Browsing by Author "Guarda, E"

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    Extracellular matrix collagen synthesis and degradation following coronary balloon angioplasty
    (1996) Guarda, E; Katwa, LC; Campbell, SE; Tanner, MA; Webel, RM; Laughlin, H; Jenkins, S; Myers, PR
    Percutaneous transluminal coronary angioplasty is associated with intimal hyperplasia and extracellular matrix deposition of collagen, leading to restenosis in a significant number of cases. The purpose of the present study was to determine the effects of balloon angioplasty on extracellular matrix collagen content and collagenase activity in a porcine coronary artery restenosis model 6 weeks following balloon injury. We tested the hypothesis that in balloon-injured arteries the neointimal extracellular matrix was characterized by increased collagen content and decreased metalloproteinase activity relative to non-injured arteries. Male miniswine maintained on a high cholesterol diet underwent cardiac catheterization and double balloon injury to the right and left circumflex coronary arteries. The coronary arteries were either pressure-perfusion-fixed and prepared for histological examination, or dissected free of adventitia for further collagen and matrix metalloproteinase studies. Collagen synthesis in balloon-injured coronary arteries was compared to non-injured arteries using Northern blot analysis and histochemical stains. Comparative studies on differences between balloon-injured and non-balloon-injured arterial matrix metalloproteinase activity were done using zymography. Balloon angioplasty arterial injury resulted in a significant increase in type I collagen mRNA expression, with increased collagen deposition in the extracellular matrix. In contrast, matrix metalloproteinase activity was markedly decreased. The results suggest that the increased neointimal extracellular matrix observed late in the injury response may be due to not only increased collagen synthesis, but also reduced degradation. The failure to achieve a balance between the synthesis and degradation of extracellular matrix collagen could serve as an important mechanism responsible for restenosis. (C) 1996 Academic Press Limited
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    Oral rapamycin to prevent human coronary stent restenosis
    (2004) Guarda, E; Marchant, E; Fajuri, A; Martínez, A; Morán, S; Mendez, M; Uriarte, P; Valenzuela, E; Lazen, R
    Background Recent human trials with rapamycin-eluting stents have shown very low restenosis rates. However, the high costs of these devices preclude their use in routine angioplasty, especially when considering multiple stenting. We evaluated whether orally administered rapamycin inhibits in-stent neointimal growth in patients with unstable angina.
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    Predictors of radial artery patency for coronary bypass operations
    (ELSEVIER SCIENCE INC, 2001) Moran, SV; Baeza, R; Guarda, E; Zalaquett, R; Irarrazaval, MJ; Marchant, E; Deck, C
    Background. Few data exist regarding angiographic predictors of radial artery patency for coronary bypass grafting, and the benefit of calcium antagonists is not clear.
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    Relation of stenting to decreased coronary blood flow during primary angioplasty in acute myocardial infarction
    (2001) Escobar, J; Guarda, E; Marchant, E; Fajuri, A; Martínez, A; Pichard, A
    In primary angioplasty of acute myocardial infarction, stent implantation decreased coronary blood flow in a third of patients, caused no change in another third, and improved coronary blood flow in the last third.