Clinical Hemorheology and Microcirculation - Volume 26, issue 4

Authors: Dumortier, M. | Pérez‐Martin, A. | Pierrisnard, E. | Mercier, J. | Brun, J.F.

Article Type: Research Article

Abstract: Exercise training decreases blood viscosity in athletes parallel with metabolic improvements mostly characterized by an increase in insulin sensitivity. Patients with low insulin sensitivity exhibit a host of metabolic disorders that may also benefit from regular training. However, the hemorheologic aspects of training in such subjects are not known and we aimed at characterizing them. Subjects: Thirty‐two obese insulin resistant subjects were tested before and after 2 months. Twenty‐one of them were trained (3×45 min/wk) at a level defined by exercise calorimetry and corresponding to the power at which lipid oxidation reaches a maximum (LIPOXmax  ) and eleven served as …controls. The two groups were matched for age and body mass index. There was no weight change in controls while the 2 months training period decreased weight by 2.5 kg (p<0.02). This change was totally explained by a loss in fat mass (−2.7 kg, p<0.02) while fat free mass remained unchanged. Blood rheology was unchanged in the control group while training improved plasma viscosity ηpl (before: 1.43±0.03 mPa.s; after: 1.35±0.03 mPa.s, p<0.02). There was no change in either hematocrit, red cell rigidity or red cell aggregation. The balance of substrates oxidation shifted towards a higher use of lipids (point of crossover where subjects oxidize 70% carbohydrates 30% lipids: before 39.3±6.9 watts; after 70.8±6 watts, p<0.001; point where lipid oxidation is maximal (LIPOXmax  ) before: 16.5±1.4 watts; after: 21.4±1.3 watts, p<0.001) and VO2max  increased by 74% (p<0.01). Consistent with observations in athletes, the metabolic and ergometric improvements induced by training reduces ηpl in sedentary, insulin resistant patients, but at those low levels training does not appear to induce “autohemodilution” (as reflected by hematocrit) neither it improves red cell deformability or aggregation. The reliability of ηpl as simple and unexpensive marker of efficiency of training in insulin resistant patients should be further evaluated. Show more

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

Citation: Clinical Hemorheology and Microcirculation, vol. 26, no. 4, pp. 219-229, 2002

Authors: Brun, J.F. | Belhabas, H. | Granat, M.Ch. | Sagnes, C. | Thöni, G. | Micallef, J.P. | Mercier, J.

Article Type: Research Article

Abstract: In three separate studies, we have observed that the rise in blood lactate during exercise is correlated to blood viscosity and red cell aggregation. Whether these results were related to an effect of blood rheology on lactate production by muscles or on lactate disappearance remains unknown. The modelling of postexercise lactate kinetics allows a fair evaluation of lactate production by muscles (γ1) and lactate disappearance (γ2), the latter being easily measurable with simplified protocols. We thus investigated the relationships between pre‐ and postexercise blood rheology and γ2. Ten subjects (2 female and 8 males; age 16–45 yr, weight 62–106.5 kg) …exhibiting a wide range of γ2 (from 2 to 7.7×10−2 min−1 ) underwent a maximal exercise‐test with postexercise calculation of γ2 with the simplified formula γ2=0.0724+0.755(Lac8−Lac20)/(Lac8·Δt)−0.00684Lac20 where Lac8 and Lac20 are lactate concentrations 8 and 10 min after exercise stop at the level of VO2max  , as previously reported. During exercise whole blood viscosity ηb increased (+15%, p<0.01) due to a rise in hematocrit (p<0.05) and plasma viscosity (+0.08±0.03 mPa.s, p<0.05), while red cell rigidity was unchanged. Red cell aggregation (Myrenne M1) increased by 11% (p<0.05). Postexercise M1 (measured at VO2max  ) was the only hemorheologic parameter correlated to γ2 (r=−0.697, p=0.037). We find once again a statistical relationship between lactate at exercise and red cell aggregation. Microcirculatory adaptations influenced by red cell aggregation may influence lactate disposal (as reflected by γ2), adding its effect to that of the balance between carbohydrates and fat oxidation which is the major determinant of blood lactate concentrations at exercise in physiological conditions. Show more

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

Citation: Clinical Hemorheology and Microcirculation, vol. 26, no. 4, pp. 231-239, 2002

Authors: Lo Presti, R. | Sinagra, D. | Montana, M. | Scarpitta, A.M. | Catania, A. | Caimi, G.

Article Type: Research Article

Abstract: Metabolic Syndrome (MetS) has been defined as a clinical condition including impaired glucose tolerance or diabetes mellitus and/or insulin‐resistance, associated with two or more of the following components: arterial hypertension, central obesity, dyslipidaemia, microalbuminuria. In a group of subjects with MetS we examined the macrohaemorheological profile, demonstrating a significant increase of blood, plasma and serum viscosity and a decrease of whole blood filterability. The results show that in these subjects a secondary hyperviscosity condition is present, but also that several significant correlations are present between the haemorheological variables and some aspects of MetS, especially those reflecting central obesity (waist to …hip ratio) and insulin‐resistance. The altered haemorheological profile likely contributes to explain the high cardiovascular risk present in MetS, but it may also participate, through its influence on haemodynamic pattern, in the pathogenesis of insulin‐resistance. Show more

Keywords: Insulin‐resistance, obesity, diabetes mellitus, essential hypertension, blood rheology

Citation: Clinical Hemorheology and Microcirculation, vol. 26, no. 4, pp. 241-247, 2002

Authors: Shand, Brett | Gilchrist, Nigel | Blackwell, Terri | March, Rachel

Article Type: Research Article

Abstract: Raloxifene, the prototype of the selective estrogen receptor modulators, has been associated with an increased risk of venous thromboembolism. As hemorheological factors may be involved in thrombus formation this placebo‐controlled study investigated whether raloxifene was associated with changes in determinants of blood viscosity. Fifty‐seven post‐menopausal women were randomly assigned to receive placebo, raloxifene 60 mg/day, or raloxifene 120 mg/day for 36 months. Venous blood samples were collected at baseline and at 12‐monthly intervals and used to measure hematocrit, whole blood and plasma viscosity and plasma fibrinogen concentration. Time‐ and treatment‐related changes in the grouped and pooled data was analysed using …ANOVA with repeated measures and correlation matrices. The mean values of all the hemorheological indices showed small inconsistent changes within the normal reference range over the 36‐month period of the study. There was a small but significant decrease over time in high shear rate blood viscosity and plasma viscosity in raloxifene‐treated subjects compared to those receiving placebo (p<0.05). Correlation analyses showed the anticipated relationships between blood viscosity and hematocrit and plasma viscosity levels and also between plasma viscosity and plasma fibrinogen concentration. No subject developed a thromboembolic vascular event during the study. These results show that compared with placebo treated‐subjects, long‐term raloxifene treatment in post‐menopausal women, at a dose of either 60 or 120 mg daily, was not associated with adverse changes in hemorheological factors that may contribute to venous thromboembolism. Show more

Keywords: SERM, raloxifene, post‐menopause, hemorheology, venous thromboembolism, clinical trial

Citation: Clinical Hemorheology and Microcirculation, vol. 26, no. 4, pp. 249-255, 2002

Authors: Ercan, Meltem | Konukoğlu, Dildar | Erdem, Tijen | Önen, Sinan

Article Type: Research Article

Abstract: Red blood cell (RBC) deformability is an important hemorheological parameter to determine the passage of RBC through narrow capillaries and the reduction of blood viscosity under high shear rates. Although it has been substantial evidence that diabetes mellitus (DM) and hypercholesterolemia increase the risk of coronary heart disease, the mechanism is unclear. In this study the relationship between hemorheological parameters and plasma cholesterol in type 2 diabetic patients (n=55, mean age 43.4±9.2 years) was examined. Type 2 diabetic patients were classified as normocholesterolemic (n=25; cholesterol ≤ 200 mg/dl) and hypercholesteroloemic (n=30; cholesterol > 200 mg/dl) subgroups. Hypercholesterolemic type 2 diabetic …patients had the highest blood and plasma viscosity and the lowest RBC deformability. The results were significantly different from normocholesterolemic type 2 diabetic patients (p<0.001). Our data suggest that elevated plasma cholesterol may impair RBC deformability and increase in blood and plasma viscosity by an additional effect to hyperglycemia in type 2 diabetic patients. Show more

Keywords: Diabetes, erythrocyte deformability, blood viscosity, plasma viscosity, cholesterol

Citation: Clinical Hemorheology and Microcirculation, vol. 26, no. 4, pp. 257-263, 2002

Authors: Cefle, Kivanc | Tamer, Sule | Kaymaz, Alev A. | Balci, Merih | Ahmetov, Semiha | Palanduz, Sukru | Ozturk, Sukru | Salmayenli, Nihal | Onar, Vedat

Article Type: Research Article

Abstract: The effects of statins have been investigated mostly in hyperlipidemic states so far. We analysed blood cholesterol, triglyceride, albumin, fibrinogen and gammaglobulin levels, haematocrite, hemoglobin, erythrocyte, leukocyte and platelet counts, blood and plasma viscosity and erythrocyte rigidity in 12 rabbits fed on a normal diet (chow) which were given 1 mg/kg/day atorvastatin for 4 weeks. Compared to the baseline levels, erythrocyte rigidity (k=0.12±0.05 vs. k=0.7±0.02) and gammaglobulin levels (1.03±0.23 g/dl vs. 0.78±0.27 g/dl) decreased significantly (p=0.008 and p=0.025, respectively). Blood lipids, hematological variables, blood and plasma viscosity did not change statistically. Our findings imply that in a normolipemic state, statins …given in low doses may improve erythrocyte rigidity without altering blood lipids in short term. Decreased plasma gammaglobulin levels may be reflecting their immunomodulatory effects. Show more

Citation: Clinical Hemorheology and Microcirculation, vol. 26, no. 4, pp. 265-271, 2002

Authors: Bláha, M. | Skořepová, M. | Mašín, V. | Špásová, I. | Paráková, Z. | Malý, J. | Žák, P. | Belada, D. | Turková, A.

Article Type: Research Article

Citation: Clinical Hemorheology and Microcirculation, vol. 26, no. 4, pp. 273-275, 2002

Authors: Joern, H. | Kahn, N. | Baumann, M. | Rath, W. | Schmid‐Schoenbein, H.

Article Type: Research Article

Abstract: Various strategems of complexity analysis of microvascular blood flow were carried out in several fields of medicine in the past, as such as angiology, ophthalmology and neurology. The introduction of colour‐angio‐mode, a special form of colour coded Doppler sonography, now makes possible to perform complexity analysis of the placental blood displacement even in the absence of information about hydrodynamic details such as directionality, velocity profile and number of displaced blood cells. Algorithms were developed which allows to extract information concerning the time averaged power of phonon–erythrocytes collision events (from the square of the frequencies of back scattered ultrasound recorded during …166 ms) in 20,000 to 40,000 regions of interest. The obtained values are being displayed as false coloured pixels on a video‐screen, we succeeded to obtain quantitative data about displacement rates. In cross‐sectional and longitudinal studies we generated typical diagrams displaying the “occurrence rate” of various powers of displacement over time. By this mode of display contour plots can be generated, showing a large amount of low intensity pixels and a small amount of high intensity pixels representing the parenchymatous blood flow inside the placenta. As was to be expected, interdependencies between the placental blood flow and the maternal and fetal heart rates as well as the maternal breathing can be found. While there was only limited influence of maternal and fetal heart rate on the placental blood flow, maternal breathing showed striking influence. Surprisingly, during expiration the power of placental blood movement was decreased, and there was a marked increase during inspiration. In cases of severe intrauterine growth retardation, colour pixel intensities were seen to transiently vanish during end‐expiration. The power of placental blood displacement was marked increased subsequent to reducing maternal hematocrit during hemodilution therapy by infusion of artificial colloids. These interdependencies could be confirmed by ex vivo examinations perfusing and percolating the placenta after birth in a hemodynamic model. Additionally, we found interdependencies between fetal and maternal blood displacement inside the placenta. By modelling the decrease of fetal inotropic power in the ex vivo examinations, increase in the power of maternal blood displacement in the intervillous space. The two types of placental blood flow are known to be determined by many factors. While it is currently impossible to measure all these parameters determining an parenchymatous blood flow, it is possible to obtain useful informations about the physiologic and pathophysiologic changes of placental blood flow using colour‐angio‐mode as a tool of complexity analysis based on the distribution of local blood displacement. This new knowledge can help to understand clinically relevant changes in the individual patient as well their underlying causes. Show more

Keywords: Complexity analysis, colour‐angio‐mode, placental blood flow, pregnancy complication

Citation: Clinical Hemorheology and Microcirculation, vol. 26, no. 4, pp. 277-293, 2002

Article Type: Other

Citation: Clinical Hemorheology and Microcirculation, vol. 26, no. 4, pp. 295-299, 2002