Clinical Hemorheology and Microcirculation - Volume 30, issue 3-4

Authors: Haider, L. | Snabre, P. | Boynard, M.

Article Type: Research Article

Abstract: Ultrasound scattering technique is used to investigate dynamics of reversible fractal aggregates in dense suspensions and analyze shear break‐up processes of Rayleigh fractal clusters. On the basis of an homogenous fractal flocculation and the hybrid scattering model in the Rayleigh scattering regime, a first order expression of the ultrasound scattering cross‐sectional area per unit of volume (backscattering coefficient) is derived for a dense distribution of correlated Rayleigh fractal clusters. From the scaling laws for shear break‐up of reversible aggregates in concentrated suspensions, a rheo‐acoustical study is then proposed to describe the shear stress dependence of the low frequency scattered power …per unit of volume. In a second part, experimental flow dependent changes of the ultrasound backscattering coefficient in a plane–plane flow geometry were reported to analyze shear break‐up processes of hardened or deformable red cell aggregates in polymer solution (neutral dextran polymer). Rheo‐acoustical experiments were examined within the framework of the effective mean field approximation and the proposed rheo‐acoustical model. The ability of ultrasound scattering to determine the critical disaggregation shear stress inducing a complete disaggregation and to give quantitative information on particle surface adhesive energy are finally analyzed. Show more

Citation: Clinical Hemorheology and Microcirculation, vol. 30, no. 3-4, pp. 345-352, 2004

Authors: Shin, Sehyun | Ku, Yunhee | Park, Myung‐Su | Moon, Soo‐Yeon | Suh, Jang‐Soo

Article Type: Research Article

Abstract: The present study investigated the effect of transverse vibration on the hemo‐rheological characteristics of blood flow using a newly designed pressure‐scanning capillary viscometer. As a transverse vibration was applied, aggregated blood cells become disaggregated. Frequency of vibration was found to be the main parameter causing hemo‐rheological changes. For RBC suspension in a non‐aggregating medium (Dextran 40), increasing frequency of vibration caused decreased flow resistance. Meanwhile, flow resistance for whole blood increased with frequency of vibration. These seemingly contradictory results could be interpreted without conflict when a comprehensive mechanism of cell migration under vibration is elucidated. The present study confirmed that …vibration diminishes RBC aggregation, which triggers two different cell migration mechanisms and subsequently resulted in either increasing or decreasing the flow resistance. Show more

Keywords: Blood, resistance, aggregation, vibration, frequency, cell‐migration

Citation: Clinical Hemorheology and Microcirculation, vol. 30, no. 3-4, pp. 353-358, 2004

Authors: Balan, Corneliu | Balut, Corina | Gheorghe, Liana | Gheorghe, Cristian | Gheorghiu, Eugen | Ursu, George

Article Type: Research Article

Abstract: The paper is concerned with the determination of blood permittivity and conductivity in Poiseuille and Couette simple shear flows. The experimental procedure, based on dielectric spectroscopy, evidences the sensitivity of blood electric properties to the applied frequency and local shear rate magnitude. The method evidences the possibility to correlate (for well‐defined flow geometry) magnitude of shear rate, and consequently the shear stress level, with spectra permittivity of blood.

Citation: Clinical Hemorheology and Microcirculation, vol. 30, no. 3-4, pp. 359-364, 2004

Authors: Brun, Jean‐Frédéric | Aloulou, Ikram | Varlet‐Marie, Emmanuelle

Article Type: Research Article

Abstract: Among hemorheologic parameters, plasma viscosity is one of the most studied in epidemiology, so that it has emerged as an independent risk factor. In diabetes, plasma viscosity is frequently elevated. For this reason we tried to define characteristics of non‐insulin dependent diabetics with high plasma viscosity (>1.45 mPa.s) and whether they were more insulin resistant and/or exhibited other hemorheologic disturbances. 12 subjects (age 56.1±11.7; BMI 28.6±4.8) were thus found to have a value of plasma viscosity >1.45 mPa.s. They were compared to 20 age and BMI‐matched NIDDMs. Patients have similar insulin sensitivity, HbA1c, and fibrinogen. RBC aggregation, rigidity and hematocrit …were not significantly different. Whole blood viscosity at high shear rate was slightly higher (p=0.05). When corrected for hematocrit whole blood viscosity is no longer different. However, hematocrit was not lower in subjects with hpl >1.45. By contrast blood pressure was markedly higher (systolic: 177.5±2.5 mmHg vs 140±8 mmHg, p<10−8 ; diastolic 110±14 vs 83±9 mmHg, p<10−9 ; mean 132±18 mmHg vs 102±7 mmHg p<10−9 ). Therefore, in NIDDM, higher plasma viscosity, regardless insulin resistance and adiposity, is strongly related to blood pressure. Show more

Keywords: Blood viscosity, plasma viscosity, hemorheology, erythrocyte deformability, erythrocyte aggregability, insulin sensitivity, insulin resistance, minimal model, arterial hypertension

Citation: Clinical Hemorheology and Microcirculation, vol. 30, no. 3-4, pp. 365-372, 2004

Authors: Velcheva, Irena | Titianova, Ekaterina | Antonova, Nadia

Article Type: Research Article

Abstract: During the last fifteen years some of our priority scientific topics of research were hemorheological and neurosonographic investigations in 229 patients with different forms of cerebrovascular diseases (CVD): 75 patients with asymptomatic CVD (ACVD), 65 patients with transient ischemic attacks (TIAs) and 89 patients with chronic unilateral cerebral infarctions (UCI). The findings were compared with 70 healthy persons. The main estimated hemorheological parameters were hematocrit (Hct), apparent whole blood viscosity (WBV), plasma viscosity (PV) and fibrinogen (Fib). They were correlated with the following sonographic parameters, obtained by extracranial and transcranial Doppler sonography: blood flow velocities (BFV) and peripheral resistance index …of Pourcelot (RP) of the major arteries of the head and the basal cerebral arteries and vasomotor reactivity indices (VMRI) of the middle cerebral arteries (MCA). Among the hemorheological variables the correlations of Hct with the velocity sonographic parameters predominated in all groups. Significant positive correlations between Hct, WBV and the RP of the internal carotid artery and MCA were found in patients with CVD. In UCI the increase in Hct and Fib was associated with a decrease in BFV of the collateral circulation where aging and high mean blood pressure were additional risk factors for impairment of the cerebral hemodynamics. Plasma viscosity was found to correlate with cerebral VMRI of MCA in patients with UCI. The clinical impact of these findings and their relation to the therapeutic strategy in CVD are discussed. Show more

Keywords: Hematocrit, fibrinogen, whole blood viscosity, Doppler sonography, blood flow velocity, cerebrovascular disease

Citation: Clinical Hemorheology and Microcirculation, vol. 30, no. 3-4, pp. 373-380, 2004

Authors: Antonova, Nadia | Lazarov, Zdravko

Article Type: Research Article

Abstract: Hemorheological and hemodynamic effects of high molecular weight polyethylene oxide (PEO) solutions have been studied in vitro and in vivo at 30 experimental dogs. The rheological behaviour of the PEO solutions and of blood samples has been assessed by rotational viscometers at 20°C, 25°C and 37°C. An addition of PEO solutions to the blood in vitro has modified its rheological behavior, depending on the shear rates, concentration and temperature. Saline with aqueous PEO solutions at the concentration of 500 ppm has been infused into the blood circulation of the experimental dogs to achieve the total concentration in blood of 20–30 …ppm. The following parameters cardiac output, mean arterial blood pressure, central venous pressure, pulse frequency, blood volume flow in the femoral artery, total vascular resistance and blood viscosity before and after the infusion of PEO solutions have been studied. The main observed effect was a decrease of the hemodynamic resistance in the cardiovascular system up to 40% below the baseline after infusion of PEO solutions. Show more

Keywords: Polyethylene oxide solutions, hemorheology, hemodynamics

Citation: Clinical Hemorheology and Microcirculation, vol. 30, no. 3-4, pp. 381-390, 2004

Authors: Varlet‐Marie, E. | Brun, J.‐F.

Article Type: Research Article

Abstract: In a previous paper we determined predictive equations for predicting viscosity parameters with whole body Bioelectrical impedance (BIA) in athletes. We have tried to extend this analysis to a sedentary population. 36 sedentary obese or insulin resistant patients (40.36±2.30 years; 85.77±3.54 kg; 165.93±1.56 cm) were enrolled into this study. Body composition was assessed with a multifrequency bioelectrical impedancemeter Dietosystem Human IM Scan that uses low intensity at the following frequencies: 1, 5, 10, 50 and 100 kHz. Analysis was performed with the software Master 1.0 that gives the choice among 25 published equations for body composition calculation. Viscometric measurements were …done at 1000 s−1 with a falling ball viscosimeter (MT 90 Medicatest). Hematocrit was measured with microcentrifuge. Two hemorheological parameters were independently correlated with impedance (Z) measurements at 50 kHz: whole blood viscosity (WBV) (r=0.541, p=0.01) and hematocrit (Hct) (r=−0.686, p=0.01). New equations slightly different from those we report in the previous paper were found. These findings confirm our previous reports of relationships between whole body electric properties and factors of blood viscosity in athletes and allow the use of BIA to a sedentary population. Obviously, extension of this study will be needed to determine if BIA can be used to generalize predictive equations in both sedentary and trained individuals. Show more

Keywords: Impedance, body fluids, blood viscosity, plasma viscosity, hemorheology

Citation: Clinical Hemorheology and Microcirculation, vol. 30, no. 3-4, pp. 393-398, 2004

Authors: Urdulashvili, T. | Momtselidze, N. | Mantskava, M. | Narsia, N. | Mchedlishvili, G.

Article Type: Research Article

Abstract: It could be conjectured that the hemorheological disorders are involved in development of the ischemic heart disease. But this fact was so far insufficiently cleared up. The present studies were carried out in patients with various forms of chronic ischemic heart disease. We investigated the most significant factor of rheological disorders in the microcirculation, the erythrocyte aggregability, with a technique that provided us with the direct and quantitative data. Simultaneously we investigated in the same patients the tone of the resistance arteries of the hand with an original non‐invasive technique. We found that the erythrocyte aggregability increased almost twice in …the blood of investigated patients as compared to the healthy control group. The aggregability was positively correlated with severity of the disease. The most pronounced hemorheological disorders were found in the patients with the heart failure. As to the arteriolar resistance index, it was increased only in 45 per cent of all the investigated patients and no significant difference between the patients with the heart failure and without it was found available. We concluded that the blood rheological disorders represent themselves a factor that plays a significant role in pathogenesis of development of the heart disease. Show more

Keywords: Hemorheological disorders, arteriolar resistance, ischemic heart disease

Citation: Clinical Hemorheology and Microcirculation, vol. 30, no. 3-4, pp. 399-401, 2004

Authors: Beridze, M. | Momtselidze, N. | Shakarishvili, R. | Mchedlishvili, G.

Article Type: Research Article

Abstract: The aim of study was the investigation of blood nitric oxide (NO) and nitrates (NO2 ) levels in 12 hours of ischemic stroke onset and establishment of correlation of these data with erythrocyte aggregability and initial ischemic lesion size. 48 patients, aged 45 to 70 years, 26 female, 22 male were investigated. Glasgow Coma Scale (GCS) and National Institute Health Stroke Scale (NIHSS) assessed initial neurological impairment. Patients were divided in mild and severe stroke groups. Control comprised 20 healthy individuals. Ischemic lesions were evaluated on conventional MRI scans. NO levels were measured by electron paramagnet resonance (EPR) method. …NO2 levels were defined by spectrophotometer method. Erythrocyte aggregability index (EAI) was measured by sound method [Biorheology 30(2) (1993), 153–161]. Pearson correlation and multivariate model of logistic regression was applied. Significant negative correlation was established between NO initial blood levels and the EAI (r=−0.75; p<0.001), as well as between blood NO2 and NO initial levels and ischemic lesion size (r=−0.79, p<0.01; r=−0.61, p<0.02, respectively). Endothelialy derived NO correlates with erythrocyte aggregability and probably has a positive impact on restoration of cerebral blood flow in the initial stage of acute brain ischemia. Show more

Keywords: Ischemia, nitric oxide, erythrocyte aggregation, microcirculation

Citation: Clinical Hemorheology and Microcirculation, vol. 30, no. 3-4, pp. 403-406, 2004

Authors: Tatarishvili, J. | Momtselidze, N. | Mchedlishvili, G.

Article Type: Research Article

Abstract: Objective: To find whether the principal indices of blood rheological disorders related to the microcirculation undergo drastic changes during the traumatic shock. Methods: RBC aggregability and deformability, as well as the systemic hematocrit, were assessed in white laboratory rats with the techniques that provided us with direct and quantitative data. Results: We found that in the experimental animals the RBC aggregability was sharply increased, the RBC deformability significantly decreased, while the systemic hematocrit underwent considerable lowering during the traumatic shock. Conclusion: The blood rheological properties are significantly disordered during development of the traumatic shock.

Keywords: Microcirculation, blood rheological disorders, experimental traumatic shock

Citation: Clinical Hemorheology and Microcirculation, vol. 30, no. 3-4, pp. 407-410, 2004