Homograft replacement of the mitral valve: eight-year results

OBJECTIVE: The objective of this study was to assess whether the mitral homograft represents a valuable alternative for complete or partial mitral valve replacement. METHODS: Since 1993, 104 patients underwent mitral homograft replacement surgery. The mean age was 38 +/- 15 years. The causes of mitral valve disease were rheumatic disease (n = 76), infective endocarditis (n = 24), and others (n = 4). Sixty-five of these procedures were total homografts, and 39 were partial homografts. RESULTS: The mean follow-up was 52 +/- 35 months (maximum, 117 months). Overall hospital mortality was 4 (3.8%) of 104 patients and 2.5% versus 8.7% for patients without endocarditis and with endocarditis, respectively (P <.19). There were 9 late deaths (cardiac, 4; noncardiac, 5). There have been 5 early (<3 months) and 10 late reoperations. Of the remaining 77 patients, New York Heart Association class was I in 61, II in 14, and III in 2. Four patients had endocarditis, and 5 had an ischemic or hemorrhagic event. Freedom from major cardiac events was 71% +/- 6% at 8 years (partial at 81% vs total at 63%, P <.19). Among patients with a total homograft, freedom from major cardiac events was 61% +/- 9% and 85% +/- 8% at 6 years in patients younger than and older than 40 years, respectively (P =.09). CONCLUSION: The risk of early dysfunction related to a mismatch between the mitral homograft and the patient's valve is the main pitfall of the technique. Beyond that stage, the results were comparable with those of bioprostheses in a cohort of young patients.     

Homograft replacement of the mitral valve in young recipients: mid-term results.

OBJECTIVE: Mitral homograft (MH) can represent an interesting alternative for valve replacement in the young. However, concerns have been expressed about the durability of valve allografts in children. We report our experience with MH replacement in young patients. METHODS: From 1993 to 1997, 13 young patients aged 3-25 years (mean 15+/-6 years) underwent total mitral valve (MV) replacement with a cryopreserved homograft (CH). All but one had previously undergone one or more cardiac operations. The indications were rheumatic disease (6), acute and subacute endocarditis (2), congenital heart disease (4), and systemic lupus endocarditis (1). RESULTS: No in hospital deaths are reported. Discharge echocardiogram showed a well-functioning MH in all but one patient. One patient was lost to follow-up. Follow-up ranged from 0.7 to 6.6 years (4.1+/-2.2). On follow-up two patients were doing well. Two patients died without reoperation and both had MV stenosis. Seven patients (54%) required reoperation: mean delay 4.17 years (0.7-7). In all cases, thickening, shrinking and calcification of the allograft were present. None of these seven had contributive histopathologic changes. One patient presenting recurrent MV insufficiency will require a reoperation. CONCLUSION: MV homograft is a safe and reproducible technique, but does not provide durable results and should not be used in young patients.     

Homograft aortic valve replacement: seven years' experience with antibiotic-treated valves.

One hundred and sixty-five patients had their aortic valve replaced with antibiotic-sterilised homograft. In all cases, a two-layered freehand technique of valve implantation was used. Tailoring (narrowing) of the annulus was required in 29 cases, and an aortic root gusset was used to enlarge the non-coronary sinus in 68 cases. There was an early mortality of 1.8% and late mortality of 2.4%. The actuarial survival rate was 95% at a maximum follow-up of seven years. The incidence of valvar regurgitation (early diastolic murmur) was 11.5% up to six months after operation and an additional 7.2% subsequent to this. Overall, it was trivial in 10.3%, mild in 7.8%, and moderate in 0.6%. Most valve regurgitation was non-progressive and actuarial analysis showed 74% regurgitation-free valves at the end of seven years. The age of the donor and the valve storage time showed some relationship to valve deterioration. Special attention has been paid to the control of hypertension to prevent accelerated graft degeneration. The results suggest that this has been successful. Anticoagulant therapy was not used and thromboembolism has not been seen in patients undergoing isolated aortic valve replacement. There was one case of miliary tuberculosis after homograft valve replacement but no pyogenic or fungal endocarditis occurred. No haemolysis, calcification, or valvar stenosis were observed. This series, followed for a maximum of seven years, shows excellent sustained valve performance and a very low incidence of important postoperative regurgitation, with 91.8% of the survivors symptom-free.     

Late results after mitral valve replacement

Recent reports on mitral valve replacement (MVR) are reviewed and topics in this field are discussed. In addition to the widely used St. Jude Medical (SJM) valve, five other bileaflet prosthetic valves are now commercially available in Japan. The clinical performance of the new type of bileaflet valve appears similar to that of the SJM valve. The lincarized rate of thromboembolism occurrence for any bileaflet valve is less than a few %/patient-year in most reports. The actuarial and actual freedom from structural valve deterioration(SVD) 14 years after MVR with the Carpentier-Edwards pericardial valve was reported to be 69% and 83%, respectively, while the actuarial freedom from SVD 12 years after MVR with the Hancock II porcine valve was 82%. In Japan, the rate of use of bioprostheses is approximately 10%. When selecting a prosthetic valve, informed patient consent based on the most recent data is recommended. Numerous reports have been published on chorda-preserving MVR indicating the superiority of this technique over conventional MVR in terms of left ventricular function. There are several options for prescribing the chordae and for artificial chordae reconstruction. Improved methods for sparing the chordae are being investigated in animal models.     

A comparison of mitral valve reconstruction with mitral valve replacement: intermediate-term results

The continued good results after mitral valve reconstruction prompted this retrospective study to compare operative and late results from our institutional experience since 1976 with 975 porcine mitral valve replacements (MVRs) (1976 to December 1987), 169 mechanical MVRs (1976 to December 1987), and 280 Carpentier-type mitral valve reconstructions (CVRs) (1980 to mid-1988). The operative mortality was 2.0% for isolated CVR, 6.6% for isolated mechanical MVR, and 8.5% for isolated porcine MVR. The overall operative mortality was 5.0% for CVR, 16.6% for mechanical MVR, and 10.6% for porcine MVR. The overall 5-year survival including hospital deaths was 76% for CVR, 72% for mechanical MVR, and 69% for porcine MVR. By multivariate analysis, the predictors of increased operative risk and of decreased survival were age, New York Heart Association functional class IV status, previous cardiac operation, and performance of concomitant cardiac surgical procedures. The type of valvular procedure was not predictive of operative risk or overall survival. The 5-year freedom from reoperation was 94.4% for nonrheumatic patients having CVR, 77.4% for rheumatic patients having CVR, 96.4% for mechanical MVR, and 96.6% for porcine MVR (p less than 0.05, rheumatic patients with CVR versus both MVR groups). The 5-year freedom from all valve-related morbidity and mortality was significantly better for valve reconstruction compared with both types of valve replacement. Thus, the operative risk and late survival obtained after mitral valve reconstruction were at least equivalent to those obtained after MVR. In addition, patients receiving mitral valve reconstruction had less valve-related combined morbidity than patients receiving valve replacement, thus making mitral valve reconstruction preferable in some patients with mitral insufficiency.     

The results of valve replacement for mitral valve prolapse

Between January, 1975, and December, 1982, 33 patients underwent mitral valve replacement for mitral valve prolapse secondary to myxomatous degeneration. The majority were in the seventh decade of life (median age, 62 years), and all were seen with symptoms of mitral regurgitation. Echocardiography was more accurate in making the diagnosis of mitral valve prolapse more often (75%) than angiography (66%). Thirty-eight percent of the patients who underwent cineangiography had concomitant coronary artery disease and had coronary artery bypass grafting as well as mitral valve replacement. There was 1 operative death, an operative mortality of 3%. There were 6 late deaths, a late mortality of 18%. Of the 26 long-term survivors, 23 (88%) were in New York Heart Association Functional Class I and 3 (12%) were in Class II. The average length of follow-up was 33.25 months, and the 5-year actuarial survival was 76%. There was only one incident of thromboembolism (3%). Short-term and long-term survival were not related to the severity of mitral regurgitation but to the status of the left ventricle and the overall condition of the patient. These data suggest that older patients with severe mitral regurgitation secondary to mitral valve prolapse can undergo valve replacement with low operative mortality and gratifying long-term results.     

Early results of mitral valve replacement.

Early results of mitral valve replacement were reviewed in 336 unselected patients, 261 without and 75 with concomitant coronary artery bypass grafting (MVR and MVR + CABG groups). Early (less than 30 days) mortality was 7% in the MVR and 16% in the MVR + CABG group, with cardiac failure as the dominant cause. In multivariate analysis, the variables most strongly related to early mortality were congestive heart failure, diabetes and previous cardiac surgery in the MVR group and congestive heart failure in MVR + CABG. In the cases with fatal outcome the incidence of peroperative technical complications was 32% at MVR and 17% at MVR + CABG. The incidence of myocardial injury was 21% and 35% in the respective groups, and the early mortality in these cases was 19% vs 23%. Half of all fatal cases showed signs of peroperative myocardial injury. Multivariate analysis showed factors independently related to myocardial injury to be year of surgery and aortic cross-clamp time in MVR and previous cardiac surgery in MVR + CABG. Operation before cardiac reserves are reduced, optimal peroperative myocardial preservation and avoidance of technical errors should improve results of MVR.     

Patient status five or more years after mitral valve replacement

Among 136 consecutive patients undergoing isolated mitral valve replacement prior to February, 1966, 30 died postoperatively and 33 died during the follow-up period that extended to nine years. The late deaths were due to cardiac causes in 13 patients, thromboembolism in 9, and miscellaneous causes in 8 and were sudden (cause undetermined) in 3. Of patients surviving five or more years after mitral valve replacement, 55% remained improved (40.4% of the entire group).     

Long-term results of bioprosthetic mitral valve replacement: the pericardial perspective

Pericardial valve bioprostheses were introduced in early 1970s and were widely used in the 1980s. The longterm results with the Ionescu-Shiley valve, the first commercially available pericardial valve, were disappointing because of high rate cusp tears during the first decade after implantation. The enthusiasm for this type of bioprosthetic valve was further hampered by the premature failure of the Hancock pericardial valve. The long-term results of aortic valve replacement with the Carpentier-Edwards pericardial valve, which was introduced in 1981, indicated that that valve was durable and the issue of cusp tears had been resolved by an appropriate design. This knowledge prompted surgeons to revisit the merits of pericardial valves for mitral valve replacement and several other pericardial valves are now commercially available. The largest data on long-term results are with the Carpentier-Edwards pericardial mitral valve. The reported freedom from structure valve failure ranged from 69% to 85% at 10 years in patient population with mean age of 60 to 70 years. Young age is a major determinant of valve failure, which is largely due to calcification. There are also long-term data, albeit more limited on the Sorin Pericarbon and Mitroflow valves used for mitral valve replacement. This paper review the published experience with various pericardial bioprosthetic valves used for mitral valve replacement during the past 3 decades.     

Have the results of mitral valve replacement improved?

The operative mortality following valvular surgery remains substantial for specific high risk groups despite recent improvement in surgical techniques, anesthetic managements, and postoperative care. To test the contention that the results of valvular surgery are better in recent years, we examined patients undergoing isolated or combined mitral valve replacement in an earlier era (1980-1984; n = 68) and a later era (1985-1989; n = 106). There were no significant differences concerning the clinical characteristics between an earlier era and a later era, although patients in an earlier era were more seriously in hemodynamics, and in a later era were older, a higher prevalence of reoperations and a combined tricuspid valve surgery. The operative mortality was 10.3% in an earlier era, 6.6% in a later era, and so it is not significantly improved in a recent 5 years, however the incidence of premature death (death within 30 days) except valve re-replacement was significantly improved. Using univariate multiple logistic model, the predictors for operative death after mitral valve replacement in an earlier era were advanced NYHA functional class, larger CTR, higher systolic pulmonary pressure and pulmonary capillary wedge pressure, associated preoperative organ dysfunction and heart lung machine time. In a later era, these were advanced NYHA functional class, higher right atrial mean pressure, associated preoperative organ dysfunction, valve re-replacement, heart lung machine time and aortic cross clamp time. Multivariate analysis including these significant factors could not demonstrated the most independent predictors of operative mortality after mitral valve replacement in both an earlier era and a later era.(ABSTRACT TRUNCATED AT 250 WORDS)     

Have the results of mitral valve replacement improved?

To test the contention that the results of cardiac surgery are better in recent years, we analyzed patients undergoing isolated or combined mitral valve replacement in an earlier era (1975 to July, 1979; n = 478) and a later era (July, 1979, to July, 1983; n = 341). Patients in the later era were older, had a higher left ventricular end-diastolic pressure, and a higher prevalence of ischemic mitral valve disease and a lower one of rheumatic mitral disease. Patients operated on in the later era had, on the average, longer and more extensive operations. Patients in the later era had a slightly but inconclusively lower 2 week and 4 1/2 year survival rate than those in the earlier era; their hazard functions were similar. A higher proportion of the deaths in the later era than in the earlier era were due to chronic heart failure. However, neither the era nor the specific year in which a patient was operated on was a risk factor for death in a multivariate analysis. By contrast, in many subsets of patients with congenital and ischemic heart disease, the risks have been shown to be lower in the current era. Continuing delay in advising mitral valve replacement and imperfections in the methods for myocardial protection are probably responsible for this lack of improvement across time.     

Long-term follow-up of Bj?rk-Shiley mitral valve replacement. 10 years' experience

Retrospective analysis was made of 176 patients who received a Bj?rk-Shiley mitral valve replacement in the period 1973 through 1982. Actuarial cumulative curves showed the 10-year and 5-year survival rates to be 79 +/- 3.4%. The functional status at follow-up was better than preoperatively in 77.1% of the patients. The hospital mortality was 9.1% and the late mortality was 3.6/100 patient years. Early complications included disc entrapment against the ventricular wall in three cases, wedging of chorda between disc and valve rim in two and posterior perforation of the left ventricle in three patients. There was no structural valve damage. Calculated per 100 patient years, the incidence of thromboembolism was 2.5, endocarditis 1.4 and prosthetic leak 1.8. One thrombosed valve was successfully replaced by a new prosthesis 11 years after the initial implantation. Jamming of the disc by tissue over-growth necessitated a new valve implantation in one case. The incidence of early valve-related complications was high, but the long-term results were comparable with those from other mechanical valves. One early complication--disc entrapment against the ventricular wall--may be avoided by use of a sufficiently small valve if the ventricle is small and thickened.     

Intermediate results of isolated mitral valve replacement with a Biocor porcine valve

BACKGROUND: We analyzed the intermediate experience, survival, and prosthetic complications of patients who received the Biocor valve, a new-generation porcine valve, in the mitral position. METHODS: At the University of Padua, between May 1992 and January 2004, 154 consecutive patients (102 female and 52 male patients; mean age, 72.3 +/- 6 years; age range, 37-86 years) received 158 mitral Biocor prostheses (Biocor Industria e Pesguisa Ltda, Belo Horizonte, Brazil). Thirty-five percent of the patients had previous mitral operations, 24% had coronary artery bypass grafting, and 34.6% had other procedures. Median preoperative New York Heart Association class was III. Echocardiography was performed in 75% of the long-term survivors. Follow-up included 609.4 patient-years and was 100% complete, with a median time of 4 patient-years (range, 0.02-11.3 years). At 8 years, 20 (14%) of 142 operative survivors were still at risk. RESULTS: Early mortality was 13.6%. According to univariate analysis, New York Heart Association class III to IV, ejection fraction of less than 40%, urgency, male sex, and coronary artery bypass grafting were significant perioperative risk factors. Eight- and 10-year actuarial survival was 51.1% +/- 5.6% (40 deaths). Eight-year actuarial freedom from valve-related death, thromboembolism, anticoagulant-related hemorrhage, endocarditis, paravalvular leak, and valve-related complications were 85.2% +/- 5%, 85.7% +/- 4.4%, 92.6% +/- 3.7%, 94.1% +/- 3%, 91.8% +/- 3%, and 70.2% +/- 5.7%, respectively. Freedom from structural valve deterioration was 100%. Actual freedom from reoperation was 93.2% +/- 2.2%. By Doppler echocardiography, the peak and mean transprosthetic gradients were 15 +/- 5 mm Hg and 6.3 +/- 3 mm Hg, respectively (mean follow-up, 4.2 +/- 2.7 years). CONCLUSION: At intermediate follow-up, the Biocor prosthesis in the mitral position showed excellent results in terms of valve durability when compared with other second-generation tissue valves.