Carotid-femoral pulse wave velocity estimated by an ultrasound system

To date, regional aortic stiffness can be evaluated by the reference tonometric technique via the pulse wave velocity (PWV) measured in two points: the carotid and the femoral arteries. Based on a similar intersecting tangent algorithm, we have developed a new method for the determination of carotid-femoral PWV using a high-resolution echo tracking ultrasound system. Herein, PWV can be computed from the measurement of the transit time between the foot of the carotid diameter waveform and the foot of the femoral diameter waveform. The study was carried out on 50 consecutive patients at rest (29 men, mean age 30 ± 18 yrs) recruited on the occasion of a vascular screening for atherosclerosis. Carotid-femoral PWV was determined by a trained operator using a tonometric technique, (PWVpp, PulsePen, Italy), and an echotracking ultrasound system, (PWVus, e-tracking Alpha 10, Aloka, Japan). Relationship between PWVpp and PWVus was evaluated by linear regression. A Pearson’s correlation coefficient of r=0.95 was found between both variables (95% confidence interval 0.90-0.99; P<0.0001; PWVus= 0,91*PWVpp+0.44). The Bland–Altman plot comparing PWVpp and PWVus showed a systematic offset of -0.07 m.s-1 with a limit of agreement from -1,33 to 1,19 m.s-1. Our results show an excellent and significant correlation between both techniques which confirms that ultrasound system can provide a reliable estimate of the regional aortic stiffness like the tonometric technique does. Additional studies are now needed to show the simplicity of the measurement using ultrasound system while maintaining reliability even in overweight patients

Brachial artery vasodilatory response and wall shear rate determined by multi-gate Doppler in a healthy young cohort

This is the author accepted manuscript. The final version is available from American Physiological Society via the DOI in this record.Wall shear rate (WSR) is an important stimulus for the brachial artery flow-mediated dilation (FMD) response. However, WSR estimation near the arterial wall by conventional Doppler is inherently difficult. To overcome this limitation, we utilised multi-gate Doppler to accurately determine the WSR stimulus near the vessel wall simultaneously with the FMD response using an integrated FMD system [Ultrasound Advanced Open Platform (ULA-OP)]. Using the system, we aimed to perform a detailed analysis of WSR-FMD response and establish novel WSR parameters in a healthy young population. Data from 33 young healthy individuals (27.5±4.9yrs, 19F) were analysed. FMD was assessed with reactive hyperemia using ULA-OP. All acquired raw data were post-processed using custom-designed software to obtain WSR and diameter parameters. The acquired velocity data revealed that non-parabolic flow-profiles within the cardiac cycle and under different flow-states, with heterogeneity between participants. We also identified seven WSR magnitude and four WSR time-course parameters. Among them, WSR area under the curve until its return to baseline was the strongest predictor of the absolute (R2 =0.25) and percentage (R2 =0.31) diameter changes in response to reactive hyperemia. For the first time, we identified mono- and biphasic WSR stimulus patterns within our cohort that produced different magnitudes of FMD response [absolute diameter change: 0.24±0.10mm (monophasic) vs 0.17±0.09mm (biphasic), p<0.05]. We concluded that accurate and detailed measurement of the WSR stimulus is important to comprehensively understand the FMD response and that this advance in current FMD technology could be important to better understand vascular physiology and pathology.This study was supported by the European Union’s Seventh Framework Programme (FP7/2007-2013) for the Innovative Medicine Initiative under grant agreement number IMI/115006 (the SUMMIT consortium), in part by the National Institute of Health Research (NIHR) Exeter Clinical Research Facility, and by the Italian Ministry of University and Research (MIUR, Project PRIN 2010-2011)

Carotid artery stiffness in metabolic syndrome: Sex differences

Introduction: The effect of metabolic syndrome (MS) on carotid stiffness (CS) in the context of gender is under research. Objective: We examined the relationship between the MS and CS in men (M) and women (W) and investigated if the impact of cardiovascular risk factors on CS is modulated by gender. Patients and Methods: The study included 419 subjects (mean age 54.3 years): 215 (51%) with MS (109 W and 106 M) and 204 (49%) without MS (98 W and 106 M). Carotid intima-media thickness (IMT) and CS parameters (beta stiffness index (beta), Peterson’s elastic modulus (Ep), arterial compliance (AC) and one-point pulse wave velocity (PWV-beta)) were measured with the echo-tracking (eT) system. Results: ANCOVA demonstrated that MS was associated with elevated CS indices (p = 0.003 for beta and 0.025 for PWV-beta), although further sex-specific analysis revealed that this relationship was significant only in W (p = 0.021 for beta). Age was associated with CS in both M and W, pulse pressure (PP) and body mass index turned out to be determinants of CS solely in W, while the effect of mean arterial pressure (MAP) and heart rate was more pronounced in M. MANOVA performed in subjects with MS revealed that age and diabetes mellitus type 2 were determinants of CS in both sexes, diastolic blood pressure and MAP – solely in M and systolic blood pressure, PP and waist circumference – solely in W (the relationship between the waist circumference and AC was paradoxical). Conclusion: The relationship between MS and CS is stronger in W than in M. In subjects with MS, various components of arterial pressure exert different sex-specific effects on CS – with the impact of the pulsative component of arterial pressure (PP) observed in W and the impact of the steady component (MAP) observed in M

Time course of forearm arterial compliance changes during reactive hyperemia

Ultrasonic studies have shown that arterial compliance increases after prolonged ischemia. The objective of the present study was to develop an alternative plethysmographic method to investigate compliance, exploring validity and clinical applicability. Forearm pulse volume (FPV) and blood pressure (BP) were used to establish the FPV-BP relationship. Forearm arterial compliance (FAC) was measured, and the area under the FAC-BP curve (FAC(AUC)) was determined. The time course curve of compliance changes during reactive hyperemia was obtained by continuous measurements of FAC(AUC) for 20 s before and for 300 s after arterial occlusion. This technique allows us to effectively assess compliance changes during reactive hyperemia. Furthermore, the selected measurement protocol indicated the necessity for continuous measurements to detect "true" maximal FAC(AUC) changes. On multivariate analysis, preischemic FAC(AUC) was mainly affected by sex, peak FAC(AUC) was affected by sex and systolic BP, percent changes were affected by plasma high-density and low-density lipoprotein cholesterol, peak time was affected by age and body mass index, and descent time was affected by plasma triglyceride levels. The proposed technique is highly sensitive and well comparable with the generally accepted echotracking system. It may thus be considered as an alternative tool to detect and monitor compliance changes induced by arterial occlusion

A Genome-Wide Association Study of Diabetic Kidney Disease in Subjects With Type 2 Diabetes

dentification of sequence variants robustly associated with predisposition to diabetic kidney disease (DKD) has the potential to provide insights into the pathophysiological mechanisms responsible. We conducted a genome-wide association study (GWAS) of DKD in type 2 diabetes (T2D) using eight complementary dichotomous and quantitative DKD phenotypes: the principal dichotomous analysis involved 5,717 T2D subjects, 3,345 with DKD. Promising association signals were evaluated in up to 26,827 subjects with T2D (12,710 with DKD). A combined T1D+T2D GWAS was performed using complementary data available for subjects with T1D, which, with replication samples, involved up to 40,340 subjects with diabetes (18,582 with DKD). Analysis of specific DKD phenotypes identified a novel signal near GABRR1 (rs9942471, P = 4.5 x 10(-8)) associated with microalbuminuria in European T2D case subjects. However, no replication of this signal was observed in Asian subjects with T2D or in the equivalent T1D analysis. There was only limited support, in this substantially enlarged analysis, for association at previously reported DKD signals, except for those at UMOD and PRKAG2, both associated with estimated glomerular filtration rate. We conclude that, despite challenges in addressing phenotypic heterogeneity, access to increased sample sizes will continue to provide more robust inference regarding risk variant discovery for DKD.Peer reviewe

Coronary vasodilator capacity and exercise-induced myocardial ischemia are related to the pulsatile component of blood pressure in patients with essential hypertension

Abstract: Objectives High pulsatile load is associated with structural alterations of the heart and arteries, which may cause changes in the coronary circulation and predispose to myocardial ischemia. This study was designed to investigate the relationships of coronary vasodilator capacity and exercise-induced myocardial ischemia to pulsatile and steady components of office blood pressure. Methods Eighty-two untreated, middle-aged hypertensive patients without coronary artery stenosis and 23 normotensive volunteers, underwent exercise electrocardiogram test and standard and transesophageal echocardiography to assess the occurrence of myocardial ischemia, left ventricular (LV) mass and geometry, total arterial compliance and coronary vasodilator capacity. Results In the hypertensive population, minimum coronary resistance (MCR) was significantly higher (P < 0.01) in the top as compared to all three lower pulse pressure (PP) quartiles (1.10 +/- 0.19, 1.21 +/- 0.23, 1.20 +/- 0.26 and 1.43 +/- 0.26 mmHg s/cm). An additional increase in MCR also occurred in the top quartile of systolic blood pressure (SBP), but not across quartiles of mean blood pressure. In regression analysis, MCR increased with PP, SBP and LV wall thickness and decreased with total arterial compliance. As compared to hypertensive patients with a negative exercise test for myocardial ischemia (n = 30), those with a positive test (n = 20) had higher MCR (1.12 +/- 0.22 versus 1.39 +/- 0.29 mmHg s/cm, P< 0.01) and lower total arterial compliance (96 +/- 22 versus 81 +/- 16%, P< 0.01). Conclusions In untreated middle-aged hypertensive patients, coronary vasodilator capacity declines with increasing office PP and SBP. A decreased arterial compliance and increased LV wall thickness appear to be major alterations underlying this relationship. Exercise-induced myocardial ischemia is associated with higher MCR and lower arterial compliance