Standardized Methodology for Duplex Ultrasound Examination of Arteriovenous Access for Hemodialysis: A Proposal of the French Society of Vascular Medicine and the French-Speaking Society of Vascular Access.

Duplex ultrasound (DUS) is an essential tool for characterizing and monitoring arteriovenous (AV) access for hemodialysis. The aim of the work described here, requested by the French Society of Vascular Medicine in collaboration with the French-Speaking Vascular Access Society, is to propose a standardized methodology for performing and documenting DUS, taking into account the variety of AV access techniques and the problems routinely encountered. A steering committee reviewed the literature and selected the relevant references. A draft was prepared, and all items with missing or conflicting data were submitted to a Delphi consensus. The final document was discussed and approved by all participants. The principles of DUS evaluation of AV access consist of examination of the afferent artery, the anastomosis and the entire venous drainage system. DUS uses B-mode ultrasound, color flow, pulsed wave and power Doppler analysis. DUS can be used in a variety of clinical situations, which can directly influence the methodology of the examination and the interpretation of the results. Blood flow should be assessed as it correlates with the risk of thrombosis. The measurement should be adapted to the different anatomical and hemodynamic conditions encountered. Characterization of stenosis should take into account the residual diameter of the drainage vein and its hemodynamic consequences. Other complications can be assessed with a standardized DUS examination. When performed according to a rigorous methodology, DUS of the AV access allows a comprehensive assessment of its functionality and eliminates the need for further invasive diagnostic procedures.

Long-term risk of postthrombotic syndrome after symptomatic distal deep vein thrombosis: The CACTUS-PTS study.

BACKGROUND: After a proximal lower limb deep vein thrombosis (DVT; involving popliteal veins or above), up to 40% of patients develop postthrombotic syndrome (PTS) as assessed by the Villalta scale (VS). Poor initial anticoagulant treatment is a known risk factor for PTS. The risk of developing PTS after isolated distal DVT (infra-popliteal DVT without pulmonary embolism), and the impact of anticoagulant treatment on this risk, are uncertain. METHODS: Long-term follow-up of CACTUS double-blind trial comparing 6 weeks of s.c. nadroparin (171 IU/kg/d) versus s.c. placebo for a first symptomatic isolated distal DVT. At least 1 year after randomization, patients had a PTS assessment in clinic or by phone using the VS. RESULTS: After a median follow-up of 6 years, PTS was present in 30% (n = 54) of the 178 patients who had a PTS assessment. PTS was moderate or severe in 24% (n = 13) of cases. There was no statistically significant difference in prevalence of PTS in the nadroparin versus placebo groups (29% versus 32%, P = .6), except in patients without evidence of primary chronic venous insufficiency (9% versus 24%, P = .04). Rates of venous thromboembolism recurrence during follow-up in the nadroparin and placebo groups were, respectively, 8% (n = 7) and 14% (n = 13; P = .2). CONCLUSION: After a first isolated distal DVT, the risk of PTS is substantial but much lower than that reported after proximal DVT. Anticoagulation with nadroparin doesn't provide any clear benefit to prevent PTS, except in patients without preexisting chronic venous insufficiency. Anticoagulation might be associated with a lower risk of venous thromboembolism recurrence.

Anticoagulant therapy for symptomatic calf deep vein thrombosis (CACTUS): a randomised, double-blind, placebo-controlled trial.

BACKGROUND: The efficacy and safety of anticoagulant treatment is not established for patients with acute symptomatic deep vein thrombosis (DVT) of the calf. We aimed to assess whether therapeutic anticoagulation is superior to placebo in patients with symptomatic calf DVT. METHODS: In this randomised, double-blind, placebo-controlled trial, we enrolled low-risk outpatients (without active cancer or previous venous thromboembolic disease) with a first acute symptomatic DVT in the calf from 23 university medical centres or community medical clinics in Canada, France, and Switzerland. We randomly assigned (1:1) patients to receive either the low-molecular-weight heparin nadroparin (171 UI/kg, subcutaneously, once a day) or placebo (saline 0·9%, subcutaneously, once a day) for 6 weeks (42 days). Central randomisation was done using a computer-generated randomisation list, stratified by study centre. Random allocation sequences of variable block size were centrally determined by an independent research clinical centre. Study staff, patients, and outcome assessors (central adjudication committee) were masked to group assignment. Numbered boxes of active drug or placebo were provided to pharmacies in identical packaging. All patients were prescribed compression stockings and followed up for 90 days. The primary efficacy outcome was a composite measure of extension of calf DVT to proximal veins, contralateral proximal DVT, and symptomatic pulmonary embolism at day 42 in the modified intention-to-treat population. The primary safety outcome was major or clinically relevant non-major bleeding at day 42. The trial was registered with ClinicalTrials.gov, number NCT00421538. FINDINGS: Between Feb 1, 2008, and Nov 30, 2014, we screened 746 patients, enrolling 259 patients (50% of the prespecified sample size), before the trial steering committee terminated the trial because of expiry of study drug and slow recruitment. The intention-to-treat analysis population comprised 122 patients in the nadroparin group and 130 in the placebo group. There was no significant difference between the groups in the composite primary outcome, which occurred in four patients (3%) in the nadroparin group and in seven (5%) in the placebo group (risk difference -2·1%, 95% CI -7·8 to 3·5; p=0·54). Bleeding occurred in five patients (4%) in the nadroparin group and no patients in the placebo group (risk difference 4·1, 95% CI 0·4 to 9·2; p=0·0255). In the nadroparin group one patient died from metastatic pancreatic cancer and one patient was diagnosed with heparin-induced thrombocytopenia type 2. INTERPRETATION: Nadroparin was not superior to placebo in reducing the risk of proximal extension or venous thromboembolic events in low-risk outpatients with symptomatic calf DVT, but did increase the risk of bleeding. Avoidance of systematic anticoagulation for calf DVT could have a substantial impact on individual patients and from a public health perspective. FUNDING: Swiss National Science Foundation, the Programme Hospitalier de Recherche Clinique in France, and the Canadian Institutes of Health Research.