Clinical Hemorheology and Microcirculation - Volume 59, issue 3

Authors: Wallmichrath, J. | Birk, C. | Baumeister, R.G.H. | Engelhardt, T.O. | Giunta, R.E. | Frick, A.

Article Type: Research Article

Abstract: BACKGROUND: The purpose of this study was to determine whether the focused delivery of heparin or recombinant tissue plasminogen activator (rtPA) by rinsing accords protective effects which increases the survival of free groin flaps following fatal secondary venous stasis. METHODS: Free microvascular groin flaps (n = 40) were transplanted to the necks of adult Sprague-Dawley rats 20 hours before the experiment. The study groups (each n = 10 animals) were: No adjunctive treatment (Group I), Ringer's solution (Group II), heparin solution (100 IU/kg, group III) and rtPA (2 mg/kg, group IV), respectively. The flap vein was then clamped for 35 …minutes. Intravital video microscopy was applied and flap viability was assessed 14 days later. RESULTS: Mean flap necrosis was 90% in group I and II, whereas the rate of flap survival was 80% in group III and 60% in group IV, respectively. CONCLUSIONS: Even though clinical and microvascular flap perfusion parameters in both the rtPA-group and heparin group were initially similar, it has been demonstrated here in our investigations that the flaps treated with heparin showed a higher viability rate. Therefore, we can conclude that the focused delivery of heparin and rtPA resulted in a significantly improved flap salvage. Show more

Keywords: Heparin, rtPA, recombinant tissue plasminogen activator, free flap, rat model, groin flap, microsurgery, intravital microscopy, IVM, ischemia, reperfusion, I/R

DOI: 10.3233/CH-131756

Citation: Clinical Hemorheology and Microcirculation, vol. 59, no. 3, pp. 185-195, 2015

Authors: Yeom, Eunseop | Lee, Sang Joon

Article Type: Research Article

Abstract: Pulsatile blood flows are easily found in the vessels of living organisms. Under pulsatile flow conditions, red blood cells (RBCs) are aggregated and dispersed repetitively. The phenomenon of RBC aggregation is an influential factor in hemorheological and hemodynamic properties. This study aims to investigate the relationship between velocity profile and RBC aggregation in pulsatile blood flows. A rat extracorporeal bypass model was adopted to generate a real pulsatile flow without changing the rheological properties. To check the stability of the experimental model, variations of the hemodynamic parameters were measured consecutively for 2 h. Ultrasound speckle images of the blood flow …in the extracorporeal bypass loop were acquired using a 35-MHz ultrasound scanner. The velocity fields were measured by the speckle image velocimetry (SIV) method, in which the cross-correlation algorithm is applied to the speckle images. In addition, the RBC aggregation was estimated by analyzing the echogenicity distribution of the speckle images. The shape of the velocity profile was cyclically varied according to the cardiac cycle. This variation may be closely related to the variation of the echogenicity distribution in pulsatile flows. The simultaneous measurement of velocity and RBC aggregation would be useful for understanding the effects of the hemorheological features on the hemodynamic characteristics of pulsatile blood flows. Show more

Keywords: Echogenicity, pulsatile blood flow, rat extracorporeal bypass loop, red blood cell (RBC), RBC aggregation, speckle image velocimetry, velocity profile

DOI: 10.3233/CH-131759

Citation: Clinical Hemorheology and Microcirculation, vol. 59, no. 3, pp. 197-209, 2015

Authors: Heo, Yujin | Jung, Hyunwoo | Shin, Sehyun

Article Type: Research Article

Abstract: Red blood cell (RBC) deformability is greatly affected by the osmolality, and maximum deformability, which is determined as maximal elongation index (EImax ), is usually observed in isotonic conditions at high shear stresses (>20 Pa). Therefore, we examined osmotic RBC deformability over a range of shear stresses (0.5–20 Pa). We found that the RBC deformability at low shear stresses (1–3 Pa) was maximum in hypotonic conditions (225–250 mOsm/kg H2 O), which is slightly lower than the normal range of osmolality in plasma (290–310 mOsm/kg H2 O). The phenomenon that Omax (the osmolality at EImax ) is dependent on applied …shear stress could play an important role in microcirculation in which osmolality varies widely. Show more

Keywords: RBC, deformability, osmolality, shear stress, in vivo

DOI: 10.3233/CH-131761

Citation: Clinical Hemorheology and Microcirculation, vol. 59, no. 3, pp. 211-218, 2015

Authors: Lutter, Christoph | Nothhaft, Matthias | Rzany, Alexander | Garlichs, Christoph D. | Cicha, Iwona

Article Type: Research Article

Abstract: BACKGROUND: In coronary artery disease, highly stenosed arteries are frequently treated by stent implantation, which thereafter necessitates a dual-antiplatelet therapy (DAPT) in order to prevent stent-thrombosis. We hypothesized that specific patterns of microstructures on stents can accelerate endothelialisation thereby reducing their thrombogenicity and the DAPT duration. METHODS: Differently designed, 2–5 μm high elevations or hollows were lithographically etched on silicon plates, subsequently coated with silicon carbide. Smooth silicon plates and bare metal substrates were used as controls. To assess attachment and growth of human umbilical vein endothelial cells under static or flow conditions, actin cytoskeleton was visualised with green phalloidin. …Endothelial migration was assessed in a modified barrier assay. To investigate surface thrombogenicity, platelets were incubated on the structured surfaces in static and flow conditions, and visualised with fluorescein-conjugated P-selectin antibody. Images were taken with incident-light fluorescent microscope for non-transparent objects. RESULTS: Compared to smooth surface, flat cubic elevations (5 μm edge length) improved endothelial cell attachment and growth under static and dynamic conditions, whereas smaller, spiky structures (2 μm edge length) had a negative influence on endothelialisation. Endothelial cell migration was fastest on flat cubic elevations, hollows, and smooth surfaces, whereas spiky structures and bare metal had a negative effect on endothelial migration. Thrombogenicity assays under static and flow conditions showed that platelet adhesion was reduced on the flat elevations and the smooth surface, as compared to the spiky structures, the hollow design and the bare metal substrates. CONCLUSION: Surface microstructures strongly influence endothelialisation of substrates. Designing stents with surface topography which accelerates endothelialisation and reduces thrombogenicity may be of clinical benefit by improving the safety profile of coronary interventions. Show more

Keywords: Atherosclerosis, stent endothelialisation, stent thrombogenicity, surface topography

DOI: 10.3233/CH-141839

Citation: Clinical Hemorheology and Microcirculation, vol. 59, no. 3, pp. 219-233, 2015

Authors: Soliman, Amr A. | Wojcinski, Sebastian | Degenhardt, Friedrich

Article Type: Research Article

Abstract: PURPOSE: Acoustic radiation force impulse (ARFI) imaging technology provides measurable values of the elasticity/stiffness of the tissues examined. This work is a pilot study to determine the shear wave velocity values of normal endometrium and myometrium in healthy asymptomatic women. METHODS: In a prospective observational study that recruited asymptomatic women, we used the ARFI (Virtual Touch tissue quantification™; Siemens Medical Solutions) to examine six different points in the uterus of each woman; two points in the endometrium and four points in the myometrium. Two readings were obtained at each of the examined points to test the intra-observer reproducibility. RESULTS: A …total of 32 women were recruited. The age range was 19–68 years with a median age of 42 years. The menopausal status did not have any significant influence on the shear wave velocity measurements. The mean readings in the endometrium were 1.96, 2.03, 2.04 and 2.08 m/s while in the myometrium they were 2.78, 2.85, 2.87, 2.89, 2.91, 2.99, 3.2 and 3.23 m/s, respectively. CONCLUSIONS: The ARFI procedure is a novel, reproducible ultrasonographic modality that can provide information about tissue stiffness. Transvaginal transducers fitted with this technology are sought as well as larger studies validating our findings. Show more

Keywords: ARFI imaging, ultrasonographic examination of the uterus, myometrium, endometrium

DOI: 10.3233/CH-141842

Citation: Clinical Hemorheology and Microcirculation, vol. 59, no. 3, pp. 235-243, 2015

Authors: Hammes, Mary S. | Watson, Sydeaka | Coe, Frederic L. | Ahmed, Faris | Beltran, Emily | Dhar, Promila

Article Type: Research Article

Abstract: BACKGROUND: Renal failure is a disease with accelerated atherosclerosis beginning with endothelial cell dysfunction. Factors affecting endothelial cell dysfunction include whole blood viscosity (WBV) and asymmetric dimethylarginine (ADMA). The relationship in controls and renal failure was determined. METHODS: 51 subjects, 20 controls, 11 renal transplant recipients, 10 chronic kidney disease and 10 end-stage renal disease patients had blood samples drawn for WBV, Hematocrit, and ADMA. WBV was measured at various shear rates from 10 s−1 to 780 s−1 at 37°C. Hematocrit using CritSpin, and ADMA was assayed using an ELISA method. The significance between groups was compared by …boxplots and analysis of variance. Linear relationships were shown by regression lines and correlation coefficients. RESULTS: ADMA was elevated in all groups with renal failure when compared to controls (p < 0.05). Control subjects showed a positive correlation between ADMA and WBV, while those who received a renal transplant had a negative correlation (p < 0.05). The difference in ADMA comparing pre-dialysis to post-dialysis conditions was positive (p < 0.05). CONCLUSIONS: The positive relationship between WBV and ADMA in controls is a novel finding and allows for comparison with other groups. This relationship is dramatically altered in renal failure. Show more

Keywords: Asymmetric dimethylarginine, endothelial cell, nitric oxide, renal failure, viscosity

DOI: 10.3233/CH-141843

Citation: Clinical Hemorheology and Microcirculation, vol. 59, no. 3, pp. 245-255, 2015

Authors: Zhou, Juan | Zimmermann, Katrin | Krieg, Thomas | Soltow, Marieke | Pavlovic, Dragan | Cerny, Vladimir | Lehmann, Christian

Article Type: Research Article

Abstract: Gut ischemia and reperfusion (IR), e.g. in small bowel transplantation or during resuscitation, may result in severe impairment of the intestinal microcirculation. Potential sequelae are mucosal damage, loss of intestinal barrier function, bacterial translocation, systemic inflammation, multiple organ failure and death. We hypothesized a protective role for extracellular adenosine signalling in intestinal IR injury. Using intravital microscopy we investigated the effects of the adenosine receptor (AR) agonist NECA (5′-N-ethyl carboxamide adenosine) on leukocyte-endothelial interactions and capillary perfusion in the intestinal microcirculation following intestinal IR. Six groups of Lewis rats (n = 44) were studied: control, NECA (5′-N-ethyl carboxamide adenosine), IR …(30 minutes of intestinal ischemia, 2 hours of reperfusion), IR + NECA, IR + NECA + MRS1754 (A2B AR antagonist), IR + NECA + DPCPX (A1 AR antagonist). All substances were administered i.v. immediately after declamping of the superior mesenteric artery. Intravital microscopy was performed after 2 hours of reperfusion. Following IR we observed a significant increase of leukocyte adhesion in the intestinal submucosal venules and a reduced capillary perfusion within the muscular layers. NECA reduced leukocyte activation and improved capillary perfusion significantly. Administration of A2B AR antagonist completely reversed the NECA effect, whereas A1 AR inhibition only partially abolished the action of NECA. The data support the hypothesis that adenosine signalling is involved in intestinal IR injury. A2B AR may be more important than A1 AR because A2B AR inhibition by MRS1754 completely reversed the effect of the adenosine receptor agonist NECA. Show more

Keywords: Adenosine, adenosine receptor, intestine, microcirculation, intravital microscopy, ischemia, reperfusion, leukocyte adhesion, capillary perfusion, functional capillary density (FCD)

DOI: 10.3233/CH-141846

Citation: Clinical Hemorheology and Microcirculation, vol. 59, no. 3, pp. 257-265, 2015

Authors: Park, Jai-Wun | Shin, Eun-Seok | Ann, Soe Hee | Gödde, Martin | Park, Lea Song-I | Brachmann, Johannes | Vidal-Lopez, Silvia | Wierzbinski, Jan | Lam, Yat-Yin | Jung, Friedrich

Article Type: Research Article

Abstract: BACKGROUND: Although magnetocardiography (MCG) has been proposed as a non-invasive technique with high accuracy for functional diagnosis of myocardial injury, the validation of MCG against fractional flow reserve FFR in diagnosing coronary artery disease (CAD) has not yet been established. The goal of the study was to determine the diagnostic accuracy of MCG versus invasively determined FFR in patients with suspected or known CAD. METHODS: Forty seven patients with suspected CAD (35 men; mean age 69 years) who underwent coronary angiography and FFR measurement were enrolled. FFR ≤0.8 was considered to indicate significant myocardial ischemia. The change of ST-segment fluctuation …score from rest to stress was calculated from the MCG. In addition, two blinded cardiologists assessed MCG images that were visualized by post-processing method, bull's-eye mapping. RESULTS: The best cut-off value of the percent change of ST-segment fluctuation score was −39.0% with sensitivity of 86.7% and specificity of 73.9%. Sensitivity, specificity, diagnostic accuracy, and the area under the receiver-operator characteristics curve of bull's-eye mapping for the detection of significant CAD were 90.5%, 92.3%, 91.5%, and 0.914 on a patient basis and 90.0%, 93.8%, 92.3%, and 0.919 by coronary territory, respectively. CONCLUSIONS: MCG accurately detects functionally significant CAD as defined by using FFR, provides an assessment of ischemic status in agreement with the change of ST-segment fluctuation score, and accurately localizes the ischemic territory in bull's eye mapping. Therefore, MCG may provide an incremental value for prediction of myocardial ischemia non-invasively and safely in clinical practice with fast examination time. Show more

Keywords: Magnetocardiography, coronary artery disease, fractional flow reserve, ischemia

DOI: 10.3233/CH-141912

Citation: Clinical Hemorheology and Microcirculation, vol. 59, no. 3, pp. 267-281, 2015

Authors: Polak-Jonkisz, D. | Zwolinska, D. | Purzyc, L.

Article Type: Other

Keywords: RBCs, Caspase-3, PKC, chronic kidney disease

DOI: 10.3233/CH-141918

Citation: Clinical Hemorheology and Microcirculation, vol. 59, no. 3, pp. 283-285, 2015