Severe visceral ischemia and death after multilayer stent deployment for the treatment of a thoracoabdominal aortic aneurysm

Late surgical conversion of failed Multilayer Flow Modulator stenting in thoraco-abdominal aneurysms

OBJECTIVES

The aim of this study was to report the outcomes of open or hybrid repair of failed thoraco-abdominal aortic aneurysm endovascular treatment with Multilayer Flow Modulator (MFM) stents.

METHODS

All patients who underwent open or hybrid repair of a failed MFM aortic treatment were retrospectively analysed. Perioperative and postoperative data, as well as midterm survival, were assessed.

RESULTS

Between 2013 and 2020, 39 patients received an open or hybrid conversion after endovascular treatment. Five of them [13%; 4 males; median age 68 years (interquartile range 66-76)] were previously treated with aortic MFM stents (Cardiatis, Isnes, Belgium). Among these, the median interval between index repair and conversion was 84 months (interquartile range 75-84). The median aneurysm diameter was 9.6 cm (interquartile range 8-10). Renovisceral vessels steno-occlusion was highly prevalent: 2 renal arteries were occluded; 3 coeliac trunks, 2 renal arteries and 1 superior mesenteric artery had a >70% ostial stenosis. Open standard thoraco-abdominal aneurysm conversion was performed in 3 fit patients, while a hybrid approach with visceral debranching and tube endografting was performed in 2 high-risk patients. Two patients (2 open repairs) died intraoperatively, and 1 (hybrid repair) postoperatively. The 2 successfully treated patients are alive at 4- and 34-month follow-up, respectively, with patent visceral branches.

CONCLUSIONS

Open or hybrid thoraco-abdominal aortic aneurysm treatment after failed endovascular aortic repair with MFM stents might be the only surgical option to address sac enlargements and ruptures or branch-related failures. However, both procedures had a poor prognosis due to both the impaired preoperative patient's status and the surgical complexity in the presented series.

A systematic review and meta-analysis of the streamliner multilayer flow modulator stent for treatment of complex aortic lesions

OBJECTIVE

We evaluated the safety and efficacy of multilayer flow modulator (MFM) stents (Cardiatis, Isnes, Belgium) for the treatment of complex aortic lesions.

METHODS

A systematic electronic research was conducted for studies reported from December 2008 to May 2020. Data extracted from 15 eligible case series (CS) were appropriately pooled and analyzed in a meta-analysis. The patient baseline characteristics were recorded, and 16 outcomes of interest were studied. The primary end points included 30-day all-cause and aneurysm-related mortality, aneurysm-related mortality at 1 year, vessel patency, and any endoleaks, ruptures, reinterventions, and aneurysm exclusion at the end of follow-up.

RESULTS

A total of 39 studies (15 CS and 24 case reports), involving 429 patients, met the inclusion criteria. Overall, 436 lesions were treated, and 1521 aortic branches were covered by the multilayer stent. The mean follow-up for the 15 CS with 404 patients was 14.6 months. Compliance with the instructions for use was reported by eight CS, with 75% of the procedures performed within the instructions for use. However, 41% of the patients reported by 12 CS had undergone a previous aortic intervention. The pooled 30-day all-cause and 30-day aneurysm-related mortality rates were 0.56% (95% confidence interval [CI], 0.00%-2.54%) and 0.00% (95% CI, 0.00%-0.80%), respectively. The pooled aneurysm-related mortality at 1 year of follow-up was 5.25% (95% CI, 0.07%-14.91%). The pooled vessel patency at the end of follow-up was 99.12% (95% CI, 97.73%-99.93%). The pooled reintervention and endoleak rates at the end of follow-up were 10.94% (95% CI, 3.64%-20.67%) and 10.70% (95% CI, 4.45%-18.66%), respectively. The crude spinal cord ischemia and renal failure rates were 0.69% and 1.8%, respectively.

CONCLUSIONS

The results from the present review and meta-analysis have indicated the safety and efficacy of MFM stents for treating challenging aortic pathologic lesions when used as first-line treatment and within the instructions for use. The almost zero pooled 30-day all-cause and aneurysm-related mortality rates combined with the low crude spinal cord ischemia and renal failure rates indicate the use of MFM stents is a good treatment option for complex aortic lesions in the short- and mid-term periods. The lack of long-term follow-up warrants further research concerning the efficacy of the device in the long term.

Multilayer stents affect the final diameter of aortic aneurysms and maintain renal artery patency for a short time in a swine experimental model

OBJECTIVES

We sought to analyze the hemodynamic effects of the multilayer flow-modulated stent (MFMS) in Thoracoabdominal aortic aneurysms (TAAAs).

METHODS

The hemodynamic effects of MFMS were analyzed in aortic thoracoabdominal aneurysms in experimental swine models. We randomly assigned 18 pigs to the stent or control groups and underwent the creation of an artificial bovine pericardium transrenal aneurysm. In the stent group, an MFMS (Cardiatis, Isnes, Belgium) was immediately implanted. After 4 weeks, we evaluated aneurysm sac thrombosis and renal branch patency by angiography, duplex scan, and morphological analysis.

RESULTS

All the renal arteries remained patent after re-evaluation in both groups. Aneurysmal sac thrombosis was absent in the control group, whereas in the stent group it was present in 66.7% of aneurysmal sacs (p=0.061).The mean final aneurysm sac diameter was significantly lower in the stent group (mean estimated reduction, 6.90 mm; p=0.021). The proximal neck diameter decreased significantly in the stent group (mean difference, 2.51 mm; p=0.022) and grew significantly in the control group (mean difference, 3.02 mm; p=0.007). The distal neck diameter increased significantly in the control group (mean difference, 3.24 mm; p=0.017). There were no significant findings regarding distal neck measurements in the stent group.

CONCLUSION

The MFMSs remained patent and did not obstruct the renal arteries within 4 weeks. In the stent group, the device was also associated with a significant decrease in aneurysmal sac diameter and a large proportion (albeit non-significant) of aneurysmal sac thrombosis.

Results of a three-year follow-up after endovascular therapy with multilayer flow modulator in complex thoracoabdominal aortic aneurysm: A case report

OBJECTIVES

Studies on the short-, medium and long-term effects of flow guiding stents are still limited. In this case report, we present three-year follow-up of the multilayer flow modulator stent in a 55-year-old patient with Crawford Type 2 thoracoabdominal aortic aneurysm.

METHODS

A 55-year-old male patient with Crawford Type 2 thoracoabdominal aortic aneurysm had applied to our medical center. The aneurysm involved coeliac truncus and superior mesenteric artery and extended to the renal artery ostia. Multilayer flow modulator stent was successfully placed, and follow-up CT (Computed tomography) angiographic examination images recorded intermittently (36 months).

RESULTS

After three years, it was observed that the left renal artery was thrombosed and the left kidney went to atrophy. Other major vascular branches were observed to be open. During this time, the aneurysm was completely closed with thrombus, but the diameter of the aneurysm continued to increase.

CONCLUSIONS

Multilayer flow modulator stents are safe in complex aortic aneurysms. The device increases the thrombus load in the aortic aneurysm and maintains the flow of the main vascular branches. But re-interventions, dilatation of the aneurysm sac and visceral branch obstructions are still challenging for multilayer flow modulator stents.

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.

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.