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

The effects of decellularization and cross-linking techniques on the fatigue life and calcification of mitral valve chordae tendineae

In cases of severely diseased mitral valves (MV), the required treatment is often valve replacement. Bioprosthetic and stentless replacement valves are usually either fully or partially composed of animal derived tissue treated with a decellularization process, a cross-linking process, or both. In this study, we analysed the effects of these treatments on the fatigue properties of porcine MV chordae tendineae (CT), as well as on the calcification of the CT using an in vitro technique. CT were tested in 4 groups; (1) native, (2) decellularized (DC), (3) decellularized and cross-linked with glutaraldehyde (DC-GTH), and (4) decellularized and cross-linked with 1-ehtyl-3-(3-dimethylaminopropyl) carbodiimide (EDC)(DC-EDC). CT were tested in both uniaxial tension, and in fatigue at 10MPa peak stress (1Hz). The cycles to failure (mean±SD) for the four groups are as follows; Native- 53,397±55,798, DC- 28,013±30,634, DC-GTH- 97,665±133,556, DC-EDC- 318,601±322,358. DC-EDC CT were found to have a slightly longer fatigue life than the native and DC groups. The DC-EDC group also had a marginally lower dynamic creep rate, meaning those CT elongate more slowly. After in vitro calcification, X-ray microtomography was used to determine relative levels of calcification. The DC-EDC and DC-GTH groups had the lowest volume of calcific deposits. Under uniaxial testing, the ultimate tensile strength (UTS) of the DC-GTH CT was statistically significantly reduced after calcification, while the UTS was relatively unchanged for the DC-EDC group. Overall, these results indicate that a treatment of decellularization plus cross-linking with EDC may improve the fatigue life of porcine CT, reduce the rate of elongation, and help the CT resist the negative effects of calcification. This may be a preferable treatment in the preparation of porcine MVs for the replacement of diseased MVs.

Mid-term outcome with pericardial patch augmentation for redo left atrioventricular valve repair in atrioventricular septal defect†

OBJECTIVES

Recurrent left atrioventricular valve (LAVV) regurgitation after atrioventricular septal defect (AVSD) repair is a difficult technical issue. This study exposes the various techniques successively employed to repair the recurrent LAVV regurgitation and their different outcomes. Emphasis however will be put on the new technique used in our unit called cleft patch augmentation, which has been used continuously since 1998 in the anatomical context of normal papillary muscles (NPMs).

METHODS

This is a retrospective follow-up study using a Cox regression model for risk analyses from November 1991 to July 2008, including 45 patients who underwent reoperation for LAVV regurgitation after AVSD repair. Of those, 3 patients were lost to follow-up; therefore, 42 patients were included in the study. With regard to the AVSD morphology, there were partial AVSD in 12, complete AVSD in 30.

RESULTS

Age at the primary valve repair was 1.5 ± 2.1 years and the time span to the reoperation was 7.1 years in median (0.41-12.3 years). Age at the first reoperation was 10.1 ± 6.8 years. Median follow-up after the reoperation was 7.4 years. Three patients died in the follow-up period. Freedom from second reoperation at 10 years was 72.8% [59.5-89.0% of 95% confidence interval (CI)]. Of 37 patients with NPMs, freedom from reoperation at 10 years was 59.4% (37.2-94.7% 95% CI) in cleft closure group whereas, in the cleft patch augmentation group, it was 92.3% (78.9-100% 95% CI) (P = 0.04). Five patients required valve replacement.

CONCLUSIONS

Surgical result for the redo LAVV repair had good outcomes. In the NPM group, the cleft patch augmentation technique had better results. Various techniques may have to be performed in combination according to the morphological features.

Structural deterioration of the cryopreserved mitral homograft valve

OBJECTIVE

The aim of this study was to evaluate the long-term fate of the cryopreserved mitral homograft focusing on structural valve deterioration.

METHODS

Homograft replacement of the mitral valve was performed in 106 patients. The causes of mitral disease were rheumatic disease (n=75), endocarditis (n=24), and others (n=7). There were 40 partial homografts and 66 total homografts.

RESULTS

Mean follow-up was 9.3+4.7 years (up to 17.8 years). There were 5 early (<3 months) and 15 late deaths. There have been 5 early (<3 months) and 30 late reoperations. Five patients had endocarditis, and 5 patients had an ischemic/hemorrhagic event. Compared with baseline, follow-up echography showed progression of mitral regurgitation grade (from 0.4 to 1.3; P<.001) with stenosis (elevated gradient: from 3.9 to 7.0 mm Hg; P<.001) and decreased valve area (from 2.3 to 1.7 cm2, P<.001). Freedom from structural valve deterioration was 90%, 76%, and 65% at 5, 10, and 15 years, respectively. Structural valve deterioration was more frequent in total homografts (P=.018 vs partial homografts) and in case of pregnancy (P=.016 vs no pregnancy). Stenosis related to structural valve deterioration was more pronounced for age less than 40 years (P=.03) and ring size 30 mm or less (P=.002). Pathologic analysis of the explanted homografts almost invariably showed dense fibrosis with calcification and no cellularity.

CONCLUSIONS

Mitral homografting was accomplished with early echographic results similar to those of valve repair. Structural valve deterioration produced mixed stenosis with insufficiency, and its incidence was comparable to that of bioprostheses structural valve deterioration. An improvement in the preservation mode of valvular homografts is warranted.

Update on the mitral pulmonary autograft

Between July 1997 and August 2004, 92 patients with irreparable mitral valves underwent replacement with a pulmonary autograft. This report brings the follow-up data of these patients up to date. Eighty-eight patients had a successful Ross II operation; 4 were lost to follow-up. The mean follow-up period was 94 months. Transesophageal echocardiography revealed a successful outcome in all 88 patients immediately after the operation. Operative mortality was 4.6%, and late mortality definitely related to the operation was 12.5%. At a mean follow-up of 94 months, freedom from structural valve deterioration (significant mitral stenosis and/or regurgitation) was 93.4%, freedom from reoperation was 92.0%, and freedom from all causes of death was 82.9%. Two autografts were explanted because of endocarditis. Two patients developed significant pulmonary stenosis, one of whom underwent operative repair. These data compare favorably with those of mitral valve replacement using modern bioprostheses. This procedure remains an option for the relatively young patient when life-long anticoagulation is contraindicated or impractical. It is also an option to consider in infants with complex irreparable mitral valve disease.

Analysis of 92 mitral pulmonary autograft replacement (Ross II) operations

OBJECTIVE

The study objective was to find a mitral valve substitute that does not require lifelong anticoagulation and is not affected by tissue degeneration in the long term.

METHODS

Between July 14, 1997, and August 8, 2004, a total of 92 patients with irreparable mitral valve disease underwent mitral valve replacement with the pulmonary autograft encased within a Dacron tubing for support. In 4 patients, the autograft had to be sacrificed at the initial operation. Of the remaining 88 patients, 62 were female, and the age ranged from 4 to 64 years (mean 39 years). Eighty-six patients had rheumatic mitral disease, and 2 patients had congenital mitral disease.

RESULTS

Operative transesophageal echocardiography initially showed adequate valve characteristics (mean valve area 2.8 cm2, mean gradient 3.9 mm Hg, no significant regurgitation) in all 88 patients. Operative mortality was 4.6%, and late mortality definitely related to the operation was 7.9%. Four patients were lost to follow-up; the mean follow-up was 60 months. Progressive regurgitation and stenosis developed in 9 patients over 2 to 5 years, 4 of whom had their grafts explanted. The autograft was explanted in 1 patient because of endocarditis. Mild pulmonic stenosis developed in 3 patients, and critical pulmonic stenosis developed in 1 patient. At 5 years follow-up, freedom from degeneration was 93.4%, freedom from reoperation was 94.2%, and freedom from all death was 86.0%.

CONCLUSION

Although the Ross II operation is difficult and harbors significant risk, it remains an option for patients with irreparable mitral disease who have a long life expectancy and who cannot be placed on lifelong anticoagulation.

Mitral valve replacement with Ross II technique: initial experience

BACKGROUND

Pulmonary autograft mitral valve replacement (PA-MVR) was introduced clinically by Ross in 1967, but has been rarely utilized in North America and Europe. The aim of this study is to review our early experience with PA-MVR.

METHODS

Since June 2002, 8 patients (7 female and 1 male) between 12 to 46 years of age with outgrown mechanical valves (n = 3) failed MV repair for rheumatic or congenital MV disease (n = 4) and irreparable bileaflet myxoid prolapse (n = 1), underwent PA-MVR. The pulmonary autograft was harvested and replaced using a pulmonary homograft. The autografts were mounted within a woven Dacron graft 6-8 mm greater in diameter than the autograft annulus diameter on a preoperative echocardiogram. The graft's external surface was covered with fresh autologous pericardium.

RESULTS

There were no deaths. Intraoperative echocardiography confirmed a mean MV gradient of 4 mm Hg with trivial (n = 7) or mild (n = 1) regurgitation. Follow-up (range, 13 to 36 months) echocardiography in 4 patients showed no increase in MV gradient or regurgitation. One patient with severe myxoid degeneration and one patient with rheumatic disease, both with systemic hypertension, developed progressive regurgitation due to stretching of a single autograft leaflet producing prolapse. One patient developed a moderate gradient due to retention of excessive native mitral leaflet and subannular chordal tissue. Three of 4 patients have required PA-MVR replacement with mechanical valves 6 to 14 months post-PA-MVR. One asymptomatic patient with mild to moderate mitral regurgitation is being followed after treatment of her systemic hypertension.

CONCLUSIONS

Pulmonary autograft mitral valve replacement offers selected patients a potentially lifelong autologous valve without the need for long-term anticoagulation. The PA-MVR technique deserves careful consideration in younger patients in sinus rhythm. Postoperative systemic hypertension should be treated aggressively to prevent excessive stress on the pulmonary autograft particularly in the early postoperative months.

Congenital mitral valve surgery: techniques and results

PURPOSE OF REVIEW

Congenital lesions of the mitral valve are rare. Conservative surgery is recognized as the best option. In complex anatomy, however, replacement is the only solution to achieve an acceptable result. This review aims to study the long-term follow-up of classical treatments, conservative or replacement, and to examine new technical advances.

RECENT FINDINGS

The long-term results of conservative surgery are confirmed with a low incidence of reoperation except in mitral valve stenosis. The Ross II operation using a pulmonary autograft is a difficult technique that may be useful in the youngest patient group when prosthetic devices cannot be used.

SUMMARY

In the last few years, surgery of congenital mitral valve lesions has gained from echocardiography, which shows the exact function and anatomy of the mitral valve. The tendency is to avoid multistage operations. Valve replacement by biologic material (Ross II) is still under clinical evaluation.

Severe valvular regurgitation and antiphospholipid antibodies in systemic lupus erythematosus: A prospective, long-term, followup study

OBJECTIVE

To assess whether the presence of antiphospholipid antibodies is related to the incidence and progression of severe valvular dysfunction and the need for valve replacement in patients with systemic lupus erythematosus (SLE).

METHODS

In this prospective, long-term followup study, the initial echocardiographic findings in a cohort of 61 consecutive SLE patients were compared with those of 40 matched controls. All patients were serially evaluated for 14 +/- 3 years and had a followup echocardiogram 8 +/- 3 years after the initial evaluation. Serial determinations of anticardiolipin antibodies and lupus anticoagulant were performed in all cases.

RESULTS

The number of SLE patients with valvular abnormalities increased from 39% to 73% between the initial and the followup echocardiography, but only 7 patients (12%) developed severe valvular regurgitation. Severe valvular regurgitation was significantly associated with the presence of high levels of IgG anticardiolipin antibodies (P = 0.001). The combined incidence of stroke, peripheral embolism, need for valve surgery, and death was 86% in patients with severe valvular regurgitation, compared with 25% in those without (P = 0.003).

CONCLUSION

In SLE patients, the presence of high levels of IgG anticardiolipin antibodies is associated with the development of severe valvular regurgitation and with a high incidence of thromboembolic events and the need for valvular surgery.

The Ross II Procedure: Pulmonary Autograft in the Mitral Position

The surgical management of mitral valve disease in women of childbearing age, young patients, and children with congenital mitral valve defects is made difficult by the prospect of lifelong anticoagulation. We suggest the use of a pulmonary autograft in the mitral position (Ross II procedure) as an alternative surgical technique. We present a review of the literature, historical perspectives, indications, selection criteria, and surgical technique for the Ross II procedure. Our literature search identified 14 studies that reported results from the Ross II operation. Performed in 103 patients, the overall in-hospital mortality was 7 (6.7%), with a late mortality of 10 (9%). Although further research is needed, current evidence suggests the Ross II operation is a valuable alternative in low-risk young patients where valve durability and the complication rate from other procedures is unsatisfactory and anticoagulation not ideal.

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.

Mitral valve replacement with the pulmonary autograft: Ross II procedure with Kabanni modification

We report our experience with pulmonary autograft replacement of the mitral valve in eight patients. Hospital mortality of 0% was reported, and there has been one autograft failure requiring replacement (mean follow-up 12 +/- 6 months). We also review the world's experience with this technique. Mitral valve replacement with a pulmonary autograft (Ross II) is safe, reproducible, and possible warranted for selected patients.