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Biomedical subjects

B Barratt-Boyes

Publications and source records attributed to B Barratt-Boyes.

6 recordsLinked to original sources
PubMed1996

Tears in bioprosthetic heart valve leaflets without calcific degeneration.

BACKGROUND AND AIM OF THE STUDY: The mechanism of structural failure of bioprosthetic valves is still not clearly understood. This study was undertaken to assess pure leaflet tear as a mode of failure in porcine and pericardial bioprostheses. METHODS: Of 246 bioprosthetic valves (109 porcine, 137 pericardial) implanted between 1975 and 1991, 101 had to be explanted and served as the study population. RESULTS: The reasons for valve failure were calcific degeneration in 73, pure tear in 12, and endocarditis in 10. Six other patients had a perivalvar leak. The mean age at operation was 32 years. Freedom from degeneration at 10 years was 45 +/- 7% and from pure tear it was 92 +/- 2%. The hazard functions were strikingly different, as that for degeneration showed a progressive increase while that for pure tear peaked at six years post-implant. The mean age of the patients with pure tear was 41 years and for degeneration it was 24 years (p = 0.00001). The reasons for the difference in hazard function are discussed. The characteristic clinical features of pure tear allow clinical diagnosis in the majority of patients. CONCLUSION: Pure tear is the result of uneven tissue loading with tearing occurring at sites of maximal stress. The four possible mechanisms in pericardial valves are (a) intense stress concentration at the top of the stent post (commissure); (b) compression stress below the top of the post; (c) abrasion stress in tissue mounted outside the frame; and (d) increased bending stresses on leaflet opening. In stent-mounted porcine valves, pure tear is related to incorrect mounting or to increased bending stresses.

Actuarial Analysis↗
PubMed1992

Aortic valve replacement for active infectious endocarditis in 108 patients. A comparison of freehand allograft valves with mechanical prostheses and bioprostheses.

A total of 108 patients hospitalized with active (acute) endocarditis on either a native aortic valve (n = 66) or a previously inserted replacement device (n = 42) underwent aortic valve replacement because they were too ill for hospital discharge. A nonstented aortic allograft valve was used in 78 patients and prosthetic (mechanical or bioprosthetic) valves in 30 patients. The survival rate was 82% at 1 months, 73% at 1 year, 64% at 5 years, and 36% at 15 years. It was better in patients with native valve endocarditis than prosthetic valve endocarditis. The incremental risk factors for death in the early phase postoperatively were older age at operation, higher New York Heart Association functional class, and a larger number of previous aortic valve procedures. There were 13 episodes of recurrent endocarditis, giving an actuarial freedom of 80% at 10 years. The hazard function for recurrent endocarditis had only a low constant phase when allograft valves were used, which contrasted with the existence of a high peaking early phase (in addition to the constant phase) when prosthetic devices were used. No risk factors for recurrent endocarditis were found in patients receiving a prosthesis, and "localized" versus "extensive" endocarditis was the only risk factor when an allograft was used. Reoperation was performed in 24 patients for a variety of reasons, and freedom from reoperation was 61% at 10 years. It is concluded that the allograft valve is the valve of choice when aortic valve replacement is required for active endocarditis.

Adult↗
PubMed1977

Isolated mitral replacement with stent-mounted antibiotic-treated aortic allograft valves.

The results of valve replacement with a stent-mounted antibiotic-treated aortic allograft valve are reported in 129 patients with isolated mitral valve disease. Of these patients, 70 per cent were in N.Y.H.A. Class IV. The hospital mortality rate was 3.9 percent. The cumulative complication-free rate at 5 years was only 37 percent as 21 percent died late, a further 15 percent were alive following reoperation, 4 percent had an embolic episode, 4 percent were alive with important incompetence, and 20 percent had unimportant incompetence. Proved valve failure was due mainly to detachment of the aortic wall remnant of the valve from the pillar of the rigid metal stent (16 percent incidence at 5 years) and methods for preventing this complication are discussed. Because of these complications the use of this device in the mitral position has been discontinued.

Adolescent↗
PubMed1972

Homograft valves.

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Anti-Bacterial Agents↗