Mutations in EPHB4 cause human venous valve aplasia.

Venous valve (VV) failure causes chronic venous insufficiency, but the molecular regulation of valve development is poorly understood. A primary lymphatic anomaly, caused by mutations in the receptor tyrosine kinase EPHB4, was recently described, with these patients also presenting with venous insufficiency. Whether the venous anomalies are the result of an effect on VVs is not known. VV formation requires complex "organization" of valve-forming endothelial cells, including their reorientation perpendicular to the direction of blood flow. Using quantitative ultrasound, we identified substantial VV aplasia and deep venous reflux in patients with mutations in EPHB4. We used a GFP reporter in mice to study expression of its ligand, ephrinB2, and analyzed developmental phenotypes after conditional deletion of floxed Ephb4 and Efnb2 alleles. EphB4 and ephrinB2 expression patterns were dynamically regulated around organizing valve-forming cells. Efnb2 deletion disrupted the normal endothelial expression patterns of the gap junction proteins connexin37 and connexin43 (both required for normal valve development) around reorientating valve-forming cells and produced deficient valve-forming cell elongation, reorientation, polarity, and proliferation. Ephb4 was also required for valve-forming cell organization and subsequent growth of the valve leaflets. These results uncover a potentially novel cause of primary human VV aplasia.

Editor's Choice - A Comparison of Computed Tomography Angiography and Colour Duplex Ultrasound Surveillance Post Infrarenal Endovascular Aortic Aneurysm Repair: Financial Implications and Impact of Different International Surveillance Guidelines.

OBJECTIVE: Use of colour duplex ultrasound (CDUS) and computed tomography angiography (CTA) for infrarenal endovascular aortic aneurysm repair (EVAR) surveillance differs in internationally published guidelines. This study aimed firstly to compare CDUS detection of significant sac abnormalities with CTA. Secondly, a sensitivity analysis was conducted to compare financial estimates of the, predominantly CDUS based, local and Society of Vascular Surgery (SVS) protocols, the risk stratified European Society of Vascular Surgery (ESVS) protocol, and the CTA based National Institute of Health and Care Excellence (NICE) protocol. METHODS: Agreement between CDUS and CTA was assessed for detection of significant sac abnormalities. Surveillance protocols were extrapolated from published guidelines and applied to infrarenal EVAR patients active on local surveillance at a large, single centre. Surveillance intensity was dependent on presence of endoleak and subsequent risk of treatment failure in accordance with surveillance recommendations. Estimates for each surveillance protocol were inclusive of a range of published incidences of endoleak, contrast associated acute kidney injury (AKI), and excess hospital bed days, and estimated for a hypothetical five year surveillance period. RESULTS: The kappa coefficient between CDUS and CTA for detecting sac abnormalities was 0.68. Maximum five year surveillance cost estimates for the 289 active EVAR patients were £272 359 for SVS, £230 708 for ESVS, £643 802 for NICE, and £266 777 for local protocols, or £1 270, £1 076, £3 003, and £1 244 per patient. Differences in endoleak incidence accounted for a 1.1 to 1.4 fold increase in costs. AKI incidence accounted for a 3.3 to 6.2 fold increase in costs. CONCLUSION: A combined CTA and CDUS EVAR surveillance protocol, with CTA reserved for early seal assessment and confirmatory purposes, provides an economical approach without compromising detection of sac abnormalities. AKI, as opposed to direct imaging costs, accounted for the largest differences in surveillance cost estimates.

The efficacy of salvage interventions on threatened distal bypass grafts.

OBJECTIVE: Infrapopliteal bypass is an established and effective method for limb salvage in patients with critical limb ischemia. Secondary interventions maybe required to maintain graft patency. The aim of this study was to look at the frequency and outcomes of such interventions. METHODS: Consecutive patients undergoing bypasses onto the infrapopliteal vessels for critical limb ischemia (Rutherford 4-6) at a single institution were analyzed between 2009 and 2013. The primary end points were graft patency, amputation-free survival (AFS), and freedom from reintervention at 12 months by Kaplan-Meier analysis. RESULTS: A total of 114 infrapopliteal bypasses were performed in 102 patients. Distal anastomosis was on to the anterior tibial (n = 31), posterior tibial (n = 27), peroneal (n = 24), tibioperoneal trunk (n = 23), or dorsalis pedis artery (n = 9). Primary patency, assisted primary patency, and secondary patency was 57%, 76%, and 82%, respectively, at 12 months and 44%, 70%, and 80%, respectively, at 36 months. AFS was 80% at 12 months and 65% at 36 months. Endovascular salvage interventions were performed on 58 grafts (51%) including angioplasty of inflow/proximal anastomosis (33%), outflow/distal anastomosis (46%), and graft stenosis (20%), with a further 12 grafts (11%) undergoing thrombolysis for occlusion. Surgical salvage interventions included jump grafts (n = 7), revision of anastomotic stenosis (n = 3), and thrombectomy (n = 2). AFS was similar in salvaged threatened and acutely occluded grafts compared with nonthreatened grafts (P = .064) and better in grafts requiring reintervention later (>6 months from bypass) compared with those requiring early reintervention (<6 months; P = .047). CONCLUSIONS: Secondary interventions in threatened distal bypass grafts are successful at maintaining graft patency and AFS when compared with nonthreatened grafts, and are associated with a low morbidity rate.

Nonleg venous thrombosis in critically ill adults: a nested prospective cohort study.

IMPORTANCE: Critically ill patients are at risk of venous thrombosis, and therefore guidelines recommend daily thromboprophylaxis. Deep vein thrombosis (DVT) commonly occurs in the lower extremities but can occur in other sites including the head and neck, trunk, and upper extremities. The risk of nonleg deep venous thromboses (NLDVTs), predisposing factors, and the association between NLDVTs and pulmonary embolism (PE) or death are unclear. OBJECTIVE: To describe the frequency, anatomical location, risk factors, management, and consequences of NLDVTs in a large cohort of medical-surgical critically ill adults. DESIGN, SETTING, AND PARTICIPANTS: A nested prospective cohort study in the setting of secondary and tertiary care intensive care units (ICUs). The study population comprised 3746 patients, who were expected to remain in the ICU for at least 3 days and were enrolled in a randomized clinical trial of dalteparin vs standard heparin for thromboprophylaxis. MAIN OUTCOMES AND MEASURES: The proportion of patients who had NLDVTs, the mean number per patient, and the anatomical location. We characterized NLDVTs as prevalent or incident (identified within 72 hours of ICU admission or thereafter) and whether they were catheter related or not. We used multivariable regression models to evaluate risk factors for NLDVT and to examine subsequent anticoagulant therapy, associated PE, and death. RESULTS Of 3746 trial patients, 84 (2.2%) developed 1 or more non-leg vein thromboses (superficial or deep, proximal or distal). Thromboses were more commonly incident (n = 75 [2.0%]) than prevalent (n = 9 [0.2%]) (P < .001) and more often deep (n = 67 [1.8%]) than superficial (n = 31 [0.8%]) (P < .001). Cancer was the only independent predictor of incident NLDVT (hazard ratio [HR], 2.22; 95% CI, 1.06-4.65). After adjusting for Acute Physiology and Chronic Health Evaluation (APACHE) II scores, personal or family history of venous thromboembolism, body mass index, vasopressor use, type of thromboprophylaxis, and presence of leg DVT, NLDVTs were associated with an increased risk of PE (HR, 11.83; 95% CI, 4.80-29.18). Nonleg DVTs were not associated with ICU mortality (HR, 1.09; 95% CI, 0.62-1.92) in a model adjusting for age, APACHE II, vasopressor use, mechanical ventilation, renal replacement therapy, and platelet count below 50 × 10(9)/L. CONCLUSIONS AND RELEVANCE Despite universal heparin thromboprophylaxis, nonleg thromboses are found in 2.2% of medical-surgical critically ill patients, primarily in deep veins and proximal veins. Patients who have a malignant condition may have a significantly higher risk of developing NLDVT, and patients with NLDVT, compared with those without, appeared to be at higher risk of PE but not higher risk of death. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00182143.

Effectiveness of alternative strategies to define index case phenotypes to aid genetic diagnosis of familial hypercholesterolaemia.

OBJECTIVE: To determine the utility of secondary stratification measures to improve the ascertainment of index cases of familial hypercholesterolaemia (FH). DESIGN: A retrospective study of genotyped index patients with Simon Broome (SB) FH. SETTING: University teaching hospital. PATIENTS: 204 patients aged 55±14 years; 36% had tendon xanthoma (TX), 21% had coronary heart disease (CHD), low-density lipoprotein cholesterol (LDL-C) was 6.20±2.24 mmol/l and 55% had genetic FH. INTERVENTIONS: The effects of different staging systems (SB vs Dutch criteria), presence of TX, use of LDL-C level, personal history of CHD and imaging evidence of atheroma by carotid intima-media thickness or coronary artery calcium score to identify genetic FH was explored. OUTCOME MEASURES: Changes in C-statistic and net reclassification index (NRI). RESULTS: SB criteria gave a C-statistic of 0.64 comprising C=0.65 in TX(+) and C=0.5 in TX(-) patients. Genetic FH was present in 75% of TX(+) compared with 44% in TX(-) patients. The Dutch criteria gave C=0.72. Addition of imaging criteria to prior CHD raised C=0.64 to C=0.65 in all patients with a NRI of 19% (p=0.06). In TX(-) patients imaging raised C=0.50 to C=0.65 with a NRI of 0.38 (p=0.001) and a weighted comparison index of 0.28, implying the detection of 14 more FH cases per thousand. CONCLUSIONS: Patients with tendon xanthoma (definite FH) should be genotyped. In patients with possible FH, the presence of a personal history of CHD or imaging evidence of increased atheroma offers the best method of identifying index patients likely to have monogenic FH.

Problems with implementing a standardised transcranial Doppler screening programme: impact of instrumentation variation on STOP classification.

BACKGROUND: The Stroke Prevention Trial in Sickle Cell Anaemia (STOP) demonstrated the value of selective transfusion based on transcranial Doppler (TCD) US screening. This facilitated widespread surveillance, but due to reported differences with non-imaging TCD, imaging velocity thresholds have been reduced in some centres. OBJECTIVE: (1) Retrospectively review velocity measurements obtained by non-imaging and imaging TCD, using a standardised protocol. (2) Determine the impact on STOP classification of different velocity thresholds. MATERIALS AND METHODS: TCD data from 23 children (2-19 years of age) were reviewed. The TCD protocol focused on obtaining the velocity corresponding to the highest audible Doppler frequency. STOP velocity thresholds were the recommended for non-imaging TCD and values reduced by 5-15%. RESULTS: Non-imaging and imaging TCD velocities were correlated closely with little overall bias. Reducing imaging TCD velocity thresholds increased the number of abnormal and conditional classifications. Abnormal TCD imaging classifications ranged from 1.9% to 37% depending on the degree of correction applied to the velocity data. CONCLUSION: The current approach for applying STOP thresholds to imaging TCD data may not be required. Centres need to validate their imaging TCD practice to avoid inappropriate selection of patients for transfusion therapy.

Generalized arterial calcification of infancy: phenotypic spectrum among three siblings including one case without obvious arterial calcifications.

Generalized arterial calcification of infancy (GACI) (OMIM no. 208000) is characterized by calcification of the major arteries and soft tissues and associated with mutations in the ENPP1 gene. Most affected patients die within the first 6 months of life although prolonged survival is increasingly recognized. We report on three siblings with GACI and striking phenotypic variability. Two siblings (including the sibling survivor) were compound heterozygotes for mutations in exon 7 (c.783C>G (p.Y261X)) and exon 8 (c. 878_879delAA (p.K293fsX5)) of the ENPP1 gene confirming the diagnosis of GACI. The sibling survivor did not have calcification on X-ray studies or evidence of hypophosphatemic rickets. GACI may be under recognized and we emphasize consideration of this condition in patients with multiple arterial stenosis even in the absence of radiographic calcification. This adds to the expanding phenotype of GACI and supports a potential role for modifying genes.

Novel candidate genes in unstable areas of human atherosclerotic plaques.

OBJECTIVE: Comparison of gene expression in stable versus unstable atherosclerotic plaque may be confounded by interpatient variability. The aim of this study was to identify differences in gene expression between stable and unstable segments of plaque obtained from the same patient. METHODS AND RESULTS: Human carotid endarterectomy specimens were segmented and macroscopically classified using a morphological classification system. Two analytical methods, an intraplaque and an interplaque analysis, revealed 170 and 1916 differentially expressed genes, respectively using Affymetrix gene chip analysis. A total of 115 genes were identified from both analyses. The differential expression of 27 genes was also confirmed using quantitative-polymerase chain reaction on a larger panel of samples. Eighteen of these genes have not been associated previously with plaque instability, including the metalloproteinase, ADAMDEC1 (approximately 37-fold), retinoic acid receptor responder-1 (approximately 5-fold), and cysteine protease legumain (approximately 3-fold). Matrix metalloproteinase-9 (MMP-9), cathepsin B, and a novel gene, legumain, a potential activator of MMPs and cathepsins, were also confirmed at the protein level. CONCLUSIONS: The differential expression of 18 genes not previously associated with plaque rupture has been confirmed in stable and unstable regions of the same atherosclerotic plaque. These genes may represent novel targets for the treatment of unstable plaque or useful diagnostic markers of plaque instability.