Intravascular coagulation in hyperlipidemia

Influence of lipid metabolism disorders on venous thrombosis risk

Background: To investigate the influence of lipid metabolism disorders on the risk of deep vein thrombosis. Methods: A total of 200 subjects participated in the study, 100 of whom experienced DVT with or without PTE, and 100 healthy subjects representing the control group. We classified patients and controls in terms of serum concentrations of chylomicrons, LDL, IDL, VLDL, and HDL particles, as those with or without hyperlipoproteinemia and in terms of serum Lp (a) lipoprotein levels, as those with hyperLp (a) lipoproteinemia (serum Lp (a) values >0.3 g/L) and those without hyperLp (a) lipoproteinemia (serum Lp (a) values <0.3 g/L). Based on the modified and supplemented Fredrickson classification, participants with verified existences of hyperlipoproteinemia were classified into subgroups based on the type of hyperlipoproteinemia. Unconditional logistic regression was used to calculate ORs with 95% CIS as a measure of the relative risks for venous thrombosis in participants with hyperlipoproteinemia compared with those without hyperlipoproteinemia. The analysis was adjusted for all potential confounders (age, sex, obesity) related to the functionality of the lipid metabolism, and at the same time, may have an impact on the risk of venous thrombosis. Results: The results of the comparison of the mean values of individual lipid status parameters between the patient group and the control group clearly indicate higher concentrations of total cholesterol (5.93 mmol/L vs. 5.52 mmol/L), total triglycerides (1.58 mmol/L vs. 1.50 mmol/L), and LDL-cholesterol (3.83 mmol/L vs. 3.44 mmol/L) in the patient group relative to the control group, with a statistically significant difference observed only in the case of LDL-cholesterol concentrations. We have found that type IIa hyperlipoproteinemia is associated with a nearly double increased risk for deep vein thrombosis (OR 1.99; Cl 1.01-3.90), while type IIb, IV, or hyperLp (a) lipoproteinemia did not influence the risk (OR 1.22; 95% Cl 0.79-1.84; OR 0.89; 95% Cl 0.52-1.54 OR 1.85; 95% CI 0.84-4.04). Conclusions: Hypercholesterolemia doubles the risk of deep vein thrombosis development.

Platelets and coagulation in patients with familial hypercholesterolemia (type IIa)

Seventeen subjects with hypercholesterolemia (type IIa) were compared with 11 normocholesterolemic family members (controls) with similar dietary habits. The type IIa subjects had a shorter bleeding time. Beta-thromboglobulin in plasma and thromboxane B2 and malondialdehyde released from platelets before and after stimulation with collagen or thrombin were similar. No differences in platelet sensitivity to adenosine diphosphate, thrombin or collagen were observed. Gel-filtered platelets from type IIa subjects had a tendency to spontaneous aggregation and lower procoagulant activity. Platelet sensitivity to prostacyclin was slightly higher in type IIa subjects. No differences in a series of coagulation parameters were observed between the groups. This study has shown some deviations from normal in platelets from subjects with familial hypercholesterolemia. These changes may contribute to the increased tendency to occlusive vascular diseases in such subjects.

Plasma prekallikrein, kallikrein inhibitors, kininogen and lipids during gemfibrozil treatment in type II dyslipidaemia

The effects of gemfibrozil on plasma prekallikrein, kallikrein inhibitors, kininogen and plasma lipids were investigated in 31 male subjects having either type IIA or IIB dyslipidaemia. During gemfibrozil use, plasma prekallikrein and kininogen were increased significantly while kallikrein inhibitors increased only slightly. Total cholesterol and triglycerides decreased while HDL cholesterol was increased. Changes in prekallikrein and HDL cholesterol were correlated, whereas no other significant correlations between changes in lipid and kinin parameters were seen. The observed changes in prekallikrein and kininogen possibly indicate a shift in the thrombo-haemorrhagic balance in favour for increased fibrinolysis. If so, the effects of gemfibrozil in prevention and management of atherosclerosis would not be solely due to correlation of the dyslipidaemia but also to protection against the accelerated coagulation tendency seen in type II dyslipidaemia.

Does statin usage reduce the risk of corticosteroid-related osteonecrosis in renal transplant population?

The relationship between corticosteroids and osteonecrosis is well known. Limited data suggest that statins modulate cholesterol metabolism and may protect against osteonecrosis. The authors analyzed their prospective renal transplant database to determine if statin usage reduces the incidence of corticosteroid-related osteonecrosis and identified 2,881 renal transplantation patients who met the entry criteria. Among 338 patients on statins, 15 (4.4%) developed osteonecrosis, versus 180 of 2,543 (7%) patients who were not on statins. Osteonecrosis-free survival was similar in patients with and without statin exposure.

The Nicolas Andry award. The pathogenesis and prevention of steroid-induced osteonecrosis

The effects of steroids on a cloned pluripotential cell from bone marrow stroma were examined in vitro in culture and in vivo after the cells were transfected with a traceable gene and transplanted into host mice. Bipedal chickens were treated with steroids to establish a model for osteonecrosis. The effects of a lipid lowering agent, lovastatin, on the prevention of steroid induced adipogenesis in vitro in cell culture, and on adipogenesis and osteonecrosis in vivo in chickens, were evaluated. On treatment with dexamethasone, cloned pluripotential cells began to differentiate into adipocytes and expressed a fat specific gene, whereas the expression of Type I collagen and osteocalcin messenger ribonucleic acid decreased. Addition of lovastatin in culture inhibited steroid induced fat gene expression and counteracted the inhibitory effect of steroids on osteoblastic gene expression. Cloned pluripotential cells were transduced with a traceable retrovirus vector encoding the beta-galactosidase and neomycin resistance genes. The transfected cells were administered to mice either by tail vein or by direct intramedullary injection. Half of the animals in each group were treated with steroids. Histologic sections showed the appearance of transplanted cells in the marrow. Analysis of marrow blowouts by flow cytometry revealed that steroid treatment produced adipogenesis in transplanted cells. Evidence of osteonecrosis was observed in steroid treated chickens, whereas sections from animals treated with steroids and lovastatin showed less adipogenesis and no bone death. The results indicate that steroid induced adipogenesis in the marrow may contribute to osteonecrosis and that lovastatin may be helpful in preventing the development of steroid induced osteonecrosis.

Hyperlipidemia in acute hemolysis

In 27 (78%) of 36 patients with massive hemolysis (defined as a fall in hematocrit of more than 12% within 12 h due to intravascular red cell destruction), hypertriglyceridemia (plasma triglycerides greater than 175 mg/dl) was present or appeared within two days after the hemolytic crisis. Eighteen subjects with triglycerides exceeding 300 mg/dl (peak 516 +/- 39 mg/dl) were further analyzed. The development of hyperlipidemia was independent of the etiology of hemolysis (microangiopathic hemolytic disease 7, toxicemia 3, parainfectious complications 3, autoimmune hemolysis 2, glucose-6-phosphate dehydrogenase deficiency 2). Factors known to increase plasma triglycerides, such as shock, infections, or pancreatitis, were present in only a few cases. Hemolysis-associated complications were activation of intravascular coagulation (16), coma (13), acute renal failure (13), and respiratory insufficiency (5), organ dysfunctions indicating diffuse microvascular injury. Plasma triglycerides fell within a few days if the cause of red cell destruction was eliminated. In 5 of the 8 patients presenting with triglycerides below 175 mg/dl, severe hepatic dysfunction was present. We conclude that hemolysis causes transient hyperlipidemia, either directly by red cell destruction or indirectly by inducing intravascular coagulation, and possibly due to both increased triglyceride synthesis and decreased catabolism.

The contact activation system: biochemistry and interactions of these surface-mediated defense reactions

This review is intended to be a critical state-of-the-art overview of the activation and inhibition of the proteins (factor XII, prekallikrein, high molecular weight kininogen, and factor XI) of the contact phase of coagulation. Specifically, this review will reconsider the concept of the reciprocal activation of the proteases of the contact phase of coagulation, factor XII, and prekallikrein, in light of much recent evidence indicating that factor XII, itself, autoactivates when associated with negatively charged surfaces. In addition, the mechanisms for amplification of activation of the proteins of the contact phase of coagulation will be discussed from the pivotal role of high molecular weight kininogen, or one of its altered forms, serving as a cofactor to order the activation of the zymogens it is associated with. The role and relative importance of each of the naturally occurring plasma protease inhibitors (C1-inhibitor, alpha-2-macroglobulin, alpha-1-antitrypsin, antithrombin III, and alpha-1-antiplasmin) will be assessed as they relate to the dampening of contact phase activation. Finally, the contact phase of coagulation activation will be discussed not only as a plasma proteolytic mechanism, but also as it interacts with platelets.

Coronary artery disease and haemostatic variables in heterozygous familial hypercholesterolaemia

Haemostatic variables were measured in 61 patients with heterozygous familial hypercholesterolaemia, 32 of whom had evidence of coronary heart disease. Age adjusted mean concentrations of plasma fibrinogen and factor VIII were significantly higher in these patients than in the 29 patients without coronary heart disease, but there were no significant differences in serum lipid concentrations between the two groups. Comparisons in 30 patients taking and not taking lipid lowering drugs showed lower values for low density lipoprotein cholesterol, high density lipoprotein cholesterol and antithrombin III, and a higher high density lipoprotein ratio while receiving treatment. The results suggest that hypercoagulability may play a role in the pathogenesis of coronary heart disease in patients with familial hypercholesterolaemia.

Assay of factor VII activity by two techniques: evidence for increased conversion of VII to alpha VIIa in hyperlipidaemia, with possible implications for ischaemic heart disease

Factor VII was assayed in healthy adults and pregnant women by a coagulation method (VIIc) and a procedure (VIIt) based upon activation of factor X. Although VIIc and VIIt were highly correlated (r 0.8) they apparently measured different aspects of VII activity. This difference was related to plasma lipid concentrations. Plasma VIIc showed independent positive associations in vivo with VIIt, cholesterol and triglyceride concentrations, but was unaffected by in vitro adjustment of plasma lipoprotein concentrations. The difference between assays might be due to differing reactivities of VII. The VIIc assay measures VII in its in vivo proportions as the single-chain protein and fully active double-chain form (alpha VIIa). In VIIt, all VII is converted to alpha VIIa before measurement. Thus an increase in VIIc but not VIIt with increasing lipid concentrations reflects an increased proportion of VII as alpha VIIa, possibly secondary to activation of the contact system. This effect may explain at least part of the increased VIIc and normal VIIt in pregnancy, and the increased VIIc of hyperlipidaemias in general. The relative values of VIIc and VIIt are proposed as a measure of flux within the coagulation system, and as a measure of coagulability in hyperlipidaemia and other states.

Treatment by plasma exchange of a patient with hyperlipidemia and diabetic ketoacidosis with lesional pulmonary edema and acute pancreatitis

The authors report a case of severe hypertriglyceridemia (148.5 mmol/l) in a 27-year-old woman admitted for coma of unknown origin. Initial investigations revealed ketoacidosis, pancreatitis and noncardiogenic pulmonary edema. The diabetes was unknown. Ketoacidosis was rapidly controlled. The hypertriglyceridemia was corrected by one course of plasma exchange (4,400 ml) during which the patient returned to consciousness. The patient recovered without any sequelae. Only 2 similar cases, treated by plasma exchange, have been reported in the literature until now.

Plasma lipoprotein induction and suppression of the generation of cellular procoagulant activity in vitro: two procoagulant activities are produced by peripheral blood mononuclear cells

In the process of analyzing the effects of lipoproteins on functions of lymphoid cells, it was observed that physiological concentrations of isolated human plasma lipoproteins possess varying capacities to rapidly enhance the expression of procoagulant activity of human peripheral blood mononuclear cells in vitro. In a strict dose-dependent fashion, very low density lipoprotein, intermediate density lipoprotein, and high density lipoprotein enhanced both the surface expression by viable cells and the total cellular content of procoagulant activity during a 6-h incubation. Very low density lipoprotein induced a maximal 6.7-fold increase in the expression of a thromboplastin activity, which was consistent with tissue factor, in that it was dependent on Factors VII, X, and II. Both intermediate density lipoprotein and high density lipoprotein induced approximately a 12-fold increase of a different procoagulant activity which appears to be a direct prothrombin activator. This prothrombinase was calcium dependent and was inhibited by 2.5 mM diisopropylfluorophosphate, but was not neutralized by anti-Factor X antibodies or by inhibitors of Factor Xa. In contrast to the other lipoprotein density classes, low density lipoprotein did not stimulate procoagulant activity, but instead actively suppressed the generation of the two procoagulant activities induced by the stimulatory lipoproteins. Suppression by low density lipoprotein was clearly evident at molar ratios of low density lipoprotein to stimulatory lipoproteins of 1:3 or less. Reconstitution of all lipoproteins to physiological concentrations was not stimulatory as a consequence of the suppressive effects of low density lipoprotein. These data indicate that isolated plasma lipoproteins are capable of regulating the expression of two different procoagulant activities of peripheral blood mononuclear cells in vitro. The possibility that these interactions may be implicated in the association between certain types of hyperlipoproteinemias and thromboembolic disease merits study.

Normal levels of fibrinopeptide A in patients with primary hyperlipidemia

Fibrinopeptide A (FPA) levels were measured in a group of 130 controls and patients with various types of primary hyperlipidemia to investigate whether an increased steady state level of thrombin activity is present in hyperlipidemic patients. In a subset of 56 subjects, levels of clotting factors II, VII, and X were measured as well. FPA levels in hyperlipidemic patients were not significantly different from those of control subjects. Furthermore, on multiple regression analysis, no significant relationships were found between FPA levels and the concentrations of serum cholesterol or triglyceride, or log triglyceride levels. Statistically significant relationships were found between all three clotting factor levels and triglyceride concentration. The correlation coefficients for these relationships, however, were low, so that the correlations are of questionable pathophysiological significance. A weak relationship also was found between the plasma levels of cholesterol and of factor II. Thus, although small increases in various clotting factors may be found in patients with hyperlipidemia, plasma FPA levels are normal. These data indicate that hyperlipidemia is not associated with a steady state of increased thrombin activity in vivo in humans.

Effect of clofibrate on intravascular coagulation in hyperlipoproteinemia

Intravascular coagulation (IVC) was evaluated in 19 patients with type II and 11 with type IV hyperlipoproteinemia before and after clofibrate therapy by measurements of soluble fibrin complexes (SFC) in plasma; fibrinolysis was estimated by quantitation of fibrin (ogen) degradation products in serum. Untreated type II and type IV patients had increased SFC (P less than 0.01). The former also had activation of the intrinsic coagulation pathway as evidenced by decreased plasma prekallikrein (P less than 0.001), kallikrein inhibitors (P less than 0.001), and factor XII (P less than 0.02). Although clofibrate treatment of the type II patients did not change plasma lipids, it decreased intravascular coagulation, apparently via decreased factor XII activation and stimulation of fibrinolysis. In contrast, treated type IV patients had unchanged SFC and FDP levels, despite decreased plasma triglycerides (P less than 0.01). Clofibrate-induced changes in blood coagulation are independent of lipid-lowering. Clofibrate therapy decreases intravascular coagulation in type II patients and may help to prevent thromboembolic sequelae.

Therapy of the hyperlipidemias

Although the diagnosis of hyperlipidemia is somewhat arbitrary, in that the upper limits of normal are not universally agreed upon, it is clear that the risk of atherosclerosis increases with plasma cholesterol concentration; it may also increase in hyperglyceridemia. We take 220 mg/100 ml as the upper limit of normal for plasma cholesterol and 140 mg/100 ml as the upper limit for triglycerides. Treatment of hyperlipidemia is aimed at reducing the risk of atherosclerosis or arresting its course. Alteration of diet is the first step. If maximal diet therapy does not lower plasma lipids to acceptable levels, drug therapy is added. The decision to treat hyperlipidemia with drugs should be based on a careful weighing of risk vs. benefit for each patient. Because of the rapid change in our knowledge of both the risks and the benefits of therapy, that decision must be reviewed and updated at regular intervals.