Rheological aspects of cerebrovascular disease

Fibrinogen and LDL Influence on Blood Viscosity and Outcome of Acute Ischemic Stroke Patients in Indonesia

BACKGROUND

To assess the role of risk factors of metabolic syndrome on blood viscosity and the prognosis of acute ischemic stroke in Indonesia based on the National Institute of Health Stroke Scale (NIHSS) and modified Rankin Scale (mRS).

METHODS

This study included 135 patients with acute ischemic stroke. Patients underwent measurements of viscosity and risk factor assessment. Analysis was performed to assess the role of these risk factors for blood viscosity and outcomes of acute ischemic stroke with NIHSS and mRS as indicators. NIHSS was assessed at <3 days after onset and 7 days after onset, while mRS was assessed 1 month post treatment. Bivariate analysis was performed using chi-square test, and variables with p < 0.25 were further analyzed in multivariate analysis using logistic regression.

RESULTS

Factors affecting blood viscosity are fibrinogen, low-density lipoprotein (LDL), and hematocrit. Factors affecting NIHSS and mRS are fibrinogen and LDL.

CONCLUSION

Fibrinogen and LDL affect the viscosity of blood and outcomes in acute ischemic stroke patients, so it is necessary to treat in the primary and secondary prevention of ischemic stroke.

Effect of parenteral or oral vinpocetine on the hemorheological parameters of patients with chronic cerebrovascular diseases

INTRODUCTION

Hemorheological factors play an important role in the pathomechanism of ischemic cerebrovascular disorders. Abnormal rheological conditions in patients with chronic cerebrovascular disease predispose for recurrent strokes. Vinpocetine (VP), a synthetic ethyl esther of apovincamine, has successfully been used in the treatment of cerebrovascular diseases, in part because of its favourable rheological effects.

PATIENTS AND METHODS

The study investigates the hemorheological changes in 40 patients in the chronic stage of ischemic cardiovascular disease after administration of vinpocetine. All patients received a high dose of intravenous VP in doses gradually increased to l mg/kg/day. In addition, 20 patients (mean age: 61+/-8 years) received 30 mg VP orally for 3 months. The other 20 patients (mean age: 59+/-6 years), who received placebo tablets, served as controls. Hemorheological parameters (hematocrit, plasma fibrinogen, whole blood viscosity, red blood cell aggregation and deformability) were evaluated at 1 and 3 months.

RESULTS

The high-dose parenteral VP significantly decreased red blood cell aggregation, plasma and whole blood viscosity (p < 0.05) compared to the initial values. In patients with additional oral treatment, plasma and whole blood viscosities were significantly lower compared to the placebo patients at 3 months (p < 0.05).

CONCLUSION

Our results confirmed the beneficial rheological effects of high-dose parenteral VP (partially caused by hemodilution) observed previously, and also warrant its long-term oral admission to maintain the beneficial rheological changes.

Correction of the high blood viscosity syndrome by a mixture of Diquertin and Ascorbic Acid in vitro and in vivo

Diquertin was shown to diminish blood viscosity, to decrease the aggregation of erythrocytes, and to increase their deformability using a model of the high blood viscosity syndrome in vitro. A mixture of Diquertin with Ascorbic Acid was more effective in improving rheological indicators of blood, then either Diquertin or Tanakan. On a model of chronic brain ischemia, which is accompanied by significant deterioration of the rheological properties of blood, it was shown that a therapy with a mixture of Diquertin and Ascorbic Acid decreases the expression of the high blood viscosity syndrome.

Nisoldipine improves the impaired erythrocyte deformability correlating with elevated intracellular free calcium-ion concentration and poor glycaemic control in NIDDM

AIMS

To explore the mechanisms underlying the impaired erythrocyte deformability (RBC-df) in diabetic patients, the relationship between erythrocyte intracellular free calcium-ion concentration ([Ca2+]i) and RBC-df, and the effects of Ca2+-channel blocker on [Ca2+]i and RBC-df were evaluated.

METHODS

Forty-eight patients with NIDDM and 24 control subjects were enrolled in this study. [Ca2+]i was determined using fura-2, and RBC-df by filtration method expressed as Deformability Index (DI). Erythrocytes were treated with nisoldipine to evaluate the effects of a Ca2+-channel blocker.

RESULTS

[Ca2+]i was significantly higher (82.6 (78.0-87.2) vs 76.6 (74.3-81.2) nmol lRBC-1, P<0.001), and DI was significantly lower (0. 14 (0.09-0.28) vs 0.22 (0.16-0.28), P<0.01) in NIDDM than in controls. There was a significant correlation between HbA1c and [Ca2+]i (r=0.38, P<0.01), between HbA1c and DI (r=-0.51, P<0.01), and between [Ca2+]i and DI (r=-0.42, P<0.01). Stepwise multiple regression analysis revealed HbA1c and [Ca2+]i as independent determinants for the impaired RBC-df. Nisoldipine treatment in vitro significantly decreased [Ca2+]i, and significantly improved RBC-df.

CONCLUSIONS

These data indicate that the impaired RBC-df in NIDDM may at least partly be attributed to the elevated [Ca2+]i and poor glycaemic control. In addition, favorable effects of a Ca2+-channel blocker on both [Ca2+]i and RBC-df have been demonstrated.

Effects of different antihypertensive drugs on plasma fibrinogen in hypertensive patients

1. In order to evaluate whether treatment with different antihypertensive drugs would affect plasma fibrinogen levels, 118 mild to moderate essential hypertensive subjects, all males, aged 18 to 65 years, were randomly treated with amlodipine 10 mg, atenolol 100 mg, hydrochlorothiazide 25 mg or lisinopril 20 mg, all given once daily for 8 weeks. 2. Before and after 8 weeks' treatment, blood pressure (BP), heart rate (HR), fibrinogen, total cholesterol (TC), HDL-C, LDL-C, triglycerides (TG), plasma glucose, plasma uric acid, serum creatinine and serum potassium were evaluated. 3. All four medications significantly reduced BP values, although the BP lowering effect of lisinopril, amlodipine and atenolol was significantly greater compared with that of hydrochlorothiazide. 4. Plasma fibrinogen levels were unaffected by atenolol, hydrochlorothiazide and amlodipine, whereas they were significantly decreased by lisinopril (-11.2%, P = 0.002). This fibrinogen lowering effect was more evident in smokers (-17.7%) than in non smokers (-7.4%). 5. Atenolol and amlodipine did not significantly affect plasma lipids, hydrochlorothiazide increased TC, LDL-C and TG and reduced HDL-C; lisinopril increased HDL-C and decreased TC and LDL-C. 6. Hydrochlorothiazide increased plasma glucose and uric acid concentrations, which were unaffected by the other drugs. The diuretic also reduced serum potassium. 7. The results of this study indicate that lisinopril reduces levels of plasma fibrinogen and confirm that different antihypertensive drugs may elicit different metabolic effects, which may variously influence the overall risk profile of the hypertensive patients.

Fibrinogen and lipid concentrations as risk factors for transient ischaemic attacks and minor ischaemic strokes

OBJECTIVES

To determine whether fibrinogen and lipid concentrations are risk factors for ischaemic stroke.

DESIGN

Case-control study with a population based comparison within the overall study.

SETTING

Oxfordshire community stroke project and a neurology clinic.

SUBJECTS

105 patients who had a transient ischaemic attack or minor ischaemic stroke and 352 randomly chosen controls matched for age and sex from the same general practitioners as the incident cases. 52 controls were ineligible or refused interview. 104 cases and 241 controls gave blood samples for analysis.

MAIN OUTCOME MEASURES

Response to structured questionnaire, height, weight, blood pressure, and serum concentrations of fibrinogen and lipids.

RESULTS

Adjusted for other variables, odds ratios of ischaemic stroke were 1.78 (95% confidence interval 0.91 to 3.48; p = 0.09) [corrected] for fibrinogen concentrations greater than 3.6 g/l; 1.73 (0.90 to 3.29; p = 0.09) [corrected] for total cholesterol concentrations greater than 6.0 mmol/l; 1.34 (0.69 to 2.61; p greater than 0.4) for low density lipoprotein cholesterol concentrations greater than 3.5 mmol/l; and 0.32 (0.15 to 0.69; p = 0.002) for high density lipoprotein cholesterol concentration greater than 1.2 mmol/l. Similar results emerged comparing only community derived cases with transient ischaemic attacks and controls. The effects of fibrinogen, total cholesterol, and high density lipoprotein cholesterol were significant in a test of trend after adjusting for all other variables in the study (chi 2 = 4.14, p less than 0.05; chi 2 = 4.31, p less than 0.05, and chi 2 = 12.15, p greater than 0.001, respectively). History of ischaemic heart disease and hypertension were the only other variables that showed significance, though both lost significance after adjustment (2.06, p = 0.08 and 1.53, p = 0.2, respectively).

CONCLUSIONS

Fibrinogen and lipids are important risk factors for ischaemic stroke. The pattern of changes mirrors that found in ischaemic heart disease.

Isovolemic hemodilution in experimental focal cerebral ischemia. Part 1: Effects on hemodynamics, hemorheology, and intracranial pressure

A total of 76 splenectomized dogs were entered in a study of the value and effects of isovolemic hemodilution. Of these, seven were not included in the analysis because of technical errors. Of the remaining 69 dogs, 35 were treated with hemodilution; 28 were subjected to a 6-hour period of temporary occlusion of the distal internal carotid artery and the proximal middle cerebral artery, and seven underwent a sham operation only, with arterial manipulation but no occlusion. The other 34 dogs were not subjected to hemodilution; 26 of these underwent temporary arterial occlusion and eight had a sham operation only. In each group the animals were about equally divided into 1) an acute protocol with regional cerebral blood flow measurements by a radioactive microsphere technique and sacrifice at the end of the acute experiment, and 2) a chronic protocol with survival for 1 week to permit daily neurological assessment and final histopathological examination but without blood flow measurements. Isovolemic hemodilution was performed about 1 hour after the arterial occlusion or sham operation and was accomplished by phlebotomy and infusions of low molecular weight dextran to bring the hematocrit to a level of 30% to 32%. This treatment resulted in a very significant reduction in viscosity and fibrinogen levels. The decrease in hematocrit lasted throughout the week in the animals in the chronic protocol. The decrease in viscosity correlated almost linearly with the decrease in hematocrit. There was a slight decrease in systemic arterial pressure with hemodilution but there were no significant changes in central venous pressure or in pulmonary arterial or wedge pressure. There was a slight decrease in cardiac index in both the hemodilution and control groups, which may have been due to the effects of barbiturate anesthesia. There was a slight increase in the measured blood volume in both groups, which was probably artifactual and related to the method of calculation. Intracranial pressure increased significantly with time in all animals subjected to arterial occlusion, but this increase was less severe in the hemodilution group. There was no significant change in intracranial pressure in sham-operated animals, whether hemodiluted or not. The results of cerebral blood flow measurements, assessment of neurological conditions, and measurement of infarct size are given in Part 2 of this report.

Effects of propentofylline (HWA 285) on laser-induced thrombus formation in healthy and diseased rat mesenteric arterioles

The antithrombotic effects of the xanthine derivative propentofylline (HWA 285) were investigated in the laser-induced thrombus model in healthy and diseased rat mesenteric arterioles. Laser-induced platelet thrombi were documented by the help of an intravital microscope and a video system. The statistical comparison of drug-treated and untreated animals, in respect to the number of laser shots necessary to induce a defined thrombus, served as a quantitative measure for a potential antithrombotic drug effect. Propentofylline and acetylsalicylic acid, in single dosages of 10 and 30 mg/kg orally, significantly increased the number of laser shots required to produce a defined thrombus. Moreover, the drug decreased the laser-induced thrombus formation in a chronic experiment in adjuvant arthritic rats. After oral administration of 30 mg/kg for 21 days, propentofylline and pentoxifylline reduced significantly the thrombus formation, whereas acetylsalicylic acid exerted no effect.