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Background: Thoracoabdominal aneurysms and aortic dissections are a challenge for vascular surgeons. Open surgery, fenestrated or branched endograft, and the chimney technique are not possible in some patients, because of comorbidities or anatomical restrictions. However, the multilayer flow modulator (MFM) can be implanted in some of these patients. In this systematic review, we will describe the experience with the multilayer stent. To augment the limited number of studies available, we will include a cohort of patients from our hospital. Methods: We retrieved data on all consecutive patients treated using the MFM between May 2013 and August 2020. This included patients with type B dissections and thoracoabdominal or thoracic aneurysms who were unfit for open surgery. The systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We included all the studies that used the MFM in the aortic segment. Single-arm meta-analyses were performed using OpenMeta (Brown University, Providence, RI, USA). Results: A total of 37 patients were treated in our hospital during the study period. The technical success was 97.3% and the 30-day mortality was 5.4%. In 40.5% of the included patients, the instructions for use were not followed. Offlabel implantation was associated with a higher aneurysm-related mortality. A total of 12 studies were included in the meta-analysis and the technical success was 97.8%. In 68.5%, the aneurysm sack or false lumen remained perfused, 97% of all the covered side branches remained patent. After a follow-up period of 1 year, five patients in the meta-analysis presented with a ruptured aneurysm. Conclusions: The overall quality of evidence is poor because long-term results are lacking, patients are frequently lost during follow-up and all the studies were non-comparative. Our retrospective study suggests a relatively low incidence of perioperative complications, although there was a high incidence of persistent perfusion in the aneurysm sac (102 of 149 patients). The risk of rupture at the 1-year follow-up was 2.1%. [ABSTRACT FROM AUTHOR]

Purpose: We report the case of an acute type B dissection with high-risk features treated with multilayer stent. Case Report: A 50-year-old female patient presented to the emergency department with an acute type B aortic dissection. Conservative medical treatment did control blood pressure but did not alleviate her dissection symptoms. She was treated endovascularly with multilayer stents extensively covering the whole dissected area. HThe aortic arch side branches, visceral arteries and renal arteries remained patent after treatment. The recovery was uneventful, and she was discharged the day after the intervention. At 6- and 12-month follow-up, the patient remained asymptomatic, the true lumen volume increased and all side branches remained patent. Conclusion: We present a case of the use of a multilayer stent for acute type B aortic dissection. This technique allows to treat the whole dissection with low risk of paraplegia or side branch occlusion. Long-term results of ongoing clinical studies should confirm the place of the multilayer stent as a treatment option for type B aortic dissection. [ABSTRACT FROM AUTHOR]

Background: Thoracoabdominal aneurysms and aortic dissections are a challenge for vascular surgeons. Open surgery, fenestrated or branched endograft, and the chimney technique are not possible in some patients, because of comorbidities or anatomical restrictions. However, the multilayer flow modulator (MFM) can be implanted in some of these patients. In this systematic review, we will describe the experience with the multilayer stent. To augment the limited number of studies available, we will include a cohort of patients from our hospital. Methods: We retrieved data on all consecutive patients treated using the MFM between May 2013 and August 2020. This included patients with type B dissections and thoracoabdominal or thoracic aneurysms who were unfit for open surgery. The systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We included all the studies that used the MFM in the aortic segment. Single-arm meta-analyses were performed using OpenMeta (Brown University, Providence, RI, USA). Results: A total of 37 patients were treated in our hospital during the study period. The technical success was 97.3% and the 30-day mortality was 5.4%. In 40.5% of the included patients, the instructions for use were not followed. Off-label implantation was associated with a higher aneurysm-related mortality. A total of 12 studies were included in the meta-analysis and the technical success was 97.8%. In 68.5%, the aneurysm sack or false lumen remained perfused, 97% of all the covered side branches remained patent. After a follow-up period of 1 year, five patients in the meta-analysis presented with a ruptured aneurysm. Conclusions: The overall quality of evidence is poor because long-term results are lacking, patients are frequently lost during follow-up and all the studies were non-comparative. Our retrospective study suggests a relatively low incidence of perioperative complications, although there was a high incidence of persistent perfusion in the aneurysm sac (102 of 149 patients). The risk of rupture at the 1-year follow-up was 2.1%.

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. [ABSTRACT FROM AUTHOR]

Purpose: To report a single-center series of patients with type B aortic dissection treated with the Multilayer Flow Modulator (MFM). Materials and Methods: Over a 36-month period, 23 patients (median age 53 years; 20 men) with complicated type B aortic dissections (2 acute, 5 subacute, and 16 chronic) were treated with the MFM. Primary endpoints of rupture or dissection-related death, overall mortality, and reintervention were evaluated using the Kaplan-Meier method; estimates for freedom from the endpoints are reported with the 95% confidence interval (CI). Secondary outcomes included technical success, adverse events, and aortic remodeling. Clinical and imaging data were collected preoperatively, directly postoperatively, and annually to 36 months for analysis using computational fluid dynamics (CFD). Results: Initial technical success was 91.3%. The estimates of the endpoints at 12 months were 100% for freedom from rupture or aortic-related death, 95.7% for freedom from overall mortality, and 91.3% for freedom from reintervention. No device-related neurological or systemic complications occurred, and no additional reinterventions were needed during follow-up. A total of 144 branches overstented by the MFM remained patent. Morphologic analysis of the aortic dissection showed progressive true lumen volume increase (75.9%, p<0.001) with concomitant false lumen volume decrease (42.8%, p<0.001); the CFD analyses showed increased laminar flow. Conclusion: In the current series, the MFM provided a safe and feasible treatment option for complicated acute, subacute, and chronic type B aortic dissections, with high technical success, low mortality, and active aortic remodeling. Further studies should elucidate the long-term safety of the MFM and its effectiveness in a larger patient cohort. [ABSTRACT FROM AUTHOR]

Objective To study the feasibility of using two stents (a combination of multilayer stent [MS] and stent graft [SG]) in the treatment of a juxtarenal aortic aneurysm that involves a significant branch artery and to determine the advantages and disadvantages of using SGs upstream and downstream from the aneurysm so as to provide some theoretical guidance for preoperative clinical decision-making in the future. Methods Four ideal geometric models were established for numerical computation: case 1 refers to an aneurysm without the use of stents, case 2 represents the implantation of two MSs in an aneurysm, and case 3 (SG + MS) and case 4 (MS + SG) both involve the treatment of an aneurysm by using a combination of SG and MG. Results The aneurysm pressure is slightly lower and there are more vortices when the SG is implanted (case 3 and case 4). In particular, for case 4, additional vortices appear in the sac and the area of the low-wall shear stress is larger on the aneurysm compared with those of the other three cases. However, the pressure becomes uneven, and a peak pressure region is observed on the wall of the aneurysm, and therefore, the aneurysmal wall will become buckled. In addition, the flux of the renal artery in the four cases is greater than that in the normal case. Conclusion The arrangements in cases 3 and 4 can effectively isolate the aneurysm from circulation, but clinically, it is necessary to avoid such a high-risk situation wherein the SG is positioned downstream of the aneurysm (case 4), even though this leads to improved isolation. [ABSTRACT FROM AUTHOR]

Background: The changes of hemodynamics caused by the implantation of multilayer stent (MS) have significant effects for aneurysm sac.Methods: Comparisons of 3D numerical models with/without a MS in an abdominal aortic aneurysm with a 90° branch vessel were numerically studied from the viewpoint of hemodynamics.Results: The results showed that: (1) The flow fields and Wall Shear Stress (WSS) are changed dramatically after MS implantation. The velocity of the blood flow in aneurysm sac decreases significantly and the regions of low-WSS increase. These help thrombus formation; (2) The pressure in aneurysm slightly decreases and keeps close to the normal level of blood pressure, however the risk of aneurysm enlargement or even rupture still exists; (3) The flux and the velocity in branch artery are reduced by about half after MS implantation. Due to the implantation of MS, the changes in the flow field causes the decrease of pressure/WSS in aneurysm sac and the blood flow in branch vessel.Conclusions: The implantation of MS into abdominal artery results in more low-WSS regions inside aneurysm which induces thrombus formation. The pressure is reduced slightly means the risk of aneurysm rupture exists. [ABSTRACT FROM AUTHOR]

Purpose: To describe the successful management of a symptomatic persistent sciatic artery (PSA) aneurysm using the Multilayer Aneurysm Repair System (MARS). Case Report: A 50-year-old man with history of smoking, hypertension, and hypercholes-terolemia suddenly developed pain in the buttock radiating to the left lower limb, mimicking sciatica. The ~57x54-mm incomplete type PSA aneurysm was treated with two 14x80- and 14x60-mm MARS devices through a surgical left axillary artery access. There were no periprocedural complications. Thirty-day imaging documented patency of the stents and a minor reduction (~47x55 mm) in the aneurysm, with slightly hyperdense content and no signs of perfusion. At 6 months, duplex and computed tomographic angiography showed complete thrombosis of the sac, patency of the multilayer stents, and further aneurysm shrinkage (40x37 mm). Conclusion: The multilayer stent can alter the hemodynamics inside a peripheral aneurysm to promote sac thrombosis and redirect flow to collaterals originating from the sac. [ABSTRACT FROM AUTHOR]

Purpose: To scrutinize registry data on thoracoabdominal repairs performed using the Multilayer Flow Modulator (MFM) outside the indications for use (IFU) and analyze the adverse outcomes. Methods: Of 380 patients from Europe registered in the MFM Global Registry after treatment for thoracoabdominal aortic aneurysm (TAAA) or dissection, 38 (10%) patients (30 men; median age 71 years, range 30-91) treated on a compassionate basis outside the IFU were analyzed. Thirteen patients had chronic Stanford type B dissection with aneurysmal dilatation >6 cm. There were 6 mycotic and 4 saccular aneurysms in addition to 15 primary TAAAs. The mean aneurysm diameter was 7.1 cm. Ten patients presented with rupture, and 23 patients had previous open or thoracic endovascular aortic repair (TEVAR). Results: Although no death, paraplegia, stroke, or renovisceral compromise was documented during the initial hospital stay, technical success was zero. There were 31 (81.6%) cases in which there was failure to land the device in normal aorta. Other violations of the IFU included 12 with inadequate stent overlap and 11 cases involving a small MFM being deployed inside a larger one. Five of the 9 cases in which an undersized device was used resulted in a type I endoleak (failure mode I). During a mean follow-up of 10.0±6.9 months, all-cause mortality was 89.5% (34/38), of which 27 (71.1%) were aneurysm-related deaths. Overall survival, freedom from aneurysm-related death, and rupture-free survival estimates were 17.5%, 25.0%, 31.5%, respectively, at 18 months. There were 8 visceral branch complications; in all, 14 secondary endovascular interventions were required in 11 patients for endoleak (failure modes I and II) or stent foreshortening. No false lumen was completely thrombosed in the dissecting aneurysms. All aneurysms showed a mean sac growth rate of 0.12±0.16 cm/month. Factors having a significance influence on risk of aneurysm-related death included maximum aneurysm diameter (p=0.025, HR 1.37, 95% CI 1.04to1.82), previous TEVAR (p=0.03, HR 2.44, 95% CI 1.10 to 2.08), and inadequate overlap between MFM devices (p<0.002, HR 4.02, 95% CI 1.70 to 9.49). Conclusion: There are clinical scenarios in which the MFM does not perform well. The MFM is not a solution for patients living on borrowed time and should not be used indiscriminately in patients in whom other modalities of aortic repair are not feasible. Its use must adhere to the IFU, and robust clinical data are required before constructing a randomized controlled trial. [ABSTRACT FROM AUTHOR]

Purpose: To report the use of multilayer uncovered stent to treat primary infected juxtarenal aortic aneurysm. Case Report: A 50-year-old man was admitted to hospital for rapid onset of intractable abdominal pain and high fever. Computed tomographic scan showed 2 juxtarenal saccular aneurysms of abdominal aorta with morphologic and clinical changes compatible with infectious etiology. Patient was treated with multilayer flow-modulating stent. Follow-up imaging showed persistent aneurysm exclusion and continuous aneurysm shrinkage of the sac until complete regression to a normal aortic configuration was seen at 1 year. During follow-up (24 months), patient continued to do well, and there was no recurrence of infection. Conclusion: Multilayer stent appeared to be an acceptable treatment option for primary infected juxtarenal aortic aneurysms. Aneurysmal sac completely disappeared and visceral branches remained patent at 2-year follow-up. However, longer follow-up is necessary to evaluate the long-term patency of involved visceral arteries. [ABSTRACT FROM AUTHOR]

Purpose: The present study was performed to analyze the midterm results (five consecutive patients, 2-year follow-up) of the endovascular management of visceral artery aneurysms using the Cardiatis Multilayer Flow Modulator (CMFM) (Cardiatis, Isnes, Belgium), a self-expandable stent. Materials and Methods: From August 2009 to January 2011, we implanted five CMFMs in five patients (all men; mean age 73 years) to treat two common hepatic artery aneurysms, one celiac trunk aneurysm, one splenic artery aneurysm, and one superior mesenteric artery aneurysm (diameter 25-81 mm). The primary end point was technical success. The secondary end point was stent patency, absence of aneurysm rupture or reperfusion, and shrinking of the sac at 6-, 12-, and 24-month follow-up using computed tomography angiography. Follow-up ranged from 24 to 48 months (mean 31.2). Results: Technical success was achieved in all patients. Complete exclusion of the aneurysm with sac shrinking was achieved in two patients. Two stents became occluded at 6- and 24-month follow-up, respectively; both patients were asymptomatic and were not retreated. One patient developed sac reperfusion due to incomplete aneurysm exclusion. Conclusion: Long-term results in a wider population are needed to validate the effectiveness of the CMFM. [ABSTRACT FROM AUTHOR]

Purpose: To present a series of para-anastomotic iliac artery aneurysms treated with flow- diverting stents. Case Reports: Three patients (2 men, 1 woman; ages 70, 73, and 78 years) with previous open aortoiliac reconstructions received a 12-mm-diameter Cardiatis Multilayer Stent to treat 4 para-anastomotic iliac artery aneurysms in an attempt to preserve their ipsilateral hypogastric arterias. After 1-year follow-up, all aneurysms were successfully excluded, with complete sac thrombosis in three and partial thrombosis in one. The diameter of the aneurysm was reduced in all by a median 6 mm. At 1 year, patency of the hypogastric artery was maintained in only the patient with partial sac thrombosis. No patient developed buttock claudication. Conclusion: The use of flow-diverting stents for para-anastomotic iliac artery aneurysms resulted in reduction of iliac aneurysm diameter. However, intended patency of the ipsilateral hypogastric artery was not always observed. The feasibility of the technique has therefore not been shown for this specific indication. [ABSTRACT FROM AUTHOR]

Purpose: This study was designed to evaluate retrospectively the results of complex iliac artery aneurysm (IAA) exclusion using the Cardiatis-Multilayer-Stent. Methods: Between October 2010 and August 2012, ten IAAs were treated in eight males (mean age 75 (59-91) years) using the Multilayer Stent. All IAA exceeded a diameter of 3 cm or were symptomatic. Follow-up (FU) examinations included CT or MR angiography, sonography, and clinical assessment up to 2 years. Results: Primary stent placement was technically successful in eight of ten cases. In two cases, severe stent retraction during deployment necessitated placement of an additional stent. Immediately after stent placement, a marked reduction of flow within the sac was observed in all cases (peri-interventional mortality 0 %). During FU, there were two thrombotic stent occlusions, making reintervention necessary (primary patency rate 80 %, secondary patency 100 %). Four IAA were completely occluded at FU, whereas the original vessel and covered branches ( n = 8) were patent. In four IAA, there was still residual perfusion. In one patient, IAA diameter decreased slightly, while it remained constant in seven (mean imaging FU 195 (range 1-695) days). There were no adverse events on clinical FU (mean FU 467 (range 101-695) days). Conclusions: Other studies showed the Cardiatis-Multilayer-Stent to be a technically relatively simple treatment option for complex IAA with inadequate landing zones, especially in patients with multiple comorbidities to avoid ipsilateral IIA obstruction. However, in our series complication rate was high. Incomplete sac exclusion, stent-shortening, and thrombotic occlusion can complicate treatment, making meticulous patient selection necessary. Close imaging surveillance is mandatory especially in the early postinterventional period. [ABSTRACT FROM AUTHOR]

Purpose: To report midterm failure of tandem peripheral multilayer stents used to treat a common hepatic artery aneurysm (HAA) that had a good early result. Case Report: A 71-year-old man with multiple comorbidities had a 3.4-cm HAA treated with 2 Cardiatis peripheral multilayer stents (8x100 and 9x60 mm) that overlapped by 3 cm. At the 12-month follow-up, the stents were patent, with signs of collateral patency and full thrombosis of the aneurysm sac without expansion. At the 18-month visit, the sac had expanded to 4.5 cm without signs of revascularization, but there was an initial stent dislocation; a wait and watch approach was elected. On the 24-month imaging, the HAA had enlarged to 6 cm, with disconnection of the 2 stents. A new multilayer stent (9x100 ram) was positioned to "bridge" the gap; however, the proximal part of the new stent did not correctly expand despite multiple attempts to overcome the infolding. The 3 stents became completely thrombosed, but thanks to rich mesenteric collaterals, perfusion of the proper hepatic artery was adequate. Conclusion: The multilayer peripheral stent appears to be an alternative for the treatment of visceral aneurysms in patients with a high surgical risk, but it is not a conventional stent. There are unknowns about its function, behavior, and application. Therefore, more experience is needed to validate the effectiveness of the multilayer stent. [ABSTRACT FROM AUTHOR]

Purpose: To report 1-year results from the first subgroup of patients treated with the Multilayer Flow Modulator (MFM) stent for aortic aneurysm and dissection. Methods: Up to December 2012, 243 patients have been treated worldwide for aortic aneurysm and dissection with the Cardiatis MFM under the established indications for use. This retrospective review encompasses the first 55 of these patients (41 men; mean age 64.5±18 years), who were treated on a compassionate basis in 11 countries. There were 31 thoracoabdominal aortic aneurysms (8 Crawford type I, 3 type II, 9 type Ill, and 11 type IV), 7 arch aneurysms, 3 infrarenal abdominal aortic aneurysms, 8 suprarenal aortic aneurysms, and 6 type B dissections. Mean aneurysm diameter was 6.04 ±1.66 cm, and the mean length was 11.58 ±7.62 cm. The primary endpoint at 1 year was a composite of rupture and aneurysm-related death. The secondary endpoints were all-cause mortality, visceral branch occlusion, adverse events (i.e., stroke and paraplegia), and reintervention. Results: Technical success was 98.2%; there was no paraplegia or perioperative visceral or renal insult. The mean number of side branches covered was 3.7±1.3 per case (range 0-6); 108 stents were deployed (range 1-5). At 1 year, aneurysm-related survival was 93.7%, all-cause survival was 84.8%, intervention-free survival was 92.4%, and all of the 202 side branches were patent. There were no stent fractures. At 6 months, the mean rate of sac volume increase was 0.36% per month, resulting in a mean volume increase of 2.14%. At 12 months, the rate of increase had slowed to 0.28% per month, resulting in a total average increase in sac volume of 3.26%. The ratio of thrombus to total volume stayed almost constant over the 12 months at 0.48, while the ratio of flow to total volume fell from 0.21 to 0.12 at 12 months. Conclusion: MFM implantation instigates a process of aortic remodeling involving initial thrombus deposition, which slowed between 6 and 12 months. Increasing sac size did not herald rupture, and the MFM was not associated with loss of native side branches. With physiological modulation of the aneurysm, the MFM offers promise for resolution of complex thoracoabdominal pathology with off-the-shelf availability, but this disruptive technology requires further development and technical refinement. Long-term follow-up of the registry patients is mandatory before establishing a randomized controlled study. [ABSTRACT FROM AUTHOR]

Purpose: To present a preliminary experience using a multilayer flow-modulating stent for trans/infragenicular popliteal endovascular aneurysm repair. Methods: Five men (mean age 76 years, range 62-86) with 6 popliteal artery aneurysms (PAAs) measuring 22 to 39 mm in diameter (mean 30) underwent endovascular repair using the Cardiatis Multilayer Aneurysm Repair System (MARS) between June and August 2011. Radiological assessments post procedure using duplex ultrasonography and biplanar knee radiographs (additional contrast studies as necessary) sought evidence of aneurysm exclusion, graft patency, and preservation of branches and runoff vessels. Results: Technical success was achieved in each case. There was one symptomatic stent occlusion requiring thrombectomy at 4 days, with reocclusion, and one leak via the stent struts into the sac with no branch outflow identified. Two further symptomatic stent occlusions were identified within a 6-week follow-up period, totaling 3 occlusions among the 6 devices deployed. Conclusion: No firm conclusion can be reached on the efficacy of the MARS in PAAs due to the inherent limitations of this small series, although a 50% thrombosis rate is a poor outcome. The risk of early thrombosis in flow-modulating stents deployed in the popliteal artery exists, as it does with earlier generation stent-grafts. Larger prospective trials and the influence of more aggressive antithrombotic/anticoagulant therapy should be considered to enable accurate evaluation of this device in popliteal artery aneurysms. [ABSTRACT FROM AUTHOR]

Combined abdominal aortic aneurysm (AAA) and iliac artery aneurysm (IAA) is a common condition. The recently approved Cardiatis Multilayer stent (Cardiatis, Isnes, Belgium) is an innovative stent system for peripheral aneurysm management that has been applied in several clinical cases. After deployment, the unique stent design reduces mean velocity and vorticity within the aneurysm sac, causing thrombus formation and thus exclusion of the aneurysm while the vessels branching from the aneurysm remain patent. We describe a case of combined AAA and IAA with successful endovascular aneurysm repair of the AAA and treatment of the internal iliac artery with the Cardiatis Multilayer stent at 12 months of follow-up. [ABSTRACT FROM PUBLISHER]

The Cardiatis multilayer stent (Cardiatis, Isnes, Belgium) is a cobalt, self-expandable bare stent made of two interconnected layers without any covering that allows a pressure decrease and thrombus formation into an aneurysmal sac, while improving laminar flow in the main artery and surrounding vital branches. We report a case of an anastomotic iliac pseudoaneurysm successfully treated with the deployment of a Cardiatis multilayer stent. [ABSTRACT FROM AUTHOR]

Purpose: To describe a case of multiple thoracoabdominal aneurysms of tuberculous origin treated in an endovascular procedure with the Multilayer stent. Case Report: A 16-year-old girl had been treated 4 years previously for a ruptured abdominal aortic aneurysm of tuberculous origin. Due to the presence of 4 rapidly evolving saccular aneurysms of the descending thoracic aorta and a fusiform aneurysm of the suprarenal aorta, an endovascular solution was chosen after the patient refused open surgery. Three uncovered Multilayer stents (16×40, 16×80, and 16×80 mm) were successively implanted with a 1-cm overlap from the left subclavian artery to cover the entire aneurysmal segment of the thoracoabdominal aorta to above the renal arteries. At 18 months, serial imaging studies have shown disappearance of some aneurysms and regression of others. Conclusion: In this young patient, the endovascular treatment of a thoracoabdominal aneurysm with an uncovered stent made it possible to stabilize the aneurysm process without exposing the patient to the high morbidity and mortality of open surgery. [ABSTRACT FROM AUTHOR]