Outcomes of Popliteal Stent-Graft Placement at the Artery Hinge Point for Popliteal Artery Aneurysm.

BACKGROUND: To assess whether stent-grafts crossing the hinge point (HP) in the popliteal artery are associated with increased complications and decreased patency rates, after endovascular treatment of the popliteal artery aneurysm. METHODS: This was a single-center, case-control study. Patients were allocated to either the HP group (subjects with stent-grafts crossing the HP) or the control group (subjects with stent-grafts above and/or below the HP) based on stent-graft location in the femoropopliteal artery. HP was defined as the main curve in the popliteal artery in the most acute angle toward the femur that appeared during knee flexion, which was identified by reviewing postoperative angiograms. Independent, blinded reviews were performed for all imaging data. Graft evaluation by CTA or duplex ultrasound was performed at 1, 3, 6, and 12 months and annually thereafter. Outcomes measured included: stent-graft patency, stent-graft fracture, other stent-related complications, and major adverse events, including reintervention, death, amputation, stroke, and myocardial infarction. RESULTS: A total of 44 limbs treated with placement of heparin-bonded Viabahn endoprostheses were included in this study. Twenty and twenty-four patients were allocated to the HP group and the control group, respectively. Primary patency rates of the HP group at 1, 2, 3, and 5 years were 84.1 ± 8.4%, 84.1 ± 8.4%, 84.1 ± 8.4%, and 72.1 ± 13.3%, respectively. The primary patency rates of the control group were 87.0 ± 7.0%, 82.4 ± 8.0%, 82.4 ± 8.0%, and 82.4 ± 8.0%, respectively. There was no significant difference between the 2 groups (P = 0.81). No reintervention was performed in the control group. In the HP group, 5 limbs (25.0%) developed endoleak, 3 (15.0%) developed thrombosis, and 1 (5.0%) developed a stent fracture followed by thrombosis. Thrombosis occurred in 2 limbs (8.3%) of the control group, and stent-graft migration was observed in another 2 cases (8.3%). Neither group demonstrated stent-graft infection or acute popliteal artery embolism. Overall, incidence of stent-related complications were significantly higher in the HP group (P= 0.04). Event-free survival rates of the HP group at 1, 2, 3, and 5 years were 75.0 ± 9.7%, 69.6 ± 10.4%, 61.9 ± 11.8%, and 29.0 ± 12.8%, respectively. Corresponding rates in the control group were 79.2 ± 8.3%, 79.2 ± 8.3%, 79.2 ± 8.3%, and 79.2 ± 8.3%, respectively. The difference was not statistically significant between the 2 groups (P = 0.20) CONCLUSIONS: crossing the HP with femoropopliteal artery stent-grafts increased the risk of stent-related complications and reinterventions but did not decrease stent patency or event-free survival.

The Effect of Patient Oral Intake Status on Abdominal Aortic Ultrasound Visualization.

BACKGROUND: The standard abdominal aortic duplex ultrasound protocol requires fasting for 8-12 hours prior to examination in attempt to reduce bowel gas and improve visualization. Such practice results in frequent testing delays and patient non-compliance. The aim of this study was to determine whether fasting improves visualization of the abdominal aorta in patients undergoing duplex ultrasound or influences diagnostic properties. METHODS: This was a prospective, randomized, double-blind imaging trail at a single institution. Ninety patients were randomized to one of three dietary groups, including NPO, clear liquids or control (regular diet). Diagnostic ultrasound examinations were performed by accredited Registered Vascular Technologists who remained blinded to the patients' diet. Sonographers commented on the presence of limited visualization in the study based on their ability to accurately measure aortic diameter. Examination results were randomly assigned to interpreting physicians who were also blinded to the patients' diet. Following interpretation, the reading physician was asked to comment whether they had sufficient information for a conclusive diagnostic interpretation. RESULTS: All ultrasound studies were deemed diagnostic by the interpreting physician regardless of the patients' dietary status. Limited visualization was reported in 19 of the 90 study patients (21.1%) with no significant difference existing between the dietary groups (P = 0.344). The NPO group contained the most patients with studies deemed to have limited visualization. CONCLUSION: Oral intake status did not affect visualization of the abdominal aorta or the rate of diagnostic studies in patients undergoing DUS at a single center. These results suggest that dietary restrictions prior to DUS evaluation of the abdominal aorta is unnecessary.

Shear rate is a better marker of symptomatic ischemic cerebrovascular events than velocity or diameter in severe carotid artery stenosis.

OBJECTIVE: This study was designed to test the hypothesis that the high shear rate of flow in the area of carotid stenosis is associated with the incidence of ischemic symptoms in patients with a high degree of carotid stenosis. METHODS: This is a case-control study of patients with >70% stenosis of the internal carotid artery (ICA) identified by duplex ultrasound in an Intersocietal Accreditation Commission-accredited laboratory during 1 year. Symptomatic patients were included in the study group, and asymptomatic patients served as controls. Shear rates were calculated from high-resolution ultrasound images. Descriptive statistics and univariate and multivariate analysis were performed to account for confounding factors. Receiver operating characteristic curves were used to compare diagnostic values of shear rate, velocities, and diameters of the ICA. RESULTS: The study included 308 patients (55.5% male; mean age, 73 ± 10 years); 209 of them were asymptomatic and 99 were symptomatic. The mean shear rate was 7930 s-1 for asymptomatic and 9338 s-1 for symptomatic patients. Receiver operating characteristic curve identified a cutoff value of 8000 s-1 to differentiate between symptomatic and asymptomatic patients; 92% of asymptomatic patients and 8.0% of symptomatic patients had a shear rate of <8000 s-1 compared with 48.5% asymptomatic and 51.5% symptomatic who had a shear rate ≥8000 s-1. Patients who had a shear rate higher than this cutoff value were 12 times more likely to be symptomatic than those with a shear rate <8000 s-1 (odds ratio, 12.1; 95% confidence interval, 6.12-24.09). Sensitivity and specificity were 84.8% and 61.2%, respectively. CONCLUSIONS: In patients with >70% ICA stenosis, the shear rate is associated with the prevalence of symptomatic cerebrovascular ischemic events. A shear rate of 8000 s-1 and above may be used as a predictor for having symptomatic cerebrovascular ischemic events. Further validation as well as further study of the pathologic mechanism connecting the high shear rate and ischemic cerebrovascular events is needed.

Timing of Hospital-acquired Venous Thromboembolism and Its Relationship with Venous Thromboembolism Prevention Measures in Immobile Patients.

BACKGROUND: The aim of this study is to describe the timing of venous thromboembolism (VTE) diagnosis in patients with cerebral or spinal trauma and stroke and describe the relationships between VTE prophylaxis and timing of VTE diagnosis at a community hospital. METHODS: Retrospective cohort observational study over a span of 10 years from 2006 to 2016 was conducted. RESULTS: Lower extremity ultrasound surveillance identified 138 patients who developed VTE during their hospital stay (mean age 62 years, 61.6% males). Mechanical prophylaxis was used in 79.7% and pharmacologic prophylaxis in 78.3% of patients. The average time of admission to administration of mechanical prophylaxis was 1.92 and 7.7 days for pharmacologic prophylaxis. In patients who received pharmacologic prophylaxis within 2 days, 51.5% of all VTE events occurred during the first week, 73.5% by the second week, and 91.2% by the third week of the hospital stay. In patients who started pharmacologic prophylaxis after 2 days in the hospital, 85% of all VTE events occurred within the first week and 90% within 10 days of the hospital stay (P < 0.001). The timing of initiation of mechanical prophylaxis did not influence the timing of VTE events. CONCLUSIONS: In immobilized patients with stroke, traumatic brain injury, or spinal cord injury, VTE screening should be performed at different schedules based on the timing of initiation of pharmacologic prophylaxis. In patients who did not start prophylaxis during the first 2 days of admission to the hospital, the majority of the VTE events occurred during the first 10 days.

Cost-Effectiveness Analysis of Initial Treatment Strategies for Nonembolic Acute Limb Ischemia Using Real-Word Data.

BACKGROUND: Nonembolic acute limb ischemia (ALI) is a condition characterized by a sudden decrease in limb perfusion and requires immediate interventions. There are multiple treatment options available including surgery, catheter-directed thrombolysis (CDT), endovascular procedures, and hybrid treatment (a combination of open and endovascular techniques). Randomized trials provide information only on clinical efficacy, but not on economic outcomes. The objective of the study was to perform the cost-effective analysis comparing different treatment alternatives of ALI. METHODS: The data were collected from 4r ProMedica community hospitals in the Northwest Ohio from January 2009 to December 2012. Patients were included if they were treated within 14 days of onset of symptoms for nonembolic ALI and were divided into groups of receiving CDT, surgery, endovascular, or hybrid treatments. Demographics, comorbidities, medications taken before admission, and smoking status were collected at baseline for all patients and were compared among the treatment groups. A cost-effectiveness decision tree was developed to calculate expected costs and life years gained associated with available treatment options. A probabilistic sensitivity analysis was also performed to check the robustness of the model. RESULTS: A population of 205 patients with the diagnosis of ALI was included and divided into different treatment groups. There was no major significant difference in baseline characteristics among the studied groups (P > 0.05). The total costs were $17,163.47 for surgery, $20,620.39 for endovascular, $21,277.61 for hybrid, and $30,675.42 for CDT. The life years gained were 17.25 for surgery, 18 for endovascular, 18 for hybrid, and 17 for CDT. CDT was dominated because of the high cost and the low effectiveness, while hybrid treatment was dominated when compared with endovascular treatment because these 2 treatments have similar outcomes. The incremental cost-effectiveness ratio of the endovascular group over the surgery group was found to be $4,609.23 per life year gained. The sensitivity analysis showed that the endovascular treatment was found to be cost-effective under willingness to pay $50,000. CONCLUSIONS: This study provides economic evaluation of ALI treatments for a defined clinical population in the real-world setting. Compared with other available alternatives, the endovascular treatment showed to be a cost-effective use of healthcare resources.

Clinical outcomes and cost-effectiveness of initial treatment strategies for nonembolic acute limb ischemia in real-life clinical settings.

OBJECTIVE: The optimal initial treatment for patients with acute limb ischemia (ALI) remains undefined. Although clinical outcome data are inconsistent, catheter-directed thrombolysis (CDT) with tissue plasminogen activator is increasingly used. Patient-level analysis combining clinical and economic data in a real-life setting is lacking. This study compared clinical outcomes and cost-effectiveness of initial treatment strategies for nonembolic ALI using real-life patient-level data. METHODS: Medical records and data for hospital costs were analyzed for nonembolic ALI patients treated in four hospitals over 3 years. A cost-effectiveness analysis was performed using a decision tree analytic model. All costs were valued based on cost-to-charge ratios. RESULTS: In 205 patients, initial treatments were CDT alone in 68 or with angioplasty in 16, open surgery in 60, endovascular in 33, and hybrid in 28. Although clinical outcomes did not differ significantly among the groups, reintervention rates during hospital stay, readmission rates, and costs were highest in the CDT group. Reintervention was required in 62% of patients after CDT compared with 7% after open surgery, and 16% of the CDT patients needed more than one reintervention. The mean total hospital cost was $34,800 per patient in CDT group compared with $10,677 in open surgery group. CONCLUSIONS: In this real-life study, initial treatment of nonembolic ALI with currently available CDT options was associated with greater health care resource consumption and cost compared with other initial treatment options.

Diagnosis of chronic iliac venous obstruction.

Stenting has become the first line of treatment for symptomatic chronic iliofemoral venous obstruction in patients with quality-of-life-impairing clinical manifestations who have failed conservative therapy. Patient selection for such intervention is, however, dependent on clear identification of relevant clinical manifestations and subsequent testing to confirm the diagnosis. In this regard, the physician engaged in management of such patients needs to be well-aware of symptoms and signs of chronic iliofemoral venous obstruction, and instruments used to grade chronic venous insufficiency and determine quality of life, in addition to diagnostic tests available and their individual roles. This review serves to provide an overview of the diagnosis of chronic iliofemoral venous obstruction and patient selection for stenting.

Venous valve hypoxia as a possible mechanism of deep vein thrombosis: a scoping review.

INTRODUCTION: The pathogenesis of deep vein thrombosis (DVT) has been explained by an interplay between a changed blood composition, vein wall alteration, and blood flow abnormalities. A comprehensive investigation of these components of DVT pathogenesis has substantially promoted our understanding of thrombogenesis in the venous system. Meanwhile, the process of DVT initiation remains obscure. This systematic review aims to collect, analyze, and synthesize the published evidence to propose hypoxia as a possible trigger of DVT. EVIDENCE ACQUISITION: An exhaustive literature search was conducted across multiple electronic databased including PubMed, EMBASE, Scopus, and Web of Science to identify studies pertinent to the research hypothesis. The search was aimed at exploring the connection between hypoxia, reoxygenation, and the initiation of deep vein thrombosis (DVT). The following key words were used: "deep vein thrombosis," "venous thrombosis," "venous thromboembolism," "hypoxia," "reoxygenation," "venous valve," and "venous endothelium." Reviews, case reports, editorials, and letters were excluded. EVIDENCE SYNTHESIS: Based on the systematic search outcome, 156 original papers relevant to the issue were selected for detailed review. These studies encompassed a range of experimental and observational clinical research, focusing on various aspects of DVT, including the anatomical, physiological, and cellular bases of the disease. A number of studies suggested limitations in the traditional understanding of Virchow's triad as an acceptable explanation for DVT initiation. Emerging evidence points to more complex interactions and additional factors that may be critical in the early stages of thrombogenesis. The role of venous valves has been recognized but remains underappreciated, with several studies indicating that these sites may act as primary loci for thrombus formation. A collection of studies describes the effects of hypoxia on venous endothelial cells at the cellular and molecular levels. Hypoxia influences several pathways that regulate endothelial cell permeability, inflammatory response, and procoagulation activity, underpinning the endothelial dysfunction noted in DVT. CONCLUSIONS: Hypoxia of the venous valve may serve as an independent hypothesis to outline the DVT triggering process. Further research projects in this field may discover new molecular pathways responsible for the disease and suggest new therapeutic targets.