11 research outputs found

    Quantitative angiographic follow-up of the coronary wallstent in native vessels and bypass grafts (European experience - March 1986 to March 1990)

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    The coronary stent has been investigated as an adjunct to percutaneous transluminal coronary angioplasty to obviate the problems of early occlusion and late restenosis. From March 1986 to March 1990, 265 patients (308 lesions) were implanted with the coronary Wallstent in 6 European centers. For this study, the patients were analyzed accordin

    Angiographic follow-up after placement of a self-expanding coronary artery stent

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    BACKGROUND. The placement of stents in coronary arteries after coronary angioplasty has been investigated as a way of treating abrupt coronary-artery occlusion related to the angioplasty and of reducing the late intimal hyperplasia responsible for gradual restenosis of the dilated lesion. METHODS. From March 1986 to January 1988, we implanted 117 self-expanding, stainless-steel endovascular stents (Wallstent) in the native coronary arteries (94 stents) or saphenous-vein bypass grafts (23 stents) of 105 patients. Angiograms were obtained immediately before and after placement of the st

    Pacing-induced ventricular remodeling in the chick embryonic heart.

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    Chronic ectopic pacing in the adult heart induces myocardial hypotrophy close to the pacing site. We have recently described a similar localized decrease of compact myocardium thickness in the chick embryonic heart after 48 h of intermittent apical ventricular pacing. Here we analyze the cellular mechanisms underlying the response of the embryonic heart to pacing. Because the developing heart had been found to adjust its morphology according to functional demands by undergoing cellular hyperplasia or hypoplasia, we hypothesized that the stimulation should result in hypoplasia of the apical ventricular compartment. Morphologic analysis of hearts submitted to 18 h of effective pacing during 48 h showed a mild to moderate ventricular dilatation, a 28% decrease in the apical compact layer thickness with no changes in other ventricular locations, and atrial wall thickening. These modifications were caused by changes in the number of cell layers, whereas cell size was similar between paced and control hearts. Analysis of proliferative activity after 24 h of pacing showed a decrease of 32% in the rate of cell proliferation limited to the apical compact layer exposed to stimulation. No ultrastructural injury or increased cell death was found. These changes were accompanied by down-regulation of the myocardial growth factor fibroblast growth factor-2 but no differences were found in the expression of platelet-derived growth factor. Thus, chronic intermittent ventricular pacing induces myocardial remodeling in the chick embryonic heart, on the basis of locally regulated rates of cell proliferation
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