Littérature scientifique sur le sujet « Tonometria arteriosa »

The aim to demonstrate that subclinical atherosclerosis and vascular rigidity in a postmenopausal patient without clinical sings of cardiovascular disease and osteoporosis are connected with a decreased bone mass.Materials and methods. Patient O., 64 years old, was examined at the National Medical Research Center for Preventive Medicine within the program “Comprehensive assessment of total risks and early preclinical markers of osteoporosis and atherosclerosis complications”. No complaints during the examination were revealed. Laboratory tests were performed to evaluate blood lipids level, calcium-phosphorus metabolism, determine marker of bone resorption – CTX (β-crosslaps), measure levels of vitamin D and parathyroid hormone. Instrumental examinations included dual-energy x-ray absorptiometry of the spine and femoral neck, carotid ultrasound, applanation tonometry, multispiral computed tomography of coronary arteries with calcium score determination.Results. During outpatient examination, densitometry revealed decreased bone mineral density in the lumbar spine and in the femoral neck, corresponding to osteoporosis, carotid ultrasound identified atherosclerotic plaques, multispiral computed tomography of coronary arteries – coronary calcification, applanation tonometry – increased aortic stiffness.Conclusion. The clinical case is an example of early-detected preclinical signs of atherosclerosis and osteoporosis, as well as an increased risk of cardiovascular complications. Due to the high frequency of subclinical atherosclerosis, vessel wall state should be examined in women at the beginning of postmenopause. Signs of vascular stiffness and subclinical atherosclerosis give occasion to assess risk of fractures using the FRAX ® calculator and, if necessary, to diagnose bone mass loss using X-ray densitometry. Proposed algorithm can contribute to the early detection of cardiovascular diseases and at the same time improve fracture risk assessment.

Aim. To study the vasoprotective effects of atorvastatin depending on the achievement of the target level of low-density lipoprotein cholesterol (LDL-C) in patients with ST-segment elevation myocardial infarction (STEMI) within 48 weeks of follow-up. Materials and methods. Included were 112 STEMI patients who received atorvastatin 204080 mg. On days 79 from the onset of the disease, after 24 and 48 weeks, ultrasound examination of the carotid arteries with RF technology and applanation tonometry were performed, the lipid profile was determined. The patients were divided into groups: group 1 (n=41) of highly effective therapy (HET) who achieved the target LDL-C after 24 and 48 weeks; group 2 (n=29) in relatively effective therapy (RET) achieving target values at 24th or 48th week; group 3 (n=42) insufficiently effective therapy (IET) did not reach the target LDL-C. Results. When examining the carotid arteries in the HET group, the intima-media thickness (IMT) decreased by 10.713.1%, the b index by 14.926.3% after 2448 weeks. In the RET group, the IMT regression was 10.413.3%; b index 23.9% by the 48th week. In the IET group, the b index decreased by the 48th week by 14.3%. According to applanation tonometry in the HET group, the central pressure did not change. In the RET group, systolic pressure in the aorta increased by 1015.7% after 2448 weeks, pulse pressure by 33.9% by the end of observation. With IET, the increase was 8.66.8 and 19.825.9%, respectively. The odds ratio of developing endpoints in the RET group was 4.7 (95% CI 1.226.4; p=0.02), in the IET group 3.9 (95% CI 1.124.8; p=0.03) compared with HET. Conclusion. The most pronounced vasoprotective effect and a decrease in cardiovascular risk are associated with the achievement of the target LDL-C throughout the entire treatment period.

The purpose of this study is to evaluate endothelial function in postural tachycardia syndrome (PoTS), a poorly understood chronic condition characterized by a state of consistent orthostatic tachycardia (delta heart rate ≥30 beats per minute) upon standing without orthostatic hypotension. Nineteen patients with PoTS and 9 healthy controls were studied after 3 days of a fixed, caffeine-free, normal sodium (150 milliequivalents/day) diet. All participants underwent autonomic function testing, including sinus arrhythmia, valsalva maneuver, hyperventilation, cold pressor, handgrip, and a standing test with catecholamine measurements, followed by endothelial function testing. We analyzed 3 measures of endothelial function: percent brachial flow-mediated dilation, digital pulsatile arterial tonometry, and postischemic percent leg blood flow. Flow-mediated dilation was significantly lower in patients with PoTS (6.23±3.54% for PoTS) than in healthy controls (10.6±4.37% for controls versus, P =0.014). PoTS and controls had similar digital pulsatile arterial tonometry (1.93±0.40 arbitrary units for controls versus 2.13±0.63 arbitrary units for PoTS). PoTS had similar but suggestive percent leg blood flow to controls (313±158% for PoTS versus 468±236% for controls, P =0.098). Patients with PoTS have significantly reduced flow-mediated dilation compared with healthy controls, suggesting that PoTS is characterized by endothelial dysfunction in conduit arteries. Registration: URL: https://www.clinicaltrials.gov . Unique identifier: NCT01308099.

BackgroundAlpacas are being more frequently presented to veterinarians in the UK. It is important to validate whether published normal ocular parameters are consistent with the alpaca population in the UK.MethodsOphthalmic examinations were performed on healthy alpacas (Vicugna pacos) from three farms in East Anglia, UK.ResultsOn direct ophthalmoscopy of 35 alpacas, there was a 50 per cent prevalence of opacities within the lens in alpacas older than two years old (n=8/16). There was a 36.8 per cent prevalence of persistent hyaloid arteries in alpacas under two years old (n=7/19). The mean Schirmer tear test-1 value was 20.0 ±6 mm/minute (n=40). The mean intraocular pressure measured by rebound tonometry was 17.2 ±5.5 mmHg (n=46), and applanation tonometry resulted in statistically similar values (P=0.30; n=25). There was a significant variation in intraocular pressure throughout a 24-hour period (n=8). Fluorescein dye was not detected at the nostrils of any of the alpacas which underwent a Jones test to assess nasolacrimal duct patency (n=8).ConclusionThe ophthalmic findings appear largely consistent with previously published values from North America and continental Europe. Variations include the large range of measurements obtained and evidence of diurnal variation in intraocular pressure.

The study of wave propagation at different points in the arterial circulation may provide useful information regarding ventriculoarterial interactions. We describe a number of hemodynamic parameters in the carotid, brachial, and radial arteries of normal subjects by using noninvasive techniques and wave-intensity analysis (WIA). Twenty-one normal adult subjects (14 men and 7 women, mean age 44 ± 6 yr) underwent applanation tonometry and pulsed-wave Doppler studies of the right common carotid, brachial, and radial arteries. After ensemble averaging of the pressure and flow-velocity data, local hydraulic work was determined and a pressure-flow velocity loop was used to determine local wave speed. WIA was then applied to determine the magnitude, timings, and energies of individual waves. At all sites, forward-traveling (S) and backward-traveling (R) compression waves were observed in early systole. In mid- and late systole, forward-traveling expansion waves (X and D) were also seen. Wave speed was significantly higher in the brachial (6.97 ± 0.58 m/s) and radial (6.78 ± 0.62 m/s) arteries compared with the carotid artery (5.40 ± 0.34 m/s; P < 0.05). S-wave energy was greatest in the brachial artery (993.5 ± 87.8 mJ/m2), but R-wave energy was greatest in the radial artery (176.9 ± 19.9 mJ/m2). X-wave energy was significantly higher in the brachial and radial arteries (176.4 ± 32.7 and 163.2 ± 30.5 mJ/m2, respectively) compared with the carotid artery (41.0 ± 9.4 mJ/m2; P < 0.001). WIA illustrates important differences in wave patterns between peripheral arteries and may provide a method for understanding ventriculo-arterial interactions in the time domain.

The effects of simulated microgravity on the static and dynamic properties of large arteries are still mostly unknown. The present study evaluated, using an integrated vascular approach, changes in structure and function of the common carotid and femoral arteries (CCA and CFA) after prolonged head-down tilt bed rest (HDTBR). Ten healthy men were enrolled in a 5-week HDTBR study endorsed by the Italian Space Agency (ASI). Arterial geometry, flow, stiffness, and shear rate were evaluated by ultrasound. Local carotid pulse pressure and wave reflection were studied by applanation tonometry. After five weeks of HDTBR, CFA showed a decrease in lumen diameter without significant changes in wall thickness (IMT), resulting in an inward remodeling. Local carotid pulse pressure decreased and carotid-to-brachial pressure amplification increased. The ratio of systolic-to-diastolic volumetric flow in CFA decreased, whereas in CCA it tended to increase. Indices of arterial stiffness and shear rate did not change during HDTBR, either in CCA or CFA. In summary, prolonged HDTBR has a different impact on CCA and CFA structure and flow, probably depending on the characteristics of the vascular bed perfused.

Background. Obesity and low cardiorespiratory fitness (CRF) have been shown to independently increase the risk of CVD mortality. The aim of this study was to investigate the relationship between CRF, body fatness and markers of arterial function.Method and Results. Obese (9 male, 18 female; BMI 35.3 ± 0.9 kg·m-2) and lean (8 male, 18 female; BMI 22.5 ± 0.3 kg·m-2) volunteers were assessed for body composition (DXA), cardiorespiratory fitness (predicted max), blood pressure (BP), endothelial vasodilatator function (FMD), and arterial compliance (AC) (via radial artery tonometry). The obese group had more whole body fat and abdominal fat (43.5 ± 1.2% versus 27.2 ± 1.6%; and 48.6 ± 0.9% versus 28.9 ± 1.8%; resp.), and lower FMD (3.2 ± 0.4% versus 5.7 ± 0.7%; ) than the lean subjects, but there was no difference in AC. AC in large arteries was positively associated with CRF (; ) but not with fatness.Conclusion. These results indicate distinct influences of obesity and CRF on blood vessel health. FMD was impaired with obesity, which may contribute to arterial and metabolic dysfunction. Low CRF was associated with reduced elasticity in large arteries, which could result in augmentation of aortic afterload.

Aim: to evaluate the effect of renal denervation (RDN) on the stiffness of the aorta and major arteries, central blood pressure and index augmentation in patients with resistant hypertension. Material and methods. We included 20 patients with systolic blood pressure 178 [170; 180] mm Hg and diastolic blood pressure 100 [94; 100] mm Hg on 5.1±0.7 antihypertensive drugs with diuretic, who underwent bilateral RDN. Blood pressure (BP) was studied before intervention, at 7 days and 6 months after RDN by tree methods: office BP, 24-hour ambulatory blood pressure (ABPM) and aortic BP with applanation tonometry a. radialis (SphygmoCor). All patients were divided into two groups by ABPM in 6 months after RDN: responders (decrease of mean ABPM≥5 mm Hg) and non-responders (decrease of mean ABPM

La valutazione del bilancio tra l'apporto e la domanda di ossigeno nel miocardio è utile per predire e diagnosticare l'ischemia miocardica e l'infarto miocardico di tipo 2, condizioni che rappresentano una parte crescente del carico sanitario delle malattie cardiovascolari e la cui incidenza è in rapido aumento a causa dell’invecchiamento. Nella sua valutazione originale, ottenuta mediante registrazioni invasive, questo equilibrio è calcolato come il rapporto tra l'apporto di ossigeno, definito come l'area tra la pressione aortica e quella ventricolare sinistra durante la diastole (indice diastolico di pressione-tempo) e il consumo di ossigeno, definito come l'area sotto la curva di pressione durante la sistole (indice sistolico di pressione-tempo). Questo rapporto è chiamato SEVR (Subendocardial Viability Ratio) e può anche essere calcolato dall'analisi dell'onda di pressione centrale ottenuta non-invasivamente dalla tonometria arteriosa carotidea, dividendo le aree tra le curve di pressione diastolica e sistolica. La valutazione non invasiva convenzionale del SEVR mediante tonometria arteriosa è influenzata da alcune limitazioni metodologiche, che sono l'esclusione dal calcolo del tempo di contrazione isovolumetrico nell'indice sistolico pressione-tempo e l'esclusione della pressione diastolica ventricolare sinistra dall'indice diastolico pressione-tempo. Inoltre, la calibrazione dell'onda di pressione centrale derivata dalla tonometria carotidea può essere influenzata dal modo di calcolare la pressione arteriosa media dalla pressione arteriosa brachiale, che è necessaria per scalare la forma d'onda centrale. Questa tesi presenta una serie di studi volti a superare queste limitazioni, al fine di elaborare una forma corretta del SEVR e di validarlo contro la sua controparte invasiva e come un predittore clinico. Viene presentata una metodologia per calcolare in modo affidabile gli intervalli di tempo sistolico (tempo di contrazione isovolumetrica e periodo pre-eiettivo) da tonometria arteriosa con ECG, eseguita a livello carotideo e femorale, e viene quindi applicata in soggetti con o senza malattia cardiovascolare. È stata quindi affrontata la questione del calcolo della pressione arteriosa media dalla pressione arteriosa brachiale, in quanto è stata evidenziata una considerevole variabilità interindividuale e intraindividuale nel fattore di forma della pressione brachiale, nella popolazione generale di diverse età e nei pazienti ipertesi. L'approccio migliore per la calibrazione della pressione centrale non invasiva risiede nell'integrazione delle forme d'onda di pressione o, quando non applicabile, nell'uso di un algoritmo appropriato per il calcolo del fattore di forma brachiale. È stata quindi dimostrata una buona correlazione del SEVR determinato in modo invasivo, in pazienti sottoposti a cateterismo cardiaco, con il nuovo SEVR non invasivo calcolato mediante tonometria arteriosa e corretto considerando i tempi sistolici e la pressione diastolica ventricolare sinistra. Un'equazione per la stima della pressione diastolica ventricolare sinistra è stata derivata da parametri non invasivi della tonometria arteriosa e dai dati invasivi. Il nuovo SEVR è stato infine applicato nella coorte PARTAGE, un ampio studio di popolazione di individui di età maggiore di 80 anni. SEVR è risultato essere un predittore indipendente della mortalità totale nei soggetti anziani. In questa popolazione si può considerare un valore soglia di 100 per il SEVR. In sintesi, è stata creata e validata clinicamente una nuova formulazione di un indice (SEVR) per la valutazione del bilancio tra domanda e offerta di ossigeno al miocardio, ottenibile mediante tonometria arteriosa non invasiva.
The evaluation of the balance between oxygen supply and demand in the myocardium is useful for predicting and diagnosing myocardial ischemia and type-2 myocardial infarction, conditions that represent a growing part of the health burden of cardiovascular disease, and whose incidence is rapidly increasing due to an ageing population. In its original assessment by invasive registrations, this balance is calculated as the ratio between the oxygen supply, defined as the area between the aortic and left ventricular pressures during diastole (diastolic pressure-time index), and the oxygen consumption, defined as the area under the pressure curve during systole (systolic pressure-time index). This ratio is called SEVR (Subendocardial Viability Ratio) and may also be calculated from the analysis of the non-invasively determined central pressure wave obtained by carotid arterial tonometry, by dividing areas between the diastolic and systolic pressure curves. The conventional non-invasive assessment of SEVR by arterial tonometry is affected by some methodological limitations, that are the exclusion from the calculation of isovolumetric systolic time in the systolic pressure-time index and the exclusion of left ventricular diastolic pressure from diastolic pressure-time index. Moreover, the calibration of central pressure wave derived from carotid tonometry can be affected by the way of calculating mean arterial pressure from brachial cuff blood pressure, which is necessary for scaling the central waveform. This thesis presents a series of studies conducted to overcome the limitations mentioned above, in order to elaborate a corrected form of the SEVR and to validate it against its invasive counterpart and as a clinical predictor. A methodology to reliably calculate the systolic-time intervals (isovolumetric ejection time and pre-ejection period) from ECG-gated arterial tonometry performed at the carotid and femoral levels, is presented and applied in subjects with or without cardiovascular disease. The issue of calculation of mean arterial pressure from brachial cuff blood pressure was then addressed, as a considerable interindividual and intraindividual variability in brachial pressure form-factor was evidenced in general population of different ages and in hypertensive patients. The best approach for calibration of non-invasive central blood pressure waveform resides in the integration of pressure waveforms, or, when not applicable, in the use of an appropriate algorithm for calculation of brachial form factor. A good correlation of the invasively determined SEVR, in patients undergoing cardiac catheterization, was then demonstrated with the new non-invasive SEVR calculated by arterial tonometry and corrected by considering systolic time intervals and the left ventricular diastolic pressure. An equation for the estimation of left ventricular diastolic pressure was derived from non-invasive parameters of arterial tonometry and the invasive data. The new SEVR was finally applied in the PARTAGE cohort, a large population study of individuals 80 years of age and older living in nursing homes. SEVR was found to be an independent predictor of total mortality in the elderly subjects. A threshold value for SEVR of 100 may be considered in this population. In summary, a new formulation of an index (SEVR) for the evaluation of myocardial supply-demand balance from non-invasive arterial tonometry was created and clinically validated.

La misurazione della pressione arteriosa è molto comune nella pratica clinica poichè permette di avere una valutazione generale sullo stato di salute del paziente. La pressione arteriosa viene rilevata sia nei controlli di routine che nell'assistenza di un paziente in area critica. La misurazione può essere non invasiva oppure invasiva. La tecnica invasiva consiste nella rilevazione della pressione arteriosa tramite catetere. Il monitoraggio può avvenire tramite sensore extravascolare oppure intravascolare. I metodi non invasivi invece, permettono di valutare in maniera indiretta e ad intervalli regolari, i valori pressori, basondosi sulle intuizioni di Riva-Rocci e Korotkoff. La debolezza di queste tecniche non invasive risiede nell’impossibilità di tracciare la variabilità e la forma d’onda della pressione arteriosa. L’esigenza di avere una rilevazione non invasiva continua ha quindi spinto nel corso degli anni i ricercatori a sviluppare nuovi metodi di misura. Lo scopo delle nuove tecniche e dei miglioramenti di quelle più tradizionali resta comunque lo stesso: raggiungere l’accuratezza e la precisione della misurazione diretta, restando ovviamente non invasive.

Patients with peripheral arterial disease (PAD) have compromised blood flow to their extremities as a result of arterial narrowing. PAD is often associated with impairment in endothelial function which is exaggerated by injury from processes related to cardiovascular risk factors such as ageing, hypertension, hyperlipidemia, diabetes, smoking, and obesity [1]. Furthermore, patients with diabetes often have calcified arteries making standard non-invasive testing non diagnostic [2]. With increase in diabetes prevalence and concomitant PAD, a new non-invasive assessment method of arterial function that has the potential to reflect both arterial tone and response to ischemia reperfusion may be valuable. We have developed a peripheral arterial tonometry (PAT) system (previously described, [3]) that is capable of measuring pulsatility in peripheral digits. We complemented our system with simultaneous peripheral temperature measurements that could not only add value in understanding PAD, but also aid in clinical diagnoses. In this investigation, we characterized our system on healthy individuals before using it on patients suffering from arterial disease in future investigations.

Dynamic arterial blood pressure and blood flow are key determinants of normal or pathological functioning of the cardiovascular system. The measurement of these variables at multiple locations in the body is clinically and physiologically valuable, but difficult to achieve except with invasive methods which carry significant risk to the patient. We have developed and here present a computational model of systemic arterial hemodynamics. The model predicts dynamic pressures and flows throughout the systemic arterial vascular bed. The inputs to the model are pressure or flow measured at a single site, and a description of the architectural and mechanical properties of the blood and blood vessels. We have also measured dynamic pressure and flow noninvasively in healthy women and men. We use these measurements to test and refine the model. The arterial model includes over 24 million blood vessels. The dimensions and branching patterns of 45 large arteries are derived from population averages. Approximately half of these vessels terminate in self-similar branching networks of arteries which extend to capillary-sized vessels. Womersley’s linearization of the Navier-Stokes equations is used to describe the relationship between pressure and flow in each vessel. The inviscid wave velocity in each vessel is estimated based on the combined effects of Young’s modulus, vessel thickness and diameter, and the rheological properties of blood. The blood is modeled as a non-Newtonian fluid whose hematocrit and viscosity vary with vessel size. Wave reflections are computed at all junctions between vessels. The nonlinear pressure drop occurring at the bifurcation of each vessel into daughter vessels is estimated and taken into account when computing the pressures and flows throughout the network. Dynamic pressure is measured noninvasively by applanation tonometry. Dynamic blood velocity is measured with Doppler ultrasonography, and vessel diameter is measured using ultrasound. Custom software uses the electrocardiogram to average data from multiple beats to create ensemble average waveforms for pressure, velocity, and diameter. Data has been collected from the radial and carotid arteries. The experimentally measured pressure from one site is used as input to the model. The model predictions are compared to the other experimental measurements. Blood vessel mechanical properties are estimated by adjusting the model parameters to get good agreement between measured and predicted quantities. This capability can be used to understand effects of pathological changes in vascular properties on local pressure and flow behavior throughout the vasculature.