The Best Conditions for Parallel Stenting During EVAR: An In Vitro Study

In vitro quantification of stent-graft behaviour during chimney thoracic endovascular aortic repair

OBJECTIVE

To quantify dynamic gutter phenomena and endograft deformations during double chimney thoracic endovascular aortic repair (ch-TEVAR) in a physiological model of the thoracic aorta subjected to pulsatile haemodynamic conditions.

METHODS

Two in vitro procedures revascularizing the brachiocephalic trunk and left common carotid artery were performed representing both balloon-expandable (BE, Ankura-BeGraft) and self-expandable (SE, Ankura-Viabahn) double ch-TEVAR configurations. Retrospectively gated computed tomography (CT) was used to evaluate endograft behaviour. Device interactions were characterised according to gutter volume, gutter surface deviation, and endograft deformation (D-ratio) at end-diastolic and peak-systolic aortic pressure.

RESULTS

Use of BE chimney grafts resulted in three times total gutter volume compared to SE chimney grafts. Gutter volumes were observed to vary dynamically between the end-diastolic and peak-systolic phases of the cardiac cycle, with the most substantial change associated with the BE configuration. Chimney graft deformations were dependent on device type, with SE devices exhibiting up to twice the deformation as BE devices. When adjacent, SE chimney grafts were observed to support each other, and thus tended towards a more consistently circular shape.

CONCLUSION

Gutter and chimney graft behaviour were dependent on device type, and exhibited both spatial and temporal variability. This study emphasises notable differences between BE and SE double ch-TEVAR configurations which should be considered when evaluating risk of endoleak. The findings reported here also support the use of gated CT to better identify device-related complications with ch-TEVAR, and can be used in the design of next generation devices.

Long-term outcomes of chimney endovascular aneurysm repair procedure for complex abdominal aortic pathologies

OBJECTIVE

The aim of this study was to update our earlier experience and to evaluate long-term outcomes of chimney endovascular aortic repair performed for selected cases with complex abdominal aortic aneurysm.

METHODS

A single-center retrospective cohort study was conducted on 51 consecutive patients who underwent chimney endovascular aortic repair procedure, deemed unfit for open surgical repair and fenestrated endovascular aneurysm repair, from October 2009 to November 2019. Kaplan-Meier analyses were used to assess the estimated overall survival, freedom from aneurysm related mortality, freedom from reintervention, freedom from target vessel instability, and freedom from type Ia endoleaks.

RESULTS

Fifty-one patients (mean age, 77.1 ± 7.5 years) with a mean preoperative maximum aneurysm diameter of 74.2 ± 20.1 mm were included. Mean follow-up duration was 48.6 months (range, 0-136 months). Estimated overall survival at 5 and 7 years was 36.3% ± 7.1% and 18.3% ± 6.0%, respectively. Freedom from aneurysm-related mortality was 88.6% ± 4.9% at 7 years. Estimated freedom from type Ia endoleaks at 7 years was 91.8% ± 3.9%. A total of 21 late reinterventions were performed in 17 patients (33%). Most of them were performed to treat type II endoleaks with sac growth (47.6%; n = 10) and type Ib endoleak (23.8%; n = 5). Estimated freedom from reintervention at 7 years was 56.3% ± 7.9%. Estimated freedom from target vessel instability at 7 years was 91.5% ± 4.1%.

CONCLUSIONS

The 7-year results of chimney endovascular aortic repair procedures performed in our center confirm the long-term safety and effectiveness of this technique in a series of high-risk patients with large aneurysms. The present study has, to the best of our knowledge, the longest follow-up for patients treated with chimney endovascular aortic repair, and it provides data to the scarce literature on the long-term outcomes of this procedure, showing acceptable to good long-term results.

Results of the Chimney Technique in a Community Hospital

BACKGROUND

The chimney technique, fenestrated or branched endovascular aortic repair are endovascular options in patients with a juxtarenal, suprarenal or type IV thoraco-abdominal aneurysm. The chimney technique has specific advantages and disadvantages. A retrospective single center study was performed to describe the results.

PATIENTS AND METHODS

All consecutive patients in whom the chimney technique was used between 1th January 2011 and 31th December 2020 were included. We excluded patients who needed a revision of an existing EVAR and patients with a para-anastomotic aneurysm. Outcomes were reported in accordance with the reporting standards.

RESULTS

38 Patients were included in the study, a total of 59 chimney grafts were deployed. At a median follow-up duration of 26.6 months, there were 9 patients with occlusion of the chimney graft. In 1 patient an iliac renal bypass was performed. In the other patients the renal function stabilized and no further therapy was necessary. All chimneys in the mesenteric arteries remained patent. Gutter endoleak was seen in 5 patients, 3 patients were successfully treated and in the other 2 patients the gutter endoleak disappeared spontaneously.

CONCLUSIONS

Conclusions should be drawn carefully as this is a retrospective non-comparative study. Results from 38 patients treated with the chimney technique are presented. Chimney graft occlusion rate was 15.3% at the end of follow-up. However, the majority (77.8%) of the occluded stents were self-expandable stents, stressing the importance of selecting the right devices.

What we have learned from in-vitro studies of the chimney endovascular technique for treatment of complex abdominal aortic aneurysms: A systematic review

BACKGROUND

A considerable number of patients with abdominal aortic aneurysms (AAA) is not eligible for standard endovascular repair. These complex cases require alternative surgical approaches including the readily available chimney graft endovascular aneurysm repair (Ch-EVAR) or sealing (Ch-EVAS). The optimal configuration for Ch-EVAR or Ch-EVAS is important for success but not yet known.

OBJECTIVE

The aim of the present study was to analyze current data of the outcomes of in-vitro chimney graft treatment in complex AAA.

METHODS

A systematic review following PRISMA guidelines was conducted including studies reporting on gutter size, main graft compression, and chimney graft compression in in-vitro configurations.

RESULTS

The search resulted in 285 articles. 11 studies considering 219 individual tests could be included. Gutter size was comparable between Ch-EVAR and Ch-EVAS configurations. In Ch-EVAR set-ups, the deployed BECG were Advanta V12, VIABAHN®, and BeGraft. One type of SECG was used: VIABAHN®. The four types of main grafts (MG) deployed were: Endurant™ I/II; EXCLUDER Conformable AAA Endoprosthesis and AAA Endoprosthesis, and AFX™ Endovascular AAA Delivery System. In the EVAS-configurations, the Nellix® EVAS system was deployed. In general, SECG presented smaller gutters with higher chimney graft compression. 30% main grafts oversizing seems to give the smallest gutters without high risk of infolding of MG. Oversizing, EndoAnchors, and secondary endobag filling (in Ch-EVAS) reduced gutter sizes. CG ballooning during the entire polymer injection in Ch-EVAS prevented CG compression.

CONCLUSION

In-vitro investigations provide insight in optimal Ch-EVAR and Ch-EVAS configurations for simulated complex AAA repair. The findings above might aid physicians in their planning to potential CG set-ups and can be used in future research to refine the most optimal configuration for chimney graft technique in complex AAA.

In Vitro Radiological Evaluation of Different Types of Chimney Stents Using a Silicon Flow Model with Adjustable Physiological Simulating Conditions

OBJECTIVE

To evaluate in vitro the performance of in vivo published covered or bare metal chimney stents (ChSs) in combination with the Endurant II abdominal endograft (Medtronic) as the only CE approved main graft (MG) in the treatment of juxtarenal abdominal aortic aneurysms with the chimney endovascular aneurysm repair (chEVAR) technique.

METHODS

Bench top experimental study. A silicon flow model with adjustable physiological simulating conditions and patient based anatomy was used to test nine different MG-ChS combinations: Advanta V12 (Getinge); BeGraft+ (Bentley); VBX (Gore & Associates Inc.); LifeStream (Bard Medical); Dynamic (Biotronik); Absolute Pro (Abbott); double Absolute Pro; Viabahn (Gore) lined with Dynamic; and Viabahn lined with EverFlex (Medtronic). Angiotomography was performed after each implantation. DICOM data were analysed blindly twice per observer by three independent experienced observers. Each blinded evaluation was performed at one month intervals. The main analysed parameters were the area of gutters, MG and ChS maximum compression, and the presence of infolding.

RESULTS

Bland-Altman analysis confirmed adequate results correlation (p < .05). Each employed ChS showed significantly different performance favouring the balloon expandable covered stent (BECS). The smallest gutter area was seen in the combination with Advanta V12 (0.26 cm2). MG infolding was observed in all tests. The lowest ChS compression was observed in the combination with BeGraft+ (compression 4.91%, D ratio 0.95). In our model, BECSs showed higher angulations than bare metal stents (BMSs) (p < .001).

CONCLUSION

This in vitro study shows the variability of performance with each theoretically possible ChS and explains the divergent ChS outcomes in the published literature. BECS in combination with the Endurant abdominal device confirms their superiority vs. BMS. The presence of MG infolding in each test underlines the need for prolonged kissing ballooning. Angulation evaluation and comparison with other in vitro and in vivo publications demands the need for further investigation in transversely or upwardly oriented target vessels.

Systematic Review of the Current In Vitro Experience of the Endovascular Treatment of Juxtarenal Abdominal Aortic Aneurysms by Fenestrated and Parallel Endografting

OBJECTIVE

To identify and analyze the published in vitro benchtop experiments for the assessment of endovascular techniques used for the treatment of juxtarenal abdominal aortic aneurysms (jAAAs).

DATA SOURCES

Scopus, PubMed, and Web of Science.

REVIEW METHODS

A systematic literature search was carried out throughout March 2021 following PRISMA guidelines. Two investigators independently performed title and abstract screening to reveal all benchtop testing evaluating the endovascular treatment of jAAA.

RESULTS

A total of 19 studies were included, 8 evaluating fenestrated (FEVAR) and 11 parallel grafts (PGs). FEVAR studies used different custom testing apparatus (n=7) or 3D-printed models (n=1) to analyze dislodgement and migration resistance, misalignment consequences and causation, and bridging stents' radial force, flareability, fatigue, and fracture resistance. All PG studies used silicone-based models to analyze optimal oversizing, sealing length, gutter behavior, and possible reduction. Test evaluation in FEVAR in vitro testing was based on pullout force analysis (N=5), photo evaluation (n=1), fluoroscopy (n=1), X-rays (n=4), CT analysis (n=3), macro- and microscopic evaluation (n=4), water permeability (n=1), and fatigue simulator testing (n=1), while it was based on CT analysis in all PG studies adding ECG-gate in one study. The most frequently tested devices were Zenit (Cook) (n=7), Endurant (Medtronic) (n=5), and Excluder (Gore) (n=5) as main grafts, and Advanta V12 (n=14) as the bridging device.

CONCLUSIONS

This systematic review presents a broad analysis of the current in vitro methods evaluating the endovascular treatment of jAAA. Fundamental issues have been benchtop tested in both FEVAR and PGs. The analysis of the included studies allowed to recommend an optimal testing design. In vitro testing is a potential tool to further elucidate points of attention hard to investigate in vivo to finally enhance the endovascular treatment outcomes. Future in vitro studies are needed to evaluate the in vitro performance of all indistinctively used devices in the clinical practice.

Endovascular treatment of a tuberculous aneurysm of the pararenal abdominal aorta leading to an aortoduodenal fistula

This case report describes the presentation of a 79-year-old woman with no significant past medical history diagnosed with a saccular aneurysm with an aortoduodenal fistula. An emergency endovascular aneurysm repair was performed. Although the postoperative course was uneventful, 10 months after endovascular aneurysm repair, the patient died of miliary tuberculosis from mycotic aneurysms. Mycotic aneurysms are uncommon, and mycotic aneurysms caused by Mycobacterium tuberculosis are even rarer. Therefore, we believe our study makes a significant contribution to the literature given the rarity of the condition and suggests the importance of maintaining a high index of suspicion for tuberculosis as a possible cause of aortoduodenal fistula in primary mycotic aneurysm.

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.

Thoracic aortic parallel stent-graft behaviour when subjected to radial loading

To manage complex aortic arch disease using minimally invasive techniques, interventionalists have reported the use of multiple stent-graft devices deployed in a parallel configuration. The structural device-device and device-artery interactions arising during aortic arch parallel endografting, also known as chimney thoracic endovascular aortic repair (ch-TEVAR), is not well understood. Through the use of a radial force testing system we sought to characterise both the loading and deformation behaviour of parallel endografts in representative ch-TEVAR configurations. Four commercially available devices (Bentley BeGraft, Gore TAG, Gore Viabahn, and Medtronic Valiant) were subjected to uniform radial load individually, and in six combinations, to quantify loading profiles. Image data collected during testing were analysed to evaluate mechanical deformations in terms of gutters, chimney and main endograft compression, as well as graft infolding. Parallel endografting was found to increase radial loads when compared to standard TEVAR. Chronic outward force during ch-TEVAR was dependent on main endograft manufacturer, with TAG combinations leading to consistently higher loads than Valiant, but independent of chimney graft type. Endograft deformations were dependent on chimney graft type, with Viabahn combinations presenting with lower gutter areas and increased lumen compression than BeGraft. Chimney graft deformations were also influenced by deployment arrangement in the case of double ch-TEVAR. This study emphasizes the significant variability in both radial loads and mechanical deformations between clinically relevant ch-TEVAR configurations.

Hybrid Repair With Endovascular Debranching of the Aberrant Right Subclavian Artery for Complicated Type B Aortic Dissection in Patients With Kommerell's Diverticulum

PURPOSE

Aberrant right subclavian artery (ARSA) associated with Kommerell's diverticulum (KD) is a common congenital arch anomaly. It can be complicated by type B aortic dissection (TBAD) or aneurysmal formation at its ostium. Recently, hybrid repair with thoracic endovascular aortic repair (TEVAR) has appeared to be more favorable. Due to the normal anatomic proximity of the ARSA to the left subclavian artery (LSA) orifice in KD, coverage of the bilateral subclavian arteries (SCAs) to obtain an adequate proximal landing zone (PLZ) is usually required, and double cervicotomy for SCA revascularization potentially increases the risk of complications.

TECHNIQUE

This technique was demonstrated on a 50-year-old man presenting with progressive aneurysmal formation of KD with ARSA after chronic TBAD. A 3-step technique, namely left cervical debranching with a left common carotid artery to LSA bypass graft, TEVAR, and an LSA-to-ARSA endovascular debranching with a self-expanding covered stent by a through-and-through wire from the right brachial artery to the bypass graft, was performed in a 1-stage repair to cover the primary tear of TBAD and preserve the bilateral SCAs. The postoperative course was uneventful.

CONCLUSION

This technique can prevent complications from double cervicotomy and achieve an adequate PLZ with preservation of the bilateral SCAs for TEVAR.

The PROTAGORAS 2.0 Study to Identify Sizing and Planning Predictors for Optimal Outcomes in Abdominal Chimney Endovascular Procedures

OBJECTIVE

The aim was to identify predictors of adequate pre-operative sizing and planning for chimney endovascular aortic repair (ChEVAR) in order to reduce the incidence of persistent type Ia endoleaks (IaELs) without influencing chimney graft (CG) patency.

METHODS

Consecutive patients who underwent ChEVAR between January 2009 and December 2017 at a single centre were evaluated retrospectively. Included were patients treated with one device combination (Medtronic Endurant mated with Getinge Advanta V12/iCast) and placement of single or double CG. The freedom from IaEL related re-interventions and primary CG patency was estimated by measuring aortic stent graft oversizing (OS), total neck length (TNL), and a composite parameter (L-OS: TNL [mm] + OS [%]).

RESULTS

Seventy-three patients who underwent placement of 101 CGs (45 single, 28 double) met the inclusion criteria. The median radiological follow up was 25.5 (interquartile range [IQR] 12-48) months. Freedom from IaEL related re-intervention was achieved in 94.6% with a median OS of 38.5% (IQR 30%-44%, p = .004), TNL 19 mm (16-25 mm, p = .62), and L-OS 59 (51-65, p = .018). Primary CG patency was achieved in 95% of the cases with a median OS of 36% (29%-42%, p = .008), TNL 19 mm (15.5-26 mm, p = .91), and L-OS 57 (50-64, p = .005). By using the receiver operating characteristic curve, an optimal cut off to prevent IaEL related re-interventions was identified by an OS of 30% (p < .001; L-OS 55, p = .006) and to avoid CG stenosis/occlusions by OS 42% (p < .001; L-OS 65, p < .001). In multivariable analysis, aortic endograft OS was the only independent parameter preventive for IaEL related re-intervention (odds ratio, 0.78; 95% confidence interval, 0.61-0.99).

CONCLUSION

With the Endurant-Advanta V12/iCast combination, an aortic stent graft OS of at least 30% (range 30%-42%) should be used to avoid type Ia endoleaks and likewise to ensure CG patency.

Parallel Grafting Should Be Considered as a Viable Alternative to Open Repair in High-Risk Patients With Paravisceral Aortic Aneurysms

BACKGROUND

Parallel grafting presents a viable method for treating patients with complex aortic aneurysms. The current literature is limited to mostly pararenal configurations. We examined our results in patients with SMA and/or Celiac artery involvement.

METHODS

A retrospective analysis was performed for all patients undergoing parallel grafting during the period of 2014 to 2018 at a single institution. All patients had at least SMA with and/or without Celiac artery parallel grafting.

RESULTS

Seventy-nine patients (65% male, median age 74) were treated with 208 parallel grafts. Median ASA score is 4. Forty-nine cases were elective, 22 urgent, and 8 emergent. Mean pre-operative aneurysm diameter was 7.1 cm (4.6-15 cm). Self-expanding covered stents were used for the renal arteries (mean 6.3mm), and balloon-expandable covered stents were used for the SMA and Celiac (mean SMA 8.6 mm, mean celiac 8.3 mm). Axillary exposure was the choice of access in 68 patients (86%). Technical success was achieved in all cases. We defined this as aneurysm sac exclusion with patent visceral stent grafts, and absent to mild gutter leaks. Mean aortic graft proximal seal achieved was 48mm. Coverage extended above the celiac artery in 75% (10% stented and 65% covered). Median contrast volume was 145ml, operative duration was 4 hours, fluoroscopy time was 56 min, and EBL was 250 ml. Perioperative mortality was 6.1%. 4.5%, and 25%, for the elective, urgent, and emergent groups, respectively. There was no incidence of spinal cord ischemia. Axillary access was complicated in 4 patients, requiring patch closure of the axillary artery. One patient developed postprocedural ESRD from a rupture and ATN despite patent renal stents. Of those patients with a patent GDA and celiac coverage, 2 required a cholecystectomy. Nine patients had a persistent gutter leak at the conclusion of the procedure. Median follow-up was 12 months. On follow-up imaging, all SMA and Celiac stents were patent. Six renal stents were occluded and 2 patients progressed to ESRD, both solitary renal periscope configurations at the index procedure. Only 4 patients had persistent gutter leaks with 2 requiring reintervention. Ninety-five percent of patients demonstrated sac regression or stabilization with a mean sac size of 6.5 cm.

CONCLUSIONS

Parallel grafting presents a safe, efficacious and off the shelf alternative to conventional repair of complex aortic aneurysms involving the visceral aorta.

Long-term chimney/snorkel endovascular aortic aneurysm repair experience for complex abdominal aortic pathologies within the PERICLES registry

OBJECTIVE

The early and short-term efficacy of the snorkel/chimney technique for endovascular aortic aneurysm repair (ch-EVAR) have been previously reported. However, long-term ch-EVAR performance, vessel patency, and patient survival remain unknown. Our study evaluated the late outcomes to identify possible predictors of failure within the PERICLES (performance of the chimney technique for the treatment of complex aortic pathologies) registry.

METHODS

Clinical and radiographic data from patients who had undergone ch-EVAR from 2008 to 2014 in the PERICLES registry were updated with an extension of the follow-up. Regression models were used to evaluate the relevant anatomic and operative characteristics as factors influencing the late results. We focused on patients with ≥30 months of follow-up (mean, 46.6 months; range, 30-120 months).

RESULTS

A total of 517 patients from the initial PERICLES registry were included in the present analysis, from which the mean follow-up was updated from 17.1 months to 28.2 months (range, 1-120 months). All-cause mortality at the latest follow-up was 25.5% (n = 132), with an estimated patient survival of 87.6%, 74.4%, and 66.1% at 1, 3, and 5 years, respectively. A subgroup of 244 patients with 387 chimney grafts placed (335 renal arteries, 42 superior mesenteric arteries, 10 celiac arteries) and follow-up for ≥30 months was used to analyze specific anatomic and device predictors of adverse events. In the subgroup, the technical success was 88.9%, and the primary patency was 94%, 92.8%, 92%, and 90.5% at 2.5, 3, 4, and 5 years, respectively. The mean aneurysm sac regression was 7.8 ± 11.4 mm (P < .0001). Chimney graft occlusion had occurred in 24 target vessels (6.2%). Late open conversion was required in 5 patients for endograft infection in 2, persistent type Ia endoleak in 2, and endotension in 1 patient. The absence of an infrarenal neck (odds ratio, 2.86; 95% confidence interval, 1.32-6.19; P = .007) was significantly associated with long-term device-related complications. A sealing zone diameter >30 mm was significantly associated with persistent or late type Ia endoleak (odds ratio, 4.86; 95% confidence interval, 1.42-16.59; P = .012).

CONCLUSIONS

The present analysis of the PERICLES registry has provided the missing long-term experience for the ch-EVAR technique, showing favorable results with more than one half of the patients surviving for >5 years and a chimney graft branch vessel patency of 92%. The absence of an infrarenal neck and treatment with a sealing zone diameter >30 mm were the main anatomic long-term limits of the technique, requiring adequate preoperative planning and determination of the appropriate indication.

Treatment Results of Endovascular Aneurysm Repair Using the Parallel Stent-Graft Double D Technique for Distal Saccular Abdominal Aortic Aneurysms and Common Iliac Aneurysms

BACKGROUND

Endovascular aneurysm repair (EVAR) using a bifurcated stent graft may involve technical challenges when aortic disease (aneurysm or dissection) consists of a length <70 mm between the inferior renal artery and aortic bifurcation or narrow aortic bifurcation that is common in asymmetric distal abdominal aortic aneurysms (AAAs) or iliac artery aneurysms (IAAs). We use EVAR with the double D technique (DDT-EVAR) for such cases, which involves straight type of stent grafts with same diameter in left and right that are deployed parallel to an aortic cuff that has been previously placed. In addition, DDT-EVAR can preserve the inferior mesenteric artery (IMA) for IAA.

METHODS

DDT-EVAR was performed for 21 of 910 (2%) cases from April 2007 to April 2019 at our institution. The median patient age was 74 years (range, 52-85). Nineteen patients (90%) were men. Six patients (all saccular; 1 rupture) had AAAs, 12 had IAAs, and 3 had chronic type B aortic dissociation (TBAD) for re-entry closure. AAA and IAA had diameters of 45 mm (range, 34-71) and 34 mm (range, 25-58), respectively. An aortic cuff was used for 19 (90%) cases. Endurant II (Medtronic, Santa Rosa, CA) was used for 12 cases. The Excluder (W.L. Gore & Associates, Inc, Flagstaff, AZ) was used for 7 cases. Endurant II was used for 20 cases, and the VBX (W.L. Gore & Associates, Inc) was used for 1 case as stent-graft limbs.

RESULTS

The procedural success rate was 100%. The median operative time was 146 min (range, 88-324). IMA planned for preservation was successful for all 12 cases. Type I and type III endoleaks were not observed. With TBAD, flow to the false lumen decreased or disappeared, and no complications during the hospital stay were associated with the procedure. For 2 patients whose procedure involved Endurant II stent-graft limb, limb occlusions were observed postoperatively, and reintervention was required. No other patients required additional treatment at a median follow-up of 18 months (range, 4-50).

CONCLUSIONS

DDT-EVAR is a safe and straightforward technique for the treatment of distal AAA, common iliac artery aneurysm, and TBAD. It may help preserve the IMA and internal iliac artery, even when it is impossible to preserve them with a bifurcated stent graft.

Gutter Characteristics and Stent Compression of Self-Expanding vs Balloon-Expandable Chimney Grafts in Juxtarenal Aneurysm Models

Purpose: To assess in silicone juxtarenal aneurysm models the gutter characteristics and compression of different types of chimney graft (CG) configurations. Materials and Methods: Fifty-seven combinations of Excluder C3 or Conformable Excluder stent-grafts (23, 26, and 28.5 mm) were deployed in 2 silicone juxtarenal aneurysm models with 3 types of CGs: Viabahn self-expanding (VSE; 6 and 13 mm) or Viabahn balloon-expandable (VBX; 6, 10, and 12 mm) stent-grafts and Advanta V12 balloon-expandable stent-grafts (ABX; 6 and 12 mm). Setups were divided into 4 groups on the basis of increasing CG and main graft (MG) diameters. Two independent observers assessed gutter size and type as well as CG compression on computed tomography scans using postprocessing software. Results: In the smaller diameter combinations (6-mm CG and 23-, 26-, and 28.5-mm MGs), both VSE (p=0.006 to 0.050) and ABX (p=0.045 to 0.050) showed lower gutter areas and volumes compared with VBX. In turn, the VBX showed a nonsignificant tendency to decreased compression, especially compared to ABX. Use of the Excluder C3 showed a 6-fold increase in type A1 gutters (related to type Ia endoleak) as compared to the Conformable Excluder (p=0.018). Balloon-expandable stent-grafts (both ABX and VBX) showed a 3-fold increase in type A1 gutters in comparison with self-expanding stent-grafts (p=0.008). Conclusion: The current study suggests that use of the Conformable Excluder in combination with VSE chimney grafts is superior to the other tested CG/MG combinations in terms of gutter size, gutter type, and CG compression.

FEVAR/BEVAR have limitations and do not always represent the preferred option for juxtarenal reconstruction

Following the definition given by the recent ESVS guidelines, juxtarenal abdominal aortic aneurysm (JAAA) is defined as an aneurysm extending up to but not involving the renal arteries, necessitating suprarenal aortic clamping for open surgery, i.e. a short neck (<10 mm). JAAA repair always represents a challenge intervention, either by open or endovascular means, mostly related to the renal arteries involvement. Concerning endovascular repair, different options can be considered. Among them, fenestrated endografts (FEVAR) should be considered as a first option1, due to their reported safety and efficacy. However, when the anatomy is not favorable or when FEVAR devices are not available in an emergency setting for instance, other alternatives can be considered like parallel graft or chimney technique (ChEVAR). Do nothing is the last alternative when medical and anatomical circumstances are absolutely poor. In the following pages, we will review the limitations of FEVAR and branched endografts, the better indications and anatomical conditions for a successful repair with ChEVAR technique and its current clinical results reported in the literature.

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.

In Vitro Evaluation of Balloon-Expandable Chimney Grafts in the Renal Arteries Combined With the Endurant Endograft

Purpose: To compare balloon-expandable covered stents (BECS) available for use as renal chimney grafts to the Advanta V12 approved for use with the Endurant endograft. Materials and Methods: A silicone model was manufactured based on preoperative computed tomography angiography (CTA) scans of a patient with a 7-cm juxtarenal aneurysm treated with an Endurant bifurcated endograft and an Advanta V12 covered stent for the 6-mm-diameter right renal artery. The model was placed in a flow box filled with a 37°C blood-mimicking solution equipped with a pulsatile pumping system (140/60 mm Hg). The tested BECS were the Advanta V12, the VBX, and the BeGraft+. A 36-mm-diameter Endurant II endograft with a 16-mm-diameter contralateral limb and a 6×59-mm BECS chimney graft were used in 9 consecutive tests (3 for each combination). After each implantation, the model was placed in the CT scanner, and 2 radiologists blinded to the test device independently measured the gutter areas and the patent chimney graft lumen at the level of the Endurant’s suprarenal stent, at the level of the chimney’s maximum curvature, and 10 mm inside the renal artery. The intraclass correlation coefficients (ICC) were calculated to assess interreader reliability. Results: The mean gutter areas were 19.3±7, 20.2±8, and 22.3±8 mm2 for the Advanta, VBX, and BeGraft+, respectively (all p>0.05). At the level of the aortic endograft’s suprarenal stent struts, the mean diameter of the Advanta V12, VBX, and BeGraft+ were 4.46±0.3, 4.12±0.4, and 4.12±0.3 mm, respectively (all p>0.05). At the level of the maximum chimney graft angulation, the mean diameters were 3.77±0.3, 4.16±0.1, and 3.74±0.3 mm, respectively (all p>0.05). In the right renal artery, the mean diameters were 3.91±0.2, 4.05±0.9, and 4.3±0.4 mm, respectively (all p>0.05). The ICCs varied between 0.7 and 0.9, indicating good agreement between readers. Conclusion: These in vitro findings showed comparable results between the Advanta V12 and the available BECS used in conjunction with the Endurant endograft according to the instructions for use. Further clinical evaluation is needed to confirm these results.

Optimization schemes for endovascular repair with parallel technique based on hemodynamic analyses

Endovascular repair with parallel stent-grafts (SG) is a challenging technique that reconstructs the luminal flow pathways by implanting parallel-placed SGs into the vessel. After treatment, occlusion and shifting of the parallel SGs are sometimes reported, which could be fatal and difficult to be re-operated. These issues are highly related to the local hemodynamic conditions in the stented region. In this study, a patient case treated by the octopus endograft technique (a head-SG with three limb-SGs) and experienced limb-SG occlusion is studied. 3-D models are established based on computed tomography (CT) angiography datasets pretreatment and posttreatment as well as during follow-ups. Hemodynamic quantities such as pressure drop, wall shear stress-related parameters, and flow division in limb-SGs and visceral arteries are quantitatively investigated. Optimizations on the length of the head-SG and diameter of the limb-SGs are analyzed based on various scenarios. The results indicate that when reconstructing the flow pathways via octopus stenting, it is important to ensure the flow distribution as physiologically required with this new morphology. Position (or length) of the head-SG and diameter of the limb-SGs play an important role in controlling flow division, and high time average wall shear stress (TAWSS) around the head-SG acts as a main factor for graft immigration. This study, by proposing optimization suggestions with hemodynamic analyses for a specific case, implicates that pretreatment SG scenarios may assist in wise selection and placement of the device and thus may improve long-term effectiveness of this kind of challenging endovascular repair techniques.

Successful Management of a Type B Gutter Related Endoleak after Chimney EVAR by Coil Assisted Onyx Embolisation

Introduction

The aim was to describe possible management of a persistent gutter related type Ia endoleak after treatment of a symptomatic pararenal aortic aneurysm with the chimney endovascular technique.

Report

A 77 year old man with a symptomatic 6 cm pararenal aortic aneurysm was referred. Computed tomography angiography (CTA) showed a pararenal aortic aneurysm with involvement of both renal arteries and extension up to the superior mesenteric artery. The patient underwent treatment by placement of triple chimney grafts and an abdominal stent graft. Completion angiography showed a gutter related type Ia endoleak. As the type Ia endoleak persisted at the three month CTA follow up and according to the PERICLES registry classification of endoleaks, a type B causative mechanism was detected. Embolization of the gutters was performed with coils and onyx, leading to complete resolution of the gutters on completion angiography. The 10 month post-operative magnetic resonance angiogram showed no further evidence of any endoleak and complete exclusion of the aneurysm.

Conclusion

Treatment of persistent type B gutter related endoleaks after triple chimney endovascular aneurysm repair can be performed with the placement of coils and adjunctive use of fluid agents.

Midterm Results with the Open Chimney Technique during Endovascular Aneurysm Repair

PURPOSE

To report the midterm experience with chimney-endovascular aneurysm repair (Ch-EVAR) with the use of open self-expending stents for branch vessel preservation.

MATERIALS AND METHODS

From July 2010 to May 2017, 67 patients underwent open Ch-EVAR because their proximal landing zones were adjacent to, or covered, the renal or mesenteric arteries (Zones 7-9), and they were not suitable for standard or fenestrated endovascular aneurysm repair. The proximal landing zone was relocated below the highest renal artery in 46 cases, the superior mesenteric artery in 17 cases, and the celiac artery in 4 cases, using 84 open chimneys (131 stents). A subgroup analysis was performed between an early (2010-2014) and a later (2015-2017) time period. Thirty-two patients were treated during the early period, and 35 were treated during the later period. In the later period, open chimneys were strengthened by a second self-expanding stent.

RESULTS

The primary technical success rate was 89.6%; the early mortality rate was 9.0%; and the median follow-up duration was 13 months (range, 1-76 months). The estimated actuarial survival rate was 85.7% in year 1 and 79.2% in year 2, and the estimated patency rate of open chimneys reached 95.2% at 2 years. Aneurysm sac regression >5 mm and sac stability rates were 39.0% and 57.6%, respectively. Freedom from aneurysm-related reintervention was lower in the later period (log-rank P = .04), while type Ia endoleaks tended to be twice as likely.

CONCLUSIONS

Midterm results of open Ch-EVAR show high technical success with acceptable midterm patency and lack of endoleak in appropriately selected patients. The advantages over covered stents are lower-profile delivery systems and maintenance of branch vessel patency in early bifurcations and overlying visceral vessels.

Deployment of stent graft in an excessively higher position above the renal artery induces a flow channel to the aneurysm in chimney endovascular aortic aneurysm repair: an in vitro study

We aimed to investigate the influences of the sealing length above the renal artery (RA) on gutter formation, non-apposed regions between the aortic wall, stent graft (SG), and chimney graft and incidence of flow channel to the aneurysm in chimney endovascular aortic aneurysm repair (Ch-EVAR) using a juxtarenal abdominal aortic aneurysm model. Neck diameter and length of the silicone model were 24 and 4 mm, respectively. In double Ch-EVAR configuration using Advanta V12, 12 combinations were tested three times with two sizes [28.5 (20%-oversize) and 31 (30%-oversize) mm] of Excluder SG, three sealing lengths above the RA (10, 20, and 30 mm), and two deployment positions (anatomical and cross-leg). Gutter area, non-apposed region, and flow channels to the aneurysm were analyzed using micro-computed tomography. Average gutter area and non-apposed region of 30%-oversize SG were significantly smaller than those of 20%-oversize SG (p = 0.05). Furthermore, the non-apposed region of 30%-oversize SG with a 30-mm sealing length was significantly larger than that of the other sealing lengths. For 20%-oversize SGs, flow channel to the aneurysm was observed, except for the anatomical deployment with the sealing length of 10 mm. For 30%-oversize SGs, flow channel was absent, except for the SG with a 30-mm sealing length in both deployment positions. These flow channels were frequently formed through a valley space, existing in the lower unibody above the two limbs. Our data indicated that the optimal sealing length should be chosen in consideration of the device design difference due to the device diameter in Ch-EVAR.

Chimney parallel grafts and thoracic endovascular aortic repair for blunt traumatic thoracic aortic injuries: A systematic review

BACKGROUND

Whilst the management of blunt traumatic thoracic aortic injury has seen a paradigm shift to an 'endovascular first' approach, the limitations of thoracic endovascular aortic repair remain. An inadequate proximal landing zone limits the use of thoracic aortic stent grafts and in an emergent polytrauma setting, aortic arch debranching via open surgery may not be practical or feasible. A wholly endovascular approach to debranching utilising 'off-the-shelf' stents and parallel graft techniques may represent a possible solution. Hence, we sought to perform a systematic review investigating the use of chimney graft techniques alongside thoracic aortic stenting in blunt traumatic thoracic aortic injury.

METHODS

We performed the systematic review in accordance to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. Searches were performed on Medline (PubMed), Web of Science and Scopus to identify articles describing the use of chimney grafts in traumatic aortic transection (PROSPERO: CRD42017082549).

RESULTS

The systematic search revealed 172 papers, of which 88 duplicates were removed resulting in 84 papers to screen. Based on title, abstract and full text review, six articles were included for final analysis. There were nine patients in total with an average age of 41 (three females, five males, one unspecified), all with significant polytrauma, secondary to the mechanism of injury. A variety of stents were used between centres, with techniques showing a predominance to stenting of the left subclavian artery (77%, n = 7). The technical success rate was 82%, with two (18%) cases of type 1 endoleaks, of which one resolved spontaneously.

CONCLUSIONS

Despite the encouraging results, this by no means provides for a firm conclusion given the small sample size. Patients should still be judiciously selected on a case-by-case basis when employing the chimney graft technique. Larger cohort studies are needed to establish these findings.

Comparison of Two Different Techniques for Isolated Left Subclavian Artery Revascularization During Thoracic Endovascular Aortic Repair in Zone 2

Purpose: To analyze the results of isolated left subclavian artery (LSA) revascularization during thoracic endovascular aortic repair (TEVAR) using carotid-subclavian bypass (CSbp) or chimney grafts (CGs). Methods: A retrospective multicenter, observational study identified 73 patients (mean age 68±13 years, range 22–87; 56 men) with acute or chronic thoracic aortic lesions who underwent TEVAR with isolated LSA revascularization using either CSbp (n=42) or CGs (n=31) from January 2010 and February 2017. Primary endpoints were TEVAR-related mortality, postoperative stroke, freedom from type Ia endoleak, and LSA patency. Results: Primary technical success was achieved in all cases. Early TEVAR-related mortality was 4.2% (CSbp 2% vs CG 6%, p=0.571). Two (3%) patients had major ischemic strokes (one in each group). Mean follow-up was 24±21 months (range 1–72; median 15). Estimated freedom from TEVAR-related mortality was 93%±3% (95% CI 84.3% to 97.0%) at 12 and 36 months, with no significant difference between CSbp and CG (p=0.258). Aortic reintervention did not differ between the groups (CSbp 5% vs CG 6%, p=0.356); nor did freedom from type Ia endoleak (CSbp 98% vs CG 87%, p=0.134). Gutter-related endoleaks occurred in 4 (13%) CG patients, but none of the patients experienced sac enlargement or the need for reintervention and none died. Primary patency of the LSA was 100% for the entire group during the observation period. Conclusion: In our experience, LSA revascularization proved most satisfactory and equally effective with both the CSbp and CG techniques, without discernible differences at midterm follow-up.

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.

Parallel stent grafts for the treatment of complex aortic aneurysms: A single center study

Background

“Chimney” techniques with parallel grafts used in order to extend the landing zones in endovascular aneurysm repair (ch-EVAR) are increasingly being reported. Conflicting data has been reported regarding the success and durability of the repair. We report a single center experience using ch-EVAR in treating complex aortic pathologies.

Methods

We performed a retrospective review of all patients treated with ch-EVAR in our institution between 2013 and 2017. Data collected included patients demographics, indications for surgery, configuration of parallel grafts, technical success, and perioperative morbidity and mortality. Follow-up data included aortic sac size, reintervention rate, and overall mortality.

Results

Thirty-five patients underwent treatment of their aneurysms with parallel grafts. Sixty parallel grafts were placed. Mean age was 75 years (range 59–93) and 30 (85%) were male. Technical success was achieved in 32 (91%) patients. Mean follow up was 12 months. Sac size decreased in diameter or remained unchanged in 26 of the 30 (86.6%) patients. Four patients were found to have enlarging aneurysms due to gutter endoleaks. All were treated successfully with endovascular methods. The estimated primary patency was 95% at 12 months. Probability of freedom from intervention was 75% at 12 months. No late aneurysm related mortality occurred.

Conclusion

The use of ch-EVAR in treating complex aortic aneurysms is technically feasible and safe. Gutter endoleaks are encountered only in a minority of the cases, and can be treated with minimally invasive techniques. Longer term follow up is required to evaluate the patency of these parallel grafts and the durability of the aneurysm exclusion.

Long Parallel Stent Grafts for the Treatment of Complex Aortic Aneurysms

PURPOSE

To describe our experience with the chimney technique in endovascular aneurysm repair (ch-EVAR) using long parallel grafts (PGs) of 100 mm or more for the treatment of complex aortic aneurysms.

MATERIALS AND METHODS

From 2009 to 2016, data were prospectively collected for patients who underwent ch-EVAR using long PGs. Data included patient demographics and aortic anatomy, technical success, patency and reintervention rate.

RESULTS

A total of 29 long PGs were placed in 18 patients (males 16, average age 71 years). Nine (50%) suffered from thoracoabdominal aortic aneurysms, 4 (22%) from juxtarenal aortic aneurysms and 3 (17%) from suprarenal aortic aneurysms and 2 (11%) were treated for abdominal aortic aneurysms that required revascularization of a pelvic kidney. Twenty (70%) of the PGs were 100 mm in length, and 9 (30%) were 150 mm. Long PGs were successfully placed in 16 (89%) patients. Two patients (11%) expired in the perioperative period. Mean period of follow-up was 12 months (range 1-43 months). Sac size decreased in size or remained unchanged in 13 patients (72%). Three patients with sac enlargement underwent successful endovascular treatment the type 1A gutter endoleaks. None required reintervention of the PGs. Three patients expired, none from aneurysm-related deaths.

CONCLUSION

The use of long PGs is a feasible technique and provides a durable repair of complex aortic aneurysms in midterm follow-up. Despite the length of the PGs, gutter endoleaks are encountered only in a minority of the cases and can be treated minimally invasive techniques.

Configuration affects parallel stent grafting results

OBJECTIVE

A number of adjunctive "off-the-shelf" procedures have been described to treat complex aortic diseases. Our goal was to evaluate parallel stent graft configurations and to determine an optimal formula for these procedures.

METHODS

This is a retrospective review of all patients at a single medical center treated with parallel stent grafts from January 2010 to September 2015. Outcomes were evaluated on the basis of parallel graft orientation, type, and main body device. Primary end points included parallel stent graft compromise and overall endovascular aneurysm repair (EVAR) compromise.

RESULTS

There were 78 patients treated with a total of 144 parallel stents for a variety of pathologic processes. There was a significant correlation between main body oversizing and snorkel compromise (P = .0195) and overall procedural complication (P = .0019) but not with endoleak rates. Patients were organized into the following oversizing groups for further analysis: 0% to 10%, 10% to 20%, and >20%. Those oversized into the 0% to 10% group had the highest rate of overall EVAR complication (73%; P = .0003). There were no significant correlations between any one particular configuration and overall procedural complication. There was also no significant correlation between total number of parallel stents employed and overall complication. Composite EVAR configuration had no significant correlation with individual snorkel compromise, endoleak, or overall EVAR or procedural complication. The configuration most prone to individual snorkel compromise and overall EVAR complication was a four-stent configuration with two stents in an antegrade position and two stents in a retrograde position (60% complication rate). The configuration most prone to endoleak was one or two stents in retrograde position (33% endoleak rate), followed by three stents in an all-antegrade position (25%). There was a significant correlation between individual stent configuration and stent compromise (P = .0385), with 31.25% of retrograde stents having any complication.

CONCLUSIONS

Parallel stent grafting offers an off-the-shelf option to treat a variety of aortic diseases. There is an increased risk of parallel stent and overall EVAR compromise with <10% main body oversizing. Thirty-day mortality is increased when more than one parallel stent is placed. Antegrade configurations are preferred to any retrograde configuration, with optimal oversizing >20%.

Intraoperative Gutter Leaks That Merit Our Attention

INTRODUCTION

The natural history and potential morbidity of gutter endoleaks are unclear. We present our experience with intraoperative gutter endoleaks and strategies to determine which of these require intervention.

METHODS

This is a retrospective review of all patients treated with parallel stent grafts from January 2010 to September 2015. We reviewed all operative records and intraoperative angiograms as well as all postoperative imaging and secondary interventions. All gutter leaks were classified as low-flow/nonsac-enhancing gutter endoleaks or high-flow/sac-enhancing gutter endoleaks. Adjunctive interventions to manage the gutter leaks were noted, as were all subsequent interventions for gutter leak and endoleak management.

RESULTS

Seventy-eight patients had 144 parallel stents placed over a 5-year period with an average of 1.8 stents per patient. Twenty-eight patients (36%) had gutter endoleaks diagnosed intraoperatively. Seventeen patients had adjunctive procedures to reduce gutter leaks prior to leaving the operating room (OR). Patients selected for treatment had gutters filling early during completion angiography and/or contrast enhancement of the aneurysm sac. Twenty-two patients (28%) left the OR with low-flow/delayed/nonsac-enhancing gutter endoleaks. At 30 days, a total of 6 persistent gutter endoleaks were diagnosed on computed tomographic angiography. This gives a 73% rate of resolution for low-flow/nonaneurysm sac-enhancing endoleaks. There were 2 de novo endoleaks not detected at the index procedure diagnosed at 6-month follow-up. Of the 8 total postoperative endoleaks, 5 required additional intervention with a 100% success rate. Multivariate analysis revealed that the only significant predictor of having a postoperative endoleak is leaving the OR with an endoleak.

CONCLUSIONS

Intraoperative treatment of gutter endoleaks has an acceptable rate of resolution. It does have a high rate of converting high-flow endoleaks to low-flow endoleaks. Low-flow/nonsac-enhancing gutter endoleaks have a high rate of spontaneous resolution. Intraoperative gutter endoleaks are not predictive of future aneurysm sac growth.

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.

Parallel-Stenting Technique in a Sandwich Configuration for Hypogastric Artery Preservation during Endovascular Aneurysm Repair: An In Vitro Study

BACKGROUND

The aim of the study was to identify the best conditions in iliac sandwich procedure for hypogastric artery preservation during endovascular aneurysm repair, testing different devices, different oversizing (OS) degrees as well as different methods to measure it.

METHODS

Four external iliac devices (16-mm Endurant and 12-mm Aorfix limb extensions; 11- and 13-mm Viabahn endografts) were tested with 2 distinct internal iliac stent grafts (8-mm Advanta V12 and 8-mm Viabahn) inside different proximal silicon iliac limb models (10, 12, 14, 16, and 18 mm), simulating an iliac sandwich procedure for hypogastric preservation. After remodeling all devices in a saline bath at 37°C, the combinations were computed tomography scanned. Gutter size, parallel-stent compression, and inadequate parallel-stent deployment or infolding were recorded. Oversizing between both parallel stents and the iliac limb models were examined in terms of added diameter, perimeter, and area being additionally compared.

RESULTS

All three sizing methods (diameter, perimeter, and area) were highly correlated (diameter OS to perimeter and area OS correlation coefficient 0.998 and 0.997, respectively, P < 0.001 for both); thus, diameter OS was used for further comparisons. Increasing diameter OS (< 30%, 30-55%, 55-75%, and > 75%) showed a significant tendency toward smaller gutters (38.9, 12.2, 5.4, and 2.6 mm², respectively, P < 0.001) but also increasing parallel-stent compression (13.5%, 28.9%, 43.9%, and 55.1%, P < 0.001) and infolding (0%, 0%, 38%, and 60%, P < 0.001). There were no significant differences between the analyzed devices.

CONCLUSIONS

In iliac sandwich procedures, better apposition is usually achieved when using 30-55% diameter OS; higher OS is related to smaller gutters but higher rates of malpositioning and parallel-stent compression. No clear recommendations in material selection can be performed. All sizing methods are highly correlated and predictable.

Natural history of gutter-related type Ia endoleaks after snorkel/chimney endovascular aneurysm repair

OBJECTIVE

Alternative endovascular strategies using parallel or snorkel/chimney (chimney endovascular aneurysm repair [ch-EVAR]) techniques have been developed to address the lack of widespread availability and manufacturing limitations with branched/fenestrated aortic devices for the treatment of complex abdominal aortic aneurysms. Despite high technical success and midterm patency of snorkel stent configurations, concerns remain regarding the perceived increased incidence of early gutter-related type Ia endoleaks. We aimed to evaluate the incidence and natural history of gutter-related type Ia endoleaks following ch-EVAR.

METHODS

Review of medical records and available imaging studies, including completion angiography and serial computed tomographic angiography, was performed for all patients undergoing ch-EVAR at our institution between September 2009 and January 2015. Only procedures involving ≥1 renal artery with or without visceral snorkel stents were included. Primary outcomes of the study were presence and persistence or resolution of early gutter-related type Ia endoleak. Secondary outcomes included aneurysm sac shrinkage and need for secondary intervention related to the presence of type Ia gutter endoleak.

RESULTS

Sixty patients (mean age, 75.8 ± 7.6 years; male, 70.0%) underwent ch-EVAR with a total of 111 snorkel stents (97 renal [33 bilateral renal], 12 superior mesenteric artery, 2 celiac). A mean of 1.9 ± 0.6 snorkel stents were placed per patient. Early gutter-related type Ia endoleaks were noted on 30.0% (n = 18) of initial postoperative imaging studies. Follow-up imaging revealed spontaneous resolution of these gutter endoleaks in 44.3%, 65.2%, and 88.4% of patients at 6, 12, and 18 months postprocedure, respectively. Long-term anticoagulation, degree of oversizing, stent type and diameter, and other clinical/anatomic variables were not significantly associated with presence of gutter endoleaks. Two patients (3.3%) required secondary intervention related to persistent gutter endoleak. At a mean radiologic follow-up of 20.9 months, no difference in mean aneurysm sac size change was observed between those with or without early type Ia gutter endoleak (-6.1 ± 10.0 mm vs -4.9 ± 11.5 mm; P = .23).

CONCLUSIONS

Gutter-related type Ia endoleaks represent a relatively frequent early occurrence after ch-EVAR, but appears to resolve spontaneously in the majority of cases during early to midterm follow-up. Given that few ch-EVAR patients require reintervention related to gutter endoleaks and the presence of such endoleak did not correlate to increased risk for aneurysm sac growth, its natural history may be more benign than originally expected.

Review of Treatment for Thoracoabdominal Aortic Aneurysm, and the Modern Experience of Multi-Branched Endograft in Taiwan

Thoracoabdominal aortic aneurysm (TAAA) is a complicated aortic disease. Most treatments for other aortic aneurysms have already shifted from conventional open surgery to endovascular operation; but for TAAA, open surgery remains the gold standard treatment. Several alternative treatments such as hybrid operation as well as endovascular techniques are utilized for the treatment of TAAA. Some of the procedures combine off-the-shelf devices such as the chimney procedure. Some other procedures required custom-made specialized stent grafts. A new off-the-shelf multi-branched endograft, T-branch graft, was released in late 2012, though it was not introduced into Taiwan until 2015. Ultimately, also we plan to report the experience of multi-branched endograft in Taiwan.

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.

The Sandwich Technique with Body Flossing Wire to Revascularize Left Subclavian Artery in Thoracic Endovascular Aortic Repair

BACKGROUND

To evaluate the safety and efficacy of the sandwich technique with the body flossing wire to revascularize the left subclavian artery (LSA) in thoracic endovascular aortic repair (TEVAR).

METHODS

From April 2014 to April 2015, 20 consecutive patients with a variety of thoracic aortic pathologies who underwent LSA revascularization with the sandwich technique and body flossing wire during TEVAR were included. Outcomes including technical success, endoleaks, perioperative mortality and morbidity, and graft patency were analyzed.

RESULTS

There were 13 patients (65.0%) who presented with aortic dissection, 3 (15.0%) with thoracic aortic aneurysm, 3 (15.0%) with penetrating aortic ulcer, and 1 (5.0%) with traumatic aortic disruption. Technical success rate was 100%. But one type Ia endoleak (5.0%) was noted and treated with extended endografting. One sandwiched gutter leak (5.0%) resolved spontaneously at 6 months. One sandwiched graft (5.0%) was occluded but not treated because no related complications were found. At a mean follow-up of 9.7 months (range 4-17), all the patients with aortic aneurysm, penetrating aortic ulcer, or traumatic aortic disruption had complete thrombosis of the aortic pathologies. Patients with aortic dissection had thrombosed false lumen down to the distal aortic endograft edge (12/13, 92.3%) or the celiac artery level (8/13, 61.5%). There was no neurological deficit but 2 non-procedure-related late deaths during the study period.

CONCLUSIONS

Our early experience showed that the sandwich technique with the body flossing wire to maintain blood flow to the LSA is a safe and effective method. This technique can be applied in various clinical situations with a high technique success rate. However, outcomes are preliminary and larger studies are required.

Fenestrated and Chimney Technique for Juxtarenal Aortic Aneurysm: A Systematic Review and Pooled Data Analysis

Juxtarenal aortic aneurysms (JAA) account for approximately 15% of abdominal aortic aneurysms. Fenestrated endovascular aneurysm repair (FEVAR) and chimney endovascular aneurysm repair (CH-EVAR) are both effective methods to treat JAAs, but the comparative effectiveness of these treatment modalities is unclear. We searched the PubMed, Medline, Embase, and Cochrane databases to identify English language articles published between January 2005 and September 2013 on management of JAA with fenestrated and chimney techniques to conduct a systematic review to compare outcomes of patients with juxtarenal aortic aneurysm (JAA) treated with the two techniques. We compared nine F-EVAR cohort studies including 542 JAA patients and 8 CH-EVAR cohorts with 158 JAA patients regarding techniques success rates, 30-day mortality, late mortality, endoleak events and secondary intervention rates. The results of this systematic review indicate that both fenestrated and chimney techniques are attractive options for JAAs treatment with encouraging early and mid-term outcomes.