title: Poor clinical performance of the Wessex porcine heart valve bioprosthesis at nine years' follow up.
abstract: OBJECTIVE
  To assess the long term performance of the Wessex porcine bioprostheses implanted in a consecutive series of patients.
  
  
  METHODS
  A retrospective case series.
  
  
  METHODS
  Between January 1985 and July 1991, 184 Wessex bioprostheses (78 mitral, 102 aortic, and 4 tricuspid) were implanted in 150 patients. The patients were 55% (83/150) male and 45% (67/150) female; mean age was 60 (SD 10) years.
  
  
  RESULTS
  Hospital mortality was 9.3% (14/150). Total follow up was 696 patient-years (mean 4.7 years per patient). Linearised rates (events per 100 patient-years (SEM) for postoperative complications for patients with isolated mitral valve replacement, isolated aortic valve replacement, and multiple valve replacement were, respectively: late mortality: 4.7 (1.6), 3.3 (0.9), and 4.9 (1.9); thromboembolism: 5.8 (1.8), 3.0 (0.9), and 2.8 (1.4); valve thrombosis: 1.0 (0.7), 0.3 (0.3), and 0.7 (0.7); structural failure: 5.8 (1.7), 1.9 (0.7), and 7.1 (2.2). Actuarial freedom from complications at nine years (70% confidence interval) was: late mortality: 61 (9)%, 57 (13)%, and 59 (12)%; thromboembolism and valve thrombosis: 71 (9)%, 79 (6)%, and 81 (8)%; structural failure: 33 (14)%, 50 (16)%, and 12 (14)%; all valve related morbidity/mortality: 31 (10)%, 21 (11)%, and 7 (9)%. Stent fractures appeared in 11 of 17 explanted prostheses; actuarial freedom from stent fracture at nine years was 66 (12)%.
  
  
  CONCLUSIONS
  The Wessex bioprosthesis is associated with high thrombogenicity, early structural dysfunction, and a high valve related morbidity/mortality which justifies very close follow up of patients fitted with them.
authors.affiliation: Department of Cardiovascular Surgery, University Hospital Marques de Valdecilla, University of Cantabria, Santander, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Hurlé
authors.forename: J F
authors.initials: JF
authors.lastname: Nistal
authors.forename: J M
authors.initials: JM
authors.lastname: Revuelta
mesh_terms: D001021:Aortic Valve; D001705:Bioprosthesis / Q000401:mortality*; D006328:Cardiac Catheterization; D004452:Echocardiography; D004697:Endocarditis, Bacterial / Q000150:complications; D005260:Female; D005500:Follow-Up Studies; D006350:Heart Valve Prosthesis / Q000009:adverse effects / Q000401:mortality*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008943:Mitral Valve; D011474:Prosthesis Design; D011475:Prosthesis Failure; D016459:Prosthesis-Related Infections; D012189:Retrospective Studies; D015607:Stents; D013923:Thromboembolism / Q000150:complications; D016896:Treatment Outcome; D014261:Tricuspid Valve