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

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.

Endovascular repair of visceral artery aneurysms and pseudoaneurysms in 159 patients: twelve years' experience of clinical technique

OBJECTIVES

The purpose of this study was to evaluate the therapeutic efficacy and safety of endovascular treatment for patients with visceral and renal artery aneurysms (VRAAs). Twelve years of experience with interventional procedures and treatment options in our center were also worth discussing.

METHODS

From January 2009 to December 2020, clinical data of 159 consecutive patients with VRAAs were retrospectively analyzed. Patients' demographic and clinical data were recorded, and the safety and efficacy of endovascular therapy were evaluated. In addition, interventional procedures were also described.

RESULTS

A total of 159 patients underwent angiography, and 154 patients were successfully treated with endovascular therapy, with a technical success rate of 96.9%. Of the 154 patients with successful endovascular therapy, 3 patients died within 30 days of treatment, with a 30-day mortality rate of 1.9%, and the remaining patients were clinically successful, with a clinical success rate of 98.1%. Fifty-seven patients underwent emergency interventional treatment due to ruptured aneurysm. There were statistically significant differences in hemoglobin before and after emergency treatment (78.5 ± 22.0 g/dL vs. 93.8 ± 15.0 g/dL, P = 0.00). No other serious complications occurred except death in 3 patients.

CONCLUSION

Endovascular treatment of VRRAs is safe and effective and can significantly improve the symptoms of patients, especially those with ruptured aneurysms.

Endovascular Double-Layer Bare Stent Placement in the Treatment of Posttraumatic Pseudoaneurysm

Objective

To investigate the efficacy and safety of endovascular double-layer bare stent placement for the treatment of traumatic false aneurysm (TFA).

Methods

This is a retrospective review of five patients with TFA undergone double-layer bare stent placement in our center between February 2011 and August 2020. There are 2 males and 3 females aged 29-65 years, with an average age of 43 years. One case suffered from common carotid artery pseudoaneurysm, and four cases suffered superficial femoral artery pseudoaneurysm.

Results

The endovascular interventional treatment was successful in all 5 patients, and the pseudoaneurysms disappeared after treatment. No TFA recurrence and no complications such as instent stenosis, stent migration, stent fracture, endoleak, and infection were observed during the 3-99-month follow-up period.

Conclusion

For the treatment of TFA, endovascular interventional therapy with double-layer bare stent was minimally invasive, safe, and effective with fewer complications. It could preserve all branches of parent artery and had the advantage of lower cost. It can be used in the treatment of TFA in selected cases. However, further clinical researches with larger cohorts are needed before its long-term efficacy can be completely clarified.

Endovascular treatment with stenting of celiac artery aneurysms

This study aimed to detail the clinical outcomes of patients suffering from celiac arterial aneurysm (CAA) that underwent treatment via stent occlusion.This is a single-center, retrospective study. A total of 8 consecutive CAA patients were treated via stent occlusion from March 2014 to September 2018 at our hospital. Follow-up computed tomography was conducted after stenting at 1, 3, 6, and 12-month time points and every year thereafter. Both short- and long-term outcomes were assessed.In total, 8 stents were inserted into these 8 patients, with 2 being uncovered and 6 being covered stents. In 2 patients, stents were positioned in the celiac artery, while in the remaining 6 patients they were placed in the celiac and common hepatic arteries. The median operative duration was 66 minutes. No patients exhibited procedure-associated complications, and the median follow-up duration was 39 months (range: 18-72). Abdominal contrast-enhanced CT analyses of these patients exhibited stent and distal artery patency in 100% of patients, together with CAA obliteration. Visceral necrosis did not occur in any patients over the follow-up period.Stent occlusion can be safely and effectively used to treat CAA patients.

A systematic review and meta-analysis of the performance of flow-diverting stents in the treatment of peripheral and visceral artery aneurysms

OBJECTIVE

This meta-analysis aims to evaluate the safety and efficacy of flow-diverting stents (FDS) in treating peripheral and visceral artery aneurysms (PAA/VAAs).

BACKGROUND

Though rare, PAA/VAAs can represent a life-threatening condition due to their propensity of rupture. The FDS emerges as a new solution to exclude these aneurysms while maintaining collateral branches, but convincing evidence is lacking on its clinical effectiveness.

METHODS

A systematic literature search was performed to identify studies related to FDS in treating PAA/VAAs. The preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement was applied to guide the data extraction, quality assessment, and synthesis of outcomes of interest. Random effect models were applied to calculate the event rates of major endpoints. OpenMeta[Analyst] software was used for statistical analysis.

RESULTS

Of 130 records screened, 10 cohort studies (including 220 patients, average age: 66.0 years, 78.4% male) were enrolled in the meta-analysis. Pooled data suggested a technical success rate of 98.5% (95% CI: 97.0-100%). During a mean follow-up period of 14.1 months, 93.6% (95% CI: 88.6-98.5%) side branches remained patent, 89.8% (95% CI: 84.3-95.3%) aneurysms were totally thrombosed, whereas shrinkage/stabilization of the aneurysm was documented in 93.4% (95% CI: 88.4-98.4%) cases. The primary stent patency rate was estimated to be 87.9% (95% CI: 81.0-94.8%). Overall clinical success was achieved in 83.2% (95% CI: 74.4-92.0%) patients.

CONCLUSIONS

The FDS features a potential advantage of preserving side branches while inducing sac thrombosis and aneurysm shrinkage/stabilization. Further prospective, comparative studies in larger patient cohorts are anticipated to draw a robust conclusion.

A Promising Treatment of Distal Entry Tears Located in Branched Area of Abdominal Aorta With Coil-Stent Tear Occlusion Device: an Animal Experiment

This study aims to evaluate the effect of coil-stent tear occlusion device in treating entry tears located in branched area of abdominal aorta. An abdominal aortic dissection animal model was constructed by mesh suturing method. The animal models were treated by the occlusion device and were evaluated by computed tomography angiography (CTA) 1 month later. Eighteen pigs were adopted in the abdominal aortic dissection modeling experiment, two of them died of cardiopulmonary arrest during the operation. Sixteen models survived, two of them were found complete false lumen thrombosis by CTA 3 days after the operation. The false lumen kept patency in the remaining 14 cases which were then implanted with the occlusion device. The procedure was successful in 13 cases except for one. The coil-stent tear occlusion device provides a novel method for tears located in the branched area of abdominal aorta, and is worth of further study.

Endovascular Repair of 40 Visceral Artery Aneurysms and Pseudoaneurysms with the Viabahn Stent-Graft: Technical Aspects, Clinical Outcome and Mid-Term Patency

PURPOSE

Endovascular repair of true visceral artery aneurysms (VAAs) and pseudoaneurysms (VAPAs) with stent-grafting (SG) can simultaneously allow aneurysm exclusion and vessel preservation, minimizing the risk of ischemic complications. Our aim was to report a single-center experience on SG of visceral aneurysms, focusing on technical aspects, clinical outcome and mid-term patency.

MATERIALS AND METHODS

Consecutive patients affected by VAAs-VAPAs and submitted to endovascular treatment were retrospectively reviewed, and SG cases with the self-expandable peripheral Viabahn stent-graft were analyzed (2003-2017). Aneurysm type, patient number, SG clinical setting, procedural data, peri-procedural complications, technical success, 30-day clinical success, 30-day mortality and follow-up period (aneurysm exclusion, stent-graft patency, ischemic complications) were analyzed.

RESULTS

SG was performed in 40 patients (24 VAPAs/16 VAAs) and in 44 procedures (25 in emergency, 19 in elective treatments), via transfemoral in 37 cases (transaxillary in 7 cases). One peri-procedural complication was recorded (a splenic artery dissection successfully converted to transcatheter embolization). The overall technical and clinical success rates were, respectively, 96 and 84%, with excellent trend in elective treatments (both 100%). Overall 30-day mortality was 12.5% (septic shock after pancreatic surgery). Stent-graft thrombosis occurred in 2 patients within 3 months, with aneurysm exclusion and without ischemic complications. Stent-graft patency and aneurysm exclusion were confirmed at 6, 12 and 36 months in 18, 12 and 7 patients, respectively.

CONCLUSION

SG of VAAs and VAPAs was safe and effective, particularly in elective treatments. The Viabahn stent-graft, flexible and without shape memory, is suitable for endovascular repair of tortuous visceral arteries.

Endovascular Treatment of Visceral Artery Aneurysms and Pseudoaneurysms in 100 Patients: Covered Stenting vs Transcatheter Embolization

Purpose: To retrospectively report a large single-center experience of visceral artery aneurysms (VAAs) and pseudoaneurysms (VAPAs) treated with covered stenting (CS) as the first therapeutic option vs transcatheter embolization (TE). Methods: One hundred patients (mean age 59±14 years; 58 men) underwent 59 elective and 41 emergent endovascular procedures to treat 51 VAAs and 49 VAPAs. Seventy patients had TE and 30 received CS (27 Viabahn and 3 coronary stent grafts). Both TE and CS were performed in 10 cases. Results: Technical success was 96% (97% CS, 96% TE), and 30-day clinical success was 83% (87% CS, 81.4% TE). Four major complications occurred; 30-day mortality was 7%, mainly due to septic shock following pancreatic surgery. The midterm follow-up was 20.8 months in the total population and 32.8 months in the CS group. More than 6 months after CS all aneurysms remained excluded; stent patency was achieved in 88%. Twelve CS patients with >3 years’ follow-up had maintained stent patency. Conclusion: In endovascular treatment of visceral aneurysms, covered stenting was feasible in 30%. CS showed a slightly better efficacy than TE and good midterm patency. The Viabahn covered stent seems to be suitable for endovascular repair of tortuous visceral arteries affected by true or false aneurysms.

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.

Prognostic Impact of Blood Pressure Variability on Aortic Dissection Patients After Endovascular Therapy

Hypertension has been deemed as a pivotal risk factor for the development of aortic dissection; however, the importance and prognostic significance of blood pressure variability (BPV) in aortic dissection are always ignored. A total of 173 acute type B aortic dissection patients were enrolled in and retrospectively reviewed between January 2009 and November 2013. There were 74 patients with high BPV and 99 with low BPV stratified by preoperative mean BPV. Technical success was achieved in all patients. The proportions of hypertension and general anesthesia were significantly higher in the high BPV group (70.3% vs 55.6% and 77% vs 62.6%, P = 0.049 and 0.043, respectively). The risk of aorta-related death in the high BPV group was apparently higher than the low BPV group (28.4% vs 9.1%, P = 0.001). By performing multivariable logistic regression, we found history of hypertension was likely to be a risk factor of BPV (95% confidence interval [CI]: 1.010-3.911), and high BPV was an independent predictor of aorta-related death (95% CI: 1.671-9.587). The difference of aorta-related mortality was pronounced between high and low BPV subgroups regardless of the refractory hypertension (41.4% vs 14.3% and 20.0% vs 7.0%, P = 0.023 and 0.037, respectively). The thrombosis ratio of false lumen was significantly higher in the low BPV group at 3-month (72.4 ± 17.5% vs 51.8 ± 11.6%, P < 0.001) and 6-month (86.4 ± 9.1% vs 69.7 ± 7.9%, P < 0.001). High BPV is an independent risk factor for the prognosis of aortic dissection. Further studies on BPV might provide new preventive and therapeutic strategies for aortic dissection.

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.