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Proceedings ArticleDOI

Local Evaluation of Variation in Pulse Wave Velocity over the Cardiac Cycle using Single-Element Ultrasound Transducer

01 Jul 2018-Vol. 2018, pp 4560-4563
TL;DR: Study results demonstrated that the proposed approach has a potential to provide valuable surrogate markers for cardiovascular risk assessment and is validated on a cohort of 15 subjects that includes normotensives and hypertensives.
Abstract: A method and system for single-site measurement of local pulse wave velocity (PWV) and its variation over the cardiac cycle are presented. The proposed system employs a single-element ultrasound transducer and associated custom technology to record arterial diameter and wall thickness waveforms in real-time. Simultaneously acquired blood pressure, diameter and wall thickness parameters were used to evaluate diastolic local PWV (CD) and systolic local PWV (Cs) from an arterial site of interest. The developed prototype system was validated on a cohort of 15 subjects (age $=43\pm 12$ years) that includes normotensives and hypertensives. Cs and CD measurements were obtained from the left carotid artery. A significant difference between carotid Cs and CD $(\Delta \mathrm{C})$ was observed in all recruited subjects (group average $\Delta \mathrm{C} = 0.92\pm 0.76\mathrm{m}/\mathrm{s})$, illustrating the arterial pressure dependency of local PWV. The absolute values of Cs and CD were within a range of 3.39 m/s to 7.5 m/s and 3.12 m/s to 5.82 m/s respectively. Normotensive versus hypertensive group-wise analysis was performed to investigate the degree of variation in the carotid local PWV over a cardiac cycle among different BP categories. Study results demonstrated that the proposed approach has a potential to provide valuable surrogate markers for cardiovascular risk assessment.
Citations
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Journal ArticleDOI
TL;DR: This paper enumerates all major local PWV measurement methods while pinpointing their salient methodological considerations and emphasizing the necessity of global standardization.
Abstract: Local pulse wave velocity (PWV) is evolving as one of the important determinants of arterial hemodynamics, localized vessel stiffening associated with several pathologies, and a host of other cardiovascular events. Although PWV was introduced over a century ago, only in recent decades, due to various technological advancements, has emphasis been directed toward its measurement from a single arterial section or from piecewise segments of a target arterial section. This emerging worldwide trend in the exploration of instrumental solutions for local PWV measurement has produced several invasive and noninvasive methods. As of yet, however, a univocal opinion on the ideal measurement method has not emerged. Neither have there been extensive comparative studies on the accuracy of the available methods. Recognizing this reality, makes apparent the need to establish guideline-recommended standards for the measurement methods and reference values, without which clinical application cannot be pursued. This paper enumerates all major local PWV measurement methods while pinpointing their salient methodological considerations and emphasizing the necessity of global standardization. Further, a summary of the advancements in measuring modalities and clinical applications is provided. Additionally, a detailed discussion on the minimally explored concept of incremental local PWV is presented along with suggestions of future research questions.

88 citations

Book ChapterDOI
29 Jul 2011

23 citations

Journal ArticleDOI

1 citations

References
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Book ChapterDOI
01 Jan 1983
TL;DR: The best documented driving force in the evolution of the vertebrate cardiovascular functions is the need for an efficient transport of respiratory gases between the gas exchanger (skin, gill, lung) and the tissues.
Abstract: Profound changes in the demands on the circulatory system have occurred during the evolution of the vertebrates from the aquatic forms to the more advanced terrestrial forms. These changes reflect a variety of anatomical and functional alterations, and also the adjustment from aquatic life at zero gravity to the demands of terrestrial life. The best documented driving force in the evolution of the vertebrate cardiovascular functions is the need for an efficient transport of respiratory gases between the gas exchanger (skin, gill, lung) and the tissues (Johansen and Burggren 1980, Johansen 1982).

335 citations

Journal ArticleDOI
TL;DR: The great challenge is to explore the new instrumental solutions that allow the PWV assessment with fewer approximations for an accurately evaluation and relatively inexpensive techniques in order to be used in the clinical routine.
Abstract: The great incidence of cardiovascular (CV) diseases in the world spurs the search for new solutions to enable an early detection of pathological processes and provides more precise diagnosis based in multi-parameters assessment. The pulse wave velocity (PWV) is considered one of the most important clinical parameters for evaluate the CV risk, vascular adaptation, and therapeutic efficacy. Several studies were dedicated to find the relationship between PWV measurement and pathological status in different diseases, and proved the relevance of this parameter. The commercial devices dedicate to PWV estimation make a regional assessment (measured between two vessels), however a local measurement is more precise evaluation of artery condition, taking into account the differences in the structure of arteries. Moreover, the current devices present some limitations due to the contact nature. Emerging trends in CV monitoring are moving away from more invasive technologies to non-invasive and non-contact solutions. The great challenge is to explore the new instrumental solutions that allow the PWV assessment with fewer approximations for an accurately evaluation and relatively inexpensive techniques in order to be used in the clinical routine.

214 citations


"Local Evaluation of Variation in Pu..." refers background in this paper

  • ...It is a vital clinical parameter for prediction of future cardiovascular risks and outcomes, evaluation of vascular aging of central arteries, local assessment of vascular adaption and therapeutic efficiency [1], and cuffless blood pressure (BP) estimation from specific arteries [2]....

    [...]

Journal ArticleDOI
TL;DR: CMR with in-plane velocity-encoded cardiovascular magnetic resonance is the optimal approach for studying Bramwell-Hill associations between local PWV and aortic distensibility and this approach enables non-invasive estimation of local pulse pressure anddistensibility.
Abstract: The Bramwell-Hill model describes the relation between vascular wall stiffness expressed in aortic distensibility and the pulse wave velocity (PWV), which is the propagation speed of the systolic pressure wave through the aorta. The main objective of this study was to test the validity of this model locally in the aorta by using PWV-assessments based on in-plane velocity-encoded cardiovascular magnetic resonance (CMR), with invasive pressure measurements serving as the gold standard. Seventeen patients (14 male, 3 female, mean age ± standard deviation = 57 ± 9 years) awaiting cardiac catheterization were prospectively included. During catheterization, intra-arterial pressure measurements were obtained in the aorta at multiple locations 5.8 cm apart. PWV was determined regionally over the aortic arch and locally in the proximal descending aorta. Subsequently, patients underwent a CMR examination to measure aortic PWV and aortic distention. Distensibility was determined locally from the aortic distension at the proximal descending aorta and the pulse pressure measured invasively during catheterization and non-invasively from brachial cuff-assessment. PWV was determined regionally in the aortic arch using through-plane and in-plane velocity-encoded CMR, and locally at the proximal descending aorta using in-plane velocity-encoded CMR. Validity of the Bramwell-Hill model was tested by evaluating associations between distensibility and PWV. Also, theoretical PWV was calculated from distensibility measurements and compared with pressure-assessed PWV. In-plane velocity-encoded CMR provides stronger correlation (p = 0.02) between CMR and pressure-assessed PWV than through-plane velocity-encoded CMR (r = 0.69 versus r = 0.26), with a non-significant mean error of 0.2 ± 1.6 m/s for in-plane versus a significant (p = 0.006) error of 1.3 ± 1.7 m/s for through-plane velocity-encoded CMR. The Bramwell-Hill model shows a significantly (p = 0.01) stronger association between distensibility and PWV for local assessment (r = 0.8) than for regional assessment (r = 0.7), both for CMR and for pressure-assessed PWV. Theoretical PWV is strongly correlated (r = 0.8) with pressure-assessed PWV, with a statistically significant (p = 0.04) mean underestimation of 0.6 ± 1.1 m/s. This theoretical PWV-estimation is more accurate when invasively-assessed pulse pressure is used instead of brachial cuff-assessment (p = 0.03). CMR with in-plane velocity-encoding is the optimal approach for studying Bramwell-Hill associations between local PWV and aortic distensibility. This approach enables non-invasive estimation of local pulse pressure and distensibility.

64 citations


"Local Evaluation of Variation in Pu..." refers background in this paper

  • ...By considering the relative change in A(P) over local ΔP, the value of κ|P→Ps can be approximated for the PS to PD range as κ = ∆A (AD ∆P) ⁄ [9]; ∆A = (AS − AD), where AD and AS are the luminal area at diastolic and systolic pressure level respectively....

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Journal ArticleDOI
TL;DR: The feasibility of the novel ARTSENS device in performing accurate in vivo measurements of arterial stiffness is verified, a device for image free, noninvasive, automated evaluation of vascular stiffness amenable for field use.
Abstract: Vascular stiffness is an indicator of cardiovascular health, with carotid artery stiffness having established correlation to coronary heart disease and utility in cardiovascular diagnosis and screening. State of art equipment for stiffness evaluation are expensive, require expertise to operate and not amenable for field deployment. In this context, we developed ARTerial Stiffness Evaluation for Noninvasive Screening (ARTSENS), a device for image free, noninvasive, automated evaluation of vascular stiffness amenable for field use. ARTSENS has a frugal hardware design, utilizing a single ultrasound transducer to interrogate the carotid artery, integrated with robust algorithms that extract arterial dimensions and compute clinically accepted measures of arterial stiffness. The ability of ARTSENS to measure vascular stiffness in vivo was validated by performing measurements on 125 subjects. The accuracy of results was verified with the state-of-the-art ultrasound imaging-based echo-tracking system. The relation between arterial stiffness measurements performed in sitting posture for ARTSENS measurement and sitting/supine postures for imaging system was also investigated to examine feasibility of performing ARTSENS measurements in the sitting posture for field deployment. This paper verified the feasibility of the novel ARTSENS device in performing accurate in vivo measurements of arterial stiffness. As a portable device that performs automated measurement of carotid artery stiffness with minimal operator input, ARTSENS has strong potential for use in large-scale screening.

53 citations


"Local Evaluation of Variation in Pu..." refers methods in this paper

  • ...The proposed approach was realized using our clinically validated ARTSENS technology [6]....

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Journal ArticleDOI
TL;DR: A novel photoplethysmograph probe employing dual photodiodes excited using a single infrared light source was developed for local pulse wave velocity (PWV) measurement and the potential use of the proposed system in cuffless blood pressure techniques was demonstrated.
Abstract: Objective: A novel photoplethysmograph probe employing dual photodiodes excited using a single infrared light source was developed for local pulse wave velocity (PWV) measurement. The potential use of the proposed system in cuffless blood pressure (BP) techniques was demonstrated. Approach: Initial validation measurements were performed on a phantom using a reference method. Further, an in vivo study was carried out in 35 volunteers (age = 28 ± 4.5 years). The carotid local PWV, carotid to finger pulse transit time (PTTR) and pulse arrival time at the carotid artery (PATC) were simultaneously measured. Beat-by-beat variation of the local PWV due to BP changes was studied during post-exercise relaxation. The cuffless BP estimation accuracy of local PWV, PATC, and PTTR was investigated based on inter- and intra-subject models with best-case calibration. Main results: The accuracy of the proposed system, hardware inter-channel delay (<0.1 ms), repeatability (beat-to-beat variation = 4.15%–11.38%) and reproducibility of measurement (r = 0.96) were examined. For the phantom experiment, the measured PWV values did not differ by more than 0.74 m s−1 compared to the reference PWV. Better correlation was observed between brachial BP parameters versus local PWV (r = 0.74–0.78) compared to PTTR (|r| = 0.62–0.67) and PATC (|r| = 0.52–0.68). Cuffless BP estimation using local PWV was better than PTTR and PATC with population-specific models. More accurate estimates of arterial BP levels were achieved using local PWV via subject-specific models (root-mean-square error ≤2.61 mmHg). Significance: A reliable system for cuffless BP measurement and local estimation of arterial wall properties.

53 citations


"Local Evaluation of Variation in Pu..." refers background in this paper

  • ...It is a vital clinical parameter for prediction of future cardiovascular risks and outcomes, evaluation of vascular aging of central arteries, local assessment of vascular adaption and therapeutic efficiency [1], and cuffless blood pressure (BP) estimation from specific arteries [2]....

    [...]