Mitral Valve Replacement with the Hancock Bioprosthesis: Five- to Ten-Year Follow-up

One hundred eleven patients undergoing mitral valve replacement, either alone (56) or in conjunction with another type of prosthetic valve, prior to 1975 were evaluated. Hospital mortality was 9.9%. Cumulative follow-up is 505 patient-years (mean, 5.4 years). Seventy patients have been followed between 5 and 10 years. Late mortality for mitral valve replacement alone is 4.3 ± 1.3% per patient-year; actuarial survival is 82 ± 6% at 5 years and 65 ± 11% at 10 years. The incidence of emboli was 3.3 ± 0.9% per patient-year for all patients with bioprostheses (62) and 4.2 ± 1.7% per patient-year for bioprostheses and concomitant mechanical aortic valves (32). In patients with only bioprostheses, two of twelve emboli occurred within the first 6 postoperative months and there were three fatal cerebral emboli (0.8 + 0.5% per patient-year). The incidence of hemorrhagic complications is 4.9 ± 1.9% for anticoagulated patients with bioprostheses and mechanical aortic valves; one hemorrhage was fatal (0.7 ± 0.7% per patient-year). Intrinsic mitral bioprosthesis failure occurred in 10 patients; 2 died. Five patients had valve failure secondary to perivalvular regurgitation (3) or endocarditis (2). Actuarial late survival free from intrinsic mitral bioprosthetic failure was 99 ± 1% at 5 years, 92 ± 4% at 7 years, 70 ± 12% at 9 years, and 61 ± 13% at 10 years.It is unknown at the present time whether the long-term risk of late intrinsic valve failure and reoperation will outweigh the low incidence of emboli and avoidance of anticoagulant-related hemorrhage. Until further information becomes available, the Hancock bioprosthesis is used for mitral valve replacement only in patients older than 60 years or in patients with contraindications for anticoagulant therapy.     

Heart Valve Replacement with the Hancock Bioprosthesis: A 6-Year Review

All patients who had a mitral or aortic Hancock valve replacement between June, 1974, and June, 1979, were reviewed. A total of 734 bioprostheses were implanted in 632 patients: 291 had mitral (MVR), 239 had aortic (AVR), and 102 had both mitral and aortic valve replacement (MVR + AVR). In 228 patients, an associated surgical procedure was necessary. It involved conservative valve operation in 205 of them. The hospital mortality was 9.6% (28) for MVR (11.5% with associated operation), 4.6% (11) for AVR (8.7% with associated operation), and 13.7% (14) for MVR + AVR (13.0% with associated operation).The follow-up period was between 1 and 6 years with a total follow-up of 934.6, 714.6, and 288.3 patient-years for MVR, AVR, and MVR + AVR, respectively. The late mortality was 0.96% (9), 1.53% (11), and 2.08% (6) per patient-year for MVR, AVR, and MVR + AVR, respectively. The thromboembolic rate was 1.49%, 0.14%, and 2.08% per patient-year for MVR, AVR, and MVR + AVR, respectively. There were twelve valve failures (six were due to rupture; four, thrombosis; one, insufficiency because of intrinsic failure; and one, stenosis without evident cause at reoperation). This represents a failure rate of 0.53%, 0.13%, and 2.08% per patient-year for MVR, AVR, and MVR + AVR, respectively. These results encourage us to continue our routine use of the glutaraldehyde xenografts as the safest valve substitute at present.     

Aortic Valve Replacement with Starr-Edwards Valves over 14 Years

Three hundred thirteen patients underwent aortic valve replacement with 319 Starr-Edwards caged-ball prostheses and have been followed for 1 to 14 years. Hospital mortality (24.8%) and first-year mortality (4.8%) suggest that this is a high-risk group. Overall postoperative patient survival was 37.1%, with 18.8% free from any event, at 14 years. Thromboembolism was the most significant single event (a probability of 18.7% at 14 years), and the Series 2300/2320 valves were associated with a probability of hemolysis of nearly 80% over 13 years.Patients who underwent valve replacement before 1973 had a significantly greater probability of late death (31.1%) and of complications (47.1%) during the first 5 years. Those patients undergoing replacement after 1973 had a significantly greater probability of thromboembolic episodes (15.4%).Starr-Edwards caged-ball prostheses provide an acceptable valve replacement for high-risk patients. However, the overall complication rate of 81.2% over 14 years, compared with 78% for homograft valves for the same period, does not support the adoption of this prosthesis as the valve of first choice at this hospital.     

Clinical Results of Valve Replacement by the Starr-Edwards Prosthesis

Heart valve replacement has initiated special research efforts and has led to debate among surgeons from different surgical services. It is in this area of cardiac surgery that complications are frequent. This paper is a summarized review of the problems related to valve replacement by the Starr-Edwards prosthesis at the University of São Paulo Medical School Heart Institute. It describes the difficulties which led the authors to abandon its use in 1971. Clinical experience is from July 1958 to January 1974.     

Prosthesis-Patient Mismatch Increases Early and Late Mortality in Low Risk Aortic Valve Replacement

PPM was highly associated with long-term all-cause mortality. Small Aortic Valve Annulus MDT (SAVA-MDT) exploring options to prevent PPM, including the implantation of newer generation prosthetic valves, aortic root enlargement and TAVI, should be established.

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Long-term Results in 1375 Patients Undergoing Valve Replacement with the Starr-Edwards Cloth-covered Steel Ball Prosthesis

The two principal considerations with prosthetic valves are durability and thromboembolism. With the widespread interest in recently developed prosthetic valves (porcine, tilting disc, Cooley), the long-term results at one institution with a single prosthesis were considered of particular importance. Accordingly, a 97% follow-up has been completed on 1375 patients (pts) undergoing prosthetic valve replacement with the Starr-Edwards cloth-covered steel ball prosthesis at New York University between October 1967 and December 1975. Operative procedures were as follows: aortic valve replacement (AVR): 470 pts; mitral valve replacement (MVR): 362 pts; combined AVR and MVR: 129 pts; other combined procedures: 414 pts. Overall operative deaths were 13.7%, 9% for AVR, 10.8% for MVR, and 18.6% for combined AVR and MVR. At seven years, AVR survival was 64%, and MVR survival 64.5%. There has been widespread pessimism, usually without significant data, about the cloth-covered prosthesis, because of concern of cloth wear, hemolysis and other complications. Therefore, a particularly significant finding by actuarial analysis was that 85% of surviving patients with isolated AVR remained free of emboli for five years. In pts surviving isolated MVR, 80% remained free of emboli for five years. Of those having embolic episodes, 33% were not on anticoagulants. Fatal hemorrhage from anticoagulants occurred in 0.8% of pts. Endocarditis occurred in 5.7% of the entire group, with 1.3% requiring reoperation. Clinically significant hemolysis occurred in 5.1% of the group, with only 0.2% requiring reoperation. Hence, the total frequency of clinically significant cloth-wear was less than 0.5%. These data indicate both the reliability and the limitations of the Starr-Edwards cloth-covered steel ball valve and can be used in comparing experiences with the more recently developed prostheses.     

Late Results of Triple Valve Replacement: A 14-Year Review

Forty-eight patients have undergone simultaneous triple valve replacement at our institution over the past 14 years. This series was reviewed as a baseline for comparison with more recent tricuspid valve reparative procedures and to assess the natural history of advanced rheumatic heart disease with surgically corrected valvular lesions. Survival was 81% at one month and 32% at 14 years, not significantly different from results with double valve replacement during the same period, and not related to whether the tricuspid involvement was organic or functional. Forty-three percent of the late deaths were clearly valve related, a percentage which would undoubtedly be lowered with currently available prostheses. Functional class was determined in 13 of the 17 current survivors (mean follow-up, 10.3 years), and was improved over preoperative functional class in all but 3 patients. Three patients died of progressive congestive heart failure despite normally functioning prostheses; the reasons for these deaths are open to speculation.     

Active Native Valve Endocarditis: Determinants of Operative Death and Late Mortality

Background. In this report, we reviewed 247 patients who underwent operation by our team for active native valve endocarditis between January 1979 and December 1993.

Methods. There were 201 male and 46 female patients (mean age, 45.4 ± 6 years). The aortic valve was involved in 163 cases, the mitral valve in 36 cases, both mitral and aortic valves in 44 cases, and the tricuspid valve alone in 4 cases. The most common microorganisms were streptococci. Univariate Pearson (χ² test) and multivariate (stepwise logistic regression [BMDPLR]) analyses were used to identify significant predictors of operative mortality, reoperation, and recurrent endocarditis. Cox proportional hazards regression model was used to study late survival.

Results. Operative mortality was 7.6% (n = 19). Increased age, cardiogenic shock at the time of operation, insidious illness, and greater thoracic ratio (>0.5) were the predominant risk factors; the length of antibiotic therapy appeared to have no influence. Two hundred thirteen patients were followed up. Median follow-up time was 6 years (range, 2 to 19 years). Overall survival rate (operative mortality excluded) was 71.3% ± 3.8% at 9 years. Increased age, preoperative neurologic complications, cardiogenic shock at the time of operation, shorter duration of the illness, insidious illness before the operation, and mitral valve endocarditis were the predominant risk factors for late mortality. The probability of freedom from reoperation (operative mortality included) was 73.3% ± 4.2% at 8 years; risk factors were younger age and aortic valve endocarditis. The rate of prosthetic valve endocarditis was 7%. No significant risk factor was found.

Conclusions. Increased age, insidious illness, and hemodynamic failure are the main risk factors for operative mortality. Long-term survival is good except for patients with preoperative neurologic complications and mitral valve endocarditis.     

Late Evaluation of Patients Undergoing Valve Replacement with the Björk-Shiley Prosthesis

This study analyzes 484 patients who survived mitral, aortic, or mitral and aortic valve replacement using the Björk-Shiley prosthesis from January, 1970, through December 31, 1974. Long-term follow-up of 1½ to 6½ years (mean, 3.67 yr) was done on 435 patients (98.2%).Eighty to 85% of the patients have improved noticeably. Thromboembolic problems occurred in 6.9%, representing 1.5 emboli per 1,000 patient-months. Anticoagulant bleeding problems occurred in 6.4% of the patients; late mortality was 15%.Actuarial survival curves showed patients at risk to 6 years having a 79% chance of survival. The same analysis according to preoperative New York Heart Association Functional Classification showed a striking reduction in survival in Class IV patients. The Björk-Shiley prosthesis is a good choice for valve replacement today. Earlier diagnosis and treatment are needed to obtain better long-term survival.     

Bacteremia,Endocarditis, and the Hancock Valve

Among 373 patients with porcine xenografts, there were 27 instances of exposure of the xenograft to bloodstream or endocardial infection in 22 patients. Nine patients underwent 10 separate insertions of xenografts for active infective endocarditis. There were no early infections or valve failures. Three patients returned with a late prosthetic valve endocarditis (PVE) due to a new infection. There were 6 instances of bacteremia early after xenograft valve insertion with no early infection, no valve dysfunction, and 1 instance of late PVE. Eleven patients had PVE on a porcine xenograft. Blood cultures in the 10 patients treated with antibiotics promptly became negative. There were 3 valve-related deaths: 2 from valve incompetence and 1 from mitral and aortic xenograft stenosis. Our experience suggests that the Hancock porcine xenograft is: (1) as resistant to infection as are rigid prostheses in active infective endocarditis; (2) resistant to early postoperative bacteremias; and (3) easier to sterilize than rigid prostheses and more durable than other tissue valves in the face of PVE.     

Early and Late Phase Events Following Bioprosthetic Tricuspid Valve Replacement

From 1961 through 1987, 9,247 patients underwent an intracardiac repair for valvular heart disease. Five hundred thirty patients had a procedure that included a tricuspid valve operation (6%), with tricuspid valve replacement performed in 175 patients (2%), of whom 154 had a bioprosthetic valve implanted (1.7%). These 154 patients with a bioprosthetic valve in the tricuspid position are the subject of this review. There were 27 males and 127 females. Ages ranged from 10 to 75 years. There was tricuspid valve insufficiency in 139 patients (90%), and stenosis plus insufficiency in 15 (10%). Carpentier-Edwards prostheses were implanted in 83 (54%), Ionescu-Shiley in 55 (35%), Hancock in 12 (8%), and Mitroflow in 4 (3%). Concomitant procedures were performed in 146 patients (95%). At least one previous operation had been performed in 86 patients (56%). Preoperatively, 139 patients were in functional Class III or IV (90%). Hospital death occurred in 20 patients (13%). Logistic regression analysis revealed that incremental risk factors for hospital death included increasing peripheral edema preoperatively (p = 0.04), and use of a Hancock prosthesis in the tricuspid position (p = 0.03). All 134 hospital survivors were followed at a mean of 66.01 months, range 1 to 162 months. There were 70 late deaths (52%). Log-rank test indicated that incremental risk factors for late death were: longer cross-clamp time at repair (p = 0.0007); higher pulmonary artery systolic pressure preoperatively (p = 0.01); earlier date of surgery (p = 0.03); and larger tricuspid prosthesis size (p = 0.06).(ABSTRACT TRUNCATED AT 250 WORDS)     

Cardiac Valve Prostheses: Pathological and Bioengineering Considerations

Cardiac valve replacement with mechanical prosthetic or bioprosthetic devices enhances patient survival and quality of life. Nevertheless, prosthesis-associated complications are frequent and contribute significantly to outcome. Thrombo-embolic complications are the most important problems in patients with mechanical valves, necessitating chronic anticoagulation in all patients receiving them. In contrast, patients with bioprosthetic valves, composed of chemically treated animal tissues, generally do not require anticoagulants. However, bioprostheses fail frequently by degeneration, especially that involving cuspal calcification. This paper reviews the pathological and bioengineering considerations in the selection of cardiac prosthetic valves and the management of patients who have received these devices. The significance, morphology, and pathogenesis of the observed major complications and other alterations during function are described in detail. Contemporary investigative trends are summarized, including studies of inhibition of mineralization and other degenerative changes in bioprostheses, improved design rigid mechanical valves with pyrolytic carbon occluders and the development of central-flow, flexible polymeric leaflet valves.