Coaxial Placement of Balloon-Expandable and Self-Expanding Stents: Impact on Crush Resistance and Luminal Recovery in a Benchtop Model.

During endovascular interventions, coaxial deployment of stents may be required to preserve luminal gain. This study characterized in vitro the effect on crush resistance and postcompression recovery when 316L stainless steel balloon-expandable (BE) and laser-cut nitinol self-expanding (SE) venous stents were deployed coaxially. Various stent configurations were parallel-plate compressed from a fully expanded state to 50% diameter reduction (Criterion, Model 42; MTS, Eden Prairie, Minnesota) in a 37 °C ± 1 water bath. Coaxial deployments of SE stent inside BE stent and BE stent inside SE stent demonstrated higher crush resistances compared with each stent individually or their mathematical summation (analysis of variance P < .0001; pairwise comparison P < .01). The configuration of SE stent inside BE stent showed higher postcompression luminal recovery at 48.7% compared with that of BE stent inside SE stent at 27.5% (P = .0001). Coaxial deployment of SE stent inside BE stent may improve crush resistance and luminal recovery after compression in the appropriate clinical context.

Classification System for Inferior Vena Cava (IVC) Appearance Following Percutaneous IVC Filter Retrieval.

OBJECTIVE: There is no classification system for describing inferior vena cava (IVC) injuries. The objective of this study was to develop a standardized grading system for venographic appearance of the IVC following percutaneous IVC filter retrieval. METHODS: A classification system for the appearance of the IVC on cavograms following percutaneous IVC filter removal was developed consisting of two grading elements; luminal characteristics and extravasation. Luminal narrowing from 0% up to 50% from any cause is grade 1; narrowing between 50 and 99% is grade 2; occlusion is grade 3; and avulsion is grade 4. Absence of extravasation is grade A, contained extravasation is grade B, and free extravasation is grade C. This system was then applied retrospectively to pre- and post-IVC filter retrieval cavograms performed at a single institution from October 2004 through February 2019. RESULTS: 546 retrieval attempts were identified with 509 (93.2%) filters successfully retrieved. 449 cases (88.2%) had both pre-retrieval and post-retrieval imaging appropriate for application of the proposed classification system. Inter-rater reliability was 0.972 for luminal characteristics, 0.967 for extravasation, and 0.969 overall. Consensus grading demonstrated a distribution of 97.3% grade 1, 1.3% grade 2, 1.3% grade 3, and 0.0% grade 4 for post-retrieval luminal characteristics. For extravasation classification, 96.4% of the cases were classified as grade A, 2.7% grade B, and 0.9% grade C. CONCLUSION: A classification system was developed for describing IVC appearance after IVC filter retrieval, and retrospectively validated using a single center dataset.

Impact of Postthrombotic Vein Wall Biomechanics on Luminal Flow during Venous Angioplasty and Stent Placement: Computational Modeling Results.

This study characterized the impact of vein wall biomechanics on inflow diameter and luminal flow during venous angioplasty and stent placement, using postthrombotic and healthy biomechanical properties from an ovine venous stenosis and thrombosis model. Finite element analysis demonstrated more pronounced inflow channel narrowing in the postthrombotic vein compared with the healthy control vein during angioplasty and stent placement (relative inflow diameter reduction of 42% versus 13%, P < .0001). Computational fluid dynamics modeling showed increased relative areas of low wall shear rate in the postthrombotic vein compared with the normal vein (0.46 vs 0.24 for shear rate < 50 s-1; 0.13 vs 0.07 for shear rate < 15 s-1; P < .05), with flow stagnation and recirculation. Since inflow narrowing and low wall shear rate are associated with in-stent restenosis and reintervention, these computational results based on experimentally obtained biomechanical values highlight the significance of postthrombotic venous properties in optimizing venous intervention outcomes.

Endovascular Venous Stenosis and Thrombosis Large Animal Model: Angiographic, Histological, and Biomechanical Characterizations.

PURPOSE: To characterize an ovine endovascular radiofrequency (RF) ablation-based venous stenosis and thrombosis model for studying venous biomechanics and response to intervention. MATERIALS AND METHODS: Unilateral short-segment (n = 2) or long-segment (n = 6) iliac vein stenoses were created in 8 adult sheep using an endovenous RF ablation technique. Angiographic assessment was performed at baseline, immediately after venous stenosis creation, and after 2-week (n = 6) or 3-month (n = 2) survival. Stenosed iliac veins and the contralateral healthy controls were harvested for histological and biomechanical assessment. RESULTS: At follow-up, the short-segment RF ablation group showed stable stenosis without occlusion. The long-segment group showed complete venous occlusion/thrombosis with the formation of collateral veins. Stenosed veins showed significant wall thickening (0.28 vs 0.16 mm, P = .0175) and confluent collagen deposition compared with the healthy controls. Subacute nonadherent thrombi were apparent at 2 weeks, which were replaced by fibrous luminal obliteration with channels of recanalization at 3 months. Stenosed veins demonstrated increased longitudinal stiffness (448.5 ± 5.4 vs 314.6 ± 1.5 kPa, P < .0001) and decreased circumferential stiffness (140.8 ± 2.6 vs 246.0 ± 1.6 kPa, P < .0001) compared with the healthy controls. CONCLUSION: Endovenous RF ablation is a reliable technique for creating venous stenosis and thrombosis in a large animal model with histological and biomechanical attributes similar to those seen in humans. This platform can facilitate understanding of venous biomechanics and testing of venous-specific devices and interventions.

Aortic Dissection: Branched, Fenestrated, and Parallel Aortic Stent Grafts in the Ascending Aorta and Arch.

Open surgical repair of dissections and post-dissection degenerative aneurysms involving the ascending thoracic aorta and aortic arch, whether in the acute or post-repair state, is associated with high rates of morbidity and mortality. Recent advancements in minimally invasive endovascular techniques have expanded the role of thoracic endovascular aortic repair (TEVAR) for dissections and dissection-related arch pathologies. Image-guided endovascular techniques, such as in situ fenestrated grafts, chimney and/or periscope grafts, along with newly developed commercially available branched aortic devices, have allowed for an increasing number of high-risk operative candidates to undergo definitive repair of aortic arch pathology who otherwise would have been destined for non-operative management. This paper reviews the data, pre-procedural planning, and technical considerations for complex TEVAR techniques for ascending and aortic arch dissections and dissection-related aneurysms.

Lateral tilt during IVC filter placement does not predict the need for advanced filter retrieval techniques.

PURPOSE: We aimed to determine if lateral inferior vena cava (IVC) filter tilt at placement predicts the need for subsequent advanced retrieval techniques. METHODS: A retrospective chart review was performed of all Gunther Tulip IVC filter placements with subsequent retrievals between February 2015 and October 2017. Chart and imaging review was performed for patient, filter placement, and filter retrieval demographics/characteristics. Degree of agreement between two measurement sets was evaluated with the intraclass correlation (ICC) analysis. Categorical variables were compared with chi-square or Fisher exact test, as appropriate. Kendall rank correlation was used to measure correlation between categorical variables. RESULTS: There was poor agreement between filter tilt angle at the time of placement and retrieval (ICC coefficient, 0.54). Mean difference ± standard deviation between tilt angle at the time of placement and retrieval was 4.6°±4.3° (p = 0.35). Among patient- or procedure-related factors, a common femoral vein access on placement (regression coefficient, -2.90; p = 0.039) was associated with a lower difference between placement and retrieval filter tilt angles compared to internal jugular vein access. Higher filter tilt angle measured at the time of retrieval (OR: 1.19, p = 0.025), hook embedment (OR: 77.3, p < 0.001), and a longer dwell time (OR: 1.25, p = 0.002) were associated with the need for advanced retrieval techniques. However, in univariate and multivariate analysis filter tilt angle at the time of placement was not associated with the subsequent need for advanced retrieval technique (p = 0.16). CONCLUSION: Lateral tilt at the time of placement is poorly associated with lateral tilt at the time of retrieval and does not correlate with the need for advanced retrieval technique.

Venous Biomechanics of Angioplasty and Stent Placement: Implications of the Poisson Effect.

PURPOSE: To characterize the Poisson effect in response to angioplasty and stent placement in veins and identify potential implications for guiding future venous-specific device design. MATERIALS AND METHODS: In vivo angioplasty and stent placement were performed in 3 adult swine by using an established venous stenosis model. Iron particle endothelium labeling was performed for real-time fluoroscopic tracking of the vessel wall during intervention. A finite-element computational model of a vessel was created with ADINA software (version 9.5) with arterial and venous biomechanical properties obtained from the literature to compare the response to radial expansion. RESULTS: In vivo angioplasty and stent placement in a venous stenosis animal model with iron particle endothelium labeling demonstrated longitudinal foreshortening that correlated with distance from the center of the balloon (R2 = 0.87) as well as adjacent segment narrowing that correlated with the increase in diameter of the treated stenotic segment (R2 = 0.89). Finite-element computational analysis demonstrated increased Poisson effect in veins relative to arteries (linear regression coefficient slope comparison, arterial slope 0.033, R2 = 0.9789; venous slope 0.204, R2 = 0.9975; P < .0001) as a result of greater longitudinal Young modulus in veins compared with arteries. CONCLUSIONS: Clinically observed adjacent segment narrowing during venous angioplasty and stent placement is a result of the Poisson effect, with redistribution of radially applied force to the longitudinal direction. The Poisson effect is increased in veins relative to arteries as a result of unique venous biomechanical properties, which may be relevant to consider in the design of future venous interventional devices.

Management of Phlegmasia Cerulea Dolens with Percutaneous Mechanical Thrombectomy.

Advanced cases of phlegmasia cerulea dolens (PCD) with absent pedal pulses, sensory/motor deficits, and/or venous gangrene likely require more rapid restoration of flow compared to cases without these factors to prevent progression and associated morbidity/mortality. We present a case of PCD with absent pedal pulses and sensory deficit managed successfully with emergent percutaneous mechanical thrombectomy using Inari ClotTriever (Inari Medical, Irvine, CA) with immediate clinical resolution, including restoration of pedal pulses ~ 45 min after thrombectomy. Percutaneous mechanical thrombectomy with the ClotTriever device has the ability to immediately restore venous flow reversing the pathophysiology of PCD in a short time period similar to surgical embolectomy and may be an alternative treatment strategy in patients with phlegmasia cerulea dolens of high severity.

Correction to: Yttrium-90 Radioembolization for BCLC Stage C Hepatocellular Carcinoma Comparing Child-Pugh A Versus B7 Patients: Are the Outcomes Equivalent?

The name of one of the co-authors was slightly misspelled. Kristian Enestvedt is listed currently as "Kristian K. Enestvedt" and should be listed instead as "C. Kristian Enestvedt."

Yttrium-90 Radioembolization for BCLC Stage C Hepatocellular Carcinoma Comparing Child-Pugh A Versus B7 Patients: Are the Outcomes Equivalent?

OBJECTIVE: To evaluate yttrium-90 (Y90) radioembolization outcomes across Child-Pugh scores in patients with advanced hepatocellular carcinoma (HCC). MATERIALS AND METHODS: From April 2005 to December 2018, 106 consecutive patients with BCLC Stage C HCC who underwent Y90 radioembolization were retrospectively analyzed. Exclusion criteria included additional malignancy (n = 7), death unrelated to liver disease (n = 2), metastases (n = 2), or lack of follow-up data (n = 4). Ninety-one patients were analyzed. Overall survival (OS) was calculated using the Kaplan-Meier method and compared between groups with the log-rank test. Cox regression modeling was used to evaluate the prognostic factors for survival. RESULTS: Mean age was 63 years and 85.7% were male. HCV infection was the most common etiology of liver disease (58.2%). Sixty-four (70.3%) patients were Child-Pugh A, 19 (20.9%) patients were B7, and eight (8.8%) patients were B8-9. Median OS after radioembolization was 20.2 [95% confidence interval (CI) 13.0-27.4], 6.0 (95% CI 4.4-7.6), and 5.5 (95% CI 2.5-8.5) months for Child-Pugh A, B7, and B8/9 groups, respectively (P < 0.001 for B7 vs. A; P = 0.537 for B7 vs. B8/9). The multivariable Cox regression analysis showed that Eastern Cooperative Oncology Group (ECOG) score (P < 0.001), Child-Pugh class (P = 0.005), tumor morphology pattern (P = 0.012), and Y90 delivery location (P = 0.020) were significant independent predictors of overall survival. CONCLUSIONS: Outcomes from Y90 for BCLC C HCC for Child-Pugh B7 patients were equivalent to B8/9 patients and significantly worse compared to Child-Pugh A patients. Although further research is warranted, these results suggest continued cautious patient selection for radioembolization in advanced HCC.

Evaluation and Management of Intermediate and High-Risk Pulmonary Embolism.

OBJECTIVE. The evidence regarding pulmonary embolism treatment has greatly advanced over the past 10 years, particularly in patients with right ventricular dysfunction or hemodynamic instability. Treatment options include systemic anticoagulation, systemic thrombolysis, catheter-assisted thrombus removal (mechanical with or without catheter-directed thrombolysis), and surgical embolectomy. CONCLUSION. This article will review the data available for treatment options and summarize the evidence-based guidelines on treatment of intermediate- or high-risk pulmonary embolism.

Palmar Warming for Radial Artery Vasodilation to Facilitate Transradial Access: A Randomized Controlled Trial.

PURPOSE: To investigate the efficacy of palmar warming to induce radial artery vasodilation. MATERIALS AND METHODS: After informed consent was obtained, healthy volunteers (n = 45) were randomized 2:1 in palmar warming and control groups, respectively, for this prospective, randomized, single-blind clinical trial (NCT03620383). The palmar warming group was given a warm, commercially available, air-activated heat pack (Kobayashi Consumer Products LLC, Dalton, Georgia) to hold in the left hand for palmar warming. The control group was given a deactivated version of the same heat pack. Left radial artery cross-sectional area (CSA) measurements were obtained at baseline and in 5-minute intervals up to 20 minutes in both groups. Differences in the trends of changes in the radial artery CSA between palmar warming and control groups were examined with the age- and sex-adjusted repeated measure analysis of variance. Propensity score-matched treatment effect analysis was conducted to quantify the effect of heat on radial artery CSA. RESULTS: The palmar warming group and the control group were significantly different in terms of subject sex (males/females: 7/23 and 10/5, respectively; P = .005) and baseline CSA (2.5±0.2 mm2 vs 3.2±0.3 mm2, respectively; P = .014). Radial artery CSA showed an increasing trend over time in the palmar warming group compared to a stable trend over time in the control group (P < .0001). Propensity score-matched comparison showed a 43.9% increase (95% confidence interval: 34.1%-53.8%) in CSA in the palmar warming group compared to the control group (P < .0001). CONCLUSIONS: The palmar warming technique is effective at dilating the radial artery and may be a beneficial technique to facilitate transradial access.

Early Venous Stent Failure Predicted by Platelet Count and Neutrophil/Lymphocyte Ratio.

BACKGROUND: Inflammation and platelet activation have been shown to be involved in acute thromobogenicity following venous occlusive conditions. The aim of this study was to identify the association of baseline platelet count and neutrophil/lymphocyte ratio (NLR) with venous stent failure. Methods and Results: Patients who underwent technically successful iliocaval venous stent placement with available baseline complete blood count and follow-up stent patency data were selected (n=50). Stent failure was defined as >50% stenosis or occlusion at follow-up angiography, contrast-enhanced CT, MRI or duplex US. Median patient age was 49.5 years (range, 13-76 years), and 62% were female. Median follow-up time was 10.2 months (range, 0.1-76.4 months). Stent failure occurred in 13 patients (26%) after a median of 1.2 months (range, 1 day-76.4 months). On multivariable-adjusted Cox modeling, baseline platelets (HR, 2.28; P=0.004) and WBC count (HR, 2.03; P=0.013) were significantly associated with stent failure on follow-up; neutrophils (HR, 16.10; P=0.050); and NLR (HR, 12.19; P=0.050) had borderline significance. Compared with patients without stent failure, those with early, but not late, stent failure had higher baseline platelets (P=0.031) and neutrophils (P=0.025), and NLR (P=0.026). CONCLUSIONS: Baseline platelet count and NLR are associated with early but not late failure of iliocaval venous stents. This suggests different pathophysiologic mechanisms and a role for both platelet activation and inflammatory mechanisms in early rather than late stent thrombosis. Future research is needed to better explain this novel finding.

Advanced Techniques in Thoracic Endovascular Aortic Repair: Chimneys/Periscopes, Fenestrated Endografts, and Branched Devices.

Thoracic endovascular aortic repair (TEVAR) is a rapidly growing and improving technique for the management of thoracic aortic aneurysms, dissections, and traumatic aortic injury. These disease processes were previously treated exclusively by surgery, but TEVAR has substantially improved patient outcomes including reduced mortality, reduced paraplegia rate, and shorter hospital and/or intensive care unit stay compared to open surgery. TEVAR was initially isolated to the descending thoracic aorta, but the advent of advanced techniques has extended the scope to well beyond the left subclavian artery and into Zone 0. Recent techniques include chimney grafts, periscope grafts, in situ fenestrations, and physician modified grafts. In addition, commercial branched aortic devices are currently on trial and will likely vastly extend the off-the-shelf capabilities of TEVAR for aortic arch disease. This paper reviews the data, concepts, and technical aspects of current advanced TEVAR techniques, as well as ongoing clinical trials for thoracic branched aortic devices.

Iliac Vein Stent Placement: Acute Venographic Changes and Relevance to Venous Biomechanics.

PURPOSE: To describe acute venographic changes of external iliac vein (EIV) after ipsilateral common iliac vein (CIV) stent placement. MATERIALS AND METHODS: Retrospective review was performed of 17 cases with placement of a single CIV stent. Central CIV stent diameter and minimal ipsilateral EIV diameter were measured on venogram; vein diameter was measured at the same 2 anatomic locations on venogram obtained before intervention. Relative CIV diameter increase was defined as the ratio of change in central CIV diameter after stent placement to CIV diameter before intervention. Relative EIV diameter reduction was defined as the ratio of change in diameter of EIV after stent deployment in CIV to EIV diameter before intervention. Diameters before and after intervention were compared using a 2-tailed, paired sample t test. Pearson coefficient was calculated for correlations. RESULTS: There was a significant reduction of EIV diameter after ipsilateral CIV stent placement compared with before stent placement (mean 9.3 mm ± 3.1 vs 11.9 mm ± 3.8; P < .01); mean decrease in EIV diameter was 21.7% ± 15.8. There was a correlation between relative CIV diameter increase and relative EIV diameter reduction (r = .8917). CONCLUSIONS: Significant venographic narrowing of the EIV occurs after placement of an adjacent CIV stent, and the degree of narrowing is associated with the relative increase in CIV diameter. These findings may be explained by the inherent anisotropic elasticity of veins. Further study is warranted to guide future venous interventions.

Endovascular Treatment of Concurrent Bilateral Common and Internal Iliac Artery Aneurysms with Preserved Pelvic Circulation: Bilateral Iliac Branch Devices with Opposing Single Division Internal Iliac Artery Sparing.

An 83-year-old man with bilateral common iliac artery aneurysms (right, 3.0 cm; left, 2.7 cm), bilateral internal iliac artery aneurysms (right, 3.4 cm; left, 2.6 cm), and an abdominal aortic aneurysm (3.8 cm) was treated with an aortobi-iliac stent graft and bilateral iliac branch devices. The internal iliac components were extended into opposing posterior (left) and anterior (right) divisions of the internal iliac artery using stent grafts. Computed tomography angiography demonstrated that all aneurysms decreased or were stable in size with patent stent grafts at 1 month. The patient was asymptomatic without complications of pelvic ischemia at the last clinical follow-up at 6 months.

Techniques and Devices for Catheter-Directed Therapy in Pulmonary Embolism.

The clinical presentation of a patient with acute pulmonary embolism (PE) can be classified into 3 categories: low-risk, submassive (presence of right heart strain), and massive (hemodynamic compromise). Massive PE is associated with high morbidity or mortality and typically treated with systemic intravenous thrombolysis. Over the last 2 decades, however, catheter-directed techniques have become an increasingly popular treatment modality for patients with a contraindication to systemic thrombolysis or without clinical improvement after systemic thrombolysis. Furthermore, endovascular treatment for patients with submassive PE has been of great interest due to the significantly increased mortality associated with right heart strain, and prospective clinical trials have demonstrated catheter-directed thrombolysis to decrease right heart strain earlier than systemic anticoagulation alone. This article describes available devices and endovascular techniques used to treat patients with massive and submassive acute PE.

Continuous Aspiration Mechanical Thrombectomy for the Management of Submassive Pulmonary Embolism: A Single-Center Experience.

The Indigo Mechanical Thrombectomy System (Penumbra, Inc, Alameda, California) was used to treat 6 patients with submassive pulmonary embolism (PE) and a contraindication to thrombolysis. Systolic pulmonary artery pressure (58.2 mm Hg vs 43.0 mm Hg, P < .05), right ventricular/left ventricular ratio (1.7 vs 1.1, P < .05), Miller index (15.0 vs 9.8, P < 0.01), and CT obstructive index (60.4% vs 47.0%, P < .01) were significantly reduced after mechanical thrombectomy. There were no procedural or periprocedural complications. Continuous aspiration mechanical thrombectomy is a feasible and promising technique for management of submassive PE to decrease thrombus burden and reduce right heart strain.

Gastroduodenal artery coiling to curb upper gastrointestinal bleeding.

BACKGROUND: Peptic ulcers in pediatric populations are uncommon and can present with upper gastrointestinal bleeding and shock on presentation. An endoscopy is done initially to identify bleeding source. However, definitive treatment is achieved with angiography. The use of coiling is effective in achieving hemorrhagic control in duodenal ulcers or gastric ulcers, particularly in adults. However, the use in pediatric populations is unknown. We present a case of peptic ulcer disease treated with a gastroduodenal artery coil in a pediatric patient that has never been reported in the literature. CASE PRESENTATION: A 15-year-old male with a five-year history of peptic ulcer disease was admitted with an upper gastrointestinal bleed. Angiographic imaging was done to isolate and locate the bleeding, and coil embolization of the gastroduodenal artery was performed. Coils eroded into intestinal lumen but bleeding was controlled. CONCLUSION: Peptic ulcers in pediatric populations are rare and complex in nature. Besides aggressive resuscitation and endoscopy, other methods to control bleeding such as coil embolization can be performed. Further investigations are needed to understand long-term effects of coil embolization in pediatric peptic ulcer patients. LEVEL OF EVIDENCE: 5/Case Report/.