Association of plasma viscosity and carotid thickening in a French working cohort

Calculated whole blood viscosity in non-diabetic subjects with asymptomatic carotid atherosclerosis: How insulin resistance may affect blood viscosity

BACKGROUND AND OBJECTIVE

Asymptomatic atherosclerosis is an important early marker of vascular damage and, among its risk factors, hemorheological alterations play an important role.

PATIENTS AND METHODS

In a cohort of 85 non-diabetic subjects with asymptomatic carotid atherosclerosis (ACA), we have measured whole blood viscosity (cWBV) according to the haematocrit and plasma fibrinogen level. The cWBV distinguish the subgroup of ACA subjects with 3-5 cardiovascular risk factors (CRFs) from that with 1-2 CRFs and the same behavior is present for haematocrit and plasma fibrinogen level. Therefore, we divided the whole group of ACA subjects according to the medians of the four surrogate indexes with an insulin resistance degree of TG/HDL-C, TyG, VAI and LAP.

RESULTS

The analysis of the correlation between cWBV and each index of insulin resistance has shown that no correlation is present in the whole group and in the group of ACA subjects with 1-2 CRFs, while in the subgroup with 3-5 CRFs there is a positive correlation between cWBV with TG/HDL-C and TyG at a low degree of statistical significance.

CONCLUSIONS

The date underline that subjects with this clinical condition have an unaltered evaluation of the cWBV compared to the other indices.

An assessment of the hemorheological profile in patients with subclinical carotid atherosclerosis divided in relation to the number of cardiovascular risk factors and different degrees of insulin resistance

We present a cohort of 100 subjects [43 men and 57 women; median age 66.00(25)] who were tested using carotid ultrasound to identify subclinical carotid atherosclerosis (SCA). We have evaluated the behaviour of whole blood viscosity (WBV) at high (450 s-1) and low (0.51 s-1) shear rates, plasma viscosity (450-1), hematocrit and mean erythrocyte aggregation. When compared to normal control subjects, using the Mann-Whitney test, we observed in SCA patients a significant increase in WBV only. The results were substantial after having divided the SCA subjects according to the cardiovascular risk factors (CRFs) and the degree of insulin resistance; the research was performed using two surrogate indexes such as TG/HDL-C and TyG. With the division carried out according to CRFs, employing the Kruskal-Wallis test, results show a significant increase in WBV (at high and low shear rates), in plasma viscosity, in erythrocyte aggregation and plasma fibrinogen level. Whereas by dividing them into the median of TG/HDL-C and TyG, we noticed a significant increase in WBV (at high and low shear rates) and in erythrocyte aggregation in the two groups with high TG/HDL-C ratio and with high TyG; having found an increased level of plasma fibrinogen in the latter. The data underlines the role of the main hemorheologic aspects in subclinical carotid atherosclerosis being closely correlated to the CRFs and different degrees of insulin resistance.

The Relationship Between Plasma Whole Blood Viscosity and Cardiovascular Events in Patients With Chronic Kidney Disease

BACKGROUND

Plasma levels of estimated whole blood viscosity (eWBV) have been increased by endothelial inflammation. Because there were no consistent data for assessing the eWBV levels for prediction of cardiovascular event (CVE) in patients with chronic kidney disease (CKD). We aimed to investigate the relationship between plasma eWBV levels and CVEs in patients with CKD.

MATERIALS AND METHODS

We conducted a prospective, cross-sectional, long-term follow-up study, assessing the relationship between plasma eWBV levels and CVE (either fatal or nonfatal) in patients with newly diagnosed CKD. We also evaluated estimated glomerular filtration rate (eGFR), pentraxin 3 (PTX3), high-sensitivity C-reactive protein (hsCRP), and flow-mediated dilatation (FMD).

RESULTS

Study patients were divided into 2 groups: patients with CVE and patients without CVE. The eWBV levels were higher in patients with CVE. Additionally, PTX3 and hsCRP were higher, and FMD and eGFR were lower in patients with CVE compared to those without CVE. According to the Cox regression analysis, WBV, plasma asymmetric dimethylarginine levels, FMD, hsCRP, eGFR, systolic blood pressure, calcium, and history of diabetes were independent predictors of CVEs in patients with CKD. Kaplan Meier survival curves were generated to establish the impact of the WBV on the cumulative survival of the cohort. Patients with eWBV values higher than 5.2 centipoise (cP) had lower survival rates when compared to patients with eWBV values lower than 5.2 cP (log rank = 4.49 df = 1 P = .034).

CONCLUSION

In conclusion, plasma eWBV levels may increase the presence of lower eGFR and affect CVE in patients with CKD independent of classical and unconventional risk factors.

Coronary Microvascular Function and Beyond: The Crosstalk between Hormones, Cytokines, and Neurotransmitters

Beyond its hemodynamic function, the heart also acts as a neuroendocrine and immunoregulatory organ. A dynamic communication between the heart and other organs takes place constantly to maintain cardiovascular homeostasis. The current understanding highlights the importance of the endocrine, immune, and nervous factors to fine-tune the crosstalk of the cardiovascular system with the entire body. Once disrupted, this complex interorgan communication may promote the onset and the progression of cardiovascular diseases. Thus, expanding our knowledge on how these factors influence the cardiovascular system can lead to novel therapeutic strategies to improve patient care. In the present paper, we review novel concepts on the role of endocrine, immune, and nervous factors in the modulation of microvascular coronary function.

Decreased wall shear stress in the common carotid artery of patients with peripheral arterial disease or abdominal aortic aneurysm: Relation to blood rheology, vascular risk factors, and intima-media thickness

BACKGROUND

Wall shear stress, a local risk factor of atherosclerosis, is decreased in the common carotid artery of patients with vascular risk factors. We evaluated wall shear stress in the common carotid artery of patients with symptomatic peripheral arterial occlusive disease (PAD) and abdominal aortic aneurysm (AAA). As blood viscosity is a determinant of wall shear stress, we further investigated the impact of rheologic variables on wall shear stress in relation to vascular risk factors and intima-media thickness.

METHODS

High-resolution ultrasonography scans were used to study intima-media thickness, internal diameter, and blood velocity in the common carotid artery of 31 patients with PAD, 36 patients with AAA, and 37 controls. Furthermore, major hemorheologic variables and vascular risk factors were evaluated, and wall shear stress was calculated.

RESULTS

Wall shear stress was lower in patients with PAD (median [IQR], dynes/cm(2): 14.4 [10 to 19]) and with AAA (12.1 [9 to 15]) than in healthy controls (20.6 [17 to 24]; P < .0001). Wall shear stress was inversely related to red cell aggregation (P = .01), fibrinogen (P = .003), leucocyte count (P = .001), plasma viscosity (P = .04), and intima-media thickness (P < .0001). Furthermore, wall shear stress was negatively associated with age, smoking, and triglycerides, but positively correlated with high-density lipoprotein cholesterol (all P < .001). When the influence of all these predictors were simultaneously taken into account in a multiple regression model, only age (P < .0001), smoking (P = .005), and triglycerides (P = .003) remained significantly associated with wall shear stress.

CONCLUSIONS

This is the first report, to our knowledge, showing that wall shear stress of the common carotid artery is decreased in patients with symptomatic PAD and in patients with AAA. Rheologic variables are less important in predicting wall shear stress than age, triglycerides, and smoking.

Association of hyperviscosity and subclinical atherosclerosis in obese schoolchildren

Since December 2001, a total of 52 obese schoolchildren and 38 non-obese controls have undergone vascular ultrasound at our institution. From this cohort, we enrolled 40 obese children (16 girls, median age 12 years, mean body mass index (BMI) 27.5+/-4.6 kg/m2) and 26 non-obese peers (12 girls, median age 12 years, mean BMI 16.1+/-2.4 kg/m2) for the present study. We analysed the association between obesity, subclinical atherosclerosis and haemorheological variables, including whole blood viscosity (WBV) at four different shear rates (200 s-1, 30 s-1, 5 s-1 and 1 s-1), plasma viscosity, and serum lipid concentrations. Blood lipids and apolipoproteins were also determined and correlated with carotid intima-media thickness (IMT) and flow-mediated dilatation (FMD) of the brachial artery, measured by high-resolution ultrasonography. WBV at 200 s-1, 30 s-1 and 5 s-1, as well as plasma viscosity, were significantly higher in the obesity group (all P <0.01). No difference was seen for WBV at 1 s-1, erythrocyte aggregation and haematocrit. WBV at high shear rates was significantly associated with BMI, increased IMT and decreased FMD ( P <0.05). After controlling for BMI on stepwise linear regression, WBV at 30 s-1 was the strongest predictor of IMT ( P < 0.01) and FMD ( P < 0.05) among our study variables.

CONCLUSION

Hyperviscosity is related to subclinical atherosclerosis in obese schoolchildren. Viscosity parameters contribute new information in addition to body mass index, blood pressure and blood lipids and may help to facilitate risk stratification in obese paediatric patients.

Reversal of left ventricular hypertrophy: what have recent trials taught us?

Regression of left ventricular hypertrophy (LVH) is an important intermediate target for antihypertensive therapy. Thus, several trials and meta-analyses have attempted to compare the effects of different antihypertensive agents on LVH, but flawed study designs and methodologic problems have limited the utility of these studies. PRESERVE (Prospective Randomized Enalapril Study Evaluating Regression of Ventricular Enlargement), LIVE (LVH: Indapamide Sustained Release Versus Enalapril) and LIFE (Losartan Intervention For Endpoint reduction in hypertension) represent a new generation of large well designed trials with the power to compare different antihypertensive drugs. These studies have shown that treatment regimens based on enalapril and a nifedipine gastrointestinal therapeutic system are of similar efficacy (PRESERVE), that indapamide sustained release (SR) is superior to enalapril (LIVE), and that a regimen based on losartan is superior to a regimen based on atenolol (LIFE) in reversing hypertensive LVH. LIVE incorporated on-treatment echocardiographic quality control, with centralized readers blinded for both treatment and sequence of recording. The findings of these rigorous studies, to some extent in disagreement with results of previous meta-analyses, support the notion that antihypertensive drugs need to be judged on their individual effects on important intermediate endpoints such as LVH in well designed and adequately sized studies. However, extrapolation of the results of these studies in terms of class effects could be misleading and should be made with caution.

Early-onset carotid atherosclerosis is associated with increased intima-media thickness and elevated serum levels of inflammatory markers

BACKGROUND AND PURPOSE

Several factors have been held responsible for the development of atherosclerosis. To avoid the masking effect of age, we evaluated correlates of carotid atherosclerosis in patients <55 years of age.

METHODS

Plasma lipids, oxidative resistance of low-density lipoprotein, homocysteine, inflammatory markers, plasma viscosity, and red cell deformability were measured in fasting blood samples of 100 subjects: 45 patients with >30% stenosis of the internal carotid artery, 20 patients with carotid occlusion, and 35 control subjects. Stenosis and intima-media thickness (IMT) of the carotid artery were evaluated by duplex ultrasound.

RESULTS

White blood cell (WBC) count, plasma fibrinogen, C-reactive protein (CRP), and lipoprotein(a) levels were significantly higher in patients than in control subjects, and patients had increased IMT (P<0.01 for all comparisons). There was a tendency for higher homocysteine levels in patients. Smokers had higher WBC, fibrinogen, and CRP levels. After the effect of smoking was controlled for, WBC count, natural logarithmic transform of homocysteine, and online-measured IMT remained significantly higher in patients than in control subjects. WBC, fibrinogen, and CRP levels were highest in the highest IMT quartile (P=0.012, P=0.007, and P=0.036, respectively).

CONCLUSIONS

Inflammatory markers and homocysteine have a more important role than lipid factors in early-onset carotid atherosclerosis. We cannot recommend the measurement of low-density lipoprotein peroxidation as a routine screening test to identify high-risk patients for early-onset carotid atherosclerosis. The confounding effect of smoking on inflammatory markers should be considered in studies on atherosclerosis.

Intima-media thickness: a new tool for diagnosis and treatment of cardiovascular risk

Increased intima-media thickness (IMT) is a non-invasive marker of early arterial wall alteration, which is easily assessed in the carotid artery by B-mode ultrasound, and more and more widely used in clinical research. Methods of IMT measurement can be categorized by two approaches: (i) measurement at multiple extracranial carotid sites in near and far walls and (ii) computerized measurement restricted to the far wall of the distal common carotid artery. Because IMT reflects global cardiovascular risk, its normal value might be better defined in terms of increased risk rather than in terms of statistical distribution within a healthy population. The available epidemiological data indicate that increased IMT (at or above 1 mm) represents a risk of myocardial infarction and/or cerebrovascular disease. Close relationships have been shown between: (i) most traditional cardiovascular risk factors; (ii) certain emerging risk factors such as lipoproteins, psychosocial status, plasma viscosity, or hyperhomocysteinemia; and (iii) various cardiovascular or organ damages such as white matter lesion of the brain, left ventricular hypertrophy, microalbuminuria or decreased ankle to brachial systolic pressure index. Thus, IMT gives a comprehensive picture of the alterations caused by multiple risk factors over time on arterial walls. Prospective primary and secondary prevention studies have also shown that increased IMT is a powerful predictor of coronary and cerebrovascular complications (risk ratio from 2 to 6) with a higher predictive value when IMT is measured at multiple extracranial carotid sites than solely in the distal common carotid artery. Therapeutic double-blind trials have shown that lipid-lowering drugs, such as resin and overall statines, and to a lesser extent antihypertensive drugs, such as calcium antagonists, may have a beneficial effect on IMT progression in asymptomatic or in coronary patients. However, methodological standardization of IMT measurement still needs to be implemented before routine measurement of IMT can be proposed in clinical practice as a diagnostic tool for stratifying cardiovascular risk in primary prevention and for aggressive treatment decision. It can be anticipated however, that the presence of increased carotid IMT in one individual with intermediate cardiovascular risk would lead to his classification into the high-risk category and thus influence the aggressiveness of risk factor modifications.