Hyper coagulability and thrombosis

Abstract

Role of antithrombin III (ATIII) and blood viscosity in development of thrombosis are investigated. A moderate decrease in levels of plasma ATIII before and after the development of acute myocardial infarction was observed. In cases of acute myocardial infarction, in whom concentrations of ATIII in plasma decreased markedly, thromboembolic episodes frequently developed. Levels of ATIII in plasma occasionally increased following oral anticoagulant therapy. From these results, it is suggested that ATIII in blood may be consumed in hypercoagulable states by reacting activated procoagulants formed in circulating blood. In observations in 437 autopsied cases with mean age of 77, acute myocardial infarction seldom developed when sclerotic changes of coronary arteries remained mild. Incidence of myocardial infarction in cases with severe coronary sclerosis increased with elevation of hematocrits, measured on admission. It is suggested that, in cases of myocardial infarction with slight arteriosclerotic changes or very low hematocrit values, possibility of complication of DIC (disseminated intravascular coagulation) should be considered. Most remarkable decrease in levels of ATIII was observed in cases of DIC. Necessity of replacement therapy of ATIII is suggested, because of inefficacy of heparin therapy in patients with DIC, in whom levels of ATIII markedly decreased. Concentrations of ATIII in plasma were lower in younger females but higher in elderly ones than males with corresponding ages. Blood viscosity and hematocrit values were lower in women than in men in all decades of life over age 20. In elderly women, these may act beneficially for protecting them from thrombosis.