An experience with the Ross operation utilizing cryopreserved pulmonary homografts procured by and stored in our homograft valve bank

Eight patients, 4 males and 4 females ranging in age from 10 to 54 years (mean 27 +/- 13 years) underwent the Ross operation using a cryopreserved pulmonary homograft harvested by and cryopreserved in our institutional "Tissue Bank". Seven patients had a congenital bicuspid aortic valve and 3 patients had had healed infective endocarditis of the aortic valve. Four young female patients wanted to have a baby after operation. The Ross procedure was carried out utilizing aortic root replacement techniques in all patients. All patients survived and are currently in NYHA class 1, but 2 cardiac events occurred in 2 patients during the mean follow-up term of 29 +/- 19 months. The one was the anastomic stenosis between the homograft and distal pulmonary artery treated by balloon dilatation and the other was ventricular tachycardia eventually managed by the insertion of an ICD. Pulmonary autograft valve regurgitation is present in 3 patients, but it is not progressive up to the present time. Pulmonary homograft valves function well in all patients. The Ross operation for adolescents and young adults should become more popular along with more easy availability of homograft valves based upon the establishment of the "Homograft Valve Bank" system in Japan.     

Medium-term results of aortic valve replacement with cryopreserved homograft valves: importance of a domestic homograft valve bank

There are advantages to using aortic homografts as aortic valve replacements (AVR), particularly in patients with complex infective endocarditis. To determine the importance of a domestic homograft valve bank, our 23 surgical cases of homograft-AVR were reviewed. Since 2000, the Tissue Bank of the National Cardiovascular Center has supplied 23 aortic homograft valves for the treatment of complex aortic valve endocarditis. Fourteen of 23 patients had prosthetic valve endocarditis and 20 patients had an aortic annular abscess. The early mortality rate was 17% (4 patients), in all of whom prosthetic valve replacement had been performed previously. No recurrent endocarditis and no recurrent aortic regurgitation were noted at medium-term follow-up. An aortic homograft valve is the conduit of choice in cases of infective endocarditis and the importance of a domestic homograft valve bank should be recognized.     

Results of homograft aortic valve replacement for active endocarditis

Since July 1985, cryopreserved homograft prostheses have been used for aortic valve replacement in 10 patients, aged 2 to 77 years, with active endocarditis. Five patients had positive bacterial cultures from excised valves, and all had clinical findings of uncontrolled infection while receiving appropriate antibiotics. Homograft valves (four) or valved conduits (six) were implanted for treatment of sepsis (6 patients), congestive heart failure (3) or recurrent emboli (1 patient), and complicating native (5 patients) or prosthetic valve (5) endocarditis. Staphylococci (6 patients), streptococci (3), and Candida (1) were infecting organisms. Preoperatively, Doppler echocardiography showed aortic regurgitation in all patients. At operation, 9 patients had gross vegetations, 9 had single or multiple abscess cavities, and 5 had pericarditis. Complex reconstruction of the aortic valve and annulus with homograft conduits was necessary in 6 patients (3 with previous aortoventriculoplasty). Two early deaths (ventricular failure, perioperative stroke) occurred. Mean follow-up of all operative survivors was 2.1 years (range, 0.6 to 3.6 years), and one late death resulted from arrhythmia. Homograft valve regurgitation increased in 1 patient, and 7 late survivors are asymptomatic. No patient has had recurrence of endocarditis. We conclude that cryopreserved homograft aortic valve/root replacement is an effective method for management of active endocarditis complicated by annular destruction.     

The failure modes of biological prosthetic heart valves

Bioprosthetic heart valves have been used since the 1960s, starting with the use of homograft aortic valves obtained from human cadavers. Today prosthetic heart valves are used widely, and bioprostheses account for close to 40% of all heart-valve replacements. Although most bioprosthesis are still stented porcine aortic valves, the introduction of stentless valves and the increasing use of cryopreserved homograft valves has led to an upsurge of interest in bioprosthesis. There have been significant changes in the handling and fixation of porcine aortic valves; however, their modes of failure remain virtually unchanged, although many bioprosthetic valves now last for considerably longer periods. This article reviews the modes of failure of bioprosthetic heart valves.     

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.     

Cryopreserved aortic homograft replacement in 3 patients with noninfectious inflammatory vascular disease

OBJECTIVE: Although mechanical prosthetic heart valves are most commonly used for aortic valve replacement in patients with aortic regurgitation due to noninfectious inflammatory vascular disease, postoperative perivalvular leakage and/or detachment of the prosthetic valve occurs due to the fragility of the aortic annulus. Aortic root replacement with cryopreserved homografts is reported to be useful in such patients. METHODS: Three patients having aortic regurgitation associated with severe long standing noninfectious inflammatory vascular disease-2 patients with Takayasu's arteritis and 1 patient with Beh?et disease--had the aortic root replacement by a cryopreserved aortic homograft valve and conduit. RESULTS: All surgery was successful and the postoperative course uneventful. Echocardiography showed neither aortic regurgitation nor graft detachment at 6-39 months after operation. CONCLUSIONS: Homograft valve and conduit replacement is appropriate in patients with aortic regurgitation associated with noninfectious inflammatory vascular disease, with mid-term results favorable.     

Mitral Valve Replacement with Dura Mater Bioprostheses

Dura mater bioprostheses for cardiac valve replacement were first introduced in Brazil. They have been used since 1975 at the National Heart Hospital, London, as a mitral valve replacement instead of fascia lata valves or inverted aortic homograft valves. During this period 120 patients have had dura mater valves inserted in the mitral position; 29 also received an aortic valve replacement, 6 with dura mater, 20 with an aortic homograft, 2 with an aortic xeno-graft and 1 with a prosthetic valve. Perivalvular leaks occurred with seven of these mitral valves, and another seven presented with detached cusps. All but one of these 14 valves were replaced. Emboli have occurred in four of the patients, one of whom died after 35 months with thrombus on the aortic valve, but with an unaffected mitral valve. There were 15 early deaths, a hospital mortality of 12.5%. and 10 late deaths, a postoperative mortality of 9.5%. Actuarial analysis has shown a four-year postoperative survival of 78.970.     

Aortic valve replacement with fresh or cryopreserved aortic allograft--initial experience in Japan]

Aortic allograft valves were harvested from non-infected (bacterial or viral) cadavers within 24 hours of death with a family consent, and were sterilized by 4 degrees C antibiotic solution for 48 hours. Then, the allograft was preserved in the 4 degrees C nutrient medium (fresh; TC-199, calf serum and HEPES buffer) or in liquid nitrogen (-196 degrees C) after freezing to -80 degrees C by a programmed freezer. 10% dimethylsulfoxide (DMSO) was used for cryopreservation. Following germ-free confirmation, aortic allograft valves were implanted in 5 patients having aortic regurgitation with good results. Three fresh and two cryopreserved allograft valves were used. Although the follow-up term is very short (maximum 1 year) at the present time, the valve function is quite satisfactory, confirmed by cardiac catheterization and echocardiography. This is the first report in Japan with regard to cryopreservation of allograft valves and clinical use of fresh or cryopreserved valves. We believe that realization and progress of allograft preservation by cryo-technique and establishment of the tissue bank are important for the development of cardiovascular surgery in Japan.     

Belgian and European Experience with the European Homograft Bank (EHB) Cryopreserved Allograft Valves.-Assessment of a 20 Year Activity

European Homograft Bank (EHB) has been selecting, preparing, storing and distributing the cryopreserved allograft valves in Belgium and some other European Countries since 1989. It was established in 1988 by a pathologist and the cardiac and vascular surgeons from Belgian and other European centres as an inter-university, international nonprofit association. Due to its neutral behavior and very high quality criteria, European Homograft Bank became one of the prominent heart valve banks in Europe and wider. It collaborates with the transplant coordination in donor selection as well as with the huge network of the implanting surgeons in Belgium and other European Countries. The EHB responsible discusses with the implanting surgeon the allograft selection on basis of the indication and the patients state of emergency.

A total of 8.911 donor heart valves have been evaluated in EHB during the last 20 years. After selection, 5.258 allograft valves (1.996 aortic, 3.189 pulmonary and 73 mitral) were cryopreserved and stored in vapors of liquid nitrogen between 6 weeks and 5 years. A total of 4.516 allograft valves (1.391 aortic, 2.620 pulmonary and 48 mitral) were implanted in the left or right ventricular outflow tract for replacement of the diseased aortic or pulmonary valve and for mitral or tricuspid valve replacement or repair. In 1.380 cases the allograft valves were used for right ventricular outflow tract reconstruction as part of the Ross-procedure, whereas in 668 cases the allograft valve served for replacement of the aortic valve for endocarditis. The most important indications for use of cryopreserved allograft valves were: important cardiac and valve malformation in children, female patients of child-bearing age with diseased cardiac valves, cases with contra-indication for anti-coagulation and the patients with severe endocarditis with septal or annular abscesses. Although the number of the donation increased by year, the available allograft valves in stock are still insufficient to respond to all the surgeons’ request for different indications.     

Structural degeneration of pulmonary homografts used as aortic valve substitute underlines early graft failure.

OBJECTIVES: The limited availability of donor valves and experimental evidence that pulmonary valves can withstand systemic pressure made us use cryopreserved pulmonary homografts as aortic valve substitutes. We observed a high incidence of early reoperation because of severe graft insufficiency due to cuspal tears. The mid-term results are evaluated in this study and histological analysis of explanted homografts is performed to investigate the cause of graft failure. METHODS: From December 1991 to April 1994, 16 patients (13 male; mean age 37.3 years, range 21-59 years) underwent aortic valve replacement with a cryopreserved pulmonary homograft. The indication was endocarditis (n = 4), bioprosthesis degeneration (n = 3) or congenital aortic valve disease (n = 9). All homografts were implanted freehand in the subcoronary position. All patients were contacted for follow-up and recent echo-Doppler studies were reviewed. Six explanted homografts were examined microscopically using routine histological techniques to analyze changes in cell population, collagen and elastic fiber structure. RESULTS: Follow-up was complete in all patients. Reoperation was required in ten patients because of severe graft incompetence (mean implantation time 5.9 years, range 2.8-8.0 years). In two patients, recurrent endocarditis was the cause of graft failure. In the other eight patients the leaflets looked pliable and thin with gross tearing in one or more cusps. The histopathologic changes observed were remarkably similar in all examined grafts: the cusp tissue was almost non-cellular and the collagen fiber structure had mostly disappeared. At the site of rupture, the tissue had become thin with strongly degenerated collagen and elastic fiber structure. In the six patients with a homograft remaining in situ, echo-Doppler showed trivial to mild insufficiency in five cases and moderate to severe in one case, whereas no significant gradients were observed. CONCLUSIONS: We concluded that structural reduction of cell number and degenerative alterations in the molecular composition of the extracellular matrix in valve tissue is the main cause of early graft failure in this series. The use of cryopreserved pulmonary homografts in the systemic circulation is therefore not advised.     

Short-term result of aortic valve replacement with cryopreserved homograft valve in the University of Tokyo Tissue Bank

The short-term results after aortic root replacement with 11 cryopreserved aortic homografts was examined. Since 1998, the University of Tokyo Tissue Bank has supplied 11 aortic homograft valves. Nine of the recipients were male, and the average age was 51.2 years. Nine out of 11 patients had suffered from a serious condition of native or prosthetic valve infectious endocarditis. All of the patients underwent aortic root replacement, and the blood type between the patient and the homograft was matched in 8 of the patients. Only 1 patient died (9.1%) in the short-term due to sepsis. The preoperative degree of aortic valve regurgitation in all of the cases was third or fourth while the regurgitation disappeared after the operation in all of them. Thinking of the serious condition of our cases preoperatively, the 9.1% operative mortality was quite acceptable. Long-term follow-up is necessary to estimate the quality of the homografts.     

Recycled heart valves from transplant patients

Forty heart transplantations were performed at the Toronto Western Hospital, University of Toronto, from October 1987 to December 1989. Each heart extracted from a recipient was examined with the view of using the aortic valve as a homograft for another patient requiring aortic valve replacement. Of the 40 explanted hearts, 26 had normal aortic valves that were potentially suitable for homografting, and 14 had aortic valves judged as unsuitable. Of the potentially suitable valves, four were preserved for ex vivo arrhythmia studies requiring aortic root perfusion and four were damaged during harvesting. The remaining 18 usable valves were sized at the time of explantation and stored in an antibiotic solution at 4 degrees C. Thirteen valves were transplanted within 10 days of harvesting, and five were discarded because no suitable recipients were available within this period. There were no operative deaths or valve-related complications in the 13 homograft valve recipients. Mean follow-up was 13 months (range, 3 to 27 months). One patient required replacement of the homograft with a mechanical prosthesis because of insufficiency and stenosis. All patients are alive, are New York Heart Association functional class status I, and have insignificant valve gradients based on Doppler echocardiography. Although hearts removed from transplant recipients are severely diseased, the aortic valves are frequently normal and should be considered for use as homografts for other patients requiring aortic valve replacement.     

Establishment of a bank of cryopreserved valve homografts and clinical use in ninety-two patients]

Good long-term results obtained with homologous valve grafts, specially for correction of congenital cardiac defects, prompted us to create a local cryopreserved homograft bank. A 5-year experience is described, including indications for harvesting, techniques of preparation, cryopreservation and thawing. During this period, 195 homografts entered the bank and 92 were used. Among these 92 clinical cases, 74 consisted of right ventricular outflow tract reconstruction (47 valved conduit and 27 monocusp bearing patch) and 17 were left ventricular outflow tract reconstructions (11 free hand aortic valve and 6 aortic root replacement). Only one case was a tricuspid replacement with a stented homograft. Short-term results, with these homografts, are satisfactory and are compared with long-term results reported in the literature. The authors insist on using very thorough techniques and constant quality control. New developments should include viability control and immunological studies.     

Long-Term Performance of Homograft and Autograft Valves

Five hundred and eighty homograft valves have been inserted into the aortic position as isolated valve replacements, and followed up for 7–14 years. After ten years 90% of frozen homografts, 80% of autografts and 70% of freeze-dried homografts were free of valve-related death. There was only one embolism reported giving an incidence of one embolism per 143,928 patient months. Degeneration occurred in 14% of the autografts, in 30% of the freeze dried and in 60% of the frozen homografts after ten years. Eighty per cent of the fresh homografts have been free of degeneration after seven years, and 54% of freeze-dried valves have been free of degeneration after 14 years. Long-term performance of homograft and autograft valves in the aortic positon is comparable to that of any prosthetic or bioprosthetic valve. In addition, they are non-thrombogenic and excellent in terms of patient survival.     

Clinical experience with heart valve homografts in Brazil

The purpose of this paper is to describe the development and progress of the first heart valve homograft bank in Brazil as well as to report the 5-year clinical results. The bank was started in 1995 and employs modern techniques of cryopreservation. Organ procurement increased from 11 hearts in 1995 to 138 hearts in 2000. In the beginning of the experience, only 2 hospitals were using these valves, but this increased to 18 centers in 2000. Clinical experience at the major center includes 117 cases of the Ross procedure, 62 aortic homograft implantations, and 18 cases of mitral homografts. Five-year survival after the Ross procedure was 99.1%, and survival free from any kind of complication was 88.8%. No patients are on anticoagulants, and the incidence of thromboembolism was null. We conclude that auto- and homografts are probably the best alternative to aortic valve replacement for young patients in developing countries.     

无支架二尖瓣制备、保存和体外三尖瓣置换技术探讨

目的观察深低温保存猪二尖瓣超微结构,探索无支架二尖瓣制作方法和置换三尖瓣技术。方法采用猪二尖瓣制成无支架瓣膜,抗生素灭菌深低温保存,透射电子显微镜观察深低温保存１个月的猪二尖瓣组织结构。将离体猪心三尖瓣切除,将无支架猪二尖瓣前瓣环缝合于隔瓣环,二尖瓣后瓣环缝合于三尖瓣前后瓣环,两乳头肌缝合于右心室前壁,完成无支架二尖瓣置换三尖瓣,注水试验观察瓣膜启闭功能。结果透射电子显微镜观察到,深低温保存猪二尖瓣内皮细胞结构完整,胶原纤维结构致密,排列整齐,成纤维细胞胞膜完整,细胞核无固缩现象,线粒体无明显肿胀。无支架二尖瓣置换的离体猪心三尖瓣启闭功能良好。结论深低温保存的无支架猪二尖瓣结构完整,活性得到很好保持。瓣膜设计合理,用此瓣膜置换三尖瓣技术可行     

Left ventricular mass reduction after aortic valve replacement: homografts, stentless and stented valves.

BACKGROUND: We studied the effect of four different types of prosthetic aortic valves on time course and extent of regression of left ventricular hypertrophy after aortic valve replacement for aortic stenosis. METHODS: Four groups of 10 patients each were randomly assigned to receive: (1) aortic homograft preserved in antibiotic solution at 4 degrees C, (2) Toronto stentless porcine valve, (3) Medtronic Freestyle stentless valve, or (4) Medtronic Intact aortic valve. The left ventricular mass index, effective orifice area index, and peak and mean transaortic gradients were measured by Doppler echocardiography before the operation and 8 months postoperatively. RESULTS: The hemodynamic performance indices were much better for the homograft and stentless valves than for the stented one. The absolute left ventricular mass index reduction was greater in the homograft group compared with the Intact (p = 0.0004) and Toronto (p = 0.007) groups. The extent of percent left ventricular mass index reduction was greater only in the homograft group versus Intact group (p = 0.005). The multilinear regression analysis showed that the only predictors of a larger percentage of left ventricular mass index reduction were the homograft type, a higher valve size index, and a higher preoperative left ventricular mass index. CONCLUSIONS: When a stentless or homograft aortic valve was used instead of a stented valve to replace a stenotic aortic valve there was more complete or at least faster regression of left ventricular hypertrophy. The hemodynamic performance of stentless porcine valves was similar to that of aortic homografts, nevertheless the aortic homografts preserved in antibiotic solution offered a faster regression of left ventricular hypertrophy during the same period of time.     

Prosthetic valve endocarditis: complication following cardiac surgery

Prosthetic valve endocarditis (PVE) is a rare but serious complication following valve replacement surgery. Early-phase PVE, which occurs within 60 days of valve replacement, may be associated with nosocomial or intraoperative infection. The primary organism of this type is the Staphylococcus group. Late-phase PVE, which usually occurs more than one year after valve replacement, may be caused by a mechanism similar to that of native valve endocarditis. The primary causative organism of this type would thus be similar to that of native valve endocarditis, which is the Streptococcus group. To treat PVE effectively, it is extremely important to identify the primary causative organism. If uncontrollable cardiac failure or infection occurs, a second valve replacement is absolutely indicated. A cryopreserved aortic valve allograft, if available, is the first choice for PVE. Features such as cell viability, less compliance mismatch, and postantibiotic process could be reasons for the anti-infective characteristics of cryopreserved allografts. Currently, allograft valves are not widely available in Japan; therefore, conventional prosthetic valves are usually used. The use of antibiotic-soaked prosthetic valves or stentless xenograft valves has also been attempted. A genetic or tissue engineering approach could open a new era to overcome this lethal complication.     

Ten Years' Experience with Pulmonary Autograft Replacements for Aortic Valve Disease

Pulmonary autograft valves have been used to replace isolated, diseased aortic valves for 10 years, with a long-term survival of 73%. The low incidence of degeneration supports the principle that the autograft valve is a potentially permanent valve replacement. Operative mortality is now less than 5%, despite the longer, more complex operation. The current use of fresh homograft valves for the pulmonary replacement has contributed to these excellent long-term results.     

液氮保存同种带支架人工瓣膜流体力学测试

目的：利用脉动流模拟实验装置测试液氮保存同种带支架瓣膜流体力学性能，同时与国产perfect牛心包人工瓣膜对比研究。方法：采集同种瓣膜，缝制成21^#、23^#、25^#同种带支架主动脉和同种带支架肺动脉人工瓣膜，经液氮保存，使用国产脉动流实验装置测试瓣膜流体力学性能，采用ISO／FDA浮估标准，分别测量各流量下的跨瓣压差、有效瓣口面积(EOA)和回流比。并与相应型号国产perfect牛心包人工瓣膜对比研究。结果：21^#、23^#、25^#同种带支架主动脉和肺动脉瓣膜的跨瓣压差和回流百分比差异无显著性，但较perfect瓣大。同种带支架主、肺动脉瓣膜的EOA差异无显著性，但较perfect牛心包生物瓣膜的略小些。同种带支架瓣膜实际开口面积(AOA)小于perfect牛心包瓣，但有效瓣口面积，实际开口面积比值无差别。结论：同种带支架主动脉和肺动脉人工瓣膜流体力学性能满意，同种带支架主动脉瓣膜与同种带支架肺动脉瓣膜流体力学性能无差别。