Can we boost screening for peripheral arterial disease?

 

Despite the high prevalence of peripheral artery disease (PAD), the diagnosis is often delayed. The delayed diagnosis is due in part to comorbidities which can mask PAD symptoms, and in large part to the low use of conventional diagnostic tools. For PAD diagnostics, the guidelines recommend Doppler-based ankle-brachial index (ABI). The method is time consuming and requires skills. The toe pressure measurement which helps to eliminate the falsely elevated ankle pressures due to mediasclerosis is an almost neglected method for screening. In recent years, automatic, oscillometric four-limb blood pressure monitors have become available that provide data within minutes. We aimed to compare an automatic four limb blood pressure monitor with devices regularly used in our department.

Methods

Blood pressure was measured in 92 individuals (mean age 65±14 years) using a Doppler device (Hadeco) and a conventional manual sphygmomanometer on all four limbs, as well as an automatic, four-limb pressure monitor (BOSO ABI system-100 PWV) which also measured pulse wave velocity (PWV). Toe pressure was measured with a laser Doppler fluxmeter (Periflux 5000) and a photophlethysmography based toe pressure monitor (Systoe). Patients without known PAD but with at least one abnormal test result underwent a vascular imaging including ultrasound, CT or digital subtraction angiography. Among the 92 individuals there were patients with confirmed PAD, persons at high or very high cardiovascular risk, patients with non-ischaemic cardial diseases and healthy volunteers.

Results

ABI values of the posterior tibial artery at the corresponding side measured by Doppler and BOSO showed a strong correlation with each other (Pearson's r: 0.8 and 0.7), while the Doppler ABI values of the dorsal pedal artery showed a moderate or weak correlation with BOSO ABI values (r: 0.63 and 0.27). The toe pressure measured by laser Doppler and Systoe did not differ significantly. The ROC curve analysis of the Periflux TBI values supported 0.6 as a cut-off level (91.6% sensitivity, 84% specificity). Of the 52 individuals with high or very high cardiovascular risk, 15 with Doppler, 12 with BOSO and 29 with Periflux could be considered as abnormal, the vascular imaging confirmed PAD in 12 of them. Doppler ABI was abnormal in 96%, BOSO ABI in 69%, BOSO ABI combined with PWV in 92%, Periflux and Systoe toe brachial index (TBI) in 100–100% in 72 limbs with confirmed PAD. In control subjects, ABI, TBI, and PWV were normal; in subjects with high or very high risk, PWV was 58% abnormal, in confirmed PAD, 85%. All patients with abnormal PWV showed atherosclerotic lesions by the vascular imaging.

Summary

For detection of PAD, the measurement of TBI had the highest sensitivity. PAD screening of a large population may be possible using automatic four limb blood pressure monitors. By combining with additional features (e.g. PWV) the detection ratio can be improved to the level of the Doppler ABI method.

Funding Acknowledgement

Type of funding sources: None.

The role of hemorheological factors in cardiovascular medicine

Cardiovascular diseases (CVD) are the most frequent cause of death throughout the world. The coronary vessel system is a special part of the circulation since there is a continuous change in blood flow, perfusion pressure and shear rate during each cardiac cycle. It is also the place of the narrowest capillaries in the human body, therefore the role of rheological alterations may be of greater importance than in the other parts of the circulatory system. During the past decades, our group has investigated hemorheological parameters (HP) in over 1,000 patients diagnosed with various forms of ischemic heart disease (IHD). In one prospective study, we measured the HP of patients with acute coronary syndrome (ACS). On admission, all examined variables were significantly worse than those of control subjects. During the hospital phase, some of the HP showed further deterioration, and HP remained in the pathologic range during the follow-up period. In another study, we showed that HP are in close correlation with the severity of coronary artery disease. In patients treated with percutaneous coronary intervention, changes in HP were very similar to those observed in subjects with ACS. In a recent study, we analyzed HP in patients undergoing CABG surgery. Our data suggest a hemorheological advantage of off-pump surgery. In another study low Hct/WBV ratio can be regarded as a risk factor of cardiac death in IHD. Our data indicate that rheological parameters are significantly altered in patients with IHD: the extent of the alterations is in excellent correlation with the clinical severity of the disease. Our findings prove that HP play a critical role in the pathogenesis of myocardial ischemia. In recent in vitro and in vivo studies we have investigated the effects of red wine on hemorheological parameters. Our results show that moderate red wine consumption has beneficial effects on hemorheological parameters which may contribute to the French paradox.

The influence of on-pump and off-pump coronary artery bypass grafting on hemorheological parameters

Conditions during coronary artery bypass grafting (CABG) performed on beating heart (off-pump) are more physiological than using extracorporeal perfusion (on-pump). The present study aims to examine the hemorheological aspects of the two techniques. Blood samples were taken from patients undergoing on-pump (n = 25) and off-pump (n = 22) CABG, upon arrival to the operating theatre, after 20 and 40 minutes during the operation, after closing the thorax, on the 1st and 2nd postoperative days, and during the 2nd and 6th month control check-ups. Hematocrit (Hct), plasma and whole blood viscosity (PV, WBV; Hevimet 40 capillary viscometer), red blood cell (RBC) aggregation (Myrenne RBC aggregometer, LORCA) and deformability (LORCA, Carat FT-1 filtrometer), and platelet aggregation (Carat TX4 aggregometer) were determined. The morphology of red blood cells was investigated by scanning electron microscopy (SEM). Hct, PV, WBV and RBC aggregation decreased significantly during the early phase of the surgery, they started to recover during the postoperative period, and reached the baseline values by the 2nd and 6th month control check-ups. These parameters were significantly lower in samples taken after 20 and 40 minutes in the on-pump group. SEM showed rather damaged and malformed cells in case of on-pump surgery. Ektacytometry showed no significant difference, but RBC deformability was impaired during on-pump surgery when measured by filtrometry. The decrease in platelet aggregation was more pronounced by the end of surgery in case of on-pump technique. During CABG rheological parameters change less when using the off-pump method, and mechanical damage of RBCs are also smaller. The off-pump technique seems to be favorable from a hemorhelogical point of view.

Reviewing data reduction methods for ektacytometry

Ektacytometry quantifies erythrocyte deformability by measuring the elongation of suspended red blood cells subjected to a range of shear stresses. Raw shear stress-elongation index plots are difficult to interpret and thus data reduction methods characterizing the relationship using few parameters without loss of information and good reproducibility are essential, especially for the clinician. Two such curve fitting formulas, used widely in the literature for this purpose, are reviewed herein. The Lineweaver-Burke method overestimates maximal deformability if shear stresses below 1 Pa are applied. A modified version of the formula estimates maximal deformation more accurately but gives little weight to data at low shear stresses. Neither method is accurate if negative elongation indices are present (artifact phenomenon when measurement is performed from high to low shear stresses). The Streekstra-Bronkhorst method provides efficient data reduction though the theoretical background of the formula is incorrect. The parameters have expressive meaning; however, both maximal and minimal deformations are slightly underestimated. Moreover, parameters are biased according to the range of measured shear stresses.

The effect of aspirin on hemorheological parameters of patients with diabetic retinopathy

Hemorheological factors play an important role in the pathogenesis of severe complications of diabetes. The diabetic retinopathy is the leading cause of blindness in patients aged 20-65 years. In our study we investigated the effect of aspirin on the hemorheological parameters in patients with different diabetic retinopathies. Hemorheological parameters (hematocrit, fibrinogen, plasma and whole blood viscosity, red blood cell aggregation) of diabetic patients with non-proliferative (n=14, mean age: 66 years) and proliferative retinopathy (n=8, mean age: 48 years) were measured. The results between the two groups were compared: twelve patients were taking aspirin (group A), while ten patients were not (group B).Hematocrit, fibrinogen, plasma and whole blood viscosity were significantly higher (p < 0.05-0.001) in patients with diabetic retinopathy who did not take aspirin than in those who took. No significant difference was observed in red blood cell aggregation parameters between the two groups. We could not find any significant difference in the measured parameters between patients with non-proliferative and proliferative diabetic retinopathy. According to our results, all the measured hemorheological parameters were in the pathological range, although aspirin treatment could decrease these factors and thus may help to prevent the progression of severe diabetic retinopathy and perhaps blindness.

Low hematocrit per blood viscosity ratio as a mortality risk factor in coronary heart disease

Increased blood viscosity has not been associated with mortality risk in coronary heart disease (CHD). We aimed to investigate the predictive power of hematocrit per blood viscosity (Hct/BV) ratio as a marker of rheological oxygen carrying capacity of the blood to assess mortality risk of CHD. Elective coronary angiography was performed and CHD was proved in 109 patients in 1996 and 1997. In 78 cases (72%) complete follow up information was obtained in February 2006. During the follow up time (mean 8.9 years) 10 patients died due to cardiac cause (group C). Two patients died due to non-cardiac cause and 66 were still alive at the end of the follow up period (group NC, n=68). Mean hematocrit per blood viscosity (Hct/BV) ratio was significantly lower in group C comparing to NC (87+/-5; 93+/-9 Pa(-1)s(-1), SD, respectively, p=0.022). Other factors (body mass index, serum cholesterol, fibrinogen, hematocrit, plasma and blood viscosity, cardiac index, left ventricular ejection fraction) provided no statistical differences. Kaplan-Meier survival analysis showed only the impact of fibrinogen and Hct/BV ratio on cardiac mortality (p=0.029 and 0.009, respectively). Receiver operating characteristic curves proved only Hct/BV ratio to be able to differentiate between groups (area under curve: 0.716, p=0.028). Hct/BV ratio showed significant negative correlation with the frequency of hospital admissions (r=-0.377, p=0.03). Low Hct/BV ratio can be regarded as a risk factor of cardiac death in CHD.

Gender differences in hemorheological parameters of coronary artery disease patients

Plasma fibrinogen concentration, plasma and whole blood viscosity (WBV) are independent risk factors of coronary artery disease (CAD). Fibrinogen seems to be a relatively stronger risk factor for women than for men, but men are more endangered by higher hematocrit (Hct) and WBV than women are. We have previously reported that a theoretically optimal Hct value can be determined using Hct/WBV ratio in healthy subjects, hyperlipidemic and Raynaud's disease patients. Our aim was to examine whether Hct/WBV ratio is differently correlated with Hct in men and women with proven CAD. In a retrospective study we analysed the hemorheological data of 162 CAD outpatients (107 men and 55 women). Coronary angiography, echocardiography and impedance cardiography were performed. Hemorheological parameters (Hct, fibrinogen level, plasma viscosity, WBV), blood picture, serum lipid concentrations were determined and Hct/WBV ratio was calculated. Mean ages of male and female patients were similar (54.9 and 55.4 years, respectively), but men had significantly higher coronary angiography score than women. Mean left ventricular ejection fraction, stroke volume index and cardiac index showed no significant differences in men and women. Similarly, lipid concentrations, fibrinogen levels and plasma viscosities demonstrated no statistical differences. However, Hct, WBV and Hct/WBV ratios were significantly higher in male than in female patients (p < 0.00001; p < 0.00001 and p < 0.005, respectively). The most striking gender difference was found in the correlation between Hct/WBV ratio and cardiac index. Men older than 56 years showed negative, women positive correlation (r = -0.485, p = 0.01; r = 0.468, p = 0.006, respectively). This study demonstrates that Hct/WBV ratio as a rheological oxygen carrying capacity parameter is positively correlated with the cardiac index as it can be expected. However, the correlation is negative in elder men indicating an unhealthy relation between hemodynamic and hemorheologic parameters.

Erythrocyte transport efficacy of human blood: a rheological point of view

BACKGROUND

Large-scale epidemiological studies have demonstrated that both anaemia and polycytaemia are independent cardiovascular risk factors. This was substantiated by the Framingham study, which demonstrated a U-shaped relation between haemoglobin concentration and mortality. It was previously noted that delineating the corresponding haematocrit/blood viscosity ratios in the function of haematocrit provided a distribution of an inverted U-shaped curve. The peak appeared physiologically important because it denotes a healthy balance between a relatively high oxygen binding capacity and a moderately low blood viscosity. It was the aim of this study to examine the mathematical relationship between the haematocrit and haematocrit/blood viscosity ratio.

MATERIALS AND METHODS

In a retrospective study, the haemorheological data of 32 healthy controls, 52 outpatients with hyperlipidaemia and 120 outpatients with Raynaud's disease were analyzed. Whole blood viscosity was measured with Hevimet 40 capillary viscometer at 37.0 degrees C and at shear rates of 10 s(-1), 90 s(-1) and 200 s(-1).

RESULTS

Haematocrit/blood viscosity ratios in the function of haematocrit values showed a Gaussian association in the healthy subjects, hyperlipidaemic and Raynaud's disease outpatient groups. Peak values (i.e. the rheologically optimal haematocrit) were shear-rate and group dependent and were found at 44.3%, 43.5% and 38.3% in controls, hyperlipidaemic and Raynaud's disease patients, respectively, at a shear rate of 90 s(-1).

CONCLUSIONS

This is one of the first reports in which a theoretically optimal haematocrit value was determined using the haematocrit/blood viscosity ratio. Further studies are needed to examine the potential clinical usefulness of this approach.

Hemorheological disturbances in patients with chronic cerebrovascular diseases

Hemorheological disturbances may occur in more than 40% of patients with ischemic cerebrovascular diseases. In this study the changes of rheological factors--hematocrit, plasma fibrinogen concentration, whole blood and plasma viscosity, red blood cell aggregation and deformability were investigated in 297 patients (173 males, 124 females, mean age 60 +/- 11 years) with transient ischemic attack or chronic phase (> 3 months after onset) ischemic stroke, and in 73 healthy volunteers (35 males, 38 females, mean age 38 +/- 7 years). Hematocrit, plasma and whole blood viscosity were significantly (p < 0.0001) elevated in cerebrovascular patients compared to controls. Plasma fibrinogen concentration (p < 0.001), red blood cell aggregation (p < 0.05) and deformability (p < 0.01) were also impaired in stroke patients. Hemorheological disturbances were dominant in stroke patients with diabetes, hyperlipidemia and smoking habits. Hematocrit, plasma viscosity and red blood cell aggregation showed a significant (p < 0.025-0.001) correlation with the severity of carotid artery stenosis. We could not find any characteristic distribution of rheological parameters among the three subtypes of brain ischemia. Our results show that all of the measured rheological parameters are significantly impaired in chronic ischemic cerebrovascular disorders, especially in diabetic, smoking and alcoholic patients. They correlate with the severity of the carotid artery stenosis, but there is no association with the type of ischemic stroke.

Follow-up of hemorheological parameters and platelet aggregation in patients with acute coronary syndromes

Pathologic hemorheological parameters and increased platelet aggregation in association with other risk factors significantly increase the possibility of the development of myocardial ischemia. Hemorheological parameters and platelet aggregation were investigated in 157 patients (mean age: 65+/-12 years) with acute coronary syndromes and in 68 healthy subjects (mean age: 36+/-6 years). Plasma fibrinogen, plasma and whole blood viscosity, red blood cell aggregation and filterability and platelet aggregation were measured in the hospital phase (after admission, on 2nd and 6th days) and monitored after discharge (at 1, 6 and 12 months). After admission all these parameters were significantly higher in patients than in control subjects (p<0.01) and almost all of them remained in the pathologic range at discharge. Some of the rheologic parameters showed a slight improvement after 1 month, but hematocrit and whole blood viscosity were higher than those after admission and of control subjects (p<0.05). After 6 and 12 months these parameters showed a small, but significant increase. Pathologically altered hemorheological parameters could be observed in patients with classical cardiovascular risk factors and significant improvement was found after elimination of them. Antiplatelet therapy was efficient in about half of the treated patients after admission; and despite a significant improvement, the proportion of ineffectively treated patients was still considerable during the follow-up. Our results support the role of abnormal hemorheological parameters in the development of myocardial ischemia and draw attention to the rheologic risk of these patients. The results of platelet aggregation measurements show the insufficiency of antiplatelet therapy at some cases and confirm the importance of guided secondary prevention.

Hemorheological alterations in patients with diabetic retinopathy

Hemorheological factors play an important role in the pathogenesis of different cardiovascular diseases. Diabetes mellitus resulting in micro- and macroangiopathies is one of the major risk factors for cardiovascular diseases. In our present study the hemorheological parameters (hematocrit, plasma fibrinogen level, plasma and whole blood viscosity, red blood cell aggregation) of 30 diabetic patients (mean age: 57 +/- 12 years) and 30 healthy volunteers (mean age: 31 +/- 10 years) were examined. The fundus appearance of patients showed diabetic retinopathy; non-proliferative stage in 22 cases, preproliferative or proliferative stage in 8 cases. The measured hemorheological parameters of the examined patients were in the pathological range and were significantly higher than those of healthy volunteers (hematocrit: p < 0.01; plasma fibrinogen: p < 0.001; plasma viscosity: p < 0.01; whole blood viscosity: p < 0.001; red blood cell aggregation: p < 0.01). In our study there was not significant difference in the hemorheologic variables of patients with different stages of retinopathy. Our results propose the importance of hemorheologic factors in the development of diabetic microangiopathy.

Scavenger effect of experimental and clinically used cardiovascular drugs

Oxygen free radicals play an important role in several physiologic and pathophysiologic processes. In pathophysiologic circumstances they can modify and damage biologic systems. Their functional properties (exposed to high oxygen tension) place red blood cells among the most susceptible cells to the harmful effect of free radicals. Because oxygen free radicals are involved in a wide range of diseases, scavenging these radicals should be an important therapeutic approach. In this study the antioxidant capacities of experimental and clinically used cardiovascular drugs were investigated. Phenazine methosulfate was used to generate free radicals and thus harden red blood cells. Filtration technique and potassium leaking were used to detect the scavenging effect of the examined drugs. The experimental drug H-2545 provided 43% protection against phenazine methosulfate-induced changes in red blood cell filterability (p < 0.001). Although some of the examined, clinically used cardiovascular drugs (carvedilol, metoprolol, verapamil, trimetazidine) also showed significant (p < 0.05) antioxidant effect, they were less efficient than H-2545. The scavenger effect of this novel drug exceeded the antioxidant properties of vitamin E. Modification of mexiletine with a pyrroline ring significantly improved its antioxidant capacity, suggesting that this molecular segment is responsible for the antioxidant effect.

The effect of carvedilol on enhanced ADP-ribosylation and red blood cell membrane damage caused by free radicals

OBJECTIVE

Previous studies have reported that the beta and alpha adrenoceptor blocker carvedilol has unique protective effects on free radical-induced myocardial injury. The aim of this study was to examine how carvedilol regulates reactive-oxygen-species-mediated signaling and decreases red blood cell membrane damage in heart perfusion and in a rheological model.

METHODS

The ischemia-reperfusion-induced oxidative cell damage, and changes in the intracellular signaling mediated by reactive oxygen species and peroxynitrite were studied on rat hearts in a Langendorff perfusion system (n=15). The effect of carvedilol on red blood cell suspension viscosity (hematocrit: 60%) incubated with free radical generator (phenazine methosulphate) was also investigated (n=10). The measurements were performed on a capillary viscosimeter.

RESULTS

In both studies a protective effect of carvedilol was found, as the decrease of red blood cell suspension viscosity and K(+) concentration in the supernatant indicated. Carvedilol significantly decreased the ischemia-reperfusion-induced free radical production and the NAD(+) catabolism and reversed the poly- and mono(ADP-ribosyl)ation. Carvedilol also decreased the lipid peroxidation and membrane damages as determined by free malondialdehyde production and the release of intracellular enzymes. The self ADP-ribosylation of isolated poly(ADP-ribose) polymerase was also significantly inhibited by carvedilol.

CONCLUSION

Our results show that carvedilol can modulate the reactive-oxygen-species-induced signaling through poly- and mono(ADP-ribosyl)ation reactions, the NAD(+) catabolism in postischemic perfused hearts and has a marked scavenger effect on free radical generator-induced red blood cell membrane damage. All these findings may play an important role in the beneficial effects of carvedilol treatment in different cardiovascular diseases.

Red blood cell aggregation measurements in whole blood and in fibrinogen solutions by different methods

Red blood cell (RBC) aggregation is an important component of whole blood viscosity, especially at low shear rates, and is the major cause of the non-Newtonian flow properties of normal blood. In different laboratories several methods are used to determine RBC aggregation, therefore the standardization of aggregation measurements is especially important for getting comparable results. Aggregation indices of 62 human blood samples were determined by two different methods; LORCA (Laser-assisted Optical Rotational Cell Analyzer) and Myrenne aggregometers and related to plasma fibrinogen concentration. Our results show closer correlation values between RBC aggregation and fibrinogen concentration, when RBC aggregation was measured by LORCA (p<0.001), although correlation could be revealed with Myrenne, when plasma fibrinogen level was less than 4.5 g/l. Correlation coefficient between aggregation indices measured by LORCA and Myrenne aggregometers was also closer below this fibrinogen level. In vitro examination of RBC aggregation in fibrinogen solutions showed that higher fibrinogen concentration results in higher RBC aggregation only up to a certain level similarly to that found in human whole blood samples. Our results show that plasma fibrinogen level has an important, concentration dependent effect on RBC aggregation in human blood, but above a certain level it may not cause further aggregate formation.

Effects of doxazosin on hemorheological, hemodynamic and lipid parameters in patients with essential hypertension

It is known from previous studies that hemorheological parameters are altered in patients with essential hypertension. The hemorheological and hemodynamical effects of doxazosin, a selective alpha-1-adrenoreceptor blocker agent, was examined in twenty patients (mean age: 54+/-10 years) with essential hypertension. Hemorheologic (hematocrit, fibrinogen, plasma and whole blood viscosity) and hemodynamic (cardiac output and index, total peripheral resistance) parameters and plasma lipids were determined. The measurements were carried out before the beginning of the treatment, after 1 week and after 12 weeks treatment periods. Besides significant reduction of blood pressure and total peripheral resistance (p < 0.001), a decrease in cholesterol (p < 0.001) and triglyceride (p < 0.01) levels and a beneficial effect on hemorheological parameters was detected. Fibrinogen and plasma viscosity decreased significantly (p < 0.01). Hematocrit value was also lower after one week (p < 0.001), then an increase could be seen. Whole blood viscosity showed similar changes as hematocrit, but the degree of its final increase was slighter, which was supported by the significantly lower value of corrected blood viscosity (p < 0.05).

Hemorheological and hemodynamic parameters in patients with essential hypertension and their modification by alpha-1 inhibitor drug treatment

Hemorheological factors play an important role in the pathogenesis of different cardiovascular diseases. The hemorheological and hemodynamic parameters in essential hypertension and their possible modification by antihypertensive treatment were examined in the following two studies. In the first study the fundus appearance and hemorheological parameters (plasma and whole blood viscosity (WBV), fibrinogen level) of 33 hypertensive patients (mean age: 55 years) were examined. The fundus appearance showed retinopathy in all the cases between stages I-III. All the measured hemorheological parameters of the examined patients were in the pathological range (WBV at 90 s(-1): 5.18 mPa s) and were significantly (p < 0.01) higher than in healthy controls (WBV at 90 s(-1): 4.18 mPa s). The hemorheological factors showed a parallel deterioration with the fundus appearance, namely their values were significantly (p < 0.01) higher in patients with a fundus appearance stage III (WBV at 90 s(-1): 6.02 mPa s) than stage I (WBV at 90 s(-1): 4.51 mPa s). These results show that there is a correlation between hemorheological parameters and fundus appearance in hypertensives, and this suggests that hemorheological factors may play a role in the development of hypertensive retinopathy. In the second study the hemorheological and hemodynamical effects of Doxazosin, a selective alpha-1-adrenoreceptor blocker agent, was examined in twenty patients (mean age: 54 years) with essential hypertension. Hemorheologic (hematocrit, fibrinogen, plasma and whole blood viscosity) and hemodynamic (cardiac output and index, total peripheral resistance) parameters and plasma lipids were determined. The measurements were carried out before the beginning of the treatment, after 1 week and after 12 weeks treatment periods. Besides significant reduction of blood pressure and total peripheral resistance (p < 0.001), a decrease in cholesterol (p < 0.001) and triglycerides (p < 0.01) levels and a beneficial effect on hemorheological parameters was detected. Fibrinogen and plasma viscosity decreased significantly (p < 0.01). Hematocrit value was also lower after one week (p < 0.001), then an increase could be seen. Whole blood viscosity showed similar changes as hematocrit, but the degree of its final increase was slighter, which was supported by the significantly lower value of corrected blood viscosity (p < 0.05). All these findings indicate that hemorheological factors may play a role in the pathogenesis and in the development of organ damages in hypertension.

Hemorheological parameters in coronary artery disease

Hemorheological parameters are primary risk factors in ischemic heart disease (IHD). In the present study the relation of these parameters to the severity of coronary artery disease (CAD) was examined. The data of 109 patients (mean age: 55+/-9 years) undergoing coronary angiography and 59 healthy controls (mean age:35+/-10 years) were analyzed. Hemorheological parameters (hematocrit, fibrinogen level, plasma viscosity (PV) and apparent whole blood viscosity (WBV)) were determined and the circulatory index (CRI) was calculated. Patients were classified into three groups according to their coronary vessel state based on the coronary angiogram: Group 1 (n = 19, mean age: 53+/-8 years) without significant CAD, Group 2 (n = 19, mean age: 51+/-11 years) with single vessel disease, Group 3 (n = 71, mean age: 57+/-8 years) with multivessel disease. All the measured hemorheological parameters of IHD patients were significantly higher than those of controls. Fibrinogen and PV were significantly elevated in Groups 2 and 3 compared with Group 1 (p < 0.05 and 0.01). Hematocrit and WBV were significantly increased in Group 3 compared with Groups 1 and 2 (p < 0.05). CRI was significantly decreased in IHD patients, and it was also lower in Group 3 than in Group 2 (p < 0.05). These results indicate that hemorheological parameters may play a role in the pathogenesis and development of CAD.