Evaluation of long-term results of homograft and heterograft valves in extracardiac conduits

Between 1971 and 1982, 249 patients received right heart extracardiac conduits. The 173 patients who survived 30 days were reviewed retrospectively; 72 had antibiotic-sterilized aortic homografts, 97 had xenografts of various types, and four had valveless tubes. Reoperation for conduit obstruction was required as early as 13 months after the original operation, but actuarial analysis showed no differences in overall performance of homograft and heterograft conduit groups with respect to late death or survival free of conduit obstruction. More important risk factors for late death or the need for reoperation were the severity of the underlying cardiac lesions and the influence of early postoperative complications. When analyzed statistically, the performance of conduits bearing homografts was disappointing, influenced sometimes by complications in the Dacron extension tubes. Repairs dispensing with conduits entirely should be evaluated.     

兔颈动脉移植同种主动脉带瓣血管模型的建立

目的 建立兔两侧颈动脉移植同种带瓣血管模型。方法 成年新西兰兔１０只作为受体分５组。１个月龄的新西兰白兔２０只作为供体，取其主动脉带瓣血管，移植于受体的两侧颈动脉，术后７、１４、２８、６０、１２０ｄ分别取出每组受体所移植的同种瓣并观察血流通常情况及有无血栓形成。结果 受体全部存活，１０只成年兔的两侧颈动脉血流均通畅，大体标本无血栓形成。结论 此模型对动物损伤小，显露好，且双侧移植有利于分组间对比研     

去细胞组织工程同种心脏瓣膜的免疫学特征

目的构建去细胞的组织工程同种心脏瓣膜,探讨其免疫学特性变化。方法取液氮保存的人同种主动脉带瓣管道,采用低渗液-去污剂(1％去氧胆酸,1％DOA)-核酸酶[20mg／L核糖核酸酶(RNase)和200 mg／L去氧核糖核酸酶(DNase)]去细胞法去除同种心脏瓣膜、管壁组织及肌肉中所有的细胞成分,保留完整的细胞外基质,构建去细胞的组织工程同种心脏瓣膜;采用免疫组织化学方法测定HLA-DR抗原在同种心脏瓣膜组织中的表达;行大鼠皮下移植试验,评价组织学变化及Van Kosaa银染色法定性分析、原子吸收光度计法定量分析组织的钙化程度。结果去细胞同种心脏瓣膜的白细胞抗原-DR(HLA-DR)表达较深低温液氮保存同种心脏瓣膜(HVA)显著下降;大鼠皮下移植8周后,去细胞同种心脏瓣膜组织中的炎性细胞浸润显著减少,定性分析表明去细胞组瓣叶和管壁组织中呈黑色颗粒的钙盐沉积较深低温液氮组显著下降,尤管壁组织更为显著;定量分析亦表明去细胞瓣叶和管壁组织的钙化程度显著下降(瓣叶:去细胞组0．83±0．17 mg／ g,深低温液氮组[(1．39±0．26)mg／g,P<0．05];管壁:去细胞组(2．35±2．58)mg／g,深低温液氮组[(42．66±7．46)mg／g,P<0．05)]。结论去细胞同种心脏瓣膜的免疫原性显著下降,有望减轻移植后免疫反应,延长同种心脏瓣膜的使用寿命。     

Results of the Ross operation in a pediatric population

Objective: To analyse the results of the mid-term clinical and echocardiographic follow-up of the pediatric Ross operation. Methods: Echo-Doppler follow-up of 53 consecutive pediatric Ross procedures performed between 1994 and 2003. Median age was 9.7 years at time of operation (2 weeks–17.7 years). Six patients were younger than 3 months. Median age at follow-up was 15.6 years. Aortic valve/left ventricular outflow tract (LVOT) anomalies were congenital in 49 (92%). Seventy percent had previous surgery or balloon valvuloplasty. Root replacement was used in all. Thirteen patients (25%) had LVOT enlargement. Mean cross-clamp time was 113 (69–189) minutes. Results: Early mortality occurred in 3 patients after emergency surgery following balloon failure (n=1) and extended Ross following interrupted arch/VSD repair (n=2). Late mortality was due to LV fibroelastosis in 2 patients and complicated pulmonary artery stenting in another. RVOT reoperations were required because of late homograft obstruction in 2 patients and because of pulmonary artery stenosis in another. Five patients (9.4%) were reoperated for pulmonary autograft dilatation (n=3) and for leaflet fibrosis or perforation (n=2). Autografts were repaired in two patients, while a mechanical valve was inserted in 3 cases. At 9 years the actuarial survival and event free survival were 89 and 74%, respectively. At last follow-up 90% of autograft diameters indexed to body surface area was above the 90th percentile of normal aortic root diameters. LVOT and RVOT gradients were low and autograft insufficiency was trivial to mild in 84% and mild to moderate in 16%. Autograft stenosis was not noticed. Conclusions: The pediatric Ross procedure remains an important tool but autograft dilatation also occurs in the pediatric population. The significance of this finding has yet to be determined.     

心外管道全腔静脉肺动脉吻合术治疗复杂性先天性心脏病

目的 评价心外管道全腔静脉肺动脉吻合术(TCPA)治疗复杂先天性心脏病的临床应用价值。方法 1998年6月～2002年7月，26例先天性心脏病复杂畸形的患者接受了心外管道TCPA，包括单心室伴完全型大动脉转位16例，三尖瓣下移畸形2例，右心室双出口伴大动脉转位3例，三尖瓣闭锁伴右心室发育不良5例。19例在全身麻醉低温体外循环下手术，7例在非体外循环下手术。结果 无手术死亡，全部患者治愈出院。术后随访1～47个月，无晚期死亡。所有患者症状消失，无静脉压明显升高现象，超声心动图检查示心外管道血流通畅，无血栓形成，心电图检查示无严重的心律失常，血氧饱和度0．93～0．96，心功能均达Ⅰ～Ⅱ级。结论 心外管道TCPA是一种较为简单的手术方式，易于掌握；术后疗效满意，优于其他术式。     

Evaluation of septal insertion of atrioventricular valves in fetuses by postmortem 4.7 Tesla cardiac MRI: A feasibility study

Purpose

The purpose of this study was to compare non-invasive high-spatial-resolution postmortem cardiac magnetic resonance imaging (MRI) and autopsy findings for evaluating the septal insertion of atrioventricular valves in fetuses.

Long-term results of valve replacement using antibiotic-sterilised homografts in the aortic position

Objective.

Antibiotic-sterilised homograft valves stored at 4 °C have been implanted in the subcoronary position in this unit since 1973. This study was undertaken in order to assess the longterm function of these valves.

Methods.

All 249 patients undergoing homograft aortic valve replacement (AVR) at the Wessex Cardiothoracic Centre between April 1973 and December 1994 were studied. Homograft valve sizes ranged from 15 mm to 28 mm internal diameter, 202 (81.1%) varying between 18 mm and 22 mm. The mean patient follow-up was 12.4 years with a total follow-up of 3096 patient-years. There were six early deaths (2.4%).

Results.

On actuarial analysis, survival was 78.5 ± 2.7% (1SE) at 10 years, 65.7 ± 3.3% at 15 years and 55.0 ± 3.9% at 20 years. The freedom from redo AVR was 87.9 ± 2.4% at 10 years, 71.7 ± 3.8% at 15 years and 49.7 ± 5.6% at 20 years. The freedom from structural degeneration was 85.5 ± 2.5% at 10 years, 63.6 ± 4.0% at 15 years and 41.9 ± 6.4% at 20 years. On multivariate analysis the risk of valve failure was significantly higher in younger patients (P < 0.0001) and in those who underwent aortic root tailoring (P = 0.024). The freedom from endocarditis was 98.4 ± 0.9% at 10 years, 96.2 ± 1.6% at 15 years and 95.1 ± 1.9% at 20 years. Of the 249 patients, 218 had an isolated homograft AVR and were not anticoagulated. In this group there were two possible thromboembolic events.

Conclusion.

As well as the established haemodynamic benefits, this study has shown that homograft AVR with antibiotic-sterilised 4 °C stored homograft valves implanted in the subcoronary position, offers good long-term results.     

Tissue engineered heart valves: autologous cell seeding on biodegradable polymer scaffold

We previously reported on the successful creation of tissue-engineered valve leaflets and the implantation of these autologous tissue leaflets in the pulmonary valve position. Mixed cell populations of endothelial cells and fibroblasts were isolated from explanted ovine arteries. Endothelial cells were selectively labeled with an acetylated low-density lipoprotein marker and separated from fibroblasts using a fluorescent activated cell sorter. A synthetic biodegradable scaffold consisting of polyglycolic acid fibers was seeded first with fibroblasts then subsequently coated with endothelial cells. Using these methods, autologous cell/polymer constructs were implanted in 6 animals. In 2 additional control animals, a leaflet of polymer was implanted without prior cell seeding. In each animal, using cardiopulmonary bypass, the right-posterior leaflet of the pulmonary valve was resected completely and replaced with an engineered valve leaflet with (n = 6) or without (n = 2) prior cultured cell seeding. After 6 h and 1, 6, 7, 9, and 11 weeks, the animals were sacrificed and the implanted valve leaflets were examined histologically, biochemically, and biomechanically. Animals receiving leaflets made from polymer without cell seeding were sacrificed and examined in a similar fashion after 8 weeks. In the control animals, the acellular polymer leaflets were degraded completely leaving no residual leaflet tissue at 8 weeks. The tissue-engineered valve leaflet persisted in each animal in the experimental group; 4-hydroxyproline analysis of the constructs showed a progressive increase in collagen content. Immunohistochemical staining demonstrated elastin fibers in the matrix and factor VIII on the surface of the leaflet. The cell labeling experiments demonstrated that the cells on the leaflets had persisted from the in vitro seeding of the leaflets. In the tissue-engineered heart valve leaflet, transplanted autologous cells generated proper matrix on the polymer scaffold in a physiologic environment at a period of 8 weeks after implantation.     

Late results of the peel operation for replacement of failing extracardiac conduits

BACKGROUND: Pulmonary ventricle to pulmonary artery conduits have made repairing many complex congenital cardiac anomalies possible. Late patient outcome is adversely affected by the hemodynamic consequences of conduit failure and the need for reoperation for conduit replacement. METHODS: We retrospectively reviewed 102 patients (65 males, 37 females) who underwent operation with autologous tissue reconstruction ("peel operation") between May 1983 and November 2001, in which a prosthetic roof was placed over the fibrous bed of the explanted conduit. Ages ranged from 5 to 58 years old (median age 19 years old). Explanted conduits were Hancock (n = 54), homograft (n = 21), Tascon (n = 11), and other (n = 16). The conduit roof was constructed with pericardium (n = 91) and other (n = 11). A prosthetic pulmonary valve was utilized in 68 patients: porcine in 65 patients and mechanical in 3 patients. A nonvalved reconstruction was performed in 34 patients. Concomitant cardiac procedures were performed in 66 patients. RESULTS: Early mortality overall was 2% (n = 2) and was 0% for patients who underwent isolated conduit replacement (n = 36). Mean follow-up was 7.6 years (maximum, 19 years). Overall survival at 10 and 15 years was 91% (84.7, 97.2) and 76% (62.8, 91.7), respectively. Nine patients required reoperation related to the peel operation: regurgitation in nonvalved conduit (n = 7); moderate pulmonary bioprosthesis stenosis and regurgitation with atrial arrhythmia (n = 1); and pulmonary bioprosthesis endocarditis (n = 1). Overall survivorship free of reoperation for peel reconstruction failure at 10 and 15 years was 90.7% (82.6, 99.6) and 82% (69.4, 97.0), respectively. Survivorship free of reoperation for patients with a prosthetic valve was 93.7%, and for those with no prosthetic valve was 80.0% at 15 years (p = 0.57). At late follow-up, 89% of patients were in New York Heart Association functional class I or II. CONCLUSIONS: The peel operation simplifies conduit replacement, can be performed with low risk, and provides a generous-sized flow pathway. In our experience late results demonstrate a lower freedom from reoperation than conventional prosthetic or homograft conduits.     

Reconstruction of the RVOT with valved biological conduits: 25 years experience with allografts and xenografts

Objective: The reconstruction of the RVOT in congenital heart disease often requires the implantation of a valved conduit. Although allografts are considered the conduit of choice their availability is limited and therefore xenografts are implanted as well. We compared the long-term durability of both grafts in the RVOT over a 25-year period. Methods: Between January 1974 and August 1999, 505 patients (median age 4.0 years, range 2 days–31 years; median weight 14.5 kg, range 2.2–76.6 kg; median body length 103 cm, range 48–183 cm) with congenital malformations (PA 25.3%, TOF 14.5%, TOF+PA 2.4%, DORV 4.2%, TGA+PS 8.7%, TAC 24.8%, and other 20.2%) received their first valved conduit (174 xenografts: median diameter 14 mm, range 8–27 mm; 331 allografts: median diameter 19 mm, range 8–30 mm). Results: Follow-up is 3017 patient-years. The 10-year survival-probability for all patients. was 66% with a mean reoperation-free interval for conduit-exchange of 13.3 years (mean reoperation-free interval for allografts, 16.0 years; mean reoperation-free interval for xenograft, 10.3 years). One hundred and thirteen patients underwent a conduit-exchange, mostly due to conduit stenosis. Fourteen patients had a second exchange and three patients a third exchange. For patients with conduit diameters <18 mm (n=235: allograft n=116, xenograft n=119; median age 9 months, range 0–27.3 years), the mean reoperation-free interval was 11.2 years (mean interval allograft, 13.1 years; mean interval xenograft, 8.6 years, P=0.03). For conduit diameters ≥18 mm (n=270: allograft n=215, xenograft n=55, median age 7.4 years, range 0–34.3 years) the mean interval from freedom of conduit exchange was 15.1 years (for allografts 14.1 years, for xenografts 12.5 years, P<0.01). Comparing xenografts to allografts, we found no difference in patient survival probability (P=0.62). There was no significant difference between antibiotic (n=198) preserved vs. cryopreserved (n=133) allografts (P=0.06). Blood group compatibility of allografts to recipients had no significant influence on allograft function (P=0.42). The donors allograft origin, whether aortic or pulmonary valve, had also no significant influence on allograft long-term function (P=0.15). Conclusion: For the reconstruction of the right ventricular outflow tract (RVOT) allografts show significantly better long-term durability than xenografts regardless of the age at implantation and the diameter.     

Characterization of antithrombotic activity of lumbrokinase-immobilized polyurethane valves in the total artificial heart

Thirty ng/mm2 lumbrokinase, a potent fibrinolytic enzyme, was immobilized in a Korean type total artificial heart (KORTAH) valve by photoreaction; polyallylamine was used as a photoreactive linker. Lumbrokinase-immobilized polyurethane valves were then fitted to the total artificial hearts of 3 healthy 50 kg lambs. In the control lamb, the valves were untreated; in one other, only valves on the right were treated; and in the remaining animal, only those on the left. Implants were in place for up to 3 days, and cardiac output was 5 L/min. To facilitate thrombus formation, low doses of heparin were administered. In the control lamb, thrombi was observed only in the inlet parts of the valves. In the other 2 experiments, thrombi formed in untreated control valves but not in lumbrokinase treated valves. The grade of thrombus formation in untreated valves was 1.06+/-1.37 versus 0+/-0 in the treated part by one-sided Student's t-test (p < 0.1). After implantation, fibrinolytic activity was only observed in treated valves by fibrin plate methods. The proteolytic activity of the treated valves was 3 times higher than that of untreated valves using the azocasein method. These data show that lumbrokinase treated polyurethane valves lead to decreased thrombus formation in vivo and that their biocompatibility is therefore greater than that of untreated valves.     

Rates of cycling cells in cryopreserved valvular homograft: a preliminary study

Some investigators claim that the viability of cryopreserved human valvular homograft is necessary for the duration of implanted homograft. In this preliminary study, the percentage of cycling cells in cryopreserved valvular homografts was evaluated with the use of monoclonal Ki-67 antibody. Three human aortic valves were harvested from multiorgan donors and cryopreserved. Sections of 5 microm in thickness were stained with monoclonal Ki-67 antibody. The proportion of endothelial cells with Ki-67 positive nuclei was 1.80 +/- 0.20%. No differences in distribution were observed from basal to marginal sites. Few fibroblasts showed Ki-67-immunopositivity (0.10 +/- 0.06%) while the Ki-67 immunostaining was 0.80 +/- 0.20% in myocytes. Our preliminary study shows that cryopreserved valvular homograft cells are not only viable but they also have the potential to replicate. These data can lead to the hypothesis that valvular cells could actively replicate even after implantation, permitting cellular renewal and regeneration of extracellular matrix's components.     

Long-term results of porcine bioprosthetic valves

Between November 1977 and October 1980, 54 patients underwent valve replacements with porcine bioprostheses at Hyogo Kenritsu Amagasaki Hospital. The late complications and the long term durability of 53 porcine bioprostheses were documented in 48 patients after discharge (34 mitral, 7 aortic, 2 tricuspid, and 5 multiple, consisting of 38 Hancock, 15 Carpentier-Edwards prostheses). Cumulative duration of follow-up is 420 patient-years. The valve related late mortality was 0.52%/patient-years. There were 6 thromboembolic events (1.6% patient-years), only 1 episode of endocarditis (0.26%/patient-years). Valve dysfunction is defined as stenosis or regurgitation by echocardiogram or cardiac catheterization. There were 21 instances of porcine bioprosthetic dysfunction (6.6% patient-years). Freedom from valve dysfunction at 12 years was 24.4%. There were 17 valves of mitral bioprosthetic dysfunction (6.4% patient-years). The incidences of mitral stenosis (MS), mitral regurgitation (MR), and paravalvular leakage were 4.5, 3.6, and 0.7%/patient-years respectively. Freedom from MR was higher than MS at 8 years. The 14 patients were needed reoperation due to valve dysfunction (3.6%/patient-years). We concluded that the porcine bioprostheses showed a high incidence of valve dysfunction at 7 to 8 years after operation, we presently choose mechanical valve in most cases.     

Long-term results with vein homograft in femoro-distal arterial reconstructions

There still is a need for an alternative to autologous vein especially for infra-inguinal vascular reconstructions. Since 1984 we have used a denatured venous homograft in patients in whom the saphenous vein was either absent or unsuitable. One hundred and five homografts were implanted in the femoro-popliteal and 51 in the femoro-infrapopliteal position. The results obtained were satisfactory, with a 5-year cumulative patency (life-table method) of 53% overall, 68.4% in patients with disabling claudication, and 42% in those with critical ischaemia. The cumulative aneurysm rate was rather high, at 18% after 3 years and 58% after 5 years. An excellent limb salvage rate of 85% was achieved in patients with critical ischaemia. The management of graft aneurysms and the indications for reconstructive surgery with a denatured venous homograft are discussed.     

Long-term outcome of pediatric renal transplantation in boys with posterior urethral valves

Purpose

To determine whether there is a difference in the outcome of renal transplantation (RT) in patients with posterior urethral valves (PUV) and children with non-uropathy related end stage renal disease.

Redo aortic root surgery for failure of an aortic homograft is a major technical challenge

OBJECTIVE: Aortic homografts offer many advantages over prosthetic valves. However, homograft dysfunction due to degeneration or infection may lead to reoperation. Aortic valve replacement in patients who have undergone previous aortic root replacement with an aortic homograft remains a technical challenge. To assess reoperation events a retrospective review was conducted. MATERIALS AND METHODS: From January 2000 to October 2006, 20 consecutive patients (38.8+/-14.9 years old) underwent repeat surgery for aortic homograft failure. RESULTS: Reoperation was performed 7.2+/-3.5 years after implantation of the aortic homograft as a root. Indication was homograft degeneration (n=18 [90%]) and endocarditis (n=2 [10%]). In patients with major homograft wall calcifications or endocarditis, nine aortic root reconstructions were performed (Bentall procedure n=7; homograft implantation n=2). Each homograft was dissected with electrical cauterization and removed 'en-bloc' sparing the coronary buttons. In case of flexible homograft wall, stented prostheses (mechanical n=10, bioprosthesis n=1) were implanted along the homograft annulus. Additional procedures consisted of mitral valve replacements (n=8), tricuspid repairs (n=4), Konno procedure (n=1) and coronary bypass (n=5). Perioperative complications occurred in seven (35%) patients: sternal re-entry accident (n=2); reoperations for mediastinitis (n=1) or bleeding (n=2); renal insufficiency (n=1); total heart block (n=1). No association was found between operative procedures and postoperative complications (Fisher's exact test). Two patients (10%) died from multiorgan failure in the early postoperative period. In total, 94.4% of the survivors remained free from reoperation at 74 months. CONCLUSION: Reoperation on patients with an aortic homograft as a root presents a relatively high perioperative morbidity. The surgical strategy depends on the degree of homograft wall calcification.