Clinical Hemorheology and Microcirculation - Volume 7, issue 2
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Clinical Hemorheology and Microcirculation, a peer-reviewed international scientific journal, serves as an aid to understanding the flow properties of blood and the relationship to normal and abnormal physiology. The rapidly expanding science of hemorheology concerns blood, its components and the blood vessels with which blood interacts. It includes perihemorheology, i.e., the rheology of fluid and structures in the perivascular and interstitial spaces as well as the lymphatic system. The clinical aspects include pathogenesis, symptomatology and diagnostic methods, and the fields of prophylaxis and therapy in all branches of medicine and surgery, pharmacology and drug research.
The endeavour of the Editors-in-Chief and publishers of
Clinical Hemorheology and Microcirculation is to bring together contributions from those working in various fields related to blood flow all over the world. The editors of
Clinical Hemorheology and Microcirculation are from those countries in Europe, Asia, Australia and America where appreciable work in clinical hemorheology and microcirculation is being carried out. Each editor takes responsibility to decide on the acceptance of a manuscript. He is required to have the manuscript appraised by two referees and may be one of them himself. The executive editorial office, to which the manuscripts have been submitted, is responsible for rapid handling of the reviewing process.
Clinical Hemorheology and Microcirculation accepts original papers, brief communications, mini-reports and letters to the Editors-in-Chief. Review articles, providing general views and new insights into related subjects, are regularly invited by the Editors-in-Chief. Proceedings of international and national conferences on clinical hemorheology (in original form or as abstracts) complete the range of editorial features.
The following professionals and institutions will benefit most from subscribing to
Clinical Hemorheology and Microcirculation: medical practitioners in all fields including hematology, cardiology, geriatrics, angiology, surgery, obstetrics and gynecology, ophthalmology, otology, and neurology. Pharmacologists, clinical laboratories, blood transfusion centres, manufacturing firms producing diagnostic instruments, and the pharmaceutical industry will also benefit.
Important new topics will increasingly claim more pages of
Clinical Hemorheology and Microcirculation: the role of hemorheological and microcirculatory disturbances for epidemiology and prognosis, in particular regarding cardiovascular disorders, as well as its significance in the field of geriatrics. Authors and readers are invited to contact the editors for specific information or to make suggestions.
Abstract: The interpretation of the role of the hemorheological alterations in peripheral obliterative arterial diseases is still of considerable interest. After the first identification of the existence of a hyperviscosity condition in this disease, successive research has gradually tried to explain its meaning. First hyperviscosity was considered as associated to the disease, then some researchers have attributed it a decisive and essential role and have seen it capable, by itself, of reducing the blood supply to the tissue, while others have considered it just a subordinate expression of the disease. A last hypothesis tries to combine these two possibilities and considers…the hyperviscosity of vascular diseases first as dependent on the tissue ischemia and then as responsible for the activation of a vicious circle which further contributes to reduce the peripheral blood flow. In such interpretation the therapeutical attempts to treat the peripheral vascular diseases by means of the improvement of blood fluidity should assume a positive role.
Abstract: Research from many disciplines is coming together to give a more composite picture of the multitude of factors involved in cardiovascular and haematocrit control. In this review the term stress polycythaemia syndrome is used in its broadest sense, where all exogenous and endogenous stresses are considered. The contraction of plasma volume seen in association with the various stimuli is the end result of a final common pathway of neuroendocrine activation via the autonomic nervous system. In most circumstances the development of the stress polycythaemia syndrome is an appropriate response to a specific stimulus. However, there are haemorheological consequences which may…not always be advantageous and in the presence of vascular disease may predispose the subject to the possibility of arterial occlusion. Management of the stress polycythaemia syndromes depends on identification and removal of the stimuli and correction of the haemorheological disturbances.
Abstract: The role of blood rheology in retinal disorders is reviewed. Since retinal vessels can be observed directly, and capillary perfusion observed at fluorescein angiography, retinal studies have been of value in demonstrating the circulatory effects of overtly pathological blood rheology in haematological disorders, i.e. polycythaemias, paraproteinaemias, leukaemias and sickle cell disorders. Moreover, the susceptibility of the retinal circulation to arterial and venous occlusion, diabetic angiopathy, and increased intra-ocular pressure has revealed the potential of covertly pathological blood rheology to further impair blood flow and tissue function. In the compromised retinal circulation where shear forces are reduced, relatively small…increases in haematocrit, plasma viscosity, red cell aggregation and cell rigidity may be sufficient to reduce capillary perfusion and hence promote visual complications. Conversely, rheological therapy may be of value in these blinding disorders.
Abstract: Homozygous sickle cell (HbSS) disease is a clinical disorder characterized by abnormal hemorheology and a variety of pathophysiologic conditions; its underlying basis is a defect in the hemoglobin molecule which leads to polymer formation at low levels of oxygen tension. Micropipette analyses of oxygenated HbSS RBC indicate increased membrane elasticity and viscosity versus normal REC, especially for irreversibly sickled cells (ISC). HbSS RBC from a given donor are heterogeneous in their mechanical properties and large donor-to-donor variations are common. The abnormal rheological properties of HbSS blood become accentuated when oxygen tension is reduced, with micropipette data indicating an exponential increase…of effective membrane rigidity and the time constant for deformation as oxygen tension is lowered. However, for HbSS REC which remain discoidal and for all normal RBC, no effects of oxygen tension are observed. Presently, correlations between rheologic measurements and clinical severity are less than satisfactory, perhaps due to the hemorheological tests employed; suggestions for alternate rheologic techniques and a brief review of therapeutic approaches are presented.
Keywords: SS Disease, Rheology, Erythrocyte mechanics, ISC, Oxygen tension
Abstract: Red cell “flexibility”, generally accepted as a pivotal determinant of blood flow in the microvessels, represents the micromechanical “behavior” of a complex structure consisting in a viscoelastic membrane shell and a cytosolic fluid. It is impossible to describe its overall “material properties” in the sense of physical “constants”; only its behavior can be tested in fluid dynamic conditions kept as constant and well controlled as possible. Under such conditions, an overt abnormal flow behavior can easily be diagnosed. Earlier claims of “covertly abnormal red cell flow behavior” in diabetes mellitus, which were based on measurements of “more rigid” than normal…cells have recently been contradicted, the earlier results being attributed to technological or to contamination errors (by the presence of white cells). New data obtained by techniques inherently independent of leukocyte artefacts are reviewed: various types of the “single erythrocyte rigidometer” (SER), polymicroviscometry (PMV) of packed red cells, MyNiPore microsieve conductometry (MMC) and whole blood viscometry. All data reviewed clearly confirm the presence, in certain diabetic patients, of microrheologically abnormal erythrocytes. The reason for the failure of conventional techniques to detect these abnormalities is discussed.
Keywords: diabetes mellitus, diabetic neuropathy, diabetic retinopathy, Dintenfass Tk-value, leukocyte artefacts, polymicroviscometry, MyNiPore microsieves, MyNiPore microsieve conductometry, red cell “deformability”, red cell filtrometry, single erythrocyte rigidometry
Abstract: Patients with diabetes mellitus develop hyperproteinaemia with a consequential increase in erythrocyte aggregation and blood viscosity. Evidence for a loss of erythrocyte deformability is more controversial, however, with steady-state diabetics showing largely normal rheology when studied by micropipette, ektacytometric, or filtration techniques. Decompensated diabetics with hyperosmolar plasma or a very high intraerythrocytic sorbitol concentration may, however, have impaired erythrocyte deformability. Membrane studies of erythrocytes from diabetics have shown insulin-dependent abnormalities of lipid fluidity, cholesterol/phospholipid ratio, and Na+ /K+ ATPase activity but most of the rheological methods used in clinical studies are not yet sufficiently sensitive or specific to assess…the rheological consequences of these membrane changes.
Abstract: In ten POAD patients, 800 mg. of Defibrotide (polideoxynucleotide extracted from mammalian lung, with antitrombotic and fibrinolytic activity) were infused i.v. Blood and plasma viscosity, haematocrit, blood filterability and fibrinogen concentration were controlled, in basal conditions and after one hour from the end of infusion. Haemodynamic parameters: rest flow, peak flow, time to peak flow, half time and total time of reactive hyperemia by means of strain gauge pletismography, were controlled at lower limbs before infusion and after 1 h., 2 h., 6 h., from the end of infusion. The present investigation showed an improvement of rheological parameters and a…decrease of total time and half time of reactive hyperemia. These data demonstrate a rheological activity of Defibrotide as well as the fibrinolytic one.
Abstract: Twenty patients suffering from peripheral obliterative arterial disease underwent metabolic and haemorheological study. The femoral arteriovenous differences in lactate and oxygen extraction varied with the severity of the ischemic process, as assessed clinically. In patients with claudication lactate release and oxygen extraction were comparable with those in the control group while were significantly increased in Fontaine’s III and IV stage patients. Moreover this latter group showed the most relevant changes in whole blood viscosity and filterability. Such findings bring a further contribution to the correlation between the regional circulatory imbalance and changes in haemorheological parameters.
Keywords: Hyperviscosity, Peripheral Ischemia, Vascular Disease, Oxygen Transport