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PubMedDate not supplied

In vitro testing of venous valves.

The need to test prosthetic venous valves led to the design of a hydraulic mock circuit that reliably mimics natural venous flow. Components of this system simulate calf muscle pump and thoracoabdominal suction pump action. Flow and pressures are serially measured along the circuit. Valve function can be observed and videotaped. Evaluation of biologic venous valves provides visual and quantitative assessment of venous valve function with respect to tissue processing, valve design, and implantation technique. Further improvement in this system in terms of more compliance and less rigidity of components is being pursued.

Blood Vessel Prosthesis↗
PubMed1988

Repair of incompetent venous valves: a new technique.

Current techniques for treating chronic venous disease caused by venous valve incompetence all have deficiencies. A need exists for a simple technique to restore competence to the diseased valves at multiple sites in the venous system. The Venocuff is an implantable device developed to restore venous valve competence by reducing the vein circumference. Two animal models are described that are useful in the study of venous valve incompetence; the device was tested in these two models in the jugular vein of sheep. The first model was of naturally incompetent valves. The device was implanted around 11 completely incompetent and seven partially incompetent valves in 18 veins of 11 sheep. After implantation competence was restored or improved in all valves. The second model made use of an arteriovenous fistula to produce incompetence in the jugular vein in four sheep. The implant increased the pressure difference across the valve from 16 to 68 mm Hg. The Venocuff implant was thus effective at restoring valvular competence in the two animal models studied. There is evidence that valvular incompetence in these models and the results observed may be applicable in some cases of chronic venous disease in humans.

Animals↗
PubMed1998

A morphological study on human lingual venous valves.

This study deals with the appearance, function and pathophysiological action of the lingual venous valve in the design of surgical tongue flaps and in analyzing inspection of the tongue. Thirty two adult cadavers were studied, of which 7 were corrosive cast specimens. The lingual v. is well supplied with venous valves which may be divided into 3 types morphologically: hemispherical, spherical, and hanging spherical. Venous valves are classified according to their structures: bivalves, monovalves, and venous cristae. The abundant venous valves of the tongue effectively prevent reflux of blood. Various factors that influence venous blood reflux in the head and neck can be observed, analysed and judged by inspection of the tongue; the design of the pedicle and the anastomotic position of tongue flap should comply with the positions and orientations of its venous valves.

Adult↗
PubMed2002

The mechanism of venous valve closure in normal physiologic conditions.

PURPOSE: The purpose of this investigation was to study the mechanism of venous valve closure in physiologic conditions in situ, particularly the clarification of the role of reversed flow through the valve in the closure of the valve cusps. A second purpose was the study of temporal relations between movements of the valve cusps, changes in geometry of venous sinus, and blood flow. METHODS: Twelve healthy volunteers underwent examination with duplex ultrasound scanning. The time relationship between the flow and venous valve movements was analyzed on the basis of real time ultrasound scan records of the saphenofemoral junction. The size and shape of the common femoral vein and the proximal greater saphenous vein were measured with a planimeter. RESULTS: Reverse flow below the valve was registered in only one of the 12 studied subjects. The maximum peak velocity of the reverse flow in this case was 0.8 cm/s and the duration was 0.2 seconds. The reverse flow was registered just before and just after valve closure. The mean duration of the outflow wave below the valve was 816 +/- 57 ms, which was not significantly different from the time of the valve cycle (819 +/- 55 ms; P =.864). The closure of the valve coincided with the decrease of the flow velocities. The first detectable movement of the valve cusps occurred 108 +/- 21 ms after the beginning of the flow deceleration. The mean time interval from the first cusp movement to the complete closure of the valve was 139 +/- 51 ms. Both the size and the shape of the sinus changed during the valve cycle. The size of the sinus increased as much as 127% of the baseline value (1.79 +/- 0.25 cm at baseline; 2.27 +/- 0.23 cm maximum; P =.02), and it became more spheric in shape. The changes in size and shape of the sinus coincided with the movements of the valve cusps. The first detectable change in the sinus size occurred 80 +/- 30 ms after the first detectable movement of the cusps toward closure. CONCLUSION: Reverse flow through the valve is not necessary for the closure of the venous valve. The closure of the venous valve coincides with the decrease of the flow velocities and the ballooning of the sinus (increase of size and the curvature of the valve sinus).

Blood Flow Velocity↗
PubMed1988

Early experimental experience with a surgically created, totally autogenous venous valve: a preliminary report.

A surgically created, totally autogenous venous valve has been devised that holds potential for the treatment of venous insufficiency. Valves were constructed from 2.7 cm long segments of canine external jugular veins. Through the use of intimal separation, folding, and suturing techniques, thin, pliable valves with an intimal lining were constructed and interposed in the canine superficial femoral vein. Fifteen valves were implanted in three groups of dogs. In group I (six dogs) the valves were immediately removed after implantation and subjected to various levels of hydrostatic pressure. In group 2 (six dogs) valves were removed after 1 week and examined for patency and competency. Group 3 animals (three dogs) were anticoagulated with subcutaneously administered heparin from implantation to removal at 7, 9, and 13 days. In group 1 valves were found to open at less than 3 cm of water and remain competent at 55 cm of water. Two of these valves subjected to 300 mm Hg pressure also remained competent. In the six group 2 dogs, two valves remained patent and competent, whereas four valves were patent but incompetent as a result of thrombus that prevented valve closure. In group 3 all valves were patent and competent at 7, 9, and 13 days after implantation. An autogenous venous valve that opens at physiologic pressures and remains competent at high pressures can be surgically created. The ability to remain competent at high pressures may give this valve an advantage over the repaired, transposed, or transplanted native venous valve in the treatment of chronic venous valvular insufficiency.

Animals↗
PubMed2003

Intermediate to long-term results of repairing incompetent multiple deep venous valves using external valvular stenting.

INTRODUCTION: Chronic venous insufficiency is a major cause of morbidity in the community. The purpose of the present study was to assess the efficacy and safety of repairing multiple deep venous valves with an External Valvular Stent. METHODS: Forty-two limbs with chronic venous disease were operated on between 1987 and 1991. The patients included in the present series have now had more than 5 years of follow up (mean: 7.9 years; range: 5.4-11.9 years). Most patients had primary deep venous incompetence. There were 125 valve repairs out of 146 venographically suitable valves primarily in the superficial femoral and popliteal veins (2.98 per limb). Follow up was incomplete because of the duration of the trial. RESULTS: Following surgery ulcer areas decreased from a mean preoperative value of 12.9 cm2 to 1.2 cm2 at 86 months with almost 80% of the ulcers healed. All symptoms, pain, swelling, cramps and pigmentation were improved at a statistically significant level. The 90% infrared photoplethysmography recovery time almost doubled from 6.7 s preoperatively to 12.4 s at 36 months and were unchanged in the long term. Venous pressures were only significant at 12 months post implantation. Using multivariant analysis, the number of stents implanted was statistically associated with an increased number of ulcers healing. The site of venous valve repairs seems to be irrelevant to all of the variables. CONCLUSION: Multiple deep venous valve repairs are appropriate and the best form of treatment for specifically selected individuals with primary deep venous incompetence.

Adult↗
PubMed2000

Venous valve station changes in "primary" and postthrombotic reflux: an analysis of 149 cases.

The purpose of this study was to analyze valve station changes noted during venous valve reconstruction and the associated outcome. One hundred and forty-nine valve reconstructions were available for analysis at the time of surgical exploration; the venous valve was graded according to valve station changes (VS grades) from zero through six. Ascending venography was analyzed by a similar grading system and the two methods were compared. The results of this analysis showed that valve station wall changes are frequently present in patients with deep venous reflux and pose technical challenges during valve reconstruction; the outcome, however, appears unaffected. Grade 0 to 1 valve station changes are predominantly due to "primary" reflux, with an occasional instance of postthrombotic etiology. Grade 2 or 3 valve station changes are roughly evenly divided between phlebosclerosis of primary reflux and postthrombotic etiologies. The mechanism of onset of reflux with preservation of valve cusps in the latter group of postthrombotic cases is probably different from currently accepted theories of evolution of postthrombotic changes. Postthrombotic valve damage is variable, and the valve station anatomy may be sufficiently preserved in some patients to allow direct valve repair.

Endothelium, Vascular↗
PubMed2004

Micro-venous valves in the superficial veins of the human lower limb.

It is commonly believed that venous valves are not present in veins smaller than 2 mm in diameter. Venous valves, however, have been identified recently in small veins in several regions of the body. This study was undertaken to determine the size distribution of venous valves in the human lower limb micro-venous circulation. Vascular casts were made from six adult lower limbs and the sampled areas were viewed by scanning electron microscopy. In total, 2,376 valves were identified from 410 cm(3) of subcutaneous tissue. The vast majority (94%) of the valves were in veins less than 300 microm in luminal diameter, with 65% of the valves present in venous channels less than 100 microm in luminal diameter. The smallest valves identified were present in venous channels 18 microm in diameter. All valves were bicuspid and often associated with a tributary. Endothelial cells on the vein wall not associated with a valve were fusiform and arranged parallel to the long axis of the vessel, however, the endothelial cells on the luminal and valve sinus surfaces of the cusp were more polyhedral in shape and showed no obvious pattern of alignment. This study provides direct evidence to show that small superficial veins of the human lower limb do contain abundant venous valves and, for the first time, shows that the majority of these valves are present within venous channels less than 100 microm in luminal diameter.

Aged↗
PubMed1999

[External valvuloplasty for deep venous valve insufficiency of legs].

OBJECTIVE: To study and evaluate the therapeutic effects of external valvuloplasty for deep venous valve insufficiency of the legs. METHODS: External valvuloplasty of the femoral vein valve was performed in 26 patients (37 legs) with deep venous valve insufficiency of the legs. Among them, 12 were male and 14 were female. These patients ranged in age from 16 to 69 years (x +/- s, 50.8 +/- 10.0). External valvuloplasty of the first pair of the superficial femoral vein valve was carried out in all the legs. External valvuloplasty of the second pair of the superficial femoral vein valve was added in 7 legs and valvuloplasty of the common femoral vein valve in 6 legs. RESULTS: Venous claudication, swelling, aching disappeared in 81.1% patients (30/37), obviously improved in 18.9% (7/37) and varicose veins disappeared in all legs. Ulcer healing was seen in 7/9 patients. Deep venous valve sufficiency was demonstrated in 89.2% patients (33/37), and reflux I degrees - II degrees in 4 legs by color Doppler. CONCLUSIONS: External valvuloplasty is effective in treating deep venous valve insufficiency of the legs.

Adolescent↗
PubMed1999

External valvuloplasty technique in deep venous valve insufficiency of the lower limbs.

OBJECTIVE: To evaluate the therapeutic effects of external valvuloplasty technique in deep venous valve insufficiency of the lower limbs. METHODS: External valvuloplasty of the femoral vein valve was performed in 30 patients(41 limbs) with deep venous valve insufficiency of the lower limbs. The patients ranged in age from 16 to 69 years (mean +/- s, 50.8 +/- 9.2). External valvuloplasty of the first pair of superficial femoral vein valve was carried out in all limbs. External valvuloplasty of the second pair of superficial femoral vein valve was added in 7 limbs and valvuloplasty of the common femoral vein valve in 6 limbs. RESULTS: Venous claudication, swelling, aching disappeared in 78.0% limbs (32), obvious improvement was seen in 22.0% (9), and varicosis disappeared in all limbs. Ulcer healing was observed in 80% (8/10) limbs. Deep venous valve sufficiency was shown in 90.2% limbs, and reflux I degree-II degree in 4 by color Doppler. CONCLUSION: External valvuloplasty is an effective method to treat deep venous valve insufficiency of the lower limbs.

Adolescent↗
PubMed2006

A new ultrasonographic technique for diagnosing deep venous insufficiency--imaging and functional evaluation of venous valves by ultrasonography with improved resolution.

This is to demonstrate a new 2D-ultrasonographic technique which enabled clear resolution of deformed valves, visualization of venous reflux and quantitation of valve incompetence. In a 59-year-old Japanese female patient, ultrasonography was done using Aplio, Toshiba Medical Systems Co., Japan, equipped with 8 MHz linear probe capable of differential tissue harmonic imaging to diagnose the cause of her leg edema. Venous ultrasonography using this device at the popliteal venous valve in this patient demonstrated clear view of deformed venous valve and valve separation at one end of valvular agger while the other part of the valve is closed. Color Doppler failed to show venous reflux due to its low velocity. However, the appearance and disappearance of a thrombus-like echo could be imaged using 2D-ultrasonography. In addition, we were able to demonstrate the time-course change of valve opening and closing, and quantitate the valve incompetence using M-mode ultrasonography.

Edema↗
PubMed1992

Effect of venous valves on grafts for coronary artery bypass.

The effect of venous valves on blood flow and patency in grafts of the long saphenous vein for coronary artery bypass is examined. Our experimental model involved both diastolic-predominant blood flow and transient systolic regurgitation, and the waveform was similar to that of in vivo coronary circulation. In this model, blood flow was assessed in the presence or absence of venous valves. It was found that coronary artery blood flow was significantly greater in the presence of venous valves. Angioendoscopy showed that the movement of the graft valves was strong and rhythmic. It seems that valve preservation may be desirable in grafts for coronary artery bypass.

Angiography↗
PubMed1999

A multicenter, phase I evaluation of cryopreserved venous valve allografts for the treatment of chronic deep venous insufficiency.

PURPOSE: A phase I feasibility study was conducted to determine whether cryopreserved venous valved segments would remain patent/competent in a short-term period (6 months). METHODS: The target group consisted of 10 patients (C(4-6), E, A(D), P(R)). The exclusion criteria included untreated superficial/perforator venous disease, significant venous or arterial obstruction, hypercoagulability or coagulopathy, and significant preexisting medical conditions. Required preoperative tests were venous duplex, ascending/descending venography, and a physiologic study (eg, APG, blood typing, an ankle/brachial index, and if post-thrombotic, a hypercoagulability work-up). A single-valve transplant was placed below all reflux, aided by anticoagulation with or without a distal arteriovenous fistula. Postoperative assessment included duplex scanning/clinical examination (at 1, 3, and 6 months), descending venogram (at 1 month), and physiologic study (at 1 and 6 months). The primary end point was valve patency/competence, with clinical outcome as a secondary end point. Adverse events were recorded. RESULTS: After eliminating protocol violations, nine patients with superficial femoral (5) or popliteal (4) vein valve transplants were studied. Six-month actuarial results show a patency rate of 67% +/- 16% and 78% +/- 13%, respectively, a primary and secondary competency rate of 56% +/- 17% and 67% +/- 16%, respectively, and a 100% patient survival rate. Clinical outcome averaged 1.1, with healing and/or freedom from ulcer recurrence, in six of nine patients. A postoperative risk of seroma formation (3) and cellulitis (1) exists. CONCLUSION: In patients with few remaining therapeutic options, one can achieve a 6-month assisted patency and competency rate of 78% and 67%, respectively, with an improved clinical outcome.

Actuarial Analysis↗
PubMed1991

In situ venous valve construction.

A technique of in situ deep venous valve construction based on vein wall intussusception is described. The technique has been used to construct a size-matched, autogenous valve in the femoral vein of the dog. Forty-one valves have been constructed. Immediately after construction, all 41 were patent at ascending phlebography and Harvey's test showed them to be competent. Descending phlebography demonstrated competence in 38 valves. Hydrostatic testing was performed on 27 valves in the vertical position at pressure gradients in the range 0.2-250 cmH2O. Of these, 24 valves were fully competent. Six valves were studied at intervals between 1 and 112 days after construction. All six were competent by Harvey's test and five were competent at descending phlebography. There was no evidence of thrombosis in any valve. This technique may be suitable for replacement of deep venous valves in patients with the calf pump failure syndrome caused by deep venous reflux.

Animals↗
PubMed2003

Percutaneous prosthetic venous valves: current state and possible applications.

The small-intestinal submucosa square-stent bicuspid venous valve has shown the most promising results of all of the artificial venous valves developed. In long-term experimental studies in sheep, 25 valves were placed into the jugular veins and 88% exhibited good function, whereas 12% had decreased function because of valve tilting. Only 4% had partial thrombosis in the tilted valve. Valves also were placed in 3 patients. The bicuspid venous valves remained patent without thrombosis or other complications. Proper sizing and proper placement of the valves was critical to their function. The valve construction needs to be improved to prevent occasional tilting during their deployment.

Adult↗
PubMed1997

[Anatomic and functional features of venous valves].

The comparison of the venous system in the human organism, and in particular the venous valves of the lower limbs, with studies conducted in animal models helped us to understand better the mechanisms involved in adapting to the upright position and walking. We examined work conducted in several species from the horse to the dog, especially in animals who often take on an upright position such as the chimpanzee and the kangouroo, in search for structures comparable to those in man. Different types of valves can be described in man: flotting valves (bicuspid, pigeon nest valves); reinforced valves (mid-thigh); reinforcing valves (periarticular zone in the knee); finally, "flat" valves which are highly resistant formations but with little anti-back flow action. We also describe valvular structures with muscle cells found in the plantar aspect of the foot and the veins of the quadriceps muscle, these valves may have an active hematopropulsive action (Bassi). These results allowed us to identify certain common points between the structures observed in the posterior legs of certain animals and to propose models for investigating venous diseases.

Adaptation, Physiological↗
PubMed1995

Deep venous valve reconstruction.

The place of deep venous valve reconstruction in the surgical management of the patient with chronic venous insufficiency has become clearer with collected experience over the past 25 years. The reasons to perform surgery in chronic venous disease and the specific rationale for deep venous repair are contrasted with the management of the same patient by medical means. A new classification of chronic venous disease has been developed and provides the basis for a more objective understanding of specific entities in the entire field of chronic venous symptoms. The requirements for diagnosis before reconstructive surgery are stringent and a diagnostic algorithm is discussed in the selection of candidates for deep venous reconstruction. The multiple surgical techniques for deep venous reconstruction include internal intravenous direct valve repair and extravenous tightening of the vein wall around the valve cusp. The results of valve repair for primary valve incompetence are discussed in terms of long-term clinical results, long-term imaging results and long-term physiologic results as reflected by venous pressure examinations. It is becoming increasingly clear with the passage of time and the sharpening of our diagnostic skills that reflux is the dominant cause of chronic venous insufficiency. The ability of surgical procedures to decrease reflux in a diseased extremity can be used to restore patients to their normal way of life free of pain, swelling and ulceration and, in the ideal case, free of the need for elastic support.

Chronic Disease↗
PubMed1998

[Treatment of venous reflux disease of the leg by deep-venous valve reconstruction].

UNLABELLED: In order to evaluate the effect and indication of three kinds of deep-venous valve reconstruction surgery, 62 cases with venous reflux disease of the leg had been treated from Jan. 1992 to Jun. 1996. All the patients had varicose vein and tingle in varying degrees, besides swelling in 30 cases, pigmentation in 28 cases, ulcer in 14 cases. The course of disease ranged from 1 to 30 years (averaged 14.6 years). METHOD: 14 cases were treated by ringing of the superficial femoral venous 1st valve, 1 case was treated by repairing of the superficial femoral venous 1st valve, 47 cases were treated by formation of substitute valve outside the popliteal vein. The symptoms of all the patients were alleviated with an average follow-up for 20 months. Fourteen cases with ulcer were healed compeletely and no recurrence. The conclusion were: 1. ringing and repairing of the venous valve were suitable for level I-II venous valvular incompetence. 2. formation of substitute valve outside the popliteal vein was suitable for level III-IV venous valvular incompetence or congenital valvular defect. 3. the width of the ringing material should be increased to 2 cm according to the pathological basis. 4. both femoral veins should be ringed in the treatment of primary valvular incompetence of double deep vein deformity. 5. the formation of substitute valve outside the popliteal vein was also available in the treatment of popliteal vein with many branches.

Adult↗