[Recurrent stenosis following coronary angioplasty. Clinical, cell biological and molecular aspects].

Percutaneous transluminal coronary angioplasty by balloon dilatation (PTCA) has proved to be the standard procedure for non-operative removal of coronary artery stenoses. Since the initial description and application by Andreas Grüntzig, the results of this procedure are excellent with an acute success rate of 90-96%, a rate of severe acute complications of 1% and less, and a procedure-related death rate below 1%, mainly due to considerable technical improvements and greater experience of the interventional cardiologists. On the other hand, the restenosis rate following PTCA could not be significantly lowered. In recent years a number of alternative angioplasty devices has been developed aimed at-among other indications-reducing the restenosis rate following PTCA by a "less traumatic" vessel angioplasty. These include radiofrequency angioplasty (RFCA), high frequency rotational angioplasty (HFRCA), excimer-laser angioplasty (ELCA), directional atherectomy (DCA), as well as implantation of intravascular stents. Based on more or less extensive experiences from the literature, the aim at lowering the recurrency rate by the latter procedures has been missed, despite the fact that particularly ELCA and HFRCA were used to reduce stenoses in lesions unsuitable for balloon catheter dilatation. There is a trend of lowering the recurrence rate with the implantation of coronary stents. The benefit of this procedure, however, is at the expense of an increased rate of acute stent thrombosis and by local acute bleeding problems quite often requiring surgical repair. The cellular biological mechanisms following balloon angioplasty are only partially understood. Among these are a number of interactive processes like cell adhesion, coagulation, vascular contraction, cell migration, cell proliferation, and synthesis of extracellular matrix. In this respect, migration and proliferation of smooth muscle cells represent a key process for the development of restenosis. In addition, endothelial denudation represents a stimulus for migration and proliferation of smooth muscle cells. Rapid and efficient reendothelialization may counteract this process. Recent progress of modern biology has provided new concepts and methodological tools for the molecular analysis of vascular remodeling. It has been shown that specialized cellular functions such as proliferation, migration, and production of extracellular matrix can be mediated by growth factors such as platelet-derived growth factor (PDGF), basic fibroblast growth factor (bFGF) or transforming growth factor-beta (TGF-beta).(ABSTRACT TRUNCATED AT 400 WORDS)