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.

Using two-dimensional ultrasound imaging to examine venous pressure

Ultrasound imaging is being used increasingly to aid in the teaching of human physiology and anatomy. Here we describe how its use can be integrated into the teaching of concepts surrounding venous circulation, specifically 1) venous valves and the muscle pump, 2) the effects of hydrostatic pressure on venous pressure, and 3) central venous pressure. The imaging procedures described are relatively simple but add a dimension that helps deliver the teaching points clearly and is enjoyable for students. They also aid in the link of basic physiology to clinical aspects of venous circulatory physiology.

Aging of the venous valves as a new risk factor for venous thrombosis in the elderly: the BATAVIA study

Essentials Risk of venous thrombosis (VT) related to valve thickness and valvular reflux in unknown. Venous valves and reflux were measured by ultrasonography in cases and controls aged 70+. Risk of VT was associated with increased valve thickness and valvular reflux >1second. Thickening of valves is a generic process: there was no difference between right and left legs.

SUMMARY

Background Increasing age is the strongest risk factor for venous thrombosis (VT). Increasing age has been related to a thickening of the venous valves and a decreased valvular function. The association between valve thickness and the risk of VT is not known. Objectives To assess the association between increased valve thickness and valve closure time (VCT) and the risk of VT. Methods Analyses were performed in the BATAVIA study, including 70 cases aged 70 + with a first VT and 96 controls. We performed an ultrasound examination of the valves in the popliteal veins. The valves were imaged with a 9 MHz linear probe using B-mode ultrasonography. VCT was measured as an indicator for valve function using an automatic inflatable cuff. To estimate the risk of VT, valve thickness was dichotomized at the 90th percentile as measured in controls and VCT was dichotomized at 1 s. Results Mean valve thickness of controls was similar in the left (0.36 mm, 95% CI 0.34-0.37) and right (0.36 mm, 95% CI 0.35-0.38) leg. In 45 cases a valve was observed in the contralateral leg with a mean valve thickness of 0.39 mm (95% CI 0.36-0.42). Cases had an increased valve thickness compared with controls: mean difference 0.028 mm (95%CI 0.001-0.055). Valve thickness > 90th percentile increased the risk of VT 2.9-fold. Mean VCT in controls was 0.38 s, in contralateral leg of cases 0.58 s. VCT > 1 s increased the risk of VT 2.8-fold (95% CI 0.8-10.4). Conclusions Risk of VT was associated with increased valve thickness and valvular reflux of > 1 s.

[Functional assessment of primary lesion of the great saphenous vein when deciding upon stripping]

The purpose of the study was to examine a possibility of functional assessment of the great saphenous vein (GSV) with the help of a day orthostatic loading test for prognosis of restoration of the function of the GSV afterremoving its varicose tributaries in patients with primary varicose veins. Our prospective study included a total of sixty-five 29-to-53-year-old patients (15 men and 50 women, mean age - 36.7 years). The total number of the lower limb examined amounted to 87. All patients underwent ultrasonographic examination (duplex scanning) prior to operation, 1 and 12 months thereafter. The study was carried out using a day orthostatic loading test consisting in duplex scanning performed twice during 24 hours: in the evening after 18:00 hours and in the morning before 10:00 hours after a good night's rest. It was demonstrated that the day orthostatic loading test characterized the degree of preservation of the muscular-tonic properties of the GSV, making it possible to predict reversibility of reflux along it after removing the varicose tributaries, hence it may be used as a criterion for individualization of the choice of the scope of surgical intervention. A high orthostatic gradient prior to operation suggests preservation of the potential of the muscular-tonic function of the GSV; its decrease after surgery demonstrates reduction of the volemic loading on the GSV.

[Method of preventive ultrasound diagnosis of venous thrombosis]

AIM

The purpose of the study was to work out a method of preventive diagnosis of venous thromboses by means of ultrasonographic duplex scanning (USDS).

PATIENTS AND METHODS

A total of 306 people were examined. Of these, 146 patients presented with acute venous thrombosis, 108 subjects suffered from varicose veins, and 52 were apparently healthy people composing the control group. All those enrolled into the study were examined by means of USDS, with the D-dimer level determined.

RESULTS

The obtained findings made it possible to discover and duly describe an ultrasonographic phenomenon of the presence of echo-positive inclusions in the zone of valvular sinuses, which was called the phenomenon of spontaneous echo contrast (SEC). This was followed by working out a classification of this phenomenon, describing two degrees thereof. Degree 1 SEC reflects the fact that the area of valvular sinuses is the most thrombogenic zone. Degree 2 SEC is characterised as a pathological, being simultaneously pre-thrombotic, condition and may serve as one of the earliest predictors of the development of venous thrombosis. A close correlation was established between the degree 2 SEC phenomenon, the presence of venous thrombosis and the values of the D-dimer level (r=0.89, p<0.01).

CONCLUSION

Ultrasonographic examination of valvular sinuses is a simple, readily available and reproducible method of screening and may thus be used for preventive diagnosis of acute venous thromboses. The findings of this study make it possible to form risk groups by the development of deep vein thrombosis, as well as to initiate timely measures on prevention of the pathology concerned.

Ultrastructure of internal jugular vein defective valves

OBJECTIVES

To study the ultrastructure of intraluminal defects found in the internal jugular vein by using a scanning electron microscopy.

METHODS

Using a scanning electron microscopy, intraluminal septa and/or defective valves blocking the flow in the distal internal jugular vein of seven patients were studied together with the adjacent wall and compared with control specimen.

RESULTS

The internal jugular veins' wall showed a significant derangement of the endothelial layer as compared to controls. Surprisingly, no endothelial cells were found in the defective cusps, and the surface of the structure is covered by a fibro-reticular lamina.

CONCLUSIONS

Although the lack of endothelial cells in the internal jugular vein intraluminal obstacles is a further abnormality found in course of chronic cerebrospinal venous insufficiency, our investigation cannot clarify whether this finding is primary or caused by progressive loss of endothelium in relation to altered haemodynamic forces and/or to a past post-thrombotic/inflammatory remodelling.

Severity of chronic venous disease and anatomic distribution of valvular incompetence

AIM

The aim of the study was to examine the association between anatomical patterns of valvular incompetence and the severity of venous insufficiency in patients with chronic venous disease.

METHODS

A total of 211 consecutive patients (70% females) were referred from the vascular clinic to undergo a Doppler ultrasound examination. The extent and anatomical pattern of valvular incompetence was noted using CEAP criteria. Clinical classes C1-6 for each patient were expressed as a string of binary digits and translated into a clinical ordinal score. In this way, higher grade signs were not obscuring lower grade signs and non-parametric analysis could include a wider range of clinical data.

RESULTS

Varicose veins were the main complaint in 33% of the patients. 54% had at least one incompetent deep vein, 80% had incompetent perforators. Clinical severity increased with age, but was not related with gender. The presence of deep venous incompetence did not account for significant increase in signs. Superficial incompetence, especially if involving two or more segments, was most commonly seen in patients with severe signs. A linear regression model for clinical ordinal score identified non-saphenous superficial reflux and small saphenous vein reflux as the strongest predictors of clinical severity.

CONCLUSION

CEAP clinical classes can be translated into a clinical ordinal score, which is useful for data analysis. In a group with chronic venous disorders, clinical status is associated mostly with the condition of superficial and calf perforating veins.

Changes in the diameter and valve closure time of leg veins across the menstrual cycle

OBJECTIVES

The purpose of this study was to determine the changes (if any) in the diameter and valve closure time of the lower limb veins in healthy young nulliparous women at different phases of the menstrual cycle.

METHODS

Fifty-three young nulliparous women were asked to undergo clinical evaluations and duplex ultrasound examinations of both lower limb veins to monitor changes in the vein diameter and valve closure time at different phases of their menstrual cycles. The vein diameter on B-mode imaging and valve closure time on pulsed Doppler tracing were calculated at days 1 to 4, 14 to 16, and 25 to 28 of the menstrual cycle. Freidman and related samples Wilcoxon signed rank tests were used to determine time-related changes in venous function.

RESULTS

The volunteers' mean age ± SD was 20.60 ± 1.90 years, and their mean body mass index was 23.90 ± 4.90 kg/m(2). There was a gradual increase in the vein diameter and valve closure time at the specified phases of the menstrual cycle. Friedman and related samples Wilcoxon signed rank tests for venous segment diameter and valve closure time changes between the different phases of the menstrual cycle were performed and showed statistical significance for each venous segment within each limb (P = .003-.025). Also, when adjusted for body mass index, statistical significance existed for the same venous segments in the same limbs (P =.001-.049). There was no statistical significance for the same venous segments at the same phase of the menstrual cycle between limbs (related samples Wilcoxon signed rank test: P =.079-.97).

CONCLUSIONS

During the menstrual cycle, the lower limb veins show an increase in their diameter and valve closure time. These changes are probably mediated by the female sex hormones.

[Ten years of endovenous ablation - achievements, failures and future]

Endovenous ablation of varicose veins is a very frequent treatment method which has more or less replaced the classic stripping method. It has its limitations, advantages as well as disadvantages. The authors present a summarizing article and their own experience with these methods. Histology examinations performed prove differences in the reaction of the endothelium to the individual types of endovenous therapy. Causes of varicose veins treatment failures are discussed.

Velocity field measurements of valvular blood flow in a human superficial vein using high-frequency ultrasound speckle image velocimetry

This study aims to investigate the blood flow around the perivalvular area in a human superficial vein using high-frequency ultrasound (HFUS) speckle image velocimetry. HFUS B-mode images were captured from the superficial veins of human lower extremity with a 35-MHz transducer. To measure the instantaneous velocity fields of blood flow, a cross-correlation particle image velocimetry (PIV) algorithm was applied to two B-mode images that were captured consecutively. The echo speckles of red blood cells (RBCs) were used as flow tracers. In the vicinity of the venous valve, the opening and closing motions of valve cusps were simultaneously visualized with the phasic variation of velocity fields. Large-scale vortices were observed behind the sinus pockets while the main bloodstream was directed proximally. This measurement technique combining PIV algorithm and HFUS B-mode imaging was found to be unique and useful for investigating the hemodynamic characteristics of blood flow in the perivalvular area and for diagnosing venous insufficiency and valve abnormality in superficial blood vessels.

The valvular segment of the lower limbs venous system: anatomical, physiological and physiopathological aspects

The valvular segment is a distinct venous structure, which, from a morphological point of view, is comprised of the following components: the valvular insertion, the valvular gorge entrance orifice, the valvular defile, the valvular gorge exit orifice, the valvular sinus. Endoscopic and echo Doppler examinations are used to identify the normal and the pathological morphology of the valvular segment, and the hemodynamic phenomena occurring at this level. Cusps' integrity and size as well as valvular dynamics are key elements directly involved in shaping the valvular segment in general, and the valvular sinus in particular. The valvular sinus shows an obvious hemodynamic determinism. Valvular segment pathology is the outcome either of a progressively long evolving process initialized by gravitational venous pressure overcharges, or of a rapidly evolving process such as the hemodynamic shock following intense physical efforts. Valvular defunctionalisation implies a different mechanism and a different type of cusp lesion.

Internal jugular vein valves: an assessment of prevalence, morphology and competence by color Doppler echography in 240 healthy subjects

The presence of valves in the head and neck veins is known since classical anatomical dissections. Previous studies have investigated whether jugular veins show constant valves at their ostium and whether these valves are physiologically competent, but, unluckily, these studies have reported conflicting results. Further, recent observations have raised the question whether the incompetence of jugular vein valves might play a pivotal role in neurological disorders related to venous engorgement of the brain. In this study we examined 462 internal jugular veins by using an echocolorodoppler apparatus. In particular, we assessed the presence, morphology and competence of valves at their ostium. Unilateral jugular vein valves were present in 406 cases (88%), mainly on the right side. The most frequently observed morphology (75%, 305 cases) was the two-leaflet valve, and jugular vein valves were incompetent in the huge majority of cases (365 cases, 90%). Our findings confirm the anatomical variability predicted from classical anatomical studies but, unluckily, do not provide additional evidence on the possible role of jugular vein valves in physiology and pathology. Further studies are strongly needed to determine whether these valves actually play an important role in counteracting chest venous pressure and in preventing reflux towards the brain.

[Comparison between canine decellularized venous valve stent combined with endothelial progenitor cells and native venous valve on venous valve closure mechanism in normal physiological conditions]

OBJECTIVE

To compare canine decellularized venous valve stent combining endothelial progenitor cells (EPC) with native venous valve in terms of venous valve closure mechanism in normal physiological conditions.

METHODS

Thirty-six male hybrid dogs weighing 15-18 kg were used. The left femoral vein with valve from 12 dogs was harvested to prepare decellularized valved venous stent combined with EPC. The rest 24 dogs were randomly divided into the experimental group and the control group (n=12 per group). In the experimental group, EPC obtained from the bone marrow through in vitro amplification were cultured, the cells at passage 3 (5 x 10(6) cells/mL) were seeded on the stent, and the general and HE staining observations were performed before and after the seeding of the cells. In the experimental group, allogenic decellularized valved venous stent combined with EPC was transplanted to the left femoral vein region, while in the control group, the autogenous vein venous valve was implanted in situ. Color Doppler Ultrasound exam was performed 4 weeks after transplantation to compare the direction and velocity of blood flow in the distal and proximal end of the valve, and the changes of vein diameter in the valve sinus before and after the closure of venous valve when the dogs changed from supine position to reverse trendelenburg position.

RESULTS

General and HE staining observations before and after cell seeding: the decellularized valved venous stent maintained its fiber and collagen structure, and the EPC were planted on the decellularized stent successfully through bioreactor. During the period from the reverse trendelenburg position to the starting point for the closure of the valve, the reverse flow of blood occurred in the experimental group with the velocity of (1.4 +/- 0.3) cm/s; while in the control group, there was no reverse flow of blood, but the peak flow rate was decreased from (21.3 +/- 2.1) cm/s to (18.2 +/- 3.3) cm/s. In the control group, the active period of valve, the starting point for the closure of the valve, and the time between the beginning of closure and the complete closure was (918 +/- 46), (712 +/- 48), and (154 +/- 29) ms, respectively; while in the experimental group, it was (989 +/- 53), (785 +/- 43), and (223 +/- 29) ms, respectively. There was significant difference between two groups (P < 0.05). After the complete closure of valve, no reverse flow of blood occurred in two groups. The vein diameter in the valve sinus of the experimental and the control group after the valve closure was increased by 116.8% +/- 2.0% and 118.5% +/- 2.2%, respectively, when compared with the value before valve closure (P > 0.05).

CONCLUSION

Canine decellularized venous valve stent combined with EPC is remarkably different from natural venous valve in terms of the valve closure mechanism in physiological condition. The former relies on the reverse flow of blood and the latter is related to the decreased velocity of blood flow and the increased pressure of vein in the venous sinus segment.

Eustachian valve interfering with transcatheter closure of patent foramen ovale

A prominent Eustachian valve (EV) is a common finding in patients with a patent foramen ovale (PFO). Its presence might compromise transcatheter closure of the PFO.

Visualization of the azygos arch valves on multidetector-row computed tomography

To evaluate the frequency and appearance of the azygos arch valves on chest examinations using multidetector-row computed tomography (MDCT), we retrospectively reviewed findings from 194 contrast-enhanced MDCT examinations of the chest. Rate of injection of 300 mgI/ml contrast materials was low (2.0 ml/s) and high (3.0 ml/s). Scanning delay was 80 s on examination on low-rate injection of contrast material and 20 s on high-rate injection of contrast material. The presence of residual contrast material in the azygos arch valves and reflux of contrast material into the azygos arch were recorded. The Cochran-Armitage trend test was used to compare the frequency of residual contrast material in the azygos arch valves and reflux of contrast material into the azygos arch in both groups. Of 92 examinations of high-rate injection of contrast material, 63 (68.5%) demonstrated residual contrast material in the azygos arch valves and 71 (77.2%) demonstrated reflux of contrast material into the azygos arch. A significantly higher frequency of reflux of contrast material into the azygos arch and residual contrast material in the azygos arch valves was seen in the high-rate injection group than in the low-rate injection group (P < 0.05). Residual contrast material in the azygos arch valves was demonstrated more frequently when contrast material was administered in the right side of the arm than in the left side of the arm (P < 0.05). Reflux of contrast material into the azygos arch was common in the high-injection-rate group and residual contrast material in the azygos arch valves was far more frequently seen in the high-injection-rate group than in the low-injection-rate group on MDCT.

Giant Eustachian valve and left ventricular systolic dysfunction in a patient with non-dilated amyloid cardiomyopathy

Amyloid cardiomyopathy is characterized by non-dilated thick-walled left ventricular, thickening of interventricular septum and right ventricular free wall, biatrial enlargement associated with granular 'sparkling' appearance of the myocardium. Typically, decreased left ventricular compliance results in abnormal diastolic functions but left ventricular systolic functions are preserved until late in the course of the illness when left ventricle starts to dilate culminating into dilated cardiomyopathy. We present a 77-year-old patient who had typical echocardiographic features of amyloid heart disease, a giant Eustachian valve resembling cor triatriatum dexter and left ventricular systolic dysfunction without associated left ventricular dilatation.