Blood rheology associated with cardiovascular risk factors and chronic cardiovascular diseases: results of an epidemiologic cross-sectional study

Effect of Vibrotherapy on Body Fatness, Blood Parameters and Fibrinogen Concentration in Elderly Men

Elderly people need activities that will positively contribute to a satisfactory process of getting older. Vibration training uses mechanical stimulus of a vibrational character that, similarly to other forms of physical activity, affects metabolic processes and conditions of health. The aim of this work was to assess the influence of thirty vibration treatments on body fatness, hematologic and rheologic indexes of blood, and proteinogram and fibrinogen concentration in elderly men’s blood. The study included twenty-one males, aged 60–70 years (mean age 65.3 ± 2.7), who were randomly assigned into a vibrotherapy group (VG) and took part in interventions on mattresses generating oscillatory-cycloid vibrations, and a control group (CG), without interventions. In all patients the following assessments were performed twice: an assessment of body fatness using the bioimpedance method, a complete blood count with a hematology analyzer, and erythrocyte aggregation by a laser-optical rotational cell analyzer; whereas, total plasma protein and fibrinogen values were established, respectively, by biuret and spectrophotometric methods. In order to compare the impact of vibrotherapy on changes in the analyzed variables, analysis of variance (ANOVA) or the Wilcoxon test were used. After applying thirty vibration treatments in the VG, a significant decrease in body fatness parameters was confirmed: BM (∆BM: −2.7 ± 2.0; p = 0.002), BMI (∆BMI: −0.9 ± 0.7; p = 0.002), BF (∆BF: −2.5 ± 2.5; p = 0.013), and %BF (∆%BF: −2.0 ± 2.7; p = 0.041), as well as in RBC (∆RBC: −0.1 ± 0.1; p = 0.035). However, changes in erythrocyte aggregation and proteinogram were not confirmed. It was found that after thirty treatments with VG, a significant decrease of fibrinogen level took place (∆ = −0.3 ± 0.3, p = 0.005). Application of thirty vibrotherapy treatments positively affected body fatness parameters and fibrinogen concentrations in the examined. However, further research should include a greater number of participants.

Pediatric metabolic syndrome and cell blood counts: bivariate Bayesian modeling

Cell blood counts are components of hematological parameters and indicators of pro-inflammatory states. They are proposed to be associated with metabolic syndrome (MetS). This study aimed to assess the relationship of the white blood cell (WBC) and the red blood cell (RBC) counts with components of MetS in the pediatric age group. The sample consisted of 300 children (152 boys) aged 6-12 years. Hierarchical Bayesian analysis of the bivariate Poisson regression model was used to estimate the effect of various components of MetS according to the cell blood counts. We found that RBC and WBC counts were correlated with the fasting blood glucose, the waist-to-height ratio, serum triglycerides and the blood pressure levels adjusted for age, the body mass index, gender, total cholesterol, low-density lipoprotein cholesterol and the hip circumference. The high-density lipoprotein cholesterol was correlated with the RBC counts based on 95% high posterior density regions for parameters in the Bayesian model. Our findings may serve as confirmatory evidence for the beginning of inflammatory process related to the cardio-metabolic factors from early life.

Prognostic importance of hemoglobin in hypertensive patients with electrocardiographic left ventricular hypertrophy: the Losartan Intervention For End point reduction in hypertension (LIFE) study

BACKGROUND

The prognostic importance of hemoglobin is controversial. We investigated the prognostic importance of baseline and in-treatment hemoglobin in the LIFE study.

METHODS

Eight thousand one hundred ninety-four LIFE patients with hypertension and left ventricular hypertrophy with available baseline hemoglobin measurements were randomized to losartan- or atenolol-based treatment and followed for 4.8 years for end points of all-cause mortality and composite of cardiovascular death, nonfatal stroke, or nonfatal myocardial infarction.

RESULTS

U-shaped relations were observed between deciles of baseline hemoglobin and all-cause mortality and the composite end point. In univariate Cox models, baseline hemoglobin in the lowest gender-specific decile (women/men: <12.5/13.4 g/dL) was associated with all-cause mortality (hazard ratio [HR] 2.01, 95% CI 1.64-2.64) and the composite end point (HR 1.53, 95% CI 1.27-1.85, both P < .001), whereas hemoglobin in the highest gender-specific decile (women/men: > or =15.0/16.2 g/dL) was not. The decrease in hemoglobin was higher (P < .001) in patients allocated to losartan- (14.3-13.8 g/dL) versus atenolol-based treatment (14.3-14.0 g/dL). In Cox models with the same gender-specific definitions for high and low hemoglobin as time-varying covariates with adjustment for treatment allocation and established risk factors and diseases, hemoglobin in the lowest decile was associated with higher rates of all-cause mortality (HR 3.03, 95% CI 1.89-4.85, P < .001) and the composite end point (HR 1.36, 95% CI 1.08-1.71, P < .01), whereas hemoglobin in the highest decile was not.

CONCLUSIONS

After adjusting for other risk factors, relatively low, but not high, hemoglobin during antihypertensive treatment was associated with higher incidence of all-cause mortality and the composite end point.

Association between hematological parameters and metabolic syndrome components in a Chinese population

Insulin resistance, an essential core contributing to the metabolic syndrome (MS), has been demonstrated in some studies to be associated with white blood cell (WBC) or red blood cell (RBC) counts. The present study was undertaken to assess systemically the relationship between WBC or RBC counts and various clinical features of MS in a large Chinese population at Taiwan. A total of 4938 subjects (2891 men and 2047 women with a mean age of 50.1 +/- 12.6 years), who had attended health examination at this hospital were enrolled. The Adult Treatment Panel III (ATP III) definition of MS components was adopted in this study with the exception of the definition of obesity. This was defined as body mass index (BMI) greater than 27 kg/m(2). Overall, 14% had high serum total triglyceride (TG), 8% had low high-density lipoprotein (HDL) cholesterol, and 18% were obese. WBC counts showed a statistically significant (P < .001) correlation with TG (r = .265), HDL(r = -.187), fasting glucose (r = .084), and BMI (r = .172) but not with blood pressure levels. In addition, RBC counts correlated significantly (P < .001) with TG (r = .250), HDL(r = -.269), fasting glucose (r = .098), and BMI (r = .228). WBC and RBC counts in subjects grouped according to the presence of 0, 1, 2, and >or= 3 features of MS were 6268 +/- 1633, 6555 +/- 1782, 6995 +/- 1880, and 7185 +/- 1696 cells/mm(3), and 4.63 +/ -0.56 x 10(6), 4.73 +/- 0.54 x 10(6), 4.84 +/- 0.60 x 10(6), and 4.91 +/- 0.55 x 10(6) cells/mm(3), respectively (P for trend <.001). Subjects in the highest quartile of WBC or RBC counts demonstrated a three- or twofold increase, respectively, in the odds ratio for MS with 3 or more metabolic features compared to subjects in the lowest quartile of WBC or RBC counts. Increased WBC and RBC counts, albeit normal, were associated with a variety of MS features in a Taiwan Chinese population, suggesting that hematological parameters could potentially be used as indicators of this syndrome.

BLOOD FLOW SHEAR RATES IN ARTERIOLES OF SPONTANEOUSLY HYPERTENSIVE RATS AT EARLY AND ESTABLISHED STAGES OF HYPERTENSION

Alterations of blood rheological properties can affect blood flow shear rates and therefore alter changes in the interactions between blood and vascular wall components during the development of hypertension. This study was done to evaluate alterations of blood flow shear rates in resistance vessels during the development of genetic hypertension in rats. In the current study, measurements were carried out on spontaneously hypertensive rats (SHR) during an early (3 weeks of age) and an established stage (12 weeks of age) of hypertension development. Age matched normotensive Wistar Kyoto (WKY) rats were used as controls. Intravital television microscopy was used to quantitate blood flow shear rates in first-(1A), second-(2A) and third-order (3A) arterioles of the cremaster muscle. In the young SHRs mean arterial blood pressure was not different from age matched WKY rats, but there was a significant increase of shear rate values in all observed (1A, 2A, 3A) arterioles of SHRs. However, shear rate values were significantly less in arterioles (1A, 2A, 3A) of SHRs with an established hypertension compared to the 3-week-old SHR group. We conclude that shear rates are elevated in resistance vessels prior to an increase in mean arterial pressure during the development of genetic hypertension. These results suggest that a change in blood rheology may cause a change in peripheral vascular resistance and thus contribute to the pathogenesis of hypertension.

Platelet thrombus formation in microvessels of young spontaneously hypertensive rats

We have previously shown an increase in platelet-to-endothelial cell adhesion in microvessels of spontaneously hypertensive rats (SHR) during the established stage of hypertension (12 weeks). The objective of the current study was to determine if the platelet-to-endothelial cell interaction would be altered in the early developmental phase of hypertension. Male weanling (3 weeks old) SHRs (n=6) and age matched normotensive Wistar-Kyoto (WKY) rats (n=6) were used to study platelet thrombus formation. Intravascular fluorescein isothiocyanate tagged to bovine serum albumin was activated with 450-490 nm light to induce thrombus formation in microvessels. Plasma concentrations of von Willebrand factor (vWF), fibrinogen and fibronectin (FN) were measured in rats during both early (3 week) and established stages of hypertension development. Thrombus initiation time in both arterioles (847+/-85 sec) and venules (222+/-40 sec) of young SHRs was significantly shorter (p<0.05) than in arterioles (1270+/-88 sec) and venules (630+/-72 sec) of age matched WKY rats respectively. After thrombus appearance, however, overall time for vessel occlusion in arterioles (2590+/-90 sec) and venules (935+/-131 sec) of SHRs was not different compared to that in arterioles (2650+/-191 sec) and venules (1240+/-93 sec) of age matched WKY rats. The plasma concentration of FN was increased (p<0.05) in both the young (0.9+/-0.1 mg/ml) and mature (1.1+/-0.2 mg/ml) hypertensive rats (n=5) compared to that in young (0.6+/-0.03 mg/ml) and mature (0.5+/-0.1 mg/ml) WKY rats (n=5), while fibrinogen content (3.6 +/-0.3 mg/ml) was elevated (p<0.05) only in mature SHRs (n=5) compared to that (2.7+/-0.02 mg/ml) in age matched WKY rats (n=5). The plasma concentration of vWF was similar to that of controls in either age group of hypertensive animals. These results suggest that changes in platelet-to-endothelial cell interactions occur in the early phase of genetic hypertension development in rats, and appears to result from alteration of plasma concentration of adhesion proteins.

Increased erythrocyte aggregation in spontaneously hypertensive rats

Alterations of red blood cell (RBC) aggregation and plasma viscosity are major contributors to the changes in blood rheologic properties that cause an increase in peripheral vascular resistance during the development of hypertension. Although basic research and clinical study have provided considerable understanding of the pathophysiology of hypertension, the objective of this study was to determine whether an increase in RBC aggregability and plasma viscosity precede or accompany the development of high arterial blood pressure. To address this question, RBC aggregation and plasma viscosity were studied in spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto rats (WKY) at 3 and 12 weeks of age. The plasma concentrations of fibrinogen and fibronectin (FN) were also analyzed in both age groups. RBC aggregability and plasma viscosity were increased in both young and mature SHR compared to age-matched normotensive WKY rats. Mean arterial blood pressure and diastolic pressures were increased in mature hypertensive rats, whereas in young SHR only diastolic pressure was elevated significantly. The concentration of fibrinogen was higher only in the mature hypertensive rats, whereas plasma FN content was greater in both 3- and 12-week-old SHR compared to age-matched WKY. These results show the existence of increased RBC aggregability and plasma hyperviscosity not only during the established phase of hypertension, but also during the early stage of hypertension development, when mean arterial blood pressure is not yet significantly elevated in the genetically hypertensive rat model. These changes may be related to significant increase in the plasma protein FN, which occurs at the same time as the RBC aggregability and plasma viscosity changes. These results may increase attention to changes in the rheologic properties and to the mechanisms involved in these processes in the early stages of hypertension development.

Erythrocyte membrane cholesterol/phospholipid changes and hemorheological modifications in familial hypercholesterolemia treated with lovastatin

Fourteen patients with familial hypercholesterolemia treated with lovastatin (40 mg/day) for three months were studied to find out whether the expected changes in plasma lipids are accompanied by modifications in the lipid composition of the erythrocyte membrane and whether these in turn induce changes in the rheological behavior of the red blood cell. Our results demonstrate the efficacy of lovastatin in reducing the plasma concentration of cholesterol and LDL cholesterol. The changes observed in the plasma lipids correlate with a significant decrease in the cholesterol/phospholipid ratio of the red blood cell membrane, from 1.19 +/- 0.19 in a basal situation to 0.92 +/- 0.23 (p < 0.01) at the end of treatment. These changes in the lipid composition of the cell are statistically related to a decrease in erythrocyte aggregability and an improvement in blood filterability, which means beneficial change in the patients' hemorheological situation.

Does cholesterol depletion have adverse effects on blood rheology?

Blood viscosity (eta B) at shear rates 10 and 100s-1, plasma viscosity (eta P), hematocrit (Hct), and whole blood cholesterol (Chol) were measured in 50 patients with a history of myocardial infarction or unstable angina pectoris. Erythrocyte morphology was also studied by scanning electron microscopy to determine the proportion of nondiscocytic erythrocytes (NDE). There was a significant positive correlation between Chol and eta P (r = 0.41, P < 0.004) and a highly significant negative correlation (r = -0.69, P < 0.001) between Chol and Tk, a viscometric index of erythrocyte rigidity based on relative blood viscosity at high shear (eta B/eta P) corrected for Hct. This latter result indicates Chol reduction in this population may increase erythrocyte rigidity. Twenty-five patients with Chol values in the range 4.0-8.0 mmol/L were commenced on a standard lipid-lowering diet and after eight weeks half were also given pravastatin (40 mg daily). After thirty-two weeks Chol had fallen significantly more in the pravastatin group (28%) than in the diet only group (11%, P = 0.005). There was no change in eta P for either group but a significant increase in Tk for the pravastatin group only (P = 0.011). The change in total cholesterol (delta Chol) for each patient over thirty-two weeks was negatively correlated with both the change in the index of erythrocyte rigidity (delta Tk) (r = -0.40, P = 0.044) and the change in the proportion of nondiscocytic erythrocytes (delta NDE) (r = -0.47, P = 0.026). These data suggest that cholesterol reduction within the normolipemic range may be associated with unfavorable changes in blood rheology.

Hyperfibrinogenemia and hyperviscous plasma in hypertensive Africans

Changes in plasma fibrinogen concentrations (PFC) and relative plasma viscosity (RPV) were investigated in 61 Nigerian Africans while they were being treated for essential hypertension. The association of these hemorheologic variables with blood pressure was examined. An analogous study was done on 30 normotensive controls for comparison. The hypertensive patients had, overall, a significant increase in both PFC and RPV (p < 0.001) as compared with control values. However, 44.3% of the hypertensive patients had PFC and RPV values within the defined normal limits. This indicates that in a proportion of the hypertensives, treatment notwithstanding, PFC and RPV are altered only within the physiologic limits. Comparison of PFC and RPV with the degree of hypertension (mild: diastolic blood pressure (DBP) = 90mmHg; moderate: DBP = 91-99mmHg; severe: DBP > or = 100mmHg) showed significant stepwise increases at the moderate and severe levels as compared with the mild level of hypertension. The hyperfibrinogenemia and concomitant hyperviscous plasma observed in the present study could either play a role in the pathogenesis of the hypertension or be the consequence of the hypertension itself, at least in some patients.