Hemorheological Factors Research Articles

Influence of fibrinogen and haemorheological factors on endothelial function in healthy women

Influence of fibrinogen and haemorheological factors on endothelial function in healthy women

Effects of Choto-san on hemorheological factors and vascular function in stroke-prone spontaneously hypertensive rats.

Choto-san is a formula used for the treatment of headache and vertigo. Recently it has often also been used for hypertension and dementia. One of the mechanisms involved is thought to be the improvement of blood circulation, but the details are still unclear. In this study, the effect of Chotosan was studied on nitric oxide (NO) function, hemorheological factors and endothelial function in stroke-prone spontaneously hypertensive rats (SHR-SP). Rats were given Choto-san in drinking water for eight weeks. Body weight, blood pressure, serum NO2-/NO3-, lipid peroxides, blood viscosity, erythrocyte deformability and endothelium-dependent/-independent relaxation were measured. The results indicated that Choto-san caused a decrease in blood pressure and an increase in erythrocyte deformability and NO function. Blood viscosity was not changed. Furthermore, endothelium-dependent relaxation by acetylcholine was significantly increased as compared to control. In this study, it was supposed that Choto-san had a protective effect on the endothelium. SHR-SP is a useful model for human brain stroke, and Choto-san showed a protective effect against cerebral vascular injury in the susceptible rat.

Value or desirability of hemorheological-hemostatic parameter changes as endpoints in blood lipid-regulating trials.

High levels of plasma lipids have been recognized as a major risk factor in the development and progression of atherosclerosis, and to influence hemorheological factors that may predispose to thrombotic complications. Lipid-lowering interventions have been associated with a significant reduction of morbidity and mortality. Several mechanisms have been postulated for the observed clinical effect. Serum lipid-regulating therapies may reduce cardiovascular risk not only by altering the arterial wall, improving disturbed endothelial function, atherogenesis and plaque stability, but also through their antithrombogenic effects and influence on blood flow properties associated with hyperlipidemia. In this article, we will review the recent literature and discuss the value of hemorheological-hemostatic findings as surrogate endpoints for clinical trials in dyslipidemic patients.

Correlation between carotid intima-media thickness and hematocrit and hemoglobin values in renal transplant recipients.

Cardiovascular diseases are the main causes of morbidity and mortality in kidney transplant recipients. Blood viscosity plays an important role in the development of arteriosclerosis in the general population. Since hematocrit (Ht) and hemoglobin (Hb) values are determinants of blood viscosity, we decided to perform a study to check the possible relevance between these hemorheological factors and carotid intima-media thickness (IMT) in renal transplant recipients. The study was performed on 33 clinically stable renal transplant recipients and 19 healthy persons. All subjects underwent ultrasonographic measurements of IMT. Analyzed clinical parameters included: age, sex, body mass index (BMI), mean arterial blood pressure (MAP), pulse pressure (PP) time from renal transplantation, and time on dialysis. The following biochemical parameters were assessed: Hb, Ht, fibrinogen (Fbg), and homocysteine (tHcy) concentrations (estimated by enzyme immunoassay). The two analyzed groups did not differ in respect to age and BMI. Mean concentrations of Hb and Ht values were lower in the patients group. Mean carotid IMT, Fbg, tHcy, MAP, and PP were significantly higher in the renal transplant recipients group when compared to the control group. IMT was positively correlated with age (r=0.55; p=0.001), Hb (r=0.36; p=0.04), Ht (r=0.34; p<0.05), PP (r=0.35; p<0.05), Fbg (r=0.4; p=0.02), and time on dialysis prior to transplantation (r=0.50; p=0.003) in the patients group. Multiple regression analysis in renal transplant recipients showed that the IMT was independently related to age, Hb or Ht values, and Fbg. The results for the first time show positive association between IMT and Ht and Hb values in renal transplant recipients. The results may implicate the role of these rheological factors in progression and acceleration of arterial remodeling in renal transplant recipients.

Clinical utility of the platelet function analyzer (PFA-100) in cardiothoracic procedures involving extracorporeal circulation

J Thorac Cardiovasc Surg 2001;122:190-1

C. Specific effects of Different Hemorheological Factors on Blood Flow Resistance in Microvessels

C. Specific effects of Different Hemorheological Factors on Blood Flow Resistance in Microvessels

C. Specific effects of Different Hemorheological Factors on Blood Flow Resistance in Microvessels

C. Specific effects of Different Hemorheological Factors on Blood Flow Resistance in Microvessels

Algunos factores hemorreológicos en pacientes con enfermedad cerebrovascular isquémica

To study hemorheological factors in patients with ischemic cerebrovascular disease (not secondary to embolic cardiopathy). We assessed 40 patients with an average age of 64.5 years; 26 had cerebral infarcts due to alterations in major blood vessels and 14 had lacunar infarcts. Forty persons with no cerebrovascular disease acted as controls. The hematological studies were done between three weeks and six months after the initial ictus. Blood viscosity and plasma fibrinogen concentrations were significantly higher in the patients than in the controls. However, hematocrit values were similar in all three groups studied. With regard to the hematocrit, fibrinogen levels and blood viscosity, no differences were seen between the group with damage to the great vessels and those with lacunar infarcts.

Design and development of a new ultrasonic doppler technique for estimation of the aggregation of red blood cells

Aggregation of red blood cells (RBCs) is one of the principal hemorheological factors which plays an important role in capillary circulation. In order to study the RBC's aggregation, an ultrasound Doppler in-vitro technique, using pulsed wave monoelement pencil 4 MHz probes, has been designed. An hydraulic pump system has been implemented, establishing a laminar blood flow profile into a rectangular cross-section plexiglass tube. Adding dextrans to blood samples, red blood cells aggregation has been achieved and observed for various hematocrit values. Both the emitted and the backscattered signals, were driven to a system containing a multi-channel digital oscilloscope – of high sampling rate and processing capabilities – and a powerful PC with a high acquisition A/D card and special control software. Quantitative detection and measurement of the aggregation phenomenon can be achieved according to the experimental conditions and parameters used.

Acute hemoconcentration during psychological stress: Assessment of hemorheologic factors

In this study, we examined the effects of acute psychological stress on hemorheology and hemoconcentration in humans and the associations between stress-induced cardiovascular reactivity and hemorheological changes. Stress-induced changes in hemorheology and hemorheological changes were assessed by measuring plasma viscosity, calculated plasma volume, and total plasma protein. Cardiovascular, hemorheologic, and hematologic variables were assessed in 29 healthy men during a 30-min baseline period and a 5-min speech task. Results indicated that the speech task produced a significant increase in plasma viscosity and total plasma protein and a significant decrease in calculated plasma volume. Significant correlations were observed between changes in blood pressure and heart rate and changes in plasma viscosity, total plasma protein, and calculated plasma volume. These results provide direct evidence that acute psychological stress can produce significant changes in hemorheology and hemoconcentration. The most likely mechanism for the stress-induced hemoconcentration effect is a fluid shift from the vascular to the interstitial spaces through increased blood pressure.

Smoking, hemorheologic factors, and progression of peripheral arterial disease in patients with claudication

Purpose: The purpose of the current study was to determine whether hemostatic and rheologic factors are associated with the deterioration of peripheral arterial disease in patients with intermittent claudication and the influence of smoking and severity of underlying disease on these relationships. Methods: We conducted a prospective cohort study with a 6-year follow-up period of a consecutive series of 607 patients with uncomplicated intermittent claudication. The study setting was the Peripheral Vascular Clinic, Royal Infirmary of Edinburgh. The main outcome measures were peripheral vascular intervention or onset of severe chronic leg ischemia (rest pain, ulceration, gangrene). Results: A total of 210 patients died during follow-up. Two hundred three patients did not have a vascular event or deterioration of limb ischemia, 45 patients underwent a peripheral vascular intervention, and 64 progressed to severe chronic leg ischemia. Median levels (interquartile ranges) of whole blood viscosity were significantly higher in the vascular intervention group (3.75 mPa/sec; range, 3.38 to 4.13 mPa/sec) than in those who did not deteriorate 3.48 mPa/sec; range, 3.06 to 3.83 mPa/sec) ( p ≤ 0.05), and plasma von Willebrand factor was higher in those with severe chronic leg ischemia (154.0 IU/dl; range, 122.0 to 187.0 IU/dl) than in those who did not deteriorate (131.0 IU/dl; range, 106.0 to 165.0 IU/dl) ( p ≤ 0.01). After adjustment for age, sex, cigarette smoking, and ankle brachial pressure index, the levels of plasma fibrinogen and blood and plasma viscosities were each associated with an increased risk of vascular intervention (all p ≤ 0.05). There were no significant associations between any of the hemorheologic factors and the risk of severe chronic leg ischemia on multivariate analyses. Conclusion: Elevations in rheologic factors may have important effects on further reduction of blood flow in the legs of patients with claudication and promote worsening ischemia and clinical progression of symptoms.(J Vasc Surg 1998;28:129-35.)

Blood viscosity and elevated carotid intima-media thickness in men and women: the Edinburgh Artery Study.

Several hemostatic and rheological factors have been associated with incident cardiovascular events. However, there have been no reports on the relationship of rheological factors with early atherosclerosis and very few on hemostatic factors. We therefore studied the relationship between these factors and carotid intima-media thickness (IMT). The Edinburgh Artery Study measured fibrinogen, tissue plasminogen activator (tPA), fibrin D-dimer, von Willebrand factor (vWF), blood and plasma viscosities, and hematocrit as part of its baseline examination during 1988-1989. At the 5-year follow-up, valid measurements of IMT had been recorded in 1106 men and women 60 to 80 years old. In men, blood viscosity (P< or =.001) and its major determinants, plasma viscosity, fibrinogen (both P< or =.01), and hematocrit (P< or =.05), were all linearly related to IMT. Furthermore, blood viscosity, fibrinogen (both P< or =.01), and plasma viscosity (P< or =.05) remained significantly associated on multivariate analysis. Correcting blood viscosity to a standard hematocrit of 45% had little effect on its association. In men, there was a significantly increased risk of having an IMT above versus below the upper quartile of its distribution (1.05 mm) for SD increases in blood viscosity (P< or =.01), fibrinogen, corrected blood viscosity, and plasma viscosity (all P< or =.05). With the exception of plasma viscosity, these risks were unaffected by adjustment for other common cardiovascular risk factors. No significant associations were found between any of the hemorheological factors and IMT in women or for tPA, fibrin D-dimer, or vWF in either sex. These findings suggest that in men, blood viscosity and its major determinants are associated not only with incident cardiovascular events but also with the early stages of atherosclerosis. This may be one explanation for the link between rheological factors and events.

Abnormalities in haemorheological factors and lipoprotein (a) in retinal vascular occlusion: implications for increased vascular risk.

The pathogenesis of retinal vascular occlusion (RVO), which includes patients with retinal vein or artery occlusions, may be associated with abnormalities of rheology and coagulation. These abnormalities have previously been linked with an increased risk of cardiovascular disease and stroke. To investigate changes in haemorheological factors (plasma viscosity, haematocrit, haemoglobin, white cell count (WCC), plasma fibrinogen (CLAUSS), soluble adhesion molecule P-selectin (associated with platelet activity and atherosclerosis; ELISA), von Willebrand factor (vWf, an index of endothelial dysfunction; ELISA), fibrin D-dimer (ELISA), lipoprotein(a) (Lp(a), immunoturbidometric assay) and serum lipids, we conducted a cross-sectional case-controlled study of 49 patients (37 men; mean age 66.9 years, SD 12.1 years) with RVO; 34 patients had retinal vein occlusion, whilst 15 had retinal artery occlusion. Their results were compared with those in 36 healthy controls (21 men; mean age 63.7 years, SD 14.8 years). Patients with retinal vein occlusion and retinal artery occlusion had higher systolic and diastolic blood pressures compared with controls (both p < 0.0001). These patients also had significantly elevated levels of plasma viscosity, haematocrit, haemoglobin, plasma fibrinogen, PAI, fibrin D-dimer and serum Lp(a) compared with controls. Apart from a reduction in blood pressure, there were no significant differences in the indices measured in patients with retinal vein occlusion when levels measured during their first and second visits were compared. In patients with retinal artery occlusion mean plasma PAI levels were significantly lower at visit 2 compared with visit 1. Plasma viscosity was significantly correlated with fibrinogen (r = 0.63, p < 0.001), systolic blood pressure (r = 0.33, p = 0.03) and cholesterol (r = 0.32, p = 0.04), while P-selectin was correlated with Lp(a) levels (r = 0.38, p = 0.03). This study suggests that abnormalities in haemorheological factors, fibrinogen and Lp(a) are present in patients with retinal vein occlusion and retinal artery occlusion. These abnormalities appear to persist even at follow-up examination 4-6 weeks later. Abnormalities in haemorheological factors, fibrinogen and Lp(a) may have a role in the pathogenesis of retinal vein occlusion and retinal artery occlusion, perhaps acting synergistically with clinical risk factors such as blood pressure. In addition, as haemorheological factors, fibrinogen and Lp(a) are associated with vascular disease, these findings in patients with RVO may potentially contribute to an increased risk of cardiovascular disease and stroke.

Relation of Endothelium, Thrombogenesis, and Hemorheology in Systemic Hypertension to Ethnicity and Left Ventricular Hypertrophy

Although the arterial tree is exposed to increased pressure in hypertensive patients, paradoxically, the complications of hypertension (heart attacks, stroke) are mainly thrombotic rather than hemorrhagic. Patients with left ventricular (LV) hypertrophy are at high risk of the complications of hypertension. We performed a cross-sectional study of 178 patients attending a hypertension clinic in a city center teaching hospital, and measured plasma levels of the soluble adhesion molecule P-selectin (associated with platelet activity/function and atherosclerosis), the von Willebrand factor (vWf; a marker of endothelial dysfunction), fibrin D-dimer (an index of thrombogenesis), plasminogen activator inhibitor (PAI, an index of fibrinolysis), lipoprotein(a) (Lp(a), associated with thrombogenesis and atherogenesis) and hemorheological indexes (fibrinogen, hematocrit, plasma viscosity, hemoglobin) in patients with essential hypertension, in whom the LV mass and LV mass index were determined using echocardiography. The 178 patients (86 men, mean age 54 ± 15 years) were compared with 47 normotensive healthy controls (aged 56 ± 20 years). Hypertensive patients had higher P-selectin, PAI, vWf, fibrin D-dimer, Lp(a), plasma fibrinogen, and plasma viscosity when compared with controls. Black hypertensive patients had higher Lp(a) levels and LV septal and posterior wall thickness on echocardiography, but lower plasma PAI levels. Patients with LV hypertrophy (defined as a LV mass index >134 g/m 2 in men or >110 g/m 2 in women) had higher plasma fibrinogen compared with those without LV hypertrophy. Systolic blood pressures were significantly correlated to age, plasma viscosity, plasma fibrinogen, and vWf. Diastolic blood pressures were significantly correlated with age and plasma fibrinogen. Fibrinogen levels were correlated with LV mass, LV mass index, left atrial size, plasma viscosity, and vWf. Fibrin D-dimer levels were significantly correlated with vWf and fibrinogen levels. Thus, hypertensive patients have high plasma fibrinogen levels, thrombogenesis, and impaired fibrinolysis (as indicated by high D-dimer and PAI levels, respectively), platelet activation (raised soluble P-selectin), and endothelial dysfunction (high vWF). The high plasma fibrinogen levels were related to blood pressures, LV mass index (and LV hypertrophy), and left atrial size. These abnormalities in hemorheologic factors and markers of thrombogenesis and endothelial function may act synergistically to increase the risk of thrombogenesis and atherosclerosis in hypertensive patients.

The role of rheological and haemostatic factors in hypertension.

Research into the pathogenesis of hypertension has, in the past, tended to concentrate on changes in vascular geometry, cardiac output and blood volume. However, patients with hypertension are known to be at an increased risk of both coronary heart disease and cerebrovascular disease; complications which are thrombotic in origin. Since rheological and haemostatic factors are known to be involved in thrombogenesis, their potential role in the pathogenesis of patients with hypertension has received increasing attention. The purposes of this review are to update previous reviews and to summarise the relationship between hypertension, its complications and treatment and a range of haemorheological factors.

Correction of erythrocyte shape abnormalities in familial hypercholesterolemia after LDL-apheresis: does it influence cerebral hemodynamics?

It is well known that red blood cells incubated in low-density lipoprotein (LDL)-rich medium show shape abnormalities that revert to normal after reincubation in normal plasma. Patients with homozygous familial hypercholesterolemia (HFH) have an increased percentage of abnormally-shaped erythrocytes (mostly stomatocytes, knisocytes, and crenated cells) compared to normocholesterolemic controls: 7.73+/-0.96 versus 3.52+/-0.52 (mean+/-SEM; P = 0.001). To confirm the role of high LDL concentration in inducing red cell shape abnormalities we determined the percentage of abnormally shaped erythrocytes in seven HFH patients 1 day after the procedure of LDL-apheresis with a 40% cholesterol decrease. A reduction in kniscocytes, stomatocytes, and crenated cells was observed in the patients treated by LDL-apheresis (P < 0.01). To investigate the possible benefit of a reduction in erythrocyte shape abnormality on cerebral hemodynamics, cerebral flow velocity, as evaluated by transcranial Doppler, was evaluated concomitantly and found to be remarkably increased after apheresis (P < 0.01). No significant change in hematocrit, plasma viscosity, blood viscosity, mean pressure, or cardiac output was detected, 1 day after apheresis. An inverse correlation was demonstrated (r = 0.55; P = 0.04) between changes in the percentage of knisocytes+stomatocytes +crenated cells and percent changes in middle cerebral artery peak systolic velocity. The correction of erythrocyte shape abnormalities after LDL-apheresis might be related to dramatic changes in plasma phospholipid concentration and proportion occurring after this procedure in HFH patients. The reduction of erythrocyte shape abnormalities could contribute, together with other hemorheological factors, to the improvement of cerebral hemodynamics after LDL-apheresis.

Effects of Defibrination on Hemorheology, Cerebral Blood Flow Velocity, and CO 2 Reactivity During Hypocapnia in Normal Subjects

Plasma fibrinogen is reported to be an independent risk factor for stroke and cardiovascular diseases. The effects of defibrination on hemorheology, middle cerebral artery (MCA) blood flow velocity, and CO2 reactivity during hypocapnia were evaluated in normal subjects. Twenty-five healthy subjects (mean age, 31.8 +/- 5.7 years) were included in the study. Measurements were done at rest and repeated 24 hours after administration of 10 batroxobin units. Plasma fibrinogen, plasma viscosity, and whole blood viscosity were measured as hemorheological factors. MCA blood flow velocity was measured with a transcranial Doppler flowmeter. Blood flow velocity was corrected to 40 mm Hg of end-tidal CO2 partial pressure (PETCO2), and expressed as CV40. CO2 reactivity was measured as percent change in mean blood flow velocity per millimeter of mercury PETCO2. Plasma fibrinogen (from 7.04 to 2.29 mumol/L; P < .001), whole blood viscosity, and plasma viscosity decreased after administration of batroxobin. Mean MCA blood flow velocity at rest, CV40. and CO2 reactivity during hypocapnia increased significantly (from 67.4 to 73.6 cm/s, from 71.7 to 77.7 cm/s, and from 2.9%/mm Hg to 3.2%/mm Hg, respectively; P < .01) after defibrination. Mean arterial blood pressure and PETCO2 at rest were constant before and 24 hours after administration of batroxobin. There was a significant positive correlation between CV40 and CO2 reactivity (r = .623, P < .0001). The increase in MCA blood flow velocity was associated with improved CO2 reactivity and reduced blood viscosity after defibrination. The data may suggest that defibrination increases cerebral blood flow by reducing blood viscosity.

33. Hemostatic and hemorheologic factors in patients with obstructive sleep apnea syndrome (OSAS)

33. Hemostatic and hemorheologic factors in patients with obstructive sleep apnea syndrome (OSAS)

Haemorheological and Cardiovascular Risk Factors in Retinal Vascular Occlusion

Haemorheological and Cardiovascular Risk Factors in Retinal Vascular Occlusion

The role of hemorheological factors in hypertensne retinopathy

Hemorheological factors play an important role in the pathogenesis of different cardiovascular diseases. In the present study the fundus appearance and hemorheological parameters (plasma and whole blood viscosity *WBV* by capillary viscosimetry; fibrinogen level by the Clauss method) of 33 hypertensive patients (23 females, 10 males; mean age: 55 years) were examined. The fundus appearance showed retinopathy in all the cases between stages I-III. All the measured hemorheological parameters of the examined patients were in the pathological range (WBV at 90 lis: 5.18 mPas) and were significantly (p < 0.01) higher than in healthy controls (WBV at 90 lis: 4.18 mPas). The hemorheological factors showed a parallel deterioration with the fundus appearance, namely their values were significantly (p < 0.01) higher in patients with a fundus appearance stage III (WBVat 90 lis: 6.02 mPas) than stage I (WBVat 90 lis: 4.51 mPas). Our results show that there is a correlation between hemorheological parameters and fundus appearance in hypertensives, and this suggests that hemorheological factors may playa role in the development of hypertensive retinopathy.