Quantitative analysis of neovascularization of different PTFE-implants.

The process of neovascularization was analyzed in vivo in different expanded polytetrafluoroethylene (e-PTFE) implants which are frequently used in cardio-thoracic and vascular surgery. We have used the model of the hamster dorsal skinfold chamber which allows quantitative analysis of the microcirculation by means of intravital fluorescence microscopy. Pieces of approximately 1 mm2 of the cardiovascular patch (CVP, fibril length: 30 microns; n = 21), surgical membrane (SM, fibril length: 1 micron; n = 16), and soft tissue patch (STP, fibril length: 22 microns; n = 12) were implanted into the skinfold chambers. On day 10 after implantation, the functional density of newly formed microvessels was significantly (P less than 0.05) higher in CVP (145.0 +/- 10.9 cm-1) as compared to SM (688 +/- 13.9 cm-1) and STP (86.9 +/- 21.2 cm-1). In addition, CVP revealed a larger zone of neovascularization (311.6 +/- 19.4 microns) and the tightest integration (dynamic breaking strength: 17.9 +/- 3.0 cN/mm2) into the perigraft tissue, while SM demonstrated only few microvessels and no integration (6.0 +/- 1.9 cN/mm2) into the perigraft. None of the three different PTFE-implants revealed transmural ingrowth of capillaries. The internodal distance of PTFE implants seems to be the most important factor for neovascularization. Surgical membrane used for the replacement of passive biological membranes demonstrated, as is its purpose, little neovascularization and no integration into the perigraft tissue.(ABSTRACT TRUNCATED AT 250 WORDS)