title: Sutured calf pericardium: influence of the type and angle of the suture on mechanical behavior.
abstract: Careful selection of the biological tissue to be used in cardiac bioprostheses and a thorough knowledge of its mechanical behavior, facilitating both the prediction of this behavior and the interactions between the tissue and the other materials employed, is the best approach to designing a durable implant. For this purpose, a study involving uniaxial tensile testing of calf pericardium was carried out. Two sets of three contiguous strips of tissue were obtained from each pericardial membrane, to perform a total of 144 trials. Two samples were sewn with one of four commercially available suture materials: Gore-Tex, nylon, Prolene and silk. In each set of three samples, the center strip remained intact and unsutured to serve as a control, while the left-hand strip was sutured at a 45 degrees angle with respect to the longitudinal axis and the right-hand strip was sewn at a 90 degrees angle. All the samples were tested until rupture. The results demonstrated a significant loss of mean load (p<0.01) in the sutured samples at rupture. The angle of the suture had no influence on these results, although the stress/strain curves showed that, as the tensile stress increased, the mechanical behaviors were less uniform. The rupture of the collagen fibers could explain this phenomenon. The pericardium sutured with Gore-Tex presented a greater strain, or deformation (elongation), at lower levels of stress, regardless of the angle of the suture. The tissue selection criteria, based on the use of paired samples, enabled a correct prediction of the mechanical behavior of the tissue, with excellent correlation coefficients (>0.98) and a high degree of homogeneity in the results.
authors.affiliation: Cirugía Experimental, Clínica Puerta de Hierro, Madrid, Spain. josempaez@telefonica.net
authors.forename: J M García
authors.initials: JM
authors.lastname: Páez
authors.forename: E Jorge
authors.initials: EJ
authors.lastname: Herrero
authors.forename: M Martín
authors.initials: MM
authors.lastname: Maestro
authors.forename: A
authors.initials: A
authors.lastname: Rocha
authors.forename: B
authors.initials: B
authors.lastname: Arenaz
authors.forename: J L
authors.initials: JL
authors.lastname: Castillo-Olivares
authors.forename: A Carrera
authors.initials: AC
authors.lastname: Sanmartín
authors.forename: A
authors.initials: A
authors.lastname: Cordon
authors.forename: I
authors.initials: I
authors.lastname: Millán