Progressive veining during peridotite carbonation: insights from listvenites in Hole BT1B, Samail ophiolite (Oman)

The reaction of serpentinized peridotites with CO2-bearing fluids to listvenite (quartz-carbonate rocks) requires massive fluid flux and significant permeability despite increase in solid volume. Listvenite and serpentinite samples from Hole BT1B of the Oman Drilling Project help to understand mechanisms and feedbacks during vein formation in this process. Samples analyzed in this study contain abundant magnesite veins in closely spaced, parallel sets and younger quartz-rich veins. Cross-cutting relationships suggest that antitaxial, zoned carbonate veins with elongated grains growing from a median zone towards the wall rock are among the earliest structures to form during carbonation of serpentinite. Their bisymmetric chemical zoning of variable Ca and Fe contents, a systematic distribution of SiO2 and Fe-oxide inclusions in these zones, and cross-cutting relations with Fe-oxides and Cr-spinel indicate that they record progress of reaction fronts during replacement of serpentine by carbonate in addition to dilatant vein growth. Euhedral terminations and growth textures of carbonate vein fill together with local dolomite precipitation and voids along the vein – wall rock interface suggest that these antitaxial veins acted as preferred fluid pathways allowing infiltration of CO2-rich fluids necessary for carbonation to progress. Fluid flow was probably further enabled by external tectonic stress, as indicated by closely spaced sets of subparallel carbonate veins. Despite widespread subsequent quartz mineralization in the rock matrix and veins, which most likely caused a reduction in the permeability network, carbonation proceeded to completion in listvenite horizons.

Immobilized Bisphosphonates as Potential Inhibitors of Bioprosthetic Calcification: Effects on Various Xenogeneic Cardiovascular Tissues

Calcification is the major factor limiting the clinical use of bioprostheses. It may be prevented by the immobilization of bisphosphonic compounds (BPs) on the biomaterial. In this study, we assessed the accumulation and structure of calcium phosphate deposits in collagen-rich bovine pericardium (Pe) and elastin-rich porcine aortic wall (Ao) and bovine jugular vein wall (Ve) cross-linked with glutaraldehyde (GA) or diepoxy compound (DE). These tissues were then modified with pamidronic (PAM) acid or 2-(2′-carboxyethylamino)ethylidene-1,1-bisphosphonic (CEABA) acid. Tissue transformations were studied using Fourier-transform infrared spectroscopy. After subcutaneous implantation of the biomaterials in 220 rats, calcification dynamics were examined using atomic absorption spectrophotometry, light microscopy after von Kossa staining, and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy The calcium content in all GA-cross-linked tissues and DE-cross-linked Ao increased to 100–160 mg/g on day 60 after implantation. BPs prevented the accumulation of phosphates on the surface of all materials and most effectively inhibited calcification in GA-cross-linked Ao and DE-cross-linked Pe. PAM containing -OH in the R1 group was more effective than CEABA containing -H in R1. The calcification-inhibitory effect of BPs may be realized through their ability to block nucleation and prevent the growth of hydroxyapatite crystals.

Chronic venous insufficiency after COVID-19: management of edema and pain syndromes

Introduction. COVID-19 infection raises many questions regarding the health condition of patients after they have had COVID-19. The aim of this study is to examine the characteristic symptoms of chronic venous insufficiency in the postcovid period.Materials and methods. The materials that were used for work included the results of studying the medical aid appealability, characteristic symptoms, diagnosis and treatment of symptoms of chronic venous insufficiency in persons who have had the coronavirus infection. 47 patients presented with complaints about deterioration of their condition after they had had COVID-19 over March to September 2021 period. Methods: general clinical examiniation, ultrasound angioscanning of veins of the lower extremities, laboratory coagulation tests.Results and discussion. Before deterioration, calf circumference was measured 22–24 cm at a typical measurement site in most patients (89%), after covid infection it reached 26–27 cm. Varicose veins remained soft, without intravascular formations, edema was often bilateral, asymmetric, pain was described as constant (5–6 VAS scores), patients had prominent signs of lymphostasis. 35 out of 47 people received diosmin-based venotonic drug of Russian manufacture at a dose of 1000 mg/day (one tablet twice a day), the course of treatment lasted one to two months. After that period, the edema subsided in 85% of patients, the severity of pain syndrome significantly reduced (up to 2–3 VAS scores). With regard to chronic venous insufficiency in patients with chronic diseases of lower extremity veins (mostly varicose and post-thrombotic diseases), the significant progress of disease was observed in almost 94% of follow-up cases. Diosmin is the main drug that is prescribed to treat chronic venous insufficiency. The drug has an angioprotective and venotonic effect, reduces the vein wall elasticity, increases venous tone, and decreases venous stasis, reduces capillary permeability and fragility, and increases their resistance, improves microcirculation and lymphatic drainage.Сonclusions. In the postcovid period, clinical symptoms of some chronic diseases occur/worsen, including clinical manifestations of chronic venous insufficiency. The use of Russian diosmin-based drug for the management of edema and pain syndrome is very promising.

Risk Factors for Lead-Related Venous Obstruction: A Study of 2909 Candidates for Lead Extraction

Background: our knowledge of lead-related venous stenosis/occlusion (LRVSO) remains limited and there is still controversy regarding the risk factors for LRVSO. Venography is mandatory before transvenous lead extraction (TLE). Methods: we performed a retrospective analysis of venograms in 2909 patients (39.43% females, average age 66.90 years) who underwent TLE between 2008 and 2021 at high-volume centers. Results: the severity of LRVSO was likely to be dependent on the number of leads in the system (OR = 1.345; p = 0.003), the number of abandoned leads (OR = 1.965; p < 0.001), the presence of coronary sinus leads (OR = 1.184; p = 0.056), male gender (OR = 1.349; p = 0.003) and patient age at first CIED implantation (OR = 1.008; p = 0.021). The presence of permanent atrial fibrillation (OR = 0.666; p < 0.001) and right ventricular diastolic diameter (OR = 0.978; p = 0.006) showed an inverse correlation with the degree of LRVSO. The combined three-model multivariate analysis provided better prediction of LRSVO using the above-mentioned factors than the CHA2DS2-VASc score. Conclusions: the severity of LRVSO is probably dependent on the mechanical impact of the implanted/abandoned leads on the vein wall, therefore the study has demonstrated the central role of system-/procedure-related risk factors. The thrombotic mechanism may be less important, especially long after implantation, and for this reason the combined prediction model for LRVSO in this study was more effective than the CHA2DS2-VASc score.

Volume of surgical intervention in renal cancer, complicated by invasion of tumoral thrombus into venous wall

Objective. To determine the volume of surgical intervention on vena cava inferior in renal cancer, complicated by invasion of tumoral thrombus into the vein wall. Materials and methods. Into the investigation were included 147 patients, suffering renal cancer, complicated by tumoral venous thrombosis, who were treated surgically in the Zakarpattya Regional Clinical Hospital named after Andriy Novak or in the Zakarpattya Antitumoral Centre in 2005 - 2020 yrs. The patients’ age varied from 27 to 79 yrs old, their average age have constituted 58 yrs old. There were 97 (66%) men and 50 (34%) women. The null level of venous spread of tumoral thrombus was diagnosed in 55 (37.4%), І – in 32 (21.8%), ІІ – in 30 (20.4%), ІІІ – in 22 (15.0%), and IV - in 8 (5.4%) patients. The tumor was localized in right kidney in 51 (34.7%) patients. Surgical treatment in all the patients was performed - nephrectomy and various interventions on the vein. Longitudinal resection of the vein was performed in 55 (37.4%), resection with suturing of alloflap - in 5 (3.4%), circular resection with prosthesis “end-to-end” - in 4 (2.7%) patients. In the tumoral thrombus localization, including a renal vein, the uxtaosteum resection was performed in 100% of the patients. Results. Average duration of the operation was 165 (102 - 292) min, average volume of the blood loss - 780 (240 - 2250) ml. Mild and moderate postoperative complications in accordance to classification of Clavien-Dindo (Degree I - II) was registered in 38 (21.8%), and the severe (Degree ІІІ - V) - in 6 (4.1%) patients. Surgical complications of Degree III or complications, which demanded urgent relaparotomy, were not observed. In early postoperative period 1 patient died. General postoperative lethality have constituted 0.7%. In all the patients a laminar blood flow was preserved. In no one patient the prosthesis thrombosis, recurrence of the prosthesis thrombus, recurrence of tumoral venous thrombus or pulmonary thromboembolism. Conclusion. Radical method of surgical treatment of renal cancer, complicated by tumoral thrombosis of vena cava inferior, must include nephrectomy, cavatomy, thrombectomy, various variants of resection and prosthesis of the vein. In the null level of the tumoral thrombus venous spread the performance of uxtaosteum resection of renal vein is obligatory.

Hydraulic expansion facilitates remodeling of arteriovenous fistulas without increasing venous intimal hyperplasia in rabbits

Background An arteriovenous fistula (AVF) is considered essential for chronic hemodialysis. Objective To determine the effects of hydraulic expansion on the intimal hyperplasia of an AVF. Methods We divided 12 healthy male New Zealand white rabbits into a control group (vein without special handling and direct anastomosis with an artery, n = 6) and a hydraulic expansion group (vein dilated by hydraulic pressure before anastomosis, n = 6). Histopathomorphology was examined with hematoxylin and eosin staining and immunohistochemistry. Analysis of covariance (ANCOVA) was used to compare the data between the groups. Results Immediately and 1 day after surgery, the diameter of the fistula vein in rabbits in the hydraulic expansion group was significantly larger than it was in the control group (P = 0.02 and 0.03 respectively), but not on subsequent days. After hydraulic expansion and before construction of the fistula, the wall of vein was noticeably thinner on macroscopic observation, and the anterior and posterior walls were indistinguishable. At 3 weeks after surgery in the hydraulic expansion group, cells in the vein wall were disordered, there were fewer elastic fibers, tissues from the endothelium to tunica externa were less dense, and there was less extracellular matrix than in the control group. Expression of connective tissue growth factor in the hydraulic expansion group was significantly less than that in the control group (P = 0.01). No differences were found in intimal thickness or immunohistochemistry scores for transforming growth factor-β1 between the groups. Conclusion Hydraulic expansion did not increase intimal hyperplasia of an AVF, but facilitates remodeling of AVFs in rabbits.

Investigation of helical strut attached vena cava filter hemodynamic performanc

Hemodynamic performance of the Celect Platinum vena cava filter and the revised forms of it with helical flow inducer strut were studied with computational fluid dynamic software Ansys Fluent 18. The central velocity and shear stress increased but overall flow disturbance has been observed minimal level. Central velocity increases to 9.72% with Celect filter, by the single helical flow inducer strut the rate reaches to 14.69%, and with doubled form it reaches to 19.73%. The filter surface shear rate increases to 8.29% with the single helical flow inducer strut and increases 13.31% with doubled attachment. Increased velocity and shear stress on the filter may eliminate short term thrombus build-up problems by breaking the big size particulates with the high shearing forces. The new struts may also contribute to the ability of the filter to capture smaller clots, as well as to dissolve them from being bigger. Shear stress in the vein wall increases approximately 6.63% with the filter placement. It raises to 8.06% and 9.45% with single and double helical flow inducer strut attachment. Increased vein wall shear may reduce the recirculation and clotting in the vein wall and it may prevent the accumulation of clots. The increased shear stress on the filter may cause the migration problem, design improvements can minimize this risk. Helical flow inducer strut attachment can cause efficacy increase, and the flow are normalized.

A pre-clinical animal study of a novel mechanical-only ablation device treatment for superficial venous disease

Objective Current minimally invasive techniques for ablation in superficial venous reflux are limited to thermal based systems requiring tumescent anesthesia, non-thermal chemical sclerosants and permanent glue implantation. The aim of this feasibility study was to determine the safety and efficacy of a novel mechanical-only ablation (MOA) device called EnVena, in a recognised large animal model with chronic follow up. Methods Venous ablation of six lateral saphenous veins in three sheep was performed using the EnVena device. Luminal patency and vein wall fibrosis were evaluated by histologic analysis at 51 and 89 days. Results All treated veins demonstrated fibrotic occlusion in contiguous segments at 51 and 89 days on histological analysis. From 45 consecutive segments spanning the treatment length across the six treated veins, 26 (57%) were fully occluded, 7 (16%) were impinged or partially occluded and 12 (27%) were open. There were no device related complications during the follow up period. Conclusions A purely mechanical approach to superficial venous ablation demonstrated safety and efficacy in a recognized large animal model based on histological findings.

No difference in the incidence or location of deep venous thrombosis according to use of pharmacological prophylaxis following total knee arthroplasty

Background The incidence and characteristics of deep vein thrombosis (DVT) following total knee arthroplasty (TKA) without pharmacologic prophylaxis have not been fully investigated. This study aimed to determine whether there are any differences in the incidence, location, and characteristics of DVT following TKA with pharmacologic prophylaxis and without pharmacologic prophylaxis. Methods A total of 156 knees were retrospectively evaluated for DVT following TKA by duplex ultrasound on postoperative day 7, after excluding 60 knees from 216 consecutive knees because of antiplatelet or anticoagulant use before surgery, history of venous thromboembolism, or bleeding risk. The 156 knees included in the analysis were divided into two groups: with pharmacologic prophylaxis (n = 79) and without pharmacologic prophylaxis (n = 77). Results The overall incidence of DVT was 34% (54/156 knees). DVT was detected in 31.6% of knees with pharmacologic prophylaxis and in 37.6% of knees without pharmacologic prophylaxis; the difference was not statistically significant. Soleal vein thrombus was observed in 74.6% of the knees with DVT and non-floating thrombus was observed in 98.7%. There were no obvious between-group differences in thrombus characteristics such as compressibility, echogenicity, mean vein diameter, and whether the thrombus was attached to the vein wall or free-floating. Conclusions No differences were found in the incidence, location, or characteristics of DVT following TKA with or without pharmacological prophylaxis.