Biomedical subjects
Publications and source records attributed to V Fuster.
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Histomorphometric studies for smooth muscle cells, macrophages, tissue factor, collagen, and cell proliferation were performed on 20 atherectomy specimens from patients with in-stent restenosis and 20 specimens from patients with post-balloon PTCA restenosis. Smooth muscle cell content was larger and proliferation index was higher in in-stent restenotic tissue; macrophage, tissue factor, and collagen content were larger in post-balloon percutaneous transluminal coronary angioplasty restenotic tissue, suggesting a more cellular and proliferative response with less thrombogenic potential in human tissue from in-stent restenosis than tissue from post-balloon percutaneous transluminal coronary angioplasty restenosis.
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BACKGROUND: Although percutaneous transluminal coronary angioplasty (PTCA) is a highly effective procedure to reduce the severity of stenotic coronary atherosclerotic disease, its long-term success is significantly limited by the high rate of restenosis. Several cellular and molecular mechanisms have been implicated in the development of restenosis post-PTCA, including vascular smooth muscle cell (VSMC) activation, migration, and proliferation. Recently, our group demonstrated that rapamycin, an immunosuppressant agent with antiproliferative properties, inhibits both rat and human VSMC proliferation and migration in vitro. In the present study, we investigated (1) whether rapamycin administration could reduce neointimal thickening in a porcine model of restenosis post-PTCA and (2) the mechanism by which rapamycin inhibits VSMCs in vivo. METHODS AND RESULTS: PTCA was performed on a porcine model at a balloon/vessel ratio of 1.7+/-0.2. Coronary arteries were analyzed for neointimal formation 4 weeks after PTCA. Intramuscular administration of rapamycin started 3 days before PTCA at a dose of 0.5 mg/kg and continued for 14 days at a dose of 0.25 mg/kg. Cyclin-dependent kinase inhibitor (CDKI) p27(kip1) protein levels and pRb phosphorylation within the vessel wall were determined by immunoblot analysis. PTCA in the control group was associated with the development of significant luminal stenosis 4 weeks after the coronary intervention. Luminal narrowing was a consequence of significant neointimal formation in the injured areas. Rapamycin administration was associated with a significant inhibition in coronary stenosis (63+/-3.4% versus 36+/-4.5%; P<0.001), resulting in a concomitant increase in luminal area (1.74+/-0.1 mm2 versus 3. 3+/-0.4 mm2; P<0.001) after PTCA. Inhibition of proliferation was associated with markedly increased concentrations of the p27(kip1) levels and inhibition of pRb phosphorylation within the vessel wall. CONCLUSIONS: Rapamycin administration significantly reduced the arterial proliferative response after PTCA in the pig by increasing the level of the CDKI p27(kip1) and inhibition of the pRb phosphorylation within the vessel wall. Therefore, pharmacological interventions that elevate CDKI in the vessel wall and target cyclin-dependent kinase activity may have a therapeutic role in the treatment of restenosis after angioplasty in humans.
CONTEXT: Thrombus formation on disrupted atherosclerotic plaque is the major cause of acute coronary events. Platelet inhibitors are the mainstay of drug therapy to reduce cardiac events in patients with acute coronary syndromes. The platelet glycoprotein (GP) IIb/IIIa receptor is the final common pathway of platelet aggregation. OBJECTIVES: To review mechanisms of platelet activation and aggregation and the role of the GP IIb/IIIa receptor in the acute coronary syndromes and to summarize completed clinical trials of GP IIb/IIIa receptor antagonists. DATA SOURCES: English-language journal articles, reviews from a MEDLINE search from 1993 through 1998, as well as abstracts and presentations from major national or international cardiology meetings through November 1998. STUDY SELECTION/DATA EXTRACTION: Randomized, placebo-controlled clinical trials testing intravenous GP IIb/IIIa receptor antagonists and having more than 500 subjects were included. Data quality and validity included publication or presentation venue. DATA SYNTHESIS/CONCLUSIONS: The GP IIb/IIIa receptor is the final common pathway of platelet aggregation. Intravenous monoclonal antibody and peptide and nonpeptide antagonists of the GP IIb/IIIa receptor have been tested in randomized, placebo-controlled trials of the acute coronary syndromes and percutaneous coronary interventions. For patients undergoing percutaneous revascularization, these agents have demonstrated efficacy in reducing death, myocardial infarction, or urgent reintervention. Odds ratios of death or myocardial infarction at 30 days range from 0.42 to 0.84 for the drugs in these studies. More modest benefits have been seen in trials of IIb/IIIa receptor antagonists for patients with the acute coronary syndromes, with odds ratios for death or myocardial infarction at 30 days ranging from 0.70 to 0.89. The efficacy of oral agents for chronic GP IIb/IIIa receptor antagonism has not been sufficiently studied.
BACKGROUND: Plaque disruption and subsequent thrombus formation lead to acute coronary syndromes and progression of atherosclerotic disease. Tissue factor (TF) appears to mediate plaque thrombogenicity. Tissue factor pathway inhibitor (TFPI) is the major physiological inhibitor of TF. This study analyzes the role of TF on thrombogenicity of disrupted human atherosclerotic plaques and the therapeutic possibilities of its specific inhibition. METHODS AND RESULTS: Human atherosclerotic and normal arterial segments were exposed to heparinized blood at flow conditions modeling medium-grade coronary stenosis in the Badimon perfusion chamber. The antithrombotic effects of the specific inhibition of plaque TF was assessed by reduction in the deposition of radiolabeled platelets and fibrin(ogen) and immunohistochemical analysis of perfused arteries. TF activity was inhibited by both recombinant TFPI and a polyclonal antibody against human TF. Human lipid-rich plaques were more thrombogenic than less advanced atherosclerotic plaques. Specific inhibition of TF activity reduced plaque thrombogenicity, inhibiting both platelet and fibrin(ogen) deposition (580 versus 194 plateletsx10(6)/cm2; P<0.01, and 652 versus 172x10(12) molecules of Fg/cm2; P<0.05, respectively) and thrombosis (immunohistochemistry). CONCLUSIONS: This study documents the key role of TF activity in acute arterial thrombosis after atherosclerotic plaque disruption and provides evidence of the benefit of blocking plaque TF activity. Therefore the inhibition of the TF pathway opens a new therapeutic strategy in the prevention of acute coronary thrombosis after plaque disruption.
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Atherosclerotic plaque rupture and resulting intracoronary thrombosis are thought to account for most acute coronary syndromes. These syndromes include unstable angina, non-Q-wave myocardial infarction (MI) and Q-wave MI. In addition, many cases of sudden cardiac death may be attributable to atherosclerotic plaque disruption and its immediate complications. Our understanding of the atherosclerotic process and the pathophysiology of plaque disruption has advanced remarkably. Despite these advances, event rates after acute coronary syndromes remain unacceptably high. This review will focus on the pathophysiology underlying atherosclerotic plaque development, the sequellae of coronary plaque rupture, and current therapies designed to treat the acute coronary syndromes. It is hoped that as our understanding of the atherosclerotic plaque improves, treatment strategies for the acute coronary syndromes will advance.
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The acute coronary syndromes, that include unstable angina, acute myocardial infarction, and many cases of sudden cardiac death, exact a considerable price on society in terms of mortality, morbidity, and health care costs. The coronary atherosclerotic lesion is often an indolent and progressive entity that can destabilize causing an acute syndrome with or without warning. The majority of acute coronary syndromes result from events such as rupture or disruption of the atherosclerotic plaque with intracoronary thrombosis and ischemia of the distal myocardium as a result. Advances in our understanding of the process underlying the acute coronary syndromes has allowed for the identification of targets and rational therapeutic strategies for the prevention and treatment of these syndromes. Many of these therapeutic strategies involve the reversal of prethrombotic forces that often coexist with coronary atherosclerosis. Even with recent advances in our approach to atherosclerosis, intracoronary thrombosis, and the resulting acute coronary syndromes, an unacceptably high event rate persists after these syndromes. Further advances in the prevention and treatment of coronary atherosclerosis and its thrombotic complications depends on a more thorough understanding of the biology of the atherosclerotic plaque and the factors which influence its stability.
Diseases of the thoracic aorta are serious conditions that require close observations. Impressive advances in imaging modalities such as magnetic resonance imaging, computed tomography sacs, and transesophageal echocardiography have aided diagnosis and provided insights into the pathogenesis and natural history of thoracic aortic aneurysms, dissection, and atherosclerosis. The current review highlights the etiology, epidemiology, and pathophysiology of these disorders and focuses on the diagnostic approach and suggested medical therapies in the current era.