The Experts below are selected from a list of 168 Experts worldwide ranked by ideXlab platform
Anastasios Petrou - One of the best experts on this subject based on the ideXlab platform.
-
Cardiac Output Estimation: Online Implementation for Left Ventricular Assist Device Support.
IEEE transactions on bio-medical engineering, 2020Co-Authors: Anastasios Petrou, Mirko Meboldt, Menelaos Kanakis, Konstantinos Magkoutas, Bob De Vries, Marianne SchmiddanersAbstract:Objective We present a novel pipeline that consists of various algorithms for the estimation of the cardiac output (CO) during ventricular assist devices (VADs) support using a single Pump Inlet Pressure (PIP) sensor as well as Pump intrinsic signals. Methods A machine learning (ML) model was constructed for the prediction of the aortic valve opening status. When a closed aortic valve is detected, the estimated CO equals the estimated Pump flow. Otherwise, the estimated CO equals the sum of the estimated Pump flow and the aortic valve flow, estimated via a Kalman-filter approach. Both the pathophysiological conditions and the Pump speed of an in-vitro test bench were adjusted in various combinations to evaluate the performance of the pipeline, as well as the individual estimators. Results The ML model yielded a Matthews correlation coefficient of 0.771, a sensitivity of 0.913 and a specificity of 0.871. An overall CO root mean square error (RMSE) of 0.69 L/min was achieved. Replacing the Pump flow and aortic Pressure estimators with sensors would decrease the RMSE below 0.5 L/min. Conclusion The performance of the proposed pipeline is considered the state of the art for VADs with an integrated PIP sensor. The effect of the individual estimators on the overall performance of the pipeline was thoroughly investigated and their limitations were identified for future research. Significance The clinical application of the proposed solution could provide the clinicians with essential information about the interaction between the patient's heart and the VAD to further improve the VAD therapy.
-
comparison of flow estimators for rotary blood Pumps an in vitro and in vivo study
Annals of Biomedical Engineering, 2018Co-Authors: Anastasios Petrou, Mirko Meboldt, Daniel Kuster, Marianne Schmid DanersAbstract:Various approaches for estimating the flow rate of a rotary blood Pump have been proposed for monitoring and control purposes. They have been evaluated under different test conditions and, therefore, a direct comparison among them is difficult. Furthermore, a limited performance has been reported for the areas where the Pump flow and motor current present a non-monotonic relationship. In this regard, we selected most approaches that have been presented in literature and added a modified one, resulting in four estimators, which are either non-invasive or invasive, i.e., Inlet and outlet Pump Pressure sensors are used. Data from in vitro and in vivo studies with the Deltastream Pump DP2 were used to compare the estimators under the same test conditions. These data included both constant and varying pre- and afterload, contractility, viscosity, as well as Pump speed settings. Bland–Altman plots were used to evaluate the performance of the estimators. The mean error of the overall estimated flow in vitro ranged from 0.002 to 0.38 L/min and the limits of agreement (LoA) between ± 2 L/min. During negative flows the mean error decreased by about 25% when the Pump Inlet Pressure was added as an input. In vivo, the mean errors increased, while the LoA remained in the same range. An estimator based on Pump Pressure difference improves the reliability in areas where flow and current relationship is not monotonic. A trade-off between estimation accuracy and number of sensors was identified. The estimation objective and the potential errors should be considered when selecting an estimation approach and designing the Pump systems.
-
A Novel Multi-objective Physiological Control System for Rotary Left Ventricular Assist Devices
Annals of Biomedical Engineering, 2017Co-Authors: Anastasios Petrou, Marcial Monn, Mirko Meboldt, Marianne Schmid DanersAbstract:—Various control and monitoring algorithms have been proposed to improve the left-ventricular assist device (LVAD) therapy by reducing the still-occurring adverse events. We developed a novel multi-objective physiological control system that relies on the Pump Inlet Pressure (PIP). Signal-processing algorithms have been implemented to extract the required features from the PIP. These features then serve for meeting various objectives: Pump flow adaptation to the perfusion requirements, aortic valve opening for a predefined time, augmentation of the aortic pulse Pressure, and monitoring of the LV pre-and afterload conditions as well as the cardiac rhythm. Controllers were also implemented to ensure a safe operation and prevent LV suction, overload, and Pump backflow. The performance of the control system was evaluated in vitro, under preload, afterload and contractility variations. The Pump flow adapted in a physiological manner, following the preload changes, while the aortic pulse Pressure yielded a threefold increase compared to a constant-speed operation. The status of the aortic valve was detected with an overall accuracy of 86% and was controlled as desired. The proposed system showed its potential for a safe physiological response to varying perfusion requirements that reduces the risk of myocardial atrophy and offers important hemodynamic indices for patient monitoring during LVAD therapy.
-
A Physiological Controller for Turbodynamic Ventricular Assist Devices Based on Left Ventricular Systolic Pressure.
Artificial organs, 2016Co-Authors: Anastasios Petrou, Mirko Meboldt, Gregor Ochsner, Raffael Amacher, Panagiotis Pergantis, Mathias Rebholz, Marianne Schmid DanersAbstract:The current article presents a novel physiological feedback controller for turbodynamic ventricular assist devices (tVADs). This controller is based on the recording of the left ventricular (LV) Pressure measured at the Inlet cannula of a tVAD thus requiring only one Pressure sensor. The LV systolic Pressure (SP) is proposed as an indicator to determine the varying perfusion requirements. The algorithm to extract the SP from the Pump Inlet Pressure signal used for the controller to adjust the speed of the tVAD shows robust behavior. Its performance was evaluated on a hybrid mock circulation. The experiments with changing perfusion requirements were compared with a physiological circulation and a pathological one assisted with a tVAD operated at constant speed. A sensitivity analysis of the controller parameters was conducted to identify their limits and their influence on a circulation. The performance of the proposed SP controller was evaluated for various values of LV contractility, as well as for a simulated Pressure sensor drift. The response of a pathological circulation assisted by a tVAD controlled by the introduced SP controller matched the physiological circulation well, while over- and underPumping events were eliminated. The controller presented a robust performance during experiments with simulated Pressure sensor drift.
Marianne Schmid Daners - One of the best experts on this subject based on the ideXlab platform.
-
comparison of flow estimators for rotary blood Pumps an in vitro and in vivo study
Annals of Biomedical Engineering, 2018Co-Authors: Anastasios Petrou, Mirko Meboldt, Daniel Kuster, Marianne Schmid DanersAbstract:Various approaches for estimating the flow rate of a rotary blood Pump have been proposed for monitoring and control purposes. They have been evaluated under different test conditions and, therefore, a direct comparison among them is difficult. Furthermore, a limited performance has been reported for the areas where the Pump flow and motor current present a non-monotonic relationship. In this regard, we selected most approaches that have been presented in literature and added a modified one, resulting in four estimators, which are either non-invasive or invasive, i.e., Inlet and outlet Pump Pressure sensors are used. Data from in vitro and in vivo studies with the Deltastream Pump DP2 were used to compare the estimators under the same test conditions. These data included both constant and varying pre- and afterload, contractility, viscosity, as well as Pump speed settings. Bland–Altman plots were used to evaluate the performance of the estimators. The mean error of the overall estimated flow in vitro ranged from 0.002 to 0.38 L/min and the limits of agreement (LoA) between ± 2 L/min. During negative flows the mean error decreased by about 25% when the Pump Inlet Pressure was added as an input. In vivo, the mean errors increased, while the LoA remained in the same range. An estimator based on Pump Pressure difference improves the reliability in areas where flow and current relationship is not monotonic. A trade-off between estimation accuracy and number of sensors was identified. The estimation objective and the potential errors should be considered when selecting an estimation approach and designing the Pump systems.
-
A Physiological Controller for Turbodynamic Ventricular Assist Devices Based on Left Ventricular Systolic Pressure.
Artificial organs, 2016Co-Authors: Anastasios Petrou, Mirko Meboldt, Gregor Ochsner, Raffael Amacher, Panagiotis Pergantis, Mathias Rebholz, Marianne Schmid DanersAbstract:The current article presents a novel physiological feedback controller for turbodynamic ventricular assist devices (tVADs). This controller is based on the recording of the left ventricular (LV) Pressure measured at the Inlet cannula of a tVAD thus requiring only one Pressure sensor. The LV systolic Pressure (SP) is proposed as an indicator to determine the varying perfusion requirements. The algorithm to extract the SP from the Pump Inlet Pressure signal used for the controller to adjust the speed of the tVAD shows robust behavior. Its performance was evaluated on a hybrid mock circulation. The experiments with changing perfusion requirements were compared with a physiological circulation and a pathological one assisted with a tVAD operated at constant speed. A sensitivity analysis of the controller parameters was conducted to identify their limits and their influence on a circulation. The performance of the proposed SP controller was evaluated for various values of LV contractility, as well as for a simulated Pressure sensor drift. The response of a pathological circulation assisted by a tVAD controlled by the introduced SP controller matched the physiological circulation well, while over- and underPumping events were eliminated. The controller presented a robust performance during experiments with simulated Pressure sensor drift.
Mirko Meboldt - One of the best experts on this subject based on the ideXlab platform.
-
Cardiac Output Estimation: Online Implementation for Left Ventricular Assist Device Support.
IEEE transactions on bio-medical engineering, 2020Co-Authors: Anastasios Petrou, Mirko Meboldt, Menelaos Kanakis, Konstantinos Magkoutas, Bob De Vries, Marianne SchmiddanersAbstract:Objective We present a novel pipeline that consists of various algorithms for the estimation of the cardiac output (CO) during ventricular assist devices (VADs) support using a single Pump Inlet Pressure (PIP) sensor as well as Pump intrinsic signals. Methods A machine learning (ML) model was constructed for the prediction of the aortic valve opening status. When a closed aortic valve is detected, the estimated CO equals the estimated Pump flow. Otherwise, the estimated CO equals the sum of the estimated Pump flow and the aortic valve flow, estimated via a Kalman-filter approach. Both the pathophysiological conditions and the Pump speed of an in-vitro test bench were adjusted in various combinations to evaluate the performance of the pipeline, as well as the individual estimators. Results The ML model yielded a Matthews correlation coefficient of 0.771, a sensitivity of 0.913 and a specificity of 0.871. An overall CO root mean square error (RMSE) of 0.69 L/min was achieved. Replacing the Pump flow and aortic Pressure estimators with sensors would decrease the RMSE below 0.5 L/min. Conclusion The performance of the proposed pipeline is considered the state of the art for VADs with an integrated PIP sensor. The effect of the individual estimators on the overall performance of the pipeline was thoroughly investigated and their limitations were identified for future research. Significance The clinical application of the proposed solution could provide the clinicians with essential information about the interaction between the patient's heart and the VAD to further improve the VAD therapy.
-
comparison of flow estimators for rotary blood Pumps an in vitro and in vivo study
Annals of Biomedical Engineering, 2018Co-Authors: Anastasios Petrou, Mirko Meboldt, Daniel Kuster, Marianne Schmid DanersAbstract:Various approaches for estimating the flow rate of a rotary blood Pump have been proposed for monitoring and control purposes. They have been evaluated under different test conditions and, therefore, a direct comparison among them is difficult. Furthermore, a limited performance has been reported for the areas where the Pump flow and motor current present a non-monotonic relationship. In this regard, we selected most approaches that have been presented in literature and added a modified one, resulting in four estimators, which are either non-invasive or invasive, i.e., Inlet and outlet Pump Pressure sensors are used. Data from in vitro and in vivo studies with the Deltastream Pump DP2 were used to compare the estimators under the same test conditions. These data included both constant and varying pre- and afterload, contractility, viscosity, as well as Pump speed settings. Bland–Altman plots were used to evaluate the performance of the estimators. The mean error of the overall estimated flow in vitro ranged from 0.002 to 0.38 L/min and the limits of agreement (LoA) between ± 2 L/min. During negative flows the mean error decreased by about 25% when the Pump Inlet Pressure was added as an input. In vivo, the mean errors increased, while the LoA remained in the same range. An estimator based on Pump Pressure difference improves the reliability in areas where flow and current relationship is not monotonic. A trade-off between estimation accuracy and number of sensors was identified. The estimation objective and the potential errors should be considered when selecting an estimation approach and designing the Pump systems.
-
A Novel Multi-objective Physiological Control System for Rotary Left Ventricular Assist Devices
Annals of Biomedical Engineering, 2017Co-Authors: Anastasios Petrou, Marcial Monn, Mirko Meboldt, Marianne Schmid DanersAbstract:—Various control and monitoring algorithms have been proposed to improve the left-ventricular assist device (LVAD) therapy by reducing the still-occurring adverse events. We developed a novel multi-objective physiological control system that relies on the Pump Inlet Pressure (PIP). Signal-processing algorithms have been implemented to extract the required features from the PIP. These features then serve for meeting various objectives: Pump flow adaptation to the perfusion requirements, aortic valve opening for a predefined time, augmentation of the aortic pulse Pressure, and monitoring of the LV pre-and afterload conditions as well as the cardiac rhythm. Controllers were also implemented to ensure a safe operation and prevent LV suction, overload, and Pump backflow. The performance of the control system was evaluated in vitro, under preload, afterload and contractility variations. The Pump flow adapted in a physiological manner, following the preload changes, while the aortic pulse Pressure yielded a threefold increase compared to a constant-speed operation. The status of the aortic valve was detected with an overall accuracy of 86% and was controlled as desired. The proposed system showed its potential for a safe physiological response to varying perfusion requirements that reduces the risk of myocardial atrophy and offers important hemodynamic indices for patient monitoring during LVAD therapy.
-
A Physiological Controller for Turbodynamic Ventricular Assist Devices Based on Left Ventricular Systolic Pressure.
Artificial organs, 2016Co-Authors: Anastasios Petrou, Mirko Meboldt, Gregor Ochsner, Raffael Amacher, Panagiotis Pergantis, Mathias Rebholz, Marianne Schmid DanersAbstract:The current article presents a novel physiological feedback controller for turbodynamic ventricular assist devices (tVADs). This controller is based on the recording of the left ventricular (LV) Pressure measured at the Inlet cannula of a tVAD thus requiring only one Pressure sensor. The LV systolic Pressure (SP) is proposed as an indicator to determine the varying perfusion requirements. The algorithm to extract the SP from the Pump Inlet Pressure signal used for the controller to adjust the speed of the tVAD shows robust behavior. Its performance was evaluated on a hybrid mock circulation. The experiments with changing perfusion requirements were compared with a physiological circulation and a pathological one assisted with a tVAD operated at constant speed. A sensitivity analysis of the controller parameters was conducted to identify their limits and their influence on a circulation. The performance of the proposed SP controller was evaluated for various values of LV contractility, as well as for a simulated Pressure sensor drift. The response of a pathological circulation assisted by a tVAD controlled by the introduced SP controller matched the physiological circulation well, while over- and underPumping events were eliminated. The controller presented a robust performance during experiments with simulated Pressure sensor drift.
Marianne Schmid Daners - One of the best experts on this subject based on the ideXlab platform.
-
A Novel Multi-objective Physiological Control System for Rotary Left Ventricular Assist Devices
Annals of Biomedical Engineering, 2017Co-Authors: Anastasios Petrou, Marcial Monn, Mirko Meboldt, Marianne Schmid DanersAbstract:—Various control and monitoring algorithms have been proposed to improve the left-ventricular assist device (LVAD) therapy by reducing the still-occurring adverse events. We developed a novel multi-objective physiological control system that relies on the Pump Inlet Pressure (PIP). Signal-processing algorithms have been implemented to extract the required features from the PIP. These features then serve for meeting various objectives: Pump flow adaptation to the perfusion requirements, aortic valve opening for a predefined time, augmentation of the aortic pulse Pressure, and monitoring of the LV pre-and afterload conditions as well as the cardiac rhythm. Controllers were also implemented to ensure a safe operation and prevent LV suction, overload, and Pump backflow. The performance of the control system was evaluated in vitro, under preload, afterload and contractility variations. The Pump flow adapted in a physiological manner, following the preload changes, while the aortic pulse Pressure yielded a threefold increase compared to a constant-speed operation. The status of the aortic valve was detected with an overall accuracy of 86% and was controlled as desired. The proposed system showed its potential for a safe physiological response to varying perfusion requirements that reduces the risk of myocardial atrophy and offers important hemodynamic indices for patient monitoring during LVAD therapy.
Nigel H. Lovell - One of the best experts on this subject based on the ideXlab platform.
-
Non-invasive estimation and control of Inlet Pressure in an implantable rotary blood Pump for heart failure patients
Physiological measurement, 2011Co-Authors: Abdul-hakeem H. Alomari, Andrey V. Savkin, Peter J. Ayre, Einly Lim, David Glen Mason, Robert F. Salamonsen, John F. Fraser, Nigel H. LovellAbstract:We propose a dynamical model for mean Inlet Pressure estimation in an implantable rotary blood Pump during the diastolic period. Non-invasive measurements of Pump impeller rotational speed (ω), motor power (P), and pulse width modulation signal acquired from the Pump controller were used as inputs to the model. The model was validated over a wide range of speed ramp studies, including (i) healthy (C1), variations in (ii) heart contractility (C2); (iii) afterload (C2, C3, C4), and (iv) preload (C5, C6, C7). Linear regression analysis between estimated and extracted mean Inlet Pressure obtained from in vivo animal data (greyhound dogs, N = 3) resulted in a highly significant correlation coefficients (R 2 = 0.957, 0.961, 0.958, 0.963, 0.940, 0.946, and 0.959) and mean absolute errors of (e = 1.604, 2.688, 3.667, 3.990, 2.791, 3.215, and 3.225 mmHg) during C1, C2, C3, C4, C5, C6, and C7, respectively. The proposed model was also used to design a controller to regulate mean diastolic Pump Inlet Pressure using non-invasively measured ω and P .I n the presence of model uncertainty, the controller was able to track and settle to the desired input within a finite number of sampling periods and minimal error (0.92 mmHg). The model developed herein will play a crucial role in
-
Sensorless estimation of Inlet Pressure in implantable rotary blood Pump for heart failure patients
Electronics Letters, 2010Co-Authors: Abdul-hakeem H. Alomari, Andrey V. Savkin, Peter J. Ayre, Einly Lim, Nigel H. LovellAbstract:A dynamical model for mean Inlet Pressure estimation in an implantable rotary blood Pump is proposed. Noninvasive measurements of Pump motor power ( P ), pulse width modulation, and impeller rotational speed (?) were used as inputs to the model. Linear regression analysis between estimated and measured Inlet Pressures obtained from in vivo greyhound data ( N = 3) resulted in a highly significant correlation ( R 2 = 0.957) and a mean absolute error ( e ) of 2.292 mmHg. Furthermore, the proposed model was stable which allowed accurate study and estimation of the transient response and the dynamics of the Pump Inlet Pressure ( P in ).
-
Modeling and control of an implantable rotary blood Pump for heart failure patients
Proceedings of the 2010 American Control Conference, 2010Co-Authors: Abdul-hakeem H. Alomari, Andrey V. Savkin, Peter J. Ayre, Einly Lim, Nigel H. LovellAbstract:We propose a dynamical model for mean Inlet Pressure estimation in an implantable rotary blood Pump (IRBP). Noninvasive measurements of Pump impeller rotational speed, motor power, and pulse width modulation signal (PWM) to the motor controller were used as inputs to the model. Linear regression between estimated and measured Inlet Pressure resulted in a highly significant correlation (R2 = 0.9503) and small mean absolute error (e = 2.31 mmHg). The proposed model was also used to design a controller to regulate Pump Inlet Pressure using noninvasively measured Pump rotational speed and motor power. The control algorithm was tested using both constant and square wave reference inputs. In the presence of models uncertainties, the controller was able to track and settle to the desired input within a finite number of sampling periods with minimal error.
