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Journal ArticleDOI

A Virtual Instrument for Automated Measurement of Arterial Compliance

01 Dec 2010-Journal of Medical Devices-transactions of The Asme (American Society of Mechanical Engineers)-Vol. 4, Iss: 4, pp 045004
TL;DR: A simple instrument for noninvasive in vivo evaluation of arterial compliance using a single element ultrasound transducer that can measure arterial distension with a precision better than 5 and the end-diastolic arterial diameter with an accuracy of 1%.
Abstract: Measurement of arterial distensibility is very important in cardiovascular diagnosis for early detection of coronary heart disease and possible prediction of future cardiac events. Conventionally, B-mode ultrasound imaging systems have been used along with expensive vessel wall tracking systems for estimation of arterial distension and calculation of various estimates of compliance. We present a simple instrument for noninvasive in vivo evaluation of arterial compliance using a single element ultrasound transducer. The measurement methodology is initially validated using a proof of concept pilot experiment using a commercial ultrasound pulser-receiver. A prototype system is then developed around a PXI chassis using LABVIEW software. The virtual instrument employs a dynamic threshold algorithm to identify the artery walls and then utilizes a correlation based tracking technique to estimate arterial distension. The end-diastolic echo signals are averaged to reduce error in the automated diameter measurement process. The instrument allows automated measurement of the various measures of arterial compliance with minimal operator intervention. The performance of the virtual instrument was first analyzed using simulated data sets to establish the maximum measurement accuracy achievable under different input signal to noise ratio (SNR) levels. The system could measure distension with accuracy better than 10 μm for positive SNR. The measurement error in diameter was less than 1%. The system was then thoroughly evaluated by the experiments conducted on phantom models of the carotid artery and the accuracy and resolution were found to meet the requirements of the application. Measurements performed on human volunteers indicate that the instrument can measure arterial distension with a precision better than 5%. The end-diastolic arterial diameter can be measured with a precision better than 2% and an accuracy of 1%. The measurement system could lead to the development of small, portable, and inexpensive equipment for estimation of arterial compliance suitable in mass screening of "at risk" patients. The automated compliance measurement algorithm implemented in the instrument requires minimal operator input. The instrument could pave the way for dedicated systems for arterial compliance evaluation targeted at the general medical practitioner who has little or no expertise in vascular ultrasonography.
Citations
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Proceedings ArticleDOI
01 Jan 2014
TL;DR: Stiffness measurements provided by ARTSENS were found to be stable over a day indicating utility of the instrument in providing a quick and reliable measure of carotid artery stiffness.
Abstract: Evaluation of arterial stiffness is significant in early detection and vascular diagnosis. We have developed and validated an image free system called ARTSENS for evaluation of carotid artery stiffness. In this paper, we present a detailed study on the repeatability of arterial stiffness measurements performed using ARTSENS. The study protocol was designed to emulate typical constraints encountered in field usage of ARTSENS as a screening tool. The intra operator variability (repeatability) of ARTSENS was verified by in-vivo measurements on 18 subjects. Inter operator variability (reproducibility) was also studied. The ability of the instrument to give reliable measurements in both sitting and supine posture of the subject was verified. Further, the variation of arterial stiffness measurements over different times of the day was investigated to verify the ability of the instrument to give a practically usable stable measure of stiffness. The repeatability and reproducibility of ARTSENS measurements was found to be comparable to those provided by state of art image-based systems. Stiffness measurements provided by ARTSENS were found to be stable over a day indicating utility of the instrument in providing a quick and reliable measure of carotid artery stiffness.

10 citations

Proceedings ArticleDOI
15 May 2016
TL;DR: Initial results indicate a strong potential of MPG - Ultrasound arterial compliance probe in continuous, cuffless evaluation of blood pressure (BP) from superficial arteries.
Abstract: Cardiovascular diseases are the leading cause of death around the world. Non-invasive estimation of arterial parameters is significant in the early detection of cardiovascular diseases. In this work, we present an arterial compliance probe for calibration-free evaluation of carotid pulse pressure. This novel cuffless measurement technique uses dual magnetic plethysmograph (MPG) transducers for carotid local pulse wave velocity (PWV) measurement and single element ultrasound transducer for measuring arterial dimensions. Proposed arterial compliance probe can acquire two blood pulse waveforms and arterial diameter parameters simultaneously, which are then utilized in cycle-to-cycle estimation of arterial local PWV and pulse pressure without any subject or population specific calibration. The design of compliance probe and measurement system was verified by in-vivo trials. Accurate local PWV measurement and calibration free estimation of carotid pulse pressure was also validated by in-vivo studies. Initial results indicate a strong potential of MPG — Ultrasound arterial compliance probe in continuous, cuffless evaluation of blood pressure (BP) from superficial arteries.

9 citations


Cites methods from "A Virtual Instrument for Automated ..."

  • ...We have already developed and successfully validated an image-free technology, ARTSENS® for automated evaluation of arterial dimensions using single-element ultrasound transducers [10]....

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Proceedings ArticleDOI
05 Nov 2015
TL;DR: Stiffness measurements made using ARTSENSTouch in sitting posture showed strong correlation with those obtained from the imaging system in supine posture, and the repeatability of ARTSENS measurements was also found to be satisfactory.
Abstract: Arterial stiffness is recognized as an independent risk factor for cardiovascular events and has potential in vascular screening. We have developed ‘ARTSENS®’, an image free system for evaluation of vascular stiffness. Here, we present ARTSENSTouch, a portable device for evaluation of carotid artery stiffness in field settings. A technical validation of the device in comparison with reference ultrasound imaging system is presented. The validation study emulated constraints faced in evaluation of stiffness in field, such as measurement in sitting posture, use of brachial blood pressure for computations, limited time available for testing and lack of electrical power supply for instrument. The usability of the device and its accuracy, with respect to the reference ultrasound imaging system, was verified by conducting in-vivo measurements on 30 subjects. Stiffness measurements made using ARTSENS in sitting posture showed strong correlation with those obtained from the imaging system in supine posture. The repeatability of ARTSENS measurements was also found to be satisfactory.

7 citations

Proceedings ArticleDOI
10 May 2011
TL;DR: In this paper, the authors presented a Virtual Instrument (VI) for automated estimation of both local and regional arterial compliance measures using an ultrasound transducer to measure the distension and lumen diameter of the carotid artery.
Abstract: The evaluation of arterial compliance is very important in cardiovascular screening of “at-risk” patients. Existing techniques for local arterial stiffness estimation put a premium on technology and operator expertise. Regional stiffness, measured in terms of the pulse wave velocity, is prone to errors in both path-length and delay estimation. Here, we present a Virtual Instrument (VI) for automated estimation of both local and regional arterial compliance measures. Local arterial compliance is evaluated by utilizing an ultrasound transducer to measure the distension and lumen diameter of the carotid artery. The regional stiffness is estimated from the pulse wave velocity, measured using two magnetic transducers in a dual-channel arrangement. The automated measurement algorithms are thoroughly analyzed, to identify and minimize possible error sources as well as to optimize the design of both the transducer and the virtual instrument. The results of a few human trials are also presented to illustrate the capability of the VI to measure arterial compliance in-vivo.

7 citations


Cites methods from "A Virtual Instrument for Automated ..."

  • ...A detailed explanation of this automated measurement algorithm has been reported in earlier works [5], [10]....

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  • ...The echoes from the artery walls are received by the same transducer and amplified and digitized using a PXI-5152 digitizer (National Instruments) at 100 MSa/s with 8-bit resolution [5]....

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Proceedings ArticleDOI
01 Dec 2014
TL;DR: An extension to the ARTSENS system to estimate the carotid arterial pressure (CAP) from the BAP, using the fact that mean and diastolic pressures at both arterial sites are the same as a surrogate for the CAP waveform.
Abstract: Over past few years our group has been developing ARTSENS®, a low-cost, portable and non-invasive tool for measurement of arterial stiffness (AS) AS of the common carotid artery (CCA) has high prognostic value in stratification of risk of contracting cardiovascular disease (CVD) in future ARTSENS uses a single element ultrasound transducer to obtain A-Mode frames from the CCA and processes them to obtain the diameter distension waveform For calculation of AS, any AS measurement system requires the pulse pressure in the artery under investigation In absence of reliable methods to estimate the carotid arterial pressure (CAP), in conventional AS measurement systems, the brachial arterial pressure (BAP) is used as a surrogate for the CAP to calculate the AS This can lead to large errors, as there can be large difference in systolic pressures at both sites, especially in young subjects In this paper we report an extension to the ARTSENS system to estimate the CAP from the BAP This uses the fact that mean and diastolic pressures at both arterial sites are the same We made the required hardware to obtain the systolic, mean and diastolic BAP We then use the diameter distension waveform, obtained by processing ultrasound frames from ARTSENS, as a surrogate for the CAP waveform which is scaled and shifted to obtain the CCA pulse pressure (CPP) BAP and CAP were estimated for 10 human subjects using the new system Bland-Altman analysis shows that ARTSENS is able to get BAP within acceptable limits of accuracy and pulse pressure is on an average 17 mmHg lower in CCA compared to the brachial artery which is in consonance with findings by other investigators

6 citations

References
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Journal ArticleDOI
01 Feb 2001-Stroke
TL;DR: This population-based study shows that arterial stiffness is strongly associated with atherosclerosis at various sites in the vascular tree.
Abstract: Background and Purpose—Studies of the association between arterial stiffness and atherosclerosis are contradictory. We studied stiffness of the aorta and the common carotid artery in relation to se...

1,134 citations

Journal ArticleDOI
TL;DR: The effects of current and future cardiovascular drugs on arterial stiffness are discussed, as is the relationship between arterial elasticity and endothelial function.
Abstract: Investigation of arterial stiffness, especially of the large arteries, has gathered pace in recent years with the development of readily available noninvasive assessment techniques. These include the measurement of pulse wave velocity, the use of ultrasound to relate the change in diameter or area of an artery to distending pressure, and analysis of arterial waveforms obtained by applanation tonometry. Here, we describe each of these techniques and their limitations and discuss how the measured parameters relate to established cardiovascular risk factors and clinical outcome. We also consider which techniques might be most appropriate for wider clinical application. Finally, the effects of current and future cardiovascular drugs on arterial stiffness are also discussed, as is the relationship between arterial elasticity and endothelial function.

813 citations

Journal ArticleDOI
P.C.G. Simons1, A. Algra1, M. L. Bots1, D. E. Grobbee1, Y. van der Graaf1 
TL;DR: Common carotid IMT anddistensibility are clear markers of cardiovascular risk in patients who already have vascular disease or atherosclerotic risk factors and IMT appears to discriminate between low- and high-risk patients better than distensibility.
Abstract: Background—Common carotid intima-media thickness (IMT) and distensibility are markers of structural and functional vessel wall properties. Both parameters have been found in population-based studies to be associated with cardiovascular risk factors and prevalent cardiovascular disease. We investigated cross-sectionally whether IMT and distensibility are associated with cardiovascular risk in patients who already have vascular disease or atherosclerotic risk factors and evaluated the diagnostic ability of IMT and distensibility to discriminate between low- and high-risk patients. Methods and Results—IMT and distensibility (change of diameter) of the left and right common carotid arteries were measured in the first 570 patients (537 for distensibility) enrolled in the Second Manifestations of ARTerial disease (SMART) study, a cohort study among patients with a manifestation of vascular disease or cardiovascular risk factors. Three risk scores were used to classify each patient’s vascular risk. Areas under t...

378 citations

Journal ArticleDOI
TL;DR: An overview of time-domain techniques that have appeared in the literature over the past few years is presented, and their potential advantages over Doppler are examined, and the individual techniques are compared.
Abstract: The Doppler technique has traditionally been the method used to extract motion information from ultrasonic echoes reflected by moving tissues. The Doppler technique has been around for a long time, and has been extensively reviewed and analyzed in the literature. Recently, time-domain methodologies for estimating tissue motion have gained in popularity. Time-domain methods have advantages over Doppler methods in many applications, and as of yet have not been comprehensively reviewed. An overview of time-domain techniques that have appeared in the literature over the past few years is presented. Their potential advantages over Doppler are examined, and the individual techniques are compared. >

340 citations

Journal ArticleDOI
TL;DR: Under controlled experimental conditions there was good repeatability of measurements of indices between sessions of both intrinsic and functional arterial mechanical properties (central and carotid arterial compliance, intima-media thickness and brachial flow-mediated dilation).
Abstract: 1. Repeatability of measurements of arterial compliance and flow-mediated dilation of the brachial artery has been infrequently reported, despite increasing use in interventional and risk-factor modification studies. Furthermore, little is known about the interrelationships of the various indices. The purposes of this study were to determine the repeatability and interrelationships of a range of arterial indices.2. Fifty healthy volunteers, 20 men and 30 women, aged 20-70 (mean 46.5) years, were studied on two occasions, using an identical protocol, at a mean interval of 2.5 weeks. Tonometry, ultrasound and Doppler technique were used to measure the following: carotid wall intima-media thickness (IMT), total systemic artery compliance (SAC), arterial pulse wave velocity [PWV aorto-femoral (A-F), and femoral-dorsalis pedis (F-D)], carotid distensibility coefficient (DC) and carotid augmentation index (AI). Brachial flow-mediated dilation was measured in 30 subjects with analysis of diameter change for 4 min post ischaemia.3. There were no systematic differences over the observed range of measurements for any of the reported parameters. Coefficients of variation were as follows: IMT 2.8%, SAC 9.2%, PWV(A-F) 3.2%, PWV(F-D) 5.0%, DC 10.0%, AI 1.3%. Brachial flow-mediated dilation curves were not different between visits; changes were maximum 60-s post ischaemia. All indices of arterial compliance were significantly correlated with age. The three different indices of central arterial compliance [SAC, PWV(A-F) and AI] were significantly correlated with carotid intima-media thickness.4. Under controlled experimental conditions there was good repeatability of measurements of indices between sessions of both intrinsic and functional arterial mechanical properties (central and carotid arterial compliance, intima-media thickness and brachial flow-mediated dilation). Sample size tables for clinical trials using these indices are presented.

316 citations