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2,186 results on '"Lovell, Nigel H."'

152. Noninvasive average flow and differential pressure estimation for an implantable rotary blood pump using dimensional analysis

Author

Lim, Einly, Karantonis, Dean M., Reizes, John A., Cloherty, Shaun L., Mason, David G., and Lovell, Nigel H.

Subjects
Dimensional analysis -- Methods, Hemodynamics -- Research, Blood flow -- Measurement, Blood flow -- Methods, Biological sciences, Business, Computers, Health care industry
Abstract

Accurate noninvasive average flow and differential pressure estimation of implantable rotary blood pumps (IRBPs) is an important practical element for their physiological control. While most attempts at developing flow and differential pressure estimate models have involved purely empirical techniques, dimensional analysis utilizes theoretical principles of fluid mechanics that provides valuable insights into parameter relationships. Based on data obtained from a steady flow mock loop under a wide range of pump operating points and fluid viscosities, flow and differential pressure estimate models were thus obtained using dimensional analysis. The algorithm was then validated using data from two other VentrAssist IRBPs. Linear correlations between estimated and measured pump flow over a flow range of 0.5 to 8.0 L/min resulted in a slope of 0.98 ([R.sup.2] = 0.9848). The average flow error was 0.20 [+ or -] 0.14 L/min (mean [+ or -] standard deviation) and the average percentage error was 5.79%. Similarly, linear correlations between estimated and measured pump differential pressure resulted in a slope of 1.027 ([R.sup.2] = 0.997) over a pressure range of 60 to 180 mmHg. The average differential pressure error was 1.84 [+ or -] 1.54 mmHg and the average percentage error was 1.51%. Index Terms--Dimensional analysis, flow estimation, implantable rotary blood pump (IRBP), left ventricular assist device (LVAD).

Published
2008

154. Wearable sensing and telehealth technology with potential applications in the coronavirus pandemic

Author

Ding, Xiao-Rong, Clifton, David, Ji, Nan, Lovell, Nigel H., Bonato, Paolo, Chen, Wei, Yu, Xinge, Xue, Zhong, Xiang, Ting, Long, Xi, Xu, Ke, Jiang, Xinyu, Wang, Qi, Yin, B., Feng, Guodong, Zhang, Yuan-Ting, Ding, Xiao-Rong, Clifton, David, Ji, Nan, Lovell, Nigel H., Bonato, Paolo, Chen, Wei, Yu, Xinge, Xue, Zhong, Xiang, Ting, Long, Xi, Xu, Ke, Jiang, Xinyu, Wang, Qi, Yin, B., Feng, Guodong, and Zhang, Yuan-Ting

Abstract

Coronavirus disease 2019 (COVID-19) has emerged as a pandemic with serious clinical manifestations including death. A pandemic at the large-scale like COVID-19 places extraordinary demands on the world's health systems, dramatically devastates vulnerable populations, and critically threatens the global communities in an unprecedented way. While tremendous efforts at the frontline are placed on detecting the virus, providing treatments and developing vaccines, it is also critically important to examine the technologies and systems for tackling disease emergence, arresting its spread and especially the strategy for diseases prevention. The objective of this article is to review enabling technologies and systems with various application scenarios for handling the COVID-19 crisis. The article will focus specifically on 1) wearable devices suitable for monitoring the populations at risk and those in quarantine, both for evaluating the health status of caregivers and management personnel, and for facilitating triage processes for admission to hospitals; 2) unobtrusive sensing systems for detecting the disease and for monitoring patients with relatively mild symptoms whose clinical situation could suddenly worsen in improvised hospitals; and 3) telehealth technologies for the remote monitoring and diagnosis of COVID-19 and related diseases. Finally, further challenges and opportunities for future directions of development are highlighted.

Published
2021

156. A comparison of 1-D models of cardiac pacemaker heterogeneity

Author

Cloherty, Shaun L., Dokos, Socrates, and Lovell, Nigel H.

Subjects
Pacemaker, Artificial (Heart) -- Mechanical properties, Pacemaker, Artificial (Heart) -- Models, Pacemaker, Artificial (Heart) -- Analysis, Action potentials (Electrophysiology) -- Analysis, Biological sciences, Business, Computers, Health care industry
Abstract

In this paper, we investigate the role of sinoatrial node (SAN) cellular heterogeneity in two key aspects of normal cardiac pacemaker function: frequency entrainment of the SAN, and propagation of excitation into the atrial tissue. Using detailed ionic models of electrical activity in SAN and atrial myocytes, we have formulated a number of one-dimensional models of SAN heterogeneity based on discrete-region (in which central and peripheral SAN type cell are separated into discrete regions), gradient and mosaic models of SAN organization. Each of the different models were assessed on their ability to achieve frequency entrainment of the SAN and activation of the adjoining atrial tissue in the presence of both uniform and linearly increasing conductivity profiles. Simulation results suggest that the gradient model of SAN heterogeneity, in which cells display a smooth variation in membrane properties from the center to the periphery of the SAN, produces action potential waveshapes and a site of earliest activation consistent with experimental observations in the intact SAN. The gradient model also achieves frequency entrainment of the SAN more easily than other models of SAN heterogeneity. Based on these results, we conclude that the gradient model of SAN heterogeneity, in the presence of a uniform conductivity profile, is the most likely model of SAN organization. Index Terms--Action potential heterogeneity, frequency entrainment, mathematical modeling, monodomain model, sinoatrial node.

Published
2006

159. Recommendation to Use Wearable-Based mHealth in Closed-Loop Management of Acute Cardiovascular Disease Patients During the COVID-19 Pandemic

Author

Ji, Nan, primary, Xiang, Ting, additional, Bonato, Paolo, additional, Lovell, Nigel H., additional, Ooi, Sze-Yuan, additional, Clifton, David A., additional, Akay, Metin, additional, Ding, Xiao-Rong, additional, Yan, Bryan P., additional, Mok, Vincent, additional, Fotiadis, Dimitrios I., additional, and Zhang, Yuan-Ting, additional

Published
2021
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172. Wearable Sensing and Telehealth Technology with Potential Applications in the Coronavirus Pandemic

Author

Ding, Xiaorong, primary, Clifton, David, additional, Ji, Nan, additional, Lovell, Nigel H., additional, Bonato, Paolo, additional, Chen, Wei, additional, Yu, Xinge, additional, Xue, Zhong, additional, Xiang, Ting, additional, Long, Xi, additional, Xu, Ke, additional, Jiang, Xinyu, additional, Wang, Qi, additional, Yin, Bin, additional, Feng, Guodong, additional, and Zhang, Yuan-Ting, additional

Published
2021
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175. Assessment of Hypertension Using Clinical Electrocardiogram Features: A First-Ever Review

Author

Bird, Kathleen, primary, Chan, Gabriel, additional, Lu, Huiqi, additional, Greeff, Heloise, additional, Allen, John, additional, Abbott, Derek, additional, Menon, Carlo, additional, Lovell, Nigel H., additional, Howard, Newton, additional, Chan, Wee-Shian, additional, Fletcher, Richard Ribon, additional, Alian, Aymen, additional, Ward, Rabab, additional, and Elgendi, Mohamed, additional

Published
2020
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187. Multimodal Photoplethysmography-Based Approaches for Improved Detection of Hypertension

Author

Welykholowa, Kaylie, primary, Hosanee, Manish, additional, Chan, Gabriel, additional, Cooper, Rachel, additional, Kyriacou, Panayiotis A., additional, Zheng, Dingchang, additional, Allen, John, additional, Abbott, Derek, additional, Menon, Carlo, additional, Lovell, Nigel H., additional, Howard, Newton, additional, Chan, Wee-Shian, additional, Lim, Kenneth, additional, Fletcher, Richard, additional, Ward, Rabab, additional, and Elgendi, Mohamed, additional

Published
2020
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189. Cuffless Single-Site Photoplethysmography for Blood Pressure Monitoring

Author

Hosanee, Manish, primary, Chan, Gabriel, additional, Welykholowa, Kaylie, additional, Cooper, Rachel, additional, Kyriacou, Panayiotis A., additional, Zheng, Dingchang, additional, Allen, John, additional, Abbott, Derek, additional, Menon, Carlo, additional, Lovell, Nigel H., additional, Howard, Newton, additional, Chan, Wee-Shian, additional, Lim, Kenneth, additional, Fletcher, Richard, additional, Ward, Rabab, additional, and Elgendi, Mohamed, additional

Published
2020
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191. First biopotential recordings from a liquid crystal optrode

Author

Silvestri, Leonardo, primary, Al Abed, Amr, additional, Revol, Emilie C. M., additional, Firth, Josiah, additional, Wei, Yuan, additional, Wang, Han, additional, Gouailhardou, Nathalie, additional, Lehmann, Torsten, additional, Lovell, Nigel H., additional, and Ladouceur, Francois, additional

Published
2020
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