Hemorheology, ankle brachial pressure index (ABPI) and toe brachial pressure index (TBPI) in metabolic syndrome
Introduction
Metabolic syndrome (MetS) is the constellation of risk factors, the presence of which is associated with increased risk of developing cardiovascular diseases (CVD) (Isomaa et al., 2001, Lakka et al., 2002). Microvascular dysfunction is associated with MetS and its components (Czernichow et al., 2010, Serné et al., 2007, Vykoukal and Davies, 2011). The experiment of Frisbee and Stepp, on the obese zucker rat model, demonstrated reduced vasodilation of skeletal muscle to nitric oxide stimuli (Frisbee and Stepp, 2001). Same authors through series of experiments showed chronic reductions in the blood flow in a hind limb of obese Zucker rat model with MetS. Wall thickness and lumen of the vessels supplying hind limb were reduced and the compliance of the vessels wall was lost (Frisbee and Stepp, 2001, Stepp and Frisbee, 2002, Stepp et al., 2004). Microvascular abnormalities affect the pressure and the flow of the blood (Levy et al., 2001, Serné et al., 2007). Another important aspect of microcirculation that affects the pressure and flow of blood is hemorheology (Baskurt and Meiselman, 2003, Pirrelli, 1999, Sandhagen, 1999). Hemorheological parameters such as increased whole blood viscosity (WBV), reduced erythrocyte deformability, increased erythrocyte aggregation and altered erythrocyte morphology have been associated with MetS (Gyawali et al., 2012a, Gyawali et al., 2012b, Gyawali, 2014). Altered hemorheology has been shown to negatively affect microcirculation (Konstantinova et al., 2004).
Measurement of ankle brachial pressure index (ABPI) by using Doppler ultrasound device is the commonly used clinical method of assessing peripheral arterial disease and circulation in the lower limb (Vowden et al., 1996). However, the validity of measuring ABPI in diabetic subjects due to lower limb artery calcification has been questioned (Brooks et al., 2001, Mayfield et al., 1998). Recent literature has supported the use of the toe brachial pressure index (TBPI) for assessing circulation as it overcomes the medium vessel calcification problem seen, in the lower limb of patients with type II diabetes mellitus (DM) (Brooks et al., 2001, Mayfield et al., 1998). The objective of our study was to assess macro and microvascular abnormalities in MetS and compare the strength of association of the ABPI, TBPI and hemorheological parameters with MetS.
Section snippets
Subjects
One hundred (100) participants were recruited from a rural town of Australia from June to Dec, 2013. Pregnant women, non-ambulatory patients and children under 18 years of age were excluded from the study. Recruited participants were divided into three groups on the basis of the absence or presence of MetS and its components. A modified NCEP-ATPIII guideline was referred to define MetS (Expert panel on detection evaluation treatment of high blood cholesterol in adults, 2001, Grundy et al., 2004
Anthropometric and blood pressure measurement
Waist circumference of the participants was measured from the upper margin of the posterior iliac crest at the end of normal expiration directly above the skin. Brachial blood pressure was measured with an automated BP machine (Welch Allyn®) in a supine position from both arms. Toe brachial pressure was measured from the great toe of both legs using SysToe (ATYS medical) that uses photoplethysmography (PPG) analyzed by a unique patented algorithm designed by Atys Medical. TBPI was calculated by
Results
Thirty-one participants formed group I, thirty-three formed group II and thirty-six formed group III. Mean age of the participants was compared into the three groups of classification using ANOVA tests. The difference in mean age between the three groups (45.48 ± 8.974, 56.52 ± 12.94 and 63.06 ± 12.13 years) was statistically significant (P < 0.0005). Tukey post-hoc analysis revealed that the increase from group I to II (P = 0.001) and from group I to III (P < 0.0005) was significant but age difference in
Discussion
Our study showed that WBV and erythrocyte aggregation were higher whereas erythrocyte deformability (lower EImax), was lower in the participants with MetS when compared to the participants without MetS. MetS was significantly associated with the highest quartile of critical stress and WBV and with the lowest quartile of erythrocyte deformability. Our findings are in line with reports from Zhang et al. which showed that the mean WBV level was progressively higher in groups with higher number of
Conclusions
Both microcirculation defect and macrovascular circulation defect were present in MetS. All of the hemorheological parameters were significantly associated with MetS. The association of hemorheological parameters was stronger than the association of TBPI and ABPI with MetS. Altered hemorheology could be the bridge that connects MetS with increased CVD. Also, defect in microcirculation due to altered hemorheology could be one of the several pathogenic mechanisms underlying complications of MetS.
References (46)
Possible role of increased blood viscosity in the hemodynamics of systemic hypertension
Am. J. Cardiol.
(2000)Prevalence of the metabolic syndrome in patients with coronary heart disease, cerebrovascular disease, peripheral arterial disease or abdominal aortic aneurysm
Atherosclerosis
(2004)Toe brachial index in middle aged patients with diabetes mellitus type 2: Not just a peripheral issue
Diabetes Res. Clin. Pract.
(2013)- et al.
Vascular biology of metabolic syndrome
J. Vasc. Surg.
(2011) Blood rheological properties are strongly related to the metabolic syndrome in middle-aged Chinese
Int. J. Cardiol.
(2006)Parameterization of red blood cell elongation index – shear stress curves obtained by ektacytometry
Scand. J. Clin. Lab. Invest.
(2009)- et al.
Blood rheology and hemodynamics
Semin. Thromb. Hemost.
(2003) Effect of erythrocyte aggregation on velocity profiles in venules
Am. J. Physiol. Heart Circ. Physiol.
(2001)TBI or not TBI: that is the question. Is it better to measure toe pressure than ankle pressure in diabetic patients?
Diabet. Med.
(2001)Contribution of red blood cell aggregation to venous vascular resistance in skeletal muscle
Am. J. Physiol. Heart Circ. Physiol.
(1997)