Biomechanical properties of two synthetic biomaterials for ventricular septal defect closure in infancy

Abstract

Ventricular septal defect (VSD) is the most common congenital heart disease (15-20%). The traditional treatment is surgical repair - VSD closure using the autologous pericard or synthetic material - polytetrafluorethylene. The aim of this research is to investigate the biomechanical properties of two synthetic materials and to biomechanicaly compare the properties of the PTFE (polytertaflourethylene) material patches - GORE TEX and BARD in vitro studies the elastic modulus E (MPa), ultimate stress ε (%) and ultimate strain σ (MPa) of both. We suspect that knitted material (BARD) would be more appropriate for myocardial tissues. Two types of PTFE patches were investigated: GORE TEX Cardiovascular Patch (GRTX), and BARD Edwards Outflow Tract Fabric knitted PTFE Patch (BARD). Every type of patch was divided into 3 subgroups: I subgroup - fresh material, II subgroup - 1 month exposed, III subgroup - exposed for 3months in sterile saline 0,9% at 37°C. The testing data were recorded with software (Testexpert 11.02, Zwick-Roell). For non-treated GRTX material σmax decreased after three months treatment from 8.62±0.21 MPa to 7.36±1.45 MPa(p<0.05). εmax increased from 16.52±1.76% to 17.26±3.54%(p=0.05). Modulus of elasticity (E) of GRTX material decrease from 84.46±11.8 MPa (for non-treated) to 59.65±5.03 MPa (p<0.05).There are statistical differences between II and III subgroup of E: 79.24±16.82 MPa and 59.65±5.03 MPa(p<0.019). σmax for non treated BARD material decreased after three months from 11,19 ± 1,03 MPa to 8,55 ± 0,62 MPa(p<0.05). εmax increased from 48.38±2.32% to 69.55±3.67%(p<0.05) after. E modulus decreased from 15.12±0.75 MPa to 8.12±0.48 MPa(p<0.05). After three months of treatment by saline the εmax of BARD material is 48.38±2.32%, but εmax of GRTX is 17.26±3.54% (p<0.05).Results show that BARD patch is not so stiff as GRTX patch, and is more suitable for the VSD closure in the first year life of children. © 2008 Springer-Verlag.