Effects of sarpogrelate on blood viscosity.

The objective of the present study was to evaluate the effects and safety of sarpogrelate hydrochloride (sarpogrelate) in patients with elevated blood viscosity (BV), after 12 and 24 weeks of twice (BID) or thrice (TID) daily administrations of sarpogrelate (100 mg). The participants received oral sarpogrelate administration for 24 weeks and visited the hospital every 12 ± 2 week for blood viscosity measurements at shear rates of 5 and 300 s-1. The BV measured at shear rate of 5 s-1 in male patients decreased significantly from 18.91 cP at the baseline to 16.3 cP after 24 weeks of sarpogrelate administration (13.6 % drop, p < 0.001). The BV measured at 5 s-1 in female decreased more significantly from 17.5 cP at the baseline to 13.4 cP after 24 weeks of sarpogrelate administration (23.0 % drop, p < 0.001). In summary, sarpogrelate may be considered as a possible therapeutic option for improving BV in patients with elevated blood viscosity. In particular, the reduction of the low-shear BV with the help of a viscosity-reducing drug such as sarpogrelate may be considered as a potentially new pharmacological tool for microvascular disease.

Association of Carotid Artery Endothelial Signal Intensity Gradient with Unilateral Large Artery Ischemic Stroke.

BACKGROUND: Common carotid artery (CCA) and internal carotid artery (ICA) are aligned linearly, but their hemodynamic role in ischemic stroke has not been studied in depth. OBJECTIVES: We aimed to investigate whether CCA and ICA endothelial shear stress (ESS) could be associated with the ischemic stroke of large artery atherosclerosis (LAA). METHODS: We enrolled consecutive patients with unilateral ischemic stroke of LAA and healthy controls aged >60 years in the stroke center of Jeonbuk National University Hospital. All patients and controls were examined with carotid artery time-of-flight magnetic resonance angiography, and their endothelial signal intensity gradients (SIGs) were determined, as a measure of ESS. The effect of right or left unilateral stroke on the association between carotid artery endothelial SIG and ischemic stroke of LAA was assessed. RESULTS: In total, the results from 132 patients with ischemic stroke of LAA and 121 controls were analyzed. ICA endothelial SIG showed significant and independent associations with the same-sided unilateral ischemic stroke of LAA, even after adjusting for the potential confounders including carotid stenosis, whereas CCA endothelial SIG showed a significant association with the presence of the ischemic stroke of LAA. CONCLUSION: Although CCA and ICA are located with continuity, the hemodynamics and their roles in large artery ischemic stroke should be considered separately. Further studies are needed to delineate the pathophysiologic roles of ESS in CCA and ICA for large artery ischemic stroke.

Assessing the Appeal of Instagram Electronic Cigarette Refill Liquid Promotions and Warnings Among Young Adults: Mixed Methods Focus Group Study.

BACKGROUND: While marketing for electronic cigarette refill liquids (e-liquids) is widespread on Instagram, little is known about the post elements that create appeal among young adult Instagram users. Further information is needed to help shape regulatory strategies appropriate for social media. OBJECTIVE: This study examined young adult Instagram user perceptions of actual e-liquid marketing posts and US Food and Drug Administration (FDA)-mandated nicotine addiction warning statements on Instagram. METHODS: A series of 12 focus groups (n=69) were held with non-tobacco users, vapers, smokers, and dual users in Wisconsin between September and December 2018. Participants discussed the elements of posts that they found appealing or unappealing, in addition to completing a survey about each post and e-liquid. Focus group transcripts were analyzed by smoking status using a framework analysis approach. RESULTS: Although willingness to try e-liquids was highest among nicotine users, focus group discussions indicated that Instagram posts promoting e-liquids held appeal for individuals across smoking statuses. The primary elements that created appeal were the perceived trustworthiness of the Instagram account, attractive design and flavor visuals, and promotion of flavors and nicotine levels that met personal preferences. Post appeal was reduced by references to vaping subcultures, indicators that the post creator did not take nicotine addiction seriously, and FDA-mandated nicotine warning statements. Non-tobacco users were particularly drawn to posts featuring nicotine-free e-liquids with attractive visual designs and flavors known from foods. CONCLUSIONS: Young adults consider a broad range of elements in assessing the appeal of e-liquid marketing on Instagram, with minor but notable distinctions by smoking status. Non-tobacco users are uniquely drawn to nicotine-free e-liquids and are more deterred by the FDA's mandated nicotine addiction warning statements than those from other smoking statuses. This suggests that it may be possible to tailor policy interventions in a manner that helps to reduce novel uptake of vaping without significantly diminishing its potential harm-reduction benefits.

Serum nitric oxide level correlates with serum brain natriuretic peptide and whole blood viscosity in hemodialysis patients.

BACKGROUND: Nitric oxide (NO) is tonically synthesized by the vascular endothelium and known as a marker of vasodilatation and blood flow. As NO has a critical role in hemodynamics, NO may be associated with other hemodynamics-related factors including atrial natriuretic peptide (ANP), B-type natriuretic peptide (BNP) and whole blood viscosity (WBV). It has been reported that serum NO level increased in patients undergoing hemodialysis. However, there are few reports about the relationship between NO and hemodynamic parameters in hemodialysis patients. OBJECTIVE: We investigated the associations between serum levels of NO and other hemodynamics-related factors such as ANP, BNP and WBV in patients with hemodialysis. METHODS: NO, ANP, and BNP levels before hemodialysis were measured using ELISA method. We measured WBV in pre- and post-dialysis. RESULTS: Mean serum levels of NO, ANP, and BNP were 13.97 ±â€¯10.34 µg/mL, 198.85 ±â€¯61.56 pg/mL, and 1233.32 ±â€¯280.81 pg/mL, respectively in patients with hemodialysis. The mean WBV values at shear rates of 1, 5, and 300 s-1 for pre-dialyses were 168.5 ±â€¯62.5, 76.9 ±â€¯20.6, and 33.3 ±â€¯3.8 mP, respectively. Serum NO level was positively correlated with WBV at shear rates of 1, 5, and 300 s-1 at pre- and post-hemodialysis. There is a correlation between serum nitrite levels and the change of SBV during hemodialysis. Serum nitrite levels correlated with the serum BNP levels. ANP levels have a negative correlation with pre-dialytic WBV. However, BNP levels did not correlate with WBV during hemodialysis. CONCLUSIONS: WBV is linked to an imbalance in serum vasoactive substances in hemodialysis patients and can cause significant hemodynamic disturbance.

Hemorheological Alteration in Patients Clinically Diagnosed with Chronic Liver Diseases.

Since liver function is changed by chronic liver diseases, chronic liver disease can lead to different hemorheological alterations during the course of the progression. This study aims to compare alterations in whole blood viscosity in patients with chronic liver disease, focusing on the gender effect. Chronic liver diseases were classified into three categories by patient's history, serologic markers, and radiologic findings: nonalcoholic fatty liver disease (NAFLD) (n = 63), chronic viral hepatitis B and C (n = 50), and liver cirrhosis (LC) (n = 35). Whole blood viscosity was measured by automated scanning capillary tube viscometer, while liver stiffness was measured by transient elastography using FibroScan®. Both systolic and diastolic whole blood viscosities were significantly lower in patients with LC than NAFLD and chronic viral hepatitis (P < 0.001) in male patients, but not in female patients. In correlation analysis, there were inverse relationships between both systolic and diastolic whole blood viscosity and liver stiffness (systolic: r = -0.25, diastolic: r = -0.22). Whole blood viscosity was significantly lower in male patients with LC than NAFLD or chronic viral hepatitis. Our data suggest that whole blood viscosity test can become a useful tool for classifying chronic liver disease and determining the prognosis for different types of chronic liver diseases.

#Vapelife: An Exploratory Study of Electronic Cigarette Use and Promotion on Instagram.

BACKGROUND: The growth of social networking services has enabled the sharing of electronic cigarette opinions and experiences via user-generated content. OBJECTIVES: This exploratory study analyzed electronic cigarette content found on the visual social networking service, Instagram, in order to highlight public health challenges created by this content and support understanding of electronic cigarette promotion and usage. METHODS: A qualitative content analysis was performed on Instagram posts made with the hashtags #ecig or #vape in October 2014. Images, text, and hashtags from 85 posts (43 #ecig, 42 #vape) were analyzed. In addition, the total number of posts made with eight key electronic cigarette hashtags was recorded at four points between March 2014 and October 2015. RESULTS: The total number of #vape posts on Instagram grew by 4,163,274 during the study period, while #ecig posts increased by 741,916. Of the posts examined in-depth, corporate users made up over half of posts. No posts were critical of electronic cigarettes. Few mentioned electronic cigarettes in the context of health benefits. No posts included major brands, and mod style electronic cigarettes were mentioned or depicted in over half of posts. A majority of posts included hashtags expressing vaping identity and community. In addition, users mentioned novel practices such as sub-ohming. Conclusions/Importance: Instagram users in our sample characterized electronic cigarettes primarily as novel devices rather than equivalents to cigarettes. Further, hashtag communities and identities appear to be forming around vaping. Future research should consider the public health implications of these hashtags, as well as novel electronic cigarette practices.

Endothelial shear stress and blood viscosity in peripheral arterial disease.

This review examines the emerging role of endothelial shear stress (ESS) and blood viscosity on the initiation and progression of atherosclerosis in peripheral arterial disease. Among the variables determining ESS, blood viscosity has to date been the most overlooked by clinical researchers. Blood viscosity is a laboratory assessment that is minimally invasive and modifiable using pharmacologic therapy as well as by hemodilution. Monitoring and controlling blood viscosity not only modulates ESS, but also reduces peripheral vascular resistance and increases blood flow to the lower extremities.

Validation of Signal Intensity Gradient from TOF-MRA for Wall Shear Stress by Phase-Contrast MR.

To validate the correlation between the signal intensity gradient (SIG) from time-of-flight magnetic resonance angiography (TOF-MRA) and wall shear stress (WSS) determined by phase contrast magnetic resonance (PC-MR), we conducted both experimental and human studies. In the experimental study, we measured WSS in four tubes of different sizes with variable flow rates using PC-MR and TOF-MRA. The flow rates of water in the experimental study ranged from 0.06 to 12.75 mL/s, resulting in PC-WSS values between 0.1 and 1.6 dyne/cm2. The correlation between PC-WSS and SIG was statistically significant, showing a coefficient of 0.86 (P < 0.001, R2 = 0.75). The line fit provided the conversion equation as Y = 1.6287X - 1.1563 (Y = PC-WSS, X = SIG). For the human study, 28 subjects underwent TOF-MRA and PC-MR examinations of carotid and vertebral arteries. Arterial PC-WSS and SIG were determined in the same segment for each subject. The arterial PC-WSS ranged from 1.9 to 21.0 dyne/cm2. Both carotid and vertebral arteries showed significant correlations between PC-WSS and SIG, with coefficients of 0.85, 0.86, 0.91, and 0.81 in the right and left carotid and vertebral arteries, respectively. Our results show that SIG from TOF-MRA and SIG-WSS derived from the conversion equation provide concurrent in vivo hemodynamic information on arterial shear stress. This study was registered on ClinicalTrials.gov with the identifier NCT04585971 on October 14, 2020.

Effect of hydration on whole blood viscosity in firefighters.

CONTEXT: Cardiovascular disease (CVD) is the leading cause of on-duty death among firefighters, totaling 45% of on-duty fatalities. Heat stress and fluid losses can result in decreases in cardiac output of firefighters, despite sustained tachycardia and maximally elevated heart rate during emergencies. Measurements of whole blood viscosity (WBV) may serve as an independent biomarker of the hydration and dehydration states of on-duty firefighters. OBJECTIVE: The current pilot study investigates the effects of a strenuous firefighting simulation and subsequent rehydration on WBV and other biological metrics in nine healthy, nonsmoking firefighters to (1) determine whether dehydration and rehydration result in detectable changes in WBV and (2) compare WBV with the results from a range of conventional medical tests. DESIGN: The research team designed a single-center, unblinded pilot study. SETTING: Fire Training Division, 1900 Lind Ave SW, Renton, WA, 98057. PARTICIPANTS: Participants were 9 healthy, nonsmoking firefighters who were volunteers. OUTCOME MEASURE(S): Vital signs, traditional medical blood tests, and WBV were measured for each firefighter (1) at baseline, (2) after exercise but before rehydration with alkaline water, and (3) postexercise and after rehydration. Hematocrit (HCT), hemoglobin (Hb), and WBV increased after exercise and before rehydration. RESULTS: Dehydration during the mock fire drill resulted in elevated WBV at both low- and high-shear rates. HCT and Hb increased due to dehydration and hemoconcentration. Hb and HCT returned to baseline values after exercise and rehydration, and while WBV improved, baseline values were not restored. After exercise but before rehydration, WBV changes were significantly larger than HCT and Hb changes, suggesting the profound influence of hydration states on WBV. CONCLUSIONS: WBV measurements were better determinants of hydration states than HCT or Hb and should be performed to monitor the cardiovascular health of at-risk firefighters.

Self-Organization and Migration of Dielectric Barrier Discharge Filaments in Argon Gas Flow.

Observations of atmospheric-pressure dielectric barrier discharge are conducted through a water-filled electrode in atmospheric-pressure argon gas flow. Quasi-symmetric self-organized discharge filaments were observed. The streamers moved with the gas flow, and the migration velocity increased with increasing gas velocity.

Cardiovascular risks of anemia correction with erythrocyte stimulating agents: should blood viscosity be monitored for risk assessment?

To date, all major clinical trials for anemia correction using erythrocyte stimulating agents (ESAs) failed to show improved outcomes for cardiovascular disease (CVD), stroke, and vascular thrombosis. Even moderate elevations in hemoglobin (e.g., to 13 g/dL) using erythropoietin have been associated with significantly increased risk of thrombotic cardiovascular events and heart failure. This review presents a biophysical rationale for increased risk of CVD among certain patients treated with ESAs and suggests a risk management approach based on blood viscosity. Whole blood viscosity is a key determinant of the work of the heart, and elevated blood viscosity appears to be both a strong predictor of cardiovascular disease and an important pathophysiological factor in the development of atherothrombosis. Blood donation has been shown to reduce viscosity. Reflecting these findings, studies in male blood donors and in women of premenopausal age with regular menstruation have shown reduced incidence of cardiovascular events such as myocardial infarction, angina, stroke, and the requirement for procedures such as percutaneous transluminal coronary angioplasty and coronary artery bypass graft compared with non-donors and postmenopausal women, respectively. We propose that blood viscosity monitoring should be considered as part of a cardiovascular risk assessment, whenever an increased cardiovascular risk is detected and particularly in the context of anemia correction.

Homocysteine and pulsatility index of cerebral arteries.

BACKGROUND AND PURPOSE: A pulsatility index (PI) represents vascular resistance distal to an examined artery. The purpose of the present study was to evaluate an association between plasma total homocysteine (tHcy) and PIs of the cerebral arteries in patients with ischemic stroke. METHODS: Consecutive patients with ischemic stroke referred to a neurovascular ultrasound laboratory were evaluated from March 2007 to February 2008. PI was defined as (peak systolic velocity-end-diastolic velocity)/mean flow velocity as recommended. Transcranial Doppler was examined in both middle cerebral arteries and vertebral arteries, and basilar arteries. All patients with ischemic stroke were subdivided according to the presence of proximal internal carotid arterial steno-occlusion (ICS). RESULTS: The numbers of patients enrolled for the present analysis as ischemic stroke without and with ICS were 272 and 92, respectively. PIs measured in the cerebral arteries did not show a significant difference in the two groups, in spite of the fact that mean flow velocities of both basilar arteries and vertebral arteries were significantly elevated in the patients with ICS. Plasma tHcy was found to be independently associated with graded increases of PIs in all cerebral arteries in the patients without ICS, even adjusted for the potential confounders. However, there was no association between tHcy and PI in the patients with ICS. CONCLUSION: Plasma tHcy was directly associated with increased cerebral arterial resistance. But in clinical situations when the cerebral arterial hemodynamics were altered as in the patients with ICS, the effect of tHcy on arterial remodeling could be obscured.

From Apple to Werewolf: A content analysis of marketing for e-liquids on Instagram.

INTRODUCTION: With the growing popularity of refillable e-cigarettes and recent FDA regulatory action on e-liquid warning labels, e-liquids are an increasingly important area of study. At present, however, little is known about how e-liquids are marketed. This study examined e-liquid marketing on the visual social media platform Instagram, on which users have created significant amounts of e-cigarette related content. METHODS: A systematic, random sample of Instagram posts with either #eliquid or #ejuice was collected from the Instagram API during one week in May 2017 and in October 2017 using the Netlytic application. A final sample of 1000 posts was analyzed using qualitative content analysis to discern e-liquid themes, claims, promotions, and products promoted. RESULTS: Of the 1000 posts, 61.1% promoted e-liquid. These posts were most frequently made by vape shops and ambassadors/representatives. Almost 80% of promotional posts featured a flavored e-liquid. Posts focused largely on e-liquids tasting good (35.4%) or being cool/edgy (19.0%). Many posts made use of Instagram's visual nature to share creative label designs. Just over a third of posts made some claim about e-liquid benefits or quality, with smokeless tobacco claims being most common. Although posts most commonly originated from the United States, posts made from Indonesia and the United Kingdom were also common. CONCLUSIONS: E-liquid marketing on Instagram emphasizes positive experiences, personalization, and aspirational identities rather than explicit health and cessation claims. Appeal to youth is a significant concern based both on marketing strategies and the demographics of Instagram users.

Smoking cessation processes in low-SES women: the impact of time-varying pregnancy status, health care messages, stress, and health concerns.

UNLABELLED: We tracked smoking outcomes - quitting, stage of readiness, action, motivation, self-efficacy, and confidence - over time among 943 low-SES women smokers accrued in an earlier smoking cessation intervention trial conducted in public health clinics. We assessed outcomes at 2, 6, 12 and 18 months post-initial clinic visit. Controlling for baseline characteristics and earlier program participation, we used hierarchical linear modeling to assess how intervening life events - pregnancy and exposure to subsequent clinic smoking interventions - affected smoking outcomes directly and indirectly, through the mediators, perceived stress and health concerns. RESULTS: All longitudinal smoking outcomes were positively related to health concerns and negatively related to perceived stress. Pregnancy favorably influenced all smoking outcomes but confidence, but exposure to additional interventions affected only motivation. Health concerns and stress partially mediated the positive impact of pregnancy. CONCLUSION: Public health efforts targeted to low-SES women smokers should continue to emphasize the benefits of quitting smoking for health maintenance and incorporate more effective stress-coping mechanisms. Pregnancy increases abstinence, but preventing post-delivery relapse may require stress management and re-focusing of health concerns.

Reduced amputation rate with isovolemic hemodilution in critical limb ischemia patients.

AIMS: Critical limb ischemia (CLI) patients are characterized by intractable pain in spite of medication, non-healing ulcers, and gangrene. The objective of this study was to investigate whether or not isovolemic hemodilution treatment can reduce the rate of major amputations in CLI. METHODS: 28 patients were studied who had tissue loss on Rutherford Grade III, Category 5 or 6. The subjects were divided into two arms: standard-of-care, conventional therapy (CT) (n = 15) as a control group and hemodilution therapy (HT) (n = 13) as a study group. For the HT group, weekly isovolemic hemodilution was performed over 4 consecutive weeks, removing 250 ml of whole blood with the infusion of hydroxyl-ethyl starch solution. Blood viscosity, hematocrit, hemoglobin, ankle-brachial index, VA pain scale, time-to-amputation from admission, and survival time were measured. RESULTS: The mean Hct gradually decreased from 36.6 to 35.1, whereas the WBV at a shear rate of 1 s-1 significantly decreased from 18.2 to 10.5 during the same period. Subsequently, tissue oxygen delivery index, defined as the ratio of Hct to WBV at a shear rate of 1 s-1, increased from 24.4 to 37.0 by 51.7%, suggesting improvements in oxygen delivery in the patients. The average rate of lower limb major amputation in the control group was 93% (14/15), whereas that in the study group was 31% (4/13) (p = 0.001). Amputation-free median survival time and amputation-free 5-year survival rate in the control group were 1.2 months and 7%, while those in the study group were 30.2 months and 44% (p = 0.001). There were no adverse effects from repetitive hemodilution in the study group. CONCLUSIONS: Isovolemic hemodilution treatment of CLI patients was found to be well-tolerated and reduced the rate of major amputation resulting from the deterioration of CLI.

Changes in whole blood viscosity during hemodialysis and mortality in patients with end-stage renal disease.

Whole blood viscosity (WBV) plays a role in hemorheology and is determined by many factors such as red blood cell factors, plasma protein and blood volume. As WBV changes during hemodialysis, mortality may be due to changes in WBV in patients on hemodialysis. However, there are few prospective data on the relationship between changes in WBV and overall mortality in dialysis patients. We tried to investigate the correlations between values of WBV at variable shear rates before and after hemodialysis and overall or atherosclerosis-related mortality in patients with end-stage kidney disease.Forty-three patients receiving hemodialysis were enrolled in this study. In this 5.8-year prospective observational study, analyses of the effects of WBV at shear rates of 300 s-1 (systolic WBV; SBV), 5 s-1 (diastolic WBV5; DBV5), and 1 s-1 (diastolic WBV1; DBV1) during dialysis on all-cause and atherosclerotic mortality was performed.Among a total of 43 patients, 27 (62.7%) died over the course of the study. Thirteen deaths were caused by atherosclerotic events. A high degree of change in WBV at shear rates of 300 s-1 and 5 s-1 during hemodialysis (ΔSBV, ΔDBV5) was positively correlated with overall mortality (HR = 4.688, 95% confidence interval [CI], 1.269-17.319, p = 0.020; HR = 3.941, 95% CI, 1.057-14.701, p = 0.041, respectively). A high degree of change in diastolic blood pressure (ΔDBP) during hemodialysis was also positively correlated with overall mortality (HR = 3.035, 95% CI, 1.039-8.867, p = 0.042). However, comparative analysis between WBV at shear rates of 300 s-1, 5 s-1, and 1 s-1 and overall mortality did not reveal any significant relationships. Kaplan-Meier analysis revealed that the all-cause mortality was significantly higher in patients from a high degree of change of WBV at shear rates of 300 s-1, compared to those from the moderate or low degree of changes of WBV at shear rates of 300 s-1 (p = 0.020, log-rank test). Survival rate in high ΔDBP was lower than that of moderate or low ΔDBP group in Kaplan-Meier survival analysis (p = 0.004, log-rank test).Our data showed that a high degree of change in WBV at variable shear rates during hemodialysis might impact overall survival in patients with end-stage kidney disease. However, large-scale studies to evaluate the relationship of WBV with overall mortality and atherosclerotic mortality will be needed.

Direct Assessment of Wall Shear Stress by Signal Intensity Gradient from Time-of-Flight Magnetic Resonance Angiography.

The aim of the study was to calculate the arterial wall signal intensity gradient (SIG) from time-of-flight MR angiography (TOF-MRA) and represent arterial wall shear stress. We developed a new algorithm that uses signal intensity (SI) of a TOF-MRA to directly calculate the signal intensity gradient (SIG). The results from our phantom study showed that the TOF-MRA SIG could be used to distinguish the magnitude of blood flow rate as high (mean SIG ± SD, 2.2 ± 0.4 SI/mm for 12.5 ± 2.3 L/min) and low (0.9 ± 0.3 SI/mm for 8.5 ± 2.6 L/min) in vessels (p < 0.001). Additionally, we found that the TOF-MRA SIG values were highly correlated with various flow rates (ß = 0.96, p < 0.001). Remarkably, the correlation coefficient between the WSS obtained from the computational fluid dynamics (CFD) analysis and the TOF-MRA SIG was greater than 0.8 in each section at the carotid artery (p < 0.001 for all ß values). This new technique using TOF-MRA could enable the rapid calculation of the TOF-MRA SIG and thereby the WSS. Thus, the TOF-MRA SIG can provide clinicians with an accurate and efficient screening method for making rapid decisions on the risk of vascular disease for a patient in clinical practice.

Physiological flow analysis in significant human coronary artery stenoses.

To evaluate the local hemodynamics in flow limiting coronary lesions, computational hemodynamics was applied to a group of patients previously reported by Wilson et al. (1988) with representative pre-angioplasty stenosis geometry (minimal lesion size d(m)=0.95 mm; 68% mean diameter stenosis) and with measured values of coronary flow reserve (CFR) in the abnormal range (2.3+/-0.1). The computations were at mean flow rates (Q) of 50, 75 and 100 ml/min (the limit of our converged calculations). Computed mean pressure drops Deltap were approximately 9 mmHg for basal flow (50 ml/min), approximately 27 mmHg for elevated flow (100 ml/min) and increased to an extrapolated value of approximately 34 mmHg for hyperemic flow (115 ml/min), which led to a distal mean coronary pressure p(rh) of approximately 55 mmHg, a level known to cause ischemia in the subendocardium (Brown et al., 1984), and consistent with the occurrence of angina in the patients. Relatively high levels of wall shear stress were computed in the narrow throat region and ranged from about 600 to 1500 dyn/cm(2), with periodic (phase shifted) peak systolic values of about 3500 dyn/cm(2). In the distal vessel, the interaction between the separated shear layer wave, convected downstream by the core flow, and the wall shear layer flow, led to the formation of vortical flow cells along the distal vessel wall during the systolic phase where Reynolds numbers Re(e)(t) were higher. During the phasic vortical mode observed at both basal and elevated mean flow rates, wide variations in distal wall shear stress occurred, distal transmural pressures were depressed below throat levels, and pressure recovery was larger farther along the distal vessel. Along the constriction (convergent) and throat segments of the lesion the pulsatile flow field was principally quasi-steady before flow separation occurred. The flow regimes were complex in the narrow mean flow Reynolds number range Re(e)=100-230 and a frequency parameter of alphae=2.25. The shear layer flow disturbances diminished in strength due to viscous damping along the distal vessel at these relatively low values of Re(e), typical of flow through diseased epicardial coronary vessels. The distal hyperemic flow field was likely to be in an early stage of turbulent flow development during the peak systolic phase.

Influence of non-Newtonian viscosity of blood on microvascular impairment.

The present research investigated the role of blood viscosity on flow within a microvascular network to identify the conditions of blood flow stagnation. When the yield stress of blood was less than 0.005 Pa, there were no stagnant regions in the microvasculature. However, when the yield stress increased to 0.05 Pa, stagnant or reduced flow areas began to appear, which grew and expanded rapidly with further increase in the yield stress. Thus, the yield stress determined from blood viscosity profile of a patient can be utilized to evaluate the risk of circulatory impairment.

Reduction of low-density lipoprotein cholesterol, plasma viscosity, and whole blood viscosity by the application of pulsed corona discharges and filtration.

The present study investigated the feasibility of applying pulsed corona discharges to blood plasma to reduce the viscosity of blood plasma and whole blood. Blood plasma was separated from blood cells, treated with corona discharges, and filtered before it was re-mixed with blood cells. Plasma viscosity (PV), whole blood viscosity (WBV), and low-density lipoprotein (LDL)-c concentration were measured before and after the corona treatment and filtration. Both PV and WBV increased in the case of the corona treatment only, whereas both of them decreased in the case of the corona treatment plus filtration. In particular, the LDL-c decreased in the case of the corona treatment plus filtration by 31.5% from the baseline value. The effect of the corona treatment on the reduction of the WBV was significant at low shear rates, but not at high shear rates, suggesting that the precipitation of the molecules in blood plasma by the corona treatment and subsequent removal may suppress the aggregation of erythrocytes and improve rheological properties of blood.