Blood rheology in general medicine and surgery

Plasma viscosity, immunoglobulins and risk of cardiovascular disease and mortality: new data and meta-analyses

AIMS

Associations of plasma viscosity and plasma Ig levels (a determinant of viscosity) with incident coronary heart disease (CHD) events; and with CHD, cardiovascular disease (CVD: CHD and stroke) and all-cause mortalities.

METHODS

Meta-analysis of plasma viscosity levels from the MONitoring of trends and determinants of CArdiovascular (MONICA)/Cooperative Health Research in the Region of Augsburg, MONICA Glasgow and Speedwell Studies; and five other published studies. Meta-analysis of IgA, IgG and IgM levels from the Augsburg, Glasgow and Speedwell studies; and one other published study.

RESULTS

Over median follow-up periods of 14-26 years, there were 2270 CHD events, and 4220 all cause deaths in 28 605 participants with baseline plasma viscosity measurements. After adjustment for major risk factors, (HRs; 95% CIs) for a 1 SD increase in viscosity were 1.14 (1.09 to 1.20) for CHD events; and 1.21 (1.17 to 1.25) for all-cause mortality. 821 CHD events and 2085 all-cause deaths occurred in 8218 participants with baseline Ig levels. For CHD events, adjusted HRs for 1 SD increases in IgA, IgG and IgM were, respectively, 0.97 (0.89 to 1.05); 0.95(0.76 to 1.17) and 0.90 (0.79 to 1.03). Corresponding adjusted HRs for all-cause mortality were 1.08 (95% CI 1.02 to 1.13), 1.03 (95% CI 0.94 to 1.14) and 1.01 (95% CI 0.96 to 1.06).

CONCLUSIONS

After risk factor adjustment, plasma viscosity was significantly associated with risks of CHD events; and with CHD, CVD and all-cause mortalities. We found no significant association of IgA, IgG or IgM levels with incident CHD events or mortality, except for a borderline association of IgA with all-cause mortality.

Association between blood viscosity and early neurological deterioration in lacunar infarction

Background

Understanding the factors related to early neurologic deterioration (END) is crucial in the management of patients with lacunar infarction. Blood viscosity is a significant factor for microvascular perfusion. We investigated the association between blood viscosity and occurrence of END in lacunar infarction.

Methods

We included consecutive patients admitted for lacunar infarction within 72 h from symptoms onset. END was defined as an increase in the National Institute of Health Stroke Scale (NIHSS) score ≥2 within 24 h of admission. Viscosity was measured within 24 h of hospitalization with a scanning capillary tube viscometer. Viscosity measured at a shear rate of 300 s⁻¹ was defined as systolic blood viscosity (SBV), whereas that measured at a shear rate of 5 s⁻¹ as diastolic blood viscosity (DBV).

Results

Of the 178 patients included (median age, 65.5; interquartile range [IQR], 56.0, 76.0], END occurred in 33 (18.5%). DBV was significantly higher in patients with END than those without END (13.3 mPa·s [IQR 11.8, 16.0] vs. 12.3 mPa·s [IQR11.0, 13.5]; P = 0.023). In the multivariate analysis, DBV was independently associated with the occurrence of END (odds ratio 1.17; 95% confidence interval 1.01–1.36; P = 0.043). Subgroup analysis showed no heterogeneity in the effect of viscosity on the occurrence of END.

Conclusions

Blood viscosity at a low shear rate (DBV) was associated with the occurrence of END in patients with lacunar infarction. Blood rheology may be important in pathophysiology of END in patients with lacunar infarction.

Short-term effects of cold spells on plasma viscosity: Results from the KORA cohort study in Augsburg, Germany

As the underlying mechanisms of the adverse effects of cold spells on cardiac events are not well understood, we explored the effects of cold spells on plasma viscosity, a blood parameter linked to cardiovascular disease. This cross-sectional study involved 3622 participants from the KORA S1 Study (1984-1985), performed in Augsburg, Germany. Exposure data was obtained from the Bavarian State Office for the Environment. Cold spells were defined as two or more consecutive days with daily mean temperatures below the 3^rd, 5^th, or 10^th percentile of the distribution. The effects of cold spells on plasma viscosity were explored by generalized additive models with distributed lag nonlinear models (DLNM). We estimated cumulative effects at lags 0-1, 0-6, 0-13, 0-20, and 0-27 days separately. Cold spells (mean temperature <3^rd, <5^th or <10^th percentile) were significantly associated with an increase in plasma viscosity with a lag of 0-1 days [%change of geometric mean (95% confidence interval): 1.35 (0.06-2.68), 1.35 (0.06-2.68), and 2.49 (0.34-4.69), respectively], and a lag of 0-27 days [18.81 (8.97-29.54), 17.85 (8.29-28.25), and 7.41 (3.35-11.0), respectively]. For the analysis with mean temperature <3^rd or 10^th percentile, we also observed significant associations at lag 0-20 days [8.34 (0.43-16.88), and 4.96 (1.68, 8.35), respectively]. We found that cold spells had significant immediate and longer lagged effects on plasma viscosity. This finding supports the complex interplay of multiple mechanisms of cold on adverse cardiac events and enriches the knowledge about how cold exposure acts on the human body.

Defibrinogen Therapy for Acute Ischemic Stroke: 1332 Consecutive Cases

This study aimed to examine the effectiveness of defibrinogen therapy on functional recovery and safety among 1332 consecutive ischemic stroke patients who had not received intravenous thrombolysis with recombinant tissue plasminogen activator. Stroke patients undergoing conservative and relatively individualized multiple-day dosing regimens of defibrinogen therapy between January 1, 2008 and May 30, 2016 were enrolled. Data were analyzed according to functional success (Barthel Index of 95 or 100, mRS of 0 or 1) and safety variables (intracranial hemorrhage, mortality and stroke recurrence). At 12 months, 18.62% (203/1087) of patients were lost to follow-up. The functional success rates were 39.84% (526/1320) and 42.23% (459/1087) as assessed by BI at 3 months and 12 months, respectively. Fifteen patients had asymptomatic intracranial hemorrhage within 24 hours after the initial defibrase administration. During the 14 days after hospitalization, 12 patients were diagnosed with symptomatic intracranial hemorrhage (sICH) and a total of 12 patients died from all causes. At 3 months, 56 patients were dead and 21 patients had recurrent stroke. The percentage of death and recurrence of stroke at 12 months were 6.81% and 3.22%, respectively. Results from the historical control showed no significant differences of functional success were detected between the patients treated with rt-PA within 6 hours of stroke onset in NINDS II and the patients treated with defibrase within 6 hours after stroke in the present study. The multiple-day dosing regimen of defibrinogen therapy using defibrase applied in the present study could achieve functional improvement among acute ischemic stroke patients, with low risks of mortality when compared with other similar studies. However, the efficacy and safety of such a defibrinogenating therapy is needed to be verified by RCTs with large sample size.

Hyperviscosity in renal transplant recipients

OBJECTIVE

The resistance of blood to flow is called plasma viscosity. Increased blood viscosity has been described in patients with coronary and peripheral arterial disease. In this study, we evaluated the influence of clinical and laboratory findings on plasma viscosity in renal transplant recipients.

METHODS

Eighty-one kidney transplant recipients (37.8 ± 11.3 years old, 50.38 ± 16.8 months post-transplantation period, 27 female) with normal graft functions were enrolled. The biochemical and clinical parameters in the 1st year after transplantation were retrospectively recorded, and graft function was evaluated by means of the yearly decline in eGFR. Plasma viscosity was measured and searched for the association with cross-sectionally analyzed cardiovascular parameters including body composition analyses, ambulatory blood pressure monitoring (ABPM) data, and pulse-wave velocity.

RESULTS

Patients were divided into 2 groups according to the median value of serum viscosity. Patients with high viscosity had higher serum low-density lipoprotein (P = .042) and C-reactive protein (P = .046) levels than lower viscosity group. In ABPM, daytime (P = .047) and office systolic (P = .046) blood pressure levels and left ventricular mass index (LVMI; P = .012) were significantly higher in patients with hyperviscosity. Patients with high viscosity had higher hip circumference (P = .038) and fat mass (P = .048). Estimated glomerular filtration rate decline was significantly higher in high-viscosity patients than in patients with low viscosity levels (12.9% vs 17.2%; P = .001) at 2 years' follow-up.

CONCLUSIONS

We suggest that the hyperviscous state of the renal transplant recipients may arise from the inflammatory state, hypertension, and increased fat mass and increased LVMI. Hyperviscosity is also closely related to renal allograft dysfunction.

Drag-reducing polyethylene oxide improves microcirculation after hemorrhagic shock

BACKGROUND

Despite resuscitation after trauma, microcirculatory abnormalities are known to persist in post-shock multiorgan dysfunction. The high-molecular weight polymer polyethylene oxide (PEO) (>10(6) Da), a classic drag-reducing polymer, can improve hemorrhagic shock (HS)-induced hemodynamic abnormalities in rats.

MATERIALS AND METHODS

We examined the effects of PEO on microcirculation and on changes in multiple organs after shock. After the spinotrapezius muscle was prepared, HS was induced in Sprague-Dawley rats. Drug administration (normal saline or PEO) was performed 2 h after shock followed by infusion of shed blood.

RESULTS

The velocity, blood flow, and functional capillary density in the shock + PEO group were significantly higher than those in the shock + normal saline group. Moreover, the kidney, liver, and lung function was improved, resulting in prolonged survival time. Our findings indicate that intravenous infusion of PEO can ameliorate shock-associated organ dysfunction and prolong survival time in severe HS, which may be a result of increased arteriolar blood velocity, blood flow, and functional capillary density.

CONCLUSIONS

PEO could have potential clinical application in the treatment of shock-induced multiorgan dysfunction.

Hybrid System for Ex Vivo Hemorheological and Hemodynamic Analysis: A Feasibility Study

Precise measurement of biophysical properties is important to understand the relation between these properties and the outbreak of cardiovascular diseases (CVDs). However, a systematic measurement for these biophysical parameters under in vivo conditions is nearly impossible because of complex vessel shape and limited practicality. In vitro measurements can provide more biophysical information, but in vitro exposure changes hemorheological properties. In this study, a hybrid system composed of an ultrasound system and microfluidic device is proposed for monitoring hemorheological and hemodynamic properties under more reasonable experimental conditions. Biophysical properties including RBC aggregation, viscosity, velocity, and pressure of blood flows are simultaneously measured under various conditions to demonstrate the feasibility and performance of this measurement system. The proposed technique is applied to a rat extracorporeal loop which connects the aorta and jugular vein directly. As a result, the proposed system is found to measure biophysical parameters reasonably without blood collection from the rat and provided more detailed information. This hybrid system, combining ultrasound imaging and microfluidic techniques to ex vivo animal models, would be useful for monitoring the variations of biophysical properties induced by chemical agents. It can be used to understand the relation between biophysical parameters and CVDs.

Comparing serum levels of cardiac biomarkers in cancer patients receiving chemotherapy and subjects with chronic periodontitis

BACKGROUND

Chronic periodontitis (CP) is a chronic inflammation associated with elevations of several inflammatory and cardiac markers. Studies implicated CP as one of the etiologies in coronary heart disease (CHD). Cardiotoxicity is a major complication of anticancer drugs, including anthracyclines and 5-fluorouracil (5FU). The most severe cardiac complications are heart failure, arrhythmia and coronary heart disease (CHD). In this study, we compared the level of inflammatory factors and cardiac markers between chronic periodontitis patients and cancer patients receiving chemotherapy.

METHODS

108 blood samples of periodontally healthy subjects were obtained on random from Hong Kong Red Cross, and these represented the controlled population. Forty-four patients diagnosed with chronic periodontitis were recruited from the West China Hospital of Stomatology, Sichuan University. They have received scaling and root planning with mean pocket depths of 6.05 mm. Thirty breast cancer patients diagnosed with invasive ductal carcinoma from UNIMED Medical Institute, Hong Kong gave consent to participate in this study. They received 4 cycles of 500mg/m2 5-fluorouracil, 75 mg/m2 epirubicin and 500mg/m2 cyclophosphamide at a 3-week interval between each cycle. Peripheral venous blood from each group was taken for measurement of blood cells, inflammatory marker (P-selectin, high sensitvity C-reactive protein) and cardiac markers (troponin T; troponin I; N-terminal pro brain natriuretic peptide (Nt-proBNP) and Lactate dehydrogenase (LDH).

RESULTS

The lymphocyte count was higher (p < 0.05) in periodontitis patients than the other two groups, and more neutrophils (p < 0.05) were seen in cancer patients receiving chemotherapy. The two test groups demonstrated higher levels (p < 0.01) of inflammatory and cardiac markers than the control group.

CONCLUSIONS

The elevated cardiac markers found in periodontitis patients suggested that they may carry potential risks in developing cardiac lesions. Troponin T, troponin I, pro-BNP, LDH and high sensitvity C-reactive protein may be used as markers to monitor cardiac lesions in chronic inflammatory patients.

Increased plasma viscosity in young women with polycystic ovary syndrome using an oral contraceptive containing 35 μg ethinyl estradiol and 2 mg cyproterone acetate

OBJECTIVES

To investigate the influence of 6 months of treatment with an oral contraceptive (OC) containing 35 μ g ethinyl estradiol and 2 mg cyproterone acetate on plasma viscosity (PV) in young women with polycystic ovary syndrome (PCOS).

DESIGN

Patients with PCOS were assessed for PV before and after 6 months of treatment with an OC containing 35 μg ethinyl estradiol and 2 mg cyproterone acetate. PV was determined by a viscometer Type 53610/I SCHOTT-Instruments, Mainz at 37°C.

SETTINGS

Subjects were recruited from the Department of Obstetrics and Gynaecology, Division of Reproductive Endocrinology at the University Hospital of Patras, Greece.

PATIENTS

The study included 66 young women with PCOS.

MAIN OUTCOME MEASURES

PV.

RESULTS

In PCOS women as a whole, PV at baseline was 1.249 ± 0.049 mm(2)/s (n = 66). After 6 months of treatment with an OC containing 35 μg ethinyl estradiol and 2 mg cyproterone acetate, PV was increased to 1.268 ± 0.065 mm(2)/s (p = 0.038). The difference between PV before and after 6 months of treatment with an OC containing 35 μg ethinyl estradiol and 2 mg cyproterone acetate (Δviscosity) was 0.01864 ± 0.071452 mm(2)/s. ΔViscosity was related to ?fibrinogen (r = 0.270, p = 0.046), to Δhematocrit (r = 0.514, p = 0.09) and to Δtriglycerides (r = 0.292, p = 0.021).

CONCLUSION

Young women with PCOS presented an increased PV under OC treatment with 35 μg ethinyl estradiol and 2 mg cyproterone acetate.

Hemodilution therapy using automated erythrocytapheresis in central retinal vein occlusion: results of a multicenter randomized controlled study

BACKGROUND

Central retinal vein occlusion (CRVO) leads to poor visual outcome in most eyes. Abnormal hemorheology was suspected to play a major role in its pathogenesis. CRVO treatment is still a matter of debate but several studies have pointed out the efficacy of isovolumic hemodilution. The aim of this study was to assess the feasibility and efficacy of hemodilution using automated erythrocytapheresis in recent-onset CRVO.

METHODS

In this prospective randomized controlled multicenter study, 61 consecutive CRVO patients were enrolled when they met the following criteria: CRVO lasting for 3 weeks or less, visual acuity ranging from 20/200 to 20/32, age between 18 and 85 years, no diabetes, no uncontrolled systemic hypertension, no antiplatelet or anticoagulant therapy, hematocrit higher than 38%, and signed informed consent. Patients were randomly assigned to the hemodilution group (n = 31) or to the control group (n = 30). Hemodilution therapy consisted of one session of erythrocytapheresis on outpatient basis, followed by additional session(s) for 6 weeks if needed. Target hematocrit was 35%. Follow-up was 12 months.

RESULTS

No statistical differences in age, associated risk factors, or CRVO characteristics were observed at baseline between both groups. Mean visual acuity was equivalent to 20/80 in the hemodilution group and to 20/63 in the control group (non-significant difference). In the treated group, mean number of hemodilution sessions was 3.3 (range, 1 to 6), and no major side-effects occurred. At the 12-month follow-up visit, 64.5% of the hemodilution group had visual acuity of 20/40 or better compared to 40% of the control group (p = .048). Visual change was a gain of 1.7 ETDRS line in the hemodilution group versus a loss of 2.3 lines in the control group (p = .007). There was less conversion into an ischemic form in the hemodilution group (11%) than in the control group (50%, p = .004). Mean final retinal thickness was 289 μm in the hemodilution group versus 401 μm in the control group (p = .068).

CONCLUSIONS

This multicenter controlled randomized study demonstrated that automated erythrocytapheresis is a safe and effective tool for performing hemodilution and confirmed that hemodilution therapy can improve the final prognosis of CRVO when applied in the early phase of the disease.

Obesity and insulin resistance increase plasma viscosity in young women with polycystic ovary syndrome

OBJECTIVE

To investigate the plasma viscosity in young women with polycystic ovary syndrome (PCOS).

DESIGN

Patients with PCOS and healthy controls were assessed for plasma viscosity. The acquired data were tested for association with hyperandrogenemia, obesity and insulin resistance (IR) in patients with PCOS. Plasma viscosity was determined by a viscometer Type 53610/I SCHOTT-Instruments, Mainz at 37 degrees C.

PATIENTS

The study included 96 young women with PCOS and 72 healthy controls. Main outcome measures. Plasma viscosity and IR.

RESULTS

Plasma viscosity was 1.243 +/- 0.67 mm(2)/s in the control group and 1.252 +/- 0.82 in women with PCOS (p = 0.416). Using multiple regression analysis, total protein (B = 0.348, p = 0.005), area under curve for insulin (B = 0.320, p = 0.011) and BMI (B = 0.315, p = 0.013) were proven to be significantly correlated to plasma viscosity. Plasma viscosity was significantly increased in women with PCOS with IR compared to matched for age and BMI PCOS women without IR (1.300 +/- 0.055 vs. 1.231 +/- 0.049 mm(2)/s) (p = 0.004).

CONCLUSION

Young women with PCOS presented a plasma viscosity that was increased by obesity and IR. Therefore, clinical management of young overweight women with PCOS with IR should always include a serious reduction in body weight and the use of oral contraceptive treatment with cautious.

Effects of different resuscitation fluids on the rheologic behavior of red blood cells, blood viscosity and plasma viscosity in experimental hemorrhagic shock

BACKGROUND

Hemorrhagic shock is associated with severe rheological abnormalities. We hypothesized that in the setting of hemorrhagic shock, resuscitation can alter hemorheological characteristics dramatically, and different fluids cause different effects. The aim of this study was to investigate whether the type of fluid administered has an impact on hemorheological characteristics at the early stage of resuscitation in a rodent model of hemorrhagic shock.

METHODS

Animals were randomized into five groups: (1) sham hemorrhage (SHAM); (2) shock and sham resuscitation (SHOCK); (3) shock and resuscitation with normal saline 32 ml/kg (NS); (4) shock and resuscitation with 7.5% hypertonic saline 4 ml/kg (HS); (5) shock and resuscitation with 7.5% hypertonic saline/6% Dextran 70 4 ml/kg (HSD). Hemorheological characteristics were measured at 60 min after resuscitation.

RESULTS

Results showed that NS resuscitation deteriorated red blood cell (RBC) deformability compared with the SHOCK group. The HS group showed improved RBC deformability compared with the NS group, although the differences were not statistically significant. There were significant improvements of RBC deformability at all shear rates in the HSD group compared with the NS group. Whole blood and plasma viscosities decreased significantly in the SHOCK group compared with the SHAM group. At shear rates of 60 and 150 s(-1), the NS group decreased whole blood viscosity compared with the SHOCK group. The HSD group showed elevated plasma viscosity compared with the SHOCK, NS and HS groups.

CONCLUSION

These results suggested that at the early stage of hemorrhagic shock resuscitation, hypertonic-hyperoncotic resuscitation could improve RBC deformability compared with isotonic crystalloid resuscitation. Dextran 70 could elevate plasma viscosity to nearly baseline level. These effects of hypertonic-hyperoncotic resuscitation could be beneficial to maintain microcirculation.

Rapid and reversible alterations in thyroid function tests in dehydrated patients

Dehydration commonly leads to hypovolemia and hemoconcentration. Changes in thyroid hormone-binding proteins secondary to hemoconcentration profoundly affect total serum thyroid hormone concentrations. The authors sought to determine the acute effects of mild to moderate dehydration on thyroid hormone levels/thyroid function tests and its reversibility upon rehydration. Total thyroxine, total triiodothyronine, free thyroxine, and the free-thyroxine index decreased significantly after hydration, in parallel with the decrease in extra cellular fluid volume status markers. Triiodothyronine-resin uptake increased after hydration. Thyrotropin levels decreased by 8% after hydration. Hypovolemia leads to simultaneous alterations in extracellular fluid volume markers and thyroid hormone serum concentrations that reverse rapidly upon rehydration. This constitutes, by itself, a distinct and new clinical entity.

Social, behavioral, and metabolic determinants of plasma viscosity in the Whitehall II Study

PURPOSE

To examine the social, biological, and metabolic associations of plasma viscosity in a large epidemiological study.

METHODS

Plasma viscosity was measured from 4548 men and 1837 women that took part in the fifth phase of the Whitehall II Study (1997-1999). Employment grade was used as a measure of social position.

RESULTS

A strong inverse relation between employment grade and plasma viscosity was evident (p < 0.0001). This employment grade gradient was apparent overall, and among non-smokers and when participants with poor health were removed from the analyses. Plasma viscosity was associated with a number of biological factors that are themselves socially determined, including fibrinogen (p < 0.001), triglycerides (p < 0.001), fasting insulin (p < 0.001), and height (p < 0.001). Associations with smoking and alcohol intake were apparent in women. In men a U-shaped curve was apparent such that those drinking between 11 and 24 units/week had the lowest plasma viscosity. Alcohol intake, physical activity, and smoking explained 18% of the grade gradient in men and 40% in women while the biological factors examined accounted for 35% in men and 40% in women.

CONCLUSION

There is a grade gradient in plasma viscosity which was not fully explained by health related behaviors or measured risk factors for CHD. These data suggest that additional factors that contribute to the rheological properties of plasma may contribute to the explanation for social inequalities in cardiovascular disease.

Endothelial dysfunction in peripheral arterial disease is related to increase in plasma markers of inflammation and severity of peripheral circulatory impairment but not to classic risk factors and atherosclerotic burden

OBJECTIVE

We undertook this study to evaluate in patients with peripheral arterial disease (PAD) the relationship of endothelial dysfunction, which is directly related to progression and clinical complications of atherosclerosis, with variables including classic risk factors, inflammation, severity of peripheral circulatory impairment, and atherosclerotic burden.

METHODS

This cross-sectional study included outpatients seen in an academic angiologic unit. Eighty-eight consecutive patients with PAD (ankle/brachial index [ABI] < 0.90) were studied. The control group consisted of 30 age-matched and sex-matched healthy subjects. Main outcome measures were endothelial function in the form of brachial artery flow-mediated dilation (FMD), plasma levels of C-reactive protein (CRP) and fibrinogen, severity of PAD according to ABI, and atherosclerotic burden, ie, atherosclerosis in one leg or in two or more other sites.

RESULTS

Compared with patients with FMD greater than 6.2% (ie, 5th percentile of FMD in control subjects), patients with FMD less than 6.2% had a similar prevalence of classic risk factors but higher median levels of CRP (1.6 vs 6.0 mg/L; P <.01) and fibrinogen (200 vs 374 mg/dL; P <.01). The two inflammatory markers were negatively correlated with FMD (P <.01). ABI was higher in patients with FMD greater than 6.2% than in those with worse endothelial function (0.72 +/- 0.15 vs 0.62 +/- 16; P <.01); there was no difference with respect to atherosclerotic burden. Multivariate analysis showed that the association of CRP, fibrinogen, and ABI with FMD less than 6.2% was unrelated to classic risk factors. In a second model, which included CRP, fibrinogen, and ABI, all three variables were independently related to FMD less than 6.2%.

CONCLUSION

Inflammation and severity of circulatory impairment are implicated in the pathophysiology of dysfunctional endothelium in PAD.

Blood rheology in men with essential hypertension and capillary rarefaction

The pathophysiological significance of hyperviscosity and capillary rarefaction in untreated essential hypertension is unknown. Fifty untreated hypertensive men with capillary rarefaction (intravital capillaroscopy) and 20 age- and sex-matched normotensive controls underwent full haemorheological profiling (blood viscosity at high and low shear, haematocrit, platelet and leukocyte counts, fibrinogen and total protein concentrations, P-selectin levels, erythrocyte and leukocyte filterability rates and erythrocyte deformability and aggregation indexes). Subjects with skin capillary density below the group median had younger age, higher diastolic pressure, higher blood viscosity at low shear, higher P-selectin levels, higher erythrocyte and leukocyte filterability rates, and higher erythrocyte aggregation indexes (all P < 0.01). In contrast, patients with greater skin capillary density had a greater plasma viscosity (P < 0.05). The conclusions were that in untreated hypertensive men, capillary rarefaction and hyperviscosity are associated to an increased diastolic blood pressure and to an adverse haemorheological profile.

Coronary artery disease and periodontal disease: is there a link?

BACKGROUND

Cardiovascular disease is the number one killer worldwide. The so-called classic risk factors of coronary heart disease do not account for all of its clinical and epidemiological features. Recent evidence suggests that certain infections, among them dental infections and in particular periodontal disease, are involved in the pathogenesis of coronary artery disease.

AIM

To evaluate the association between periodontal disease and coronary artery disease.

PATIENTS AND METHODS

Fifty patients referred for diagnostic coronary angiography were assessed for periodontal disease. All patients underwent a thorough physical examination, routine laboratory testing, cardiac evaluation and dental examination which included pantomography x-ray evaluation.

RESULTS

Pantomography x-rays and coronary angiograms of the participants were scored blindly by a dentist and cardiologists respectively. The association between periodontal disease and coronary atheromatosis remained significant after adjustment for age, smoking, blood lipids, body mass index, hypertension and the presence of diabetes.

IMPLICATIONS

Periodontal disease was still significantly associated after all the known risk factors were accounted for. The implication here is that periodontal disease could be a potential risk factor for heart disease by predisposing the individual to chronic low-grade infections. If so, then dental health becomes an important parameter for medical health.

Preoperative predictors of the need for allogeneic blood transfusion in lung cancer surgery

BACKGROUND

The use of blood-saving techniques in elective surgery can produce a favorable cost-benefit ratio only when there is a reasonable likelihood that transfusion will be required. To apply a targeted blood-sparing technique in lung cancer surgery, the patient's preoperative characteristics that predict the use of allogeneic blood transfusion (ABT) in this practice were investigated.

STUDY DESIGN AND METHODS

One hundred seventy-three consecutive patients who underwent primary lung cancer surgery were included in this retrospective study. Clinical and epidemiologic variables, lung tumor extension (TNM staging), and surgery type were analyzed by logistic regression to discover the preoperative predictors of ABT.

RESULTS

Thirty patients, 17.3 percent of all who underwent surgery and 19.9 percent of those who underwent resolvent surgery, received ABT. Excluding a patient who needed 18 units of RBCs, the number of ABT units required by transfused patients was 1. 93 +/- 0.88 (mean +/- SD). Extensive surgery, patient's age (< or =64 years), and elevated erythrocyte sedimentation rate (>45 mm/hour) were the preoperative variables that influenced the need for ABT. The definitive predictive model was able to recognize 82.3 percent of patients who received ABT and 95.6 percent of those who did not.

CONCLUSION

A predictive model can preoperatively identify patients at risk for needing ABT in lung cancer surgery. The model could be utilized to tailor blood-sparing intervention programs.

Does hypertension confer a hypercoagulable state?

Although the blood vessels are exposed to high pressures in hypertension, the main complications of hypertension (stroke and myocardial infarction) are paradoxically thrombotic rather than haemorrhagic. In keeping with Virchow's triad, patients with hypertension do demonstrate abnormalities of vessel wall (endothelial dysfunction or damage), blood constituents (abnormal levels of haemostatic factors, platelet activation and fibrinolysis) and blood flow (rheology and flow reserve), suggesting that hypertension does confer a prothrombotic or hypercoagulable state. These abnormalities appear to be related to target organ damage and long-term prognosis and are altered by treatment. The observation that satisfactory blood pressure reduction with non-drug intervention and with various classes of antihypertensive drugs does not lead to an equal reduction in heart attacks and strokes may be due in part to unfavourable effects on the hypercoagulable state in hypertension. Antihypertensive agents with particular benefits in reducing this hypercoagulable state would be likely to have additional advantages in reducing the occurrence of stroke and other thromboembolic events.

Blood viscosity and elevated carotid intima-media thickness in men and women: the Edinburgh Artery Study

BACKGROUND

Several hemostatic and rheological factors have been associated with incident cardiovascular events. However, there have been no reports on the relationship of rheological factors with early atherosclerosis and very few on hemostatic factors. We therefore studied the relationship between these factors and carotid intima-media thickness (IMT).

METHODS AND RESULTS

The Edinburgh Artery Study measured fibrinogen, tissue plasminogen activator (tPA), fibrin D-dimer, von Willebrand factor (vWF), blood and plasma viscosities, and hematocrit as part of its baseline examination during 1988-1989. At the 5-year follow-up, valid measurements of IMT had been recorded in 1106 men and women 60 to 80 years old. In men, blood viscosity (P< or =.001) and its major determinants, plasma viscosity, fibrinogen (both P< or =.01), and hematocrit (P< or =.05), were all linearly related to IMT. Furthermore, blood viscosity, fibrinogen (both P< or =.01), and plasma viscosity (P< or =.05) remained significantly associated on multivariate analysis. Correcting blood viscosity to a standard hematocrit of 45% had little effect on its association. In men, there was a significantly increased risk of having an IMT above versus below the upper quartile of its distribution (1.05 mm) for SD increases in blood viscosity (P< or =.01), fibrinogen, corrected blood viscosity, and plasma viscosity (all P< or =.05). With the exception of plasma viscosity, these risks were unaffected by adjustment for other common cardiovascular risk factors. No significant associations were found between any of the hemorheological factors and IMT in women or for tPA, fibrin D-dimer, or vWF in either sex.

CONCLUSIONS

These findings suggest that in men, blood viscosity and its major determinants are associated not only with incident cardiovascular events but also with the early stages of atherosclerosis. This may be one explanation for the link between rheological factors and events.

Effect of hemodialysis and recombinant human erythropoietin on determinants of blood viscosity

Blood viscosity (hemorheology) is a major determinant of the rate of blood flow, and increases in viscosity are known to be involved in the etiology of vascular diseases. This placebo-controlled study investigated the independent and combined effects of hemodialysis and recombinant human erythropoietin (rHuEpo) on determinants of blood viscosity in patients with chronic renal failure and related any changes to the normal physiological range. Hemodialysis patients were shown to have a high incidence of rheological abnormalities although the degree of anemia associated with chronic renal failure compensated for these changes. The main effect of both hemodialysis and rHuEPO treatment was an increase in hematocrit associated with a rise in blood viscosity and inconsistent changes in red blood cell (RBC) deformability. The rise in viscosity was significant only following rHuEPO treatment. Hemodialysis-induced increases in blood and plasma viscosity correlated strongly with the degree of hemoconcentration. Although hemodialysis patients have inherent hemorheological abnormalities, correction of renal anemia with rHuEPO to a hematocrit level of < 0.35 in conjunction with dialysis-induced hemoconcentration did not result in adversely high blood viscosity levels in any patient.

The role of echocardiography in the evaluation of cardiac source of embolism: left atrial spontaneous echo contrast

Left atrial (LA) spontaneous echo contrast, also known as "smoke," is a frequent transesophageal echocardiographic finding characterized by swirling, smokelike echoes in the LA cavity or appendage. LA smoke is associated with conditions favoring stasis of LA blood, including atrial fibrillation, mitral stenosis, the absence of mitral regurgitation, and LA enlargement. LA spontaneous echo contrast is a marker of previous embolic events in patients with atrial fibrillation, mitral stenosis, or mitral valve replacement. Most LA thrombi are accompanied by smoke. Recent studies show that LA spontaneous echo contrast is also associated with increased fibrinogen, hematocrit, and blood viscosity, indicating a relatively hypercoagulable state in addition to stasis. These findings suggest that LA spontaneous echo contrast is a manifestation of erythrocyte aggregation, and that hematologic factors may contribute to the association between spontaneous echo contrast and thromboembolism.

Blood viscosity, fibrinogen, and activation of coagulation and leukocytes in peripheral arterial disease and the normal population in the Edinburgh Artery Study

BACKGROUND

Increased blood and plasma viscosity, hematocrit, fibrinogen, and activation of coagulation and leukocytes have been reported in patients with claudication; however, their associations with symptomatic and asymptomatic peripheral arterial disease have not been reported in an epidemiological study.

METHODS AND RESULTS

Blood and plasma viscosity, hematocrit, fibrinogen, urinary fibrinopeptide A, plasma leukocyte elastase, and uric acid were measured in a random sample of 1,581 men and women aged 55-74 years in Edinburgh, Scotland, and related to peripheral arterial stenosis (ankle-brachial systolic pressure index, ABPI) and to lower limb ischemia (intermittent claudication and reactive hyperemia test). Each variable (except fibrinopeptide A) was significantly related to prevalent symptomatic and asymptomatic peripheral arterial disease. On multivariate analysis, blood viscosity (p < 0.05) and fibrinogen (p < 0.01) were independently associated with peripheral arterial narrowing (ABPI); a positive interaction was found between fibrinogen and smoking in the association with ABPI. Plasma viscosity was associated with claudication in the presence of a given degree of arterial narrowing (odds ratio of claudication in top quintile compared with bottom quintile of plasma viscosity, 3.35; 95% CI, 1.32, 8.51). Leukocyte elastase and uric acid were each associated with reactive hyperemia independently of arterial narrowing (p < 0.01).

CONCLUSIONS

Blood rheological factors and leukocyte activation as well as arterial narrowing are associated with lower limb ischemia in the general population and may be implicated in its pathogenesis.

Dental disease, fibrinogen and white cell count; links with myocardial infarction?

Plasma fibrinogen and white blood cell count were compared in fifty patients aged 25-50 years with periodontal disease and in fifty age-matched controls with relatively healthy periodontal tissues. Patients had significantly higher levels of fibrinogen and white cell count, and dental indices correlated significantly with these two cardiovascular risk factors on multivariate analyses. We suggest that inflammatory dental disease may be a determinant of fibrinogen level and white cell count in the general population, and that fibrinogen and white cell count may be two mediators of the link between dental disease and myocardial infarction.

Blood rheology during bacterial infection in the elderly and early middle-aged

The aim of this study was to ascertain if the hemorheological profiles in 35 elderly and 20 young to middle-aged patients returned to normal after bacterial infection. Erythrocyte sedimentation rates, fibrinogen levels, plasma viscosity, hematocrit, white blood cell count and filterability rates (through 5 mu diameter pore filters, using a low shear positive pressure Nuclepore filtration system) of red blood cells and unfractionated leucocytes were determined at the onset of acute bacterial infection, after 3 weeks at full clinical recovery, and again 2 weeks later at the end of convalescence. Our data confirm that rheological impairments exist at the onset of bacterial infection, and persist up to clinical recovery. At the end of convalescence the unfractionated leucocyte filterability rate was still significantly higher in the elderly patients, compared not only to our normal standard, but also to average values in the younger group.

Efficacy of low-molecular-weight heparin in the management of intermittent claudication

Treating chronic arterial occlusive disease with heparin is controversial because of the risks associated with long-term anticoagulant therapy. Low molecular weight (LMW) heparin (mw about 5000 Dalton), which selectively inhibits the Xa factor with minimal risk of hemorrhage, seems to offer new possibilities in the prevention and treatment of both venous and acute arterial thromboembolism. Therefore, 44 patients with intermittent claudication were recruited to a randomized, double-blind, controlled study. Twenty-two were treated for six months with a single daily subcutaneous dose (15,000 UaXa) of LMW heparin and 22 with placebo administered in the same way over the same period of time. After six months, LMW heparin treatment not only improved walking capacity (by lengthening the pain-free walking time by 25%) but also significantly modified the hemorrheologic pattern (by reducing fibrinogen concentrations and whole blood viscosity at low shear rates). LMW heparin also exerted an antithrombotic and profibrinolytic effect by significantly increasing both the anti-Xa factor and plasminogen activity without markedly modifying activated partial thromboplastin time (+20%). No LMW heparin-treated patient hemorrhaged or reported other noteworthy side effects. These results suggest LMW heparin might be a useful drug in the long-term treatment of chronic arterial occlusive disease of the limbs.

Hemorheologic abnormalities in patients with human immunodeficiency virus infection and ophthalmic microvasculopathy

The severity of conjunctival microvascular changes and the presence of cotton-wool spots were compared to factors that may affect blood flow (hematocrit level, red cell aggregation, fibrinogen level, plasma viscosity, circulating immune complexes, and quantitative immunoglobulin levels) in 22 human immunodeficiency virus-infected individuals. The severity of conjunctival disease was associated with increased zeta sedimentation ratios (a measure of red cell aggregation) and fibrinogen levels. The presence of cotton-wool spots was also associated with higher fibrinogen levels. Plasma viscosity and quantitative IgG levels were above normal levels in most patients, although a relationship to disease severity was not established. Altered blood flow may contribute to vascular damage and ocular ischemic lesions in patients with human immunodeficiency virus infection.

Stable angina pectoris and controlled ischemia: what causes the abnormalities in whole blood filterability?

The determinants of the altered whole blood filterability observed during coronary ischemia are still under discussion. Since no studies have been carried out to date on what exactly causes these alterations during the early stages of controlled ischemia in coronary heart disease, a model was set up using a bicycle ergometer test (with a 25 W increase every 2 minutes). Blood samples were taken from 48 stable angina pectoris patients and from a group of 28 matched controls before and immediately after exercise and 8 minutes later. Plasma viscosity, the filterability (through 5 microns diameter pore filters) of whole blood, erythrocytes, and polymorphonuclear and mononuclear leukocytes (separated by density gradient) were monitored. Alterations in whole blood filterability could be linked only to an impairment in polymorphonuclear cell filterability in those stable angina pectoris patients who reported chest pain and/or whose ST segment depression was greater than or equal to 2 mm.

Association of hypertension with blood viscosity in diabetes

Plasma and whole blood viscosity and its determinants were measured in 86 diabetic patients (29 hypertensive and 57 normotensive) and compared with 52 non-diabetic control subjects to assess whether hypertension has an additive and adverse effect on blood viscosity. Whole blood viscosity (corrected for haematocrit), at high and low shear rates (95 and 0.95 s-1), was significantly higher in both Type 1 (5.1 +/- 0.5 (+/- SD), 19.8 +/- 2.9) and Type 2 (5.2 +/- 0.3, 21.1 +/- 2.0) diabetic patients compared with control subjects (4.9 +/- 0.6, 17.4 +/- 2.6 mPa s, p less than 0.01). Corrected whole blood viscosity at high shear rate was significantly higher in hypertensive than in normotensive Type 2 diabetic patients (5.5 +/- 0.4 vs 5.2 +/- 0.3 mPa s, p less than 0.01). Plasma viscosity was significantly higher in diabetic patients compared with control subjects (1.4 +/- 0.1 vs 1.3 +/- 0.1 mPa s, p less than 0.01), but there was no difference between hypertensive and normotensive diabetic patients (1.4 +/- 0.1 vs 1.4 +/- 0.2 mPa s). Fibrinogen levels were similar in all the groups.