoleaks and are considered to be the Achilles' heel of chimney endovascular aneurysm repair (ch-EVAR). However, there is no classification yet to classify and quantify gutter types after ch-EVAR.

METHODS

Different gutter types can be distinguished by their morphologic appearance in two- and three-dimensional views and reconstructed slices perpendicular to the center lumen line.

RESULTS

Three main categories are defined by (1) the most proximal beginning of the gutter, (2) the length of gutter alongside the endograft, and (3) its distal end. Type A gutters originate at the proximal fabric of an endograft, type B gutters originate as loss of apposition of the chimney stent graft in the branch vessel, and type C gutters start below the fabric of the endograft. To determine eventual changes of gutter size during follow-up computed tomography angiograms (CTAs), measurements may be performed with dedicated software on the follow-up CTA scan to assess the extent of gutters over the aortic circumference, ranging from 0° to 360° of freedom, together with the maximum gap between the endograft material and the aortic wall as it appears on reconstructed axial CTA scan slices.

CONCLUSIONS

The proposed gutter classification enables a uniform nomenclature in the current ch-EVAR literature and a more accurate risk assessment of gutter-associated endoleaks. Moreover, it allows monitoring of eventual progression of gutter size during follow-up.

A Case of Successful Coil Embolization for a Late-Onset Type Ia Endoleak after Endovascular Aneurysm Repair with the Chimney Technique

Juxtarenal aortic aneurysms (JRAAs) are challenging to treat by endovascular aneurysm repair (EVAR) procedures. The chimney technique with EVAR (Ch-EVAR) is one of the feasible and less invasive treatments for JRAAs. However, the main concern of Ch-EVAR is the potential risk of “gutters,” which can lead to type Ia endoleak (EL). Most type Ia ELs after Ch-EVAR procedures occurred intraoperatively, and these ELs could be treated using an endovascular technique. However, late-onset type Ia ELs could be extremely rare, which might have a fear of conservative treatment. Type Ia ELs are associated with an increased risk of aneurysm rupture; therefore reintervention is recommended as soon as possible, and we should be aware of the occurrence of type Ia ELs after the Ch-EVAR procedure.