Objective: To compare percutaneous transluminal coronary angioplasty (PTCA) and stent implantation with respect to the long-term changes they induce in the newly formed endothelium in porcine coronary arteries by studying both morphological and functional parameters of the endothelium at 2 weeks and 3 months after intervention.
Background: Problems affecting PTCA or stent implantation have been overcome to a large extent by means of better techniques and the availability of new drugs. Late problems, however, still exist in that restenosis affects a large number of patients. With an increasing number of patients being treated with stents, the problem of in-stent restenosis is of even greater concern, as this seems difficult to treat. A functional endothelial lining is thought to be important in controlling the growth of the underlying vascular tissue. We hypothesized that the enhanced neointimal hyperplasia observed after stenting is associated with a more pronounced and prolonged endothelial dysfunction.
Methods: Arteries were analyzed using a dye-exclusion test and planimetry of permeable areas. Thereafter, the arteries were processed for light and scanning electron microscopy for assessment of morphology and proliferative response.
Results: Leakage of the endothelium for molecules such as Evans blue-albumin as well as prolonged endothelial proliferation is observed as late as 3 months after the intervention, and is more pronounced after stenting. Permeability is associated with distinct morphologic characteristics: endothelial retraction, the expression of surface folds, and the adhesion of leukocytes.
Conclusions: Stenting especially decreases long-term vascular integrity with respect to permeability and endothelial proliferation, and is associated with distinct morphologic characteristics.