The Pulsating Stent Sign in May-Thurner Syndrome.

PURPOSE: To report a case of a patient with May-Thurner syndrome who underwent endovenous stenting and was found to have pulsating arterial compression on the venous stent. REPORT: A 74-year-old man presented with 18 months of progressive right thigh and calf edema. After an extensive work-up, the patient underwent a venogram with intravascular ultrasound (IVUS), revealing compression of the right iliac vein by the external iliac artery and psoas muscle. Following stent deployment, fluoroscopy revealed extrinsic compression by an artery, but IVUS confirmed sufficient stent expansion. On follow-up, there was a significant resolution of right limb edema, and adjacent arterial pulsation/compression was deemed non-significant. CONCLUSION: The choice of venous stents is essential to prevent collapse from extrinsic compression, such as that from an adjacent artery. CLINICAL IMPACT: Carefully choosing venous stents is essential to ensure stent patency in the face of external compression.

Impact of stent compression in patients with non-thrombotic iliac vein lesions on iliac vein blood flow and related symptoms.

OBJECTIVES: To study outcomes in patients with non-thrombotic iliac vein lesions (NIVLs) treated by stents. METHODS: We performed a retrospective study that collected 109 patients from January 2016 to August 2020 diagnosed with symptomatic NIVLs. The patients underwent endovenous stenting using the Wallstents. Clinical severity was assessed using the venous clinical severity score and the Villalta scores. The patency was assessed using duplex ultrasound, while the diameters and the blood flow velocities (BFVs) in the proximal, middle, and distal stented segments were recorded simultaneously. RESULTS: A total of 128 stents were placed in 115 limbs (median age, 61 years), with a mean follow-up of 32 months. At 36 months, the Villalta scores went from 12.17 to 3.64 (p < .001). The VCSS went from 9.41 to 3.31 (p < .001). The mean diameters in the proximal, middle, and distal stented segments were 8.52 ± 2.15 mm, 10.13 ± 1.75 mm, and 10.17 ± 1.69 mm in the first month, while the mean BFVs were 31.17 ± 13.66 cm/s, 31.07 ± 11.90 cm/s, and 36.39 ± 18.41 cm/s, respectively. Repeated-measures analysis in 55 consecutive patients from 1 month to 3 years after procedure revealed a decrease of the stent diameter in the proximal stented segment (p = .004); a stabilization of the stent diameter in the middle (p = .43) or distal (p = .45) stented segment; a steadiness of the BFVs in the proximal (p = .40), middle (p = .93), and distal (p = .25) stented segments; and an improvement in the VCSS (p = .03) and Villalta scores (p = .006). CONCLUSIONS: BFVs in stented segments remained steady and the symptoms in lower extremities improved after surgery, while stent compression was observed in the diameter of the proximal stented segment, with no impact on BFVs or symptoms.

Prophylactic relining for bridging stent compression after thoracoabdominal endovascular aneurysm repair: Myth or reality?

BACKGROUND/OBJECTIVE: Target vessels related complications are one of the most important 'Achille's heel' of complex thoracoabdominal endovascular procedures. The aim of this report is to describe a case of spontaneous bridging stent-graft (BSG) delayed expansion in a patient treated for type III mega-aortic syndrome, associated with aberrant right subclavian artery and independent origin of the two common carotid arteries. METHODS: The patient underwent different surgical procedures (ascending aorta replacement with carotid arteries debranching, bilateral carotid-subclavian bypass with subclavian origins embolization and TEVAR in zone 0, associated with a multibranched thoracoabdominal endograft deployment). Visceral vessels stenting was performed using balloon-expandable BSGs for celiac trunk, superior mesenteric artery and right renal artery, while for the left renal artery a 6 × 60 mm self-expandable BSG was deployed.The first follow-up (FU) by computed tomography angiography (CTA) showed a severe compression of the left renal artery BSG. Considering the challenging access to the directional branches (SAT's debranching and a tightly curve of the steerable sheath inside the branched main body), a conservative treatment was considered, performing a control CTA after 6-months. RESULTS: Six months later, the CTA demonstrated a spontaneous expansion of the BSG, with a two-fold increase in the minimum stent diameter, excluding the need for new reinterventions such as angioplasty or BSG relining. CONCLUSIONS: Directional branch compression is a frequent complication during BEVAR; however, in this case, it spontaneously resolved after 6 months, without the need for secondary adjunctive procedures. Further studies on predictor factors for BSG related adverse events and regarding spontaneous delayed BSGs' expansion mechanisms are needed.

In Vitro Quantification of Gutter Formation and Chimney Graft Compression in Chimney EVAR Stent-Graft Configurations Using Electrocardiography-Gated Computed Tomography.

PURPOSE: To assess the dynamic behavior of chimney grafts during the cardiac cycle. METHODS: Three chimney endovascular aneurysm repair (EVAR) stent-graft configurations (Endurant and Advanta V12, Endurant and Viabahn, and Endurant and BeGraft) were placed in silicone aneurysm models and subjected to physiologic flow. Electrocardiography (ECG)-gated contrast-enhanced computed tomography was used to visualize geometric changes during the cardiac cycle. Endograft and chimney graft surface, gutter volume, chimney graft angulation over the center lumen line, and the D-ratio (the ratio between the lengths of the major and minor axes) were independently assessed by 2 observers at 10 time points in the cardiac cycle. RESULTS: Both gutter volumes and chimney graft geometry changed significantly during the cardiac cycle in all 3 configurations (p<0.001). Gutters and endoleaks were observed in all configurations. The largest gutter volume (232.8 mm3) and change in volume (20.7 mm3) between systole and diastole were observed in the Endurant-Advanta configuration. These values were 2.7- and 3.0-fold higher, respectively, compared to the Endurant-Viabahn configuration and 1.7- and 1.6-fold higher as observed in the Endurant-BeGraft configuration. The Endurant-Viabahn configuration had the highest D-ratio (right, 1.26-1.35; left, 1.33-1.48), while the Endurant-BeGraft configuration had the lowest (right, 1.11-1.17; left, 1.08-1.15). Assessment of the interobserver variability showed a high correlation (intraclass correlation >0.935) between measurements. CONCLUSION: Gutter volumes and stent compression are dynamic phenomena that reshape during the cardiac cycle. Compelling differences were observed during the cardiac cycle in all configurations, with the self-expanding (Endurant-Viabahn) chimney EVAR configurations having smaller gutters and less variation in gutter volume during the cardiac cycle yet more stent compression without affecting the chimney graft surface.

Postoperative CT Evaluation After EVAR: A Comparison of Image Assessment.

PURPOSE: To compare the postoperative computed tomography angiography (CTA) assessment made by vascular surgeons and interventional radiologists after endovascular aneurysm repair (EVAR) at a tertiary vascular clinic to an outside core review facility. METHODS: One hundred patients (mean age 78.7 years, range 88-55; 84 men) with consecutive, elective, routine CTA controls after EVAR were retrospectively studied. Consultant vascular surgeons or radiologists had evaluated all original scans and written the original report. All scans were then reevaluated by an independent core clinic. Findings were classified as vascular or extravascular and stratified as clinically significant or clinically nonsignificant by an independent external reviewer. RESULTS: The number of vascular findings detected by the vascular clinic was 72 vs 69 by the core clinic. The vascular clinic reported more clinically significant findings (primarily stent compression or kinks) as well as endoleaks and their origin. The core clinic reported more pseudoaneurysms (24 vs 12). None of the patients with puncture complications needed reintervention. Interrater analysis of all findings between the 2 clinics showed good agreement when comparing endoleaks overall (without subclassification) and moderate agreement when assessing aneurysm growth. The core clinic reported extravascular findings in 58 patients; 37 of these were classified as clinically significant. The vascular clinic reported extravascular findings in 23 patients; 7 of these were clinically significant. The core clinic also reported 2 cases of suspected malignancies, which had not been reported by the vascular clinic. CONCLUSION: During routine CTA follow-up after EVAR, a significant number of vascular and nonvascular findings are detected. Whereas a highly dedicated vascular clinic identifies most vascular findings regardless of the specialty of the reader, some extravascular findings are missed. However, the frequency of clinically significant findings or findings that might warrant reintervention was low in this study.

An overview of in-stent restenosis in iliofemoral venous stents.

BACKGROUND: Although endovenous stents have been associated with overall low morbidity, they can require reinterventions to correct stent malfunction due to in-stent restenosis (ISR). ISR has often occurred iliofemoral venous stents but has not been well described. It has been reported to develop in >70% of patients who have undergone iliofemoral venous stenting. We sought to provide an overview of ISR in iliofemoral venous stents, including the pathologic, diagnostic, and management considerations and the identification of several areas of potential research in the future. METHODS: A search of reported English-language studies was performed in PubMed and the Cochrane Library. "In-stent restenosis," "vein," "venous," "iliac," and "iliofemoral" were used as keywords. The pertinent reports included in the present review had addressed the pathology, diagnosis, and current management options for ISR. RESULTS: ISR refers to the narrowing of the luminal caliber of the stent owing to the development of stenosis inside the stent itself. ISR should be differentiated from stent compression. Two main types of ISR have been described: soft and hard lesions. These lesions respond differently to angioplasty. Stent inflow and shear stress are important factors in the development of ISR. The treatment options available at present include balloon angioplasty (hyperdilation or isodilation), laser ablation, atherectomy, and Z-stent placement. CONCLUSIONS: Reintervention for ISR should be determined by the presence of residual or recurrent symptoms and not simply by a numeric value obtained from an imaging study. Overall stent occlusion due to ISR is rare, and no role exists for prophylactic angioplasty to treat asymptomatic ISR. The current treatment options for ISR are mostly durable and effective. However, more research is needed on methods to prevent the development of ISR. The role of antiplatelet and anticoagulant agents in the prevention of ISR requires further investigation, with particular attention to unique subset of patients (after thrombosis vs nonthrombotic iliac vein lesions). For high-risk, post-thrombotic patients, anticoagulation can be considered to prevent ISR. The role of triple therapy (anticoagulation and dual antiplatelet therapy) in the prevention of ISR remains unclear.

A unique complication of double barrel Wallstent technique in iliac-caval stenting.

The "double barrel" technique has been a popular option in reconstituting the iliac-caval confluence in bilateral stenting. It has been mostly used with the Wallstent (Boston Scientific, Marlborough, Mass). The technique, although generally trouble-free, has a unique long-term complication. One stent barrel was found to compress the other from a late developing compliance mismatch. The complication is easily missed unless an intravascular ultrasound examination is performed. A cross-fenestration between the two barrels supported by a Z stent might provide clinical relief if the double barrel extension into the vena cava is relatively short in length.

The effect of stent compression on in-stent restenosis and clinical outcomes in iliac vein compression syndrome.

BACKGROUND: To evaluate the effect of stent compression on in-stent restenosis (ISR) and clinical outcomes in patients with iliac vein compression syndrome (IVCS) after iliac vein stenting. METHODS: Fifty patients with IVCS treated with iliac vein stenting (Smart Control, Cordis, USA) between March 2017 and October 2018 were consecutively enrolled in this study. Computed tomography venography (CTV) was performed to assess stent compression and ISR. Based on the degree of stent compression, patients were allocated to a significant stent compression (SSC) group and an insignificant stent compression (ISC) group. The incidence of ISR was analyzed between the SSC and ISC groups. Patients' venous clinical severity scores (VCSSs) and responses to the chronic venous insufficiency questionnaire (CIVIQ) one year after stenting were compared between the two groups to evaluate the clinical improvement of venous insufficiency. RESULTS: In total, 34% of patients had SSC. There were significant differences in the incidence of ISR (52.9% vs. 21.2%, P=0.023), and in each group, there was one case of stent occlusion (5.88% vs. 3.03%, P=0.999). Patients in the SSC group had a higher VCSS score (8.41±5.92 vs. 3.15±2.87, P=0.04) and a lower CIVIQ score (83.35±8.86 vs. 92.21±4.32, P=0.001). CONCLUSIONS: SSC has a significant effect on the incidence of ISR and the clinical outcomes of venous insufficiency. Thus, a dedicated iliac venous stent with sufficient radial resistive force, crush resistance, and outward radial force is needed to prevent the occurrence of stent compression.

Clinical, angiographic and procedural characteristics of longitudinal stent deformation.

Recently, longitudinal stent deformation (LSD) has been reported increasingly. Even though the reported cases included almost all stent designs, most cases were seen in the Element™ stent design (Boston Scientific, Natick, MA, USA). It is considered that stent design, lesion and procedural characteristics play a role in the etiology of LSD. Yet, the effect of LSD on long-term clinical outcomes has not been studied well. Element stents implanted between January 2013 and April 2015 in our hospital were examined retrospectively. Patients were grouped into two according to the presence of LSD, and their clinical, lesion and procedural characteristics were studied. Twenty-four LSD's were detected in 1812 Element stents deployed in 1314 patients (1.83 % of PCI cases and 1.32 % of all Element stents). LMCA lesions (16.7 % vs 1.6 %, p < 0.001), complex lesions (75 % vs 35.1 %, p < 0.001), bifurcation lesions (37.5 % vs 18.3 %, p = 0.017), ostial lesions (33.3 % vs 12.8 %, p = 0.003), using of extra-support guiding catheter (54.2 % vs 22.3 %, p < 0.001) and extra-support guidewire (37.5 % vs 16.2 %, p = 0.005) were found to be more frequent in cases with LSD than in cases without it. In addition, the number of stents, stent inflation pressure and the use of post-dilatation were significantly different between the two groups. Two patients had an adverse event during the follow-up period. LSD is a rarely encountered complication, and is more common in complex lesions such as ostial, bifurcation and LMCA lesions. The use of extra-support guiding catheter, extra-support guidewires and low stent inflation pressure increases the occurrence of LSD. Nevertheless, with increased awareness of LSD and proper treatment, unwanted long-term outcomes can be successfully prevented.

Stent Compression in Iliac Vein Compression Syndrome Associated with Acute Ilio-Femoral Deep Vein Thrombosis.

OBJECTIVE: This study was conducted to evaluate stent compression in iliac vein compression syndrome (IVCS) and to identify its association with stent patency. MATERIALS AND METHODS: Between May 2005 and June 2014, after stent placement for the treatment of IVCS with acute ilio-femoral deep vein thrombosis, follow-up CT venography was performed in 48 patients (35 women, 13 men; age range 23-87 years; median age 56 years). Using follow-up CT venography, the degree of the stent compression was calculated and used to divide patients into two groups. Possible factors associated with stent compression and patency were evaluated. The cumulative degree of stent compression and patency rate were analyzed. RESULTS: All of the stents used were laser-cut nitinol stents. The proportion of limbs showing significant stent compression was 33%. Fifty-six percent of limbs in the significant stent compression group developed stent occlusion. On the other hand, only 9% of limbs in the insignificant stent compression group developed stent occlusion. Significant stent compression was inversely correlated with stent patency (p < 0.001). The median patency period evaluated with Kaplan-Meier analysis was 20.0 months for patients with significant stent compression. Other factors including gender, age, and type of stent were not correlated with stent patency. Significant stent compression occurred most frequently (87.5%) at the upper end of the stent (ilio-caval junction). CONCLUSION: Significant compression of nitinol stents placed in IVCS highly affects stent patency. Therefore, in order to prevent stent compression in IVCS, nitinol stents with higher radial resistive force may be required.

New clinical failure mode triggered by a new coronary stent design.

Longitudinal stent compression (LSC) is a new failure mode not previously observed in coronary stents. This phenomenon occurs when the physician tries to cross the deployed stent with other devices. While this phenomenon has been observed with a number of stent designs, it seems more common with the Element stent. A computational LSC model using finite element analysis was developed. Computational simulations were performed on two representative coronary stents in the current market resembling Element and Endeavor in attempts to quantify individual contribution of the stent design pattern and connector number on LSC. Simulation results show that the connector number plays the most significant role in the development of the LSC issue. The LSC could be easily tripled for the Element stent simply by increasing the connector number from two to three. The stent design pattern plays a secondary role in LSC. The LSC could be improved by up to 30% when the design pattern changes from the offset peak-to-peak design (Element) to the peak-to-peak design (Endeavor). Conclusions obtained from this paper may help clinical stent selection and future stent design optimization to reduce the risk associated with longitudinal stent compression.

Occurrence of longitudinal stent compression before stent deployment: Two case studies.

Several recent reports have described the occurrence of longitudinal stent deformation (LSD, defined as the distortion or shortening of a stent along the longitudinal axis), following its successful deployment. However, few reports have described LSD prior to any stent deployment. This previously unrecognized complication is the result of modifications to stent design. It has been noted that the new-generation stent platforms have a reduced number of connectors, which in turn causes a reduction in longitudinal stent strength. To corroborate previous findings by our lab and others (Vijayvergiya et al, 2013), we describe here two cases of LSD prior to stent deployment that occurred due to crushing of the proximal stent edge by the guide catheter while attempting to withdraw the crimped stent. In addition, we discuss the associated risk factors, such as the length of the stent, and specific management strategies, including technical guidelines and use of fluoroscopic guidance for maneuvering the stent during the procedure.

Longitudinal stent compression of everolimus-eluting stent: A report of 2 cases.

Second generation drug eluting stents (DES) have shown better safety and efficacy in comparison to first generation DES, because of thinner struts, nondurable polymers and coating with better anti-proliferative drugs. The newer DES with cobalt alloy base have demonstrated a greater trackability, deliverability, conformability, flexibility and radio-opacity. However, these thin strut stents have a downside of poor longitudinal axial strength, and therefore get easily deformed/compressed at their end with a slight trauma during exchange of various catheters. We hereby report two cases of "longitudinal stent compression (LSC)" of everolimus-eluting stent, which happened during percutaneous coronary intervention of right coronary artery. Both the cases were successfully managed with non-compliant balloon dilatation. Various reasons for LSC and its management are discussed in the article.