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).     

Classification of congenitally bicuspid aortic valve and its angiographic and surgical significance]

From January, 1978 to December, 1990, 85 patients with congenital bicuspid aortic valve underwent aortic valve replacements (AVR) with St. Jude Medical valve prosthesis. We classified congenital bicuspid aortic valve into four types. Type I (44.7%): Two cusps are situated right and left, a coronary artery arises from each related sinus of valsalva. Type II (22.4%): Type I + raphe in the right cusp. Type III (3.5%): one cusp is located anteriorly, the other posteriorly and both coronary arteries arise from anterior cusp. Type IV (29.4%): Type III + raphe in the anterior cusp. Regarding to preoperative diagnosis, aortic stenosis dominated in Type I (78.8%) and aortic regurgitation dominated in Type IV (72.0%). Implanted valve sizes were 22.2 +/- 1.8 (Type I), 23.4 +/- 1.6 (Type II) and 24.0 +/- 2.2 (Type IV). There was a significant difference between Type I and Type II, same as Type I and Type IV. Babb's method and outflow measurement method were utilized to predict the aortic annular size. However, both of them were not reliable for estimating the size of the aortic annulus in cases of aortic stenosis undergoing AVR with a 21 mm prosthesis.     

In vitro observations of greater saphenous vein valves during pulsatile and nonpulsatile flow and following lysis

A significant number of saphenous vein femoral-popliteal bypass graft failures have been attributed to flow abnormalities caused by venous valves. Seventy-seven greater saphenous vein valves were observed and photographed through a 0-degree choledochoscope during pulsatile and nonpulsatile flow. No valve was seen to lie flat against the vein wall. With pulsatile flow the valves were noted to close during diastole. Stasis was noted within the valve cusps. Twenty-three valves produced photographs of sufficient quality to allow measurement of the luminal obstruction caused by the valves. This valvular obstruction represented 61% ± 12% of the total vein lumen. Fifty venous valves were lysed by five different techniques: the microscissors, the Connolly vein stripper, the Mills valvulotome, the venotomy valvulectomy of Hall, and eversion valvulectomy. The first three methods created valvular incompetence, but flaps of valve cusps were observed to disturb flow and place potentially thrombogenic surfaces within the vein lumen. Valvulectomy, whether by venotomy or eversion, removed the valve cusps satisfactorily. (J VASC SURG 1984;1:356-61.)     

Influence of blood contact on the calcification of glutaraldehyde-pretreated porcine aortic valves.

BACKGROUND: The rat subcutaneous model reproduces clinically observed mineralization of bioprosthetic tissues. However, the effectiveness of antimineralization treatment can be overestimated in subcutaneous implants, since specimens using this model are not subjected to mechanical and dynamic stress or blood-surface contact. The purpose of this study was to evaluate the influence of blood contact on the calcification of bioprosthetic valves. METHODS: Glutaraldehyde-pretreated porcine aortic valves were prepared. Aortic wall and cusp discs were implanted subcutaneously in six rats for 8 weeks and were implanted within the jugular vein wall in six sheep for 3 and 6 months (blood contact model). Tissue discs were analyzed by gross inspection, radiography and light microscopy. Calcium content was determined by atomic absorption spectrometry. RESULTS: X-ray and light microscopic examination showed calcification in the cusps to be higher than that in the aortic wall in the rat subcutaneous model. On the other hand, in the blood contact model, the cusps were slightly calcified and calcification in the aortic wall was more pronounced. Calcium analysis in rats revealed more calcium in the cusp than in the aortic wall (71.5+/-9.7 g/mg dry tissue vs. 53.7+/-2.6, p=0.09). Tests for calcium content of the jugular vein samples in sheep showed significantly more calcium in the aortic wall than in the cusp (3 months, 7.9+/-1.5 vs. 0.3+/-0.1, p<0.0001; 6 months, 77.2+/-6.1 vs. 27.2+/-10.2, p=0.0002). In addition, aortic wall and cusp calcification significantly increased with time. CONCLUSIONS: These data suggest that the results from the rat subcutaneous model were completely opposite to those for the blood contact model. This study confirms the need to include blood contact as a factor in in vivo pre-clinical valve testing.     

A case of quadricuspid aortic valve with aortic regurgitation

A 67-year-old man with grade 3 aortic valve regurgitation was found to have a quadricuspid aortic valve. The aortic valve consisted of 1 large, 2 intermediate and 1 small sized cusp. An accessory cusp located between the right and noncoronary cusps, and shaped like a hammock which sling by the fibrous strings originating from the both commissures to the aortic wall. Aortic valve replacement was successfully performed with a 23 mm St. Jude Medical prosthetic valve, and the patient is asymptomatic five months post-operatively. Histological examination of the resected cusps showed fibrous thickening and no rheumatic valvulitis or infective endocarditis.     

Quadricuspid aortic valve: case reports

Two cases of quadricuspid aortic valve with aortic regurgitation are reported. Case 1, a 66-year-old woman was operated on because of aortic regurgitation, and an aortic valve replacement with a bioprosthesis was performed. When the valve was exposed during the operation, it showed four cusps, three of which were of equal size and one smaller cusp which was interposed between the right and left coronary cusp. Case 2, a 46-year-old man was diagnosed, using echocardiography and aortography before surgery, as suffering from aortic regurgitation because of a quadricuspid aortic valve. During surgery, two larger cusps and two smaller cusps and a displacement of the right coronary artery ostium, (which was placed in a lower position and close to the commissure between the right coronary and the right posterior cusps) were found. The four cusps were excised and replaced by a tilting disc prosthesis. In both cases, the postoperative recovery was uneventful. Using the 24 cases from the literature and two of our own cases, the correlation between the size or the position of the accessory cusp and the occurrence of aortic regurgitation was analyzed. The larger the accessory cusp was, the higher the incidence of aortic regurgitation occurred (p less than 0.05).     

A study of the mechanical properties of fresh and preserved human femoral vein wall and valve cusps

In the hope that some varieties of the post-phlebitic syndrome might be treated by implanting a preserved vein valve, studies have been made of the mechanical properties of vein valves and vein wall before and after preservation with glutaraldehyde. The ultimate tensile strength (breaking stress) and strain (extensibility) of strips of vein wall and valve leaflet were measured with a Nene tensiometer. The ultimate tensile strength of valve leaflet was found to be twice that of vein wall. Preservation in glutaraldehyde (0.2 per cent, pH 7.4, for 7 days) with valve cusps closed by a minimum head of pressure caused no change in breaking stress or extensibility.     

Influence of prosthetic design on durability of the Liotta porcine valve in the mitral position

From March 1979 to December 1984, the Liotta low-profile porcine bioprosthesis was employed for mitral valve replacement in 71 patients to avoid potential left ventricle-prosthesis mismatch occasionally observed with the standard, high-profile, Hancock porcine xenograft. Follow-up of 61 operative survivors showed at 10 years an actuarial survival of 67% +/- 7%, freedom from thromboemboli of 96% +/- 2%, freedom from structural deterioration of 63% +/- 11% and freedom from all Liotta bioprosthesis-related complications of 53% +/- 10%. Complications related to excessive protrusion of the stent into the left ventricular cavity were eliminated with the Liotta bioprosthesis; the peculiar stent configuration, however, was responsible for an increased rate of structural deterioration requiring reoperation in 10 patients (2.8% +/- 0.9%/patient-year) at a mean interval of 76 +/- 18 months after mitral valve replacement (range, 45 to 106 months). Common findings in all explants were cusp prolapse, cusp tears, and commissural rupture related to various degrees of tissue calcification, constantly leading to severe prosthetic incompetence. As also shown experimentally, such structural changes have been attributed to increased systolic stresses on the closed cusps, favored by excessive reduction of the stent height. Our experience shows that the Liotta bioprosthesis used for mitral valve replacement does not provide any clear-cut advantage over standard porcine bioprostheses and that its long-term durability appears affected by the unique prosthetic design.     

Calcification resistance with aluminum-ethanol treated porcine aortic valve bioprostheses in juvenile sheep

BACKGROUND: Calcification of glutaraldehyde fixed bioprosthetic heart valve replacements frequently leads to the clinical failure of these devices. Previous research by our group has demonstrated that ethanol pretreatment prevents bioprosthetic cusp calcification, but not aortic wall calcification. We have also shown that aluminum chloride pretreatment prevents bioprosthetic aortic wall calcification. This study evaluated the combined use of aluminum and ethanol to prevent both bioprosthetic porcine aortic valve cusp and aortic wall calcification in rat subcutaneous implants, and the juvenile sheep mitral valve replacement model. METHODS: Glutaraldehyde fixed cusps and aortic wall samples were pretreated sequentially first with aluminum chloride (AlCl3) followed by ethanol pretreatment. These samples were then implanted subdermally in rats with explants at 21 and 63 days. Stent mounted bioprostheses were prepared either sequentially as previously described or differentially with AlCl3 exposure restricted to the aortic wall followed by ethanol pretreatment. Mitral valve replacements were carried out in juvenile sheep with elective retrievals at 90 days. RESULTS: Rat subdermal explants demonstrated that sequential exposure to AlCl3 and ethanol completely inhibited bioprosthetic cusp and aortic wall calcification compared with controls. However the sheep results were markedly different. The differential sheep explant group exhibited very low levels of cusp and wall calcium. The glutaraldehyde group exhibited little cusp calcification, but prominent aortic wall calcification. All sheep in the two groups previously described lived to term without evidence of valvular dysfunction. In contrast, animals in the sequential group exhibited increased levels of cusp calcification. None of the animals in this group survived to term. Pathologic analysis of the valves in the sequential group determined that valve failure was caused by calcification and stenosis of the aortic cusps. CONCLUSIONS: The results clearly demonstrate that a combination of aluminum and ethanol reduced aortic wall calcification and prevented cuspal calcification. Furthermore, this study demonstrates that exclusion of aluminum from the cusp eliminated the cuspal calcification seen when aluminum and ethanol treatments were administered in a sequential manner.     

Repair of trileaflet aortic valve prolapse: mid-term outcome in patients with normal aortic root morphology

We described our mid-term results in repairing prolapsing aortic cusps in 21 patients with aortic regurgitation and normal aortic root morphology. Aortic regurgitation was moderate-severe in five patients and severe in 16 patients. Prolapse involved the left cusp in four patients (19%), the right cusp in 10 patients (47%) and the non-coronary cusp in 7 (33%) patients. Correction of the prolapsing cusp was achieved by either free edge plication, triangular resection or resuspension with polytetrafluoroethylene sutures, frequently associated to a subcommissural annuloplasty. There was no hospital death. At discharge transthoracic echocardiography, 18 patients (85%) showed no residual aortic regurgitation and three patients (14%) had trivial aortic regurgitation with a central jet. Mean clinical follow-up was 27.2+/-17.1 months (range: 10-72 months). Overall survival was 90.5%. At follow-up transthoracic echocardiography, fourteen patients (73%) were free from aortic regurgitation and five patients (26%) had mild aortic regurgitation without clinical signs of congestive heart failure. Correction of valve prolapse appears a reasonable extension of the original techniques of valve-preserving surgery.     

Midterm results of aortic valve repair with the pericardial cusp extension technique in rheumatic valve disease

BACKGROUND: The encouraging results of valve repair in the atrioventricular valves have influenced a decision about aortic valve (AV) reconstruction. We report our experience with pericardial cusp extension to repair rheumatic AV disease. METHODS: From 1993 to 1998, 46 patients (25 women, 21 men) with a mean age of 31.5 +/- 12.2 years (range, 15 to 58 years) underwent AV repair. Twenty-two (47.8%) patients had moderate and 24 (52.2%) had severe aortic insufficiency (AI). Severe cusp retraction was repaired with glutaraldehyde-treated autologous pericardium. Twenty-one patients had more than one maneuver (mean, 1.8) to attain competence besides augmentation, which consisted of the release of stenotic commissures (in 11 cases), thinning of the AV cusps (in 10 cases), and resuspension of the cusps (in 17 cases). Simultaneous mitral valve repair was performed on 17 patients. Eight patients received triple valve reconstruction. RESULTS: There was no early mortality. Thirty patients no longer had AI with any significant transvalvular gradients. Five patients were followed with mild residual AI, and 2 patients with moderate AI not requiring reoperation. Nine patients developing severe AI required AV replacement with a reoperation rate 19.6% (4.26%/patient-year). The mean interval between repair and reoperation was 28.2 +/- 18.3 months (range, 3 to 58 months). The mean observation time was 4.6 +/- 3 years (211.6 patient-years). Late mortality rate was 2.2% with 1 patient. The significant negative predictors of aortic reoperation determined by univariate analysis were preoperative New York Heart Association class (p = 0.002) and postoperative severe AI (p < 0.001). Cox hazard studies identified that all risk factors were insignificant for aortic reoperation. The actuarial rate of freedom from aortic reoperation was 76.1% +/- 7% at 7.5 years. CONCLUSIONS: Although AV repair by extension with pericardium is worth considering with an acceptable solution to achieve a good geometry from unequal cusps, especially in young rheumatic patients for preservation of the native AV, the patients should be followed periodically for reoperation risk.     

Total correction of truncus arteriosus with severe truncal valve insufficiency in neonate]

The prognosis of infants with truncus arteriosus associated with severe truncal valve insufficiency is quite poor. Total correction was successfully performed in a neonate with such a complicated anomaly. The patient was 21 days old female with anuria due to severe congestive heart failure preoperatively in spite of medical treatment. She underwent Rastelli operation and pulmonary artery was reconstructed using autologous pericardial 3 valved conduit. Truncal valve was 4 cusps with the malformed nodular margins and one cusp had cleft. This cleft was closed suturing the cleft cusp and adjacent cusp each other and annuloplasty was added in 4 commissures. She survived and her truncal valve insufficiency was still mild at 2 years post-operative period. Although total correction with truncal valve repair for such a severely ill neonate and young infant with truncus arteriosus as this patient has not been reported, our experience suggests that severe truncal valve insufficiency could be fairly well repaired by valvulo-annuloplasty.     

Aortic valve cusp vessel density: relationship with tissue thickness

OBJECTIVES: The presence of a microvasculature within aortic cusps implies that tissue oxygen requirements exceed the amount deliverable by diffusion from the tissue surfaces alone. For the design of a successful tissue-engineered valve replacement, the effect of diffusion distance (tissue thickness) on oxygen delivery must be considered. We therefore examined in normal aortic valve cusps the relationship between the presence of microvessels and the tissue thickness. METHODS: Thirty porcine aortic valve cusps were excised and examined after cusp microvessels were pressure filled with a carbon particle solution. Cusp images were captured for stereographic vessel density analysis, and cusp thickness was determined with a radiographic technique. Histologic cross-sections were evaluated to determine vessel depth from the cusp surface. RESULTS: Cusp basal regions measured 0.69 to 0.86 mm in thickness, significantly thicker (P =.001) than the rest of the cusp, which measured 0.36 to 0.48 mm. In general a vascular bed was present when cusp thickness exceeded 0.5 mm, with a median value of 5.16 vessels/mm(3). CONCLUSIONS: From published values of arterial wall oxygen consumption and diffusivity, we predicted that the probable maximum oxygen diffusion distance for valve tissue would be about 0.2 mm. This was consistent with our physical findings, which implies that central tissue anoxia is avoided by the capillary bed. An avascular tissue-engineered valve metabolically similar to an aortic valve should therefore not exceed a thickness of approximately 0.40 mm.     

Percutaneous autologous venous valve transplantation: short-term feasibility study in an ovine model

BACKGROUND: Limited experience with bioprosthetic venous valve percutaneously inserted into femoral veins in 15 patients has been promising in short-term results only to show disappointing long-term results. Percutaneous autogenous venous valve (PAVV) transplantation was explored in an ovine model as a possible alternative treatment. METHODS: PAVV consisted of a vein segment containing a valve that was attached to a stent template. The stent templates (n = 9) were designed and hand made in our research laboratory. They consist of two stainless steel square stents 13 or 15 mm in diameter to fit the ovine jugular veins (JV), which ranges from 10 to 15 mm in diameter. A valve-containing segment of JV was harvested and attached with sutures and barbs inside the stent template (n = 9). The valve devices were then manually folded and front loaded inside the 4 cm chamber of the 13F delivery sheath and delivered into the contralateral JV by femoral vein approach. Transplanted PAVVs were studied by immediate and 3 months venograms. Animals were euthanized at 3 months, and jugular veins harvested to perform angioscopic evaluations in vitro. RESULTS: PAVV transplantation was successful in all nine animals. Good valve function with no reflux was observed on immediate and 3 months venograms in eight valves. The transplanted maximal JV diameter ranged from 10.2 mm to 15.4 mm (mean 13.1 +/- 1.5 mm). Venoscopic examination revealed intact, flexible, nonthickened valve leaflets in eight specimens. One PAVV exhibited normal function of one leaflet only; the other cusp was accidentally cut during the transplantation procedure. All transplanted autologous valves were free of thrombus and incorporated into the vein wall of the host vessel. CONCLUSION: This study demonstrated that autogenous valve transplants remained patent and competent without long-term anticoagulation for up to 3 months. The percutaneous autogenous venous valve may provide in future minimally invasive treatment for patients with chronic deep venous insufficiency, but long-term studies need to be done to document its continued patency and function.     

Aortic valve repair using bovine pericardium for cusp extension

Aortic valve repair with the use of individually tailored bovine pericardial extensions to the native cusps was performed in 20 patients (mean age 22 years) with severe rheumatic aortic valve incompetence. After aortic valve repair, the diastolic pressures increased significantly from a mean (+/- standard deviation) of 49 +/- 14 to 73 +/- 8 mm Hg (p less than 0.001), and cardiac catheterization showed a marked reduction or total correction of the angiographic degree of aortic regurgitation. All the patients were free of symptoms over a mean follow-up period of 7.5 months (1 to 23 months); the first 11 patients have had a mean follow-up period of 12 months. Attention is called to this short period of follow-up. Aortic valve repair with the use of bovine pericardium for cusp extension may prove to be an effective method of treatment for rheumatic aortic valve incompetence.     

An experimental study of the use of fresh aortic valve homograft for the usage of the vena caval valve. Part 1. The evaluation of hemodynamics and cineangiographic study

The purpose of this study is to develop a vena caval valve using the fresh aortic valve homograft. A preliminary study was performed in six dogs by interposing a cryopreserved aortic valve homograft with sinus Valsalva into SVC. After making the tricuspid regurgitation, the aortic valve homograft was closed by the regurgitant flow in the systolic phase and opened by the venous return in the diastolic phase. The preliminary study showed that the cryopreserved aortic valve homograft with sinus Valsalva was useful as a vena caval valve immediately after the implantation. Fresh aortic valve homografts were implanted in 11 dogs in the same manner. Eighteen pressure studies and cine-angiographies were performed in six dogs on 8 to 165 days after the implantation. Pressure studies showed minimal/small pressure gradients across the implanted homografts. However, cineangiography revealed appearance of regurgitation through the implanted homograft three months later. Thromboembolism was not happened in all dogs at all. Therefore, we concluded that the fresh aortic homograft with sinus Valsalva might be clinically feasible for use as a vena caval valve.     

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.     

Aortic regurgitation caused by rupture of the abnormal fibrous band between the aortic valve and aortic wall

This report documents the sudden onset of aortic regurgitation (AR) by an exceptional cause. A 68-year-old woman suddenly experienced general fatigue, and AR was diagnosed. One year later, we performed aortic valve replacement. At surgery, three aortic cusps with a larger noncoronary cusp had prolapsed along with a free-floating fibrous band that had previously anchored the cusp to the aortic wall. Its rupture had induced the sudden onset of AR. There was no sign of infectious endocarditis. We performed successful aortic valve replacement.     

下肢深静脉瓣膜功能不全的瓣膜外修复成形术

目的研究和评价利用瓣膜外修复成形术治疗下肢深静脉瓣膜功能不全的疗效。方法对下肢深静脉瓣膜功能不全的２６例患者（３７条肢体）施以股静脉瓣膜外修复成形术。其中男１２例,女１４例;年龄１６～６９岁,平均年龄（５０８±１００）岁。所有肢体均施行股浅静脉第一对瓣膜外修复成形术,其中７条肢体加施股浅静脉第二对瓣膜外修复成形术,６条肢体加施股总静脉外瓣膜修复成形术。结果８１１％（３０／３７）的患肢静脉性跛行、酸胀、疼痛等症状消失,１８９％（７／３７）的患肢症状明显改善,所有肢体静脉曲张消失,７／９的肢体溃疡愈合。彩超复查除有４条肢体瓣膜功能不全Ⅰ～Ⅱ度外,其余肢体（８９２％）瓣膜功能恢复正常。结论深静脉外瓣膜修复成形术是治疗下肢深静脉瓣膜功能不全比较理想和有效的方法