Endovascular management of pararenal aortic aneurysms with multiple overlapping uncovered stents

Long Term Outcomes of Endovascular Treatment for Retrograde Ascending Aortic Dissection

OBJECTIVE

The optimal treatment for retrograde ascending aortic dissection (rAAD) remains unclear. In this study, the long term clinical outcomes of endovascular treatment for rAAD were investigated retrospectively, and haemodynamic remodelling of the ascending aorta was analysed.

METHODS

This retrospective, single centre study analysed clinical data of rAAD cases treated endovascularly from 2001 - 2020. Endpoints included aortic related death and re-intervention. Computational fluid dynamics (CFD) models were established to compare haemodynamic changes after endovascular repair.

RESULTS

A total of 85 patients with rAAD (mean age 52.8 ± 11.4 years, range 29.0 - 79.0 years) underwent thoracic endovascular aortic repair (T-EVAR). Technical success was achieved in 73 patients (86%). In hospital death occurred in one patient (1%). During the 75 month median follow up (interquartile range 54, 101 months), all cause mortality was 7% (6/84, including two aortic related deaths). Overall survival rates for one, five, and ten years were 98.8%, 92.7%, and 88.6%, respectively. Sixteen aortic related adverse events were observed in 15 patients during follow up, including two proximal stent graft induced new entries (SINEs), two distal SINEs, and 12 primary endoleaks into the false lumen. Secondary endoleak was not observed. The free from aortic related event rates for one, five, and ten years were 77.3%, 74.3%, and 71.5%, respectively. Complete thrombosis or disappearance of the false lumen in the ascending aorta was observed in all cases. The true lumen diameter of the ascending aorta increased statistically significantly from 31.8 ± 5.2 mm (range 15.8 - 40.8 mm) to 35.4 ± 3.5 mm (range 28.3 - 44.0 mm) (p < .001) at the last follow up. CFD analysis showed that the median wall shear stress in the ascending aorta statistically significantly decreased from 16.4 Pa to 12.4 Pa (p = .006).

CONCLUSION

Encouraging short and long term outcomes were demonstrated using T-EVAR for rAAD, suggesting that it may represent a treatment alternative to open repair in selected cases.

The hemodynamic effect of eccentricity in visceral branched aneurysms with multilayer stents

It is preliminarily acknowledged that multilayer stent (MS) is a promising alternative technology in the treatment of visceral branched aneurysms, but hemodynamic consequences of eccentricity in such aneurysms with MS are less examined. In this work, we performed a time-dependent simulation of branched aneurysms of various eccentricities with different stent layers, and thrombosis-related parameters, such as time-averaged wall shear stress (TAWSS), oscillating shear index (OSI), and relative residence time (RRT), were also analyzed. Our results revealed that MS can generally restore laminar flow inside the stent, and allow proper perfusion to vital organs while also fostering a relatively secluded hemodynamic environment for thrombosis formation. Particularly, a flow in the aneurysm sac communicating between the main artery and side branch forms at early systole. However, MS fails to completely eliminate detrimental flow impingement after peak systole, which may hinder aneurysm recovery, especially in the cases of eccentric aneurysms. Therefore, saccular aneurysms should be treated with more caution than fusiform aneurysms. And further therapeutic attempts to keep both perfusion in the proximal region of the aneurysm and isolation in the distal region of the aneurysm should be considered.

Endovascular treatment of complicated aortic aneurysms using a modified flow-diverting strategy: Mid- to long-term outcome from a multicenter cohort study

OBJECTIVES

Frequently reported adverse events following flow-diverting stents' treatment of aortic aneurysms indicate further refinements of this technique are required. This study aims at evaluating the clinical efficacy of an improved flow-diverting strategy.

METHODS

A modified flow-diverting procedure was utilized in selected patients, in which stent-grafts were used to cover the non-branched segment of the aneurysmal lesion while flow-diverting multilayered bare metal stents were applied to cover the reno-visceral segment. The safety and efficacy of this joint procedure were assessed by regular follow-up.

RESULTS

We screened 497 patients and included 67 cases (mean age: 67.07 ± 12.14 years; 53 males) between February 2012 and March 2018. The median number of stent-grafts and bare metal stents used in the procedure were 1 (range: 1 to 3) and 3 (range: 2 to 4), respectively. During a mean follow-up period of 34.54 ± 20.28 months, aneurysm maximum diameter decreased from 64.79 ± 10.31 to 59.32 ± 10.20 mm (p = 0.002), while sac thrombosis ratio increased from 26.01±10.99% to 98.46±4.84% (p<0.001). Aneurysm-related death or conversion to open repair was documented in three patients. The majority side-branches (198/201) remained patent during follow-up. Overall clinical success rate reached 91.04% (61/67).

CONCLUSIONS

The joint procedure is characterized by significant aneurysm thrombosis along with high aneurysm stabilization/shrinkage and side-branches' patency rate. It might represent a potential improvement of the flow-diverting strategy in treating complex aortic lesions, yet large-scale, prospective, and randomized trials are anticipated to draw a robust conclusion.

ADVANCES IN KNOWLEDGE

The joint procedure could potentially exclude complex aortic aneurysms from circulation while maintaining the collateral branches.

Multilayer bare stent technique in treating intact mycotic suprarenal aortic aneurysm: a case report

Background

Invasive aspergillosis (IA) related mycotic aortic aneurysm is rare in immunocompetent patient. The endovascular therapy remains controversial due to potential risk of graft infection, while the suprarenal cases might face catastrophic complications during open surgery.

Case summary

We presented an IA case with suprarenal abdominal aortic aneurysm confirmed by joint effusion. Multilayer bare stent technique was performed to preserve visceral blood flow and promote aneurysmal thrombus formation, along with antifungal treatment. Two years of follow-up revealed complete aneurysm thrombosis without evidence of infection.

Discussion

Fungal infection that affects the aorta is difficult to recognize due to often negative blood cultures. Close observation is recommended in case of suspicion of mycotic aneurysms. Multilayer bare stent technique can restore luminal laminar blood flow and reduce the risk of infection in intact mycotic suprarenal aortic aneurysm.

Biomechanical insight of the stent-induced thrombosis following flow-diverting strategy in the management of complicated aortic aneurysms

BACKGROUND

The flow-diverting stent (FDS) emerges as an alternative strategy in treating complicated aortic aneurysms. However, the biomechanical behavior of the stent-induced thrombus (SIT) remains little understood. This study sought to investigate the impact of SIT on aneurysm wall stress and strain distribution and offer basic evidences for its large-scale application.

METHODS

Aortic aneurysms treated with FDS and followed up over 5 years were selected. Case-specific models were created based on the pre-operative and 12 months follow-up imaging. The aortic central line was generated, perpendicular to which the slice with maximum aneurysm diameter was selected for two-dimensional modeling. Pre- and post-stenting models were compared, with emphasis laid on wall stress distribution and risk factors leading to local stress concentration. Clinical follow-up data was recorded to verify the biomechanical findings.

RESULTS

A total of 6 cases (3 females, average age 56.3±17.2 years) were enrolled in this study. Complete sac thrombosis was documented in 5 cases at 12 months, while residual perfusion was seen in the remaining one. With the formation of SIT, the average wall tensile stress dropped from 58.60±11.11 KPa to 23.56±12.05 KPa (P=0.001) at diastolic phase, and from 88.00±15.94 KPa to 36.02±18.31 KPa (P=0.001) at systolic phase. Intra-wall calcium plaque and irregular, spontaneous intraluminal thrombus were recognized as risk factors for local stress concentration, which could be mitigated by the regular, well-organized SIT. Long-term follow-up at 5 years showed significant aneurysm shrinkage from 57.7±16.2 mm to 51.0±13.7 mm (P=0.009).

CONCLUSIONS

The formation of SIT after FDS implantation might protect the aneurysm by reducing the wall tensile stress and erasing the local stress concentration. Clinical follow-up data seems to support the biomechanical role of SIT, but a larger study cohort is needed. A comprehensive understanding of SIT including both biomechanical and biological perspectives is warranted to draw an exhaustive conclusion.

Hemodynamic Effects of Multiple Overlapping Uncovered Stents on Aortic Dissection: Surgical Strategies and Implications for False Lumen Thrombosis

PURPOSE

Multiple overlapping uncovered stents (MOUS) are employed to promote false lumen thrombosis in the aortic dissections (AD), when the tears are in close vicinity to the branch vessels. However, the overall rate of false lumen thrombosis remains unsatisfactory. This study was performed to investigate the hemodynamic influence of MOUS on aortic dissection to shed some light on the mechanism of post-stenting false lumen thrombosis.

METHODS

An anatomically accurate computational fluid dynamics model was developed to investigate the hemodynamics of AD. A parametric study was carried out to demonstrate the hemodynamic influence of MOUS in various post-surgery scenarios featuring the representative surgical strategies involving MOUS.

RESULTS

The use of reduced-porosity MOUS slowed the blood flow in the false lumen and decreased the wall shear stress. MOUS depressed the false lumen and enlarged the true lumen, without significantly altering the blood outflow distribution among the branch vessels. Compared with MOUS-alone and stent graft-alone scenarios, the combination of MOUS and stent graft generated a substantially large region of stagnant flow. The active flow was confined to an area in close vicinity to the tears covered by the MOUS, which perfuse the right renal artery in the false lumen.

CONCLUSIONS

MOUS helps to generate a favored hemodynamic environment for thrombus formation in the false lumen. Application of MOUS along with covered stent grafts may represent a more effective treatment for AD than utilizing MOUS or stent graft alone.

Treatment of High Surgical Risk Thoracoabdominal Aortic Aneurysms with Stent Graft and Multilayer Bare Stents Joint Technique: Mid-Long-Term Clinical Results

BACKGROUND

This study aims to present the performance data on stent-graft and multilayer bare stents (MBS) joint technique in the treatment of high-risk thoracoabdominal aortic aneurysm (TAAA).

METHODS

From May 2012 to December 2015, 8 selective TAAA cases (ages 46-75 years) ineligible for surgical repair underwent the stent-graft and MBS joint procedure, and were closely followed up for a median of 32 months (range 14-58). Using computed tomography images, the aneurysm size, luminal blood flow diameter, and the covered visceral branches were analyzed.

RESULTS

Technical success was achieved in all patients (100%, 8/8). Twenty-four visceral branches were covered by MBS in total. There was no complication or death during hospital stay. During follow-up period, no death or complication occurred. Aneurysm shrinkage (maximum diameter decrease ≥5 mm) was observed in 7 patients. No aneurysm expansion was observed. Total aneurysm sac thrombosis was observed in all patients. The majority of covered side branches (23/24) were successfully preserved. No visceral ischemia or bleeding complications was observed during follow-up.

CONCLUSIONS

Total endovascular repair of TAAA using stent-graft and MBS joint technique may be a safe and effective alternative in high surgical risk patients. More approving clinical evidences about the safety and efficacy of this procedure are anticipated.

Treatment of aortic dissecting aneurysm involving visceral arteries with multi-layer bare stents

OBJECTIVE

Aortic dissecting aneurysms involving visceral arteries are difficult for clinical treatment. This study aimed to explore the clinical efficacy and safety of multi-layer bare stents technique in the treatment of aortic dissecting aneurysms involving visceral arteries.

METHOD

The clinical data of 16 patients of aortic dissecting aneurysm involving visceral artery treated with multi-layer bare stents technique from March 2013 to March 2017 in Tianjin Medical University General Hospital were retrospectively analyzed. To explore the clinical efficacy, the number of stents applied, postoperative aortic dissecting thrombosis and postoperative cumulative branch arterial patency of the16 patients.

RESULTS

The operations of the 16 patients were successfully completed without peri-operative death cases. The 16 patients were implanted with 39 bare stents with an average of 2.44 per person. There were 2 cases with 1 stent, 8 cases with 2 stents and 7 cases with 3 stents. One month after the operation, CTA showed complete thrombosis in the arterial dissection in 4 cases (25.0%), partial thrombosis in 12 cases (75.0%); CTA showed that celiac artery, left and right renal arteries, and superior mesenteric artery were all unobstructed. There were 4 cases (25.0%) of dissecting artery with reduced diameter, 12 patients (75.0%) without changes in the diameter, and no diameter expanding cases.

CONCLUSION

The treatment for aortic dissecting aneurysm involving the visceral arteries using multi-layer bare stents technique is safe and reliable with a higher patency rate of postoperative accumulated branch arteries.

Endovascular Treatment of Patients with Isolated Mesenteric Artery Dissection Aneurysm: Bare Stents Alone Versus Stent Assisted Coiling

OBJECTIVE

The aim was to evaluate the outcomes of endovascular treatment with bare stents alone versus stent assisted coiling in isolated mesenteric artery dissection (IMAD) aneurysms.

METHODS

Patients with an IMAD aneurysm who underwent endovascular stenting between February 2010 and February 2017 at one of three institutions were included in this study. Data regarding technical success, procedure time, symptom resolution, complications, changes in IMAD aneurysm, and stent patency were recorded.

RESULTS

A total of 38 patients (35 men) were included, 27 treated with bare stents alone and 11 treated with stent assisted coiling. Technical success was achieved in 100% of patients treated with bare stents and in 81.8% of those treated with stent assisted coiling (p = 0.078). The mean procedure times were 62.6 ± 5.3 min for treatment with bare stents and 116.4 ± 8.4 min for stent assisted coiling (p < 0.001). A total of 23 patients had persistent symptoms before stenting; all symptoms were resolved within 3.0 ± 0.7 days. No procedure related major complications occurred. Over 30.2 ± 18.1 months of follow up, complete resolution of the IMAD aneurysm was achieved in all patients; good stent patency and in stent re-stenosis were achieved in 65.8% and 34.2% patients, respectively. There were no occlusions of the stented arteries.

CONCLUSIONS

Bare stents alone and stent assisted coiling have high technical success rates and demonstrate good intermediate patency in patients with an IMAD aneurysm. Bare stents alone may serve as an alternative to stent assisted coiling for the management of IMAD aneurysm.

Endovascular Treatment of Distal Tears Located in the Reno-Visceral Segment with Bare-Metal Stents and Coils in a Complicated Type B Aortic Dissection

The purpose of the study was to provide an endovascular strategy of treating patent reentries adjacent to visceral branches in the management of aortic dissections. A 45-year-old male who had received endovascular treatment for a type B aortic dissection was again admitted for his intermittent abdominal pain. Distal tears located in the reno-visceral segment were left untreated in the initial procedure and were thought to be related to the expansion of the false lumen during follow-up. Another endovascular surgery aiming at sealing these reentries was then performed using the concept of low-porosity flow-diverting stents and coiling technique. Postoperative angiogram revealed a significant decrease in inflow rate through the distal tears, and further computed tomography scan showed a decrease in maximum aortic diameter during the follow-up. With the assistance of coils, the low-porosity bare stents showed the potential to significantly decrease the inflow rate and accelerate the thrombosis of the false lumen. Clinical success achieved in this case study proposes an endovascular strategy in treating the reentries without disturbing the adjacent branches, while its safety and efficacy are still waiting for the verification.

Influence of overlapping pattern of multiple overlapping uncovered stents on the local mechanical environment: A patient-specific parameter study

BACKGROUND

Multiple overlapping uncovered stents (MOUS) system has shown potentials in managing complex aortic aneurysms with side branches involvement. It promotes the development of thrombus by modulating local flow pattern that reduces the wall tension, while maintaining patency of side branches. However the modulation of local hemodynamic parameters depends on various factors that have not been assessed comprehensively.

METHODS

Aneurysm 3D geometry was reconstructed based on CT images. One-way fluid-structure interaction analysis was performed to quantify structural stress concentration in the wall, and changes of blood velocity, wall shear stress (WSS), oscillatory shear index (OSI), relative residence time (RRT) and pressure in the sac due to the stent deployment.

RESULTS

High structural stress concentration due to stent deployment was found in the landing zone and it increased linearly with the number of stents deployed. The wall tension in the sac was unaffected by the stent deployment. Stress within the wall was insensitive to the different overlapping pattern. After one stent was deployed, the mean flow velocity in the sac reduced by 36.4%. The deployment of the 2nd stent further reduced the mean sac velocity by 10%. WSS decreased while both OSI and RRT increased after stent deployment, however pressure in the sac remained nearly unchanged. Except for the cases with complete stents struts alignment, different overlapping pattern had little effect on flow parameters.

CONCLUSIONS

Mechanical parameters modulated by the MOUS are insensitive to different overlapping pattern suggesting that endovascular procedure can be performed with less attention to the overlapping pattern.

Endovascular Treatment of Thoracoabdominal Aorta Aneurysm by the Combination of a Stent Graft with Multiple Overlapping Bare Stents

A 41-year-old male diagnosed with Crawford III thoracoabdominal aorta aneurysm (TAAA) was treated using a completely endovascular approach. After the combined implementation of 4 overlapping bare stents and a stent graft, TAAA was excluded while the 4 visceral arteries were reserved. Follow-up computed tomography scans at 3 and 6 months showed that the aneurysm had almost disappeared, while the vital branches remained open. This case may provide an acceptable alternative choice for treating TAAA in selected patients.

Hemodynamic Study of Flow Remodeling Stent Graft for the Treatment of Highly Angulated Abdominal Aortic Aneurysm

This study investigates the effect of a novel flow remodeling stent graft (FRSG) on the hemodynamic characteristics in highly angulated abdominal aortic aneurysm based on computational fluid dynamics (CFD) approach. An idealized aortic aneurysm with varying aortic neck angulations was constructed and CFD simulations were performed on nonstented models and stented models with FRSG. The influence of FRSG intervention on the hemodynamic performance is analyzed and compared in terms of flow patterns, wall shear stress (WSS), and pressure distribution in the aneurysm. The findings showed that aortic neck angulations significantly influence the velocity flow field in nonstented models, with larger angulations shifting the mainstream blood flow towards the center of the aorta. By introducing FRSG treatment into the aneurysm, erratic flow recirculation pattern in the aneurysm sac diminishes while the average velocity magnitude in the aneurysm sac was reduced in the range of 39% to 53%. FRSG intervention protects the aneurysm against the impacts of high velocity concentrated flow and decreases wall shear stress by more than 50%. The simulation results highlighted that FRSG may effectively treat aneurysm with high aortic neck angulations via the mechanism of promoting thrombus formation and subsequently led to the resorption of the aneurysm.

Hemodynamic insight into overlapping bare-metal stents strategy in the treatment of aortic aneurysm

Clinical trials have shown overlapping bare-metal stents provoke effective thrombus clot within the aneurysm sac and shrinkage of the aneurysm by directly regulating the hemodynamics. To gain insight into the hemodynamic mechanism of the technique, three cases of simplified thoracic aortic aneurysm models (with no stent, a single stent and two overlapped stents deployed within the aneurysm sac) were studied and compared in terms of time-varying velocity and shear rate, time-averaged wall shear stress (TAWSS), oscillating shear index (OSI) and relative residence time (RRT). The results demonstrated that the overlapping stents' strategy was more effective in reducing the velocity of blood flow within the aneurysm, especially for the area near the aneurysm wall. Stenting induced a dramatic change trend of shear rate during the cardiac cycle, in which a very high shear rate (>10,000 s(-1)) during the systole and a quite low shear rate (<1000 s(-1)) during the diastole were observed, respectively. Moreover, reduced TAWSS and OSI and elevated RRT values were observed on the aneurysm wall after stent placement. The effects of stenting on the shear rate, TAWSS, OSI and RRT in the aneurysm would be significantly enhanced by two overlapped stents. The present findings therefore indicated that, the overlapping bare-metal stents can isolate the aneurysm effectively and may create a favorable hemodynamic environment provoking platelets activation and aggregation within the aneurysm, which may promote thrombus formation/growth there, hence contribute to degradation of the aneurysm.

Management of complicated aortic aneurysms using multiple overlapping uncovered stents: mid-term outcome from a cohort study

This study sought to report the mid-term outcome of a modified flow-diverting strategy in the treatment of complicated aortic aneurysms of different morphology. Historical data suggested aortic aneurysm expansion and rupture after endovascular treatment with current commercial flow-diverters, indicating the essentiality of further investigation of this technique prior to its large-scale clinical application. An alternative flow-diverting strategy using layer-by-layer assembled multiple overlapping uncovered stents was employed in this study. The treatment outcome in aneurysms of different morphology (saccular, fusiform, and dissecting) was assessed during a mid-term follow-up period.Of 42 patients enrolled in this study (30 male, mean age: 63.3 years), technical success was achieved in 40 cases. During an average follow-up period of 20.9 months, mean aneurysm diameter shrunk from 53.4 ± 13.6 mm to 48.8 ± 13.9 mm (P < 0.001), while stent-induced sac thrombosis ratio increased significantly (18.1 ± 14.9% to 93.6 ± 9.5%, P < 0.001). The majority of side branches (74/76 major visceral branches, 237/244 minor segmental arteries), covered by 3.3 stents on average, maintained their patency after stenting. Saccular aneurysms manifested the highest thrombus deposition speed (18/20 were totally thrombosed within 12 months) and most significant shrinkage (51.4 ± 13.3 mm pre-operatively vs 43.5 ± 10.2 mm during follow-up, P < 0.001) compared with fusiform and dissecting aneurysms. This modified flow-diverting strategy could be a feasible alternative in the management of complicated aortic aneurysms where vital branches need to be preserved. The treatment outcome may depend on the aneurysm type. Further studies with larger patient cohort and longer follow-up are required to substantiate these results.

Total endovascular repair of thoracoabdominal aortic aneurysms with non-customized stent grafts

BACKGROUND

Total endovascular repair of thoracoabdominal aortic aneurysms with customized branched or fenestrated endografts could be technically challenging outside large-volume centers. This study aims to describe a new endovascular strategy for use of both noncustomized stent grafts and flow-diverting stents in treating complicated thoracoabdominal aortic aneurysms.

METHODS

Patients diagnosed with thoracoabdominal aortic aneurysms and deemed unfit for open surgical repair were recruited. The aim of the procedure was to cover the renovisceral segment of the aorta with flow-diverting uncovered stents, while covering the remaining aneurysm with stent grafts. Aneurysm morphologic evolution and the patency of the visceral branches were assessed at follow-up.

RESULTS

Between February 2012 and August 2013, 6 selective patients (4 men, mean age 58 years) underwent the novel joint procedure. During mean follow-up of 14 months, aneurysm shrinkage (maximum diameter decrease ＞5 mm) was demonstrated in 4 patients and aneurysm stabilization (maximum diameter decrease ＜5 mm) was observed in 2 patients. No aneurysm expansion was observed in any participants. Mean aneurysm diameter decreased from 65.0±8.8 mm to 58.5±12.2 mm (p=0.054), with a significant increase in average sac thrombus deposition volume (sac thrombosis ratio increased from 23.3%±7.4% to 98.0%±3.3%, p＜0.001). The majority of side branches (23 of 24) were successfully preserved.

CONCLUSIONS

Complete endovascular repair of thoracoabdominal aortic aneurysms with this novel joint procedure may be a feasible alternative in high surgical risk patients. Further validation of this technique is required to substantiate these results.

Multiple overlapping uncovered stents as an alternative flow-diverting strategy in the management of peripheral and visceral aneurysms

OBJECTIVE

In this study we aimed to report on the midterm outcome of multiple overlapping uncovered stents in the treatment of peripheral and visceral aneurysms, and analyze the possible factors affecting the treatment efficacy.

METHODS

Data of patients who were regularly followed up over 24 months were retrospectively reviewed. Descriptive statistics were applied to present aneurysm thrombosis process and diameter change at each follow-up point, and a comparison with the baseline level was performed. Patients were divided into a totally thrombosed (TT) group and a residual perfusion (RP) group according to the sac thrombosis ratio (thrombus volume to sac volume ratio) at 3, 6, and 12 months of follow-up. Aneurysm shrinkage in the two groups was compared to explore the effect of the initial RP on the treatment outcome. Patients were also grouped based on their aneurysm morphology (saccular/fusiform). The aneurysm sac thrombosis speed (time to thrombosis) and diameter decrease (DD) ratio (percentage of DD) were compared between the two groups to understand the influence of aneurysm shape on the treatment efficacy.

RESULTS

Of the 64 patients treated, the initial 37 patients (25 male; average age, 55.5 ± 13.0 years) were enrolled into this study. Technical success rate was 100%. All patients were regularly followed up. At 24 months, 94.6% aneurysms (35/37) were TT, and the maximum aneurysm diameter decreased from 36.5 ± 9.7 mm preoperatively to 23.6 ± 7.7 mm (P < .001). Overall clinical success rate (complete thrombosis and shrinkage/stabilization of the aneurysm without aneurysm-related mortality) reached 94.6% in the study cohort. Most side branches (31/33) covered by the bare stent stayed patent during follow-up. Initial sac RP at 3, 6, and 12 months might not fully affect the final aneurysm DD ratio (TT group: 0.37 ± 0.09, 0.35 ± 0.09, and 0.35 ± 0.09; compared with the RP group: 0.33 ± 0.09, 0.36 ± 0.11, and 0.36 ± 0.13; P = .153, .964, and .418, respectively). At 3 and 6 months follow-up, saccular aneurysms (n = 29) seemed to have a faster thrombosis speed compared with fusiform aneurysms (78.1 ± 26.8% and 83.9 ± 21.8% vs 47.0 ± 24.4% and 63.9 ± 22.6%; P = .004 and .013, respectively), but there was no significant difference in aneurysm shrinkage ratio at 24 months between the two groups (0.36 ± 0.10 vs 0.33 ± 0.06; P = .357).

CONCLUSIONS

Multiple overlapping uncovered stents could be a feasible option for the endovascular treatment of peripheral and visceral aneurysms. Neither the aneurysm shape nor the initial sac RP would affect the midterm treatment outcome. Further validation of this technique is required to substantiate these results.