Evaluation of safety and performance of a new prototype self-expandable nitinol venous stent in an ovine model.

Objective: Our study was a prospective in vivo study performed on an animal model to evaluate the safety and performance of a novel venous stent designed specifically for venous applications. Methods: The novel stents were implanted in the inferior vena cava of nine sheep. The stents were deployed with different distances between the closed cell rings to test for if the segments might migrate after being deployed at maximal distance. Three different total lengths were 9, 11, and 13 cm. After 1, 3, and 6 months, vascular injury, thrombus, neointima coverage, and stent migration were evaluated through computed tomography venography and histopathology. Imaging, histology, and integration data were analyzed for each group. Results: All stents were deployed successfully, and all sheep survived until the time of harvesting. In all cases, the native blood vessel sections were intact. The segmented stent parts showed a differently pronounced tissue coverage, depending on the duration of the implantation. Conclusions: The new nitinol stent is safe and feasible to implant in the venous system with a rapid surface coverage. Alteration of stent length did not affect the development of neointimal formation and did not cause migration.

Single-center experience with catheter-directed thrombolysis and balloon angioplasty for acute upper-extremity deep vein thrombosis: a case series study.

BACKGROUND: Effective treatment of upper extremity deep vein thrombosis (UEDVT) is crucial to prevent further complications. Various treatments, including percutaneous mechanical thrombectomy (PMT), catheter-directed thrombolysis (CDT), decompression surgery, and venoplasty are suggested for UEDVT. However, no prospective study has yet favored any of these treatments. This study presents a review of our experience with CDT followed by balloon venoplasty in patients with acute primary UEDVT. METHODS: We enrolled all patients diagnosed with acute UEDVT from January 2020 to June 2021. Subjects with UEDVT due to secondary causes like malignancies, indwelling catheters, or leads were excluded. CDT was performed through brachial vein access, using a perfusion catheter, and rt-PA administration. Balloon venoplasty was performed if the treated segment had remaining stenosis after CDT. Patients were followed up at the vein clinic for any signs and symptoms in the upper extremity and lifestyle changes. Follow-up ultrasonography was done 12 months after discharge. RESULTS: Twelve patients with a mean age of 41.08 ± 14.0 years were included in the study. The mean duration of CDT was 25.00 ± 10.56 h. After CDT, all patients had remaining occlusions, with seven having more than 50% remaining stenosis. However, after balloon venoplasty, no patient had significant (more than 50%) stenosis. There was no serious complication after both procedures. Patients were followed up for a mean duration of twelve months after their admission, with a mean time of maintenance anticoagulation was 10.73 ± 5.77 months. Only one patient had recurrent symptoms in his target limb which required a decompression surgery, while the rest were free of symptoms in their treated extremity. No subject developed pulmonary emboli (PE) during admission or the follow-up period. There was no evidence of hospital readmission for any reason. Upper extremity color-doppler sonography of the patients at twelve months after their procedure showed normal venous flow without any significant stenosis in 8 (66.7%), and partially normal flow with patent target vein in 4 (33.3%) patients. CONCLUSIONS: CDT followed by balloon venoplasty may be an effective treatment for selected patients with acute primary UEDVT, providing desirable long-term results and potentially avoiding the need for decompression surgery in the short or long term.

Development of a prediction model for deep vein thrombosis in a retrospective cohort of patients with suspected deep vein thrombosis in primary care.

OBJECTIVE: Early and accurate prediction and diagnosis of deep vein thrombosis (DVT) is essential to allow for immediate treatment and reduce potential complications. However, all potentially strong risk factors have not been included in pretest probability assessments such as the Wells score. In addition, the Wells score might not be suitable for use in primary care because it was developed for secondary care. We hypothesized that the addition of more risk factors for DVT to existing diagnostic approaches could improve the prediction of DVT. METHODS: All consecutive patients suspected of having DVT from 2004 to 2016 in a primary care setting were included in our retrospective study. All the patients had undergone Wells score, D-dimer, and duplex ultrasound assessments. The available recorded data of the patients were used to develop a model to predict DVT. RESULTS: Of 3381 eligible patients, 489 (14.5%) had confirmed DVT. The developed model, which included the D-dimer level, Wells score, gender, anticoagulation use, age, and family history of venous thrombosis, was able to distinguish patients with DVT among those with suspected DVT with a sensitivity of 82% (95% confidence interval, 78%-86%) and specificity of 82% (95% confidence interval, 80%-83%). CONCLUSIONS: The proposed model was able to predict for the presence of DVT among all patients with suspected DVT in a primary care setting with reasonable accuracy. Further validation in prospective studies is required.

Comparison of endovascular strategy versus hybrid procedure in treatment of chronic venous obstructions involving the confluence of common femoral vein.

OBJECTIVE: Treatment of extensive chronic venous obstruction (CVO) with post-thrombotic trabeculation involving the common femoral vein with extension into the femoral vein or deep femoral vein remains a challenge and the best treatment technique for such cases is not clear. In the present study, we compared the results of endovascular alone vs endovascular with additional endophlebectomy (hybrid) procedures for such patients. METHODS: The medical records of 102 consecutive patients (108 limbs) treated between 2015 and 2020 for iliofemoral CVO extending to the femoral confluence were retrospectively reviewed. The patients were divided into two groups: the hybrid procedure (HP) and endovascular treatment (EN) groups. The HP group consisted of those treated with stent implantation and endophlebectomy of the common femoral vein with creation of an arteriovenous fistula. The EN group included those who had undergone stent implantation alone. The patency rates, complications, and clinical outcomes were analyzed. RESULTS: Of the 102 patients, 47 (49 limbs) were in the EN group and 55 (59 limbs) were in the HP group. The demographics of the two groups were similar with no statistically significant differences in cumulative primary, assisted primary, or secondary patency rates at 36 months (33.7% vs 36.3%, P = .839; 59.8% vs 64%, P = .941; 69% vs 72.7%, P = .851; respectively). The patients in the EN group, however, had better clinical improvement with a lower postoperative complication rate (P = .012), shorter procedure duration (P < .001), and shorter hospital stay (P = .025). CONCLUSIONS: The EN and HP both provided similar patency rates for patients with CVO extending into the femoral confluence. The endovascular strategy has the benefit of fewer postoperative complications and a shorter procedure duration and hospital stay compared with the HP.

A risk score for iliofemoral patients with deep vein thrombosis.

OBJECTIVE: Deep vein thrombosis (DVT) is a common condition with a high risk of post-thrombotic morbidity, especially in patients with a proximal thrombus. Successful iliofemoral clot removal has been shown to decrease the severity of post-thrombotic syndrome. It is assumed that earlier thrombus lysis is associated with a better outcome. Generally, the earlier IFDVT is confirmed, the earlier thrombus lysis could be performed. d-Dimer levels and Wells score are currently used to assess the preduplex probability for DVT; however, some studies indicate that the d-dimer value varies depending on the thrombus extent and localization. Using d-dimer and other risk factors might facilitate development of a model selecting those with an increased risk of IFDVT that might benefit from early referral for additional analysis and adjunctive iliofemoral thrombectomy. METHODS: All consecutive adult patients from a retrospective cohort of STAR diagnostic center (primary care) in Rotterdam suspected of having DVT between September 2004 and August 2016 were assessed for this retrospective study. The diagnostic workup for DVT including Wells score and d-dimer were performed as well as complete duplex ultrasound examination. Patients with objective evidence of DVT were categorized according to thrombus localization using the Lower Extremity Thrombolysis classification. Logistic regression analysis was done for a model predicting IFDVT. The cut-off value of the model was determined using a receiver operating characteristic curve. RESULTS: A total of 3381 patients were eligible for study recruitment, of whom 489 (14.5%) had confirmed DVT. We developed a multivariate model (sensitivity of 77% and specificity of 82%; area under the curve, 0.90; 0.86-0.93) based on d-dimer, Wells score, age, and anticoagulation use, which is able to distinguish IFDVT patients from all patients suspected of DVT. CONCLUSIONS: This multivariate model adequately distinguishes IFDVT among all suspected DVT patients. Practically, this model could give each patient a preduplex risk score, which could be used to prioritize suspected IFDVT patients for an immediate imaging test to confirm or exclude IFDVT. Further validation studies are needed to confirm potential of this prediction model for IFDVT.

Prevalence and outcome of abdominal vascular injury in severe trauma patients based on a TraumaRegister DGU international registry analysis.

This study details the etiology, frequency and effect of abdominal vascular injuries in patients after polytrauma based on a large registry of trauma patients. The impact of arterial, venous and mixed vascular injuries on patients' outcome was of interest, as in particular the relevance of venous vessel injury may be underestimated and not adequately assessed in literature so far. All patients of TraumaRegister DGU with the following criteria were included: online documentation of european trauma centers, age 16-85 years, presence of abdominal vascular injury and Abbreviated Injury Scale (AIS) ≥ 3. Patients were divided in three groups of: arterial injury only, venous injury only, mixed arterial and venous injuries. Reporting in this study adheres to the STROBE criteria. A total of 2949 patients were included. All types of abdominal vessel injuries were more prevalent in patients with abdominal trauma followed by thoracic trauma. Rate of patients with shock upon admission were the same in patients with arterial injury alone (n = 606, 33%) and venous injury alone (n = 95, 32%). Venous trauma showed higher odds ratio for in-hospital mortality (OR: 1.48; 95% CI 1.10-1.98, p = 0.010). Abdominal arterial and venous injury in patients suffering from severe trauma were associated with a comparable rate of hemodynamic instability at the time of admission. 24 h as well as in-hospital mortality rate were similar in in patients with venous injury and arterial injury. Stable patients suspected of abdominal vascular injuries should be further investigated to exclude or localize the possible subtle venous injury.

Outcome of stenting in central venous obstruction of benign etiology.

Background: The aim of this study is to evaluate long term outcome in patients treated for benign superior vena cava (SVC) syndrome by endovascular techniques. Patients and methods: Between 2015 and 2018, 62 patients suffering from central venous obstruction of benign etiology underwent balloon angioplasty with stent placement for venous obstruction in our department. Patency was assessed clinically, using duplex ultrasound in all patients or with CT-phlebography in selected cases. Results: Median age was 60 years (23-83), forty-one patients (66%) had central venous devices. Swelling of the arm and face were the main symptoms (71%). During the median follow up of 22 months (9-38), cumulative primary patency was 71% after venous stenting. The cumulative assisted primary and the secondary patency were 85% and 92%, respectively. Conclusions: Recanalization and stenting of central vein obstruction has turned out to be the technique of reference and provides satisfactory mid-term patency rates. After adjusting for the risk factors, presence of AV-fistula remained a significant risk factor for recurrent stenosis or loss of patency after intervention.

Iliocaval Skip Stent Reconstruction Technique for Chronic Bilateral Iliocaval Venous Occlusion.

PURPOSE: To report safety and efficacy of a skip stent technique using nitinol stents in patients with chronic bilateral iliocaval venous occlusions. MATERIALS AND METHODS: A retrospective analysis of 48 consecutive patients (32 men; mean age, 40.7 years; age range, 18-68 years) with chronic bilateral iliocaval obstructions treated using a nonoverlapping stent technique was conducted at a single center. None of the patients had May-Thurner syndrome. Iliocaval confluence was treated by deploying a nitinol stent in inferior vena cava (IVC) and a nitinol stent in each common iliac vein close to the caval stent. Patency of stents was assessed by duplex US at 2 weeks, 3 months, and 6 months and yearly thereafter. RESULTS: Recanalization and stent reconstruction was technically successful in 47 (98%) patients. The sinus-XL venous stent was used to treat IVC (95 [100%]). Common iliac and external iliac veins were treated with sinus-Venous and VENOVO stents (80 [83%] and 16 [17%] limbs, respectively). External iliac and common femoral veins were treated with sinus-Venous and VENOVO stents (83 [92%] and 7 [18%] limbs, respectively). Early thrombosis (< 30 days) of the iliac vein with stent occurred in 2 limbs. Cumulative primary, assisted primary, and secondary patency rates at 30 months were 74%, 83%, and 97%. CONCLUSIONS: Findings of this study suggest that leaving a skipped lesion at the level of iliocaval confluence may not adversely affect stent patency. Patency rates were comparable with other reported techniques of stent reconstruction at the level of iliocaval confluence.

Update on diagnosis and treatment strategies in patients with post-thrombotic syndrome due to chronic venous obstruction and role of endovenous recanalization.

OBJECTIVE: After a first episode of lower extremity deep venous thrombosis, post-thrombotic syndrome (PTS) develops in 20% to 50% of patients despite adequate anticoagulation. Symptoms of PTS can vary from leg swelling to venous ulceration with disabling venous claudication. It significantly affects the patient's quality of life and has considerable socioeconomic consequences. This review gives an update on diagnosis and current treatment strategies in patients with PTS due to chronic venous obstruction, in particular regarding the role of endovenous procedures. METHODS: This review article is based on a selective literature search in PubMed and the Cochrane Library. The terms "postthrombotic syndrome," "post-thrombotic syndrome," "chronic venous obstruction," "venous outflow obstruction," and "venous stent" were used as keywords. Selected publications addressed the diagnosis of and therapy for PTS. Acute deep venous thrombosis, thrombolysis, case reports, complications as a result of caval vein filters, animal experiments, PTS of the upper extremity, and PTS in children were excluded. RESULTS: In addition to conservative treatment of PTS, the following invasive procedures are also available: open surgical reconstructions, hybrid procedures, and endovenous recanalization of the occluded iliocaval venous tract with stent angioplasty. Since introduction of dedicated venous stents in 2012, technical success, patency rates, and improvement in quality of life have been at least as good as results of open surgical reconstruction if not better. CONCLUSIONS: First-line treatment should be conservative therapy. In case of therapy-resistant PTS with poor quality of life, the possibility of an invasive treatment should be evaluated. All invasive procedures are recommended with low levels of evidence. Therefore, deciding on an invasive treatment and type of procedure should be made individually. Because PTS is rarely a threat to life or limb, a minimally invasive treatment is preferred. Therefore, endovenous recanalization appears to be appropriate as the therapy of choice. In patients with involvement of the femoral confluence, endophlebectomy of the common femoral vein in addition to venous recanalization is inevitable to ensure an adequate inflow into the recanalized venous tract. It also secures a sufficient drainage of blood from the peripheral venous system. Because this hybrid procedure is burdened with a significantly higher risk of complications, strict criteria must be fulfilled to legitimize the indication for this procedure. For the best possible results to be achieved, the following perioperative and postoperative management must be considered: therapeutic anticoagulation, early mobilization, compression therapy, and systematic follow-up with duplex ultrasound.

Assessing radiation exposure to patients during endovascular treatment of chronic venous obstruction.

BACKGROUND: Post-thrombotic obstruction can be adequately treated by percutaneous transluminal angioplasty and stenting. This procedure is rapidly emerging as a minimally invasive alternative to traditional open surgical operations. However, the patient will be exposed to a significant amount of radiation during preoperative planning and operation. The aim of this study was to evaluate the amount of radiation exposure to patients during venous recanalization. METHODS: All patients undergoing endovenous recanalization from February 2016 to February 2018 were included in this study. The operations were performed in an operating room using a mobile C-arm angiography system. Indirect parameters of cumulative air kerma, kerma-area product, and fluoroscopy time (FT) were recorded concurrently with direct measurements of dose (effective dose [ED]) in the pelvic and neck area using two electronic personal dosimetry devices. The direct measured doses were then correlated with indirect parameters provided by the imaging equipment manufacturers. RESULTS: In total, 78 cases were included in the study. During a median operation time of 154.5 minutes (90-323 minutes), the median FT was 43.7 minutes (15.9-77.7 minutes). Body mass index did not correlate with FT or ED. ED correlated with duration of the intervention (r = 0.59) but better with FT, cumulative air kerma, and kerma-area product (r = 0.76, 0.94, and 1.00, respectively). No patients had evidence of radiation-induced skin injury. CONCLUSIONS: Radiation exposure to patients during endovenous recanalization does not reach the threshold to have a deterministic effect. Indirect parameters of radiation exposure correlated with direct measurements of the ED. Direct dosimetry is likely to be an unnecessary effort for these types of procedures when indirect dose metrics are available.

The Role of May-Thurner Syndrome in Recurrent Thrombosis after Catheter-Directed Thrombolysis of Deep Vein Thrombosis.

BACKGROUND: May-Thurner syndrome (MTS) leads to an increased incidence of deep vein thrombosis (DVT). Early thrombus removal decreases the post-thrombotic morbidities. Our aim was to better elucidate the relationship between MTS and venous patency after catheter-directed thrombolysis (CDT). METHODS: The medical records of all patients who underwent CDT from January 2005 to December 2011 due to acute DVT were reviewed retrospectively. Patient characteristics and clinical variables were evaluated to determine association with vein patency. RESULTS: A total of 51 male and 31 female with a mean age of 34.9 years were treated with CDT. During a median follow-up of 91.7 months, primary patency and secondary patency of all patients were 79.3% and 87.3%, respectively. The presence of MTS was the only significant predictor factor of patency. CONCLUSIONS: The residual stenosis caused by MTS is a risk for recurrent DVT and should be treated with stenting to improve the outcome.

Sheep models for evaluation of novel patch and prosthesis material in vascular surgery: tips and tricks to avoid possible pitfalls.

BACKGROUND: In vascular surgery, novel synthetic prosthesis materials for patch-angioplasties, interpositions, bypasses and shunts are continuously under development and optimization. The characteristics of an ideal vascular prosthesis would display long-term patency, biocompatibility, durability, low porosity, lack of stich hole bleeding, ease of handling, kink resistance, infection resistance and reasonable costs. The aim of this study was to establish and report a reliable sheep model including potential pitfalls where those parameters could be analyzed. Before surgery, sheep were acclimatized for 4-8 weeks, during which parasite infections were treated and blood and serum parameters monitored. Twenty-four sheep underwent surgery, and carotid patch-angioplasties (n = 12), graft interpositions (n = 6) or arteriovenous prosthetic shunts (n = 6) were implanted. Half of the animals in each group were sacrificed after 2 weeks and the other half after 8 weeks. The implants were analyzed for patency, endothelialization, thrombogenicity and biocompatibility by clinical observation, blood flow measurement and pathological and histopathological (H&E, EvG) as well as immunohistochemical (Ki67, CD31) evaluations. RESULTS: Health monitoring of the sheep revealed a parasitic burden with endoparasites in all animals. Some animals showed thereby infestations in the bile duct causing fibrotic cholangitis with calcifications in the liver. In addition, sarcosporidia were detected in histopathological specimen of the heart in all animals. Parasitic burden correlated with blood counts and serum bilirubin levels. Both were significantly reduced by albendazole treatment within the acclimatization time. Patches, interposition grafts, and straight shunts were successfully implanted bilaterally in all animals. The total average operation time was 136 ± 21 min. Most animals (23/24) showed good patency rates and general condition after implantation. Pathological and histopathological/immunohistochemical analyses were suitable to determine thrombogenicity, endothelialization, cellular/fibroblastic proliferation, biocompatibility, inflammatory cell infiltration, and thickness of neointima in the prosthesis material. CONCLUSIONS: We have developed a suitable experimental protocol with standardized and successful anesthesia- and surgical-procedures for patch-angioplasty, graft interposition, and arteriovenous prosthetic shunts. This sheep model allows testing of new prosthetic materials for biocompatibility, thrombogenicity, and endothelialization.

Blunt Thoracic Aortic Injury in Case of a 15-Year-Old Boy: Difficulties and Possibilities of the Endovascular Approach.

BACKGROUND: Blunt thoracic aortic injuries (BTAIs) are rare but life threatening. Most BTAI are caused by high-energy trauma. Among children with blunt trauma, the incidence of BTAI is below 1 percent. The present case deals with covered thoracic aortic rupture of a 15-year-old boy. Emphasizing the value and the difficulties of endovascular surgery in children is the motivation for this case report. CASE REPORT: We are presenting the case of a 15-year-old boy, who suffered multiple traumata after accident. Beneath multiple fractures and a liver laceration, a thoracic aortic rupture with pseudoaneurysm of the aortic wall was diagnosed. Owing to the comorbidities, an endovascular therapy in combination with a transposition of the left subclavian artery to the common carotid artery was performed. The chronological line-up of the events and the endovascular treatment as well as the in-hospital follow-up are described. DISCUSSION: Injury-induced BTAI in pubescent children rarely occurs. Only few cases can be found in literature, none of which were associated with the presented pattern of injury. CONCLUSIONS: The optimal treatment for childhood BTAI is a case-by-case decision. We critically discuss the value of endovascular therapy in the present case.

The Treatment of Post-Thrombotic Syndrome.

BACKGROUND: Post-thrombotic syndrome (PTS) arises in 20-50% of patients who have sustained a deep vein thrombosis and markedly impairs their quality of life. METHODS: This review is based on pertinent publications retrieved by a selective literature search in PubMed and the Cochrane Library, and on the guidelines of the German Societies of Phlebology and Vascular Surgery (Deutsche Gesellschaft für Phlebologie, Deutsche Gesellschaft für Gefässchirurgie). RESULTS: The treatment options are conservative treatment with compression and patient exercises, endovascular recanalization with stent angioplasty, and open bypass surgery of the iliac obstructions. The endovascular techniques yield patency rates of 73 to 100%, with thrombotic stent occlusion and hematoma as potential complications. The open operations have only been documented in studies with small case numbers (3 to 85 cases per study, patency rates 58 to 100%). The complications of these invasive procedures can include thrombotic bypass occlusion, hematoma, and wound infection. There have been randomized trials of conservative treatment, but not of surgical treatment. The American Heart Association, in its guidelines, gives the same weak recommendation for all surgical methods (IIb). CONCLUSION: All conservative options should be exhausted as the first line of treatment. If PTS symptoms persist and markedly impair the patient's quality of life, the possible indication for surgery should be considered. As PTS hardly ever leads to death or limb loss, its treatment should be as uninvasive as possible. Endovascular recanalization is an attractive option in this respect. A conclusive evaluation of the role of endovascular procedures in PTS must await randomized trials of this form of treatment and of the optimal stent configuration.