title: Material properties of CorCap passive cardiac support device.
abstract: BACKGROUND
  Myocardial function deteriorates during ventricular remodeling in patients with congestive heart failure (HF). Ventricular restraint therapy using a cardiac support device (CSD) is designed to reduce the amount of stress inside the dilated ventricles, which in turn halts remodeling. However, as an open mesh surrounding the heart, it is unknown what the mechanical properties of the CSD are in different fiber orientations.
  
  
  METHODS
  Composite specimens of CorCap (Acorn Cardiovascular, Inc, St. Paul, MN) CSD fabric and silicone were constructed in different fiber orientations and tested on a custom-built biaxial stretcher. Silicone controls were made and stretched to detect the parameters of the matrix. CSD coefficients were calculated using the composite and silicone matrix stress-strain data. Stiffness in different fiber orientations was determined.
  
  
  RESULTS
  Silicone specimens exerted a linear behavior, with stiffness of 2.57 MPa. For the composites with 1 fiber set aligned with respect to the stretch axes, stiffness in the direction of the aligned fiber set was higher than that in the cross-fiber direction (14.39 MPa versus 5.66 MPa), indicating greater compliance in the cross-fiber direction. When the orientation of the fiber sets in the composite were matched to the expected clinical orientation of the implanted CorCap, the stiffness in the circumferential axis (with respect to the heart) was greater than in the longitudinal axis (10.55 MPa versus 9.70 MPa).
  
  
  CONCLUSIONS
  The mechanical properties of the CorCap demonstrate directionality with greater stiffness circumferentially than longitudinally. Implantation of the CorCap clinically should take into account the directionality of the biomechanics to optimize ventricular restraint.
authors.affiliation: Department of Surgery, University of California at San Francisco and San Francisco Veterans Affairs Medical Center, San Francisco, California, USA.
authors.forename: Sam
authors.initials: S
authors.lastname: Chitsaz
authors.forename: Jonathan F
authors.initials: JF
authors.lastname: Wenk
authors.forename: Liang
authors.initials: L
authors.lastname: Ge
authors.forename: Andrew
authors.initials: A
authors.lastname: Wisneski
authors.forename: Aart
authors.initials: A
authors.lastname: Mookhoek
authors.forename: Mark B
authors.initials: MB
authors.lastname: Ratcliffe
authors.forename: Julius M
authors.initials: JM
authors.lastname: Guccione
authors.forename: Elaine E
authors.initials: EE
authors.lastname: Tseng
mesh_terms: D006333:Heart Failure / Q000503:physiopathology / Q000601:surgery*; D006353:Heart-Assist Devices; D006801:Humans; D008422:Materials Testing; D011474:Prosthesis Design; D020257:Ventricular Remodeling