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

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 strategies for post-dissection aortic aneurysm (PDAA)

Residual patent false lumen (FL) after type B aortic dissection (TBAD) repair is independently associated with poor long-term survival. Open surgery and endovascular repair result in good clinical outcomes in patients with AD. However, both treatments focus on proximal dissection but not distal dissection. About 13.4–62.5% of these patients present with different degrees of distal aneurysmal dilatation after primary repair. Although open surgery is the first-choice treatment for post-dissection aortic aneurysm (PDAA), there is a need for high technical demand since open surgery is associated with high mortality and morbidity. As a treatment strategy with minimal invasion, endovascular repair shows early benefits and low morbidity. For PDAA, the narrow true lumen (TL), rigid initial flap and branch arteries originating from FL have increased difficulties in operation. The aim of endovascular treatment is to promote FL thrombosis and aortic remodeling. Endovascular repair includes intervention from FL and TL sides. TL intervention techniques (parallel stent-graft, branched and fenestrated stent-graft among others) have been proven to be safe and effective in PDAA. Other FL intervention techniques that have been used in selected patients include FL embolization and candy-plug techniques. This article introduces available endovascular techniques and their outcomes for the treatment of PDAA.

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.

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.

A computational simulation of the effect of hybrid treatment for thoracoabdominal aortic aneurysm on the hemodynamics of abdominal aorta

Hybrid visceral-renal debranching procedures with endovascular repair have been proposed as an appealing technique to treat conventional thoracoabdominal aortic aneurysm (TAAA). This approach, however, still remained controversial because of the non-physiological blood flow direction of its retrograde visceral revascularization (RVR) which is generally constructed from the aortic bifurcation or common iliac artery. The current study carried out the numerical simulation to investigate the effect of RVR on the hemodynamics of abdominal aorta. The results indicated that the inflow sites for the RVR have great impact on the hemodynamic performance. When RVR was from the distal aorta, the perfusion to visceral organs were adequate but the flow flux to the iliac artery significantly decreased and a complex disturbed flow field developed at the distal aorta, which endangered the aorta at high risk of aneurysm development. When RVR was from the right iliac artery, the abdominal aorta was not troubled with low WSS or disturbed flow, but the inadequate perfusion to the visceral organs reached up to 40% and low WSS and flow velocity predominated appeared at the right iliac artery and the grafts, which may result in the stenosis in grafts and aneurysm growth on the host iliac artery.