儿童心脏瓣膜置换手术技巧及效果

目的 总结1999年9月至2006年9月14例儿童心脏瓣膜置换术的经验。探讨儿童瓣膜置换的手术指征、辩膜选择、手术技术和术后抗凝治疗等问题。方法 全组14例中10例为先天性心脏瓣膜病变，3例风湿性病变，1例先天性室间隔缺损致心内膜炎、主动脉瓣膜菌栓。在中低温体外循环下手术，二尖瓣置换7例，主动脉瓣置换6例，二尖瓣置换＋主动脉瓣置换1例。均采用机械瓣。若合并其它先天性心脏畸形或三尖瓣关闭不全，同期矫治。术后常规应用华法林抗凝。结果 本组手术死亡1倒，12例心功能恢复至Ⅰ级，1例心功能Ⅱ级。发生1例感染性心内膜炎，治愈。均坚持采用华法林抗凝，无血栓栓塞及抗凝相关并发症发生，辩膜功能良好。结论 儿童心脏瓣膜置换术采用机械瓣效果较好；应用低强度的华法林进行抗凝治疗安全可靠。     

The CarboMedics prosthetic heart valve: experience with 180 implants

At Jichi Medical School Hospital, three types of mechanical prosthetic valves (CarboMedics, Omnicarbon, Bicarbon) were used without randomization from 1991 to 2000. A retrospective study of valve replacements done between June 1991 and November 2000 utilizing 180 CarboMedics valves in 145 patients who had not previously undergone prosthetic valve replacement or aortic root and/or arch replacement was conducted to evaluate midterm patient outcomes to assess the future continuous use of CarboMedics valves. Women made up 47.6% of the patients and the mean age was 57.5 years (range 12–80 years). Preoperative New York Heart Association functional class was III or IV in 92.4% (134/145) of patients. Mean follow-up of 4.5 years (range 0–10.0 years) was 95.9% complete, with a total of 628 patient-years (PY). Early (within 30 postoperative days) mortality was 5.5% (8 of 145): 3 from hemorrhage, 3 from nonvalve-related heart failure, 1 from infection, and 1 from arrhythmia. There were 16 late deaths (2.54%/PY): 1 from hemorrhage, 4 from unknown causes/sudden death, 4 from nonvalve-related heart failure, and 7 from other noncardiac causes. A total of 121 patients (83.0%) were alive at the last follow-up, done in November 2000. The linearized death rate was 3.82%/year (including 1.11%/year for valve-related deaths). Linearized death rates from various causes were: bleeding, 0.96%/year; thromboembolism, 1.11%/year; thrombosis, 0.39%/year; perivalvular leak, 0.96%/year; endocarditis, 0%/year; hemolysis, 0%/year; and reoperation, 0.63%/year. No structural valve failure was observed. Comparative early mortality rates of valve replacement without aortic root replacement or arch replacement, excluding repeat valve replacement operations, in our institute, were 3.5% (12/307) for all valve types used contemporaneously, 2.6% (2/76) for Omnicarbon valves, and 2.3% (2/86) for Bicarbon valves. Although the CarboMedics valve had a rather high mortality rate of 5.5% (8/145) compared with the total early mortality rate of 3.5%, the low incidence of valve-related complications might support the continued use of the CarboMedics valve for valve replacement.     

Isolated pulmonary valve replacement: analysis of 27 years of experience

The aim of this study was to investigate the longterm results of isolated pulmonary valve replacement using xenobioprostheses or mechanical valves. Twenty-four cases of isolated pulmonary valve replacement carried out at Kyushu University Hospital between 1977 and 2004 were reviewed. Those undergoing Rastelli's operation were excluded from this study. Bioprostheses were used in 18 patients and mechanical valves in 6. There were no operative deaths. Two patients with mechanical valves needed repeat pulmonary valve replacement due to thrombosed valves. The patients with bioprostheses had no need of repeat replacement postoperatively. The cardiothoracic ratio significantly improved from 60.3% preoperatively to 55.4% postoperatively (P < 0.05), and the New York Heart Association (NYHA) class significantly improved from 2.0 preoperatively to 1.1 postoperatively (P < 0.05). The actuarial survival rate at 15 years was 92.3%. The valve-related event-free ratio at 15 years was 85.7% in the bioprosthesis group and 66.7% in the mechanical valve group, with no significant difference. Isolated pulmonary valve replacement with bioprostheses or mechanical valves can be safely done and showed satisfactory long-term results. The mechanical valve group demonstrated a high ratio of thrombosed valves. A bioprosthesis is recommended for pulmonary valve replacement if a homograft is not available.     

Long-term results of mitral valve replacement: biological xenograft versus mechanical valves

 We studied 279 patients who underwent mitral valve replacement at the Department of Thoracic and Cardiovascular Surgery, Hyogo College of Medicine, between November 1973 and December 1998. The patients were divided into two groups based on the type of replacement valve (154 patients in the biological xenograft group and 125 patients in the mechanical valve group), and the long-term results were compared. Clinically satisfactory results were obtained in both the biological xenograft group and the mechanical valve group according to the surgical results, long-term survival, and incidence of prosthetic valve endocarditis. At 15 years, fewer patients in the mechanical valve group than in the biological xenograft group were free of bleeding events (92.5 ± 3.7% vs 100% P < 0.05). At 15 years, the biological xenograft group was lower than the mechanical valve group with respect to freedom from thromboembolism (72.2 ± 4.6% vs 93.5 ± 3.6% P < 0.01), freedom from valve failure (22.0 ± 5.2% vs 87.0 ± 4.1% P < 0.005) and freedom from cardiac events (16.5 ± 3.9% vs 47.2 ± 14.5% P < 0.01). Though it has previously been suggested that biological xenografts used in mitral valve replacement do not need anticoagulation, the current study suggests the need for anticoagulation with the use of biological xenografts. Mechanical valves require close monitoring of anticoagulation, but their use has decreased the incidence of valve failure and thromboembolism, as compared with the use of biological xenografts. Therefore, mechanical valves are currently the preferred choice for mitral valve replacement. We believe that biological xenografts are indicated only for the older patient (≧65 years). Received: August 1, 2002 / Accepted: October 28, 2002 Correspondence to:H. Yao     

Evaluation of coagulant activity after mechanical heart valve replacement

Long-term oral anticoagulant therapy is required for recipients of mechanical heart valves. In our hospital, the international normalized ratio of prothrombin time (PT-INR) has been set in the range 1.5–2.5 since October 2001. To evaluate whether coagulant activity is fully suppressed by this target range, coagulant activity was evaluated by measuring thrombin–antithrombin III complex (TAT) levels and valve-related complications were investigated retrospectively. Two hundred twenty-three patients who underwent mechanical valve replacement were enrolled in this study. PT-INR and TAT were measured at our outpatient clinic in March 2005 and valve-related complications since October 2001, when we started to control PT-INR in the range 1.5–2.5, were investigated. Under adequate warfarin control, there was no significant correlation between PT-INR and TAT, however nine patients who exhibited a PT-INR of less than 2.0 had high levels of TAT. And in atrial fibrillation (AF) patients after mitral valve replacement (MVR), the level of TAT was significantly high compared with sinus rhythm patients after atrial valve replacement. Valve-related complications were bleeding events at 2.75% per patient year and thromboembolism at 0.32% per patient year. Attention to complications of thromboembolism is necessary when the PT-INR is less than 2.0, especially in AF patients after MVR and in those with a thrombotic past history or high levels of TAT. The monitoring of TAT is useful in detecting potential coagulation factors and to determine the therapeutic range of warfarin that can normalize coagulant activity.     

Patient–prosthesis mismatch may be irrelevant after aortic valve replacement with the 19-mm Perimount pericardial bioprosthesis in patients aged 65 years or older

The prevalence of patient–prosthesis mismatch (PPM) and its influence on clinical midterm results were examined in elderly patients whose activity was supposed to be less than that of younger patients. We evaluated valve function and the effects of PPM on the midterm results of the 19-mm Carpentier–Edwards Perimount (CEP) pericardial aortic valve in patients aged 65 years or older. Between August 1996 and May 2005, 51 patients underwent aortic valve replacement with the 19-mm CEP valve. The mean follow-up was 2.4 ± 1.8 years, involving a total of 134.4 patient-years. The mean age and body surface area at operation were 74.0 ± 5.0 years and 1.41 ± 0.14 m². There were two (3.9%) operative deaths. Three patients (5.9%) underwent enlargement of their small aortic annuli. The actuarial survival rate at 8 years, including operative mortality, averaged 90.2% ± 4.7%. The freedom from thromboembolism, reoperation, and valve-related mortality averaged 75.0% ± 21.7%, 97.8% ± 2.2%, and 95.3% ± 3.2%, respectively, at 8 years. High preoperative peak and mean transvalvular pressure gradients were significantly improved after the operation (peak, 93 ± 35 versus 28 ± 12 mmHg; mean, 58 ± 19 versus 17 ± 7 mmHg, respectively; P < 0.01). The mean left ventricular mass index was reduced from 192 ± 44 to 142 ± 46 g/m² at late follow-up (P < 0.01). The prevalence of PPM was low (17.6%) when an indexed effective orifice area of less than 0.85 cm²/m² was taken as the definition of PPM. The clinical results, postoperative pressure gradients, and reduction in left ventricular mass index were not different between the PPM and no-PPM groups. The 19-mm CEP valve produced satisfactory midterm clinical outcomes in patients aged 65 years or older whose activity was supposed to be less than that of younger patients, regardless of the presence or absence of PPM. Moderate PPM was rare and it did not adversely impact on the midterm results. The application of annulus enlargement could be limited to the small number of patients for whom the 19-mm CEP valves are not able to be inserted.     

经心尖主动脉瓣置换术治疗高危单纯无钙化主动脉瓣关闭不全的手术配合

目的探讨国产J-Valve?支架瓣膜行经心尖主动脉瓣置换(TAVR)术治疗高危单纯无钙化主动脉瓣关闭不全的手术配合方法。 方法收集2017年3月至2018年3月在首都医科大学附属北京安贞医院高危单纯无钙化主动脉瓣关闭不全患者资料,共15例。所有患者均使用国产J-Valve?系统为患者行TAVR术。经过细致的术前评估(包括术前访视、熟悉仪器设备、介入耗材设备等)、术中流畅的手术配合[包括严格遵循无菌原则、术中患者体温保护、X线防护、激活全血凝固时间(ACT)的监测以及支架瓣膜的装配等]和术中安全管理(包括防止输送器移位和动脉置管的护理等)。观测患者术中是否使用心肺转流、发生心室快速起搏、中转行常规体外循环下TAVR术,是否有冠状动脉阻塞、植入瓣膜是否有移位,有无瓣膜内狭窄及瓣周漏等情况发生,观测术后即刻平均主动脉瓣跨瓣压差;患者在ICU是否顺利脱离呼吸机拔除气管插管,术中平均出血量、患者在ICU时间和呼吸机辅助通气时间、射血分数以及是否存在瓣周漏等;了解患者心功能分级、活动耐量以及是否存在胸闷、心绞痛等症状。 结果本研究中所有患者均成功完成TAVR术,未使用心肺转流、未发生心室快速起搏,无中转行常规体外循环下TAVR术,未发生冠状动脉阻塞或植入瓣膜移位,未见瓣膜内狭窄及瓣周漏等情况。术后即刻平均主动脉跨瓣压差为[5.8(4.9,12.9)] mmHg(1 mmHg＝0.133 kPa)。所有患者在ICU均顺利脱离呼吸机拔除气管插管,术中平均出血量为[200.0 (100.0, 500.0)]mL,患者在ICU时间为(1.2±0.4) d,呼吸机辅助通气时间为[19.0 (8.5, 23.5)] h,平均射血分数为(56.2±15.6)%,仅有2例患者存在微量瓣周漏。末次随访中,10例患者心功能Ⅰ级,4例为Ⅱ级,1例为Ⅲ级;患者的活动耐量都较术前明显改善;患者术后胸闷、心绞痛等症状较术前明显改善。 结论手术室护士正确掌握TAVR术的手术配合方法,术前做好患者的心理护理以及各项术前准备,手术过程中与外科医师密切配合,是患者手术成功的保证。     

Results of valve replacement surgery with mechanical prostheses

The clinical study is reported of the results of heart valve replacement surgery with a new pyrolytic carbon tilting disc prosthesis manufactured in Italy. From March 1977 to January 1981, at the "De Gasperis" Cardiosurgery Center, this prosthesis has been implanted in 644 patients: 283 for mitral valve replacement, 240 for aortic valve replacement, and 121 for the replacement of both mitral and aortic valves. To have a sufficiently long period of post-surgery follow-up, we considered the results of 207 patients (124 cases of isolated mitral valve replacement and 83 cases of isolated aortic valve replacement), who underwent surgery consecutively from March 1977 to December 1979. The hospital mortality was 10.5% for mitral valve replacement and 4.8% for aortic valve replacement. All patients who were discharged from hospital, except 2, were subjected to clinical, electrocardiographic, phonocardiographic, echocardiographic and radiological checks. The average follow-up period was approximately 20 months: clinical results were satisfactory. The probability of survival, expressed by actuarial curve, was, three years after surgery, 94% for patients who underwent mitral valve replacement and 97.5% for those who underwent aortic valve replacement. The probability of embolism was, three years after surgery, 8.5% for patients with mitral replaced and 5% for aortic. Even if further confirmations are needed the mortality rate and the probability of embolism related to this new prosthesis, are lower, over the same period of follow-up, than that found in the groups of patients who underwent valve replacement surgery, at the same Center, with Starr-Edwards and Bj?rk-Shiley prostheses. The phonocardiographic and echocardiographic characteristics of this new prosthesis were also investigated.     

Surgical management of mechanical valve thrombosis: twenty-six years' experience

In the present study, the authors investigated the management of mechanical valve thrombosis (MVT). From January 1981 through March 2006, 2,908 mechanical valve replacements were performed in 2,298 patients at our institution. Twenty (0.87%) patients presented with MVT, 14 (70.0%) were women, and the mean age of the patients was 42.0+/-14.0 (27-66) yr. Thrombosis involved mitral in 14 (70.0%), aortic in 2 (10.0%), tricuspid/aortic in 1 (5%), and tricuspid in 3 (15%). The interval from first operation to valve thrombosis was 121.8+/-75.4 (0.9-284.7) months. The most frequent clinical presentation was heart failure (13/20, 65%), and predisposing causes of MVT were: poor compliance with warfarin (7), pregnancy (5), drug interaction (2), and unknown (6). All 20 patients underwent valve replacement: mitral (14, 70.0%), tricuspid (3, 15.0%), aortic (2, 10%) and tricuspid/aortic (1, 5%). One early death occurred due to left ventricular failure, but no late mortality occurred during 63.3+/-49.9 (0.5-165.1) months of follow-up. MVT was treated successfully, and pregnancy and inadequate anticoagulation were found to influence the occurrence of this rare complication.     

Pannus formation in aortic valve prostheses in the late postoperative period

We present three patients who underwent repeat aortic valve replacement for prosthetic valve dysfunction caused by tissue ingrowth in the late postoperative period. These patients (three women aged 48–51 years, mean 49.3 ± 1.53 years) underwent operations for restriction of prosthetic valve leaflet movement by pannus in the left ventricular outflow tract. The interval from the previous operation ranged from 8.0 to 9.6 years (mean 9.6 ± 2.0 years). The symptoms of the patients were New York Heart Association functional class I, II, and IV in one patient each. Diagnosis was made by cinefluoroscopy in two patients and aortography in one patient. The operative procedures consisted of aortic valve replacement (n = 1) and aortic valve replacement with mitral valve replacement (n = 2). Pannus was found at the left ventricular aspect of the prosthetic valve in all patients. In two patients, the pannus directly restricted movement of the leaflet and also severely narrowed the inflow orifice of the prosthetic valve. In the other patient, the pannus had grown at a distance of 7mm from the valve and narrowed the left ventricular outflow tract circularly. The postoperative course was uneventful and all three patients were discharged in a good condition. One patient died of pneumonia 8 months after surgery and the other two patients have remained well and have been followed up for one and a half years. In conclusion, there may be a discrepancy between the clinical symptoms and the grade of subvalvular stenosis caused by pannus. Therefore, it is essential for satisfactory operative results that early diagnosis be made by various means.     

Pannus overgrowth after mitral valve replacement with a Carpentier-Edwards pericardial bioprosthesis

A Carpentier-Edwards pericardial (CEP) bioprosthesis was explanted from an 81-year-old woman due to nonstructural dysfunction 9 years after mitral valve replacement. The nonstructural dysfunction produced severe regurgitation in the mitral position. During the surgery, excessive pannus overgrowth was seen on the left ventricular side of the CEP bioprosthesis. Pannus overgrowth was prominent on one leaflet. That leaflet was stiff and shortened due to the excessive overgrowth of pannus. In this patient, the distortion of one leaflet was the main reason for transvalvular leakage of the CEP bioprosthesis in the mitral position. A new CEP bioprosthesis was implanted in the mitral position. Pathological analysis revealed fibrotic pannus with a small amount of cellular material over the leaflets of the resected CEP valve. This change was marked on the distorted leaflet.     

瓣膜置换术后发生血栓的病理学预测因素

目的对风湿性心脏病患者心腔血栓发生率和心肌病理改变进行相关性分析,探讨其发生心腔血栓的病理学基础,提出风湿性心脏病患者瓣膜置换术后发生心腔血栓的病理学预测因素。方法 103例风湿性心脏病患者,按照心腔血栓和心肌病理改变,经整理后形成2×2交叉分类资料。运用SPSS软件,进行两个分类变量间的关联分析,求出关联系数,并对相关系数进行χ2检验。结果在风湿性心脏病中,心腔血栓与心肌病理学改变是两个密切相关的因素,其相关系数为0.477,两者呈正相关关系（P〈0.05）。结论在瓣膜置换术中,常规进行左房病理组织学检查,如发现心肌细胞存在肌浆溶解、内膜增厚等改变,提示术后发生血栓危险性增加,可适当加强抗凝治疗强度。     

Successful matrix guided tissue regeneration of decellularized pulmonary heart valve allografts in elderly sheep

In vivo repopulation of decellularized allografts with recipient cells leads to a positive remodeling of the graft matrix in juvenile sheep. In light of the increasing number of heart valve replacements among older patients (>65 years), this study focused on the potential for matrix-guided tissue regeneration in elderly sheep. Pulmonary valve replacement was performed in seven-year old sheep using decellularized (DV), decellularized and CCN1-coated (RV), or decellularized and in vitro reendothelialized pulmonary allografts (REV) (n = 6, each group). CCN1 coating was applied to support re-endothelialization. In vitro re-endothelialization was conducted with endothelial-like cells derived from peripheral blood. Echocardiograms of all grafts showed adequate graft function after implantation and at explantation 3 or 6 months later. All explants were macroscopically free of thrombi at explantation, and revealed repopulation of the allografts on the adventitial side of valvular walls and proximal in the cusps. Engrafted cells expressed vimentin, sm α-actin, and myosin heavy chain 2, while luminal cell lining was positive for vWF and eNOS. Cellular repopulation of valvular matrix demonstrates the capacity for matrix-guided regeneration even in elderly sheep but is not improved by in vitro endothelialization, confirming the suitability of decellularized matrix for heart valve replacement in older individuals.     

Incidence and outcomes of infective endocarditis after transcatheter aortic valve implantation versus surgical aortic valve replacement

ObjectivesTranscatheter aortic valve implantation (TAVI) is an alternative to surgical aortic valve replacement (AVR) in aortic stenosis (AS). Infective endocarditis (IE) in patients with prosthetic heart valves is associated with significant morbidity and mortality. Data on the incidence, risk factors, and outcomes of IE after TAVI are conflicting. We evaluated these issues in patients with percutaneous TAVI vs. isolated surgical AVR (SAVR) at a nationwide level.MethodsBased on the administrative hospital discharge database, the study collected information for all patients with aortic stenosis treated with AVR in France between 2010 and 2018.ResultsA total of 47 553 patients undergoing TAVI and 60 253 patients undergoing isolated SAVR were identified. During a mean follow-up of 2.0 years (median (25th to 75th percentile) 1.2 (0.1–3.4) years), the incidence rates of IE were 1.89 (95% confidence interval (CI) 1.78–2.00) and 1.40 (95% CI 1.34–1.46) events per 100 person-years in unmatched TAVI and SAVR patients, respectively. In 32 582 propensity-matched patients (16 291 with TAVI and 16 291 with SAVR), risk of IE was not different in patients treated with TAVI vs. SAVR (incidence rates of IE 1.86 (95% CI 1.70–2.04) %/year vs 1.71 (95% CI 1.58–1.85) %/year respectively, relative risk (RR) 1.09, 95% CI 0.96–1.23). In these matched patients, total mortality was higher in TAVI patients with IE (43.0% 95% CI 37.3–49.3) than in SAVR patients with IE (32.8% 95% CI 28.6–37.3; RR 1.32, 95% CI 1.08–1.60).DiscussionIn a nationwide cohort of patients with AS, treatment with TAVI was associated with a risk of IE similar to that following SAVR. Mortality was higher for patients with IE following TAVI than for those with IE following SAVR.     

Results of randomized mitral valve replacement with mechanical prostheses after 15 years.

Between 1974 and 1976 150 consecutive patients (pts) were operated on for isolated mitral valve replacement (MVR). Bj?rk-Shiley (BS), Lillehei-Kaste (LK), and Starr-Edwards (SE) (type 6210) prostheses were implanted at random. All survivors were prospectively followed by regular clinical examinations every 6 to 12 months for 15 years. The mean follow-up time was 14.8 years. A constant subjective improvement after 15 years was reported in 62% of pts with BS, 30% with LK, and 49% with SE. The cumulative 14-year survival rate was 0.62 +/- 0.13 (BS), 0.56 +/- 0.16 (SE), and 0.54 +/- 0.15 (LK), respectively. Late mortality was due to thromboembolic events (n = 3), bleeding complications (n = 3), congestive heart failure (n = 7), documented arrhythmias or sudden death (n = 6). Thrombotic valve thrombosis (1 BS, 1 LK, 2 SE) required reoperations. Linearized cumulative rates after 14 years for thromboembolic complications were 14.2 +/- 3.1 (BS), 15.8 +/- 3.7 (SE), 24.3 +/- 4.2 (LK). The cumulative risk of severe bleeding complications was not different: BS: 35.8, LK: 35.2, SE: 34.3. During the first years of observation no significant differences between these mechanical prostheses could be observed, however, after 14 years of long-term follow-up the cumulative event-free rates were more favorable for the BS prosthesis.     

DeBakey Surgitool mechanical heart valve prosthesis, explanted at 32 years

Contemporary mechanical heart value prostheses are expected to last "just about forever" or the patient's lifeline. They do however still suffer complications, some of which necessitate premature explantation. Complications today are mainly related to patient compliance with anticoagulant medication, infection and hemorrhage. The DeBakey Surgitool mechanical heart valve was the first such device to have Pyrolyte components. We present a DeBakey surgitool mechanical heart valve that was in place for 32 years! It was explanted for dysfunction related to tissue overgrowth and not to its related components. With good patient compliance, this mechanical heart valve prosthesis is an example of good prosthetic valve durability.     

Prevalence of pannus formation after aortic valve replacement: clinical aspects and surgical management

Pannus formation after aortic valve replacement is not common, but obstruction due to chronic pannus is one of the most serious complications of valve replacement. The causes of pannus formation are still unknown and effective preventive methods have not been fully elucidated. We reviewed our clinical experience of all patients who underwent reoperation for prosthetic aortic valve obstruction due to pannus formation between 1973 and 2004. We compared the initial 18-year period of surgery, when the Björk–Shiley tilting-disk valve was used, and the subsequent 13-year period of surgery, when the St. Jude Medical valve was used. Seven of a total of 390 patients (1.8%) required reoperation for prosthetic aortic valve obstruction due to pannus formation. All seven patients were women; four patients underwent resection of the pannus and three patients needed replacement of the valve. The frequency of pannus formation in the early group was 2.4% (6/253), whereas it was 0.73% (1/137) in the late group (P < 0.05). Pannus was localized at the minor orifice of the Björk–Shiley valve in the early group and turbulent transvalvular blood flow was considered to be one of the important factors triggering its growth. We also consider that small bileaflet valves have the possibility of promoting pannus formation and that the implantation of a larger prosthesis can contribute to reducing the occurrence of pannus.     

Use of prothrombin fragment 1+2 for evaluating anticoagulant therapy after mechanical heart valve replacement

Prothrombin fragment 1+2 (F1+2) is a coagulation factor newly used as a molecular marker to monitor anticoagulant therapy in patients undergoing heart valve replacement. We evaluated the usefulness of F1+2 against that of prothrombin time (PT) reported as the internationalized normalized ratio (INR) in 93 patients undergoing mechanical heart valve implantation between August 1999 and July 2000. The study group consisted of 38 men and 55 women, with an average age of 61.1±11.2 years. The surgeries were 34 aortic replacements, 9 double valve replacements, and 50 mitral valve replacements. Warfarin doses were controlled based on PT-INR values at a target range of 1.5–2.5 F1+2 levels in the 0.4–1.2 nmol/l level were considered normal. No thromboembolism or bleeding complication occurred in any patient during the mean follow-up period of 12 months. The overall correction coefficient between F1+2 and PT-INR was 0.165 (P<0.001). A few specimens showed abnormally high levels of F1+2, even when PT-INR values were within the optimal range. The plasma levels of F1+2 that fell within normal range came from specimens with PT-INR values <1.50. The plasma levels of F1+2 that corresponded to PT-INR values of 1.50–2.50 fell just within the normal range, and the F1+2 levels corresponding to PT-INR values >2.50 were less than half of the lower limit of normal. Our analysis involving F1+2 confirmed PT-INR in the 1.5–2.5 range following mechanical heart valve implantation to be optimal. We found that using F1+2 to monitor individual response to anticoagulation therapy is useful when PT-INR values are difficult to obtain.     

Correlation between ventricular flow field and valve closing sound of mechanical mitral prostheses

The Jyros (JR) valve and the newer On-X and MIRA valves, all installed antianatomically, were compared with the St. Jude Medical (SJM) valve in the mitral position to study the effects of valve design differences on the down-stream flow field and the associated valve closing sound. The dynamic particle image velocimetry method utilizing a high-speed video flow visualization technique was used to map the velocity field, and wavelet analysis of the sound was used to find the correlation between the ventricular flow field and the valve closing sound. Based on the experimental data, the following general conclusions can be made. In the velocity field directly below the mitral valve, where the distinct characteristic differences of the valve designs will be evident, twin symmetrical circulations were observed due to the divergent nature of the flow generated by the two inclined half-disks with the valve installed in the anti-anatomical orientation; the SJM, the On-X, and the MIRA valves generated a centrally downward circulation that opposed the valve leaflet closing movement, and resulted in relatively loud valve closing sounds.     

Long-term experience with the Bjork-Shiley Monostrut tilting disc valve

The Bjork-Shiley Monostrut valve is tilting disc mechanical valve prosthesis. This study was designed to present the long-term outcome of our experience. One hundred and thirty-seven Bjork-Shiley Monostrut valves were implanted in 101 consecutive patients from November 1983 to February 1990. There were 60 male and 41 female with mean age of 34.5 yr at the time of operation. Fifty-nine patients underwent single valve replacement, 38 had double valve, and 4 had triple valve replacement. There were six in-hospital deaths (5.9%): three from cardiopulmonary bypass weaning failure and one each from septic shock, sudden cardiac arrest, and uncontrollable bleeding. Mean duration of follow-up was 181.2+/-76.2 months. Overall survival was 86.2% at 15 yr and 83.1% at 20 yr. Patients with mitral valve replacement had 93.5% and 90.2% cumulative survival at 10 and 15 yr, respectively, while patients with aortic valve replacement had 91.1% and 86.5% cumulative survival at 10 and 15 yr. Two groups had no significant difference in survival. Double valve replacement patients had 92.2% and 84.0% survival at 10 and 15 yr, respectively. There were no significant differences in survival between the single and double valve replacement groups. Freedom from thromboembolism was noted in: 97.8%, 97.8%, 96.4% and 87.8% at 5, 10, 15 and 20 yr, respectively. Absence of endocarditis was noted in 98.6% and 94.8% at 15 and 20 yr. Absence of reoperation was 92.5% at 20 yr. In conclusion, the Bjork-Shiley Monostrut valve is reliable, with a similar incidence of valve-related morbidity as in other mechanical valves.