Arterial stiffness index beta and cardio-ankle vascular index inherently depend on blood pressure but can be readily corrected

Objectives: Arterial stiffness index beta and cardio-ankle vascular index (CAVI) are widely accepted to quantify the intrinsic exponent (beta(0)) of the blood pressure (BP)-diameter relationship. CAVI and b assume an exponential relationship between pressure (P) and diameter (d). We aim to demonstrate that, under this assumption, beta and CAVI as currently implemented are inherently BP-dependent and to provide corrected, BP-independent forms of CAVI and beta.Methods and results: In P = P(ref)e(beta 0[(d/dref)-1)], usually reference pressure (P-ref) and reference diameter (d(ref)) are substituted with DBP and diastolic diameter to accommodate measurements. Consequently, the resulting exponent is not equal to the pressure-independent beta(0). CAVI does not only suffer from this 'reference pressure' effect, but also from the linear approximation of (dP=dd). For example, assuming beta(0) = 7, an increase of SBP/DBP from 110/70 to 170/120mmHg increased beta by 8.1% and CAVI by 14.3%. We derived corrected forms of b and of CAVI (CAVI(0)) that indeed did not change with BP and represent the pressure-independent beta(0). To substantiate the BP effect on CAVI in a typical follow-up study, we realistically simulated patients (n = 161) before and following BP-lowering 'treatment' (assuming no follow-up change in intrinsic beta(0) and therefore in actual P-d relationship). Lowering BP from 160 +/- 14/111 +/- 11 to 120 +/- 15/79 +/- 11 mmHg (p &lt;0.001) resulted in a significant CAVI decrease (from 8.1 +/- 2.0 to 7.7 +/- 2.1, p = 0.008); CAVI(0) did not change (9.8 +/- 2.4 and 9.9 +/- 2.6, p = 0.499).Conclusion: beta and CAVI as currently implemented are inherently BP-dependent, potentially leading to erroneous conclusions in arterial stiffness trials. BP-independent forms are presented to readily overcome this problem.</p

Principles of cerebral hemodynamics when intracranial pressure is raised: lessons from the peripheral circulation.

BACKGROUND: The brain is highly vascular and richly perfused, and dependent on continuous flow for normal function. Although confined within the skull, pressure within the brain is usually less than 15 mmHg, and shows small pulsations related to arterial pulse under normal circumstances. Pulsatile arterial hemodynamics in the brain have been studied before, but are still inadequately understood, especially during changes of intracranial pressure (ICP) after head injury. METHOD: In seeking cohesive explanations, we measured ICP and radial artery pressure (RAP) invasively with high-fidelity manometer systems, together with middle cerebral artery flow velocity (MCAFV) (transcranial Doppler) and central aortic pressure (CAP) generated from RAP, using a generalized transfer function technique, in eight young unconscious, ventilated adults following closed head trauma. We focused on vascular effects of spontaneous rises of ICP ('plateau waves'). RESULTS: A rise in mean ICP from 29 to 53 mmHg caused no consistent change in pressure outside the cranium, or in heart rate, but ICP pulsations increased in amplitude from 8 to 20 mmHg, and ICP waveform came to resemble that in the aorta. Cerebral perfusion pressure (=central aortic pressure - ICP), which equates with transmural pressure, fell from 61 to 36 mmHg. Mean MCAFV fell from 53 to 40 cm/s, whereas pulsatile MCAFV increased from 77 to 98 cm/s. These significant changes (all P < 0.01) may be explained using the Monro-Kellie doctrine, because of compression of the brain, as occurs in a limb when external pressure is applied. CONCLUSION: The findings emphasize importance of reducing ICP, when raised, and on the additional benefits of reducing wave reflection from the lower body.This study was supported by the National Institute of Health Research, the Biomedical Research Centre (Neuroscience Theme), and the Medical Research Council (Grants G0600986 and G9439390). J.D.P. has received the NIHR Investigator Awards. M.O.K. is sponsored by an Australian Postgraduate Awards Industrial Linkage Grant from the Australian Research Council (LP0884094), with AtCor Medical Australia as the collaborating organization.This is the final version of the article. It first appeared from Wolters Kluwer via http://dx.doi.org/10.1097/HJH.000000000000053

Comparison Between Invasive and Noninvasive Methods to Estimate Subendocardial Oxygen Supply and Demand Imbalance

Background Estimation of the balance between subendocardial oxygen supply and demand could be a useful parameter to assess the risk of myocardial ischemia. Evaluation of the subendocardial viability ratio (SEVR, also known as Buckberg index) by invasive recording of left ventricular and aortic pressure curves represents a valid method to estimate the degree of myocardial perfusion relative to left ventricular workload. However, routine clinical use of this parameter requires its noninvasive estimation and the demonstration of its reliability. Methods and Results Arterial applanation tonometry allows a noninvasive estimation of SEVR as the ratio of the areas directly beneath the central aortic pressure curves obtained during diastole (myocardial oxygen supply) and during systole (myocardial oxygen demand). However, this "traditional" method does not account for the intra-ventricular diastolic pressure and proper allocation to systole and diastole of left ventricular isometric contraction and relaxation, respectively, resulting in an overestimation of the SEVR values. These issues are considered in the novel method for SEVR assessment tested in this study. SEVR values estimated with carotid tonometry by "traditional" and "new" method were compared with those evaluated invasively by cardiac catheterization. The "traditional" method provided significantly higher SEVR values than the reference invasive SEVR: average of differences +/- SD= 44 +/- 11% (limits of agreement: 23% - 65%). The noninvasive "new" method showed a much better agreement with the invasive determination of SEVR: average of differences +/- SD= 0 +/- 8% (limits of agreement: -15% to 16%). Conclusions Carotid applanation tonometry provides valid noninvasive SEVR values only when all the main factors determining myocardial supply and demand flow are considered

Age-Specific Acute Changes in Carotid-Femoral Pulse Wave Velocity With Head-up Tilt

BACKGROUND: Aortic stiffness as measured by carotid-femoral pulse wave velocity (cfPWV) is known to depend on blood pressure (BP), and this dependency may change with age. Therefore, the hydrostatic BP gradient resulting from a change in body posture may elicit a cfPWV change that is age-dependent. We aimed to analyze the relationship between BP gradient-induced by head-up body tilting-and related changes in cfPWV in individuals of varying age. METHODS: cfPWV and other hemodynamic parameters were measured in 30 healthy individuals at a head-up tilt of 0° (supine), 30°, and 60°. At each angle, the PWV gradient and resulting cfPWV were also estimated (predicted) by assuming a global nonlinear, exponential, pressure-diameter relationship characterized by a constant β0, and taking into account that (diastolic) foot-to-foot cfPWV acutely depends on diastolic BP. RESULTS: cfPWV significantly increased upon body tilting (8.0 ± 2.0 m/s supine, 9.1 ± 2.6 m/s at 30°, 9.5 ± 3.2 m/s at 60°, P for trend <0.01); a positive trend was also observed for heart rate (HR; P < 0.01). When the observed, tilt-induced cfPWV change measured by applanation tonometry was compared with that predicted from the estimated BP hydrostatic gradient, the difference in observed-vs.-predicted PWV change increased nonlinearly as a function of age (R2 for quadratic trend = 0.38, P < 0.01, P vs. linear = 0.04). This result was unaffected by HR tilt-related variations (R2 for quadratic trend = 0.37, P < 0.01, P vs. linear = 0.04). CONCLUSIONS: Under a hydrostatic pressure gradient, the pulse wave traveling along the aorta undergoes an age-related, nonlinear PWV increase exceeding the increase predicted from BP dependency

Standalone vertex finding in the ATLAS muon spectrometer

A dedicated reconstruction algorithm to find decay vertices in the ATLAS muon spectrometer is presented. The algorithm searches the region just upstream of or inside the muon spectrometer volume for multi-particle vertices that originate from the decay of particles with long decay paths. The performance of the algorithm is evaluated using both a sample of simulated Higgs boson events, in which the Higgs boson decays to long-lived neutral particles that in turn decay to bbar b final states, and pp collision data at √s = 7 TeV collected with the ATLAS detector at the LHC during 2011

Measurements of Higgs boson production and couplings in diboson final states with the ATLAS detector at the LHC

Measurements are presented of production properties and couplings of the recently discovered Higgs boson using the decays into boson pairs, H →γ γ, H → Z Z∗ →4l and H →W W∗ →lνlν. The results are based on the complete pp collision data sample recorded by the ATLAS experiment at the CERN Large Hadron Collider at centre-of-mass energies of √s = 7 TeV and √s = 8 TeV, corresponding to an integrated luminosity of about 25 fb−1. Evidence for Higgs boson production through vector-boson fusion is reported. Results of combined fits probing Higgs boson couplings to fermions and bosons, as well as anomalous contributions to loop-induced production and decay modes, are presented. All measurements are consistent with expectations for the Standard Model Higgs boson

Measurement of the top quark pair cross section with ATLAS in pp collisions at √s=7 TeV using final states with an electron or a muon and a hadronically decaying τ lepton

A measurement of the cross section of top quark pair production in proton-proton collisions recorded with the ATLAS detector at the Large Hadron Collider at a centre-of-mass energy of 7 TeV is reported. The data sample used corresponds to an integrated luminosity of 2.05 fb -1. Events with an isolated electron or muon and a τ lepton decaying hadronically are used. In addition, a large missing transverse momentum and two or more energetic jets are required. At least one of the jets must be identified as originating from a b quark. The measured cross section, σtt-=186±13(stat.)±20(syst.)±7(lumi.) pb, is in good agreement with the Standard Model prediction

Hunt for new phenomena using large jet multiplicities and missing transverse momentum with ATLAS in 4.7 fb−1 of √s=7 TeV proton-proton collisions

Results are presented of a search for new particles decaying to large numbers of jets in association with missing transverse momentum, using 4.7 fb−1 of pp collision data at s√=7TeV collected by the ATLAS experiment at the Large Hadron Collider in 2011. The event selection requires missing transverse momentum, no isolated electrons or muons, and from ≥6 to ≥9 jets. No evidence is found for physics beyond the Standard Model. The results are interpreted in the context of a MSUGRA/CMSSM supersymmetric model, where, for large universal scalar mass m 0, gluino masses smaller than 840 GeV are excluded at the 95% confidence level, extending previously published limits. Within a simplified model containing only a gluino octet and a neutralino, gluino masses smaller than 870 GeV are similarly excluded for neutralino masses below 100 GeV

2024 Recommendations for Validation of Noninvasive Arterial Pulse Wave Velocity Measurement Devices

BACKGROUND: Arterial stiffness, as measured by arterial pulse wave velocity (PWV), is an established biomarker for cardiovascular risk and target-organ damage in individuals with hypertension. With the emergence of new devices for assessing PWV, it has become evident that some of these devices yield results that display significant discrepancies compared with previous devices. This discrepancy underscores the importance of comprehensive validation procedures and the need for international recommendations. METHODS: A stepwise approach utilizing the modified Delphi technique, with the involvement of key scientific societies dedicated to arterial stiffness research worldwide, was adopted to formulate, through a multidisciplinary vision, a shared approach to the validation of noninvasive arterial PWV measurement devices. RESULTS: A set of recommendations has been developed, which aim to provide guidance to clinicians, researchers, and device manufacturers regarding the validation of new PWV measurement devices. The intention behind these recommendations is to ensure that the validation process can be conducted in a rigorous and consistent manner and to promote standardization and harmonization among PWV devices, thereby facilitating their widespread adoption in clinical practice. CONCLUSIONS: It is hoped that these recommendations will encourage both users and developers of PWV measurement devices to critically evaluate and validate their technologies, ultimately leading to improved consistency and comparability of results. This, in turn, will enhance the clinical utility of PWV as a valuable tool for assessing arterial stiffness and informing cardiovascular risk stratification and management in individuals with hypertension

Data monitoring roadmap. The experience of the Italian Multiple Sclerosis and Related Disorders Register

Introduction Over the years, disease registers have been increasingly considered a source of reliable and valuable population studies. However, the validity and reliability of data from registers may be limited by missing data, selection bias or data quality not adequately evaluated or checked.This study reports the analysis of the consistency and completeness of the data in the Italian Multiple Sclerosis and Related Disorders Register.MethodsThe Register collects, through a standardized Web-based Application, unique patients.Data are exported bimonthly and evaluated to assess the updating and completeness, and to check the quality and consistency. Eight clinical indicators are evaluated.ResultsThe Register counts 77,628 patients registered by 126 centres. The number of centres has increased over time, as their capacity to collect patients.The percentages of updated patients (with at least one visit in the last 24 months) have increased from 33% (enrolment period 2000-2015) to 60% (enrolment period 2016-2022). In the cohort of patients registered after 2016, there were &gt;= 75% updated patients in 30% of the small centres (33), in 9% of the medium centres (11), and in all the large centres (2).Clinical indicators show significant improvement for the active patients, expanded disability status scale every 6 months or once every 12 months, visits every 6 months, first visit within 1 year and MRI every 12 months.ConclusionsData from disease registers provide guidance for evidence-based health policies and research, so methods and strategies ensuring their quality and reliability are crucial and have several potential applications