Endothelial shear stress and blood viscosity in peripheral arterial disease

Biophysical and Biochemical Roles of Shear Stress on Endothelium: A Revisit and New Insights

Hemodynamic shear stress, the frictional force exerted by blood flow on the endothelium, mediates vascular homeostasis. This review examines the biophysical nature and biochemical effects of shear stress on endothelial cells, with a particular focus on its impact on cardiovascular pathophysiology. Atherosclerosis develops preferentially at arterial branches and curvatures, where disturbed flow patterns are most prevalent. The review also highlights the range of shear stress across diverse human arteries and its temporal variations, including aging-related alterations. This review presents a summary of the critical mechanosensors and flow-sensitive effectors that respond to shear stress, along with the downstream cellular events that they regulate. The review evaluates experimental models for studying shear stress in vitro and in vivo, as well as their potential limitations. The review discusses strategies targeting shear stress, including pharmacological approaches, physiological means, surgical interventions, and gene therapies. Furthermore, the review addresses emerging perspectives in hemodynamic research, including single-cell sequencing, spatial omics, metabolomics, and multiomics technologies. By integrating the biophysical and biochemical aspects of shear stress, this review offers insights into the complex interplay between hemodynamics and endothelial homeostasis at the preclinical and clinical levels.

Remodeling of the brain angioarchitecture in experimental chronic neurodegeneration

Chronic neurodegenerative diseases are characterized by substantial inflammation with putative impairment of the brain vasculature also commonly observed. To address effects of chronic neurodegeneration on the regional vasculature under experimentally controlled circumstances, the glutamate receptor agonist ibotenic acid was injected into striatum of adult rats, which causes excitotoxicity in the substantia nigra pars reticulata (SNpr) due to imbalance between inhibitory inputs from the striatum and excitatory signals from the subthalamic nucleus. Brains were examined at 28 days (short-term neurodegeneration) and 91 days (long-term neurodegeneration) and analyzed for vascular remodeling taking both 2D and 3D approaches, the latter involving confocal microscopy of optically cleared samples combined with machine learning-based image analysis. Crysectioned and microdissected samples were analyzed for protein and gene expression respectively. The resulting neurodegeneration was accompanied by regional tissue loss and inflammation. The 3D analysis of the degenerating SNpr revealed substantial changes of the vasculature with higher density, increased diameter, and number of tortuous vessels already after 28 days, evidently continuing at 91 days. Interestingly, the vascular remodeling changes occurred without changes in the expression of endothelial tight junction proteins, vascular basement membrane proteins, or markers of angiogenesis. We propose that remodeling of the vasculature in neurodegeneration occurs due to regional tissue atrophy, which leaves the vasculature operating but prone to additional pathologies.

Impact of Systolic Blood Viscosity on Deep White Matter Hyperintensities in Patients With Acute Ischemic Stroke

BACKGROUND

Elevated blood viscosity (BV), a critical determinant in blood rheology, is a contributing factor in cerebrovascular diseases. The specific influence of BV on small vessel disease burden remains unexplored. This study aims to examine the relationship between BV and regional white matter hyperintensity (WMH) volume in patients with acute ischemic stroke.

METHODS AND RESULTS

We enrolled a cohort of 302 patients with acute ischemic stroke or transient ischemic attack who were admitted to a hospital within 7 days of symptom onset in this study. We measured whole BV using a scanning capillary-tube viscometer and categorized systolic blood viscosity into 3 groups based on established references. We quantified and normalized WMH volumes using automated localization and segmentation software by NEUROPHET Inc. We performed multivariable logistic regression analysis to assess the correlation between systolic BV and WMH. The mean subject age was 66.7±13.4 years, and 38.7% (n=117) of the participants were female. Among a total of 302 patients, patients with higher deep WMH volume (T3) were typically older and had an atrial fibrillation, strokes of cardioembolic or undetermined cause, elevated levels of C-reactive protein, diastolic blood viscosity and systolic BV. A multivariable adjustment revealed a significant association between high systolic BV and increased deep-WMH volume (odds ratio [OR], 2.636 [95% CI, 1.225-5.673]).

CONCLUSIONS

Elevated systolic BV is more likely to be associated with deep WMH volume in patients with acute ischemic stroke or transient ischemic attack. These findings reveal novel therapeutic strategies focusing on blood rheology to enhance cerebral microcirculation in stroke management.

The MAPH Score Predicts Coronary Slow Flow. A Retrospective Case-Controlled Study

AIM

The MAPH score is a new score that combines mean platelet volume (MPV), hematocrit, and total protein, which are markers of whole blood viscosity (WBV). We aimed to investigate the relationship between the MAPH score and the coronary slow flow phenomenon (CSF).

MATERIAL AND METHODS

A total of 201 patients were included in the study. 105 had CSF and 96 had normal coronary flow (NCF). Coronary flow was measured by the Thrombolysis in Myocardial Infarction frame count (TFC) method. The patients' MPV, age, hematocrit, and total protein were recorded. High (HSR) and low shear rates (LSR) were calculated, based on total protein and hematocrit values. Cut-off values for CSF were determined using the Youden's index, and the score was determined as 0 or 1 according to the cut-off values. The sum of these scores was the MAPH score.

RESULTS

The mean age of the patients included in the study was 51.1±7.9 (n=201, 54.2 % male). Hyperlipidemia, DM, and HT rates of both groups were similar, but the mean age of the CSF group was higher (p=0.773; p=0.549; p=0.848; p <0.001, respectively). Total protein, MPV, hematocrit, HSR and LSR were higher in the CSF group (p< 0.001, for all values). Comparative receiver operating characteristic (ROC) curve analysis showed that the performance of the MAPH score in predicting CSF is better than the performance of these parameters separately.

CONCLUSION

A new score, the MAPH score, may be used to identify the presence of CSF.

Skipping breakfast does not accelerate the hyperglycemia-induced endothelial dysfunction but reduces blood flow of the brachial artery in young men

PURPOSE

Postprandial hyperglycemia is assumed to have a negative impact on flow-mediated dilation (FMD), an index of endothelial function, and blood flow of the peripheral conduit arteries. This study aimed to determine whether the enhancement of postprandial hyperglycemia by skipping breakfast accelerates endothelial dysfunction and reduces the blood flow in the brachial artery in young men.

METHODS

Using a randomized cross-over design, ten healthy men completed two trials: with and without breakfast (Eating and Fasting trials, respectively). Venous blood sampling and brachial FMD tests were conducted before, 30, 60, 90, and 120 min after a 75-g oral glucose tolerance test (OGTT).

RESULTS

Skipping breakfast boosted post-OGTT glucose levels than having breakfast (P = 0.01). The magnitude of the decrease in FMD via OGTT did not vary between trials (main effect of trial P = 0.55). Although brachial blood flow tended to decrease after OGTT in both trials (interaction and main effect of time P = 0.61 and P = 0.054, respectively), the decrease in blood flow following OGTT was greater in the Fasting trial than in the Eating trial (main effect of trial, mean difference =  - 15.8 mL/min [95%CI =  - 25.6 to - 6.0 mL/min], P < 0.01).

CONCLUSION

Skipping breakfast did not enhance the magnitude of the decrease in FMD following glucose loading, but did accelerate hyperglycemia-induced reduction in brachial blood flow. Current findings suggest that even missing one breakfast has negative impacts on the blood flow regulation of the peripheral conduit arteries in young men who habitually eat breakfast.

A BODIPY-based fluorescent probe for simultaneous detection of H2O2 and viscosity during the pyroptosis process

A dual functional BODIPY fluorescent probe was developed for simultaneous detection of H2O2 and viscosity, by collecting fluorescence from 800-1100 nm and 550-750 nm, respectively. Bioimaging based on the probe shows that H2O2 accumulates and cytoplasmic viscosity increases during the palmitic acid (PA)-induced pyroptosis process.

Inflammatory Biomarkers and Blood Physical Property Transformations Following On-Pump Coronary Artery Bypass Graft Surgery

OBJECTIVE

This study aimed to compare the hemorheological and inflammatory changes before and after coronary artery bypass graft (CABG) surgery, as factors such as hypothermia, hemodilution, transfusion, and other variables affect blood viscosity and inflammation during the procedure.

METHODS

A total of 25 patients who underwent CABG surgery were enrolled in this study. Whole blood was collected just before the CABG (D0), 2 days after surgery (D2), and 5 days after surgery (D5). The plasma viscosity (PV) and whole blood viscosity (WBV) were measured at shear rates ranging from 0.1 to 1000 s-1 using a rheometer, and the mean values were compared. Inflammatory markers were also assessed and analyzed in relation to the hemorheological changes.

RESULTS

Compared with the baseline values, the PV significantly increased after 5 days. WBV showed a significant increase on day 2 and after 5 days. The WBV and fibrinogen were significantly correlated on day 2 and day 5 but not before surgery. Inflammatory markers such as CRP, WBC, platelets, and fibrinogen also demonstrated notable changes in relation to the hemorheological alterations.

CONCLUSIONS

This study highlights the crucial finding that hyperviscosity, characterized by elevated PV and WBV, persists for almost one week after on-pump CABG surgery. Understanding the interplay between inflammation and hemorheological properties during the postoperative period is crucial for optimizing patient care. Future research should focus on exploring the underlying mechanisms and potential therapeutic interventions to mitigate the impact of inflammation on blood viscosity and improve patient outcomes following CABG surgery.

Magnetically assisted soft milli-tools for occluded lumen morphology detection

Methodologies based on intravascular imaging have revolutionized the diagnosis and treatment of endovascular diseases. However, current methods are limited in detecting, i.e., visualizing and crossing, complicated occluded vessels. Therefore, we propose a miniature soft tool comprising a magnet-assisted active deformation segment (ADS) and a fluid drag-driven segment (FDS) to visualize and cross the occlusions with various morphologies. First, via soft-bodied deformation and interaction, the ADS could visualize the structure details of partial occlusions with features as small as 0.5 millimeters. Then, by leveraging the fluidic drag from the pulsatile flow, the FDS could automatically detect an entry point selectively from severe occlusions with complicated microchannels whose diameters are down to 0.2 millimeters. The functions have been validated in both biologically relevant phantoms and organs ex vivo. This soft tool could help enhance the efficacy of minimally invasive medicine for the diagnosis and treatment of occlusions in various circulatory systems.

Rheocarna® therapy after distal bypass surgery

Objectives: Rheocarna® therapy has recently been reported to improve peripherally measured blood flow as an adjuvant treatment after revascularization in patients with chronic limb-threatening ischemia. We investigated whether skin perfusion pressure and continuous walking distance were improved by performing Rheocarna® therapy after distal bypass surgery. Methods: This study included 10 patients who underwent Rheocarna® therapy after distal bypass surgery between June 2022 and March 2023. Rheocarna® therapy was performed five times after distal bypass surgery, and the skin perfusion pressure and continuous walking distance after distal bypass surgery were compared with those after Rheocarna® therapy. Results: The average age was 74.7 years, and nine patients (90%) were male. All patients were undergoing dialysis, with an average of 14.5 years of dialysis history. There were six patients (60%) with diabetes mellitus and five (50%) with hyperlipidemia. The ankle-brachial index was 0.62 ± 0.36 before distal bypass surgery and 0.936 ± 0.16 after Rheocarna® therapy, indicating a significant increase (p = 0.0117). Skin perfusion pressure dorsalis pedis was 71.5 ± 27.0 mmHg after Rheocarna® therapy, showing a marked increase from the preoperative value (p = 0.0020). Skin perfusion pressure planta pedis was 65.0 ± 26.3 mmHg after Rheocarna® therapy, which was a significant increase from the preoperative value (p = 0.0293). The continuous walking distance was 78.5 ± 102.7 m after the Rheocarna® therapy, which was a significant increase from the preoperative value (p = 0.0039). Conclusion: The skin perfusion pressure and continuous walking distance were significantly improved by Rheocarna® therapy after distal bypass surgery.

Full-scale numerical simulation of hemodynamics based on left ventricular assist device

Ventricular assist devices have been widely used and accepted to treat patients with end-stage heart failure. The role of VAD is to improve circulatory dysfunction or temporarily maintain the circulatory status of patients. In order to be closer to the medical practice, a multi-Domain model of the left ventricular coupled axial flow artificial heart was considered to study the effect of its hemodynamics on the aorta. Because whether LVAD itself was connected between the left ventricular apex and the ascending aorta by catheter in the loop was not very important for the analysis of simulation results, on the premise of ensuring the multi-Domain simulation, the simulation data of the import and export ends of LVAD were imported to simplify the model. In this paper, the hemodynamic parameters in the ascending aorta, such as blood flow velocity vector, wall shear stress distribution, vorticity current intensity, vorticity flow generation, etc., have been calculated. The numerical conclusion of this study showed the vorticity intensity under LVAD was significantly higher than that under patients' conditions and the overall condition is similar to that of a healthy ventricular spin, which can improve heart failure patients' condition while minimizing other pitfalls. In addition, high velocity blood flow during left ventricular assist surgery is mainly concentrated near the lining of the ascending aorta lumen. What's more, the paper proposes to use Q criterion to determine the generation of vorticity flow. The Q criterion of LVAD is much higher than that of patients with heart failure, and the closer the LVAD is to the wall of the ascending aorta, the greater the Q criterion is. All these are beneficial to the effectiveness of LVAD in the treatment of heart failure patients and provide clinical suggestions for the LVAD implantation in clinical practice.

Association of blood viscosity and device-free days among hospitalized patients with COVID-19

BACKGROUND

Increased estimated whole blood viscosity (eWBV) predicts higher mortality in patients hospitalized for coronavirus disease 2019 (COVID-19). This study assesses whether eWBV is an early predictor of non-fatal outcomes among patients hospitalized for acute COVID-19 infection.

METHODS

This retrospective cohort study included 9278 hospitalized COVID-19 patients diagnosed within 48 h of admission between February 27, 2020 to November 20, 2021 within the Mount Sinai Health System in New York City. Patients with missing values for major covariates, discharge information, and those who failed to meet the criteria for the non-Newtonian blood model were excluded. 5621 participants were included in the main analysis. Additional analyses were performed separately for 4352 participants who had measurements of white blood cell count, C-reactive protein and D-dimer. Participants were divided into quartiles based on estimated high-shear blood viscosity (eHSBV) and estimated low-shear blood viscosity (eLSBV). Blood viscosity was calculated using the Walburn-Schneck model. The primary outcome was evaluated as an ordinal scale indicating the number of days free of respiratory organ support through day 21, and those who died in-hospital were assigned a value of -1. Multivariate cumulative logistic regression was conducted to evaluate the association between quartiles of eWBV and events.

RESULTS

Among 5621 participants, 3459 (61.5%) were male with mean age of 63.2 (SD 17.1) years. The linear modeling yielded an adjusted odds ratio (aOR) of 0.68 (95% CI 0.59-0.79, p value < 0.001) per 1 centipoise increase in eHSBV.

CONCLUSIONS

Among hospitalized patients with COVID-19, elevated eHSBV and eLSBV at presentation were associated with an increased need for respiratory organ support at 21 days. These findings are highly relevant, as they demonstrate the utility of eWBV in identifying hospitalized patients with acute COVID-19 infection at increased risk for non-fatal outcomes in early stages of the disease.

Modelling of thrombus formation using smoothed particle hydrodynamics method

In this paper a novel model, based on the smoothed particle hydrodynamics (SPH) method, is proposed to simulate thrombus formation. This describes the main phases of the coagulative cascade through the balance of four biochemical species and three type of platelets. SPH particles can switch from fluid to solid phase when specific biochemical and physical conditions are satisfied. The interaction between blood and the forming blood clot is easily handled by an innovative monolithic FSI approach. Fluid-solid coupling is modelled by introducing elastic binds between solid particles, without requiring detention and management of the interface between the two media. The proposed model is able to realistically reproduce the thromboembolic process, as confirmed by the comparison of numerical results with experimental data available in the literature.

Rheocarna® as an alternative therapeutic option for patients with chronic limb-threatening ischemia: A case report

Recently, a new low-density lipoprotein apheresis device (Rheocarna^®; Kaneka Corporation, Osaka, Japan), a blood purification therapy, was approved in Japan for managing chronic limb-threatening ischemia with refractory ulcers. Here, we describe a case of chronic limb-threatening ischemia that was treated with the Rheocarna. A 65-year-old Asian man with an ulcer on the right heel was admitted to our hospital. Angiography revealed chronic total occlusion with severe calcification of the anterior tibial, peroneal, and posterior tibial arteries. The patient underwent distal bypass of the saphenous vein; however, the bypass was occluded in the early postoperative period. The Rheocarna was used, and the ulcers improved significantly postoperatively. Although endovascular treatment was eventually performed on the occluded bypass graft to completely heal the ulcer, the Rheocarna could be an alternative treatment option in challenging cases of chronic limb-threatening ischemia.

Relationship between blood viscosity and existence and severity of carotid artery plaque

BACKGROUND

Accumulating evidence shows that the increase in blood viscosity (BV) is an independent risk factor for atherosclerosis and its related diseases, but as far as we know, there are few studies on the relationship between blood viscosity and carotid plaque severity. Therefore, we aimed to investigate the relationship between blood viscosity and the presence of carotid plaques, and further explore its relationship with the severity of carotid plaques.

METHODS

We retrospectively analyzed the data of consecutive subjects in the physical examination center of the Affiliated Hospital of Ningbo University Medical College from January 2022 to May 2022.The parameters of blood viscosity include the whole blood viscosity (WBV) at high, middle, and low shear rate, plasma viscosity (PV), hematocrit (HCT), rigidity "k", rigidity index (RI), aggregation index (AI) and electrophoresis rate (ER), and standardized BV calculated by Quemada's equation were included in the study. Carotid plaque score (CPS) was used to measure the severity of carotid artery disease, and participants were divided into mild, moderate, and severe groups according to the quartile of the score. Independent samples t-test and one-way ANOVA were used to compare normally distributed continuous variables between two or more independent groups, respectively. Binary logistic regression was used to evaluate the risk factors of carotid plaque.

RESULTS

314 men were enrolled in the study, of which 165 participants were diagnosed with Carotid artery plaque (CAP) (66.9%). Compared with the CAP- group, the WBV and PV of the CAP+group decreased, but the difference only existed in the PV (p = 0.001). However, standardized BV values (HCT set at 0.45) were higher in the CAP+group than in the CAP- group (3.8643±0.35431vs 3.9542±0.64871, p = 0.188). Regarding the rigidity and aggregation of RBC, the parameters including rigidity "k", RI, AI and ER increased in the CAP+group compared with the CAP- group. The difference was statistically significant in k and ER (p = 0.04, p = 0.009). To assess the severity of carotid plaque, we divided the participants into mild, moderate, and severe groups by using the tertile of CPS value. The mild group was defined as CPS≤0.5 (n = 108), the moderate group as 0.5 <  CPS≤1.7 (n = 105), and the severe group as CPS >  1.7 (n = 101). It was found that WBV and PV decreased with the increase of plaque severity, but the difference among the three groups was significant in PV (F = 8.073, p <  0.0001). In addition, with the severity of plaque from mild to severe, standardized BV gradually increased, which were 3.8611±0.34845, 3.8757±0.36637, 3.9007±0.38353 respectively. The difference between the groups was close to statistically significant (F = 2.438, p = 0.089). The values of parameters describing erythrocyte aggregation and rigidity increased among the mild, moderate, and severe groups. The difference was statistically significant in RBC rigidity "k" and ER of RBC (F = 3.863, p = 0.022; F = 5.897, p = 0.003, respectively).

CONCLUSION

Increased blood viscosity is a risk factor for carotid plaque, but its increase may be hidden by decreased hematocrit. Therefore, it is necessary to comprehensively analyze various parameters of blood viscosity, such as the standardized BV calculated by Quemada's equation, which may provide more useful reference value.

Relationship between blood viscosity and thrombus burden in ST-segment elevation myocardial infarction

BACKGROUND

İncreased whole blood viscosity (WBV) is associated with increased infarct area, impaired microvascular circulation and mortality in patients with ST-elevation myocardial infarction (STEMI).

OBJECTIVES

We aimed to analyze the association between the WBV and thrombus burden (TB) in STEMI patients.

METHODS

This cross-sectional study included 167 STEMI patients who received primary percutaneous coronary intervention. WBV values were assessed using hematocrit and total protein values, and low shear rate(LSR) and high shear rate(HSR) were calculated. Angiographic TB was assessed according to the definition of the Thrombolysis in Myocardial Infarction (TIMI) study group. The cases were dichotomized into low TB (grade 1-3) (n = 87) and high TB (grade 4-5) (n = 80) groups.

RESULTS

The mean HSR and LSR values of the high TB group were significantly increased compared to the low TB group (p < 0.001, for each). In ROC analysis,for prediction of TB, a cut-off value of 3.83 WBV for HSR had a 71% sensitivity and a 60.7% specificity, and a cut-off value of 21 WBV for LSR had a 70% sensitivity and 59.9% specificity (p < 0.001,for each). Multivariate regression analysis showed that both HSR (OR = 2.408;p=0.020) and LSR (OR = 1.055;p=0.021) were independent predictors for high TB.

CONCLUSION

İncreased WBV was an independent predictor for the presence of high TB in patients with STEMI.

Sex-related differences in endothelial function and blood viscosity in the elderly population

Elderly represents a growing population and cardiovascular diseases (CVD) is one of the leading causes of mortality in this population. Sex differences are involved in CVD with middle-aged males being at higher risk than females. After menopause, females are no longer protected by hormones and the role of sex on cardiovascular parameters involved in CVD, such as endothelial function and blood viscosity, is still unclear. The purpose of this study was to investigate the effect of sex on endothelial function, blood viscosity and CVD in elderly. Clinical investigation and blood analyses were performed on 182 (93 females and 89 males) elderly participants (mean age: 75.83 ± 1.22). Health status of participants were classified. Sex differences in endothelial function, blood viscosity, high density lipoprotein (HDL), hematocrit, and red blood cell (RBC) aggregation were assessed. CVD prevalence was higher in males (27.0%) than in females (5.4%) (p < 0.001). Females had higher vasoreactivity (p = 0.014) and HDL (p < 0.001) level than males. Blood viscosity was higher in males than in females at any shear rate (p < 0.001). Hematocrit was greater in males than in females (p < 0.001) while RBC aggregation did not differ between the two populations. To conclude, females have less CVD than age-matched males that might be due to their greater vascular function and lower blood viscosity.

Hemodilution on microvascular oxygen delivery potential of the blood during coronary bypass surgery

PURPOSE

The hematocrit-to-whole blood viscosity ratio (Hct/WBV) reflects the blood O2 delivery potential (O2-DP). WBV is variable to the dynamic vascular shear rate (SR), 1-5/s at microcirculation and 300/s at larger vessels. To estimate the impact of hemodilution on the blood O2-DP to the myocardium, we analyzed the hemodilution-induced change of Hct/WBV at SR 5/s (Hct/WBV5) during off-pump coronary bypass (OPCAB) surgery.

METHODS

During OPCAB surgery (n = 21), 10% acute normovolemic hemodilution (HD 10%) was applied. Arterial blood samples were taken: one before and two after HD 10%. One of which after HD 10% underwent an additional 33% in vitro hemodilution (reaching 40% hemodilution in total, HD 40%). WBV of all blood samples was determined using a scan-capillary tube viscometer (Hemovister™). The changes of Hct/WBV5 were analyzed as a primary measure of the study and compared with those of Hct/WBV at SR 300/s (Hct/WBV300).

RESULTS

Median[IQR] of Hct/WBV5 [3.5 (2.8-4.2)%/cPoise] was significantly increased by HD 10 and HD 40% [3.6 (3.2-4.6)%/cPoise and 4.2 (3.3-5.2)%/cPoise, respectively, all P < 0.001], but the degrees of changes after HD 10 and HD 40% were not different. Median[IQR] of Hct/WBV300 [10.3(8.6‒10.8)%/cPoise] was not changed by HD 10% [10.3(9.1-11.1)%/cPoise], but it was significantly decreased by HD 40% [8.4(7.4‒9.2)%/cPoise, P < 0.001].

CONCLUSION

The increased Hct/WBV5 suggests that 10-40% hemodilution improves the blood O2-DP to the myocardium during OPCAB surgery. The SR-specific discrepancy in Hct/WBV changes advocates using microvascular WBV and Hct/WBV to evaluate the blood O2-DP changes to the myocardium. Further study is warranted to assess the actual changes in myocardial O2 delivery.

Evaluation of the relationship between plasma viscosity and selected menopausal symptoms using the Menopause Rating Scale

OBJECTIVE

The aim of this study was to investigate whether whole blood viscosity and plasma viscosity are associated with the severity of postmenopausal symptoms using the Menopause Rating Scale (MRS).

METHODS

This study included 108 postmenopausal women admitted to menopause clinics. Participants were divided into two groups according to their MRS scores. Groups 1 (n = 52) and 2 (n = 56) were composed of healthy postmenopausal women with MRS scores of <14 and ≥14 points, respectively. The clinical findings and hemorheological parameters were compared between the two groups.

RESULTS

Comparing plasma viscosity levels between the two groups showed that group 1 had 1.25 ± 0.08 centipoise, whereas group 2 had 1.30 ± 0.10 centipoise ( P = 0.03). The difference in plasma viscosity between the two groups persisted after adjustment for age (1.24 ± 0.08 vs 1.31 ± 0.10; P < 0.001). Plasma viscosity was also significantly correlated with age ( r = 0.384, P < 0.001), menopausal duration ( r = 0.362, P < 0.001), and urogenital symptoms ( r = 410, P < 0.001).

CONCLUSIONS

Increased plasma viscosity levels were significantly associated with selected postmenopausal symptoms, independent of age.

Association of Blood Viscosity With Mortality Among Patients Hospitalized With COVID-19

Background

Coronavirus disease-2019 (COVID-19) is characterized by a dysfunctional immune response and abnormal blood rheology that contribute to endothelial dysfunction and thrombotic complications. Whole blood viscosity (WBV) is a clinically validated measure of blood rheology and an established predictor of cardiovascular risk. We hypothesize that increased WBV is associated with mortality among patients hospitalized with COVID-19.

Objectives

This study sought to determine the association between estimated BV (eBV) and mortality among hospitalized COVID-19 patients.

Methods

The study population included 5,621 hospitalized COVID-19 patients at the Mount Sinai Health System from February 27, 2020, to November 27, 2021. eBV was calculated using the Walburn-Schneck model. Multivariate Cox proportional hazards models were used to evaluate the association between eBV and mortality. Considered covariates included age, sex, race, cardiovascular and metabolic comorbidities, in-house pharmacotherapy, and baseline inflammatory biomarkers.

Results

Estimated high-shear BV (eHSBV) and estimated low-shear BV were associated with increased in-hospital mortality. One-centipoise increases in eHSBV and estimated low-shear BV were associated with a 36.0% and 7.0% increase in death, respectively (P < 0.001). Compared with participants in the lowest quartile of eHSBV, those in the highest quartile of eHSBV had higher mortality (adjusted HR: 1.53; 95% CI: 1.27-1.84). The association was consistent among multiple subgroups, notably among patients without any comorbidities (adjusted HR: 1.69; 95% CI: 1.28-2.22).

Conclusions

Among hospitalized COVID-19 patients, increased eBV is significantly associated with higher mortality. This suggests that eBV can prognosticate patient outcomes in earlier stages of COVID-19, and that future therapeutics aimed at reducing WBV should be evaluated.

Excessive platelet inhibition following Pipeline embolization of intracranial aneurysms

BACKGROUND

High levels of platelet inhibition have been associated with hemorrhagic complications following Pipeline embolization of intracranial aneurysms. We therefore titrate clopidogrel dosing to maintain a moderate level of platelet inhibition using the VerifyNow P2Y12 assay. However, many patients demonstrate dramatic increases in platelet inhibition following treatment despite being on a consistent antiplatelet regimen. We therefore elected to explore the incidence of this phenomenon and possible predisposing factors.

METHODS

All successful Pipeline aneurysm treatments performed at our institution from 2011 to 2019 with moderate procedure-day platelet inhibition levels as indicated by a VerifyNow PRU of 60-235 were included. Patients who received glycoprotein IIb/IIIa inhibitors and those treated for ruptured/symptomatic lesions were excluded. The incidence of excessive platelet inhibition defined by a PRU<60 within 8 weeks of treatment was noted. Multivariable logistic regression was performed to determined independent predictors of the phenomenon.

RESULTS

Some 190 treatments were performed in 178 qualifying patients. A post-procedure PRU <60 occurred following 79% of treatments, documented on average after 8.5 (range 1-47) days. A higher procedure day hematocrit level (P=0.003, OR 1.09, 95% CI 1.029 to 1.152) was an independent predictor of reaching a PRU <60, while intra-procedural midazolam exposure (P=0.044, OR 0.44, 95% CI 0.201 to 0.980) and a higher procedure-day PRU (P=0.047, OR 0.99, 95% CI 0.982 to 1.000) were associated with a reduced odds. Time-since-procedure and hematocrit levels were associated with excessive platelet inhibition when excluding patients who initially demonstrated hyperresponse.

CONCLUSION

Elevations in platelet inhibition were frequently observed following flow diversion with Pipeline.

Hypoxia and hemorheological properties in older individuals

Hypoxia is caused by insufficient oxygen availability for the organism leading to reduced oxygen delivery to tissues and cells. It has been regarded as a severe threat to human health and it is indeed implicated in pathophysiological mechanisms involved in the development and progression of many diseases. Nevertheless, the potential of controlled hypoxia interventions (i.e. hypoxia conditioning) for improving cardio-vascular health is gaining increased attention. However, blood rheology is often a forgotten factor for vascular health while aging and hypoxia exposure are both suspected to alter hemorheological properties. These changes in blood rheology may influence the benefits-risks balance of hypoxia exposure in older individuals. The benefits of hypoxia exposure for vascular health are mainly reported for healthy populations and the combined impact of aging and hypoxia on blood rheology could therefore be deleterious in older individuals. This review discusses evidence of hypoxia-related and aging-related changes in blood viscosity and its determinants. It draws upon an extensive literature search on the effects of hypoxia/altitude and aging on blood rheology. Aging increases blood viscosity mainly through a rise in plasma viscosity, red blood cell (RBC) aggregation and a decrease in RBC deformability. Hypoxia also causes an increase in RBC aggregation and plasma viscosity. In addition, hypoxia exposure may increase hematocrit and modulate RBC deformability, depending on the hypoxic dose, i.e, beneficial effect of intermittent hypoxia with moderate dose vs deleterious effect of chronic continuous or intermittent hypoxia or if the hypoxic dose is too high. Special attention is directed toward the risks vs. benefits of hemorheological changes during hypoxia exposure in older individuals, and its clinical relevance for vascular disorders.

Mechanoregulation of Vascular Endothelial Growth Factor Receptor 2 in Angiogenesis

The endothelial cells that compose the vascular system in the body display a wide range of mechanotransductive behaviors and responses to biomechanical stimuli, which act in concert to control overall blood vessel structure and function. Such mechanosensitive activities allow blood vessels to constrict, dilate, grow, or remodel as needed during development as well as normal physiological functions, and the same processes can be dysregulated in various disease states. Mechanotransduction represents cellular responses to mechanical forces, translating such factors into chemical or electrical signals which alter the activation of various cell signaling pathways. Understanding how biomechanical forces drive vascular growth in healthy and diseased tissues could create new therapeutic strategies that would either enhance or halt these processes to assist with treatments of different diseases. In the cardiovascular system, new blood vessel formation from preexisting vasculature, in a process known as angiogenesis, is driven by vascular endothelial growth factor (VEGF) binding to VEGF receptor 2 (VEGFR-2) which promotes blood vessel development. However, physical forces such as shear stress, matrix stiffness, and interstitial flow are also major drivers and effectors of angiogenesis, and new research suggests that mechanical forces may regulate VEGFR-2 phosphorylation. In fact, VEGFR-2 activation has been linked to known mechanobiological agents including ERK/MAPK, c-Src, Rho/ROCK, and YAP/TAZ. In vascular disease states, endothelial cells can be subjected to altered mechanical stimuli which affect the pathways that control angiogenesis. Both normalizing and arresting angiogenesis associated with tumor growth have been strategies for anti-cancer treatments. In the field of regenerative medicine, harnessing biomechanical regulation of angiogenesis could enhance vascularization strategies for treating a variety of cardiovascular diseases, including ischemia or permit development of novel tissue engineering scaffolds. This review will focus on the impact of VEGFR-2 mechanosignaling in endothelial cells (ECs) and its interaction with other mechanotransductive pathways, as well as presenting a discussion on the relationship between VEGFR-2 activation and biomechanical forces in the extracellular matrix (ECM) that can help treat diseases with dysfunctional vascular growth.

Supervised Cycling Training Improves Erythrocyte Rheology in Individuals With Peripheral Arterial Disease

Peripheral arterial disease (PAD) results in insufficient flow to lower extremities. Aerobic exercise provides health benefits for individuals with PAD, but basic science behind it is still debated. Twenty-one PAD patients aged about 70 years with female/male as 7/14 were recruited. Among them, 11 were randomized to have supervised cycling training (SCT) and 10 to receive general healthcare (GHC) as controls. SCT participants completed 36 sessions of SCT at the first ventilation threshold within 12 weeks and the controls received GHC for 12 weeks. Ankle-brachial index (ABI), 6-min walk test (6MWT), peak oxygen consumption (V˙O_2peak), minute ventilation (V˙_E), minute carbon dioxide production (V˙CO₂), erythrocyte rheology, including the maximal elongation index (EI_max) and shear stress at 50% of maximal elongation (SS_1/2), and the Short Form-36 (SF-36) questionnaire for quality of life (QoL) were assessed before and 12 weeks after initial visit. SCT significantly decreased the SS_1/2 as well as SS_1/2 to EI_max ratio (SS_1/2/EI_max) and increased the erythrocyte osmolality in the hypertonic region as well as the area under EI-osmolality curve. The supervised exercise-induced improvement of erythrocyte deformability could contribute to the increased peripheral tissue O₂ delivery and was possibly related with increased V˙O_2peak. The physiological benefit was associated with significantly increased ABI, 6-min walking distance, cardiorespiratory fitness, and SF-36 score. However, no significant changes in aerobic capacity and erythrocyte rheological properties were observed after 12-week of GHC. In conclusion, SCT improves aerobic capacity by enhancing erythrocyte membrane deformability and consequently promotes QoL in PAD patients.

Regular Dietary Intake of Palmitate Causes Vascular and Valvular Calcification in a Rabbit Model

Aims: Palmitic acid (PA) and oleic acid (OA) are two main dietary fatty acids. Dietary intake of PA has been associated with cardiovascular disease risk, and the effect of OA remains uncertain. Our study aimed to assess the effect of a short-term intake of lard, as source of PA and OA, on aorta and aortic valve.

Methods and Results: Rabbits were fed with two lard-enriched diets, containing either elevated levels of PA or of both PA and OA as compared to chow diet. After 16 weeks of each diet, calcification was observed in the aortic intima and in the aortic valve. The extent of calcification did not differ between the two diets. In contrast, rabbits fed chow diet did not develop any calcification. In blood, PA enrichment resulted in decreased lymphocyte and monocyte counts and increased levels of hemoglobin and haematocrit. Levels of the calcification inhibitor fetuin-A were also diminished, whereas creatinine levels were raised. Of note, none of the diets changed cholesterol levels in LDL or HDL. Comprehensive quantitative lipidomics analysis identified diet-related changes in plasma lipids. Dietary PA enrichment led to a drop of polyunsaturated fatty acids (PUFA), in particular of linoleic acid in cholesteryl esters, triglycerides and diacylglycerols (DAG). Ratios of PA to 18-carbon PUFA in DAG were positively correlated with the extent of aortic valve calcification, and inversely with monocyte counts. PA content in blood correlated with aorta calcification.

Conclusions: Regular dietary PA intake induces vascular and valvular calcification independently of traditional risk factors. Our findings raise awareness about PA-rich food consumption and its potential deleterious effect on cardiovascular health.

Association of blood viscosity with first-pass reperfusion in mechanical thrombectomy for acute ischemic stroke

BACKGROUND

Elevated blood viscosity has been reported as a risk factor for cerebrovascular disease.

OBJECTIVE

The relationship between blood viscosity and outcomes of mechanical thrombectomy (MT) for large artery occlusion (LAO) were investigated in the present study.

METHODS

A total of 238 patients were enrolled and systolic blood viscosity (SBV) and diastolic blood viscosity (DBV) were measured using the scanning capillary tube viscometer. Receiver operating characteristic (ROC) analysis was performed to specify the association of viscosity with the first-pass reperfusion (FPR). Multivariable and regression analyses were performed to evaluate the relationship of viscosity with FPR and various variables.

RESULTS

Based on ROC analysis, the best DBV cutoff value was 10.55 (cP). In multivariable analysis, high DBV was associated with FPR failure (odds ratio 2.82, 95% confidence interval 1.64-4.22; p = 0.001). Increased DVB could be associated with elevated SBV, hematocrit level, and blood urea nitrogen/creatinine ratio (p = <0.001, 0.004, and 0.002, respectively).

CONCLUSIONS

Elevated DBV was associated with FPR failure. Patients with high DBV had longer thrombus length and required more stent passages than patients with low DBV.

Effect of the Alterations in Contractility and Morphology Produced by Atrial Fibrillation on the Thrombosis Potential of the Left Atrial Appendage

Atrial fibrillation (AF) is a common arrhythmia mainly affecting the elderly population, which can lead to serious complications such as stroke, ischaemic attack and vascular dementia. These problems are caused by thrombi which mostly originate in the left atrial appendage (LAA), a small muscular sac protruding from left atrium. The abnormal heart rhythm associated with AF results in alterations in the heart muscle contractions and in some reshaping of the cardiac chambers. This study aims to verify if and how these physiological changes can establish hemodynamic conditions in the LAA promoting thrombus formation, by means of computational fluid dynamic (CFD) analyses. In particular, sinus and fibrillation contractility was replicated by applying wall velocity/motion to models based on healthy and dilated idealized shapes of the left atrium with a common LAA morphology. The models were analyzed and compared in terms of shear strain rate (SSR) and vorticity, which are hemodynamic parameters directly associated with thrombogenicity. The study clearly indicates that the alterations in contractility and morphology associated with AF pathologies play a primary role in establishing hemodynamic conditions which promote higher incidence of ischaemic events, consistently with the clinical evidence. In particular, in the analyzed models, the impairment in contractility determined a decrease in SSR of about 50%, whilst the chamber pathological dilatation contributed to a 30% reduction, indicating increased risk of clot formation. The equivalent rigid wall model was characterized by SSR values about one order of magnitude smaller than in the contractile models, and substantially different vortical behavior, suggesting that analyses based on rigid chambers, although common in the literature, are inadequate to provide realistic results on the LAA hemodynamics.

Whole blood viscosity predicts nondipping circadian pattern in essential hypertension

Aim: We aimed to investigate the association between whole blood viscosity (WBV) and nondipping pattern in patients with essential hypertension. Materials & methods: A total of consecutive 530 patients who had been evaluated by ambulatory blood pressure monitoring were included. WBV was estimated by using hematocrit and plasma total protein levels for both WBV in low shear rate (0.5 s-1) and WBV in high shear rate (208 s-1) according to the de Simone's formula. Results: In the multivariate analysis, low shear rate and high shear rate of WBV were associated independently with nondipping pattern in patients with essential hypertension. Conclusion: As a simple, inexpensive and noninvasive tool, WBV seems to be a significant predictor of nondipping hypertension.

Physiological role of plasma and its components and the clinical implications of different methods of apheresis: A narrative review

Nowadays, therapeutic plasmapheresis (TP) is accepted as part of the treatment for specific groups of diseases. The availability of different methods, including double filtration and adsorption, increases selectivity for the removal of substances. However, the use of these techniques requires a thorough understanding of the characteristics and components of plasma. By considering pivotal papers from several databases, the aim of this narrative review is to describe the characteristics of plasma related to apheresis techniques. We have tried to cover the clinical implications including physiology, estimation of plasma volume, viscosity, and a description of its components including the size, volume of distribution, and half-lives of the different substances to be removed or maintained depending on the clinical situation and applied apheresis technique. Applying this knowledge will help us to choose the right method and dosage and improve the efficacy of the procedure by preventing or addressing any complications.

Carotid artery plaque composition and distribution: near-infrared spectroscopy and intravascular ultrasound analysis

Most atherosclerotic plaques (APs) form in typical predilection areas of low endothelial shear stress (ESS). On the contrary, previous data hinted that plaques rupture in their proximal parts where accelerated blood flow causes high ESS. It was postulated that high ESS plays an important role in the latter stages of AP formation and in its destabilization. Here, we used near-infrared spectroscopy (NIRS) to analyse the distribution of lipid core based on the presumed exposure to ESS. A total of 117 carotid arteries were evaluated using NIRS and intravascular ultrasound (IVUS) prior to carotid artery stenting. The point of minimal luminal area (MLA) was determined using IVUS. A stepwise analysis of the presence of lipid core was then performed using NIRS. The lipid core presence was quantified as the lipid core burden index (LCBI) within 2 mm wide segments both proximally and distally to the MLA. The analysed vessel was then divided into three 20 mm long thirds (proximal, middle, and distal) for further analysis. The maximal value of LCBI (231.9 ± 245.7) was noted in the segment localized just 2 mm proximally to MLA. The mean LCBI in the middle third was significantly higher than both the proximal (121.4 ± 185.6 vs. 47.0 ± 96.5, P < 0.01) and distal regions (121.4 ± 185.6 vs. 32.4 ± 89.6, P < 0.01). Lipid core was more common in the proximal region when compared with the distal region (mean LCBI 47.0 ± 96.5 vs. 32.4 ± 89.6, P < 0.01).

Adaptogenic effects of Panax ginseng on modulation of cardiovascular functions

Cardiovascular diseases are a rapidly growing epidemic with high morbidity and mortality. There is an urgent need to develop nutraceutical-based therapy with minimum side effects to reduce cardiovascular risk. Panax ginseng occupies a prominent status in herbal medicine for its various therapeutic effects against inflammation, allergy, diabetes, cardiovascular diseases, and even cancer, with positive, beneficial, and restorative effects. The active components found in most P. ginseng varieties are known to include ginsenosides, polysaccharides, peptides, alkaloids, polyacetylene, and phenolic compounds, which are considered to be the main pharmacologically active constituents in ginseng. P. ginseng is an adaptogen. That is, it supports living organisms to maintain optimal homeostasis by exerting effects that counteract physiological changes caused by physical, chemical, or biological stressors. P. ginseng possesses immunomodulatory (including both immunostimulatory and immunosuppressive), neuromodulatory, and cardioprotective effects; suppresses anxiety; and balances vascular tone. P. ginseng has an antihypertensive effect that has been explained by its vasorelaxant action, and paradoxically, it is also known to increase blood pressure by vasoconstriction and help maintain cardiovascular health. Here, we discuss the potential adaptogenic effects of P. ginseng on the cardiovascular system and outline a future research perspective in this area.

The association between thrombotic and inflammatory biomarkers and lower-extremity peripheral artery disease

Lower-extremity peripheral artery disease (LEAD) is associated with increased rates of mortality and morbidity. The aim of this study was to evaluate the associations among inflammatory and thrombotic markers and lower-extremity peripheral disease. A total of 280 patients were enrolled in this study. Of these patients, 152 patients had LEAD on peripheral angiography that was performed because of suspected lower-extremity peripheral disease based on history, physical examination, and non-invasive tests. The control group consisted of 128 patients without LEAD on peripheral angiography. Patients with LEAD were classified according to trans-atlantic inter-society consensus (TASC) II classification. Subsequently, patients in TASC A to B were defined as having mild to moderate peripheral artery disease, and those in TASC C to D were defined as having advanced peripheral artery disease. Thrombotic and inflammatory markers, such as the neutrophil-to-lymphocyte ratio (NLR), the high-sensitivity C (hs-C) reactive protein level, the monocyte-to-high-density lipoprotein-cholesterol ratio, the fibrinogen to albumin ratio (FAR), and whole-blood viscosity at high shear rate (HSR) and low shear rate (LSR), were evaluated in this population. The NLR, the monocyte-to-high-density lipoprotein-cholesterol ratio, the FAR, and whole-blood viscosity, both at a LSR and a HSR, were significantly higher in patients with lower-extremity peripheral disease compared with patients without lower-extremity peripheral disease. We determined that lower-extremity peripheral disease severity was correlated with the NLR, monocyte-to-high-density lipoprotein-cholesterol ratio, FAR, whole-blood viscosity at LSR, and whole-blood viscosity at HSR (r = 0.719, P = .004; r = 0.25, P = .008; r = 0.691, P = .002; r = 0.546, P < .001; and r = 0.448, P = .001, respectively). However hs-C reactive protein levels were similar between patients with or without LEAD (2.47 ± 1.32 1.61 ± 0.91 P = .685). In addition, there was no correlation between the severity of LEAD and hs-C reactive levels. In this study, we determined that the levels of inflammatory and thrombotic biomarkers are elevated in peripheral artery disease, and these levels predict disease severity.

Radiomics from magnetic resonance imaging may be used to predict the progression of white matter hyperintensities and identify associated risk factors

OBJECTIVE

The progression of white matter hyperintensities (WMH) varies considerably in adults. In this study, we aimed to predict the progression and related risk factors of WMH based on the radiomics of whole-brain white matter (WBWM).

METHODS

A retrospective analysis was conducted on 141 patients with WMH who underwent two consecutive brain magnetic resonance (MR) imaging sessions from March 2014 to May 2018. The WBWM was segmented to extract and score the radiomics features at baseline. Follow-up images were evaluated using the modified Fazekas scale, with progression indicated by scores ≥ 1. Patients were divided into progressive (n = 65) and non-progressive (n = 76) groups. The progressive group was subdivided into any WMH (AWMH), periventricular WMH (PWMH), and deep WMH (DWMH). Independent risk factors were identified using logistic regression.

RESULTS

The area under the curve (AUC) values for the radiomics signatures of the training sets were 0.758, 0.749, and 0.775 for AWMH, PWMH, and DWMH, respectively. The AUC values of the validation set were 0.714, 0.697, and 0.717, respectively. Age and hyperlipidemia were independent predictors of progression for AWMH. Age and body mass index (BMI) were independent predictors of progression for DWMH, while hyperlipidemia was an independent predictor of progression for PWMH. After combining clinical factors and radiomics signatures, the AUC values were 0.848, 0.863, and 0.861, respectively, for the training set, and 0.824, 0.818, and 0.833, respectively, for the validation set.

CONCLUSIONS

MRI-based radiomics of WBWM, along with specific risk factors, may allow physicians to predict the progression of WMH.

KEY POINTS

• Radiomics features detected by magnetic resonance imaging may be used to predict the progression of white matter hyperintensities. • Radiomics may be used to identify risk factors associated with the progression of white matter hyperintensities. • Radiomics may serve as non-invasive biomarkers to monitor white matter status.

Intraoperative changes in whole-blood viscosity in patients undergoing robot-assisted laparoscopic prostatectomy in the steep Trendelenburg position with pneumoperitoneum: a prospective nonrandomized observational cohort study

Background

The aim of this study was to investigate the effect of the steep Trendelenburg position (STP) with pneumoperitoneum on whole-blood viscosity (WBV) in patients undergoing robot-assisted laparoscopic prostatectomy (RALP). The study also analyzed the associations of clinical patient-specific and time-dependent variables with WBV and recorded postoperative outcomes.

Methods

Fifty-eight adult male patients (ASA physical status of I or II) undergoing elective RALP were prospectively analyzed in this study. WBV was intraoperatively measured three times: at the beginning of surgery in the supine position without pneumoperitoneum; after 30 min in the STP with pneumoperitoneum; and at the end of surgery in the supine position without pneumoperitoneum. The WBV at a high shear rate (300 s^− 1) was recorded as systolic blood viscosity (SBV) and that at a low shear rate (5 s^− 1) was recorded as diastolic blood viscosity (DBV). Systolic blood hyperviscosity was defined as > 13.0 cP at 300 s^− 1 and diastolic blood hyperviscosity was defined as > 4.1 cP at 5 s^− 1.

Results

The WBV and incidences of systolic and diastolic blood hyperviscosity significantly increased from the supine position without pneumoperitoneum to the STP with pneumoperitoneum. When RALP was performed in the STP with pneumoperitoneum, 12 patients (27.3%) who had normal SBV at the beginning of surgery and 11 patients (26.8%) who had normal DBV at the beginning of surgery developed new systolic and diastolic blood hyperviscosity, respectively. The degree of increase in WBV after positioning with the STP and pneumoperitoneum was higher in the patients with hyperviscosity than in those without hyperviscosity at the beginning of surgery. Higher preoperative body mass index (BMI) and hematocrit level were associated with the development of both systolic and diastolic blood hyperviscosity in the STP with pneumoperitoneum. All patients were postoperatively discharged without fatal complications.

Conclusions

Changes in surgical position may influence WBV, and higher preoperative BMI and hematocrit level are independent factors associated with the risk of hyperviscosity during RALP in the STP with pneumoperitoneum.

Trial registration

Clinical Research Information Service, Republic of Korea, approval number: KCT0003295 on October 25, 2018.

Investigation of Blood Characteristics in Nonsyndromic Retinitis Pigmentosa: A Retrospective Study

Purpose

To investigate the characteristics of blood in nonsyndromic retinitis pigmentosa (RP) and reveal the pathogenesis of blood cells involved in blood stasis in RP.

Design

This is a retrospective observational study.

Methods

We collected vein blood from 101 cases of patients with nonsyndromic RP and 120 cases of normal individuals according to a single-blind study and used routine clinical examination to detect the indicators of blood. All the subjects were mainly from the central south of China. Data were analyzed statistically between the RP group and normal control.

Results

The indicator of platelet distribution width (PDW) in patients with RP was higher than that in the normal group; the indicators of red blood cell (RBCs), hemoglobin (HGB), hematocrit (HCT), basophils (BASs), platelets (PLTs), and plateletcrit (PCT) in the RP group were lower than those in the normal control. The differences were statistically very significant between the RP group and normal group (p < 0.01). There were no statistical differences in the other indicators between the RP and normal group.

Conclusions

The changes in RBCs and PLTs in patients with RP implied that RP induces RBC aggregation and platelet activation, leading to blood stasis which in turn initiates more apoptosis.

Radiomics nomogram based on MRI for predicting white matter hyperintensity progression in elderly adults

BACKGROUND

White matter hyperintensity (WMH) is widely observed in aging brain and is associated with various diseases. A pragmatic and handy method in the clinic to assess and follow up white matter disease is strongly in need.

PURPOSE

To develop and validate a radiomics nomogram for the prediction of WMH progression.

STUDY TYPE

Retrospective.

POPULATION

Brain images of 193 WMH patients from the Picture Archiving and Communication Systems (PACS) database in the A Medical Center (Zhejiang Provincial People's Hospital). MRI data of 127 WMH patients from the PACS database in the B Medical Center (Zhejiang Lishui People's Hospital) were included for external validation. All of the patients were at least 60 years old.

FIELD STRENGTH/SEQUENCE

T₁ -fluid attenuated inversion recovery images were acquired using a 3T scanner.

ASSESSMENT

WMH was evaluated utilizing the Fazekas scale based on MRI. WMH progression was assessed with a follow-up MRI using a visual rating scale. Three neuroradiologists, who were blinded to the clinical data, assessed the images independently. Moreover, interobserver and intraobserver reproducibility were performed for the regions of interest for segmentation and feature extraction.

STATISTICAL TESTS

A receiver operating characteristic (ROC) curve, the area under the curve (AUC) of the ROC was calculated, along with sensitivity and specificity. Also, a Hosmer-Lemeshow test was performed.

RESULTS

The AUC of radiomics signature in the primary, internal validation cohort, external validation cohort were 0.886, 0.816, and 0.787, respectively; the specificity were 71.79%, 72.22%, and 81%, respectively; the sensitivity were 92.68%, 87.94% and 78.3%, respectively. The radiomics nomogram in the primary cohort (AUC = 0.899) and the internal validation cohort (AUC = 0.84). The Hosmer-Lemeshow test showed no significant difference between the primary cohort and the internal validation cohort (P > 0.05). The AUC of the radiomics nomogram, radiomics signature, and hyperlipidemia in all patients from the primary and internal validation cohort was 0.878, 0.848, and 0.626, respectively.

DATA CONCLUSION

This multicenter study demonstrated the use of a radiomics nomogram in predicting the progression of WMH with elderly adults (an age of at least 60 years) based on conventional MRI.

LEVEL OF EVIDENCE

3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2020;51:535-546.

Ticagrelor improves blood viscosity-dependent microcirculatory flow in patients with lower extremity arterial disease: the Hema-kinesis clinical trial

Background

Microvascular blood flow (MBF) impairment in patients with lower extremity arterial disease (LEAD) is associated with more severe major adverse limb events (MALE). The contribution of ticagrelor, a P2Y12 antagonist and an adenosine enhancer, on blood viscosity (BV) and BV-dependent MBF in LEAD is unknown. The aim of the trial is to investigate the effects of ticagrelor on BV, and explore the association of BV-dependent MBF in participants with LEAD and type 2 diabetes (T2DM).

Methods

Randomized, double-blind, double-dummy, crossover trial design that compares treatment with aspirin 81 mg/ticagrelor placebo, aspirin 81 mg/ticagrelor 90 mg twice daily and aspirin placebo/ticagrelor 90 mg twice daily on high-shear (300 s⁻¹) and low-shear (5 s⁻¹) BV, and laser Doppler flowmetry (LDF) in the dorsum of the feet of participants with T2DM.

Results

We randomized 70 (45% female) participants aged (mean ± SD) 72 ± 9 years. The duration of LEAD was 12.3 ± 10.3 years, and 96.9% reported intermittent claudication symptoms. Use of statins was 93% (high-intensity 43%, moderate intensity 49%), renin–angiotensin–aldosterone system inhibitors (75%) and beta-blockers (61%). Treatment with ticagrelor with or without aspirin reduced high-shear BV by 5%, in both cases, while aspirin monotherapy increased high-shear BV by 3.4% (p < 0.0001). Ticagrelor with or without aspirin reduced low-shear BV by 14.2% and 13.9% respectively, while aspirin monotherapy increased low-shear BV by 9.3% (p < 0.0001). The combination of ticagrelor and aspirin increased MBF in the left foot compared to the other two treatments (p = 0.02), but not in the right foot (p = 0.25).

Conclusions

Ticagrelor should be considered in the treatment of microvascular disease in patients with LEAD and T2DM.

Trial registration Registration number: NCT02325466, registration date: December 25, 2014

Electronic supplementary material

The online version of this article (10.1186/s12933-019-0882-5) contains supplementary material, which is available to authorized users.

The association of estimated whole blood viscosity with hemodynamic parameters and prognosis in patients with heart failure

AIM

We aimed to investigate the association of estimated whole blood viscosity (WBV) with hemodynamic parameters and prognosis in patients with heart failure with reduced ejection fraction.

MATERIALS & METHODS

Total of 542 patients were included and followed-up for median 13 months.

RESULTS

The WBV parameters had negative relationship with right atrium pressure and positive correlation with cardiac index. The WBV parameters were found to be independent predictors of composite end point (CEP) and all-cause mortality. Every one cP increases of WBV(h) and WBV(l) were associated with 17 and 1% reductions of CEP. In Kaplan-Meier analysis, patients with low WBV quartiles were found to have significantly more CEP.

CONCLUSION

Being an easily accessible and costless prognosticator, WBV seems to be a novel marker for determining prognosis and an emerging tool to individualize heart failure with reduced ejection fraction management.

Association between Blood Viscosity and Cardiovascular Risk Factors in Patients with Arterial Hypertension in a High Altitude Setting

Background 

Blood viscosity is a determinant of vascular resistance, and it is expected to contribute to blood pressure. Arterial hypertension (HTN), in addition to other cardiovascular risk factors, contribute to cardiac morbidity. Our study aimed to establish the association between cardiovascular risk factors including HTN and whole blood viscosity in Ecuadorian patients.

Material and methods

We studied 132 patients with the diagnosis of HTN. Fifteen cardiovascular risk factors were analyzed. The association between whole blood viscosity (WBV) and the number of cardiovascular risk factors was studied. The association between blood viscosity and risk factors was analyzed.

Results 

One hundred and thirty-two patients were analyzed. Blood viscosity was associated with a number of cardiovascular risk factors. Creatinine, uric acid, total cholesterol, and low-density lipoprotein (LDL) values were significantly higher in patients with high blood viscosity.

Conclusion 

Blood viscosity is a physiological variable associated with a number of cardiovascular risk factors in hypertensive patients. Such risk factors are related to renal function and lipid profiles. In high-altitude residents, polycythemia is common, and the consequences of high hematocrit on cardiovascular morbidity in this setting deserve special attention and warrant further research.

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 ± 10.34 μg/mL, 198.85 ± 61.56 pg/mL, and 1233.32 ± 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 ± 62.5, 76.9 ± 20.6, and 33.3 ± 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.

The Contribution of Whole Blood Viscosity to the Process of Aortic Valve Sclerosis

OBJECTIVE

We aimed to investigate whether increased whole blood viscosity (WBV) could be an important factor for the occurrence of aortic valve sclerosis (AVS).

SUBJECTS AND METHODS

A total of 209 patients were enrolled in the study. WBV was calculated using the hematocrit and total plasma protein at a low shear rate (LSR) and a high shear rate (HSR). AVS was defined as irregular valve thickening and calcification (without evidence of outflow obstruction) documented by a peak transvalvular velocity < 2.5 m/s on echocardiographic examination. The patient group consisted of 109 patients with AVS (77 females, 32 males), and 100 subjects without AVS (65 females, 35 males) were assigned to the control group.

RESULTS

In the AVS group, WBV values were significantly higher for HSR (17.4 ± 0.5 vs. 17.1 ± 0.7 208 s-1, p < 0.001) and LSR (65.9 ± 12.5 vs. 59.7 ± 16.7 0.5 s-1, p = 0.002). In multivariate logistic regression analysis, WBV at HSR and LSR were independent predictors of AVS (odds ratio, OR: 2.24, 95% confidence interval, CI: 1.38-3.64, p = 0.001; OR: 1.026, 95% CI: 1.006-1.046, p = 0.01, respectively). Receiver-operating characteristic (ROC) curve analysis indicated that a WBV cutoff value of 65.4 at LSR had a sensitivity of 46.8% and a specificity of 60.0% (area under the ROC curve, AUC: 0.615, 95% CI: 0.535-0.696, p = 0.004), and a WBV cutoff value of 17.1 at HSR had a sensitivity of 61.5% and specificity of 53% (AUC: 0.648, 95% CI: 0.571-0.725, p < 0.001) for the prediction of AVS.

CONCLUSION

This study demonstrated that WBV was independently associated with AVS. WBV could be an indicator of inflammation and vessel remodeling without evidence of outflow obstruction.

Elevated blood viscosity is associated with cerebral small vessel disease in patients with acute ischemic stroke

BACKGROUND

Increased level of blood viscosity, which is one of the major factors that determine blood rheology, has been reported as a risk factor or predictor for cerebrovascular events. We investigated how blood viscosity is associated with acute stroke and chronic radiological manifestations of cerebral small vessel disease, and how blood viscosity changes after stroke.

METHODS

We prospectively enrolled consecutive patients with acute ischemic stroke. Whole blood viscosities at a low or high shear rate were measured using a scanning capillary tube viscometer, and were referred to as diastolic blood viscosity (DBV) and systolic blood viscosity (SBV), respectively. Correlations between blood viscosity and acute stroke etiology or chronic radiological manifestations of cerebral small vessel disease were investigated. The temporal profiles of blood viscosity at the onset of stroke and follow-up at 1 and 5 weeks were investigated.

RESULTS

Of the 127 patients admitted with acute ischemic stroke, 63 patients were included in the final analyses. DBV at the onset of stroke was significantly higher in small artery occlusion (SAO) stroke than in other stroke subtypes (p = 0.037). DBV showed a significant positive correlation with the number of chronic lacunes (r = 0.274, p = 0.030). The temporal profiles of DBV in SAO stroke showed a transient decrease due to the hydration therapy after 1 week and recurrent elevation at 5 week follow-up (p = 0.009).

CONCLUSIONS

Our study suggests that elevated DBV may play a role in the development of acute and chronic manifestations of cerebral small vessel disease. The recurring elevation of DBV in SAO stroke indicates that sufficient hydration and additional therapeutic interventions targeting blood viscosity may be needed in patients with SAO stroke.

Physical Properties of Blood Are Altered in Young and Lean Women with Polycystic Ovary Syndrome

Classic features of polycystic ovary syndrome (PCOS) include derangement of metabolic and cardiovascular health, and vascular dysfunction is commonly reported. These comorbidities indicate impaired blood flow; however, other than limited reports of increased plasma viscosity, surprisingly little is known regarding the physical properties of blood in PCOS. We aimed to investigate whether haemorheology was impaired in women with PCOS. We thus measured a comprehensive haemorheological profile, in a case-control design, of lean women with PCOS and age-matched healthy controls. A clinical examination determined similar cardiovascular risk for the two groups. Whole blood and plasma viscosity was measured using a cone-plate viscometer. The magnitude and rate of red blood cell (RBC) aggregation was determined using a light-transmission aggregometer, and the degree of RBC deformability was measured via laser-diffraction ektacytometry. Plasma viscosity was significantly increased in women with PCOS. Blood viscosity was also increased for PCOS at lower-to-moderate shear rates in both native and standardised haematocrit samples. The magnitude of RBC aggregation–a primary determinant of low-shear blood viscosity–was significantly increased in PCOS at native and 0.4 L·L^-1 haematocrit. No difference was detected between PCOS and CON groups for RBC deformability measurements. A novel measure indicating the effectiveness of oxygen transport by RBC (i.e., the haematocrit-to-viscosity ratio; HVR) was decreased at all shear rates in women with PCOS. In a group of young and lean women with PCOS with an unremarkable cardiovascular risk profile based on clinical data, significant haemorheological impairment was observed. The degree of haemorheological derangement observed in the present study reflects that of overt chronic disease, and provides an avenue for future therapeutic intervention in PCOS.

Effects of Shenlian extract on experimental atherosclerosis in ApoE-deficient mice based on ultrasound biomicroscopy

Background

This study directly and dynamically investigated the effects of SL extract (i.e., a combination of Radix Salviae miltiorrhizae and Andrographis paniculata extract) on plaque progression in vivo by high resolution ultrasound biomicroscopy (UBM).

Methods

An atherosclerosis model was established by placing a perivascular collar on the right common carotid artery in apolipoprotein E-deficient (ApoE^-/-) mice. Thickness, plaque area and local blood flow were observed by UBM, pathological changes were observed by histochemical staining, and lipid levels were measured by respective commercially available kits.

Results

Compared with the model group, the SL extract groups showed reduced wall thickness of the aortic arch (GC: P = 0.001, P = 0.002, and P < 0.001; LC: P < 0.001, P < 0.001, and P < 0.001; BC: P = 0.027, P = 0.017, and P = 0.003; respectively), which presented with retarded plaque progression of the cartoid artery with concordantly increased blood flow (P = 0.002 and P < 0.001) as visualized in vivo by UBM. Histological analysis confirmed the reduction of carotid atherosclerosis.

Conclusions

The SL extract inhibited the formation of atherosclerotic plaques in an ApoE^-/- mice model by UBM analysis, and did so by effects that ameliorated local blood flow and improved blood lipid levels.

The Association between Whole Blood Viscosity and Coronary Collateral Circulation in Patients with Chronic Total Occlusion

Background and Objectives

Coronary collateral circulation (CCC) has been attributed as inborn bypass mechanisms supporting ischemic myocardium. Various factors have been postulated in CCC. Whole blood viscosity (WBV) has been an underappreciated entity despite close relationships between multiple cardiovascular diseases. WBV can be calculated with a validated equation from hematocrit and total plasma protein levels for a low and high shear rate. On the grounds, we aimed to evaluate the association between WBV and CCC in patients with chronic total occlusion.

Subjects and Methods

A total of 371 patients diagnosed as having at least one major, chronic total occluded coronary artery were included. 197 patients with good CCC (Rentrop 2 and 3) composed the patient group. The poor collateral group consisted of 174 patients (Rentrop grade 0 and 1).

Results

Patients with poor CCC had higher WBV values for a low-shear rate (LSR) (69.5±8.7 vs. 60.1±9.8, p<0.001) and high-shear rate (HSR) (17.0±2.0 vs. 16.4±1.8, p<0.001) than the good collateral group. Correlation analysis demonstrated a significant negative correlation between the grade of CCC and WBV for LSR (β=0.597, p<0.001) and HSR (β=0.494, p<0.001). WBV for LSR (β=0.476, p<0.001) and HSR (β=0.407, p<0.001) had a significant correlation with the synergy between percutaneous coronary intervention with taxus and cardiac surgery (SYNTAX) score. A multivariate analysis showed that the WBV for both shear rates were independent risk factors of poor CCC (WBV at LSR, OR: 1.362 CI 95%: 1.095-1.741 p<0.001 and WBV at HSR, 1.251 CI 95%: 1.180-1.347 p<0.001).

Conclusion

WBV has been demonstrated as the overlooked predictor of poor coronary collateralization. WBV seemed to be associated with microvascular perfusion and angiogenesis process impairing CCC development.

Determinants of resting cerebral blood flow in sickle cell disease

Stroke is common in children with sickle cell disease and results from an imbalance in oxygen supply and demand. Cerebral blood flow (CBF) is increased in patients with sickle cell disease to compensate for their anemia, but adequacy of their oxygen delivery has not been systematically demonstrated. This study examined the physiological determinants of CBF in 37 patients with sickle cell disease, 38 ethnicity matched control subjects and 16 patients with anemia of non-sickle origin. Cerebral blood flow was measured using phase contrast MRI of the carotid and vertebral arteries. CBF increased inversely to oxygen content (r(2)  = 0.69, P < 0.0001). Brain oxygen delivery, the product of CBF and oxygen content, was normal in all groups. Brain composition, specifically the relative amounts of grey and white matter, was the next strongest CBF predictor, presumably by influencing cerebral metabolic rate. Grey matter/white matter ratio and CBF declined monotonically until the age of 25 in all subjects, consistent with known maturational changes in brain composition. Further CBF reductions were observed with age in subjects older than 35 years of age, likely reflecting microvascular aging. On multivariate regression, CBF was independent of disease state, hemoglobin S, hemoglobin F, reticulocyte count and cell free hemoglobin, suggesting that it is regulated similarly in patients and control subjects. In conclusion, sickle cell disease patients had sufficient oxygen delivery at rest, but accomplish this only by marked increases in their resting CBF, potentially limiting their ability to further augment flow in response to stress. Am. J. Hematol. 91:912-917, 2016. © 2016 Wiley Periodicals, Inc.

Increased Blood Viscosity in Ischemic Stroke Patients with Small Artery Occlusion Measured by an Electromagnetic Spinning Sphere Viscometer

BACKGROUND AND PURPOSE

High blood viscosity causes blood stagnation and subsequent pathological thrombotic events, resulting in the development of ischemic stroke. We hypothesize that the contribution of blood viscosity may differ among ischemic stroke subtypes based on specific pathological conditions. We tried to verify this hypothesis by measuring blood viscosity in acute ischemic stroke patients using a newly developed electromagnetic spinning sphere (EMS) viscometer.

METHODS

Measurements in acute ischemic stroke patients were performed 4 times during admission and data were compared with those obtained from 100 healthy outpatient volunteers.

RESULTS

We enrolled 92 patients (cardioembolism: 25, large artery atherosclerosis: 42, and small artery occlusion [SAO]: 25) in this study. Comparisons of blood viscosity between the ischemic stroke subgroups and control group revealed that blood viscosity at the date of admission was significantly higher in the SAO group (5.37 ± 1.11 mPa⋅s) than in the control group (4.66 ± .72 mPa⋅s) (P < .01). Among all subtype groups showing a reduction in blood viscosity after 2 weeks, the SAO group showed the highest and most significant reduction, indicating that SAO patients had the most concentrated blood at the onset.

CONCLUSIONS

Blood viscosity was significantly increased in the SAO group at the date of admission, which indicated the contribution of dehydration to the onset of ischemic stroke. The importance of dehydration needs to be emphasized more in the pathogenesis of SAO. The clinical application of the EMS viscometer is promising for understanding and differentiating the pathogenesis of ischemic stroke.