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Arathy R

Bio: Arathy R is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Pulse wave velocity & Hydrostatic pressure. The author has an hindex of 2, co-authored 7 publications receiving 9 citations.

Papers
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Proceedings ArticleDOI
01 May 2017
TL;DR: In-vivo validation study promising the potential use of the developed accelerometer probe for cuffless evaluation of BP parameters and heartrate as a confounder of local PWV assessment was obtained.
Abstract: The velocity of propagation of arterial blood pulse signals obtained from a smaller arterial section referred as local pulse wave velocity (PWV) is an index of cardiovascular events of a particular artery. In this work, we introduce a novel design of accelerometer probe for local PWV measurement from the carotid artery. The proposed probe was developed using highly sensitive dual MEMS accelerometers. The probe design with tiny dual element sensors was capable of simultaneously acquiring acceleration signals generated due to arterial wall displacement towards the skin surface. Measurements were performed from carotid artery over a smaller arterial section of length 24 mm. The ability of the probe to acquire continuous arterial waveforms and cycle-to-cycle local PWV measurement was verified by conducting an in-vivo test in multiple subjects (11 volunteers aged between 20 – 60 years) under controlled settings. Reliable as well as repeatable signals (maximum beat-to-beat variation was less than 13%) and carotid PWV measurement with high reproducibility was obtained. A correlation examination of the local PWV with heartrate and BP was conducted during the same study. A statistically significant correlation was observed with the correlation coefficient greater than 0.78 for BP parameters and 0.66 for heartrate. In-vivo validation study promising the potential use of the developed accelerometer probe for cuffless evaluation of BP parameters and heartrate as a confounder of local PWV assessment was obtained.

6 citations

Proceedings ArticleDOI
01 Jul 2018
TL;DR: An accelerometric patch probe with two microelectromechanical accelerometer sensors for local pulse wave velocity (PWV) measurement from the carotid artery is demonstrated and the potential application of the developed dual-accelerometric system in non-invasive, continuous cuffless BP measurement techniques is illustrated.
Abstract: In this work, we demonstrate an accelerometric patch probe with two microelectromechanical accelerometer sensors for local pulse wave velocity (PWV) measurement from the carotid artery. Dual acceleration plethysmogram (APG) signals were acquired from a small section of the artery by keeping the sensors at 32 mm apart. A custom analog front-end circuit (inter-channel delay $< 0.15$ ms) was used for reliable signal acquisition. Simultaneously acquired dual APG signals were processed in real-time and local PWV was evaluated in a beat-by-beat manner. A transversal study on a cohort of 15 volunteers (4 males, 11 females, mean age = $25.6 \pm 1.92$ years) was conducted to validate the developed prototype system. During the study, carotid local PWV and brachial blood pressure (BP) parameters were recorded from both sitting and standing posture. The absolute values of measured carotid local PWV were in the range of 3 m/s – 4.2 m/s (beat-to-beat variation $=$ 2.61% – 13.07%). Measured local PWV values significantly correlated with brachial systolic BP ($\textbf{R}^{\mathbf {2}} =$ 0.87) and diastolic BP ($\textbf{R}_{\mathbf {\, }}^{\mathbf {2}} \quad =$ 0.79). Logarithmic functions provided the best monotonic model for carotid local PWV versus brachial BP parameters for the recorded data points. The developed population-specific mathematical models were then used for cuffless evaluation of BP parameters from carotid local PWV. The root-mean-square error in the estimated systolic and diastolic pressure was 7.53 mmHg and 6.0 mmHg respectively. Study results illustrate the potential application of the developed dual-accelerometric system in non-invasive, continuous cuffless BP measurement techniques.

2 citations

Proceedings ArticleDOI
01 Jul 2019
TL;DR: The experimental validation study results exhibit the feasibility of using the developed accelerometer system for continuous carotid distension and lumen diameter measurements, whereby the estimation of carotids arterial stiffness is estimated.
Abstract: We present a system with an accelerometer patch probe design for non-invasive evaluation of carotid arterial stiffness. The proposed system could continuously measure the acceleration signal derived due to the propagation of blood pulse wave through the left carotid artery, double integrating and scaling it to estimate the accelerometer-derived carotid wall displacement. This functional principle was proved by comparing the accelerometer-derived carotid wall displacement with the carotid distension signal from the reference system ARTSENS® (ARTerial Stiffness Evaluation for Noninvasive Screening device) for all the recruited human subjects. Assuming the relationship to be linear, a one-time subject-specific calibration was performed with the simultaneously acquired reference distension signal and the accelerometer-derived carotid displacement signals on its anachrotic limbs data points (at systolic phases) for each subject. This calibration equation was tested with latterly acquired accelerometer signals and results in the measurement of accelerometer-derived carotid distension and lumen-diameter values. The ability of the accelerometer system to measure real-time carotid distension and lumen diameter in a repeatable beat-by-beat manner for arterial stiffness index evaluation was validated in-vivo. The accuracy of the obtained results was studied with our clinically validated reference system. The experimental validation study results exhibit the feasibility of using the developed accelerometer system for continuous carotid distension and lumen diameter measurements, whereby the estimation of carotid arterial stiffness.

1 citations

Proceedings ArticleDOI
11 Jun 2018
TL;DR: The developed accelerometer-based system could continuously capture the accelerations related to the displacement of the carotid arterial walls and could capture continuous distension waveforms for all the recruited subjects.
Abstract: The measure of arterial stiffness is significant for the diagnosis of the cardiovascular health. A prototype accelerometer- based system for vascular stiffness indices detection is proposed and experimentally validated. The developed accelerometer-based system could continuously capture the accelerations related to the displacement of the carotid arterial walls. The measured accelerometric waveforms are recorded by a data acquisition card for signal processing and analysis in real-time. The recorded accelerometric signals from the carotid skin surface are double- integrated and calibrated linearly using our clinically validated ARTSENS® (ARTerial Stiffness Evaluation for Noninvasive Screening) device to estimate the subject-specific one-time calibration coefficients. The acquired accelerometric signal with these calibration coefficients was used to estimate the diameter parameters such as arterial distension ($\Delta \textbf{D}$), end-diastolic diameter ($\textbf{D}_{\mathbf {d}}$), and systolic diameter ($\textbf{D}_{\mathbf {s}}$). 12 subjects (7 males, 5 females, age $=25.42\pm 2.5$ years) with no prior history of cardiovascular diseases were enrolled for the in-vivo validation study. The accelerometer-based system could capture continuous distension waveforms for all the recruited subjects. Arterial stiffness indices such as stiffness index (β), arterial compliance (AC) and Peterson's elastic modulus ($\textbf{E}_{\mathbf {p}}$) were calculated using the obtained diameter parameters from the accelerometer-based system. The correlation ($\textbf{R}^{\mathbf {2}}$) for β, AC and $\textbf{E}_{\mathbf {p}}$ observed between ARTSENS reference device and accelerometric system were 0.93, 0.95 and 0.94 respectively. Bland-Altman plots of β, AC, and $E_{\mathbf {p} }$ of ARTSENS reference device and the accelerometric system shows a small mean bias of 0.07, -0.001 and 0.81 respectively. The preliminary results suggest the potential of the accelerometer- based system for vascular wall stiffness indices detection.

1 citations

Proceedings ArticleDOI
01 Jul 2020
TL;DR: An accelerometric system with a custom-designed patch probe and signal acquisition hardware to acquire the carotid wall displacement from the soft tissue surface for arterial stiffness evaluation was developed and the results were found to be stable over a day, indicating the utility of the system for a reliable measure of non-invasive carotil stiffness.
Abstract: We have developed an accelerometric system with a custom-designed patch probe and signal acquisition hardware to acquire the carotid wall displacement from the soft tissue surface for arterial stiffness evaluation. A subject-specific calibration model was developed to estimate the morphology of accurate carotid diameter waveform, using a standard ultrasound B-mode imaging system as the reference. Following the one-time calibration, the accelerometric system continuously acquired a non-invasive carotid lumen diameter waveform. The capability of the accelerometric system to measure the carotid stiffness index (β) in-vivo was experimentally validated by performing measurements on 8 normotensive subjects in the supine position. The repeatability and reproducibility of the results were investigated and were found to be comparable to those provided by ultrasound imaging systems. Further, the variation of arterial stiffness index measurements on different days was studied to verify the ability of the system to give a stable measure of stiffness. The accuracy of the observed results was confirmed with the state-of-art B-mode ultrasound imaging system. The results were found to be stable over a day, indicating the utility of the system for a reliable measure of non-invasive carotid arterial stiffness.

Cited by
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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

Journal ArticleDOI
TL;DR: The feasibility of calibration-free, cuffless BP measurement at an arterial site of interest was demonstrated with a level of acceptable accuracy and the potential utility of the proposed method and system in hypertension screening and local evaluation of arterial stiffness indices was demonstrated.
Abstract: Objective: We propose a calibration-free method and system for cuffless blood pressure (BP) measurement from superficial arteries. A prototype device with bi-modal probe arrangement was designed and developed to estimate carotid BP – an indicator of central aortic pressure. Methods: Mathematical models relating BP parameters of an arterial segment to its dimensions and local pulse wave velocity (PWV) are introduced. A bi-modal probe utilizing ultrasound and photoplethysmograph sensors was developed and used to measure diameter values and local PWV from the carotid artery. Carotid BP was estimated using the measured physiological parameters without any subject- or population-specific calibration procedures. The proposed cuffless BP estimation method and system were tested for accuracy, usability, and for potential utility in hypertension screening, on a total of 83 subjects. Results: The prototype device demonstrated its capability of detecting beat-by-beat arterial dimensions and local PWV simultaneously. Carotid diastolic BP (DBP) and systolic BP (SBP) were estimated over multiple cardiac cycles in real-time. The absolute error in carotid DBP was Conclusion: The feasibility of calibration-free, cuffless BP measurement at an arterial site of interest was demonstrated with a level of acceptable accuracy. The study also demonstrated the potential utility of the proposed method and system in hypertension screening and local evaluation of arterial stiffness indices. Significance: Novel approach for calibration-free cuffless BP estimation; a potential tool for local BP measurement and hypertension screening.

60 citations

Proceedings ArticleDOI
01 Jul 2018
TL;DR: An accelerometric patch probe with two microelectromechanical accelerometer sensors for local pulse wave velocity (PWV) measurement from the carotid artery is demonstrated and the potential application of the developed dual-accelerometric system in non-invasive, continuous cuffless BP measurement techniques is illustrated.
Abstract: In this work, we demonstrate an accelerometric patch probe with two microelectromechanical accelerometer sensors for local pulse wave velocity (PWV) measurement from the carotid artery. Dual acceleration plethysmogram (APG) signals were acquired from a small section of the artery by keeping the sensors at 32 mm apart. A custom analog front-end circuit (inter-channel delay $< 0.15$ ms) was used for reliable signal acquisition. Simultaneously acquired dual APG signals were processed in real-time and local PWV was evaluated in a beat-by-beat manner. A transversal study on a cohort of 15 volunteers (4 males, 11 females, mean age = $25.6 \pm 1.92$ years) was conducted to validate the developed prototype system. During the study, carotid local PWV and brachial blood pressure (BP) parameters were recorded from both sitting and standing posture. The absolute values of measured carotid local PWV were in the range of 3 m/s – 4.2 m/s (beat-to-beat variation $=$ 2.61% – 13.07%). Measured local PWV values significantly correlated with brachial systolic BP ($\textbf{R}^{\mathbf {2}} =$ 0.87) and diastolic BP ($\textbf{R}_{\mathbf {\, }}^{\mathbf {2}} \quad =$ 0.79). Logarithmic functions provided the best monotonic model for carotid local PWV versus brachial BP parameters for the recorded data points. The developed population-specific mathematical models were then used for cuffless evaluation of BP parameters from carotid local PWV. The root-mean-square error in the estimated systolic and diastolic pressure was 7.53 mmHg and 6.0 mmHg respectively. Study results illustrate the potential application of the developed dual-accelerometric system in non-invasive, continuous cuffless BP measurement techniques.

2 citations

Book ChapterDOI
01 Jan 2021

1 citations