Prosthetic valve endocarditis: Clinicopathologic analysis of 22 necropsy patients with comparison of observations in 74 necropsy patients with active infective endocarditis involving natural left-sided cardiac valves

Clinical and morphologic features are described in 22 necropsy patients with endocarditis involving rigid-framed prosthetic valves: aortic in 15 patients and mitral in 7. The interval from valve replacement to onset of symptoms of prosthetic valve endocarditis was less than 2 months in 8 patients and longer than 2 months in 14 patients. The most frequent infecting organism was the Staphylococcus (13 patients). In each of the 22 patients the infection was located behind the site of attachment of the prosthesis to the valve ring, and the infection spread to adjacent structures in 13 patients, 11 of whom had aortic prostheses. Prosthetic detachment causing severe regurgitation occurred in 12 ot the 15 patients with an infected aortic valve prosthesis, and in 2 of the 7 with an infected mitral valve prosthesis. Prosthetic obstruction by vegetative material occurred in 5 of 7 patients with prosthetic mitral infection and in only 1 of 15 with prosthetic aortic infection. High degrees of conduction defects developed in seven patients with aortic prosthetic valve endocarditis: complete heart block in five, and complete left bundle branch block in two.Comparison of observations in the 22 patients with prosthetic valve endocarditis with those in 74 patients with active infective endocarditis involving natural left-sided cardiac valves revealed significant (P < 0.05) differences in the percent with ring abscess, hemodynamic consequences of the endocarditis (valve stenosis), frequency of Staphylococcus as the causative organism and percent with complete heart block or left bundle branch block. No significant differences were observed between the two groups when comparing age, sex, type of underlying valve disease or frequency of organ infarcts or splenomegaly.     

Cardiac pathology after valve replacement with a tilting disc prosthesis (Björk-Shiley type): A study of 46 necropsy patients and 49 Björk-Shiley prostheses

Clinical and necropsy observations are described in 46 patients who had one or more cardiac valves replaced with a tilting disc prosthesis of the Björk-Shiley type, and these observations are compared with earlier observations in patients with caged ball, caged disc and trileaflet prostheses. In contrast with its frequent occurrence in patients studied earlier with peripheral flow prostheses, either caged ball or caged disc, prosthetic dysfunction from prosthetic disproportion (too small a ventricular cavity or aortic root to freely accommodate the prosthesis) was observed in only 2 of the 46 patients with the semicentral flow Björk-Shiley prosthesis. Significant trauma to erythrocytes, as determined by the presence of renal hemosiderosis, occurred in only 1 of 11 patients who died late after Björk-Shiley valve replacement; it occurred more frequently and with far greater severity in patients who died late after valve replacement with a caged ball or caged disc prosthesis. Prosthetic thrombi may be less frequent after valve replacement with a tilting disc than after replacement with a caged ball or caged disc. They occurred in 7 of 13 patients who died late after Björk-Shiley valve replacement, but 3 of the 7 patients had infective prosthetic endocarditis, and of the remaining 4, only one had been receiving warfarin sodium. In contrast, prosthetic thrombi were observed in 81 and 88 percent, respectively, of 112 patients who died late after valve replacement with a caged ball or caged disc prosthesis, and most of the 112 patients had received anticoagulant therapy. Although the implantation periods were relatively short (3 to 30 months, average 11), prosthetic wear or variance of the tilting disc prosthesis did not occur in any of the 13 patients who died late.

Although the tilting disc (Björk-Shiley) prosthesis is prone to clot (and therefore patients with it require long-term anticoagulation), the device is not intrinsically stenotic or significantly incompetent, it is only minimally traumatic to erythrocytes and, at this time, there is no evidence of prosthetic degeneration or variance.     

Long-term follow-up of aortic or mitral valve replacement. Comparison of results following implantation of a mechanical or biological artificial valve

The prognosis of valvular heart disease is favorably influenced by surgical treatment in spite of the possible incurrence of early or late postoperative complications. The hemodynamic properties of currently implanted bioprostheses and mechanical prostheses are essentially similar. It can be assumed that the fate of the patient, after having survived the early-postoperative phase, is predominantly dependent on the underlying disease and on complications of the prosthetic valve, itself, or the inherent necessity for chronic anticoagulation. To characterize the longterm course more closely, in this study in patients with prosthetic aortic or mitral valves, analysis of the survival rate as well as incidence of valvular dysfunction, late endocarditis, thromboembolism and bleeding associated with anticoagulant therapy was performed separately for patients with Bj?rk-Shiley prostheses and for those with bioprostheses. The study encompasses 407 patients after isolated aortic valve replacement, 226 with Bj?rk-Shiley prosthesis and 181 with bioprosthesis, as well as 269 patients after isolated mitral valve replacement, 142 with Bj?rk-Shiley prosthesis and 127 with bioprosthesis (Table 2). All patients had valve replacement between 1975 and 1983 which was performed in the Department of Cardiovascular Surgery at the German Heart Center in Munich under comparable conditions, since 1977 with employment of cardioplegia. The preoperative characteristics of the groups compared did not differ significantly from each other (Table 1). Continuous follow-up was obtained in 95% of the patients. The mean observation period of all four compared patient groups ranged between 52.1 and 61.3 months. The term "major complication" was used to designate late-postoperative death, hemodynamic derangement due to prosthetic dysfunction, late endocarditis as well as major thromboembolism or bleeding. Prosthetic dysfunction in the case of Bj?rk-Shiley valves was designated as mechanical or due to thrombosis, in the case of bioprostheses as valve degeneration or thrombosis. Late endocarditis was diagnosed only on documentation of - with a minimum interval of 30 days between valve implantation and onset of symptoms - changes in auscultatory findings and a morphological substrate on the implanted valve. Thromboembolism was assumed, after ruling out bleeding, only if a definitive or highly-probable transient or permanent neurologic deficit or a well-established suspicion of acute ischemia in an extremity or visceral organ was present. A bleeding complication was considered as such only if treatment by a physician was required.(ABSTRACT TRUNCATED AT 400 WORDS)     

Calcification of prosthetic valve anuli: A late complication of cardiac valve replacement

A previously undescribed late complication of cardiac valve replacement is calcification at the site of attachment of prostheses. Of 24 patients in whom purely incompetent, non-calcified mitral or aortic valves were replaced with rigid-framed prostheses 3 to 116 months earlier, nine (seven mitral, two aortic) of 26 valves had prosthetic anular calcific deposits. Of the eight prostheses in place for 70 months or longer all contained anular calcific deposits; only one of the 18 valves in place for less than 70 months had periprosthetic calcific deposits. The extent of prosthetic calcium also increased with time. The mechanism of formation of prosthetic anular calcium is uncertain, but accelerated wear of the tissues beneath the prostheses due to the constant to-and-fro motion of the rigid frames may be a factor. Possible complications of prosthetic anular calcific deposits include suture rupture, peribasilar leak, and increased hazard to reoperation.     

Early and late survival following replacement of prosthetic heart valves

From May 1975 to December 1988, 62 patients underwent 66 replacements of prosthetic heart valves, due to structural valve failure in 37, prosthetic valve endocarditis (PVE) in 17, periprosthetic leak in 5, thrombosed valve in 3, hemolysis in 2, and prophylactic removal in 2. Before reoperation, 3 patients were in NYHA Class I, 24 in Class II, 21 in Class III, and 18 in Class IV. Replacements of valve prostheses were at the mitral position in 33 patients, at the aortic position in 16, at the aortic and mitral position in 9, at the mitral and tricuspid position in 5, at the tricuspid position in 2, and at the pulmonary position in 1. There were 6 early deaths (9.1%), and 13 late deaths (7.2 +/- 0.4%/patient-year). Clinical improvement of the current survivors was good. The follow-up duration was 4 months to 11.4 years (mean 3.5 years), and the cumulative follow-up was 180 patient-years (100% complete). Patients undergoing replacement of 2 prostheses showed a higher early mortality rate (35.7%) than those who received replacement of 1 prosthesis (1.9%) (p less than 0.01). The actuarial survival including early deaths was compared using the generalized Wilcoxon test. Survival was better in patients with replacement of one prosthesis than in those with replacement of 2 prostheses (p less than 0.001), and was better in NYHA Class I to III patients than in Class IV patients (p less than 0.05). Replacement of 1 prosthesis for patients with primary tissue failure of bioprostheses showed no operative mortality and a good 5 year survival rate (96 +/- 4%). High risk factors for replacement of prosthetic valves included double valve replacement, NYHA Class IV and PVE.     

Valve dysfunction of the cloth-covered Starr-Edwards ball valve.

BACKGROUND: Between June 1968 and March 1977, Starr-Edwards cloth-covered ball valves were used for valve replacement on a routine basis. METHODS AND RESULTS: Among the 66 operative survivors who underwent an isolated aortic or mitral valve replacement, 20 patients required reoperation 22 times because of valve dysfunction, thromboembolic complication, paravalvular leakage, hemolytic anemia, and/or prosthetic valve endocarditis. Reoperation was performed at a mean of 15.9+/-9.8 years after initial replacement. Excised valves were examined and reoperation after initial operation was reviewed. Operative mortality was 10.0%. Freedom from reoperation for aortic valve replacement and mitral valve replacement was 56.2% at 34 years and 61.0% at 37 years after initial operation, respectively. Cloth wear or pannus formation were observed in all excised prostheses. Orifice cloth was more markedly worn in mitral valves than in aortic valves, particularly in mitral valves of more than 20 years old. Pannus overgrowth contributed to valve regurgitation in the older valves. CONCLUSIONS: Early diagnosis of valve dysfunction and reoperation are recommended as soon as symptoms appear.     

A 12-year clinical experience of cardiac valve replacement with domestic tilting disc valve prostheses in 1013 cases]

1013 patients with cardiac valve replacement during a 12-year period from 1978 to 1990 were reported. 566 cases were implanted with Shanghai-made tilting disc valve prostheses and 447 with Lanzhou-made (C-L valves). Mitral valve replacement (MVR) in 753 patients, aortic valve replacement (AVR) in 102 and double valves replacement (DVR) in 158. The overall early mortality rate was 6.2% with 4.9%, 7.8% and 11.3% after MVR, AVR and DVR respectively. Follow-up study was made in 3097.43 patient-year (mean 3.26 years). The late death rate was 1.6% patient-years and with 1.4, 1.8 and 3.2 after MVR, AVR and DVR respectively. The incidence of late valve-related complication (% patient-years) were: thromboembolism 0.39, anticoagulant-related hemorrhages 0.77, prostheses failure 0.22, prosthetic valve endocarditis 0.38, periprosthetic leak 0.12, and reoperations 0.38. The domestic tilting disc valve prostheses are considered to be qualified valves with low mortality and satisfactory results.     

Ball valve prostheses: Current appraisal of late results

Advanced actuarial techniques are used to analyze late results in 912 patients who had isolated mitral or aortic valve replacement with ball valve prostheses from 1965 to 1974. Experience with noncloth-covered and cloth-covered valves is compared in terms of late survival, rate of thromboembolic complications and reoperation and the influence of anticoagulation. The cloth-covered prostheses have substantially reduced the incidence of emboli after mitral valve replacement (1.9 vs. 6 emboli per 100 patient years) and have thus far eliminated emboli after aortic valve replacement in patients receiving warfarin. Patients with a cloth-covered aortic valve who did not receive warfarin had nine emboli per 100 patient years. The safety of cloth-covered valves is clearly enhanced by warfarin therapy; the efficacy of antiplatelet drugs is still uncertain. Strut cloth wear was found at reoperation in 10 patients. This should be prevented in the new model 2400 composite strut (“track”) valve by a narrow metal track on the inner surface of each strut.

The substantial recent reductions in operative mortality and in prosthesis-related complications pose important questions regarding timing of operations and selection of prostheses. These decisions must be individualized for each patient on the basis of a thorough analysis of late results using modern statistical methods.     

Late prosthetic valve endocarditis. Immediate and long-term prognosis.

From 1975 to 1989, 307 consecutive episodes of infective endocarditis were diagnosed in our hospital. Of those, 35 were cases of late prosthetic valve endocarditis, defined as those occurring after 12 months of valvular replacement. Blood cultures grew streptococci in 15 patients (43 percent), staphylococci in seven (20 percent), enterococci in five (14 percent), Gram-negative bacilli of HACEK group in four (11.5 percent), and Candida in one. Blood cultures were negative in three cases (prosthetic infection was confirmed at surgery). Heart failure due to prosthetic dysfunction occurred in seven patients (20 percent) and emboli in 12 (34 percent). Early valvular replacement was performed in six patients (17 percent). Complications and mortality were dependent on the infective agent. Overall mortality was 23 percent, no death occurred from streptococcal infection, whereas mortality with endocarditis by organisms of the HACEK group and Staphylococcus was 50 percent and 43 percent, respectively. During a mean follow-up of five years, 11 patients (those with prosthetic leaks diagnosed during the active infection and patients with biologic prostheses) required surgery. There was one relapse in a patient with staphylococcal endocarditis and one recurrence, six years after the initial episode. We conclude that immediate prognosis of late prosthetic valve endocarditis depends on the infective agent. Although the immediate prognosis of streptococcal infections is good, the need for early reoperation during follow-up due to progressive perivalvular leak is high. Also, it appears that deterioration of bioprostheses proceeds swiftly after the cure of infection.     

Current developments in the tissue engineering of autologous heart valves: moving towards clinical use

The use of tissue-engineering methods to create autologous heart valve constructs has the potential to overcome the fundamental drawbacks of more traditional valve prostheses. Traditional mechanical valves, while durable, increase the risk for endocarditis and thrombogenesis, and require the recipient to continue lifelong anticoagulant therapy. Homograft or xenograft heart valve prostheses are associated with immune reaction and progressive deterioration with limited durability. Most importantly, neither option is capable of growth and remodeling in vivo and both options place the patient at risk for valve-related complications and reoperation. These shortcomings have prompted the application of tissue-engineering techniques to create fully autologous heart valve replacements. Future clinically efficacious tissue-engineered autologous valves should be nonthrombogenic, biocompatible, capable of growth and remodeling in vivo, implantable with current surgical techniques, hemodynamically perfect, durable for the patient's life and most importantly, significantly improve quality of life for the patient. In order to meet these expectations, the nature of the ideal biochemical milieu for conditioning an autologous heart valve will need to be elucidated. In addition, standardized criteria by which to quantitatively evaluate a tissue-engineered heart valve, as well as noninvasive analytical techniques for use in long-term animal models, will be required. This article highlights the advances, challenges and future clinical prospects in the field of tissue engineering of autologous heart valves, focusing on progress made by studies that have investigated a fully autologous, tissue-engineered pulmonary valve replacement in vivo.     

Echocardiographic and clinical correlations in infectious endocarditis of the left heart

The echocardiographic features were correlated with the clinical findings and outcome in 35 patients with aortic and/or mitral valve endocarditis. There were 26 males and 9 females with a mean age of 38 years. The infection involved native valves in 27 patients and prosthetic valves in 8 patients. Echocardiographically, fourteen patients had involvement of native aortic valve. All patients in this group required surgical intervention, nine patients during antimicrobial therapy. Congestive heart failure was the clinical indication for valvular replacement. A patient died immediately after surgery from low cardiac output syndrome. Six patients had echocardiographic evidence of aortic and mitral valves involvement. A patient in this group expired before surgery, five underwent surgery because of progressive heart failure (aortic or aortic and mitral valves replacement). Seven patients showed lesions on native mitral valve (6 in this group had prolapse syndrome). A patient died from cerebrovascular embolus, two underwent surgery because of persistent infection and embolic events, four were successfully treated with medical therapy. Among patients with prosthetic valve endocarditis, four showed signs of valvular dehiscence and required surgical intervention, during antimicrobial therapy, from congestive heart failure; one patient expired from recurrent infection. The pathological findings correlated well with echocardiographic findings. Conclusions: in IE the localization of lesions by echo has prognostic significance: most patients with aortic valve or aortic and mitral valves endocarditis require early surgical intervention because of congestive heart failure. On the contrary, mitral valve involvement carries a better prognosis, requiring less frequently valvular replacement; the patients with echocardiographic signs of prosthetic valve dehiscence require urgent intervention.(ABSTRACT TRUNCATED AT 250 WORDS)     

An audit of pregnant women with prosthetic heart valves at a tertiary hospital in South Africa: a five-year experience

Background: Cardiac disease in pregnancy is a common problem in under-resourced countries and a significant cause of maternal morbidity and mortality. A large proportion of patients with cardiac disease have prosthetic mechanical heart valve replacements, warranting prophylactic anticoagulation. Aim: To evaluate obstetric outcomes in women with prosthetic heart valves in an under-resourced country. Methods: A retrospective chart review was performed of 61 pregnant patients with prosthetic valve prostheses referred to our tertiary hospital over a five-year period. Results: Sixty-one (6%) of 1 021 pregnant women with A diagnosis of cardiac disease had prosthetic heart valves. Fifty-nine had mechanical valves and were on prophylactic anticoagulation therapy, three had stopped their medication prior to pregnancy and two had bioprosthetic valves. There were forty-one (67%) live births, two (3%) early neonatal deaths, 12 (20%) miscarriages and six (10%) stillbirths. Maternal complications included mitral valve thrombosis (n = 4), atrial fibrillation (n = 8), infective endocarditis (n = 6), caesarean section wound haematomas (n = 7), broad ligament haematoma (n = 1) and warfarin embryopathy (n = 4). Haemorrhagic complications occurred in five patients and all five required blood transfusions. Conclusion: Prophylactic anticoagulation with warfarin in patients with mechanical heart valve prostheses was associated with high rates of maternal and neonatal complications, including significant foetal wastage in the first and early second trimesters of pregnancy. Health professionals providing care for pregnant women with prosthetic heart valves must consistently advise on family planning matters, adherence to anticoagulation regimes and consider the use of prophylactic anticoagulant regimens other than warfarin, particularly during the first trimester of pregnancy.     

Prosthetic valve endocarditis: an overview

Infection of an intracardiac prosthesis, the incidence of which is about 2.5% among patients having undergone valve replacement, is a serious complication with considerable morbidity and mortality. Early prosthetic valve endocarditis (PVE), with an onset within 60 days of valve replacement, accounts for approximately one-third of all cases, while the remaining two-thirds, occur more than two months postoperatively (late prosthetic valve endocarditis). Prosthetic valve endocarditis is most commonly caused by Staphylococcus epidermidis, less frequently by viridans streptococci, Staphylococcus aureus, and gram-negative bacilli. The most likely pathogenetic mechanisms in prosthetic valve endocarditis are intraoperative contamination and postoperative infections at extracardiac sites. Prominent clinical features include fever, new or changing heart murmurs, leukocytosis, anemia and hematuria. The etiologic microorganism can be isolated in more than 90% of all cases. Patients with proven prosthetic valve endocarditis should be examined daily to detect signs of congestive heart failure and changes in murmurs; electrocardiographic monitoring is essential for documentation of arrhythmias. With limitations, echocardiography, especially two-dimensional, may help to demonstrate vegetations or valvular dehiscence. Cinefluoroscopy may reveal loosening or dehiscence of the sewing ring or impaired motion of a radio-opaque poppet due to thrombus or vegetation. Cardiac catheterization, not always necessary even when surgical intervention is anticipated, may provide valuable information on the degree of dysfunction, multiple valve involvement, left ventricular function and extent of concomitant coronary artery disease. In patients with mechanical valves, prosthetic valve endocarditis may be associated with a high incidence of valve ring and myocardial abscesses; the reported frequency of valve ring abscesses is lower with porcine heterografts. Infections on mechanical valves characteristically localize to the sewing ring with subsequent detachment of the prosthesis and valvular incompetence; infections on porcine heterografts tend to localize to the cusps, leading to valvular incompetence because of leaflet destruction. Large vegetations may result in functional stenosis. Over the last ten years the overall mortality of prosthetic valve endocarditis was 53.8%; 73.6% in early and 43% in late prosthetic valve endocarditis. More recently, however, the survival rate appears to be improving. In general, the mortality associated with prosthetic valve endocarditis caused by fungi and Staphylococcus aureus is highest and that of streptococci lowest.(ABSTRACT TRUNCATED AT 400 WORDS)     

Pathologic anatomy of cardiac valve replacement: A study of 224 necropsy patients

Necropsy observations are described in 224 patients who died from 1963 through October 1972 after replacement of one or more cardiac valves by prostheses: 128 patients died within 2 mo of operation, and 96 patients at later periods up to 116 mo. Of the 281 valves replaced, Starr-Edwards prostheses were used in 250. Prosthetic dysfunction continues to be the most common cause of death (approximately 30%) in patients dying either early or late after valve replacement. It is hoped that the metal balls and cloth-covered struts will decrease the late frequency of prosthetic dysfunction, but not enough time has elapsed for this altered prosthesis to be tested adequately. Present data indicate that the frequency of clinical embolism and prosthetic thrombosis after use of the clothcovered prostheses is less than that observed in the noncloth-covered prostheses. Cloth wear with possible dislodgement and increased intravascular hemolysis, however, remains of concern. The frequencies of peribasilar fistulae, infection at sites of attachment of prostheses, and aneurysm formation at sites of excision of left ventricular papillary muscles are decreasing. It appears that secondary left ventricular endocardial fibroelastosis after mitral replacement, aortic root and coronary ostial intimal proliferation after aortic valve replacement and calcification of valve anuli will only increase with time after valve replacement. The latter changes may prove to be major long-term problems.

It is clear after a decade of cardiac valve replacement that the ideal valve prosthesis is not yet available, or if available, not adequately tested. Thus, valve replacement at this time must be reserved for the patient severely disabled by cardiac valve disease.     

Reoperations for malfunction of heart valve prostheses, especially with endocarditis

Following the increasing number of patients with heart valve replacement and an extended indication (older age groups, acute infective endocarditis, multivalvular procedures) the indicence of malfunction of valve prostheses is continuously growing. The prognosis of patients with a malfunctioning prosthesis mainly depends on early diagnosis and adequate therapy. In a retrospective study (1970 to 1984) 3,533 implanted heart valve prostheses were followed up and the cases with malfunction (n = 150; 4.2%) were analyzed. During the follow-up period after 1963 mitral valve replacements (MVR) there were 78 cases of malfunction (4.6%), after 1806 aortic valve replacements (AVR) 73 (4.1%), and after 34 tricuspid valve replacements (TVR) 4 malfunctions (11.8%). These malfunctions concerned periprosthetic leakages (n = 65), prosthetic endocarditis (n = 42), prosthetic valve thrombosis (n = 13), mechanical dysfunction including bioprosthetic degeneration (n = 17), valve related hemolysis (n = 3), and unsatisfactory hemodynamics (n = 10). Special attention was turned to the problem of prosthetic endocarditis (1963-1984) found in a total of 71 patients following 3,878 prosthetic valve replacements (1.9%). In 42 reoperated cases (1970-1984) the causing microorganisms were analyzed, demonstrating staphylococci in a leading position. Secondary complications and additional risk factors are discussed. There has been no change concerning the basis and the strategy of management for prosthetic endocarditis for many years: After a short time of conservative management with tested antibiotics, early reoperation and exchange of the prosthesis seems to be the optimal therapy, despite a distinctly high postoperative mortality (17%).(ABSTRACT TRUNCATED AT 250 WORDS)     

Reoperations on heart valve prostheses. Apropos of 58 cases

In the period from 1968 to November 1980, 1 023 patients underwent surgery for single or multiple valve replacement. Fifty three patients (6,6% of the follow-up population) had to be reoperated, including 5 patients who had to be reoperated twice, giving a total of 58 reoperations. The average interval before reoperation was 30 months. The incidence was similar in monovalvular (7,5 p. 100 mitral valves, 5 p. 100 aortic valves) and polyvalvular (7 p. 100) cases. On the other hand, the incidence of reoperation of tricuspid prostheses (17 p. 100) was significantly superior to that of mitral valve (5,3 p. 100) or aortic valve (3,8 p. 100) prostheses. In 91 p. 100 of cases, the indication for reoperation was prosthetic valve dysfunction related to endocarditis in over a third of cases (21). In 32 cases, reoperation was required in the absence of any infectious process: 13 spontaneous perivalvular leaks, 10 thromboses, and 9 stenosing prostheses. There were no reoperations for wear of the prosthetic material. Only 9 p. 100 of patients were reoperated for uncorrected valvular disease. The prognosis of these reoperations was poor; hospital mortality being 42,5 p. 100. This high mortality rate is explained by the frequency of reoperation for infective endocarditis (36 p. 100) in our series, the mortality of which was 73,6 p. 100 and even higher when reoperation was an emergency for infectious or hemodynamic reasons. There was also a high mortality rate with reoperation for thrombosis (30 p. 100) because of the severe myocardial dysfunction in thrombosis of tricuspid prostheses and the emergency situation associated with mitral prosthetic valve thrombosis. Excluding these two complications, the average mortality was 21 p. 100. Although the surgical indications are relatively easy for thrombosis, perivalvular leak and stenosing prostheses, they are particularly difficult in infectious endocarditis especially with regards to the timing of reoperation. We believe that, ideally, reoperation should be delayed as long as possible to allow the antibiotic therapy the maximum time to take effect. Surgery can then be performed after controlling the infection and before the installation of severe hemodynamic distress.     

Late prosthetic valve endocarditis: review of 19 cases and treatment

Eighteen out of 1606 patients treated by valve replacement betweenJanuary 1971 to June 1979 were admitted in Brugmann UniversityHospital for late prosthetic valve endocarditis. Of the 19 episodes(one patient had two distinct episodes four years apart), nine(group I) were treated medically and 10 (group II) by combinedmedical and surgical therapy. The infective organism was Staphylococcusepidermidis in two-thirds of our cases. Two cases in group I(22.2%) were long-term survivors. In group II, all 10 patientssurvived reoperation. There were four late deaths; six patients(60%) were still alive 1.8 to 4.4 years later (mean survivalthree years). Prompt prosthetic valve replacement is recommended in the presenceof systemic emboli, evolving murmurs, uncontrolled sepsis orcongestive heart failure (especially if the infective organismis a fungus or a staphylococcus), in late prosthetic valve endocarditis.     

Aortic valve replacement with 31- and 33-mm mechanical prostheses: early results

The mean aortic diameter of Indian adults is 25-31 mm, yet fewer than 1% of worldwide heart valve procedures involve a 31-mm aortic heart valve. Of the 72 large prosthetic aortic valves (31-mm) implanted in the Asia Pacific region during 2001-2003, 53 (74%) were implanted at our institution. This retrospective study was undertaken to assess early results and outcomes, on echocardiography and exercise testing, in patients who received large prosthetic aortic valves. From January 1997 through December 2002, 27 patients underwent isolated aortic valve replacement with 31-mm St. Jude Medical prostheses, and 4 patients underwent aortic valve replacement with 33-mm St. Jude Medical reversed mitral prostheses. These 31 patients were among 240 who underwent isolated aortic valve replacement at our institution during the same period. The preoperative, perioperative, and postoperative data were collected from case records and patient follow-up. Fifteen of the 31 patients underwent echocardiography and exercise testing at least 6 months after operation. There were no early deaths. No patient developed prosthetic valve endocarditis or paravalvular leak. One patient, who developed valve thrombosis as a result of noncompliance with the anticoagulation regimen, underwent thrombectomy and died during the early postoperative period, due to low cardiac output. There was no structural failure or anticoagulant-related hemorrhage. Postoperatively, the peak and mean gradients across the prostheses were low. The exercise performance of all the patients was good. These early favorable results need to be borne out by longer and more comprehensive study of larger groups.     

Early results with composite strut caged ball prostheses

The Starr-Edwards model 6400/10 mitral and 2400/10 aortic valve prostheses incorporate metallic tracks on the inner aspects of clothcovered struts in an attempt to preserve the favorable thromboembolic performance of cloth-covered valves while avoiding the risk of cloth wear. Two hundred seventy operative survivors of mitral valve replacement with the model 6400/10 prosthesis, all on continuous anticoagulant therapy, have been followed up for a mean period of 2.3 (maximal 6) years. The late survival rate is 91 percent and the removal-free rate is 94 percent at 5 years. The rate of embolism (mean ± standard error of the mean) is 4.6 ± 0.9 percent per patient-year. Significant bleeding complications occurred at a rate of 1.0 ± 0.2 percent per patient-year; there were no deaths.Two hundred forty operative survivors of aortic valve replacement with a model 2400/10 prosthesis, all on continuous anticoagulant therapy, have been followed up for a mean of 2.0 (maximal 7) years. The 5 year survival rate is 84 percent and the removal-free rate is 98 percent. Embolism occurred at a rate of 3.3 ± 0.8 percent per patient-year. Hemorrhagic complications occurred at a rate of 2.1 ± 0.6 percent per patient-year; there were three fatalities.Cloth wear and hemolysis have not been significant problems with this prosthesis, and the rates of thromboembolism are comparable with those reported for xenograft bioprostheses. The composite strut (track) valve prosthesis is a durable alternative to tissue valves in patients who are able to tolerate anticoagulant therapy.     

Late endocarditis-associated obstructive dysfunction of a tricuspid ball-cage-type valve. Doppler echocardiographic findings and therapeutic implications

Thrombotic obstruction is rare in bacterial endocarditis involving prosthetic heart valves. A 45-year-old man who had three intracardiac, ball-cage-type prosthetic valves, presented with streptococcal septicemia. Major obstruction of the tricuspid Smeloff-Cutter valve and normal function of the two other prostheses were documented by Doppler echocardiography. Emergency replacement of the tricuspid valve alone was decided on the one basis of this echocardiographic diagnosis, and successfully performed. Operative findings confirmed the noninvasive findings.