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128ALBUQUERQUE, LC ET AL -Vulnerability of atherosclerotic carotid disease: from laboratory to operating room -Part 1 Braz J Cardiovasc Surg 2006; 21(2): 127-135 INTRODUCTION Cerebrovascular obstructive disease (COD) is currently a priority for public healthcare in developed countries, due to its significant prevalence in the adult population, the severity of ischemic events and the high potential to negatively affect productive life [l,2]. Almost 30% of all cases of strokes may be attributed to atherosclerotic disease of the carotid bifurcation, acute thrombotic mechanisms or more commonly to distal embolization [3,4].In spite of significant advances that occurred in the medicinal treatment of COD, carotid endarterectomy (CE) remains an important measure in the prophylaxis of strokes and the elective treatment in severe obstructive lesions, even when ipsilateral hemispherical symptoms are not present [5,6]. Although in the 1970s CE became the favorite method to treat strokes, only in the 1980s and 1990s, with the results of several clinical trials, the precise identification of subgroups of patients who really benefited from the surgical strategy was possible. These findings resulted in establishing the consensual indications for CE used today, based exclusively on the percentage of stenosis [7,8].However, the concept of vulnerability of atherosclerotic plaque, initially introduced for coronary artery obstructive disease, reveals that susceptible injuries are characterized by the presence of necrosis in the nucleus of the plaque, by locations with great lipid concentrations but little cellularized, by areas of intraplaque hemorrhage and by eccentric growth, a phenomenon denominated as positive remodeling [9,10]. Ischemic events are dependent on the rupture of the fibrous cover, allowing the thrombogenic content of the plaque to come in contact with the blood, and not on the degree of stenosis or the hemodynamic significance of the lesions [11,12].Evidence on the involvement of inflammatory mechanisms in atherosclerosis have contributed to changing of etiopathogenic paradigms, substituting the traditional model of progressive and concentric accumulation of lipids on the arterial wall for the concept that the inflammation plays a central role in the formation and progression of the atheroma.Part I of this review aims at analyzing recent studies and relevance related to the vulnerability of atherosclerotic disease of carotid arteries, expressed by its epidemiological, clinical and inflammatory aspects. In Part II currently used serum markers are discussed, as are histological aspects and diagnosis by imaging, related to the instability of carotid artery disease, together with possible therapeutic implications or possible changes of criteria related to the current indications for intervention. Epidemiological aspectsIn developed countries, strokes constitute the third commonest cause of death in the adult population and the greatest determinant of permanent invalidity [13]. The incidence has been calculated as f...