K. McNeill

King's College London, Londinium, England, United Kingdom

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Publications (9)26.51 Total impact

  • Artery Research 12/2014; 8(4).
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    ABSTRACT: Pulse wave velocity (PWV), a measure of arterial stiffness strongly predictive of cardiovascular risk in adults, is usually measured by sequential ECG-referenced carotid and femoral tonometry. A simplified technique, more suitable for use in children, employs simultaneous volumetric recording from a sensor applied over the carotid artery and a cuff applied over the femoral artery or arm and thigh pressure cuffs applied over the brachial and femoral arteries. The purpose of this study was to compare PWV computed over the carotid-femoral path (PWVcf) with that over the brachial-femoral path (PWVbf) using a volumetric system (Vicorder) and to compare values of PWVcf obtained by the volumetric and a tonometric method (SphygmoCor) in children. Vicorder PWVcf and PWVbf were compared in 156 children (3-18 years, 110 with chronic kidney disease), and PWVcf by Vicorder was compared to PWVcf by SphygmoCor in a subset of 122 patients. PWVcf by Vicorder was moderately correlated with PWVcf by SphygmoCor (R = 0.50, P < 0.000). PWVbf and PWVcf Vicorder were more closely correlated (R = 0.75, P < 0.0001), but with a significant systematic difference. Applying a correction factor to PWVbf measurements gave results similar to those obtained over the carotid-femoral path. Within-patient coefficients of variation for repeated measures were 5.9, 7.8, and 8.5% for PWVbf (Vicorder), PWVcf (Vicorder) and PWVcf (SphygmoCor), respectively. All PWV values showed a similar relation to age. Volumetric methods appear reproducible and are easy to use in children, but values obtained by Vicorder and SphygmoCor are not interchangeable even when measured over the same pathway.
    Journal of Hypertension 04/2014; · 4.22 Impact Factor
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    ABSTRACT: Within the general population, levels of C-reactive protein (CRP) are positively associated with atherosclerotic cardiovascular disease (CVD). Whether CRP is causally implicated in atherogenesis or is the results of atherosclerosis is disputed. A role of CRP to protect endothelium-derived nitric oxide (EDNO) has been suggested. We examined the association of CRP with EDNO-dependent vasomotor function and subclinical measures of atherosclerosis and arteriosclerosis in patients with raised CRP resulting from rheumatoid arthritis (RA). Patients with RA (n = 59) and healthy control subjects (n = 123), underwent measures of high sensitivity CRP, flow-mediated dilation (FMD, dependent on EDNO), intima-media thickness (IMT, a measure of subclinical atherosclerosis) and aortic pulse wave velocity (PWV, a measure of arteriosclerosis). IMT and PWV were elevated in patients with RA compared to controls but FMD was similar in the two groups. In patients with RA, IMT and PWV were not correlated with CRP but FMD was positively independently correlated with CRP (P<0.01). These findings argue against a causal role of CRP in atherogenesis and are consistent with a protective effect of CRP on EDNO bioavailability.
    PLoS ONE 01/2010; 5(4):e10242. · 3.53 Impact Factor
  • Artery Research 12/2009; 3(4):164-164.
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    ABSTRACT: Our aim was to examine the relative contributions of the first systolic shoulder (P1) and augmentation pressure (DeltaP(aug)) to central pulse pressure (cPP), their relation to central arterial stiffness (pulse wave velocity [PWV]) and arterial diameters, and their respective heritability estimates. cPP is augmented above P1 by DeltaP(aug) due to pressure waves reflected from the periphery of the circulation. Women (n = 496) from the Twins UK adult twin registry (112 monozygotic, 135 dizygotic pairs) age 21 to 81 years were studied. cPP, P1, and DeltaP(aug) were estimated using the SphygmoCor system (Atcor, West Ryde, Australia) from transformed radial waveforms. Carotid-femoral PWV was measured using the same system. Aortic and femoral artery diameters were measured by ultrasonography. Heritability was estimated using structural equation modeling. P1 and DeltaP(aug) accounted for 22% and 76%, respectively, of the variance in cPP. After adjustment for mean arterial pressure and heart rate, P1 strongly independently positively correlated with PWV (standardized regression coefficient, beta = 0.4, p < 0.0001), whereas DeltaP(aug) did not independently correlate with PWV but independently negatively correlated with the ratio of the diameter of the femoral to that of the abdominal aorta (beta = -0.12, p < 0.001). Estimates of heritability (h(2)) of cPP, PWV, P1, and DeltaP(aug) were 0.43, 0.34, 0.31, and 0.62, respectively, after adjustment for mean arterial pressure and heart rate. These results suggest that, in women, DeltaP(aug) is highly heritable, is associated with the ratio of distal to proximal arterial diameters, and, independent of PWV, is a major determinant of cPP.
    Journal of the American College of Cardiology 09/2009; 54(8):695-703. · 14.09 Impact Factor
  • Artery Research 01/2009; 3(4):153-153.
  • Artery Research 08/2008; 2(3):86-86.
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    ABSTRACT: Pulse wave velocity (PWV), the speed of propagation of arterial pressure waves through the arterial tree, is related to arterial stiffness and is an important prognostic marker for cardiovascular events. In clinical practice PWV is commonly determined by arterial tonometry, with a noninvasive pressure sensor applied sequentially over carotid and femoral arteries. The electrocardiogram (ECG) is used as a timing reference to determine the time delay or "transit time" between the upstroke of carotid and femoral pulse waveforms. Commercially available vascular ultrasound scanners provide a pulsed wave (PW) Doppler velocity signal, which should allow determination of carotid-femoral transit time and hence PWV. We compared carotid-femoral PWV measured by tonometry and by PW Doppler ultrasound (Seimens, Apsen scanner with 7 MHz linear transducer) in asymptomatic subjects (n = 62, 26 male, aged 21 to 72 y). To test for intra-subject and inter-observer variation, ten subjects were scanned by one observer on two occasions 2 wk apart and by two observers on same day. PWV by tonometry ranged from 5.3 to 15.0 m/s. There was no significant difference between mean values of PWV obtained by the two techniques (mean difference: 0.3 m/s, standard deviation of difference: 1.5 m/s), which were closely correlated (r = 0.83). The coefficient of variation for repeated measures on the same subject by the same observer was 10.1% and the inter-observer coefficient of variation was 5.8%. These results suggest a commercial ultrasound scanner can be used to measure PWV, giving results that are reproducible and closely correlated with those obtained by arterial tonometry. (E-mail: ben_yu.jiang@kcl.ac.uk).
    Ultrasound in Medicine & Biology 04/2008; 34(3):509-12. · 2.46 Impact Factor
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    ABSTRACT: Rheumatoid arthritis (RA) is associated with increased cardiovascular disease (CVD) risk that has been attributed to endothelial dysfunction and inflammation. Non-steroidal anti-inflammatory drugs (NSAIDs) and cyclo-oxygenase (COX)-2 inhibitors have been shown in some studies to improve endothelial function in subjects without RA. The aim of this study was to investigate the effects of COX inhibition on endothelial function in patients with RA. Patients with RA (n = 37) were randomized to receive a 2-week course of either indomethacin (75 mg bd), rofecoxib (12.5 mg bd), or placebo in a double-blind study. Endothelial function was measured using flow-mediated dilation (FMD) of the brachial artery in response to reactive hyperaemia. Arterial stiffness was also assessed using pulse wave analysis (PWA) through the measurement of the aortic augmentation index (AIx). Measurements of vascular function and inflammatory markers were taken before and at the end of the treatment period. There were no significant differences in changes in FMD, AIx, blood pressure (BP), serum creatinine, erythrocyte sedimentation rate (ESR), or high-sensitivity C-reactive protein (hsCRP) between groups. However, compared with the other treatment groups, there was a tendency for systolic BP to decrease in the placebo group (p = 0.063) and for creatinine to increase in the indomethacin and rofecoxib groups after treatment (p = 0.054). This study suggests that COX inhibition by indomethacin or rofecoxib do not improve endothelial function in patients with RA.
    Scandinavian Journal of Rheumatology 01/2007; 36(4):265-9. · 2.22 Impact Factor