Blood viscosity and its relationship to iron deficiency, symptoms, and exercise capacity in adults with cyanotic congenital heart disease.

OBJECTIVES: This study sought to determine the relationship between blood viscosity and iron deficiency and their impact on symptoms and exercise function in adults with cyanotic congenital heart disease. BACKGROUND: Iron deficiency is believed to raise whole blood viscosity in cyanotic congenital heart disease, although available data are inconsistent. METHODS: Thirty-nine cyanotic adults were prospectively assessed for iron deficiency (transferrin saturation < or =5%), hyperviscosity symptoms, and exercise capacity. Same-day measurement of whole blood viscosity and hematocrit (Hct) adjusted viscosity (cells resuspended in autologous plasma to Hct of 45%) was performed at shear rates ranging from 0.277 s(-1) to 128.5 s(-1). RESULTS: Viscosity did not differ between patients with iron deficiency (n = 14) and those without (n = 25). Whole blood viscosity correlated with Hct (r = 0.63, p < 0.001 at low shear and r = 0.84, p < 0.001 at high shear) but not with red blood cell size or iron indices. Hyperviscosity symptoms were independent of iron indices but directly correlated with increased Hct-adjusted viscosity (r = 0.41, p = 0.01). Exercise capacity did not differ in iron-deficient patients. However, peak oxygen consumption was higher in those with Hct > or = 65% (12.6 +/- 3.4 ml/kg/m2 vs. 9.8 +/- 2.6 ml/kg/m2, mean +/- SD, p = 0.036) despite higher whole blood viscosity in these same individuals (p < 0.01 for all shear rates). CONCLUSIONS: Iron deficiency is common in cyanotic adults but does not alter viscosity. Hyperviscosity symptoms are associated with a higher Hct-adjusted viscosity independent of cell size or iron stores. Higher Hct is associated with better exercise capacity. Further work to understand the origin of hyperviscosity symptoms is warranted.

Haemorheology in Gaucher disease.

UNLABELLED: In Gaucher disease, a deficiency of glucocerebrosidase results in the accumulation of glucocerebroside within the lysosomes of the monocyte-macrophage system. Prior to the availability of enzyme replacement therapy (ERT), splenectomy was often indicated for hypersplenism. Haemorheological abnormalities could be expected in view of the anaemia and abnormal lipid metabolism in these patients and the role of the spleen in controlling erythrocyte quality. OBJECTIVES: To investigate the effect of Gaucher disease on blood and plasma viscosity, erythrocyte aggregation and erythrocyte deformability, and to determine whether observed rheological differences could be attributed to splenectomy. METHODS: Haematological and haemorheological measurements were made on blood collected from 26 spleen-intact patients with Gaucher disease, 16 splenectomised patients with Gaucher disease, 6 otherwise healthy asplenic non-Gaucher disease subjects and 15 healthy controls. RESULTS: No haemorheological differences could be demonstrated between spleen-intact patients with Gaucher disease and the control group. Compared to controls, both asplenic Gaucher disease and asplenic non-Gaucher disease study groups had a reduced MCHC (P = 0.003 and 0.005, respectively) and increased whole blood viscosity at 45% haematocrit (Hct), relative viscosity and red cell aggregation index - all measured at low shear (P < 0.05 for all). Additionally, asplenic patients with Gaucher disease alone showed an increased MCV (P = 0.006), an increased whole blood viscosity at 45% Hct measured at high shear (P = 0.019), and a reduced relative filtration rate (P = 0.0001), compared to controls. CONCLUSION: These observations demonstrate a direct and measurable haemorheological abnormality in Gaucher disease only revealed when there is no functioning spleen to control erythrocyte quality.

Erythrocyte hyper-aggregation in a patient undergoing orthotopic transplantation for primary sclerosing cholangitis complicated by biliary stricture.

We report on the hemorheological profile of a 16 year old school girl in whom liver transplant was performed due to primary sclerosing cholangitis complicated by biliary stricture. This patient turned out to be of particular hemorheological interest, displaying pre-transplant grossly increased hematocrit-standardized (45%) blood viscosity due to hyperaggregation and elevated plasma viscosity, which is a reflection of elevated immunoglobulins (IgG, IgA and IgM) and alpha-2-macroglobulin. Post-transplant values of rheological parameters were within the normal range for healthy controls.

Pregnancy at high altitude: a hyperviscosity state.

BACKGROUND: Pregnancy at high altitude has been associated with intrauterine growth restriction and preeclampsia. These conditions, at sea level, have been linked to increased hematocrit and blood viscosity. The aim of this study was to investigate the effect of high altitude on maternal hemorheology. METHODS: This was a cross-sectional study. We examined 94 pregnant women at 10-38 weeks of gestation resident at high altitude (4370 m above sea level) and 75 at sea level, and 24 and 17 nonpregnant women at each altitude, respectively. Blood and plasma viscosity, hematocrit, plasma fibrinogen, albumin and total protein concentrations were determined in blood samples obtained after an overnight period of fasting. RESULTS: Pregnancy at high altitude, compared to sea level, is characterized by higher hematocrit, blood viscosity (at high shear rate), plasma viscosity, total protein and fibrinogen concentrations (25%, 38%, 7%, 13.3% and 25%, respectively) and 6% lower albumin concentration. Nonpregnant women at high altitude, compared to sea level, had higher hematocrits, blood viscosity, plasma viscosity, total protein and fibrinogen concentrations (25%, 55%, 18%, 26% and 98%, respectively) and 13% lower albumin concentration. CONCLUSION: Pregnancy at high altitude compared to sea level is characterized by increased blood viscosity as a result of increased hematocrit and plasma viscosity.

Hyperviscosity as a complication in a variety of disorders.

For a considerable time, hyperviscosity syndrome has been widely recognized as a serious manifestation of polycythemia and plasma cell dyscrasia. In this article a number of conditions will be considered in which the association with hyperviscosity has been more recently recognized and is less widely known. These conditions are hyperleukocytosis, retinoic acid therapy, and connective tissue disease such as rheumatoid arthritis. The essential problems in the first two are the hugely elevated white cell count (WCC) and the mechanical properties of the leukocytes, in other words, their relatively poor deformability and their adhesiveness for the endothelium. In the last, the essential problem is hugely elevated plasma viscosity due to immunocomplexes. They lead to increased flow resistance, especially in the microvessels, abnormal flow, and significant clinical symptoms. The details of the causes of the hyperviscosity, the symptoms that result, and the forms of treatment are discussed.

Abnormal hemorheological properties in patients with compensated and decompensated hepatic cirrhosis.

In this study the hemorheological profiles of blood samples from cirrhotic patients (compensated and decompensated) were determined, along with 18 normal healthy volunteers for comparison. Both groups of patients were anaemic, and as a consequence had a lower native blood viscosity by comparison with the healthy control group. However, after adjusting the hematocrit to 45% the high shear rate (128 s(-1)) viscosity was within the normal range, while that at low shear rate (0.277 s(-1)) exhibited a significant increase in both groups of patients over that of the control group. This was partly due to the elevated plasma viscosities in the patients, but in the main is explained by exaggerated red blood cell aggregation. In spite of normal total plasma protein concentration in the patients, the concentration of rouleaugenic proteins was altered, and this particularly applied to the immunoglobulins (IgG, IgA and IgM). These results demonstrate that the hemorheology of the cirrhotics is disturbed from normal.

Effect of ionic strength of buffer on the measurement of erythrocyte electrophoretic mobility.

BACKGROUND: Measurement of the electrophoretic mobility (EM) of biological cells provides information on the electrical properties of the cell surface. Different research groups have used different electrophoretic techniques. It is well known that the osmolality of the buffer used during an experiment exerts a major impact on EM, particularly in biological cells. In previous experiments either high or low ionic strength electrophoresis buffers were used with an arbitrary preference. The aim of this study is to investigate which buffer is more useful for EM measurements, and hence to give greater insight into the results of such experiments. MATERIAL/METHODS: Blood was drawn from healthy volunteers. Two different buffers were prepared: low ionic and high ionic. Twenty molarity steps were prepared by mixing the buffers in different ratios. Measurements were made using a Zetasizer. RESULTS: Our data confirmed that the EM fell as ionic strength increased. However, the relationship was biphasic: the first ten points were linear with a steep negative slope and the second set also linear but with a much smaller slope. CONCLUSIONS: EM studies usually have one of two extreme aims: either to compare the inherent surface electrical properties of cells from different sources at the same ionic strength, or to study the influence of different ionic environments on the surface electrical properties of cells from the source. Our data suggest that in the first instance it is better to work at high ionic strength. In the second, low ionic strength is preferable.