Relation of blood viscosity to demographic and physiologic variables and to cardiovascular risk factors in apparently normal adults

A gray zone: Role of transesophageal echocardiography before atrial tachycardia catheter ablation

INTRODUCTION

There is a lack of studies in the literature directly investigating the relationship between atrial tachycardia (AT) and left atrial (LA)/left atrial appendage (LAA) thrombus, and current guidelines do not provide strong recommendations regarding the use of transesophageal echocardiography (TEE) before AT catheter ablation. This study aims to elucidate the relationship between AT and the presence of LA/LAA thrombus and contribute to the literature on the use of TEE before AT catheter ablation.

METHODS

This single-center retrospective observational study screened patients who underwent TEE between February 10, 2019, and February 10, 2023. Patients were assigned to the AT patient and control groups. TEE was conducted to exclude thrombus in the AT ablation group. The control group included patients who underwent TEE for interatrial septum evaluation and had LA imaging during TEE but did not have atrial arrhythmia. To mitigate bias between the AT patient group and the control group, they were randomized 1:1 using propensity-score matching (PSM). Following randomization, each group consisted of 49 patients.

RESULTS

All analyses were conducted after PSM. There were no statistically significant differences between the AT patient and control groups in terms of baseline clinical characteristics and echocardiographic features. Additionally, no significant differences were found between the blood viscosities calculated at low and high shear rates in both groups. The study revealed a significant difference between the two groups in the presence of LA spontaneous echo contrast (SEC) (24.5% in AT group vs 0% in Control group, p = .001), but not in the presence of thrombi (8.2% in AT group vs 0% in Control group, p = .117).

CONCLUSION

Compared to the control group, the presence of SEC was significantly higher in the AT patient group. The increased frequency of SEC in AT patients suggests the hypothesis that AT may contribute to LA stasis. The routine use of TEE before AT catheter ablation remains controversial, despite the presence of LA thrombus and SEC in the AT patient group. The clinical assessment of thrombus presence before the procedure must be conducted on a patient-specific basis.

Calculated whole blood viscosity in non-diabetic subjects with asymptomatic carotid atherosclerosis: How insulin resistance may affect blood viscosity

BACKGROUND AND OBJECTIVE

Asymptomatic atherosclerosis is an important early marker of vascular damage and, among its risk factors, hemorheological alterations play an important role.

PATIENTS AND METHODS

In a cohort of 85 non-diabetic subjects with asymptomatic carotid atherosclerosis (ACA), we have measured whole blood viscosity (cWBV) according to the haematocrit and plasma fibrinogen level. The cWBV distinguish the subgroup of ACA subjects with 3-5 cardiovascular risk factors (CRFs) from that with 1-2 CRFs and the same behavior is present for haematocrit and plasma fibrinogen level. Therefore, we divided the whole group of ACA subjects according to the medians of the four surrogate indexes with an insulin resistance degree of TG/HDL-C, TyG, VAI and LAP.

RESULTS

The analysis of the correlation between cWBV and each index of insulin resistance has shown that no correlation is present in the whole group and in the group of ACA subjects with 1-2 CRFs, while in the subgroup with 3-5 CRFs there is a positive correlation between cWBV with TG/HDL-C and TyG at a low degree of statistical significance.

CONCLUSIONS

The date underline that subjects with this clinical condition have an unaltered evaluation of the cWBV compared to the other indices.

Hematocrit Predicts Poor Prognosis in Patients with Acute Ischemic Stroke or Transient Ischemic Attack

This study aims to investigate the association between HCT (Hematocrit) levels and adverse outcomes in patients with acute ischemic stroke (AIS) or transient ischemic attack (TIA); 14,832 participants from the China National Stroke Registry-III with AIS or TIA were analyzed. Participants were categorized into quartiles based on baseline HCT levels. The primary outcome was poor functional outcomes (modified Rankin Scale ≥ 3) during three months, with secondary outcomes including all-cause death, stroke recurrence, and combined vascular events. Logistic regression or Cox regression models were used to assess the relationship between HCT and clinical outcomes. Compared to the third quartile, patients in the lowest quartile group showed increased risk of poor functional outcome (adjusted OR: 1.35, 95% CI: 1.15-1.58, p < 0.001), patients in the lowest quartile had a higher risk of all-cause death (adjusted HR: 1.68, 95% CI: 1.06-2.68, p = 0.028), as did those in the highest quartile (adjusted HR: 2.02, 95% CI: 1.26-3.25, p = 0.004). Sensitivity analysis shows that the association of HCT with all-cause death weakened, while the association with poor functional outcome was strengthened after excluding patients with recurrent stroke. Our results indicated that HCT level could be used as a short-term predictor for poor functional outcomes and all-cause death in patients with AIS or TIA.

Mendelian randomization study of whole blood viscosity and cardiovascular diseases

AIMS

Association between whole blood viscosity (WBV) and an increased risk of cardiovascular disease (CVD) has been reported. However, the causal relationship between WBV and CVD remains not thoroughly investigated. The aim of this study was to investigate the causal relation between WBV and CVD.

METHODS

Two-sample Mendelian randomization (MR) was employed, with inverse variance weighting (IVW) as the primary method, to investigate the casual relationship between WBV and CVD. The calculated WBV and medical records of 378,210 individuals participating in the UK Biobank study were divided into halves and analyzed.

RESULTS

The means of calculated WBVs were 16.9 (standard deviation: 0.8) and 55.1 (standard deviation: 17.2) for high shear rate (HSR) and low shear rate (LSR), respectively. 37,859 (10.0%) major cardiovascular events (MACE) consisted of 23,894 (6.3%) cases of myocardial infarction (MI), 9,245 (2.4%) cases of ischemic stroke, 10,377 (2.7%) cases of revascularization, and 5,703 (1.5%) cases of coronary heart disease-related death. In the MR analysis, no evidence was found indicating a causal effect of WBV on MACE (IVW p-value for HSR = 0.81, IVW p-value for LSR = 0.47), MI (0.92, 0.83), ischemic stroke (0.52, 0.74), revascularization (0.71, 0.54), and coronary heart disease-related death (0.83, 0.70). The lack of sufficient evidence for causality persisted in other MR methods, including weighted median and MR-egger.

CONCLUSIONS

The Mendelian randomization analysis conducted in this study does not support a causal relationship between calculated WBV and CVD.

Digital gangrene in systemic sclerosis patients: not only due to the microvascular disease

OBJECTIVE

This study aims to investigate the characteristics, risk factors, and outcomes of digital gangrenes in SSc patients, and to identify whether vasculitis is one of the causes for digital gangrene.

METHODS

A retrospective case-control study was performed from February 2003 to April 2021. Forty-three SSc patients with digital gangrene admitted to Peking Union Medical College Hospital were included. One-hundred forty-six age- and sex-matched SSc patients without gangrene were selected as controls during the same period. Univariate and multivariate logistic regression analysis was used to determine risk factors.

RESULTS

Among 43 SSc patients with gangrene, 93.0% had Raynaud's phenomenon (RP) and 32.6% had current or previous digital ulcers (DU). SSc patients with digital gangrene had more ESR elevation (54.8% vs. 34.9%, p = 0.020) and higher level of high-sensitive C reactive protein (median 7.2 mg/L vs. 1.8 mg/L, p = 0.045) compared with controls. In the multivariable logistic regression analysis, smoking history (OR 4.119, p = 0.037), anti-centromere antibody positivity (OR 3.542, p = 0.016), anti-neutrophil cytoplasmic antibody positivity (OR 22.605, p = 0.037), and anti-phospholipid antibody positivity (OR 16.563, p = 0.001), as well as elevated ESR (OR 2.524, p = 0.038) were identified as independent risk factors for gangrenes. Most (79.1%) cases were treated with combination of immunosuppressive and vasodilating therapy, and four cases also got remised after treatment of only glucocorticoid and immunosuppressive agent.

CONCLUSION

Smoking history; positive-ACA, ANCA, and anti-phospholipid antibodies; and increased ESR were independent risk factors for digital gangrenes in SSc. Vasculitis and macrovascular disease may contribute to the progression of digital gangrenes. Key Points •18.6% of SSc patients with digital gangrene had macrovascular stenosis. •Smoking, positive-ACA, ANCA, aPL, and increased ESR were indicators for digital gangrenes in SSc. •Vasculitis and macrovascular disease may involve in the pathogenesis.

Whole blood viscosity is associated with reduced myocardial mechano-energetic efficiency in nondiabetic individuals

INTRODUCTION

This cross-sectional study aimed to investigate the association between myocardial mechano-energetic efficiency (MEE) and whole blood viscosity (WBV) in nondiabetic adults participating in the CATAnzaro MEtabolic RIsk factors (CATAMERI) study.

METHODS

1143 participants underwent an oral glucose tolerance test and an echocardiogram for myocardial MEE per gram of left ventricular mass (MEEi) measurement. WBV was measured as: [0.12 × h] + [0.17 × (p-2.07)], where h is haematocrit and p is plasma protein levels.

RESULTS

Study population includes 595 males and 548 females with a mean age of 46 ± 12 years and a mean BMI of 30.0 ± 6.2 kg/m2 . Individuals with normal glucose tolerance were 63%, while those with impaired fasting glucose, impaired glucose tolerance and or the combination of both were 14.3%, 13% and 9.7%, respectively. A univariate analysis showed that MEEi was significantly associated with sex, age, smoking, BMI, waist circumference, total cholesterol, HDL, triglycerides, fasting glucose, fasting insulin, HOMA-IR index, glucose tolerance, C-reactive protein, haematocrit, haemoglobin, plasma protein and WBV. In a multivariable regression model including variables that were significantly associated with MEEi in univariate analysis, MEEi was associated with HOMA-IR (β = -0.144, p < .001), age (β = -0.140, p < .001), WBV (β = -0.129, p < .001) and glucose tolerance (β = -0.064, p = .04). The independent association between WBV and MEEi remained statistically significant (β = -0.122, p < .001) when antihypertensive therapy and lipid-lowering therapy were included in the model.

CONCLUSION

WBV is associated with decreased myocardial MEE independently of other cardiovascular risk factors.

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.

Investigation of hemorheological parameters in patients with major depressive disorder

BACKGROUND

Hemorheological parameters have been reported to be altered in cardiovascular disease. Major depression has been associated with increased risk of cardiovascular disease.

OBJECTIVE

Our hypothesis is that hemorheological parameters are disturbed in major depressive disorder.

METHODS

Major depressive disorder and control groups consisted of 50 subjects. Plasma viscosity, erythrocyte aggregation, erythrocyte deformability, hematological parameters and hematological parameters were examined.

RESULTS

Plasma viscosity was statistically significantly higher, erythrocyte elongation index at 0.53 Pa and 0.95 Pa was lower, and MCV, MCH, and MCHC values were also lower in the major depression group (P < 0.05). Elongation index and plasma viscosity were correlated with depressive symptomatology.

CONCLUSIONS

The increased plasma viscosity and decreased elongation index of erythrocytes indicate an unfavorable hemorheological situation in patients with major depressive disorder compared with healthy controls. The results of this study confirm the findings of studies finding a potential threat to cardiovascular health from major depressive disorder. Increased plasma viscosity and decreased erythrocyte elongation index in depressed patients may be risk factors for cardiovascular events and provide data on the causality of the association between depression and cardiovascular disease.

Association between hemoglobin concentration and hypertension risk in native Tibetans at high altitude

Previous studies examining the association between hemoglobin concentration and hypertension have yielded inconsistent results. There is still a lack of evidence regarding the association between hemoglobin concentration and hypertension risk in native Tibetans at high altitude. We performed this cross-sectional study in Luhuo County of Ganzi Tibetan Autonomous Prefecture (average altitude of 3500 m). In this study, we enrolled 1547 native Tibetans. The association between hemoglobin concentration and hypertension risk was examined by multivariate binary logistic regression and smooth curve fitting. Native Tibetans with hypertension had significantly higher hemoglobin concentrations than those without hypertension (165.9 ± 21.5 g/L vs. 157.7 ± 19.2 g/L, P < 0.001). An increase in hemoglobin concentration of 1 g/L was associated with hypertension (odds ratio [OR] 1.02, 95% confidence interval [CI] 1.01-1.02) after confounder adjustment. The highest hemoglobin concentration group (exceeding 173 g/L) was associated with an increased hypertension risk compared with the bottom quartile of hemoglobin concentration (OR 2.39, 95% CI 1.48-3.85). Hemoglobin concentration (per 1 g/L change) exceeding 176 g/L was significantly associated with an increased hypertension risk (OR 1.04, 95% CI 1.03-1.06). Additionally, high-altitude polycythemia significantly increased the hypertension risk compared with a normal hemoglobin concentration (OR 2.92, 95% CI 1.25-6.86). A similar result was observed for mild polycythemia (OR 1.74, 95% CI 1.29-2.34). In conclusion, hemoglobin concentration was associated with hypertension risk in native Tibetans. When the hemoglobin concentration exceeded a certain value (approximately 176 g/L), the risk of hypertension was significantly increased.

Thrombotic Risk and Calculated Whole Blood Viscosity in a Cohort of Patients With New Diagnosis of Multiple Myeloma

The pathogenesis of venous thromboembolism in multiple myeloma is still poorly understood because multiple factors are involved. In particular, the increase in whole blood viscosity has a key role and, therefore, we performed an evaluation of some hemorheological determinants in multiple myeloma patients, putting them in relation to the thrombotic risk, with the aim to evaluate if an alteration of the hemorheological pattern was associated with a higher thrombotic risk. We performed an observational retrospective cohort study with data collected from January 2017 to September 2022. In a group of 190 patients with newly diagnosed multiple myeloma, we have examined the trend of calculated blood viscosity according to the Merrill formula, and we stratified the patients for the thrombotic risk in accordance with the IMWG/NCCN guidelines and with IMPEDE VTE score. Using the thrombotic risk stratification proposed by IMWG/NCCN any variation in calculated blood viscosity is evident, while, with the IMPEDE VTE score, we observed an increase in calculated blood viscosity in patients with "intermediate + high" risk. The calculated blood viscosity is higher in subjects presenting an "intermediate + high" thrombotic risk according to the IMPEDE VTE score. This association could therefore lay the groundwork for further research with the aim to confirm the role of hemorheological pattern in MM-related thrombotic risk.

A Predictive Model for Cancer-Associated Thrombosis in Japanese Cancer Patients: Findings from the J-Khorana Registry

Background  Although the close relationship between cancer and venous thromboembolism (VTE) has been identified, risk stratification for VTE in Japanese patients with cancer remains unclear. Objectives  This study aimed to validate the Khorana VTE risk assessment score (KRS) for VTE diagnosis and establish an optimal predictive model for VTE in Japanese patients with cancer. Methods  A total of 7,955 Japanese patients with cancer were subdivided into low- (0), intermediate- (1-2), and high-score (3) groups according to the KRS. Using 37 explanatory variables, a total of 2,833 patients with cancer were divided into derivation and validation cohorts (5:5). A risk model for Japanese participants was developed using the derivation cohort data. Results  The prevalence of VTE in low-, intermediate-, and high-score patients was 1.2, 2.5, and 4.3%, respectively. Logistic regression analysis demonstrated that cancer stage (III-IV) and KRS ≥ 2 were independent and significant predictors of VTE onset. The risk model for VTE assigned 1 point to body mass index ≥25 kg/m 2 and 2 points each to the prevalence of osteochondral cancer and D-dimer level ≥1.47 µg/mL. The areas under the curve of the risk model were 0.763 and 0.656 in the derivation and validation cohorts, respectively. Conclusion  The KRS was useful in Japanese patients, and our new predictive model may be helpful for the diagnosis of VTE in Japanese patients with cancer.

Equivalence in Color-coded Duplex Sonography Parameters before Complex Microsurgery

Background

Color-coded duplex sonography (CCDS) is a widely proposed noninvasive diagnostic tool in microsurgery. CCDS has been applied to lower extremity salvage cases to define appropriate blood flow velocity criteria for achieving arterial success in diabetic foot and complex microsurgery cases. This study aimed to compare the success ratio of free flaps when using CCDS versus cases where CCDS was not used.

Methods

We included complex microsurgery cases from 2019 to 2021. These cases were subsequently categorized into two groups: group A consisted of cases where CCDS parameters were applied, whereas group B comprised cases where CCDS was not performed at all.

Results

The study encompassed 14 cases (11 men and three women). The age range varied from 23 to 62 years, with an average age of 42. Using CCDS analysis and planning demonstrated improved outcomes in comparison with cases where CCDS was not performed, albeit without statistical significance (P = 0.064).

Conclusions

The application of CCDS proves to be beneficial in the realm of microsurgery. Although not achieving statistical significance, our data imply that CCDS utilization holds promise for enhancing microsurgical procedures.

Viscosity-responsive NIR-II fluorescent probe with aggregation-induced emission features for early diagnosis of liver injury

As the primary organ for drug metabolism and detoxification, the liver is susceptible to damage and seriously impaired function. In situ diagnosing and real-time monitoring of liver damage are thus of great significance but remain limited owing to the lack of reliable in vivo visualization protocols with minimal invasion. Herein, we reported for the first time an aggregation-induced emission (AIE) probe, namely DPXBI, emitting light in the second near-infrared window (NIR-II) for early diagnosis liver injury. DPXBI featured by strong intramolecular rotations, excellent aqueous solubility and robust chemical stability, is powerfully sensitive to viscosity alteration affording rapid response and high selectivity, through NIR-Ⅱ fluorescence intensity changes. The prominent viscosity-responsive performance enables DPXBI to accurately monitor both drug-induced liver injury (DILI) and hepatic ischemia-reperfusion injury (HIRI) with excellent image contrast to the background. By using the presented strategy, the detection of liver injury in mouse model can be achieved at least several hours earlier than typical clinical assays. Moreover, DPXBI is able to dynamically track the liver improvement process in vivo in the case of DILI when the hepatotoxicity is alleviated by using hepatoprotective medication. All these results demonstrate that DPXBI is a promising probe for investigating viscosity-associated pathological and physiological processes.

The Relationship Between Nitrate-Induced Headache and -Blood Viscosity: An Observational Prospective Study

ABSTRACT

Nitrates are one of the most prescribed medications in the treatment of angina pectoris today. Headache is the most common side effect of nitrates, and there is limited prospective data on the determinants of this effect. Our aim in this study is to open a foresight window for clinicians in clinical practice by explaining the possible relationship between nitrate-induced headache and whole-blood viscosity (WBV). After coronary revascularization treatment, 869 patients with angina who were prescribed nitrate preparations were divided into groups according to the development of headache or not and categorized according to the 4-grade scale level. Those who had no headache during nitrate use were graded as grade 0, those who felt mild headache were grade 1, those who felt moderate headache were grade 2, and those who described severe headache were graded as grade 3. The groups were compared according to WBV values. A total of 869 participants were included in the study. Most patients (82.1%) experienced some level of headache. Headache severity correlated with both WBV at high shear rate (r = 0.657; P < 0.001) and WBV at low shear rate (r = 0.687; P < 0.001). In multivariate analysis, WBV was determined as an independent predictor of headache experience. WBV predicted nitrate-induced headache with 75% sensitivity and 75% specificity at high shear rate and 77% sensitivity and 77% specificity at low shear rate. WBV seems to be one of the major determinants for nitrate-induced headache. WBV may be a guide for initiating alternative antianginal drugs without prescribing nitrates to the patient to increase patient compliance.

Calculated Whole Blood Viscosity and Albumin/Fibrinogen Ratio in Patients with a New Diagnosis of Multiple Myeloma: Relationships with Some Prognostic Predictors

BACKGROUND

In this single center study, we retrospectively evaluated the calculated hemorheological profile in patients with a new diagnosis of multiple myeloma, with the aim to evaluate possible relationships with some prognostic predictors, such as ISS, albumin levels, beta2-microglobulin, red cell distribution width, and bone marrow plasma cell infiltration.

METHODS

In a cohort of 190 patients, we examined the calculated blood viscosity using the de Simone formula, and the albumin/fibrinogen ratio as a surrogate of erythrocyte aggregation, and then we related these parameters to prognostic factors, using the Kruskal-Wallis and the Mann-Whitney tests, respectively.

RESULTS

From our analysis, it emerged that the evaluated hemorheological pattern differed in the three isotypes of multiple myeloma, and the whole blood viscosity was higher in IgA and IgG isotypes with respect to the light chain multiple myeloma (p < 0.001). Moreover, we observed that, as the ISS stage progressed, the albumin/fibrinogen ratio was reduced, and the same hemorheological trend was traced in subgroups with lower albumin levels, higher beta2-microglobulin and red cell distribution width RDW values, and in the presence of a greater bone marrow plasma cell infiltrate.

CONCLUSIONS

Through the changes in blood viscosity in relation to different prognostic factors, this analysis might underline the role of the hemorheological pattern in multiple myeloma.

Components of the Complete Blood Count as a Risk Predictor for Incident Hypertension in a Large Taiwanese Population Follow-up Study

BACKGROUND

Previous studies investigating the relationship between hypertension (HT) and hematological parameters report inconsistent results, and most them included a small number of participants or only conducted a cross-sectional analysis of 1 or 2 hematological factors. Moreover, no large cohort follow-up studies have investigated this topic. The aim of this longitudinal study was to explore associations between components of the complete blood count (CBC) and incident HT using data from a large Taiwanese biobankMethods and Results: Hematological parameters including white blood cell (WBC) count, red blood cell (RBC) count, hemoglobin, hematocrit (HCT), and platelet count were evaluated. We included 21,293 participants who did not have HT at baseline and followed them for a mean period of 3.9 years. During follow-up, 3,002 participants with new-onset HT (defined as incident HT) were identified. Univariable analysis revealed that high WBC count, high RBC count, high hemoglobin, high HCT, and low platelet count were associated with incident HT. Multivariable analysis after adjusting potential confounding factors found high WBC count (odds ratio [OR], 1.057; 95% confidence interval [CI], 1.028 to 1.087; P<0.001) and high HCT (OR, 1.023; 95% CI, 1.010 to 1.036; P<0.001) were still significantly associated with incident HT.

CONCLUSIONS

High WBC count and high HCT were associated with incident HT.

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.

Increased whole blood viscosity is associated with primary idiopathic complete atrioventricular block and poor clinical outcomes in these patients

BACKGROUND

Complete atrioventricular block is most commonly caused by age-related degeneration and fibrosis in the cardiac conduction system and is called primary idiopathic complete atrioventricular (iCAVB). Although many factors affect this situation, which increases with age in the cardiac conduction system, the relationship between whole blood viscosity (WBV) and iCAVB has not been clarified until now. In this study, we aim to reveal the relationship between iCAVB and WBV.

METHODS AND RESULTS

141 patients with dual-chamber permanent pacemaker implanted for iCAVB and 140 age- and sex-matched subjects were included in this study. The WBV values of the study groups were compared in both high shear rate (HSR) and low shear rate (LSR). Both WBV at HSR and WBV at LSR were significantly higher in the iCAVB group compared to the control group (16.11 [15.14-16.89] vs 14.40 [13.62-15.58]; 39.82 [17.43-55.23] vs 1.38 [-13.14-26.73]; p < 0.001, respectively). The patient population was followed up for an median of 38 months for all-cause mortality. Higher mortality rates were found in higher WBV at HSR and WBV at LSR (p < 0.001,for both).

CONCLUSIONS

In this study, WBV was found to be an independent predictor for iCAVB, and in these patients WBV was associated with poor clinical outcomes.

In Vivo Suction Pressures of Venous Cannulas During Veno-venous Extracorporeal Membrane Oxygenation

Extracorporeal lung support includes the risk of hemolysis due to suction pressures. Manufacturers measure the negative suction pressure across drainage cannulas for their products in vitro using water. Clinical experience suggests that hemolysis occurs in vivo already at much lower flow rates. The aim of this study was to analyze the in vivo suction pressure for veno-venous extracorporeal membrane oxygenation (VV-ECMO) cannulas. Prospective, observational study at a tertiary-care intensive care unit: 15 patients on VV-ECMO for severe ARDS were prospectively included. In vitro , the 25 Fr drainage cannula pressure drops below a critical level of around -100 mm Hg at a flow rate of 7.9 L/min, the 23 Fr drainage cannula at 6.6 L/min. In the clinical setting, critical suction pressures were reached at much lower flow rates (5.5 and 4.7 L/min; p < 0.0001, nonlinear regression). The in vitro data largely overestimate the safely achievable flow rates in daily clinical practice by 2.4 L/min (or 44%, 25 Fr) and 1.9 L/min (or 41%, 23 Fr). In vivo measurement of suction pressure of venous drainage cannulas differed significantly from in vitro derived measurements as the latter largely underestimate the resulting suction pressure.

Another possible determinant for ischemic stroke with nonvalvular atrial fibrillation other than conventional oral anticoagulant treatment: The relationship between whole blood viscosity and stroke☆

OBJECTIVES

Patients with nonvalvular atrial fibrillation (NVAF) still experience ischemic stroke despite recommended medications and this could be the consequence of increased whole blood viscosity (WBV). We evaluated the predictive value of WBV for stroke in patients with NVFA despite receiving oral anticoagulant (OAC) therapy.

METHODS

One thousand and forty-three NVAF patients on OAC medication were followed up for median 36.13 ± 18.31 months. WBV was calculated according to the validated de Simone's formula.

RESULTS

WBV was significantly higher in stroke group when compared to non-stroke group at both low shear rate (LSR) and high shear rate (HSR). Multiple regression analysis demonstrated an independent association between WBV and stroke when adjusted for other risk factors.

CONCLUSIONS

WBV appears to be a profitable predictor of ischemic stroke in patients with NVAF receiving OAC.

The predictive value of MAPH score for determining thrombus burden in patients with non-ST segment elevation myocardial infarction

Background

A high thrombus burden has been connected with poor clinical events in patients with non-ST segment elevation myocardial infarction (NSTEMI). In patients with STEMI, a high MAPH score has been associated with a large thrombus burden. However, the predictive value of the MAPH score in determining the thrombus burden in patients with NSTEMI is unclear. The present report aimed to evaluate the prognostic role of the MAPH score in the estimating coronary thrombus burden in NSTEMI patients. The study patients were split into two groups according to their thrombus grade. The low shear rate (LSR) and high shear rate (HSR) were estimated by haematocrit levels and serum total protein levels. The MAPH score was calculated by adding mean platelet volume (MPV) levels and age, in addition to total protein and haematocrit.

Results

The patients with a high thrombus burden (HTB) had a higher LSR, higher HSR and higher MAPH score compared to patients with low thrombus burden. MAPH score was found to be an independent predictors of HTB in Model 1 (OR: 1.124, 95% CI: 1.011–1.536; p = 0.039) and Model 2 (OR: 1.236; 95% CI: 1.002–1.525; p = 0.047). The cut-off value of the MAPH score for predicting HTB was 2 based on the Youden index.

Conclusions

The MAPH score, which calculated by adding MPV levels and age, in addition to total protein and haematocrit, is a novel, easily accessible score. The MAPH score at both LSR and HSR was an independent predictor of HTB.

The Influence of High Blood Pressure on Developing Symptomatic Lumbar Epidural Hematoma after Posterior Lumbar Spinal Fusion Surgery: Clinical Data Warehouse Analysis

Background: Determining the risk factors for symptomatic lumbar epidural hematoma (SLEH) is important for preventing postoperative SLEH. However, the relationship between blood pressure and SLEH is still debatable. The purpose of our study was to determine the risk factors for postoperative SLEH, to assess the influence of high blood pressure on developing SLEH after posterior lumbar spinal fusion surgery, and to evaluate the usefulness of big data analysis utilizing a clinical data warehouse (CDW). Methods: The clinical data of patients who had undergone posterior lumbar spinal fusion surgery were acquired from the CDW of Hallym University Medical Center. The acquired clinical data were compared between patients without postoperative SLEH and with postoperative SLEH. Results: Postoperative SLEH that required hematoma evacuation surgery within 72 h after posterior lumbar spinal fusion surgery occurred in 17 (1.3%) of 1313 patients. According to the multivariate logistic regression analysis, the risk factors for postoperative SLEH are platelet count difference (OR 1.28, p = 0.03), postoperative international normalized ratio (INR) difference (OR 31.4, p = 0.028), and postoperative systolic blood pressure (SBP) difference (≥10 mmHg) (OR 1.68, p = 0.048). An increase in postoperative SBP (OR 1.68, p = 0.048) had a statistically significant influence on the occurrence of postoperative SLEH. Conclusions: Big data analysis utilizing a CDW could be useful for extending our knowledge of the risk factors for postoperative SLEH and preventing postoperative SLEH after posterior lumbar spinal fusion surgery.

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.

Global Reach 2018: sympathetic neural and hemodynamic responses to submaximal exercise in Andeans with and without chronic mountain sickness

Andeans with chronic mountain sickness (CMS) and polycythemia have similar maximal oxygen uptakes to healthy Andeans. Therefore, this study aimed to explore potential adaptations in convective oxygen transport, with a specific focus on sympathetically mediated vasoconstriction of nonactive skeletal muscle. In Andeans with (CMS+, n = 7) and without (CMS-, n = 9) CMS, we measured components of convective oxygen delivery, hemodynamic (arterial blood pressure via intra-arterial catheter), and autonomic responses [muscle sympathetic nerve activity (MSNA)] at rest and during steady-state submaximal cycling exercise [30% and 60% peak power output (PPO) for 5 min each]. Cycling caused similar increases in heart rate, cardiac output, and oxygen delivery at both workloads between both Andean groups. However, at 60% PPO, CMS+ had a blunted reduction in Δtotal peripheral resistance (CMS-, -10.7 ± 3.8 vs. CMS+, -4.9 ± 4.1 mmHg·L-1·min-1; P = 0.012; d = 1.5) that coincided with a greater Δforearm vasoconstriction (CMS-, -0.2 ± 0.6 vs. CMS+, 1.5 ± 1.3 mmHg·mL-1·min-1; P = 0.008; d = 1.7) and a rise in Δdiastolic blood pressure (CMS-, 14.2 ± 7.2 vs. CMS+, 21.6 ± 4.2 mmHg; P = 0.023; d = 1.2) compared with CMS-. Interestingly, although MSNA burst frequency did not change at 30% or 60% of PPO in either group, at 60% Δburst incidence was attenuated in CMS+ (P = 0.028; d = 1.4). These findings indicate that in Andeans with polycythemia, light intensity exercise elicited similar cardiovascular and autonomic responses compared with CMS-. Furthermore, convective oxygen delivery is maintained during moderate-intensity exercise despite higher peripheral resistance. In addition, the elevated peripheral resistance during exercise was not mediated by greater sympathetic neural outflow, thus other neural and/or nonneural factors are perhaps involved.NEW & NOTEWORTHY During submaximal exercise, convective oxygen transport is maintained in Andeans suffering from polycythemia. Light intensity exercise elicited similar cardiovascular and autonomic responses compared with healthy Andeans. However, during moderate-intensity exercise, we observed a blunted reduction in total peripheral resistance, which cannot be ascribed to an exaggerated increase in muscle sympathetic nerve activity, indicating possible contributions from other neural and/or nonneural mechanisms.

Albumin, Oral Contraceptives, and Venous Thromboembolism Risk in Astronauts

BACKGROUND

A venous thromboembolism (VTE) event occurred in a female astronaut during long-duration spaceflight. Multiple factors may have contributed to this risk, including the use of combined (progestin + estrogen) oral contraceptives (cOC).

METHODS

Biochemistry data from 65 astronauts were evaluated for associations with cOC use and with sex.

RESULTS

The female astronauts who used cOCs had lower concentrations of serum albumin and higher concentrations of transferrin, a protein involved in the clotting cascade, than the male astronauts and the female astronauts who were not taking cOCs (P<0.001). The women who used cOCs had higher serum concentrations of the acute phase reactant ceruloplasmin during flight and cortisol (P<0.001) than the men and the women who were not taking cOCs; they also had higher calculated whole blood viscosity than women not taking cOCs (P<0.001).

CONCLUSIONS

Lower circulating concentrations of albumin, higher concentrations of transferrin, and elevated markers of inflammation all could contribute to an increased risk of VTE during spaceflight. These changes, in association with a higher blood viscosity can directly affect endothelial glycocalyx integrity and hypercoagulability status, both of which contribute to VTE risk in terrestrial populations.

Young, non-hispanic black men and women exhibit divergent peripheral and cerebral vascular reactivity

NEW FINDINGS

What is the central question of the study? Does peripheral and cerebral vascular function differ in young, non-Hispanic Black men and women? What is the main finding and its importance? The non-Hispanic, Black women in this study presented greater peripheral conduit artery and cerebrovascular reactivity, yet similar peripheral microvascular function relative to the non-Hispanic, Black men. These preliminary findings suggest that young, Black women and men possess divergent vascular function, possibly contributing to the unique non-Hispanic Black sex differences in cardiovascular and cerebrovascular diseases.

ABSTRACT

In the U.S., cardiovascular and cerebrovascular diseases remain more prominent in the non-Hispanic Black (BL) population relative to other racial/ethnic groups. Typically, sex differences emerge in the manifestation of these diseases, though these differences may not fully materialize in the BL population. While numerous mechanisms are implicated, differences in vascular function likely contribute. Research has demonstrated blunted vasodilation in several vascular regions in BL versus non-Hispanic White individuals, though much of this work did not assess sex differences. Therefore, this study aimed to ascertain if indices of vascular function are different between young, BL women (BW) and men (BM). Eleven BW and 15 BM (22 (4) vs. 23 (3) y) participated in this study. Each participant underwent testing for brachial artery flow-mediated dilation (FMD), post-occlusive reactive hyperemia (RH), and cerebral vasomotor reactivity during rebreathing-induced hypercapnia. BW exhibited greater adjusted FMD than BM (P < 0.05 for all), but similar or lower RH when assessed as blood velocity (P > 0.39 for all) or blood flow reactivity (P < 0.05 for all), respectively. Across a range of hypercapnia, BW had greater middle cerebral artery blood velocity and cerebrovascular conductance index than BM (P < 0.001 for both). These preliminary data suggest that young, BW have greater vascular function relative to young, BM, though this was inconsistent across different indices. These findings provide insight into the divergent epidemiological findings between BM and BW. Further research is needed to elucidate possible mechanisms and relate these physiological responses to epidemiological observations. This article is protected by copyright. All rights reserved.

Amontons-Coulomb-like slip dynamics in acousto-microfluidics

Acousto-microfluidics uses acoustic waves to manipulate and sense particles and fluids, and its integration into biomedical technologies has grown substantially in recent years. Fluid manipulation and measurement with surface acoustic waves rely on the efficient transmission of acoustic energy from the device to the fluid. Acoustic transmission into the fluid can be reduced significantly by slip at the fluid-solid interface, but, up until now, this phenomenon has been widely neglected during the design of acousto-microfluidic devices. Here our interpretation supports that the slip dynamics at the liquid-solid interface in acousto-microfluidics are highly analogous to the Amontons-Coulomb laws for dry friction between solids. In particular, there is a relationship between the local fluid pressure and shear stress, where we show that pressure-shear stress conditions can be divided into slip and no-slip regions, similar to the cone of friction found in dry friction. This improved understanding of slip will enable more reliable and predictable acousto-microfluidic technologies, thus expanding their use in new applications in biology and medicine.

Acoustic waves can be used to manipulate particles and fluids in biomedical applications. The authors show that slip at the fluid-solid interface, characterized by a lower acoustic transmission into the fluid, is similar to Amontons-Coulomb friction, as found between solids. 

A case report of left ventricular thrombus formation following aggressive decongestion treatment

Background

Intracardiac thrombi are a complication associated with cardiomyopathies. In heart failure with reduced ejection fraction, there is a hypercoagulable state that can increase the incidence of left ventricular thrombus and result in higher risk of thromboembolism, either manifested as stroke or as peripheral thromboembolic event. Haemoconcentration following decongestion treatment may enhance blood viscosity.

Case summary

A 63-year-old man with known long-standing heart failure (HF) of ischaemic aetiology and not any prothrombotic risk, admitted with congestive HF and treated with aggressive decongestion treatment with intravenous loop diuretics. During his hospital stay, and following decongestion and haemoconcentration, a left ventricular (LV) intracardiac thrombus formation was detected by echocardiography, which occurred in the absence of a recent myocardial infarction or adverse LV remodelling. The patient was treated with oral anticoagulation therapy. There was a complete resolution of the thrombus on repeat transthoracic echocardiography after 4 weeks of treatment.

Discussion

Aggressive decongestive treatment, haemoconcentration and increased blood viscosity following HF decompensation may serve as a trigger for intracardiac thrombus formation under the appropriate prothrombotic background. Appropriate primary antithrombotic prophylaxis is an issue raised concerns and vulnerable patients need closed clinical and imaging follow-up.

The effect of whole blood viscosity on contrast-induced nephropathy development in patients undergoing percutaneous coronary intervention

OBJECTIVE

In our study, we aimed to investigate how whole blood viscosity (WBV) affects the development of contrast-induced nephropathy (CIN) in patients undergoing percutaneous coronary intervention (PCI).

METHODS

In our study, 500 patients who applied to the cardiology clinic and underwent PCI for elective procedure, ST segment elevation myocardial infarction (STEMI), and non-STEMI were prospectively included. Before the procedure, we calculated WBV using the formula [(0.12× hematocrit) + (0.17×(total protein - 2.07)]. We defined CIN as the absolute (≥0.5 mg/dl) or relative increase (≥25%) in serum creatinine 48-72 h after exposure to a contrast agent compared with baseline serum creatinine values.

RESULTS

CIN was developed in 69 (13.6%) of the 500 patients in the study. PCI was performed in 206 patients (41.2%) electively, 175 (35%) due to non-STEMI, and 119 (23%) due to STEMI. CIN was observed in 20.2% of the STEMI group, 13.7% of the non-STEMI group, and 10.2% of the elective PCI group. Multivariate logistic regression analysis results show that the independent predictors of CIN are low ejection fraction [OR:0.95 (95% CI:0.92-0.97); p < 0.001], low glomerular filtration rate [OR:0.96 (95% CI:0.95-0.98); p < 0.001], and increased amount of contrast agent [OR:1.008 (95% CI:1.004-1.01); p < 0.001]. When all patients were examined, no significant relationship was found between WBV and CIN. However, in the subgroup evaluation, it was concluded that low WBV was an independent predictor in elective PCI patients [OR:0.60 (95% CI:0.36-0.99); p = 0.04] for CIN.

CONCLUSION

We found that low WBV was an independent predictor of CIN in patients undergoing elective PCI(NCT04703049).

Whole blood viscosity in patients with aortic stenosis

Whole blood viscosity (WBV) may promote endothelial shear stress, inflammation, and can accelerate the atherosclerotic process. We aimed to evaluate the relationship between WBV and aortic stenosis. The study included 209 participants of whom 49 patients had severe aortic stenosis, 98 patients had mild-to-moderate aortic stenosis and 62 patients served as control. WBV values were significantly higher for high shear rate (HSR) (P = 0.001) and for low shear rate (LSR) (P = 0.002) in severe aortic stenosis group. HSR and LSR were correlated with mean systolic transaortic gradient (P < 0.001 and P < 0.001, respectively). WBV for both LSR and HSR were found to be independent predictors for the aortic stenosis severity (P = 0.034 and P = 0.049, respectively). We found a significant relationship between WBV and aortic stenosis.

Hemoglobin and hematocrit levels are positively associated with blood pressure in children and adolescents 10 to 18 years old

To investigate the associations between hemoglobin (Hb) concentration and hematocrit (Hct), and blood pressure (BP) in children and adolescents. The study population consisted of 7950 subjects total (4229 boys and 3721 girls) aged 10-18 years who participated in the Korea National Health and Nutrition Examination Surveys conducted between 2007 and 2017. The prevalence of hypertension was 19.19% (21.51% for boys and 16.5% for girls) among the study population, and the prevalence of obesity was 9.59% (10.5% for boys and 8.6% for girls). Hb count and Hct tended to increase with the degree of obesity and BP elevation. Systolic BP (SBP) and diastolic BP (DBP) positively correlated with Hb count and Hct in both sexes. Following multiple linear regression analysis, Hb count and Hct presented a positive association with SBP and DBP after adjusting for age, BMI SDS, alcohol consumption, smoking status, physical activity, rural residence, household income, diagnosis of T2DM, hypertension, and dyslipidemia. Hb count and Hct were positively associated with SBP and DBP in children and adolescents 10-18 years old.

Global REACH 2018: the adaptive phenotype to life with chronic mountain sickness and polycythaemia

KEY POINTS

Humans suffering from polycythaemia undergo multiple circulatory adaptations including changes in blood rheology and structural and functional vascular adaptations to maintain normal blood pressure and vascular shear stresses, despite high blood viscosity. During exercise, several circulatory adaptations are observed, especially involving adrenergic and non-adrenergic mechanisms within non-active and active skeletal muscle to maintain exercise capacity, which is not observed in animal models. Despite profound circulatory stress, i.e. polycythaemia, several adaptations can occur to maintain exercise capacity, therefore making early identification of the disease difficult without overt symptomology. Pharmacological treatment of the background heightened sympathetic activity may impair the adaptive sympathetic response needed to match local oxygen delivery to active skeletal muscle oxygen demand and therefore inadvertently impair exercise capacity.

ABSTRACT

Excessive haematocrit and blood viscosity can increase blood pressure, cardiac work and reduce aerobic capacity. However, past clinical investigations have demonstrated that certain human high-altitude populations suffering from excessive erythrocytosis, Andeans with chronic mountain sickness, appear to have phenotypically adapted to life with polycythaemia, as their exercise capacity is comparable to healthy Andeans and even with sea-level inhabitants residing at high altitude. By studying this unique population, which has adapted through natural selection, this study aimed to describe how humans can adapt to life with polycythaemia. Experimental studies included Andeans with (n = 19) and without (n = 17) chronic mountain sickness, documenting exercise capacity and characterizing the transport of oxygen through blood rheology, including haemoglobin mass, blood and plasma volume and blood viscosity, cardiac output, blood pressure and changes in total and local vascular resistances through pharmacological dissection of α-adrenergic signalling pathways within non-active and active skeletal muscle. At rest, Andeans with chronic mountain sickness had a substantial plasma volume contraction, which alongside a higher red blood cell volume, caused an increase in blood viscosity yet similar total blood volume. Moreover, both morphological and functional alterations in the periphery normalized vascular shear stress and blood pressure despite high sympathetic nerve activity. During exercise, blood pressure, cardiac work and global oxygen delivery increased similar to healthy Andeans but were sustained by modifications in both non-active and active skeletal muscle vascular function. These findings highlight widespread physiological adaptations that can occur in response to polycythaemia, which allow the maintenance of exercise capacity.

Comparison between whole blood viscosity measured and calculated in subjects with monoclonal gammopathy of undetermined significance and in patients with multiple myeloma: Re-evaluation of our survey

BACKGROUND

in this study, with a re-evaluation of the hemorheological determinants previously described in MGUS subjects and in MM patients, we have detected the calculated whole blood viscosity, according whether to the hematocrit and total plasma protein concentration (de Simone formula) or to the haematocrit and plasma fibrinogen level (Merrill formula), and a marker of the erythrocyte aggregation (albumin/fibrinogen level).

METHODS

data were expressed as means±standard deviation. Student's t test for unpaired data was used to compare MGUS subjects and MM patients. The correlation coefficient between mean erythrocyte aggregation (MEA) and hematocrit (Ht) was evaluated in MGUS, MM and MGUS + MM groups using the Spearman test.

RESULTS

the comparison between MGUS and MM shows that the measured blood viscosity and calculated blood viscosity based on hematocrit and total plasma protein, but not which estimated in relation to the hematocrit and plasma fibrinogen, differentiate the two groups. A difference between the two groups also regards the measured erythrocyte aggregation and its surrogate marker. In addition, the measured plasma viscosity at low shear rate (0.51 s-1) and, in particular, the ratio between plasma viscosity at low (0.51 s-1) and high (450 s-1) shear rates distinguish MGUS and MM.

CONCLUSIONS

calculated blood viscosity (de Simone formula and other formulas) and the surrogate marker of erythrocyte aggregation disclose an alike trend with the corresponding hemorheological determinants obtained by using their direct measurement.

Relationship between Whole Blood Viscosity and Lesion Severity in Coronary Artery Disease

Objective  This article investigates the relationship of fractional flow reserve (FFR) with whole blood viscosity (WBV) in patients who were diagnosed with chronic coronary syndrome and significant stenosis in the major coronary arteries and underwent the measurement of FFR. Material and Method  In the FFR measurements performed to evaluate the severity of coronary artery stenosis, 160 patients were included in the study and divided into two groups as follows: 80 with significant stenosis and 80 with nonsignificant stenosis. WBVs at low shear rate (LSR) and high shear rate (HSR) were compared between the patients in the significant and nonsignificant coronary artery stenosis groups. Results  In the group with FFR < 0.80 and significant coronary artery stenosis, WBV was significantly higher compared with the group with nonsignificant coronary artery stenosis in terms of both HSR (19.33 ± 0.84) and LSR (81.19 ± 14.20) ( p  < 0.001). In the multivariate logistic regression analysis, HSR and LSR were independent predictors of significant coronary artery stenosis (HSR: odds ratio: 1.67, 95% confidence interval: 1.17-2.64; LSR: odds ratio: 2.46, 95% confidence interval: 2.19-2.78). In the receiver operating characteristic (ROC) curve analysis, when the cutoff value of WBV at LSR was taken as 79.23, it had 58.42% sensitivity and 62.13% specificity for the prediction of significant coronary artery stenosis (area under the ROC curve: 0.628, p  < 0.001). Conclusion  WBV, an inexpensive biomarker that can be easily calculated prior to coronary angiography, was higher in patients with functionally severe coronary artery stenosis, and thus could be a useful marker in predicting the hemodynamic severity of coronary artery stenosis in patients with chronic coronary syndrome.

Relationship between blood viscosity and no-reflow phenomenon in ST-segment elevation myocardial infarction performed in primary percutaneous coronary interventions

Background: This study aimed to analyze the associations between no-reflow (NR) phenomenon development and whole-blood viscosity in patients with ST-elevated myocardial infarction. Methods: A total of 217 patients with ST-elevated myocardial infarction were included. whole-blood viscosity values were assessed using hematocrit and total protein values, and low shear rate (LSR) and high shear rate (HSR) were calculated. Results: The average LSR and HSR values of the study group were significantly higher than the control group (p < 0.001). Multivariate logistic regression analysis showed that both HSR (odds ratio: 4.957; p < 0.001) and LSR (odds ratio: 1.114; p < 0.001) were independent predictors for NR development. Conclusion: This study found that increased blood viscosity was an independent predictor for NR development.

Whole blood viscosity in the evaluation of thrombogenic milieu in mitral stenosis

Aim: We aimed to assess the association of whole blood with thromboembolic milieu in significant mitral stenosis patients. Methodology & results: We included 122 patients and classified patients into two groups as having thrombogenic milieu, thrombogenic milieu (+), otherwise patients without thrombogenic milieu, thrombogenic milieu (-). Whole blood viscosity (WBV) in both shear rates were higher in thrombogenic milieu (+) group comparing with thrombogenic milieu (-). WBV at high shear rate and WBV at low shear rate parameters were moderately correlated with grade of spontaneous echo contrast. Adjusted with other parameters, WBV parameters at both shear rates were associated with presence of thrombogenic milieu. Discussion & conclusion: We found that extrapolated WBV at both shear rates was significantly associated with the thrombogenic milieu in mitral stenosis. This easily available parameter may provide additional perspective about thrombogenic diathesis.

Ex vivo assessment of erythrocyte tolerance to the HeartWare ventricular assist device operated in three discrete configurations

Despite technological advances in ventricular assist devices (VADs) to treat end-stage heart failure, hemocompatibility remains a constant concern, with supraphysiological shear stresses an unavoidable reality with clinical use. Given that impeller rotational speed is related to the instantaneous shear within the pump housing, it is plausible that the modulation of pump speed may regulate peak mechanical shear stresses and thus ameliorate blood damage. The present study investigated the hemocompatibility of the HeartWare HVAD in three configurations typical of clinical applications: standard systemic support left VAD (LVAD), pediatric support LVAD, and pulmonary support right VAD (RVAD) conditions. Two ex vivo mock circulation blood loops were constructed using explanted HVADs, in which pump speed and external loop resistance were manipulated to reflect the flow rates and differential pressures reported in configurations for standard adult LVAD (at 3150 rev⸱min^-1 ), pediatric LVAD (at 2400 rev⸱min^-1 ), and adult RVAD (at 1900 rev⸱min^-1 ). Using bovine blood, the mock circulation blood loops were tested at 37°C over a period of 6 hours (consistent with ASTM F1841-97) and compared with static control. Hemocompatibility assessments were conducted for each test condition, examining hematology, hemolysis (absolute and normalized index), osmotic fragility, and blood viscosity. Regardless of configuration, continuous exposure of blood to the VAD over the 6-hour period significantly altered hematological and rheological blood parameters, and induced increased hemolysis when compared with a static control sample. Comparison of the three operational VAD configurations identified that the adult LVAD condition-associated with the highest pump speed, flow rate, and differential pressure across the pump-resulted in increased normalized hemolysis index (NIH; 0.07) when compared with the lower pump speed "off-label" counterparts (NIH of 0.04 in pediatric LVAD and 0.01 in adult RVAD configurations). After normalizing blood residence times between configurations, pump speed was identified as the primary determinant of accumulated blood damage; plausibly, blood damage could be limited by restricting pump speed to the minimum required to support matched cardiac output, but not beyond.

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.

Heritability of haemodynamics in the ascending aorta

Blood flow in the vasculature can be characterised by dimensionless numbers commonly used to define the level of instabilities in the flow, for example the Reynolds number, Re. Haemodynamics play a key role in cardiovascular disease (CVD) progression. Genetic studies have identified mechanosensitive genes with causal roles in CVD. Given that CVD is highly heritable and abnormal blood flow may increase risk, we investigated the heritability of fluid metrics in the ascending aorta calculated using patient-specific data from cardiac magnetic resonance (CMR) imaging. 341 participants from 108 British Caucasian families were phenotyped by CMR and genotyped for 557,124 SNPs. Flow metrics were derived from the CMR images to provide some local information about blood flow in the ascending aorta, based on maximum values at systole at a single location, denoted max, and a 'peak mean' value averaged over the area of the cross section, denoted pm. Heritability was estimated using pedigree-based (QTDT) and SNP-based (GCTA-GREML) methods. Estimates of Reynolds number based on spatially averaged local flow during systole showed substantial heritability ([Formula: see text], [Formula: see text]), while the estimated heritability for Reynolds number calculated using the absolute local maximum velocity was not statistically significant (12-13%; [Formula: see text]). Heritability estimates of the geometric quantities alone; e.g. aortic diameter ([Formula: see text], [Formula: see text]), were also substantially heritable, as described previously. These findings indicate the potential for the discovery of genetic factors influencing haemodynamic traits in large-scale genotyped and phenotyped cohorts where local spatial averaging is used, rather than instantaneous values. Future Mendelian randomisation studies of aortic haemodynamic estimates, which are swift to derive in a clinical setting, will allow for the investigation of causality of abnormal blood flow in CVD.

Patient-Specific CT-Based Fluid-Structure-Interaction Aorta Model to Quantify Mechanical Conditions for the Investigation of Ascending Aortic Dilation in TOF Patients

Background

Some adult patients with Tetralogy of Fallot (TOF) were found to simultaneously develop ascending aortic dilation. Severe aortic dilation would lead to several aortic diseases, including aortic aneurysm and dissection, which seriously affect patients' living quality and even cause patients' death. Current practice guidelines of aortic-dilation-related diseases mainly focus on aortic diameter, which has been found not always a good indicator. Therefore, it may be clinically useful to identify some other factors that can potentially better predict aortic response to dilation.

Methods

20 TOF patients scheduled for TOF repair surgery were recruited in this study and were divided into dilated and nondilated groups according to the Z scores of ascending aorta diameters. Patient-specific aortic CT images, pressure, and flow rates were used in the construction of computational biomechanical models.

Results

Simulation results demonstrated a good coincidence between numerical mean flow rate at inlet and the one obtained from color Doppler ultrasonography, which implied that computational models were able to simulate the movement of the aorta and blood inside accurately. Our results indicated that aortic stress can effectively differentiate patients of the dilated group from the ones of the nondilated group. Mean ascending aortic stress-P1 (maximal principal stress) from the dilated group was 54% higher than that from the nondilated group (97.97 kPa vs. 63.47 kPa, p value = 0.044) under systolic pressure. Velocity magnitude in the aorta and aortic wall displacement of the dilated group were also greater than those of the nondilated group with p value < 0.1.

Conclusion

Computational modeling and ascending aortic biomechanical factors may be used as a potential tool to identify and analyze aortic response to dilation. Large-scale clinical studies are needed to validate these preliminary findings.

Cell-Free Hemoglobin Is Associated With Increased Vascular Resistance and Reduced Peripheral Perfusion in Severe Malaria

BACKGROUND

In severe falciparum malaria, unlike sepsis, hypotension on admission is uncommon. We hypothesized that low nitric oxide bioavailability due to the presence of cell-free hemoglobin (CFH) increases vascular tone in severe malaria.

METHODS

Patients with severe malaria (n = 119), uncomplicated malaria (n = 91), or suspected bacterial sepsis (n = 56), as well as healthy participants (n = 50), were recruited. The systemic vascular resistance index (SVRI) was estimated from the echocardiographic cardiac index and the mean arterial pressure.

RESULTS

SVRI and hematocrit levels were lower and plasma CFH and asymmetric dimethylarginine levels were higher in patients with malaria, compared with healthy participants. In multivariate linear regression models for mean arterial pressure or SVRI in patients with severe malaria, hematocrit and CFH but not asymmetric dimethylarginine were significant predictors. The SVRI was lower in patients with suspected bacterial sepsis than in those with severe malaria, after adjustment for hematocrit and age. Plasma CFH levels correlated positively with the core-peripheral temperature gradient and plasma lactate levels and inversely with the perfusion index. Impaired peripheral perfusion, as reflected by a low perfusion index or a high core-peripheral temperature gradient, predicted mortality in patients with severe malaria.

CONCLUSIONS

CFH is associated with mean arterial pressure, SVRI, and peripheral perfusion in patients with severe malaria. This may be mediated through the nitric oxide scavenging potency of CFH, increasing basal vascular tone and impairing tissue perfusion.

Hematocrit, hemoglobin and red blood cells are associated with vascular function and vascular structure in men

High and low hematocrit (Hct) and hemoglobin (Hb) levels are associated with the risk of cardiovascular disease. The purpose of this study was to determine the relationships of Hct, Hb and red blood cells (RBCs) with vascular function and structure. We measured flow-mediated vasodilation (FMD), nitroglycerin-induced vasodilation (NID), brachial intima media thickness (IMT), and brachial-ankle pulse wave velocity (baPWV) in 807 men. The subjects were divided into six groups according to the levels of Hct, Hb and RBCs. NID was highest in the 46.0–48.9% Hct group among the six groups according to Hct levels. Brachial IMT was lowest in the 46.0–48.9% Hct group among the six groups. There were no significant differences in FMD and baPWV among the six groups. We used 46.0–48.9% Hct as a reference to define the lower tertile. The adjusted odds ratio of being in the low tertile of NID was significantly higher in the < 42.9% and ≥ 49.0% Hct groups. Adjusted odds ratio of being in the low tertile of brachial IMT was significantly lower in the < 39.9% Hct groups. Similar results were obtained for Hb and RBCs. Low and high levels of Hct, Hb and RBCs were associated with vascular smooth muscle dysfunction, and low Hct levels were associated with abnormal vascular structure. Increases in the levels of Hct, Hb and RBCs within normal ranges may have beneficial effects on the vasculature.

Usefulness of whole blood viscosity estimated by de Simeone's formula to predict left ventricular thrombus formation within one year following acute anterior myocardial infarction

BACKGROUND

Despite improvements in treatment of ST-segment myocardial infarction (STEMI), thrombus formation in the left ventricle is still a concerning complication that may lead to systemic thromboembolism and stroke.

OBJECTIVES

To evaluate the predictive value of estimated whole blood viscosity (WBV) for left ventricular thrombus development in patients surviving an acute anterior myocardial infarction (AAMI).MATERIALS \& METHODS:Seven hundred eighty AAMI patients who were treated percutaneously were enrolled consecutively. Serial echocardiographic examinations were performed within 24h of admission, before hospital discharge, and at 1, 3, 6 and 12 months following hospital discharge. WBV was calculated according to de Simones formula.

RESULTS

One hundred patients (12.8%) developed thrombus formation within one year following AAMI. Patients with left ventricular thrombus (LVT) had significantly higher WBV values. Supramedian values of WBV at both low (0.5 sec-1) and high (208 sec-1) shear rates were found to be an independent predictor of LVT development.

CONCLUSION

As an easily accessible parameter, WBV might be a useful predictor of LVT formation within one year following acute anterior myocardial infarction.

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.

The Relationship between Blood Viscosity and Acute Arterial Occlusion

Background: Blood viscosity is a strong predictor of cardiovascular events. However, the relationship between blood viscosity and acute arterial occlusion (AAO) has not been studied adequately so far.

Objectives: The aim of the present study was to assess the relationship between whole blood viscosity (WBV) and AAO.

Material and methods: The study included 93 patients who were diagnosed with AAO between January 2017 and September 2019, and 90 age- and sex-matched healthy controls. WBV was assessed using a validated calculation formula derived from hematocrit and total plasma protein levels, both as a low (LSR) and a high (HSR) shear rate.

Results: There were no significant differences between the two groups in regards to the baseline characteristics, with the exception of smoking and LDL cholesterol levels. Subjects with AAO presented significantly higher WBV values both at LSR (32.2 ± 5.0 vs. 26.6 ± 5.0, p <0.001) and HSR (6.2 ± 0.3 vs. 5.7 ± 0.3, p <0.001). The ROC analysis revealed a cut-off value of 27.4 for WBV at LSR (sensitivity 66%, specificity 64%, AUC = 0.770, p <0.001) and a cut-off value of 5.29 in case of HSR (sensitivity 69%, specificity 74%, AUC = 0.801, p <0.001) for predicting AAO. Multivariate analysis, both LSR (OR 3.33, 95% CI: 1.20–9.43, p = 0.006) and HSR (p = 0.020, OR: 1.70, 95% CI: 1.020–1.123) were independent predictors of AAO.

Conclusions: This study demonstrated that WBV levels at both HSR and LSR are significantly higher in the AAO group than in the control subjects, indicating that an increased WBV may be associated with the development of AAO.

Relationship between apical thrombus formation and blood viscosity in acute anterior myocardial infarction patients

Aim: This study sought to investigate the predictive value of whole blood viscosity (WBV) to identify high-risk patients who will develop an apical thrombus during the acute phase of anterior transmural infarction. Materials & methods: Consecutive 1726 patients with first acute anterior myocardial infarction were evaluated. WBV was calculated according to the Simone’s formula. Results: Patients with an apical thrombus had prolonged pain to balloon time, higher rate of post-PCI thrombolysis in myocardial infarction flow ≤1 and significantly higher mean WBV values at both shear rates than those without an apical thrombus. Conclusion: WBV values at both shear rates were found to be significant and independent predictors for early LV apical thrombus formation complicating a first-ever anterior wall myocardial infarction.

Whole blood viscosity is an independent early predictor for metabolic syndrome and its components in men: A prospective cohort study in Northern Chinese population

The association between whole blood viscosity (WBV) and metabolic syndrome (MetS) is still scarcely investigated in the population-based prospective cohort. We aim to explore the longitudinal effect of WBV on MetS, and to verify whether WBV measures can be used as early predictors for MetS. The longitudinal cohort consisted of 3,508 adults (2,350 males and 1,158 females) who visited the health check-up system twice. WBV were measured at four shear rate (200, 50, 10 and 1 s-1), and their values were classified into quartiles. Multivariate Cox models were used to estimate the adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) in men and women, respectively. A total of 444 (12.66%) incident MetS were observed at follow-up period. The incidences of MetS significantly increased with increasing quartiles of WBVs at all of the shear rate in men. After adjusting for baseline age, smoking, obesity, hypertension, hyperglycemia, and hyperlipidemia status, all of the WBV measures were significantly associated with incident MetS in men, and the HRs showed clear increasing trend across the quartiles of baseline WBVs. There were no significant association between WBVs and incident MetS in women. These findings suggest that MetS has a hemodynamic basis, and WBVs could be used as independent early predictor for MetS in men.

Arterial and venous thrombosis by high platelet count and high hematocrit: 108 521 individuals from the Copenhagen General Population Study

BACKGROUND

It is unclear whether high platelet count or high hematocrit predict risk of thrombosis in individuals from the general population.

OBJECTIVES

We tested the hypothesis that individuals from the general population with high platelet count or high hematocrit have high risk of arterial and venous thrombosis.

METHODS

We prospectively followed 108 521 individuals from The Copenhagen General Population Study for a median of 8 years. Platelet count and blood hematocrit were measured at study entry.

RESULTS AND CONCLUSION

Multivariable adjusted hazard ratios for individuals with platelet counts in the top 5 percentiles (>398 × 109 /L) vs in the 25th-75th percentiles (231-316 × 109 /L) were 1.77 (95% confidence interval [CI], 1.38-2.24) for arterial thrombosis in the brain (38 and 26 events/10 000 person-years) and 0.82 (95%, 0.61-1.11) for arterial thrombosis in the heart (23 and 28 events/10 000 person-years). For individuals with hematocrit values in the top 5 percentiles (women/men: >45/>48%) vs the 25th-75th percentiles (women/men: 38.1-42/41.1-45%), hazard ratios were 1.27 (95% CI, 0.91-1.75) for arterial thrombosis in the brain (40 and 26 events/10 000 person-years) and 1.46 (95% CI, 1.06-2.00) for arterial thrombosis in the heart (43 and 25 events/10 000 person-years). Neither high platelet count nor high hematocrit was associated with risk of venous thromboembolism. When excluding individuals with myeloproliferative neoplasia from the main analyses, results on risk of thrombosis were similar. In this prospective study, high platelet counts were associated with 1.8-fold risk of arterial thrombosis in the brain, whereas high hematocrit was associated with 1.5-fold risk of arterial thrombosis in the heart.