Comparative analysis of mechanical and bioprosthetic valves after aortic valve replacement

Comparative long-term performance characteristics of Bj?rk-Shiley mechanical and bioprosthetic valves were analyzed for patients undergoing aortic valve replacement between 1976 and 1981. A total of 419 patients received either a standard Bj?rk-Shiley (n = 266) or bioprosthetic (porcine, n = 126, or pericardial, n = 27) aortic valve. Cumulative patient follow-up was 1,705 patient-years; the average patient follow-up was 4.1 +/- 2.7 years. Survival data were obtained for all but 11 patients (97% complete follow-up) up to 9 years after operation. Survival at 5 years was 81% +/- 4% (+/- standard error) for Bj?rk-Shiley and for bioprosthetic valve recipients. Valve failure in the Bj?rk-Shiley group was predominantly due to valve-related mortality and did not result from structural failure. Patients with bioprosthetic valves experienced valve failure as a result of prosthetic valve endocarditis and intrinsic valve degeneration. Although patients with bioprostheses experienced a lower incidence of valve-related morbidity than Bj?rk-Shiley valve recipients (p less than 0.03), no difference could be demonstrated in the incidence of valve-related mortality or valve failure at 5 years between bioprosthetic and Bj?rk-Shiley valves. Mortality rate from valve failure was higher for Bj?rk-Shiley (86%, 12/14) than bioprosthetic valves (36%, 5/14) (p less than 0.01).     

Actuarial analysis of the risk of prosthetic valve endocarditis in 1,598 patients with mechanical and bioprosthetic valves

We reviewed the charts of 1,598 patients undergoing valve replacement at the National Institutes of Health, Bethesda, Md, from 1956 through 1981. Retrospective analysis disclosed that 43 patients had prosthetic valve endocarditis (PVE). Twelve patients had early (less than 60 days after operation) and 31 patients had late (greater than 60 days after operation) endocarditis. The cumulative risk was 3% at five years and 5% at ten years. We also calculated the interval risk of PVE. The high risk of early PVE development peaked 15 days after operation. The peak risk was 45 episodes per 100,000 patient days. The risk then declined rapidly and from 150 days to 20 years remained stable at approximately one episode per 100,000 patient days. Nine hundred fifty-two patients had valve replacement with a Starr-Edwards prosthesis and 363 patients had valve replacement with a bioprosthetic valve; there was no significant difference in the risk of PVE in either group. Neither the valve make, position, model, nor the number of valves implanted affected the frequency of PVE or the mortality. Actuarial techniques disclosed the high early risk of PVE, the prolonged risk of PVE up to 150 days after operation, and the low but persistent risk late after operation. There was no significant difference in the risk of PVE in patients with bioprosthetic v mechanical valves.     

Comparative analysis of isolated aortic valve replacement with fascia lata and homograft valves

Thirty-eight consecutive patients who underwent isolated replacement of the aortic valve with fascia lata in 1970 were compared with a similar series of patients undergoing homograft replacement of the aortic valve. These series were well matched in number, age sex of patients, symptomatology, valvular disease, electrocardiographic and roentegenographic changes, and preoperative cardiac catheterization data. The mean follow-up time was 73 months in the fascia lata series and 69.1 months in the homograft series, and all the post-operative survivors were reviewed. The early and long-term results were similar of the two series, and there was no statistical difference in the operative and late mortality, the incidence of early and late diastolic murmurs, valve failure necessitating valve replacement, infective endocarditis, thromboembolism, over-all survival, and survival with an intact valve. It is concluded that the long-term results of valve replacement using these two tissues, in the aortic position, are similar and there is little to choose between the two types of valves. If fascia lata, as we believe, is no longer acceptable as a satisafactory valve substitute, then homograft valves are not acceptable either.     

心脏瓣膜置换术后低强度抗凝研究

目的　研究我国南方地区人工机械瓣膜置换术后行低强度抗凝的可行性及安全强度。方法　75例置换人工机械瓣膜的患者按国际标准化比值(INR)分为A、B、C 3组。术后定时分别检测其凝血酶原时间(PT)及INR、D 二聚体浓度、抗凝血酶Ⅲ活性(AT Ⅲ:C) ,并定时监测术后出血及血栓形成的发生率。结果　机械瓣膜置换术后,INR控制于1.6～2 .5范围,可保持D 二聚体浓度、AT Ⅲ:C与对照组差异无统计学意义(P >0 .0 5 )。2 5 5人次INR控制1.6～2 .5之间,3组均未出现血栓形成,有16人次轻微出血,其中A组有4人次(4 /15 5 ,2 .5 % ) ;B组有5人次(5 /70 ,7.1% ) ;C组有7人次(7/3 0 ,2 3 .3 % ) ,明显高于A、B两组(P <0 .0 1)。结论　我国南方地区人工机械瓣膜置换术后低强度抗凝是可行的,INR控制在1.6～2 .5范围较安全。     

保留瓣下结构对二尖瓣置换术后机械瓣血流动力学的影响

目的探讨保留瓣下结构对二尖瓣置换术(MVR)后机械瓣血流动力学的影响. 方法对100例二尖瓣狭窄为主的患者施行MVR,根据术中对自体瓣膜处理的方式不同分为全部保留瓣下结构组(Ⅰ组、23例),全部切除瓣下结构组(Ⅱ组、27例),保留前瓣组(Ⅲ组、22例),保留后瓣组(Ⅳ组、28例),20例健康志愿者作为正常组.均采用二维超声心动图、彩色多普勒技术,对各组患者随访,以正常人作为对照,测量二尖瓣口血流动力学参数,比较各组间的差别. 结果Ⅰ～Ⅳ组二尖瓣口血流动力学的各种参数与正常组比较差别具有显著性意义(P＜0.05),而各种参数在Ⅰ～Ⅳ组之间比较差别无显著性意义(P＞0.05). 结论在慢性二尖瓣狭窄为主的患者中,研究涉及的各种保留瓣下结构方法之间,保留与不保留瓣下结构之间,术后中期的机械瓣血流动力学无明显差别.     

Comparison of survival after mitral valve replacement with biologic and mechanical valves in 1139 patients

OBJECTIVE: We sought to compare 10-year survival in patients after mitral valve replacement with biologic or mechanical valve prostheses. METHODS: Retrospective survival analysis was performed on data from 1139 consecutive patients older than 18 years of age undergoing mitral valve replacement with Carpentier-Edwards (n = 495; Baxter Healthcare Corp, Irvine, Calif) or St Jude Medical (n = 644; St Jude Medical, Inc, St Paul, Minn) prostheses. RESULTS: The 10-year survival was not statistically different between the patients receiving Carpentier-Edwards valves and those receiving St Jude Medical valves (P =.16). Adjusted survival estimates at 2, 5, and 10 years were 82% +/- 2% (95% confidence intervals, 79%-85%), 69% +/- 2% (95% confidence intervals, 64%-73%), and 42% +/- 3% (95% confidence intervals, 37%-48%), respectively, for the Carpentier-Edwards group and 83% +/- 2% (95% confidence intervals, 80%-86%), 72% +/- 2% (95% confidence intervals, 69%-76%), and 51% +/- 3% (95% confidence intervals, 45%-58%), respectively, for the St Jude Medical group. Predictors of worse survival after mitral valve replacement are older age, lower ejection fraction, presence of class IV congestive heart failure, coronary artery disease, renal disease, smoking history, hypertension, concurrent other valve surgery, and redo heart surgery. CONCLUSION: Choice of biologic or mechanical prosthesis does not significantly affect long-term patient survival after mitral valve replacement.     

Bovine pericardium versus porcine aortic valve: comparison of tissue biological properties as prosthetic valves

The choice of a bioprosthetic valve substitute remains controversial with the major concern being primary tissue failure after implantation. We compared biological properties of the two most frequently used bioprosthetic valve materials, bovine pericardium and porcine aortic valve, before and 90 days after subcutaneous implantation in rats. Before implantation, tissue collagen and water content were measured in nine pieces of bovine pericardium and porcine valves, each fixed in 0.625% glutaraldehyde; calcium, tissue collagen, and water content were measured in another nine pieces of the same tissues after 90 days' implantation. Bovine pericardium had higher collagen content than that of porcine valve (hydroxyproline, 7.98 +/- 0.05* vs. 4.56 +/- 0.02 micrograms/mg, dry weight) but lesser water content (72.16 +/- 3.22%* vs. 87.36 +/- 1.62%) before implantation (*p < 0.001, mean +/- SD, t test); after implantation, bovine pericardium still maintained higher collagen content (hydroxyproline, 4.89 +/- 0.04* vs. 2.61 +/- 0.06 micrograms/mg, dry weight) but contained the same amount of water (60.24 +/- 5.08% vs. 61.43 +/- 9.00%) and calcium (214.43 +/- 34.34 vs. 199.33 +/- 53.44 micrograms/mg, dry weight) (*p < 0.001, mean +/- SD, t test). We conclude that bovine pericardium has superior intrinsic biological properties for prosthetic valve manufacture. With proper integration of properties and design it will in some applications be superior to the porcine aortic valve.     

Long-term clinical results after aortic valve replacement with mechanical heart valves and mitral valve replacement with porcine valves]

Long-term clinical results of aortic valve replacement (AVR) with mechanical heart valves and mitral valve replacement (MVR) with porcine valves were analysed. Sixty-three patients received isolated AVR and 48 received isolated MVR. Sixty-eight patients with MVR including double or triple valve replacement were also added in order to evaluate the primary tissue failure (PTF). The patients with operative deaths were excluded. Survival rate at 11 years in AVR was 68 +/- 10% and 67 +/- 15% in MVR without statistical difference. At 11 years, 76 +/- 8% of the patients in AVR were free from valve-related complications in contrast with the poor result of 34 +/- 31% in MVR (p less than 0.01). Main cause of this poor result in MVR was PTF as indicated in following event free rates; 83 +/- 9% at 7 years, 61 +/- 25% at 10 years and 49 +/- 31% at 13 years. There was no statistical difference between patients of above 50 years and below 49 years in PTF. Valve-related death event free was 93 +/- 5% in AVR and 86 +/- 11% in MVR at 11 years (not significant), however, there was statistical difference in re-operation event free rate as 94 +/- 5% in AVR and 76 +/- 11% in MVR at 11 years (p less than 0.001). These results suggest that the use of porcine valves in mitral position is confined to the selected patients.     

Clinical assessment of prosthetic valve replacement of the right-sided cardiac valves: mechanical or bioprosthesis?

Clinical results with mechanical and bioprosthetic valve replacements for tricuspid and/or pulmonary positions were reviewed. Between February 1975 and December 1985, 34 bioprostheses (B) (22 Hancock, 9 Ionescu-Shiley and 3 Carpentier-Edwards pericardial) and 18 mechanical prostheses (M) (St. Jude Medical) were implanted in our institute excluding hospital death. Group with B included 29 tricuspid valve replacements and 5 pulmonary valve replacements. Group with M included 9 tricuspid valve replacements, 7 pulmonary valve replacements and 1 both valve replacements. The cumulative follow-up period was 207.2 patient-years (p-t) in group B and 55.0 p-y in group M. The incidence of valve failure was 0.48 +/- 0.48% per p-y in group B and 7.27 +/- 3.64% per p-y in group M (p less than 0.001). The incidence of valve-related events was 1.93 +/- 0.97% per p-y in group B and 9.09 +/- 4.07% per p-y in group M (p less than 0.001). At 3 years, the percent free of valve failure was 100 +/- 0% in group B and 76.8 +/- 10.2% in group M (p less than 0.05). Fourteen bioprosthetic valves (B') and 10 mechanical valves (M') were implanted at the right-sided cardiac valve position alone. The cumulative follow-up period was 94.2 p-y in group B' and 32.3 p-y in group M'. The incidence of valve-related events was 1.06 +/- 1.06% per p-y in group B' and 12.4 +/- 6.19% per p-y in group M' (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)     

主动脉机械瓣膜置换术后低强度抗凝研究

目的探讨人工机械主动脉瓣膜置换术后行低强度抗凝的可行性及安全强度。方法85例主动脉机械瓣膜置换的患者，按国际标准化比值（INR）分为A、B两组，定时分别检测其INR、D-二聚体浓度与抗凝血酶Ⅲ活性（AT—Ⅲ：C），并定时监测术后出血及血栓形成的发生率。结果两组术后AT-Ⅲ：C分别与对照组差异均无统计学意义（P〉0．05）。D-二聚体与对照组比较B组增高，A组无明显变化，A、B两组间差异有统计学意义（P〈0．05）。两组均出现临床轻微出血现象（牙龈出血、眼睑或皮下紫瘢），其中A组4人次（4／50），B组3人次（3／35）。A组无一例出现栓塞，B组中3例患者出现单侧肢体轻微栓塞现象。结论我国南方地区主动脉瓣人工机械瓣膜置换术后行较低强度抗凝治疗是可行的，INR值控制在1．5—1．8范围较安全。     

心脏机械瓣膜置换手术前后生活质量的对比研究

目的针对我国瓣膜病人的特点，对比研究换瓣手术前后生活质量变化。方法1998年2月至6月对115例人工心脏机械瓣膜置换病人进行手术前后生活质量变化的对比研究。结果换瓣手术后病人体力活动能力较手术前明显改善，尤其户外活动能力较手术前明显改善，日常生活能力增强。手术后84％病人恢复患病前的心情，其术后的孤独、压抑、焦虑和紧张评分较术前明显减低，性生活和脾气急躁较术前也明显改善。术后病人的家庭生活、社会关系及工作生活等方面较术前明显改善(P=0．000)。64％有瓣膜相关损害的病人认为在当地购买抗凝药物不方便，而无并发症病人仅为39％，两组有明显差异(P=0．034)；担心服用抗凝药物导致出血方面，有并发症病人肯定回答显著高于无并发症病人(86％对55％，P=0．006)。结论人工心脏机械瓣膜置换手术可显著改善心脏瓣膜病病人生活质量。应降低人工瓣膜相关并发症发生率。     

血栓前体蛋白对瓣膜置换术后血栓形成的意义

目的 探讨血栓前体蛋白(TpP)对监测机械瓣膜置换术后血栓形成的意义。方法 分别测定19例瓣膜置换术在术前、术后2h、第1、2、3天外周静脉血TpP、D—二聚体(D—Dimer)、纤维蛋白原含量。结果 TpP含量术前处于正常水平，术后逐渐升高，2h达高峰，然后缓慢下降，第3天再次升高(P＜0．01)；D-Dimer含量术后2h、第1、2、3天明显增加(P＜0．01)，呈持续高水平；纤维蛋白原含量术后先降低后升高，第2天超过正常水平；瓣膜置换合并冠脉搭桥术后2h和第1天TpP含量比单纯瓣膜置换术升高。结论 瓣膜置换术后早期机体存在活动性血栓形成倾向，检测TpP对指导术后抗凝有一定价值。     

Intermediate-term results after the aortic valve replacement using bileaflet mechanical prosthetic valve in children.

OBJECTIVE: Intermediate/long-term results after aortic valve replacement using bileaflet mechanical valve in children should be clarified as a standard of treatment of aortic valve disease in children. METHODS: Forty-five patients aged under 15 years underwent 46 aortic valve replacements using bileaflet mechanical prosthetic valve. Patients' ages ranged from 1 to 15 years (9 years as a median value), and follow-up period was 9.2 years as a median value (maximum 19 years). RESULTS: In situ valve replacement was performed in 21 procedures, while annular enlargement was required in 25 procedures (Nicks 10, Yamaguchi 3, Manouguian 2, Konno 10). All patients except two received prosthesis 19mm or larger in size. There was one operative death and two late deaths. Two episodes of cerebral infarction, two valve thrombosis, two re-operations, one infective endocarditis, and one sudden death were recognized as valve-related complications in five patients. The reasons for re-operation were prosthesis-patient mismatch in one (Ross procedure) and valve thrombosis in one (re-replacement). At 15 years after the operation, re-replacement free rate, valve-related event free rate and actuarial survival rate were 94+/-4%, 86+/-6% and 92+/-4%, respectively. The transprosthetic flow velocity estimated by Doppler echocardiography at the final follow-up was well correlated with manufactured valve area index (cm(2)/body surface area). CONCLUSIONS: Although aortic annular enlargement was required in more than half of the cases, intermediate-term results after aortic valve replacement using bileaflet mechanical prosthetic valve in children was satisfactory. Indications for alternative treatment such as Ross procedure might be considered in limited cases.     

国产双叶机械瓣长期存活动物模型的建立

目的　建立瓣膜置换动物长期存活的模型 ,使人工心脏瓣膜各项指标的评估成为可能。　方法　小尾寒羊 6只 ,平均体重 4 7kg,术前均经过灭虫、圈养处理 ,禁食 2 4小时 ,禁饮 8小时 ,严格无菌条件下 ,全身麻醉气管内插管 ,常温体外循环下 ,在羊肺动脉瓣位置植入 2 1#国产双叶机械瓣 ,术前、术中和术后常规应用青霉素抗感染治疗 ;术后监测全血激活凝血时间 (ACT)调节肝素用量 ,使 ACT维持在 30 0± 5 0秒左右 ,进食后改口服华法林抗凝 ,国际标准化比值 (INR)控制在 3.0～ 4 .0之间。　结果　 6只羊均存活并超过 3个月 ,存活最长的 1只已达 6个月 ,无 1只出现感染、栓塞等并发症 ,且状态良好。　结论　经过严格的无菌操作、抗菌素应用和抗凝治疗 ,应用国产小尾寒羊 ,可建立良好的评估机械瓣功能的长期存活实验动物模型。