A Novel Knitted Polytetrafluoroethylene Patch for Cardiovascular Surgery

Polytetrafluoroethylene (PTFE) is widely used in cardiovascular surgeries; however, postoperative complications such as thrombosis, calcification, and neointimal hyperplasia are yet to be resolved in patients. We developed two types of novel knitted PTFE patches and evaluated them using a swine model. Both patches were composed of knitted PTFE impregnated with micro-PTFE particles, and one of them was pressed after PTFE impregnation. Twenty micromini pigs were used in this study. After left lateral thoracotomy, the new patches (n = 8 for each type of patch) were implanted into the descending aorta and left atrium for the high- and low-pressure models, respectively. Clinically used expanded PTFE (ePTFE) patches were used as the control material (n = 4). The patches were explanted and histopathologically examined at 4, 12, and 24 weeks after implantation. A tensile test was also applied to the high-pressure model at 12 and 24 weeks. As a result, there was no significant difference noted in the tensile test, intimal hyperplasia thickness, or endothelialization among the three patches. In contrast, the degree of macrophage infiltration into the patches and the degree of macrophage, lymphocyte, and granulocyte infiltration outside the patches were lower in the new patches than in the control ePTFE. The degree of cellular infiltration outside new patches decreased over time. There were no significant differences between the two new patch types in these results. In conclusion, our novel knitted PTFE patch showed noninferiority in durability and intensity and less inflammatory responses than a clinically used ePTFE patch.