Clinical Hemorheology and Microcirculation

We examined the hemodynamic and hemorheological effects of intravenous volume expansion in women with pre‐eclampsia. 20 untreated women with moderate pre‐eclampsia were randomized to receive a 500 ml infusion over 4 h of either hydroxyethylstarch (HAES steril 10%, HES) or NaCl 0.9% solution. After completion of the infusion trial all patients received oral antihypertensive drugs, bed rest and free sodium and water intake. The hemodynamic responses were measured by impedance cardiography. Hemorheological parameters and blood pressure were measured before and after (24 h later) infusion. The HES infusion but not NaCl leads to a significant reduction of hematocrit and erythrocyte aggregation. In addition to that there was a nonsignificant increase of the cardiac index in the HES‐group but no changes in the heart rate. Intravenous volume expansion in women with pre‐eclampsia with a long acting colloid like hydroxyethylstarch is associated with a significant influence on the flow properties (hematocrit and erythrocyte aggregation) of blood.

We previously reported in populations exhibiting all the spectrum of insulin sensitivity (SI) values correlations between SI and blood viscosity η suggesting that high η is an additional symptom of the insulin resistance syndrome. However, due to the elevation of insulinemia (I) which is usually associated with insulin resistance it remained to determine whether this relationship was explained by SI or I. We analyzed SI with the minimal model procedure in 108 nondiabetic subjects and analyzed correlations of SI with blood rheology (η, RBC aggregation and rigidity). Across quartiles of SI (defined after log transformation since distribution of SI was not normal), hematocrit and red cell rigidity remained stable, while aggregability and plasma viscosity (ηp) increased in the lowest quartile. SI was correlated to only two rheological parameters: ηp (r=−0.280, p=0.005) and Myrenne index M1 (r=−0.219, p=0.044). Among SI, I, age and BMI multivariate analysis selected only BMI as a determinant of either whole blood viscosity (ηwb: r=−0.301, p=0.004) and RBC disaggregation threshold (γD: r=−0.331, p=0.013), only I as determinant of M1 (r=0.254, p=0.03), and a combination of BMI (p=0.009) and SI (p=0.007) for ηp. Although age and obesity are factors of hyperviscosity, the hemorheological disturbances found in insulin resistance are not fully statistically “explained” by those two factors. While hyperaggregability (measured with M1) is rather related to hyperinsulinism, ηp is influenced by SI and should be further investigated as a simple marker for the follow up of insulin‐resistant states.

The rouleau formation of erythrocytes and the erythrocyte sedimentation were examined for mixture of different kinds of the cells suspended in isotonic phosphate‐buffered saline containing 1 or 2 g/dl dextran T‐70 (MW = 70,400) and 4 g/dl albumin, using a low shear rheoscope and the Westergren method, respectively. The deformability of cells was decreased by treating with diamide, diazene‐dicarboxylic acid bis[N,N‐dimethylamide], and the sialic acid content of cells, i.e., the surface negative charge, was reduced by treating with neuraminidase. (1) The rate of rouleau formation was decreased in cells with decreased deformability, while it was increased in cells with reduced sialic acid content. The rate changed in proportion to the ratio of the modified cells to normal cells. (2) The erythrocyte sedimentation was also decreased in cells with decreased deformability, while it was increased in cells with reduced sialic acid content. Furthermore, the erythrocyte sedimentation changed almost proportionally to the ratio of the modified cells to normal cells. (3) When normal deformable cells were mixed with cells with decreased deformability, the deformable cells seemed to settle faster than the less deformable cells, though the difference was not significant. (4) When normal cells were mixed with cells with reduced sialic acid content, the cells with less sialic acid settled significantly faster than those with more sialic acid. The present experiment may conclude that erythrocyte aggregation is induced preferentially among more deformable cells and/or among less negatively charged cells with weaker electrostatic repulsive force, and then the formed aggregates settle faster.

The aim of this study was to evaluate coagulative and hemorheologic assessment in patients with dilatative cardiomyopathy with or without spontaneous echo contrast (SEC). We studied 45 patients, 35 males and 10 females (mean age 72.1±9.2). We measured whole blood viscosity, plasmatic fibrinogen, prothrombin time (PT), activated partial thromboplastin time (aPTT), D‐dimer and red cell morphology with Zipursky–Forconi method. Transthoracic and transesophageal echocardiography was performed in all patients to evaluate the presence of SEC in left atrium. We divided all the patients into two groups: the 1st group of 20 patients with SEC and Atrial Fibrillation (AF) in 80% of cases, and the 2nd group of 25 patients without SEC and AF in 31%. Our results show that in patients with SEC there is a statistically significant increase of whole blood viscosity and plasma fibrinogen in comparison with patients without SEC. Red cell morphology in all patients demonstrates a reversed EMI. D‐Dimer, was out of the normal range in about 1/3 of the patients in both groups. An analysis of our results points out that in patients with SEC and AF, with a major risk factor for cardioembolic stroke, we have alterations of hemorheologic assessment with an increase of whole blood viscosity and fibrinogen that seems to be caused by an increase of red cells aggregability favoured by fibrinogen. Our conclusions are that SEC in patients with dilatative cardiomyopathy and AF is an important in vivo indicator of hemorheologic imbalance and an important marker for cardioembolic risk stroke evaluation.

The purpose of this in vitro study was to assess the effect of 17β‐estradiol on hemorheologic parameters, namely on erythrocyte aggregation and deformability and membrane fluidity.

Blood samples from 65 women (aged 57±4 years) undergoing postmenopausal hormone replacement therapy were obtained and were incubated for 5 min in absence and presence of 17β‐estradiol 10⁻⁵ M. The measured parameters were the erythrocyte aggregation (EAI) and deformability (EI), the acetylcholinesterase activity (AChE), the plasma pH and osmolality and the erythrocyte membrane fluidity assessed by fluorescence polarization with two probes 1,6‐diphenyl‐1,3,5‐hexatriene (DPH) and (1‐(4‐(trimethylamino)‐phenyl)‐6‐phenyl‐1,3,5‐hexatriene (TMA‐DPH). Data analysis was performed using t‐Student and Pearson correlation analysis.

A statistically significant decrease of the EAI (15.8±3.02 vs 13.45±2.3; p<0.001) and an increase of the EI (51.39±5.64 vs 52.06±5.36; p<0.01) at shear stress of 30 Pa in presence of 17β‐estradiol 10⁻⁵ M was obtained. There was a decrease in membrane fluidity in 45 blood samples (DPH) and in the other 20 an increase, when β‐estradiol 10⁻⁵ M was present.

In vitro β‐estradiol 10⁻⁵ M decreased erythrocyte aggregation in blood samples of postmenopausal women undergoing hormone therapy, which could prevent high blood viscosity and, consequently, cardiovascular events.

Changes in hemorheological parameters were studied in patients with ischemic cerebrovascular disease and elderly healthy men who ingested ethanol at 0.5 and 1 g/kg body weight. Following ingestion of 1 g/kg, but not 0.5 g/kg of ethanol, there were significant changes in hemorheologic factors. Whole blood viscosity (WBV, shear rate: 18.8, 37.5, 75, 150, 350 sec⁻¹) and blood viscosity corrected for hematocrit (BVC) were increased. WBV and BVC at high shear rate were increased and red blood cell deformability impaired in patients with ischemic cerebrovascular disease, while those factors were not significantly changed in healthy men. It is considered that ethanol ingestion could has bad influences for the microcirculation in patients with ischemic cerebrovascular disease.

The aim of this study was to test the hypothesis that exposure of red blood cells (RBC) to low‐power laser energy can modulate their metabolism and deformability. The effects of exposure to a He–Ne (λ=632.8 nm), GaAlAs (λ=780 nm) and GaAs (λ=904 nm) lasers have been examined. Red cells diluted to a hematocrit of 45% were incubated in a humidified atmosphere of 95% air and 5% CO₂ at 37°C, and exposed to three different laser beams held 5 cm from the target area to yield a spot surface area of 2 cm². Three red cell suspensions belonging to the experimental groups were treated with each laser beam by 5, 15 and 30 minutes, respectively. The temperature was constant during the exposure's time. Three control suspensions of RBC were kept for the same time as sham‐irradiated groups. The erythrocyte elongation index (EEI) was evaluated using a Rheodyn SSD (Myrene, Roetgen, Germany). The enzyme activities of glucose‐6‐phosphate dehydrogenase (G‐6‐PD), glutathione peroxidase (GSH‐Px) and glutathione reductase (GR) were assayed in each sample spectrophotometrically. Adenosine triphosphate (ATP) and diphosphoglicerate (2,3‐DPG) levels were also assessed. No statistical differences were observed in the erythrocyte elongation index at shear stresses of 0.30, 0.60, 1.20, 3.00, 6.00, 12.00, 30.00 and 60.00 Pa after being irradiated for 5 and 15 minutes as compared to not irradiated ones. At 30.00 and 60.00 Pa a decrease (p<0.03 and p<0.05, respectively) in EEI has been observed after 30 min exposure to all three wavelengths of laser light when compared to the control. The antioxidant enzyme activities showed no significant changes following 5, 15 and 30 min of irradiation by all three laser wavelengths laser tested. Similarly, erythrocyte organic phosphate levels (ATP and 2,3‐DPG) showed no significant changes following treatment by laser radiation. This study revealed that the low‐power laser at 632.8, 780 and 904 nm wavelengths have little biological effects on red blood cells in vitro.

Purpose of the study: To determine the effects of acetylcholine and SpermineNONOate – a NO donor – on RBC membrane and oxygen carrying properties. Material and methods: Aliquots of venous blood from eleven heathy subjects were incubated with ACh 10⁻³ M, ACh 10⁻⁵ M, SpermineNONOate 10⁻⁵ M and SpermineNONOate 10⁻⁴ M. The following parameters were determined: erythrocyte aggregation and deformability, hematocrit, plasma pH, osmolality, K⁺, Na⁺, Ca²⁺ concentrations, hemoglobin, oxyhemoglobin, carboxihemoglobin and methemoglobin concentrations, oxygen saturation of hemoglobin, oxygen and carbon dioxide parcial pressures and p50. Results: In presence of ACh there is an increase of erythrocyte deformability, decrease of erythrocyte aggregation, plasma pH, K⁺ and Na⁺ concentration, increase of Ca²⁺ concentration and p50. In presence of SpermineNONOate there an increase of erythrocyte deformability, plasma pH, decrease of Na⁺ and Ca²⁺ concentration, increase of metHb concentration and decrease of p50. Conclusion: Acetylcholine and SpermineNONOate are able to induce changes on RBC membrane and oxygen carrying properties.

Risk factors for atherothrombosis including increased leukocyte count, hyperlipidemia, diabetes mellitus, hypertension as well as smoldering inflammation and hyperfibrinogenemia might affect the aggregability of peripheral blood erythrocytes, leukocytes as well as platelets. We have used a simple slide test and image analysis to reveal the presence of these aggregabilities obtained in one single drop of peripheral venous citrated blood in 48 individuals with risk factors for atherothrombosis. A significant correlation was noted between the state of adhesiveness/aggregation of all the above mentioned three cellular elements and the concentrations of total and LDL cholesterol. The correlation with triglycerides concentrations was more modest. A significant reduction of adhesiveness/aggregation was noted in 18 individuals following an intervention to reduce the concentration of cholesterol and triglycerides. This reduction might have a favorable hemorheologic effect. Our results are significant in that they show that it is possible to detect the above mentioned changes in whole blood, following a single step and minimal manipulations, at real time and low cost.