title: Single leg separation prevalence among explanted Björk-Shiley prosthetic heart valves.
abstract: OBJECTIVE
  Björk-Shiley convexo-concave (BSCC) prosthetic heart valves are believed to have been implanted in over 86,000 patients worldwide. Limited data are available on the prevalence of single leg separations (SLS) of the valves' outlet struts, a potential precursor to complete valve fracture.
  
  
  METHODS
  Data maintained by the manufacturer, including results of examinations for SLS in explanted valves, were merged with available information on the characteristics of the valve. The prevalence of SLS in the examined valves was calculated according to valve angle, size, position, and study.
  
  
  RESULTS
  Among 343 examined valves, the overall prevalence of SLS was 8.2%, but this varied significantly by valve size, being three-fold higher among 29+ mm valves than among smaller valves, with statistically non-significantly higher prevalences among mitral than aortic, and among 70 degrees than 60 degrees valves. By applying the size, position and angle-specific SLS prevalences to the worldwide valve distribution, it is estimated that SLS may be present in 6.8% (95% confidence limits 4.1-9.4%) of all BSCC valves.
  
  
  CONCLUSIONS
  These findings suggest that SLS may affect between 820 and 1,880 of the almost 20,000 BSCC valves among surviving patients worldwide. Such estimates help frame the context for potential patient screenings, should imaging and acoustic techniques to detect SLS become available.
authors: International Epidemiology Institute, Rockville, MD 20850, USA. blotw@iei.ws
authors: William J
authors: WJ
authors: Blot
authors: Lisa B
authors: LB
authors: Signorello
authors: Sarah S
authors: SS
authors: Cohen
authors: Michel A
authors: MA
authors: Ibrahim
mesh_terms: D001021:Aortic Valve / Q000601:surgery*; D006350:Heart Valve Prosthesis; D006801:Humans; D008943:Mitral Valve / Q000601:surgery*; D015995:Prevalence; D011474:Prosthesis Design; D011475:Prosthesis Failure