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At least 19 recordsLinked to original sources
PubMed2006

Hemorheologic profile in systemic sclerosis: role of NOS3 -786T > C and 894G >T polymorphisms in modulating both the hemorheologic parameters and the susceptibility to the disease.

OBJECTIVE: Microvascular disorders are relevant in systemic sclerosis (SSc). Hyperviscosity, due to alterations of blood cells and plasma components, may play a role in the pathogenesis of microcirculatory disorders. An impaired availability of nitric oxide, related to polymorphisms in NOS3, the gene for endothelial cell nitric oxide synthase, might influence erythrocyte deformability. We undertook this study to investigate the hemorheologic profile in SSc and the role of NOS3 polymorphisms in modulating the hemorheologic status of SSc patients. METHODS: We studied 113 consecutive SSc patients (75 with limited cutaneous SSc [lcSSc] and 38 with diffuse cutaneous SSc [dcSSc]) and 113 healthy controls. The hemorheologic profile was obtained by assessing whole blood viscosity (WBV; at shear rates of 0.512 and 94.5 seconds(-1)), plasma viscosity (PLV; at a shear rate of 94.5 seconds(-1)), and erythrocyte deformability index (DI). We determined NOS3 polymorphisms by molecular analysis. RESULTS: A marked alteration of hemorheologic parameters was found both in patients with lcSSc and in those with dcSSc compared with controls (P < 0.0001). In multivariate analysis, rheologic variables were significantly associated with the disease (for WBV at a shear rate of 94.5 seconds(-1), odds ratio [OR] 5.4, 95% confidence interval [95% CI] 1.4-19.9, P = 0.01; for PLV, OR 2.8, 95% CI 1.2-6.5, P = 0.01; for DI, OR 3.9, 95% CI 1.4-10.8, P = 0.007), and NOS3 -786C and 894T alleles significantly affected the DI (for -786C allele, OR 2.3, 95% CI 1.01-5.4, P = 0.04; for 894T allele, OR 2.2, 95% CI 1.01-4.8, P = 0.04). The simultaneous presence of the -786C and 894T alleles represented a susceptibility factor for SSc (OR 2.8, 95% CI 1.4-5.7, P = 0.004). CONCLUSION: Our findings document an altered rheologic profile in SSc and demonstrate a relationship between this alteration and NOS3 polymorphisms, thus shedding light on a potential novel mechanism influencing the microcirculation in this disease.

Aged↗
PubMed1984

The Aachen clinical hemorheology test profile: a proposal for the documentation of hemorheological data in clinical medicine.

The recent development of specific methods to measure directly the microrheological determinants of blood fluidity allows to complement or even substitute global measurements of whole blood apparent viscosity or filtrability through sieves containing restricted pores. While such differentiation is mandatory for practical and theoretical reasons, there is the danger of loosing coherence of measurements essential for correlating hemorheology to other sciences. In an attempt to document hemorheological data in a simple yet comprehensive fashion, a test profile for the display of normalized data from subtests on hematocrit, plasma viscosity, red cell "rigidity" and tendency to red cell aggregation is proposed. Using procedures developed in the behavioural sciences, stringend criteria for evaluating the validity, reliability, standardization, economy and usefulness of individual subtests for the blood viscosity determinants and a compounded hemorheology test profile are proposed. There is good evidence that abnormal hemorheological behaviour of red cell plasma mixtures manifest themselves exclusively in situations associated with grossly reduced in vivo driving pressures and thence shear stresses. In these situations, in which a low flow state is caused by general hemodynamic changes, there is a danger that the blood looses its normal fluidity and undergoes a reversible viscidation: We propose the hypothesis that in these situation abnormally blood poses a risk of a flow limitation (and even interruption) by rheological abnormalities described above. The test profile presented has been developed to supply a more valid experimental method for subjecting the above hypothesis to experimental tests in the clinical situation.

Blood Physiological Phenomena↗
PubMed1991

[Hemorheology in clinical practice. Introduction to the notion of hemorheologic profile].

Although the non-Newtonian characteristics of blood have now been accurately defined, the influence and effect of a hyperviscosity syndrome at the onset of ischemia and in oxygen transport to the tissues remains within the realm of assumptions. Using a simple theoretical approach it can be shown that oxygen transport capacity to the tissues is proportional to the radio H/eta s (where H = hematocrit, eta s = blood viscosity), as long as vascular bed geometry remains constant (with no sign of compensatory vasodilation). With the help of examples, the authors show the changes in oxygen transport as a function of various rheological parameters (red cell aggregation ans deformability). Further, the authors introduce the concept of a hemorheological profile for taking all the hemorheological parameters into consideration and for standardising the presentation of the results for hyperviscosity syndromes.

Blood Viscosity↗
PubMed1998

Insights into the relationship of fatty streaks to raised atherosclerotic lesions provided by the hemorheologic-hemodynamic theory of atherosclerotic lesions provided by the hemorheologic-hemodynamic theory of atherogenesis.

The hemorheologic-hemodynamic theory of atherogenesis suggests that atherosclerosis is a disease of low shear, which prolongs the residence time of atherogenic particles on the endothelium. Prolonged residence of lipid-rich particles results in a fatty streak. Prolonged residence of platelet microthrombi results in a raised lesion (atherosclerotic plaque). Thus, fatty streak and raised lesion development are independent processes. In contrast, received wisdom holds that fatty streaks are the precursors to raised lesions. The author examines anatomic and risk factor data for fatty streaks and raised lesions, including the results of the recent multicenter Pathobiological Determinants of Atherosclerosis in Youth study, in light of these two theories.

Aorta, Thoracic↗
PubMed2004

Reciprocal relationships between blood lactate and hemorheology in athletes: another hemorheologic paradox?

Blood lactate increases during exercise. Although this increase was classically interpreted as a "Pasteur-like effect" resulting from anaerobiosis, it is now clear that it mostly results from a shift in the balance of oxidation of substrates in the muscle, with carbohydrate becoming the predominant fuel. However, we have repeatedly observed that the rise in blood lactate during exercise is correlated to blood viscosity and red cell aggregation. More recently we investigated this issue with the modelling of postexercise lactate kinetics, that allows a fair evaluation of lactate production by muscles (gamma1) and lactate disappearance (gamma2). Postexercise red cell aggregation (Myrenne M1) appears to be correlated to gamma2. Thus microcirculatory adaptations influenced by red cell aggregation may influence lactate disposal, adding its effect to that of the balance between carbohydrates and fat. On the other hand, the rise in blood lactate seems to induce some alterations in erythrocyte rheology at exercise. Correlations between its concentrations during exercise and erythrocyte rigidity support the concept that lactate, at least when it rises above the 4 mmol.l(-1) threshold impairs red cell deformability. Moreover, it seems that endurance training influences erythrocyte response to lactate. While lactate did not in vitro affect erythrocyte aggregation, it impaired (as expected) erythrocyte deformability in sedentary subjects but it (unexpectedly) improved it in trained subjects. This difference may be due to training-induced adaptations in erythrocyte metabolism, including transmembrane transfer via monocarboxylate transporters which show marked alterations in this context. This specific training-induced pattern of response to lactate may provide an alternative explanation to the exercise-induced arterial hypoxemia that occurs in such athletes.

Blood Viscosity↗
PubMed1991

New trends in clinical hemorheology: an introduction to the concept of the hemorheological profile.

It has now been clearly established that blood behaves like a non-Newtonian fluid exhibiting specific features with the probable existence of a plasticity threshold, a viscosity that varies as a function of shear rate and a non-homogeneous nature of the medium during flow. When apparent blood viscosity is represented as a function of shear rate, a high viscosity is observed at low shear rates, mainly due to rouleaux formation or red cell aggregates. At high shear rates, viscosity decreases. Apparent blood viscosity is mainly dependent on the following parameters: cell volume concentration (hematocrit); plasma viscosity (which is itself dependent on the type and concentration of the proteins); mechanical properties of the red cells, the main determinants being the cell membrane and internal viscosity; red blood cell aggregation; shear stress applied. Pathological changes in one of the factors controlling blood viscosity and the resulting clinical symptoms constitute the hyperviscosity syndromes. The field of hyperviscosity syndromes concern the situations where the increased blood viscosity and the accompanying modifications in flow resistance must be considered as being the result of the overall rheological behaviour of blood. In this general context, hyperviscosity syndromes can be divided into 4 main groups: 1. Increase in the number of blood cells (mainly red cells) 2. Increase in the plasma protein concentrations or the appearance of high amounts of a monoclonal protein 3. Increase in internal red cell viscosity or a change in the mechanical properties of the erythrocyte membrane 4. Increase in erythrocyte aggregation (formation of barely or in no way dissociable aggregates). Considered from a hemodynamic viewpoint, the appearance of a hyperviscosity syndrome could (by 'feed back' mechanisms) enhance the phenomenon and slow down blood flow or even stop flow completely, thus making ischemia and thrombosis easier. Further, the appearance of the syndrome also results in a decrease in the blood's overall oxygen transport capacity, which, at a primary approach, is proportional to the ratio hematocrit/blood viscosity.

Animals↗
PubMed1985

[Fundamental data in hemorheology. I. Parameters controlling the fundamental processes in hemorheology].

When attempting to apply rheological concepts to the problem of the circulation of blood, researches have often come up against the difficulties inherent in the fluid's specific properties and in the characteristics of blood flow. The concepts that have been fully proven in conventional fluid mechanics have often been applied too hastily to hemodynamics, without even ascertaining the validity of the original hypotheses. The following factors must be taken into account: the specific nature of the fluid (a concentrated cell suspension with complex rheological characteristic such as membrane viscoelasticity, large deformations and liable to undergo high interactions); the characteristics of the blood vessels deformability; the type of flow (essentially non-stationary).

Biomechanical Phenomena↗
PubMed1999

Hemorheological and hemodynamic parameters in patients with essential hypertension and their modification by alpha-1 inhibitor drug treatment.

Hemorheological factors play an important role in the pathogenesis of different cardiovascular diseases. The hemorheological and hemodynamic parameters in essential hypertension and their possible modification by antihypertensive treatment were examined in the following two studies. In the first study the fundus appearance and hemorheological parameters (plasma and whole blood viscosity (WBV), fibrinogen level) of 33 hypertensive patients (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 s(-1): 5.18 mPa s) and were significantly (p < 0.01) higher than in healthy controls (WBV at 90 s(-1): 4.18 mPa s). 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 (WBV at 90 s(-1): 6.02 mPa s) than stage I (WBV at 90 s(-1): 4.51 mPa s). These results show that there is a correlation between hemorheological parameters and fundus appearance in hypertensives, and this suggests that hemorheological factors may play a role in the development of hypertensive retinopathy. In the second study the hemorheological and hemodynamical effects of Doxazosin, a selective alpha-1-adrenoreceptor blocker agent, was examined in twenty patients (mean age: 54 years) with essential hypertension. Hemorheologic (hematocrit, fibrinogen, plasma and whole blood viscosity) and hemodynamic (cardiac output and index, total peripheral resistance) parameters and plasma lipids were determined. The measurements were carried out before the beginning of the treatment, after 1 week and after 12 weeks treatment periods. Besides significant reduction of blood pressure and total peripheral resistance (p < 0.001), a decrease in cholesterol (p < 0.001) and triglycerides (p < 0.01) levels and a beneficial effect on hemorheological parameters was detected. Fibrinogen and plasma viscosity decreased significantly (p < 0.01). Hematocrit value was also lower after one week (p < 0.001), then an increase could be seen. Whole blood viscosity showed similar changes as hematocrit, but the degree of its final increase was slighter, which was supported by the significantly lower value of corrected blood viscosity (p < 0.05). All these findings indicate that hemorheological factors may play a role in the pathogenesis and in the development of organ damages in hypertension.

Adrenergic alpha-Antagonists↗
PubMed2002

Exercise hemorheology as a three acts play with metabolic actors: is it of clinical relevance?

Hemorheological effects of exercise are a triphasic phenomenon including: (a) short-term effects (hyperviscosity mostly due to fluid shifts and alterations of erythrocyte rigidity and aggregability); (b) middle-term effects (i.e., the reversal of acute effects due to plasma volume expansion (autohemodilution) that lowers both plasma viscosity and hematocrit; (c) long-term effects that further improve blood fluidity, parallel with the classical training-induced hormonal and metabolic alterations. Red cell rheology during these 3 stages is affected by white cells and oxidant stress. On the other hand, most metabolic and hormonal alterations play a role in exercise-induced hemorheological changes: among them, blood lactate appears to have opposite effects according to the training status, since it generally impairs erythrocyte fluidity while it improves it in some subgroups of highly trained athletes, a difference that could be related to membrane monocarboxylate transporter status. Body composition (mostly hydration status and the amount of fat mass) as well as its major hormonal regulating system (the growth-hormone-IGF-I axis) are both markedly modified by training and these modifications are correlated with hemorheology. Nutritional disturbances affecting caloric and proteic intake, lipids, iron, zinc, etc. also modulate the hemorheologic effects of exercise. The overtraining syndrome represents a situation of unbalance between body's possibilities, nutrition, and work load, and is associated with metabolic, hormonal, immunologic and hemorheologic disturbances. The clinical relevance of these data is underlined by studies showing that exercise training in patients suffering from metabolic and/or cardiovascular disorders (such as the insulin resistance syndrome) results in a parallel improvement of metabolism, risk factors, blood rheology and fitness. Hemorheological measurements require to be studied, at least as sensitive markers of training, and possibly as "true" risk factors highly sensitive to exercise intensification.

Blood Cells↗
PubMed1996

[Outlook for clinical hemorheology].

Harvey may be considered to be the precursor of modern hemorheology, but it was not until the pioneering work of Loewenhoeck, Poiseuille, Fahraeus and Copley that the essential role of the hemorheological properties of blood and its cellular components was recognized. Before the advent of modern hemorheology in the 70s, studies were mainly focussed on microcirculation and validation of global hemorheological equations applied to blood circulation. Parallel studies on the microrheological properties (erythrocyte deformability and aggregation) explained analytically the non-Newtonian behavior of blood, and the essential contribution of these parameters to the understanding hyperviscosity syndromes. The development of clinical hemorheology in fact started at the international conferences held in Reykjavik (1966) and Heidelberg (1969), and with the initiation of the periodical European Microcirculation (since Nancy in 1960) and Clinical Hemorheology (since Nancy in 1979) Conferences. The current main avenues of research involve flow modelling, studies of cell-cell interaction mechanisms (aggregation and adhesion), in relation to the associated pathophysiological phenomena, such as cellular activation (platelets and leukocytes in particular), gene expression linked to blood flow (e.g. endothelial cells)... Clinically and therapeutically, it is crucial that pathophysiological studies be undertaken on the relationship existing between rheological parameters and objective clinical data (local flow rates, ischemic markers, hemostatic parameters, tissue oxygen, clinical symptoms,...). The main clinical application fields are cardiovascular diseases, thrombosis, diabetes, hypercholesterolemia... Also, studies on new therapeutics or on biomaterials should also be given priority.

Blood Viscosity↗
PubMed1997

Retrospective analysis of long-term hemorheologic effects of pentoxifylline in diabetic patients with angiopathic complications.

Blood rheology alterations have often been reported in diabetic patients and may be associated with an increased risk for diabetic vascular disease. In this light a hemorheologic approach with pentoxifylline has been suggested in diabetic patients with hemorheological changes in order to improve the hemorheology approach and to evaluate the long-term effects of this treatment on the other clinical and metabolic variables. The study concerned a 10-year retrospective analysis of diabetic patients with hemorheologic alterations and angiopathic complications. Pentoxifylline (Trental 400) significantly reduced blood and plasma viscosity (at high and low shear-rates), fibrinogen and erythrocyte aggregation, and increased erythrocyte filterability throughout the study. The improvement of the hemorheologic pattern was obtained independently of the variation in glycometabolic control and body weight changes, whereas concomitant reductions of arterial blood pressure levels and of urinary excretion of albumin and total proteins was observed during the treatment. Pentoxifylline might therefore be successfully employed for long-term periods in the treatment of hemorheologic disorders in diabetic patients without effects on the metabolic pattern.

Adult↗
PubMed1998

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.

Journal Article↗
PubMed1998

Hemorheological changes during human aging.

Various researchers have reported an association of hemorheological, hematological and metabolic changes with human aging. In this article an attempt has been made to review the present understanding of hemorheological changes and their probable role in the development of certain disorders/diseases during aging. The rise in fibrinogen, blood viscosity, plasma viscosity, red cell rigidity, fibrin degradation products and early activation of the coagulation system are some of the most prominent findings. It is generally agreed that a rise in blood viscosity factors leads to a state of hypoperfusion which results in impaired microcirculation. The cumulative effect of these changes appears in the form of a disturbed blood flow profile in older subjects leading to the development or aggravation of various circulatory disorders. Many studies indicate that hemorheological parameters that change in a number of diseases prevalent during aging include hypertension, stroke, diabetes. In addition correlations found between hemorheological parameters in the aged and decrements in certain cognitive functions and behavioral patterns suggest that hemorheological changes contribute to nonclinical aging changes.

Aged↗
PubMed2000

A study of hemorheological behaviour for patients with Alzheimer's disease at the early stages.

To evaluate the change of hemorheological indexes for patients with Alzheimer's disease (AD) at the early stages and to discuss effects of these changes on AD, high shear value of whole blood viscosity (etabh), reduced high shear value of whole blood viscosity (retabh), low shear value of whole blood viscosity (etabl), reduced low shear, value of whole blood viscosity (retabl), KT value of whole blood viscosity, hematocrit (HCT) and blood plasma viscosity (etaP) were measured in 31 patients with probable AD at the early stages and 33 age-matched healthy subjects. There were significant differences of all hemorheological indexes between AD group and control group except HCT. Step discriminant analysis revealed 81.25% of overall group-classified accuracy in a hemorheological discriminant function consisting of etabl, retabl, retabh and HCT. Significant difference of hemorheological indexes existed between AD and age-matched healthy control subjects. The results showed that measurement of hemorheological indexes could be used as one of reference standards of diagnosis in AD.

Aged↗
PubMed2001

Impaired hemorheological properties in diabetic patients with lower limb arterial ischaemia.

The rheological properties of blood play an important role in the regulation of blood flow resistance in vessels. Numerous data show evidence for an impaired hemorheological characteristic in diabetes mellitus. The aim of this study was to investigate whether chronic severe leg ischaemia in diabetes may be associated with further hemorheologic impairment. To do this, whole blood viscosity, erythrocyte aggregation/disaggregation, plasma viscosity and proteins were measured in 32 healthy control subjects, in 32 diabetic patients without micro- and macroangiopathy, in 21 diabetic patients with chronic tissue hypoxia of lower limbs and in 23 diabetic patients with severe leg ischaemia. The diabetic patients with leg hypoxia and leg ischaemia were selected according to their value of transcutaneous oxygen pressure (TcPO2) measured on dorsal side of the foot in supine position. The TcPO2 value was within 10-30 mmHg or less than 10 mmHg in patients with chronic hypoxia and severe ischaemia, respectively. Results in diabetic patients without micro- and macroangiopathy showed an increased erythrocyte aggregation associated with an increased fibrinogen level while albumin levels were decreased. Both diabetic patients with chronic hypoxia and those with severe ischaemia exhibited similarly more aggravated hemorheological disturbances including an increased whole blood viscosity at low shear rate, an increased erythrocyte hyperaggregation, increased plasma viscosity, increased fibrinogen level, decreased albumin level and decreased hematocrit. In conclusion, the hemorheological disturbances are present even in diabetic patients without clinically detectable micro- and/or macroangiopathy. The fact that the extent of disturbances was similar in the two later diabetic groups, emphasizes that the hemorheological disturbances are not the consequences of chronic hypoxia and/or severe ischaemia but are likely among factors promoting the maldistribution of blood flow in nutritive capillaries as evidenced by decreased TcPO2 in patients with chronic leg hypoxia or severe leg ischaemia.

Adult↗
PubMed2003

[Effects of cardiovascular risk factors on hemorheologic parameters in cerebrovascular patients].

INTRODUCTION: Hemorheological factors are of significance in the determination of flow characteristics of blood and play an important role in the pathogenesis of cerebrovascular diseases. AIMS AND METHODS: In this study the changes of rheological factors--hematocrit (Hct), plasma fibrinogen concentration (PFC), whole blood (WBV) and plasma viscosity (PV), red blood cell aggregation (AI) and deformability and the association between these parameters and cardiovascular risk factors were investigated in 297 patients (173 males, 124 females, mean age: 60 11 years) with chronic phase (3 months after onset) ischemic cerebrovascular diseases, and in 68 healthy volunteers (30 males, 38 females, mean age: 36 6 years). RESULTS: All investigated hemorheological factors were significantly (p < 0.05-0.0001) elevated in cerebrovascular patients compared to normal controls, the rise in Hct, WBV and PV are some of the most prominent findings. In the group of hypertensive, hyperlipidemic patients, smokers and alcoholics Hct, PFC, WBV, PV and AI were significantly (p < 0.05-0.0001) higher compared to healthy controls, the same factors except plasma fibrinogen concentration showed association with diabetic history. Comparing cerebrovascular patients with or without risk factors, the most severe hemorheological deficit was observed in patients with hyperlipidemia and smoking habits. CONCLUSIONS: In this study the authors proved in chronic ischemic cerebrovascular patients that hemorheological abnormalities persist in most cases for a long time after an acute stroke, significant correlation could be seen between blood rheology and cardiovascular risk factors. Examination of rheological parameters can support to choose the optimal medical treatment in the secondary prevention of stroke, correction of hemorheological disturbances can reduce the risk of recurrent stroke.

Adult↗