Clinical Hemorheology and Microcirculation - Volume 21, issue 3-4

Article Type: Other

Citation: Clinical Hemorheology and Microcirculation, vol. 21, no. 3-4, pp. 155-155, 1999

Authors: Pirrelli, Anna

Article Type: Research Article

Abstract: The strong relationship between arterial hypertension and hemorheological alteration present in all the vascular segments can be affirmed. These hemorheological changes are: an increase in the whole blood and plasma viscosity, in red blood cell (RBC) rigidity and aggregability and subsequently a decrease in oxygen delivery. Anyway, there are very interesting, still now unclear questions to be resolved: Can arterial hypertension (with its vascular and cardiac remodeling) be the most relevant factor inducing alterations in the macro and the microrheology? Can the altered hemorheology, above all in the microcircle, be one of the numerous causes …of hypertension? What is the influence of tissue oxygenation changes in these situations: are these changes or effects of alterations during hypertension? In the next years using new technologies we hope that these problems will be resolved indicating new ways to treat hypertensives and to present its related complications. Show more

Keywords: Hypertension, hemorheology, atherosclerosis

Citation: Clinical Hemorheology and Microcirculation, vol. 21, no. 3-4, pp. 157-160, 1999

Authors: Suzuki, Hidekazu | Suematsu, Makoto | Schmid‐Schönbein, Geert W.

Article Type: Research Article

Abstract: The mechanisms that lead to organ injury in hypertension are incompletely understood. In particular, there is a lack of evidence that serves to link the elevation of arterial blood pressure with end organ damage. Experimental models of hypertension have a range of microvascular abnormalities in addition to a shift in blood pressure. There is evidence for an oxidative stress in microvascular endothelium derived from xanthine and NADPH oxidase. Furthermore, there exists an immune suppression accompanied by abnormally elevated circulating leukocyte counts, depression of selectin membrane adhesion to the endothelium and enhanced cell apoptosis. Many of the deficiencies in the spontaneously …hypertensive rats can be corrected by adrenalectomy, suggesting a contribution of glucocorticoids to the abnormalities in this model. These observations suggest a significantly enhanced vascular oxidative stress which is accompanied by a frustrated inflammatory response due to a glucocorticoid dependent deficiency of leukocyte adhesion to vascular endothelium. Show more

Citation: Clinical Hemorheology and Microcirculation, vol. 21, no. 3-4, pp. 161-168, 1999

Authors: Cicco, G. | Pirrelli, A.

Article Type: Research Article

Abstract: Arterial hypertension could be considered a progressive ischaemic syndrome interesting the macro and the microcirculation. In order to improve the clinical and therapeutic approach to the treatment of arterial hypertension, research has centered on blood flow to evaluate the different components and their very intricate relationships influencing the micro‐ and the macrocirculation. Of course the main problem is to study the link between the blood flow and the peripheral tissue oxygenation. During hypertension very important alterations in rheological, mechanical and biochemical characteristics of erythrocytes and of blood flow have been shown. It is very relevant the increase in blood viscosity, …the decrease in red blood cell (RBC) deformability, the formation of RBC “rouleaux” and RBC aggregates. These hemorheological determinants can favour an increase of peripheral resistances and of arterial blood pressure, causing or worsening hypertension, a decrease in oxygen transport to tissue and peripheral perfusion, a decrease of the active exchange surface area in the microvasculature, especially in complicated hypertension. We have studied 320 patients: 123 with Essential Hypertension (EH) (M 59, F 64 aged 50 \pm 25 years); 81 with Secondary Hypertension (SH) without associated other pathologies influencing hemorheology (M 42, F 39 aged 48 \pm 20 years); 116 SH with other pathologies or conditions associated influencing hemorheology such as: diabetes, lipoidoproteinosis, obesity, smoking, HD, elderly, etc. (M 48, F 68 aged 46 \pm 20 years). Using a Laser‐assisted Optical Rotational Red Cell Analyzer (LORCA) acc. to Hardeman (1994) we studied Elongation Index (EI) and aggregation kinetics of red blood cells in these patients. We also evaluated TcpO_{2} and TcpCO_{2} using a transcutaneous oxymeter (Microgas 7650, Kontron Instruments). In hypertensives we found a decrease in erythrocyte deformability (evaluated with EI), in erythrocyte aggregation time, a fibrinogenaemia increase, an increase of shear rate to disaggregate erythrocytes, a decrease in cellular oxygen delivery and tissue oxygenation, an impairment of microcirculation. These changes may be involved in the development of arterial hypertension and in its pathogenesis. These patterns also are more impaired in hypertensives with diabetes, lipoidoproteinosis, etc. These patterns are not related with the age of the patients but they are significantly and directly related (p<{} 0.01) with the patient hypertension‐age. This could be a new way to realize a better treatment in hypertensives and a prevention of cardiovascular complications (i.e.: myocardial infarction, TIA, etc.). Show more

Keywords: Hemorheology, hypertension, LORCA, tissue oxygenation

Citation: Clinical Hemorheology and Microcirculation, vol. 21, no. 3-4, pp. 169-177, 1999

Authors: Sandhagen, B.

Article Type: Research Article

Abstract: Rheological findings in essential hypertension are increases in haematocrit, plasma fibrinogen, plasma and whole blood viscosity, and erythrocyte aggregability as well as impaired erythrocyte deformability. Are these abnormalities secondary effects of an increased blood pressure via an increased filtration pressure rendering haemoconcentration or is the initial pressure‐increase the result of a deterioration of any of the rheologic variables? Since the diameter of the red cell is about 8.5 \mu m, and that of the smallest capillaries about 3 \mu m, the ability of the cell to deform is of vital importance for capillary flow, and a decreased erythrocyte …deformability could cause an increased microvascular flow resistance. We found a negative correlation between erythrocyte deformability and fasting insulin and also a decreased erythrocyte deformability in hypertensive patients during a 2 h euglycaemic insulin clamp. Associations between increased intracellular Ca^{2+} and decreased erythrocyte deformability on one hand and between in vitro insulin and an accumulation of Ca^{2+} in red blood cells on the other have earlier been shown. Hence, a decreased insulin sensitivity might be one important factor in the development of hypertension acting via an impaired erythrocyte deformability and an increased flow resistance in the microcirculation. Show more

Keywords: Hypertension, insulin sensitivity, erythrocyte deformability

Citation: Clinical Hemorheology and Microcirculation, vol. 21, no. 3-4, pp. 179-181, 1999

Authors: Rampling, M.W.

Article Type: Research Article

Abstract: Patients suffering from diabetes or hypertension commonly exhibit increased blood viscosity compared with healthy controls. This is primarily the result of elevated plasma fibrinogen concentration. Cigarette smokers also exhibit raised blood viscosity but in their case the main cause is a raised haematocrit. In this paper the effects of concurrent hypertension, diabetes and cigarette smoking on blood viscosity is reviewed. Evidence is presented that the haemorheological disturbances associated with each of these modalities are additive when present together in a subject.

Keywords: Haemorheology, fibrinogen, blood viscosity, plasma viscosity, hypertension, diabetes, smoking

Citation: Clinical Hemorheology and Microcirculation, vol. 21, no. 3-4, pp. 183-187, 1999

Authors: Yedgar, S. | Hovav, T. | Barshtein, G.

Article Type: Research Article

Abstract: Red blood cell (RBC) intercellular interactions, i.e., self‐aggregation and adherence to endothelial cells (EC), play important roles in microcirculation. These RBC flow properties are determined by cell membrane components, which are prone to damaging reactive oxygen species (ROS) produced in oxidative stress (OS) states. Alterations in RBC aggregability and adherence have been linked to the pathophysiology in numerous diseases associated with OS. We investigated RBC intercellular interactions in four OS states – thalassemia, treatment of RBC with phenyl‐hydrazine or H_{2} O_{2} , and photodynamic virus inactivation of blood units. All these OS states increased RBC adherence to EC, …but only part of them elevated their aggregability, while others abolished it. It is proposed that (1) different OS states might induce disparate effects on RBC intercellular interactions; (2) RBC aggregability and adherence to EC, although both intercellular interactions, are controlled by different cell surface factors. Show more

Keywords: Oxidative stress, erythrocytes, aggregability, adherence to endothelial cells

Citation: Clinical Hemorheology and Microcirculation, vol. 21, no. 3-4, pp. 189-193, 1999

Authors: Meiselman, Herbert J.

Article Type: Research Article

Abstract: The serious pathophysiologic consequences of systemic hypertension have prompted numerous basic science and clinical studies related to cardiac or vascular abnormalities. More recently, hemorheologic alterations in hypertension have been explored in an attempt to determine the import of rheologic factors vis‐à‐vis the elevated total peripheral resistance observed in hypertensive patients. To date, various studies have documented several abnormalities (e.g., increased blood and plasma viscosity, elevated hematocrit), with some suggesting altered RBC or WBC rigidity. However, there is much less information relevant to the “chicken or egg” problems: (1) are reported hemorheological abnormalities the cause or the result of hypertension; (2) …does normalization of blood pressure also normalize hemorheological parameters? In overview, the current literature indicates that hemorheology and hypertension may be linked, but that the details of this association and its cause‐effect relations remain unclear. Show more

Citation: Clinical Hemorheology and Microcirculation, vol. 21, no. 3-4, pp. 195-200, 1999

Authors: Stoltz, J.F. | Zannad, F. | Kdher, Y. | Le Bray Des Boses, B. | Ghawi, R.E. | Meilhac, B. | Cauchois, G. | Gentils, M. | Muller, S.

Article Type: Research Article

Abstract: Beyond their effects on blood pressure, antihypertensive agents may produce additional effects on blood rheology and arterial compliance abnormalities which may play a role in the target organ damage. These effects may depend only on their specific pharmacological properties. We compared the effects of nitrendipine to hydrochlorothiazide in 33 mild to moderate hypertensives in a double blind parallel group trial. Blood rheology and radial artery diameter and compliance were measured at t= o and t= 2 months. Both drugs produced blood pressure lowering. Blood viscosity decreased in the nitrendipine group and increased in the hydrochlorothiazide patients. Red blood …cells deformability increased only in the nitrendipine group. Radial artery diameter and compliance were not different between the two groups but there was a trend to an increase of the cross‐sectional compliance in hydrochlorothiazide group and to a decrease in nitrendipine group. Our data show that a calcium antagonist (Nitrendipine) could improve rheological parameters. Show more

Keywords: Hypertension, blood and plasma viscosity, RBC aggregation, arterial compliance, calcium antagonist, diuretic

Citation: Clinical Hemorheology and Microcirculation, vol. 21, no. 3-4, pp. 201-208, 1999

Authors: Toth, K. | Kesmarky, G. | Vekasi, J. | Nemes, J. | Czopf, L. | Kapronczay, P. | Halmosi, R. | Papp, E. | Juricskay, I.

Article Type: Research Article

Abstract: Hemorheological factors play an important role in the pathogenesis of different cardiovascular diseases. The hemorheological and hemodynamic parameters in essential hypertension and their possible modification by antihypertensive treatment were examined in the following two studies. In the first study the fundus appearance and hemorheological parameters (plasma and whole blood viscosity (WBV), fibrinogen level) of 33 hypertensive patients (mean age: 55 years) were examined. The fundus appearance showed retinopathy in all the cases between stages I–III. All the measured hemorheological parameters of the examined patients were in the pathological range (WBV at 90 s^{-1} : 5.18 mPa s) and …were significantly (p<{} 0.01) higher than in healthy controls (WBV at 90 s^{-1} : 4.18 mPa s). The hemorheological factors showed a parallel deterioration with the fundus appearance, namely their values were significantly (p<{} 0.01) higher in patients with a fundus appearance stage III (WBV at 90 s^{-1} : 6.02 mPa s) than stage I (WBV at 90 s^{-1} : 4.51 mPa s). These results show that there is a correlation between hemorheological parameters and fundus appearance in hypertensives, and this suggests that hemorheological factors may play a role in the development of hypertensive retinopathy. In the second study the hemorheological and hemodynamical effects of Doxazosin, a selective alpha‐1‐adrenoreceptor blocker agent, was examined in twenty patients (mean age: 54 years) with essential hypertension. Hemorheologic (hematocrit, fibrinogen, plasma and whole blood viscosity) and hemodynamic (cardiac output and index, total peripheral resistance) parameters and plasma lipids were determined. The measurements were carried out before the beginning of the treatment, after 1 week and after 12 weeks treatment periods. Besides significant reduction of blood pressure and total peripheral resistance (p<{} 0.001), a decrease in cholesterol (p<{} 0.001) and triglycerides (p<{} 0.01) levels and a beneficial effect on hemorheological parameters was detected. Fibrinogen and plasma viscosity decreased significantly (p<{} 0.01). Hematocrit value was also lower after one week (p<{} 0.001), then an increase could be seen. Whole blood viscosity showed similar changes as hematocrit, but the degree of its final increase was slighter, which was supported by the significantly lower value of corrected blood viscosity (p<{} 0.05). All these findings indicate that hemorheological factors may play a role in the pathogenesis and in the development of organ damages in hypertension. Show more

Keywords: Hypertension, hypertensive retinopathy, blood rheology, cardiovascular diseases, drug treatment

Citation: Clinical Hemorheology and Microcirculation, vol. 21, no. 3-4, pp. 209-216, 1999