Biorheology - Volume 51, issue 2-3

Authors: Koltai, Katalin | Papp, Judit | Kenyeres, Peter | Feher, Gergely | Tibold, Antal | Alexy, Tamas | Marton, Zsolt | Kesmarky, Gabor | Toth, Kalman

Article Type: Research Article

Abstract: BACKGROUND: Sex-specific response to antiplatelet medications have been reported in several previous studies. OBJECTIVE: We investigated a possible connection between gender differences in hemorheological parameters and in vitro platelet aggregation in vascular patients treated with widely used antiplatelet agents. METHODS: In vitro platelet aggregation was assessed in 2687 patients treated with 100 mg acetylsalicylic acid (ASA), 1047 patients treated with 75 mg clopidogrel and 311 patients on dual antiplatelet therapy (100 mg aspirin and 75 mg clopidogrel) according to the method of Born. In subgroups of patients fibrinogen concentration, whole blood and plasma viscosity, red blood cell aggregation …and hematocrit were simultaneously measured. The subjects were divided into groups according to their gender. RESULTS: ADP induced platelet aggregation was significantly higher in women in the case of ASA treatment (p<0.001). No gender differences could be observed in platelet function in patients treated with clopidogrel or on dual antiplatelet therapy. Hematocrit and whole blood viscosity were significantly higher in men in all groups (p<0.001), while no significant gender differences were observed in red blood cell aggregation indices in either group. Fibrinogen concentration was significantly higher in women than in men among patients treated with 100 mg ASA (p<0.05), but not in the other groups. CONCLUSIONS: Significantly higher fibrinogen concentration found in aspirin treated women than men may play a role in higher ADP induced platelet aggregation. Gender differences in response to monotherapy suggest that benefits from combination therapy may be greater in females. The clinical relevance of higher ADP induced platelet aggregation in women treated with ASA needs further investigation. Show more

Keywords: Aspirin, thienopyridines, viscosity, fibrinogen, erythrocyte aggregation, optical aggregometry

DOI: 10.3233/BIR-140661

Citation: Biorheology, vol. 51, no. 2-3, pp. 197-206, 2014

Authors: Jung, F. | Krüger, A. | Pindur, G. | Sternitzky, R. | Franke, R.P. | Gori, T.

Article Type: Research Article

Abstract: BACKGROUND: The role of the microcirculation in the pathophysiology and symptoms of peripheral arterial obliterative disease (PAOD) has been progressively emphasized during the past decades. Under resting conditions, already, the tissue oxygen partial pressure in the m. tibialis anterior (pO2im ) is reduced to about 50% compared to healthy subjects. METHODS: In the framework of this study the pO2im of patients with PAOD stage II according to Fontaine (n=16) in the m. tibialis anterior was measured under resting conditions and during walking on a treadmill in comparison to healthy subjects (n=10). RESULTS: Under resting conditions the pO2im …only marginally differed between PAOD patients and healthy subjects. But during exercise the pO2im dropped significantly more severely in PAOD patients and a return to baseline values could only be reached when the treadmill was stopped and the patients stood still. The pO2im minima correlated clearly with the clinical symptom of calf pain. CONCLUSION: The data revealed that the pO2im values were lower in PAOD patients and dropped significantly faster during walking compared to the pO2im values in healthy subjects. The pO2im decrease correlated with the calf pain occurring when the pO2im values approached or fell below 10 mmHg. Show more

Keywords: Tissue oxygen partial pressure, peripheral arterial occlusive disease, treadmill test

DOI: 10.3233/BIR-140651

Citation: Biorheology, vol. 51, no. 2-3, pp. 207-214, 2014

Authors: Cho, Minhee | Shin, Sehyun | Kwon, Hyuck Moon | Chung, Hyemoon | Lee, Byoung Kwon

Article Type: Research Article

Abstract: Myocardial ischemia may be present even when there is no significant stenosis of the epicardial coronary artery, or after coronary angioplasty for significant coronary artery disease. This phenomenon is related to disturbance of the coronary microcirculation or vasomotor tone. The aim of this study was to determine the influence of clinical and RBC hemorheological factors, such as RBC deformability and aggregation, on myocardial perfusion in patients with type 2 diabetes mellitus (DM) when compared to patients without DM, presenting with stable angina or acute coronary syndrome. Myocardial perfusion was graded using the myocardial blush grade (MBG) which describes the relative …“blush” or intensity of the radio-opacity of myocardial tissue observed after an epicardial coronary injection of contrast medium during coronary angiography. MBG was counted before any medical or mechanical intervention, and in the myocardial territory without anatomical flow limitation (<50% of luminal narrowing on coronary angiogram), in order to remove the direct influence of anatomical stenosis. Myocardial perfusion in this region was associated with diabetes, renal function, LV diastolic function, inflammatory biomarkers such as hs-CRP, fibrinogen and ESR, but not with the clinical presentation. Among the hemorheological parameters, reduced myocardial perfusion was linked to increased RBC aggregation, but not to variation in RBC deformability. In conclusion, myocardial perfusion was affected by diabetes, left ventricular diastolic function, and inflammatory activity indicated by clinical parameters, and by the hemorheological factor RBC aggregation. Show more

Keywords: Myocardial perfusion, diabetes, acute coronary syndrome, RBC aggregation

DOI: 10.3233/BIR-140659

Citation: Biorheology, vol. 51, no. 2-3, pp. 215-226, 2014

Authors: Muthard, Ryan W. | Diamond, Scott L.

Article Type: Research Article

Abstract: Millions of clotting tests each year require recalcification of blood treated with sodium citrate, a calcium chelator that prevents prothrombinase assembly. We validated a converging trifurcated microfluidic device to measure platelet and fibrin accumulation following on-chip recalcification of citrated whole blood. Recalcification was accomplished by sheathing the blood with Ca2+ buffer. Fluorescein rapidly diffused across the buffer-blood interface (achieving 62.5% of maximum centerline concentration within ~4 cm of flow), while albumin remained relatively unchanged in blood due to its lower diffusivity (<20% decrease). Since Ca2+ diffuses faster than fluorescein, full recalcification of whole blood was achieved within ~1 …cm of flow prior to encountering a collagen/tissue surface. Platelet and fibrin were reduced by 87.3% and 99.0%, respectively, when the sheath buffer was Ca2+ -free. A 30-min preincubation of citrated whole blood prior to on-chip recalcification increased platelet (159%) and fibrin (86.6%) deposition, compared to 5-min preincubation, likely due to factor XIIa generation in citrated blood. The P2Y1 inhibitor, MRS-2179, was delivered by diffusion into flowing blood and inhibited platelet deposition on collagen with a calculated IC50 of 0.155 μM. On-chip recalcification and drug dosing of citrated blood allows for assays of platelet function in a whole blood milieu under flow. Show more

Keywords: Thrombosis, citrate, fibrin, platelet

DOI: 10.3233/BIR-140658

Citation: Biorheology, vol. 51, no. 2-3, pp. 227-237, 2014