Venous Valve Incompetence Research Articles

Key Regulators of Angiogenesis and Inflammation Are Dysregulated in Patients with Varicose Veins.

Varicose veins (VVs) are the most common manifestation of chronic venous disease (CVD) and appear as abnormally enlarged and tortuous superficial veins. VVs result from functional abnormalities in the venous circulation of the lower extremities, such as venous hypertension, venous valve incompetence, and venous reflux. Previous studies indicate that enhanced angiogenesis and inflammation contribute to the progression and onset of VVs; however, dysregulations in signaling pathways associated with these processes in VVs patients are poorly understood. Therefore, in our study, we aimed to identify key regulators of angiogenesis and inflammation that are dysregulated in patients with VVs. Expression levels of 18 genes were analyzed in peripheral blood mononuclear cells (PBMC) using real-time PCR, as well as plasma levels of 6 proteins were investigated using ELISA. Higher levels of CCL5, PDGFA, VEGFC, TGF-alpha, TGF-beta 1, and VEGF-A, as well as lower levels of VEGFB and VEGF-C, were found to be statistically significant in the VV group compared to the control subjects without VVs. None of the analyzed factors was associated with the venous localization of the varicosities. The presented study identified dysregulations in key angiogenesis- and inflammation-related factors in PBMC and plasma from VVs patients, providing new insight into molecular mechanisms that could contribute to the development of VVs and point out promising candidates for circulatory biomarkers of this disease.

Chronic venous insufficiency and venous leg ulcers: Aetiology, on the pathophysiology-based treatment.

The chronic venous disease covers a wide spectrum of venous disorders that are characterized by severely impaired blood return that primarily affects veins in the lower extremities. Morphological and functional abnormalities of the venous system led to chronic venous insufficiency (CVI), and present as leg heaviness/achiness, edema, telangiectasia, and varices. The term 'chronic venous insufficiency' (CVI) refers to a disease of greater severity. Venous dysfunction is associated with venous hypertension and is associated with venous reflux due to poorly functioning or incompetent venous valves, which ultimately reduces venous return, leading to a cascade of morphological, physiological, and histologic abnormalities such as blood pooling, hypoxia, inflammation, swelling, skin changes (lipodermatosclerosis), and in severe cases, venous leg ulcers (VLU). This review summarizes recent knowledge about the aetiology, risk factors, and pathophysiology of VLU and compared the possibilities of their treatment.

The role of venous intervention for the treatment of patients with venous leg ulceration.

More than 1 million people are estimated to have lower limb venous ulceration in the UK. Such wounds are predominantly caused by sustained venous hypertension, as a result of chronic venous insufficiency, often due to venous valve incompetence or an impaired calf muscle pump. Compression therapy is key to venous leg ulcer management and the majority of nurses are aware of the importance of starting patients on compression therapy as early as possible. However, there appears to be a lack of awareness of the importance of venous assessment and that more patients could benefit from endovenous correction of superficial venous incompetence.

Study on tensile properties of compression SOCKS ankle cut-strips at practical extension

Compression pressure exertion is strongly related to mechanical properties of compression socks deployed with various type of materials and machine adjustments. These socks work on the principle of highest pressure at the ankle and gradually decrease towards the calf portion. Compression socks are used for the prophylaxis and treatment of venous disorders. Venous disorders range from minor asymptomatic incompetence of venous valves to chronic venous ulceration. Current research work contains analysis of the force at practical extension compared to experimental pressure (Ps), the relationship between experimental pressure (Ps), force at practical extension, and tensile indices which include hysteresis (H), tensile resilience (TR), and tensile linearity (TL). Results showed that the force value at practical extension (FL) impart the significant influence on experimental pressure (Ps). It is also portrayed that the tensile indices (W, W′, H, TR, and TL) combined with force at practical and experimental pressure also shown to have contributed significantly to the explanation of experimental pressure (Ps) results. Compression sock tensile characteristics are highly significant and directly related to their productivity, effectiveness, and working life.

Narrative Review of the Pathogenesis of Stasis Dermatitis: An Inflammatory Skin Manifestation of Venous Hypertension.

Stasis dermatitis (SD), also known as venous dermatitis, is a form of inflammatory dermatitis of the lower extremities that typically occurs in older individuals and represents a cutaneous manifestation of venous hypertension. Venous hypertension (also known as sustained ambulatory venous pressure) is most often due to retrograde blood flow, which occurs due to calf muscle pump failure. This failure is most commonly secondary to incompetent venous valves, valve destruction, or obstruction of the venous system. Many of the common symptoms associated with SD are caused by inflammatory processes. This review summarizes the pathogenesis and key role of inflammation in SD by reviewing inflammatory biomarkers associated with SD. The literature was selected though a high-level PubMed search focusing on keywords relating to inflammation associated with SD. Venous reflux at the lower extremities causes venous hypertension, which leads to chronic venous insufficiency. High venous pressure due to venous hypertension promotes the local accumulation and extravasation of inflammatory cells across the vascular endothelium. Leukocyte trapping in the microcirculation and perivascular space is associated with trophic skin changes. Cell adhesion molecules are linked with the perpetuated influx of activated leukocytes into inflammatory sites. Here, inflammatory cells may influence the remodeling of the extracellular matrix by inducing the secretion of proteinases such as matrix metalloproteinases (MMPs). The increased expression of MMPs is associated with the formation of venous leg ulcers and lesions. Phosphodiesterase4 activity has also been shown to be elevated in individuals with inflammatory dermatoses compared to healthy individuals. Because inflammation is a key driver of the signs and symptoms of SD, several of the highlighted biomarkers of inflammation represent potential opportunities to target and interrupt molecular pathways of cutaneous inflammation and, therefore, remediate the signs and symptoms of SD. Understanding the pathogenesis of SD may help clinicians identify drivers of inflammation to use as potential targets for the development of new treatment options.

Modified Palomo Procedure Is an Effective Intervention for Improving Serum Testosterone Levels and Semen Parameters in Patients With Varicocele: A Prospective Study.

A varicocele can be defined as an abnormal venous dilatation and/or tortuosity of the pampiniform plexus. It is generally reported that varicoceles are present in 15% of the general male population and 35% of men as a cause of primary infertilityand in up to 80% of men as a cause of secondary infertility. Differences in venous drainage anatomy between the left and right internal spermatic veins, venous valve incompetence resulting in venous blood reflux, and increased hydrostatic pressure are the most commonly cited theories. Various surgical and non-surgical techniques are in use for treating patients with varicocele. Here we used a modified Palamoprocedure to treat the patients and observed the outcome. A total of 40 patients with varicocele were recruited for the study. A preoperative evaluation, along with serum testosterone levels and semen analysis, was done. A modified Palomotechnique was used to treat varicocele. A postoperative follow-up with serum testosterone levels and semen analysiswas done to observe improvement. The mean (±SD) left testis size, right testis size, testosterone, sperm concentration, sperm vitality and sperm progressive motility were found statistically significantly higher in patients after surgery as compared to patients before surgery (p<0.05). However, there was statistically insignificant mean difference in semen volume between patients before surgery and patients after surgery (p>0.05). Modified Palomoprocedure can be used to treat varicocele with good improvement in serum testosterone levels and semen parameters.

Stasis Dermatitis: An Overview of Its Clinical Presentation, Pathogenesis, and Management.

Stasis dermatitis is a chronic inflammatory skin disease of the lower extremities. It typically occurs in older individuals and is the cutaneous manifestation of venous hypertension caused by venous reflux. Such retrograde venous blood flow is the result of incompetent venous valves, valve destruction, or venous obstruction. Stasis dermatitis is eczematous. The associated impairment of venous valves may cause swelling of the legs, leading to serious conditions including venous ulcerations. Diagnosis can be challenging because of its clinical resemblance to other skin conditions and poor clinical recognition by physicians. The cornerstones of stasis dermatitis treatment are compression therapy to ameliorate pain and swelling, topical treatments to alleviate secondary skin changes, and interventional treatment options to correct the underlying causes of venous reflux. Given the central role of inflammation of the lower extremities in driving the cutaneous changes characteristic of stasis dermatitis, new therapeutic approaches that target the inflammation are under clinical evaluation in patients with stasis dermatitis.

Tissue remodelling and increased DNA damage in patients with incompetent valves in chronic venous insufficiency.

Chronic venous insufficiency (CVI), in which blood return to the heart is impaired, is a prevalent condition worldwide. Valve incompetence is a complication of CVI that results in blood reflux, thereby aggravating venous hypertension. While CVI has a complex course and is known to produce alterations in the vein wall, the underlying pathological mechanisms remain unclear. This study examined the presence of DNA damage, pro‐inflammatory cytokines and extracellular matrix remodelling in CVI‐related valve incompetence. One hundred and ten patients with CVI were reviewed and divided into four groups according to age (<50 and ≥50 years) and a clinical diagnosis of venous reflux indicating venous system valve incompetence (R) (n = 81) or no reflux (NR) (n = 29). In vein specimens (greater saphenous vein) from each group, PARP, IL‐17, COL‐I, COL‐III, MMP‐2 and TIMP‐2 expression levels were determined by RT‐qPCR and immunohistochemistry. The younger patients with valve incompetence showed significantly higher PARP, IL‐17, COL‐I, COL‐III, MMP‐2 and reduced TIMP‐2 expression levels and a higher COL‐I/III ratio. Young CVI patients with venous reflux suffer chronic DNA damage, with consequences at both the local tissue and systemic levels, possibly associated with ageing.

Radiofrequency ablation for markedly incompetent perforators versus compression therapy in the management of post-phelebtic venous ulcers: A randomized controlled trial.

Venus ulcers developed mainly due to reflux of incompetent venous valves in perforating veins. In this randomized controlled trial, 119 patients recruited over two years, with post-phelebtic venous leg ulcers, were randomly assigned into one of two groups: either to receive radiofrequency ablation of markedly incompetent perforators (Group A, n = 62 patients) or to receive conventional compression therapy (Group B, n = 57 patients). Follow-up duration required for ulcer healing continued for 24 months post randomization. Statistically significant shorter time to healing (ulcer complete healing or satisfactory clinical improvement) between both groups (56 patients, 90.3% of cases in Group A versus 44 patients 77.2% of cases in Group B) over the follow-up period of 24 months was attained (p = 0.001). Also, significantly different ulcer recurrence was recorded between both groups, 8 patients (12.9%) in Group A versus 19 patients (33.3%) in Group B (p = 0.004). In absence of deep venous obstruction, the monopolar radiofrequency ablation for incompetent perforators is a feasible and effective method that surpasses the traditional compression protocol for incompetent perforator-induced venous ulcers in terms of time required for healing even in the presence of unresolved deep venous valvular reflux.

Prevalence of Varicose Veins Among Secondary Schools' Teachers in Assiut Governorate

Background: Varicose veins are chronic venous disorder described as enlarged, twisted, superficial veins caused by incompetent venous valves. It affects the lower limbs and quality of life of patients negatively. Aim: to determine the prevalence of varicose veins among secondary schools' teachers at Assiut Governorate. Methods: Descriptive - cross sectional research design had been used. The study was conducted at 4 districts which were randomly selected by using simple random sample to select the schools (3 schools in each district). The total number of the study sample was 500 teachers. Tools: - Three tools were used; the first tool was a structured self-administered questionnaire for demographic data, medical history, and risk factors. The second tool Venous Insufficiency Epidemiological and Economic Study – symptoms (VEINES- Sym) questionnaire. The third tool was clinical examination and Arterial color coded duplex scanning. Results: Prevalence of varicose veins among secondary schools' teachers in Assiut Governorate was 25.6%, 62.5% of them are females while 37.5% are males. Conclusion Varicose veins were widely spread among secondary schools' teachers in Assiut Governorate. Recommendations Health education program is very useful to prevent varicose veins and its complications.

Revisiting the anatomical basis of varicocele

Objective: We intended to revisit aetiology and pathogenesis of varicocele. Results: Several theories were proposed as for the aetiology of left sided varicoceles being commoner than right sided varicoceles such as compression of the left testicular vein by the sigmoid colon, high concentration of adrenaline in the left renal vein causing vasospasms of the left testicular vein, presence of a right angle between the left testicular vein and the renal vein, “nutcracker effect” secondary to a compression of the left renal vein between the superior mesenteric artery and the aorta distal to its confluence with left testicular vein, and the presence of incompetent venous valves of the internal spermatic vein draining the left renal vein causing back flow of the blood. However, these theories were challenged in subsequent studies. Recent studies explored the ultrastructural changes of the pampiniform venous plexus in patients with varicoceles. Histological studies identified changes in the connective tissue density, endothelium and smooth muscle arrangement in these veins. However, the causality of these changes is not yet studied extensively. Genetic studies looking at matrix metalloproteinases synthesis and degradation, inflammation, immune dysregulation or alterations of metabolic pathways are necessary to understand pathogenesis of this clinical entity.

Tissue Level Mechanical Properties and Extracellular Matrix Investigation of the Bovine Jugular Venous Valve Tissue.

Jugular venous valve incompetence has no long-term remedy and symptoms of transient global amnesia and/or intracranial hypertension continue to discomfort patients. During this study, we interrogate the synergy of the collagen and elastin microstructure that compose the bi-layer extracellular matrix (ECM) of the jugular venous valve. In this study, we investigate the jugular venous valve and relate it to tissue-level mechanical properties, fibril orientation and fibril composition to improve fundamental knowledge of the jugular venous valves toward the development of bioprosthetic venous valve replacements. Steps include: (1) multi loading biaxial mechanical tests; (2) isolation of the elastin microstructure; (3) imaging of the elastin microstructure; and (4) imaging of the collagen microstructure, including an experimental analysis of crimp. Results from this study show that, during a 3:1 loading ratio (circumferential direction: 900 mN and radial direction: 300 mN), elastin may have the ability to contribute to the circumferential mechanical properties at low strains, for example, shifting the inflection point toward lower strains in comparison to other loading ratios. After isolating the elastin microstructure, light microscopy revealed that the overall elastin orients in the radial direction while forming a crosslinked mesh. Collagen fibers were found undulated, aligning in parallel with neighboring fibers and orienting in the circumferential direction with an interquartile range of −10.38° to 7.58° from the circumferential axis (n = 20). Collagen crimp wavelength and amplitude was found to be 38.46 ± 8.06 µm and 4.51 ± 1.65 µm, respectively (n = 87). Analyzing collagen crimp shows that crimp permits about 12% true strain circumferentially, while straightening of the overall fibers accounts for more. To the best of the authors’ knowledge, this is the first study of the jugular venous valve linking the composition and orientation of the ECM to its mechanical properties and this study will aid in forming a structure-based constitutive model.

Fluid–structure interactions modeling the venous valve

In this study, a fully coupled fluid–structure interaction computational model for a pulsatile flow in the venous valve was developed. An arbitrary Lagrangian–Eulerian formulation is used in the coupled model, considering two domains, specifically the blood flow and the valve leaflets. The effect of the gap width between the valve leaflets (venous valve incompetence) on the valve reverse flow (reflux) has been investigated.

Evaluation of Peak Reflux Velocities with Vector Flow Imaging and Spectral Doppler Ultrasound in Varicose Veins.

Purpose Spectral Doppler ultrasound (SDUS) is used for quantifying reflux in lower extremity varicose veins. The technique is angle-dependent opposed to the new angle-independent Vector Flow Imaging (VFI) method. The aim of this study was to compare peak reflux velocities obtained with VFI and SDUS in patients with chronic venous disease, i. e., pathological retrograde blood flow caused by incompetent venous valves. Materials and Methods 64 patients with chronic venous disease were scanned with VFI and SDUS in the great or the small saphenous vein, and reflux velocities were compared to three assessment tools for chronic venous disease. A flow rig was used to assess the accuracy and precision of the two methods. Results The mean peak reflux velocities differed significantly (VFI: 47.4 cm/s vs. SDUS: 62.0 cm/s, p<0.001). No difference in absolute precision (p=0.18) nor relative precision (p=0.79) was found. No correlation to disease severity, according to assessment tools, was found for peak reflux velocities obtained with either method. In vitro, VFI was more accurate but equally precise when compared to SDUS. Conclusion Both VFI and SDUS detected the pathologic retrograde flow in varicose veins but measured different reflux velocities with equal precision. VFI may play a role in evaluating venous disease in the future.

Retrograde administration of ultrasound-guided endovenous microfoam chemical ablation for the treatment of superficial venous insufficiency

ObjectiveThis study measured patient outcomes among symptomatic patients with superficial chronic venous insufficiency who were treated with retrograde ultrasound-guided polidocanol microfoam 1% in a community setting. MethodsBetween March 2015 and June 2017, 250 symptomatic patients with C2-C6 chronic venous insufficiency received polidocanol microfoam 1% and were followed for 16 ± 7 months. Sixteen of the 250 patients (6.4%) had skin ulcers, and 56 (22.4%) were treated previously with thermal or surgical interventions. All patients underwent a duplex ultrasound venous incompetence study to map perforators and veins to be treated. Incompetent veins were accessed with a micropuncture needle distal to the midthigh perforator, approximately 10 cm above the knee fold. The leg was then elevated 45°. Under ultrasound guidance, the incompetent greater saphenous vein was closed with polidocanol microfoam 1%. A second injection was administered through the same catheter directing the microfoam to flow in a retrograde fashion through the incompetent venous valves to the ankle. ResultsAll patients completed the initial treatment; 55 (22.0%) required planned secondary treatment during the follow-up period for residual venous reflux in the below-knee greater saphenous vein. Complete elimination of venous valvular reflux and symptom improvement was documented in 236 patients (94.4%). Minor adverse events included asymptomatic deep vein thrombi (n = 2), common femoral vein thrombus extension (n = 1), and superficial venous thrombi (n = 4). Of the 16 patients with skin ulcers, 10 were C6 patients and 80% experienced wound closure within 4 weeks of treatment. ConclusionsRetrograde administration of polidocanol microfoam 1% is a safe and effective treatment with important clinical benefit for superficial venous insufficiency in community practice.

Biaxial Mechanical Behavior of Bovine Saphenous Venous Valve Leaflets

Chronic venous disease is caused by chronic venous insufficiency (CVI), which results in significant symptoms such as venous ulcers, ankle eczema, leg swelling, etc. Venous valve incompetence is a major cause of CVI. When the valves of veins in the leg become incompetent (i.e., do not close properly), blood is able to flow backwards (i.e., reflux), which results in blood pooling in the lower extremities, distal venous hypertension, and CVI. Current clinical therapies, such as surgical venous valve reconstruction and bioprosthetic venous valve replacement, are highly invasive and only moderately successful. This is due, in part, to the scanty information available about venous valve leaflet structure and mechanical properties. To date, only one previous study by our research group has reported on the mechanical properties of venous valve leaflet tissue, and specifically in the case of jugular vein valves. In this study, we conducted equibiaxial tensile tests on bovine saphenous vein valve leaflet tissues to better understand their nonlinear, anisotropic mechanical behavior. By stretching the valvular tissues to 60% strain in both the circumferential and radial directions, we generated stress-strain curves for proximal (i.e., those closest to the heart) and distal (i.e., those furthest from the heart) valve leaflets. Histology and collagen assays were also conducted to study corresponding leaflet microstructures and the biochemical properties of the tissues. Results showed: (1) saphenous venous valve tissues possessed overall anisotropic properties. The tissues were stiffer in the circumferential direction than in the radial direction (p<0.01), and (2) saphenous venous valve tissues from the proximal end showed nonlinear isotropic mechanical properties, while those from the distal end showed nonlinear anisotropic mechanical properties. (3) Distal saphenous venous valve tissues appeared to be stiffer than proximal ones in the circumferential direction, p=0.04 (i.e., inter-valvular variability), and (4) the collagen concentration showed a decreasing trend from the proximal to the distal end. This study focuses on highly relevant animal (bovine) tissues to develop test protocols, establish biomechanical structure-function correlations, and to provide data critical to the design of clinical prosthetic venous valves. To the best of the author's knowledge, this is the first study reporting the biaxial mechanical properties of saphenous venous valve leaflet tissues and thus contributes toward refining our collective understanding of valvular tissue biomechanics.

Prediction of saphenofemoral junction incompetence by measurement of great saphenous vein size at the level of femoral condyle

Introduction: Doppler ultrasonography (USG) is the primary modality for diagnosis of superficial venous reflux caused by incompetence of venous valves of the great saphenous vein (GSV) and usually associated with competence of saphenofemoral junction (SFJ). This study is done to know the cutoff value in size of GSV that safely predicts this junction incompetence. Methods: All varicose vein patients during the study period of January–December 2016 were included in the study. The cases underwent Doppler USG of GSV using Siemens Acuson P500 to identify GSV. The diameter of GSV was measured at the level of femoral condyle in standing position and these were compared with SFJ incompetence. Contralateral limbs which were apparently normal were taken as control limbs if there is no evidence of reflux in SFJ. Results: There were 147 patients with 16 cases (9.81%) where bilateral limb was involved making total cases as 163 limbs and controls as 131 limbs. The mean GSV diameter in disease group was 6.05 mm and in control group was 3.19 mm with P < 0.05. Receiver operating characteristic (ROC) curve of size of GSV at the level of knee and prediction of SFJ incompetence had the ideal curve depicting use of some cutoff value. The point with both best sensitivity and specificity lied on 4.95 mm with sensitivity of 82% and specificity of 83%. Conclusion: We recommend 5 mm as the cutoff value for diameter of GSV at the level of femoral condyle which successfully predicts SFJ incompetence.

Biaxial mechanical behavior of bovine saphenous venous valve leaflets.

Chronic venous disease is caused by chronic venous insufficiency (CVI), which results in significant symptoms such as venous ulcers, ankle eczema, leg swelling, etc. Venous valve incompetence is a major cause of CVI. When the valves of veins in the leg become incompetent (i.e., do not close properly), blood is able to flow backwards (i.e., reflux), which results in blood pooling in the lower extremities, distal venous hypertension, and CVI. Current clinical therapies, such as surgical venous valve reconstruction and bioprosthetic venous valve replacement, are highly invasive and only moderately successful. This is due, in part, to the scanty information available about venous valve leaflet structure and mechanical properties. To date, only one previous study by our research group has reported on the mechanical properties of venous valve leaflet tissue, and specifically in the case of jugular vein valves. In this study, we conducted equibiaxial tensile tests on bovine saphenous vein valve leaflet tissues to better understand their nonlinear, anisotropic mechanical behavior. By stretching the valvular tissues to 60% strain in both the circumferential and radial directions, we generated stress-strain curves for proximal (i.e., those closest to the heart) and distal (i.e., those furthest from the heart) valve leaflets. Histology and collagen assays were also conducted to study corresponding leaflet microstructures and the biochemical properties of the tissues. Results showed: (1) saphenous venous valve tissues possessed overall anisotropic properties. The tissues were stiffer in the circumferential direction than in the radial direction (p<0.01), and (2) saphenous venous valve tissues from the proximal end showed nonlinear isotropic mechanical properties, while those from the distal end showed nonlinear anisotropic mechanical properties. (3) Distal saphenous venous valve tissues appeared to be stiffer than proximal ones in the circumferential direction, p=0.04 (i.e., inter-valvular variability), and (4) the collagen concentration showed a decreasing trend from the proximal to the distal end. This study focuses on highly relevant animal (bovine) tissues to develop test protocols, establish biomechanical structure-function correlations, and to provide data critical to the design of clinical prosthetic venous valves. To the best of the author's knowledge, this is the first study reporting the biaxial mechanical properties of saphenous venous valve leaflet tissues and thus contributes toward refining our collective understanding of valvular tissue biomechanics.

Biaxial mechanical properties of bovine jugular venous valve leaflet tissues.

Venous valve incompetence has been implicated in diseases ranging from chronic venous insufficiency (CVI) to intracranial venous hypertension. However, while the mechanical properties of venous valve leaflet tissues are central to CVI biomechanics and mechanobiology, neither stress-strain curves nor tangent moduli have been reported. Here, equibiaxial tensile mechanical tests were conducted to assess the tangent modulus, strength and anisotropy of venous valve leaflet tissues from bovine jugular veins. Valvular tissues were stretched to 60% strain in both the circumferential and radial directions, and leaflet tissue stress-strain curves were generated for proximal and distal valves (i.e., valves closest and furthest from the right heart, respectively). Toward linking mechanical properties to leaflet microstructure and composition, Masson's trichrome and Verhoeff-Van Gieson staining and collagen assays were conducted. Results showed: (1) Proximal bovine jugular vein venous valves tended to be bicuspid (i.e., have two leaflets), while distal valves tended to be tricuspid; (2) leaflet tissues from proximal valves exhibited approximately threefold higher peak tangent moduli in the circumferential direction than in the orthogonal radial direction (i.e., proximal valve leaflet tissues were anisotropic; [Formula: see text]); (3) individual leaflets excised from the same valve apparatus appeared to exhibit different mechanical properties (i.e., intra-valve variability); and (4) leaflets from distal valves exhibited a trend of higher soluble collagen concentrations than proximal ones (i.e., inter-valve variability). To the best of the authors' knowledge, this is the first study reporting biaxial mechanical properties of venous valve leaflet tissues. These results provide a baseline for studying venous valve incompetence at the tissue level and a quantitative basis for prosthetic venous valve design.

Stasis Dermatitis: Pathophysiology, Evaluation, and Management.

Stasis dermatitis commonly occurs in older age. It is caused by venous hypertension resulting from retrograde flow due to incompetent venous valves, valve destruction, or obstruction of the venous system. Further tissue changes arise from an inflammatory process mediated by metalloproteinases, which are up-regulated by ferric ion from extravasated red blood cells. Stasis dermatitis presents initially as poorly demarcated erythematous plaques of the lower legs bilaterally, classically involving the medial malleolus. It is one of the spectrum of cutaneous findings that may result from chronic venous insufficiency. Its mimics include cellulitis, contact dermatitis, and pigmented purpuric dermatoses. Duplex ultrasound is useful in demonstrating venous reflux when the clinical diagnosis of stasis dermatitis is inadequate. Conservative treatment involves the use of compression therapy directed at improving ambulatory venous pressure. Interventional therapy currently includes minimally invasive techniques such as endovenous thermal ablation and ultrasound-guided foam sclerotherapy, which have supplanted the use of open surgical techniques.