Increased Erythrocyte Aggregation Research Articles

Study of erythrocyte sedimentation in human blood through the photoacoustic signals analysis

IntroductionIn this study, we utilized the pulsed photoacoustic (PA) technique to analyze globular sedimentation in whole human blood, with a focus on distinguishing between healthy individuals and those with hemolytic anemia. MethodsBlood samples were collected from both healthy individuals (women and men) and those with hemolytic anemia, and temporal and spectral parameters of PA signals were employed for analysis. ResultsSignificant differences (p < 0.05) were observed in PA metrics between the two groups. The proposed spectral analysis allowed significant differentiation within a 25-minute measurement window. Anemic blood samples exhibited higher erythrocyte sedimentation rate (ESR) values, indicating increased erythrocyte aggregation. DiscussionThis study underscores the potential of PA signal analysis in ESR assessment as an efficient method for distinguishing between healthy and anemic blood, surpassing traditional approaches. It represents a promising contribution to the development of precise and sensitive techniques for analyzing human blood samples in clinical settings.

Evaluation of erythrocyte membrane oxidation due to their exposure to shear flow generated by extracorporeal blood pump.

Several similarities have been found between shear stress-induced erythrocyte damage and physiological aging of erythrocytes in terms of elevated mechanical fragility, increased erythrocyte aggregation, and decreased membrane surface charge. Accordingly, we hypothesized that blood pump circulation, which generates shear stress, would accelerate erythrocyte aging, manifesting as oxidation. Therefore, the purpose of this study was to investigate the effect of blood pump circulation on erythrocyte oxidation. Fresh porcine blood was acquired from a slaughterhouse and anticoagulated with sodium citrate. About 500 mL of anticoagulated whole blood was circulated for 180 min in an in vitro test circuit comprising a BP-80 blood pump with a pump speed and a pump pressure head of 100-120 mmHg. A blood sample was taken at the start of the circulation and 180 min afterward. The hemolysis level and oxidation amount of the erythrocyte membrane were analyzed and compared between samples. Hemolysis increased with the prolongation of shear exposure inside the pump circuit. After 180 min of blood pumping in circuit, the oxidation level of the erythrocyte membrane showed an increase of 0.1 nmol/mg protein. Moreover, the membrane oxidation levels of sheared erythrocytes were greater than those of control erythrocytes. These results suggest that blood pump circulation accelerates erythrocyte aging and give us a greater understanding of the effects of blood pump perfusion.

The Impact of COVID-19 on Cellular Factors Influencing Red Blood Cell Aggregation Examined in Dextran: Possible Causes and Consequences.

Several studies have indicated that COVID-19 can lead to alterations in blood rheology, including an increase in red blood cell aggregation. The precise mechanisms behind this phenomenon are not yet fully comprehended. The latest findings suggest that erythrocyte aggregation significantly influences microcirculation, causes the formation of blood clots in blood vessels, and even damages the endothelial glycocalyx, leading to endothelial dysfunction. The focus of this research lies in investigating the cellular factors influencing these changes in aggregation and discussing potential causes and implications in the context of COVID-19 pathophysiology. For this purpose, the aggregation of erythrocytes in a group of 52 patients with COVID-19 pneumonia was examined in a 70 kDa Dextran solution, which eliminates the influence of plasma factors. Using image analysis, the velocities and sizes of the formed aggregates were investigated, determining their porosity. This study showed that the process of erythrocyte aggregation in COVID-19 patients, independent of plasma factors, leads to the formation of more compact, denser, three-dimensional aggregates. These aggregates may be less likely to disperse under circulatory shear stress, increasing the risk of thrombotic events. This study also suggests that cellular aggregation factors can be responsible for the thrombotic disorders observed long after infection, even when plasma factors have normalized. The results and subsequent broad discussion presented in this study can contribute to a better understanding of the potential complications associated with increased erythrocyte aggregation.

Effects of biomechanical properties of blood on surface tension-driven flows in superhydrophilic channels

Surface tension-driven microfluidic flows offer low-cost solutions for blood diagnostics due to the pump-less flow handling. Knowledge of the influence of the biomechanical properties of blood on such flows is key to design such devices; however, a systematic examination of that influence is lacking in the literature. We report on the effects of specific hemorheological factors for flows in a superhydrophilic microchannel. Whole human blood and erythrocyte suspensions in phosphate buffer and dextran solutions were tested. Heat-treated counterparts of the aforementioned samples were produced to alter the deformability of the cells. The flow of the samples was imaged and characterized using micro-particle image velocimetry and tracking techniques to probe the effects of hematocrit, and erythrocyte aggregation and deformability. Meniscus velocities, velocity profiles in the channel, and local and bulk shear rates were derived. The mean velocity of blood was affected by the increasing sample viscosity and the reduced erythrocyte deformability as expected. The increased erythrocyte aggregation appeared to affect more the shape of the velocity profiles in the normal, compared to the heat-treated samples. Very high shear rates are observed in the early stages of the flow, suggesting high erythrocyte disaggregation, persisting sufficiently strong until the flow reaches the end of the channel.

FEATURES OF THE DIAGNOSIS OF JOINT INJURIES OF THE FACIAL SKELETAL BONES, TAKING INTO ACCOUNT THE HEMORRHAGIC PROPERTIES OF THE BLOOD

In this study, the diagnostic aspects of facial bone joint injuries were studied in 120 patients, taking into account the hemorrhagic features of the blood. The results of our study showed that in patients with a joint injury of the middle part of the facial skeleton, there are changes in the indicators of functional activity of the endothelium, which peak in 3-5 days. Increased blood viscosity syndrome, increased erythrocyte aggregation, and decreased erythrocyte deformation were also identified. In the course of treatment of patients there is no complete recovery of the indicators characterizing the rheological properties of the blood.

Динамика морфофункциональных показателей эритроцитов при действии сульфгидрильного ингибитора ангеотензин-превращающего фермента фентиаприла в экспериментальном моделировании артериальной гипертензии

Here, we studied the effect of fentiapril on the morpho-functional parameters of erythrocytes in the experimental model of arterial hypertension (AH). The drug was administered once, intraperitoneally, at the dose of 20 mg/kg. The dynamics of the changes in the electrophoretic mobility of erythrocytes (EME), their aggregation ability, ATP and 2,3 DFG concentration in the erythrocytes, the lipid peroxidation activity (by MDA content), the number of erythrocytes and gross hemoglobin amount, the volume of erythrocytes, the single-erythrocyte hemoglobin content, and the hematocrit, were assessed 30 and 60 min, as well as 24 hours after the drug administration. An increased erythrocyte aggregation, decreased EME, increased MDA and 2,3 DFG amid concentration, decreased ATP concentration, increased erythrocyte and hemoglobin amount, as well as increased hematocrit were demonstrated in the AH model. Application of fentiapril led to a decrease in the erythrocyte aggregation, as well as their number, decrease in the hemoglobin content and hematocrit, an increase in the MDA and 2,3DFG concentration accompanied byt the decrease in the ATP concentration, compared to the animals with hypertension during 1 day of registration, and an increase in the electronegativity of erythrocytes during the 30–60 min of the experiment, with maximal decrease in blood pressure observed at 60 min of registration. The decreased blood pressure under the fentiapril action was accompanied by the restoration of the studied erythrocyte characteristics to the values ​​similar to those observed in intact animals, whereas the increased blood pressure led to a decrease in the erythrocyte membrane electronegativity and an increase in lipid peroxidation.

Increased erythrocyte aggregation following an acute bout of eccentric isokinetic exercise does not exceed two days.

Isokinetic exercise is used to reduce strength imbalance and to enhance performance. The aim of this study was to investigate the acute effects of a single bout of eccentric isokinetic exercise on hemorheology (erythrocyte deformability and aggregation), total oxidant/antioxidant status (TOS/TAS) and oxidative stress index (OSI) in active individuals. The study comprises 11 active, healthy, male subjects (mean age of 19.45 ± 0.31 years, BMI 22.05 ± 0.51 kg/m2). They performed single, unilateral eccentric contractions of knee flexors and extensors with dominant leg on a dynamometer. Isokinetic hamstring, quadriceps strength were recorded at eccentric (30, 120° s-1) angular velocities. Eight active age-matched healthy male subjects were included as a control group, who did not receive exercise. Blood samples were obtained before, immediately after and two days after the exercise session. Hemorheological parameters were measured by an ektacytometer. TOS/TAS were determined using a commercial kit. A session of eccentric isokinetic exercise did not affect erythrocyte deformability and oxidative stress indices, whereas red blood cell (RBC) aggregation was increased initially and returned to pre-exercise levels after two days following exercise. Our results suggest that, increased RBC aggregation following an acute bout of isokinetic exercise may result in increased plasma skimming that augments tissue perfusion and clearance of metabolites within a period of two days following exercise.

Effects of Eccentric and Concentric Cycling Exercise Regimens on Hemodynamic and Hemorheologic Properties in Sedentary Males

Erythrocyte rheological properties significantly contribute to the dynamic regulation of vascular resistance to flow shear force, whereas impaired rheological functions of erythrocytes lead to circulatory disorders and exercise intolerance. This study investigated whether eccentric (ECE) and concentric (CCE) cycling exercise regimens influence hemorheological/hemodynamic responses to hypoxic stress in sedentary males. Twenty‐two healthy sedentary men were randomized to either ECE (n=11) or CCE (n=11) group. These subjects progressively performed ECE or CCE at 45% to 70% VO2max on a bicycle ergometer for 40 min/day, 5 days/week for 6 weeks. Erythrocyte rheological and central/peripheral hemodynamic characteristics at rest and after hypoxia exercise test (HE, 100W under 12% O2 for 40 min) were determined by laser diffraction ektacytometer and bioreactance‐based device/near infrared spectrometer, respectively. The result demonstrated that HE reduced erythrocyte deformability and increased erythrocyte aggregability under shear flow whereas CCE rather than ECE attenuated the extents of erythrocyte rheological impairment caused by HE. Although cardiac hemodynamic responses to exercise in the ECE group were smaller than those in the CCE group, the percentages of blood distributed to frontal cerebral lobe and vastus lateralis muscle in ECE group were larger than those in CCE group. Hence, we conclude that CCE effectively increases the resistance to hemorheological impairment evoked by HE, whereas ECE prominently enhances cerebral/muscular hemodynamic adaptions to exercise in sedentary males.

Hemorheological factors can be informative in comparing treatment possibilities ofabdominal compartment syndrome.

Abdominal compartment syndrome (ACS) is alife-threatening condition, of which pathomechanism hasn't been completely clarified, yet. Furthermore, surgical therapy still needs optimization. We aimed to investigate microcirculatory and micro-rheological alterations in ACS, using various temporary abdominal closure methods, including three settings of vacuum-assisted closure technique (negative pressure wound therapy, NPWT). On anesthetized pigs, by intraabdominally placed and filled-up silicone bags, intraabdominal pressure at 30 mmHg was maintained for 3hours, and afterwards, decompressive laparotomy happened. In different experimental groups Bogota-bag or Vivano abdominal sets were applied (-50, -100, -150 mmHg) for 2hours. Pressure monitoring was done by implanted sensors, hemorheological parameters were determined, and laser Doppler flowmetry tests were performed on the surface of intraabdominal organs. Treatment with Bogota-bag and -150 mmHg vacuum increased erythrocyte aggregation, while deformability declined. Blood viscosity increased after treatment with -150 mmHg vacuum. The microcirculatory parameters of the NPWT groups were better in small intestine. ACS resulted in impairment of macro- and micro-rheological parameters and abdominal organs' microcirculation. All of the used techniques improved the results, however, applying Bogota-bag or -150 mmHg vacuum set showed worse microcirculatory and micro-rheological data than the settings at -100 or -50 mmHg.

Increased erythrocyte aggregation in infectious diseases: Influence of “acute phase proteins”

Increased erythrocyte aggregation in infectious diseases: Influence of “acute phase proteins”

Increased erythrocyte aggregation in patients with primary open angle glaucoma

BackgroundThe rationale of this study is to determine alterations in blood rheology (erythrocyte aggregation and deformability) and relationship between structural measurements obtained from optical coherence tomography (OCT) in different stages of primary open angle glaucoma (POAG).MethodsThis prospective controlled study comprised 23 POAG patients (glaucoma group) and 23 age‐ and sex‐matched healthy subjects (control group). Elongation index (EI), which is the indicator of erythrocyte deformability and erythrocyte aggregation was measured using an ektacytometer. Optic nerve head (ONH) morphology and peripapillary retinal nerve fibre layer (RNFL) thickness were evaluated using a spectral domain (SD) OCT.ResultsThere were no significant differences between the groups regarding the elongation index values (p > 0.05). On the other hand, erythrocyte aggregation amplitude (AMP) and mean corpuscular haemoglobin concentration (MCHC) were significantly higher in the glaucoma group than in the control group (p = 0.015, p = 0.003 respectively). A significant correlation was also found between the elongation index and retinal nerve fibre layer (average and superior) thickness (p < 0.05) in patients with late glaucoma.ConclusionsIn patients with POAG, erythrocyte aggregation appears to be higher. It can be speculated that higher erythrocyte aggregation and deformability may be involved in the pathogenesis of glaucoma by affecting microperfusion of the optic nerve head and retina. Modification of rheological parameters in patients with glaucoma may be considered as an adjuvant future therapy in glaucoma management, whereas further studies in larger groups are needed.

PO-59 - Hemorheologic disturbances as thrombosis risk factor in patients with some myeloproliferative neoplasms

In today's antithrombotic prevention we forget that hemorheologic abnormalities are part of Virchow's triad. Isn't this one of reasons that venous thromboembolism (VTE) including catheter-related thrombosis (CRT) retain high frequency despite of modern antithrombotic therapy? The aim was to investigate rheological behavior of blood in patients with some myeloproliferative neoplasms. The study included 16 adults with Polycythemia Vera (PV), 42 young with acute lymphoblastic leukemia (ALL), and 67 healthy donors as control group. Of patients 38% had thrombosis. We measured plasma viscosity, and whole blood viscosity (WBV) by shear rate from 300 to 5 s-1. Then indices were calculated for erythrocyte aggregation, and deformability, and non-Newtonian behavior of blood. Hematocrit, erythrocytes count, erythrocyte indices, leukocyte count, fibrinogen and B-type natriuretic peptide (BNP) were analyzed simultaneously. Increased WBV revealed totally in PV-patients but not by all shear rates in ALL-patients. Unlike donor, in patients WBV values had no equivalence under sequential one sample measurements with a decrease and then an increase of shear rates. We speculated this difference becomes diagnostic meaning like one and by its size. WBV dependent on leukocytes count, on MCH and mainly on MCV. Forty percent of patients had elevated BNP assuming subclinical cardiac dysfunction. The latter explains discoordinated changes in shear stress values required for fully reversible erythrocyte aggregation. As a result, residual units like "erythrocyte-erythrocyte" and/or "erythrocyte-leukocyte" interferes blood stream and violates mechanically blood flow in small vessels. Moreover in PV-patients but not in ALL-patients we found loss of non-Newtonian behavior of blood later than in control group. Both myeloproliferative neoplasms lead to increased erythrocyte aggregation but not impair deformability of red blood cells. In total these facts explains chronic hypoxia in these patients. Patients with some myeloproliferative neoplasms has abnormal blood flow properties. Revealed hemorheologic disturbances could be as a trigger to start of VTE or to growth of blood clot in the area of permanent venous catheter. These non-hemocoagulation conditions leaded for thrombus formation makes hemorheologic therapy looking attractive for antithrombotic management. The choice of targeted methods requires to continue this study.

Association of altered hemorheology with oxidative stress and inflammation in metabolic syndrome

ObjectiveWe have shown increased whole blood viscosity (WBV), decreased erythrocyte deformability, and increased erythrocyte aggregation in metabolic syndrome (MetS) in our previous study. The objective of the study was to find out if the altered hemorheology shown in MetS in our previous study is associated with chronic inflammation and oxidative stress in the same subjects.MethodsOne hundred recruited participants were classified into three groups based on the number of the MetS components present following National Cholesterol Education Program, Adult Treatment Panel III definitions. WBV, erythrocyte aggregation, erythrocyte deformability, oxidative stress markers (erythrocyte reduced glutathione (GSH), superoxide dismutase (SOD), and urinary isoprostanes), inflammatory markers high-sensitivity C-reactive protein (hsCRP), and thrombotic marker D-dimer were measured. Data were analyzed by IBM SPSS 20 software.ResultsWe found a significant association of altered hemorheology with chronic inflammation and oxidative stress in MetS. There was a linear increase in the level of hsCRP and a linear decrease in the level of SOD and GSH across the quartiles of erythrocyte aggregation. Similarly, the thrombotic marker D-dimer showed a linear increase and oxidative stress marker GSH showed a linear decrease trend across the quartiles of WBV.DiscussionAlterations of hemorheology in MetS are probably due to the effect of chronic inflammation and oxidative stress. The negative effects of chronic inflammation and oxidative stress on the cardiovascular system could be due to the resulting altered hemorheology.

Hyperviscosity in plasma cell dyscrasias

Plasma cell dyscrasias are characterized by a malignant clonal proliferation of plasma cells. Due to the excessive production of abnormal clonal gammaglobulins, or paraproteins, there are major hemorheologic changes in the circulation. As a result, clinical manifestations of the hyperviscosity syndrome become a major cause of morbidity and mortality. Pathogenic factors for the hyperviscosity are due both to increased plasma viscosity and to increased erythrocyte aggregation, leading to increased whole blood viscosity. These changes are dependent on the plasma concentration as well as the molecular size of the paraprotein with the threshold for onset of hyperviscosity for IgG >15 g/dl, for polymerized IgG3 >4-5 g/dl, for IgA >10-11 g/dl; for polymerized IgA >6-7 g/dl and for IgM >3 g/dl. Correspondingly, the incidence of symptomatic hyperviscosity in Waldenstrom's macroglobulinemia is 10-30%, while that in IgG myeloma is 2-6%. Clinically, the syndrome has neurologic features of headache and dizziness, visual changes, renal failure, and cardiac failure from increased plasma volume. Thrombotic complications are frequent. Paradoxically, there can be bleeding complications due to impairment of platelet function. Removal of the paraprotein by plasma exchange (plasmapheresis) can effectively reduce the hyperviscosity. Long-term control of paraprotein production can be achieved by chemotherapy. The early recognition of the symptoms of hyperviscosity, confirmed by laboratory findings of increased paraproteins and of increased blood viscosity, is essential for the proper management of this group of disorders.

Relationships between insulin sensitivity measured with the oral minimal model and blood rheology

In studies using the intravenous glucose tolerance test with minimal model analysis we reported that low insulin sensitivity (SI) is associated with increased erythrocyte aggregability and plasma viscosity, that appeared to be markers of insulin resistance. Recently, development of modelling has made available a new approach of insulin sensitivity from oral glucose tolerance test data (oral minimal model). We aimed at determining in 111 subjects (51 men, 62 women, age 11-77 yr), insulin sensitivity with this approach together with blood viscosity parameters. With this approach the Myrenne indexes of red cell aggregation were negatively correlated to SI (M; r = -0.456; p = 0.0007; M1; r = -0.397; p = 0.004) while plasma viscosity was not. Correlations with fasting insulin levels (Ib) were weaker (M; r = 0.2711; p = 0.05; M1; r = 0.373; p = 0.007). Accordingly, a stepwise regression analysis selects M as the best correlate of SI and M1 as the best correlate of Ib. With this approach plasma viscosity does not exhibit any clear relationship with SI. This study supports the concept that RBC hyperaggregability is the prominent hemorheologic symptom of insulin resistance.

Minimal model-derived insulin sensitivity, insulin secretion and glucose tolerance: relationships with blood rheology

Insulin resistance is associated with a mild hyperviscosity syndrome, which is more closely related to insulin resistance than to the clinical scoring of the metabolic syndrome. In studies using the intravenous glucose tolerance test with minimal model analysis we reported that low insulin sensitivity (SI) is associated with increased erythrocyte aggregability (EA). Actually, this issue is confusing because insulin resistance is often associated with compensatory hyperinsulinemia (insulin being a hormone with reported hemorheologic effects) and that a decline in insulin secretion has marked metabolic effects that modify blood rheology. From the intravenous glucose tolerance test (IVGTT) the minimal model allows the calculation of SI, insulin response, and an overall glucose tolerance parameter termed "disposition index" (DI) that measures whether insulin response is adequate or not for the level of insulin sensitivity. In this study we assessed SI, insulin response, and DI during an IVGTT in 335 subjects of both genders (age 8-77 yr; BMI 14-67 kg/m2). SI was only correlated (negatively) with EA (Myrenne M r = -0.285; p = 0.0001; M1 r = -0.240 p = 0.003). Fasting insulin was also correlated (positively) with EA (Myrenne M r = 0.233, 0.00880; M1 r = 0.320 p = 0.0003; SEFAM TA r = -0.342 p = 0.04; SEFAM S60 r = 0.419 p = 0.01) and SEFAM RBC disaggregation thresholds (γS = r = 0.372 p = 0.025; γD = r = 0.504 p = 0.002). Fasting DI (SI × fasting insulin) is negatively correlated to M (r = -0.274; p = 0.002) and M1 (r = -0.225; p = 0.01) but also positively to whole blood viscosity (r = 0.168; p = 0.01) and hematocrit (r = 0.142; p = 0.05). Stimulatory DI (SI × insulin peak) fails to be correlated with any parameter of EA but is negatively correlated to whole blood viscosity (r = -0.150; p = 0.02) and plasma viscosity (r = -0.163; p = 0.01). This study confirms that red cell aggregability is associated with insulin resistance and hyperinsulinemia, but plasma viscosity seems to be more related to overall glucose tolerance than to either SI or insulinemia.

Rheological alterations and thrombotic events in patients with systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is characterised by increased venous and arterial thrombotic risk. Nevertheless, how hemorheological alterations contribute to thrombotic risk remains a question of debate. We aimed to determine the rheological profile in 105 patients with SLE (24 with a thrombotic event) and 105 healthy controls. We determined blood viscosity and erythrocyte aggregation along with plasma lipids and fibrinogen. Although SLE patients showed lower blood viscosity at 230 s(-1) at a native hematocrit when compared with controls (p < 0.001), differences disappeared after adjusting the hematocrit to 45% (p = 0.095). When comparing SLE patients with and without thrombotic events, no differences in any rheological parameter were found (p > 0.05), except in fibrinogen which was higher in patients with thrombosis (p = 0.013). No differences in the rheological parameters were observed when venous and arterial thrombotic events were compared, although a tendency for higher fibrinogen was observed in patients with venous thrombosis (p = 0.053). Only hematocrit, fibrinogen and triglycerides were independent predictors of native blood viscosity in the multivariate regression analysis, even after adjusting for continuous variables and for tobacco and hypertension: beta coefficient: 0.727 p < 0.001; beta coefficient: 0.152 p = 0.003 and beta coefficient: 0.133 p = 0.015, respectively. The logistic regression analysis revealed that neither increased native blood viscosity (BVn > 4.33) nor increased erythrocyte aggregation (EA1 > 7.85) increased thrombotic risk: OR 0.636, CI 0.313-3.12, p = 0.578 and OR 2.01, CI 0.77-5.20, p = 0.152, respectively. However, hyperfibrinogenemia (Fbg > 342 mg/dL) increased thrombotic risk by around three times: OR 3.44 CI 1.32-8.96, p = 0.011. Our results suggest that the role of blood viscosity and erythrocyte aggregation in thrombotic risk in SLE patients fails to demonstrate any association.

Analysis of Complex Viscosity in a Group of Patients with Circulation Disorders

Rheology of viscoelastic uids is a complex phenomenon. Full blood is an example of a body uid of non-Newtonian character with pronounced viscoelastic properties. Blood ow in the circulatory system depends not only on the physical and physico-chemical properties of blood but also on the structure and properties of the vascular system. Blood viscosity is one of the most important factor determining the blood ow. Its value depends on the shear rate, hematocrit, erythrocyte aggregability and deformability, and on the plasma viscosity and composition. In the course of the investigation we utilized oscillatory methods, called also dynamic mechanical analysis. The technique principle is based on the measurement of the amplitude and phase of oscillations of the sample subject to a harmonic force with certain amplitude and frequency. The results of dynamic mechanical analysis were used to determine the viscoelastic properties of blood samples. We performed also the standard ow curve measurements of the blood plasma samples, that is shear stress as a function of shear rate in the rotary mode. All measurements were performed by means of a Contraves LS-40 rheometer on blood samples taken from two groups of patients. One group contained patients after heart attack, while the second one after cerebral infarction. In none of the groups the patients were in an acute state. Information obtained from oscillatory measurements indicate increased erythrocyte aggregability in both groups of patients.

Aggregation and deformability of erythrocytes in primary open-angle glaucoma (POAG); the assessment of arterial hypertension

Primary open-angle glaucoma (POAG) is one of the most common types of glaucoma. Glaucoma is a progressive neuropathy of the optic nerve with characteristic visual area disorders. The aim of this study was to assess the correlations between rheological parameters of blood and other parameters such as: intraocular pressure, visual acuity, angular breadth of the aqueous fluid eluvium, visual area and arterial hypertension. The examined group was comprised of 54 patients with POAG. Out of this group two subgroups was separated: I subgroup of 24 patients without hypertensive and II subgroup of 30 patients with chronic hypertensive disease. The control group was comprised of 40 healthy subjects. Erythrocyte aggregation and deformability analysis were determined using LORCA. From the results we concluded that rheological disorders such as enhanced erythrocyte aggregation or significantly decreased erythrocyte deformability occur in patients with POAG. Additionally, it revealed a significant relation between the duration of hypertension and an increased erythrocyte aggregation index (r = +0.27 p < 0.005) along with decreased deformability (r = -0.37 p < 0.001), where the decrease in deformability correlated with the severity of hypertonic retinal angiopathy (r = -0.30 p < 0.05). All these disorders may result in decreased blood flow to the optic nerve, which contributes towards the development of neuropathy.

Response to the letter: How to manage coronary slow flow following PCI?

We read with pleasure the letter by Korkmaz et al. [1] regarding therapeutic options for slow flow in the coronary circulation. Their letter was in response to our recently published study showing that ACS is related to increased erythrocyte aggregation regardless of fibrinogen levels. Our results hint to the fact that interfering with fibrinogen activity might improve microcirculatory flow [2], and therefore suggested the use of fibrinolytic therapy. We agree with the author that pentoxifylline could offer a beneficial effect on blood viscosity and therefore, might be another therapeutic option. Nevertheless, it is important to note that thrombolytics work much faster compared to pentoxifylline and therefore, might be more suited in the acute cases while, pentoxifylline with a better safety profile might be more suited for chronic cases. However, as was found in our study, therewas little relation between fibrinogen levels and erythrocyte aggregates in non ACS patients and therefore, we will need more clinical studies in order to better define the role of pentoxifylline in treatment of patients with slow coronary flow.