The Experts below are selected from a list of 9327 Experts worldwide ranked by ideXlab platform
Finn Gustafsson - One of the best experts on this subject based on the ideXlab platform.
-
Pump Speed modulations and sub maximal exercise tolerance in left ventricular assist device recipients a double blind randomized trial
Journal of Heart and Lung Transplantation, 2017Co-Authors: Mette Holme Jung, Stuart D Russell, Brian A Houston, Finn GustafssonAbstract:Background The effect of Pump Speed increase on sub-maximal exercise tolerance, corresponding to activities of daily living (ADLs), is unknown. The aim of this study was to determine the effects of increasing Pump Speed during exercise at a sub-maximal level below anaerobic threshold (AT). Methods Patients each completed 3 exercise sessions on an ergometer cycle. On Day 1 workload at AT was defined. On Day 2 of the study, 2 sub-maximal tests at a workload below AT were undertaken: one at fixed baseline Pump Speed (Speed base ) and the other with baseline Pump Speed + 800 rpm (Speed inc ). The sequence of the 2 sub-maximal tests was determined by randomization. Both patient and physician were blinded to the sequence. Exercise duration, oxygen consumption (VO2) and rate of perceived exertion (RPE), using the Borg scale (score 6 to 20), were recorded. Results Nineteen patients (all with a HeartMate II ventricular assist device) completed 57 exercise tests. Baseline Pump Speed was 9,326 ± 378 rpm. At AT, workload was 63 ± 26 W (25 to 115 W) and VO 2 was 79 ± 14% of maximum. Exercise duration improved by 106 ± 217 seconds (~13%) in Speed inc compared with Speed base (837 ± 358 vs 942 ± 359 seconds; p = 0.048). The RPE was 13.2 ± 2.5 in Speed base vs 12.7 ± 2.4 in Speed inc ( p = 0.2). Conclusion Increasing Pump Speed by 800 rpm during sustained, low-intensity physical activity is safe and prolongs exercise duration in patients supported with a HeartMate II device. Automated Pump Speed increase during light exercise may contribute to improved quality of life by facilitating ADLs.
-
effect of increasing Pump Speed during exercise on peak oxygen uptake in heart failure patients supported with a continuous flow left ventricular assist device a double blind randomized study
European Journal of Heart Failure, 2014Co-Authors: Mette Holme Jung, Kasper Rossing, Kaare Sander, Soeren Boesgaard, Stuart D Russell, Peter Skov Olsen, P B Hansen, Finn GustafssonAbstract:Aims Continuous-flow left ventricular assist device (CF-LVAD) implantation is associated with improved quality of life, but the effect on exercise capacity is less well documented. It is uncertain whether a fixed CF-LVAD Pump Speed, which allows for sufficient circulatory support at rest, remains adequate during exercise. The aim of this study was to evaluate the effects of fixed versus incremental Pump Speed on peak oxygen uptake (peak VO2) during a maximal exercise test. Methods and results In CF-LVAD (HeartMate II) patients exercise testing measuring peak oxygen uptake (VO2) was performed on an ergometer bike twice in one day: once with fixed Pump Speed (testfix) and once with incremental Pump Speed (testinc). The order of testfix and testinc in each patient was determined by randomization. During testinc Pump Speed was increased from the baseline value by 400 rpm/2 min. Fourteen patients (aged 23–69 years) were included with a mean support duration of 465 ± 483 days. Baseline CF-LVAD Speed was 9357 ± 238 rpm and during testinc Speed was increased by a mean of 1486 ± 775 rpm. Mean peak VO2 was significantly higher in testinc compared with testfix (15.4 ± 5.9 mL/kg/min vs. 14.1 ± 6.3 mL/kg/min; P = 0.012), corresponding to a 9.2% increase. All exercise tests (n = 28) were adequately performed with RER > 1. Conclusion Increasing Pump Speed during exercise augments peak VO2 in patients supported with CF-LVADs. An automatic Speed-change function in future generations of CF-LVADs might improve functional capacity.
-
Effect of increasing Pump Speed during exercise on peak oxygen uptake in heart failure patients supported with a continuous-flow left ventricular assist device. A double-blind randomized study
European Journal of Heart Failure, 2014Co-Authors: Mette Holme Jung, Kasper Rossing, Peter Bo Hansen, Kaare Sander, Soeren Boesgaard, Stuart D Russell, Peter Skov Olsen, Finn GustafssonAbstract:AIMS: Continuous-flow left ventricular assist device (CF-LVAD) implantation is associated with improved quality of life, but the effect on exercise capacity is less well documented. It is uncertain whether a fixed CF-LVAD Pump Speed, which allows for sufficient circulatory support at rest, remains adequate during exercise. The aim of this study was to evaluate the effects of fixed versus incremental Pump Speed on peak oxygen uptake (peak VO2 ) during a maximal exercise test.\n\nMETHODS AND RESULTS: In CF-LVAD (HeartMate II) patients exercise testing measuring peak oxygen uptake (VO2 ) was performed on an ergometer bike twice in one day: once with fixed Pump Speed (test(fix) ) and once with incremental Pump Speed (test(inc) ). The order of test(fix) and test(inc) in each patient was determined by randomization. During test(inc) Pump Speed was increased from the baseline value by 400 rpm/2 min. Fourteen patients (aged 23-69 years) were included with a mean support duration of 465 ± 483 days. Baseline CF-LVAD Speed was 9357 ± 238 rpm and during test(inc) Speed was increased by a mean of 1486 ± 775 rpm. Mean peak VO2 was significantly higher in test(inc) compared with test(fix) (15.4 ± 5.9 mL/kg/min vs. 14.1 ± 6.3 mL/kg/min; P = 0.012), corresponding to a 9.2% increase. All exercise tests (n = 28) were adequately performed with RER > 1.\n\nCONCLUSION: Increasing Pump Speed during exercise augments peak VO2 in patients supported with CF-LVADs. An automatic Speed-change function in future generations of CF-LVADs might improve functional capacity.
-
Increasing Pump Speed During Exercise Improves Peak Oxygen Consumption in Heart Failure Patients Supported With Continuous-Flow Left Ventricular Assist Devices - A Double-Blind Randomized Study
The Journal of Heart and Lung Transplantation, 2014Co-Authors: Mette Holme Jung, Kasper Rossing, Peter Bo Hansen, Kaare Sander, Soeren Boesgaard, Stuart D Russell, Peter Skov Olsen, Finn GustafssonAbstract:Purpose: Continuous-flow left ventricular assist device (CF-LVAD) implantation is associated with improved quality of life, yet exercise capacity is not normalized. It is uncertain whether a fixed CF-LVAD Pump Speed, which allows for sufficient circulatory support at rest, remains adequate during exercise. The aim of this study was to evaluate the effects of fixed versus incremental Pump Speed on peak oxygen consumption (VO2) during a maximal exercise test. Method: 14 CF-LVAD HeartMate II (HM II) outpatients (aged 23-69) were included in the study. Exercise testing was performed on an ergometer-bike twice in one dayonce with fixed Pump Speed (test-fix) and once with incremental Pump Speed (test-inc). The order of test-fix and test-inc in each patient was determined by randomization, and the patient and the physician directing the ergometry were blinded to the sequence. During test-inc Pump Speed was increased from the baseline value by 400 rpm/2 minutes. Peak VO2 was measured using "breath-by-breath" technique. Results: Out of 14 patients (12 M; 2 F) 10 were bridge-to-transplantation and 4 were destination therapy. Six patients had ischemic cardiomyopathy and 8 non-ischemic cardiomyopathy. Median support duration was 359 (range: 38 days to 5 years) days. NYHA class varied between I and IIIa with a median LVEF of 13 (range: 3-28) %. Baseline HM II median Speed was 9400 (range: 9000 to 9800) rpm. During test-inc Speed was increased by a mean of 1200 (range: 800-2800) rpm. No adverse events (eg suction, arrhythmia) were recorded during the study. Mean peak VO2 was higher during test-inc compared to test-fix (15.4 +/-1.6 ml/min/kg versus 14.1+/-1.7 ml/min/kg; p 1. Mean exercise time did not differ between test-inc (7 min 54 sec; range: 264 to 921 sec) and test-fix (7 min 50 sec; range: 233 to 938 sec); p=0.71. Median work load capacity between groups did not differ either, test-inc (100 W; range: 75-200) versus test-fix (100 W; range:50-200); p=0.44. Post-exercise blood lactate was not different after test-fix and test-inc. Conclusion: Increasing Pump Speed during exercise augments peak oxygen consumption in patients supported with CF-LVAD. Capability to perform activities of daily life is closely related to VO2, this making enhancement of peak oxygen consumption during exercise a desirable aim. An automatic Speed-change function in future generation CF-LVADs might improve functional capacity.
-
Central and Peripheral Blood Flow During Exercise With a Continuous-Flow Left Ventricular Assist Device Constant Versus Increasing Pump Speed: A Pilot Study
Circulation-heart Failure, 2011Co-Authors: Patrice Brassard, Soeren Boesgaard, Finn Gustafsson, Peter Skov Olsen, Annette S Jensen, Nikolai Baastrup Nordsborg, Jacob E Moller, Christian Hassager, Hansen Pb, K SanderAbstract:Background —End-stage heart failure is associated with impaired cardiac output (CO) and organ blood flow. We determined whether CO and peripheral perfusion are maintained during exercise in patients with an axial-flow left ventricular assist device (LVAD) and whether an increase in LVAD Pump Speed with work rate would increase organ blood flow. Methods and Results —Invasively determined CO and leg blood flow and Doppler-determined cerebral perfusion were measured during two incremental cycle exercise tests on the same day in eight patients provided with a HeartMate II ® LVAD. In random order, patients exercised both with a constant (~9775 rpm) and with an increasing Pump Speed (+400 rpm per exercise stage). At 60 Watts, the elevation in CO was more pronounced with increased Pump Speed (8.7±0.6 vs. 8.1±1.1 L min -1 ; mean±SD; P=0.05), but at maximal exercise, increases in CO (from 7.0±0.9 to 13.6±2.5 L min -1 ; P -1 per leg; median (range); P -1 during exercise, but in LVAD patients with a constant Pump Speed it was low at rest (39±14 cm sec -1 ) and remained unchanged during exercise, whereas in patients with increasing Pump Speed, it increased by 5.2±2.8 cm sec -1 at 60 Watts (P
Nicholas R. Banner - One of the best experts on this subject based on the ideXlab platform.
-
investigation of the characteristics of heartware hvad and thoratec heartmate ii under steady and pulsatile flow conditions
Artificial Organs, 2016Co-Authors: Mumin R. Noor, Christopher T. Bowles, Nicholas R. Banner, Chong H Ho, Kim H Parker, Andre R SimonAbstract:The aim of this study was to elucidate the dynamic characteristics of the Thoratec HeartMate II (HMII) and the HeartWare HVAD (HVAD) left ventricular assist devices (LVADs) under clinically representative in vitro operating conditions. The performance of the two LVADs were compared in a normothermic, human blood-filled mock circulation model under conditions of steady (nonpulsatile) flow and under simulated physiologic conditions. These experiments were repeated using 5% dextrose in order to determine its suitability as a blood analog. Under steady flow conditions, for the HMII, approximately linear inverse LVAD differential pressure (H) versus flow (Q) relationships were observed with good correspondence between the results of blood and 5% dextrose under all conditions except at a Pump Speed of 9000 rpm. For the HVAD, the corresponding relationships were inverse curvilinear and with good correspondence between the blood-derived and 5% dextrose-derived relationships in the flow rate range of 2-6 L/min and at Pump Speeds up to 3000 rpm. Under pulsatile operating conditions, for each LVAD operating at a particular Pump Speed, an counterclockwise loop was inscribed in the HQ domain during a simulated cardiac cycle (HQ loop); this showed that there was a variable phase relationship between LVAD differential pressure and LVAD flow. For both the HMII and HVAD, increasing Pump Speed was associated with a right-hand and upward shift of the HQ loop and simulation of impairment of left ventricular function was associated with a decrease in loop area. During clinical use, not only does the pressure differential across the LVAD and its flow rate vary continuously, but their phase relationship is variable. This behavior is inadequately described by the widely accepted representation of a plot of pressure differential versus flow derived under steady conditions. We conclude that the dynamic HQ loop is a more meaningful representation of clinical operating conditions than the widely accepted steady flow HQ curve.
-
relationship between Pump Speed and exercise capacity during heartmate ii left ventricular assist device support influence of residual left ventricular function
European Journal of Heart Failure, 2012Co-Authors: Mumin R. Noor, Christopher T. Bowles, Nicholas R. BannerAbstract:Aims Patients treated with a Thoratec HeartMate II left ventricular assist device (LVAD) are supported at a fixed Pump Speed. It is uncertain whether Pump Speed has a significant effect on exercise capacity. We investigated the relationship between Pump Speed and exercise capacity and the influence of residual LV function Methods and results We exercised 30 patients 6 months after HeartMate II implantation at clinical Pump Speed (typically 9000 r.p.m.) and again at the lowest Speed available (6000 r.p.m.). Overall, peak oxygen uptake (pkVO2) positively correlated with LV ejection fraction (LVEF) both at the clinical Pump Speed (r = 0.41, P = 0.03) and after Pump Speed reduction (r = 0.50, P = 0.01). We divided the patients into two groups; those with higher LVEF (LVEF ≥40%) and those with lower LVEF (LVEF <40%) at the time of exercise testing. The response to Speed change was different between the two groups. In the higher LVEF group, the impact of LVAD Pump Speed reduction was minimal (pkVO2 21.4 ± 4.8 mL/kg/min vs. 20.8 ± 5.5 mL/kg/min, P = 0.38). In the lower LVEF group, the pkVO2 was lower at both Speeds; 17.2 ± 5.3 and 14.7 ± 5.9 mL/kg/min, respectively. In the lower LVEF group, the pkVO2 decreased by 2.5 mL/kg/min (P = 0.02) with Speed reduction. Conclusions HeartMate II patients with lower residual LV function had a lower pkVO2 and were more sensitive to Pump Speed reduction. This suggests that modulation of LVAD Speed during exercise could be of benefit to this group of patients.
-
Relationship between Pump Speed and exercise capacity during HeartMate II left ventricular assist device support: influence of residual left ventricular function
European Journal of Heart Failure, 2012Co-Authors: Mumin R. Noor, Christopher T. Bowles, Nicholas R. BannerAbstract:Aims Patients treated with a Thoratec HeartMate II left ventricular assist device (LVAD) are supported at a fixed Pump Speed. It is uncertain whether Pump Speed has a significant effect on exercise capacity. We investigated the relationship between Pump Speed and exercise capacity and the influence of residual LV function Methods and results We exercised 30 patients 6 months after HeartMate II implantation at clinical Pump Speed (typically 9000 r.p.m.) and again at the lowest Speed available (6000 r.p.m.). Overall, peak oxygen uptake (pkVO2) positively correlated with LV ejection fraction (LVEF) both at the clinical Pump Speed (r = 0.41, P = 0.03) and after Pump Speed reduction (r = 0.50, P = 0.01). We divided the patients into two groups; those with higher LVEF (LVEF ≥40%) and those with lower LVEF (LVEF
Christopher T. Bowles - One of the best experts on this subject based on the ideXlab platform.
-
investigation of the characteristics of heartware hvad and thoratec heartmate ii under steady and pulsatile flow conditions
Artificial Organs, 2016Co-Authors: Mumin R. Noor, Christopher T. Bowles, Nicholas R. Banner, Chong H Ho, Kim H Parker, Andre R SimonAbstract:The aim of this study was to elucidate the dynamic characteristics of the Thoratec HeartMate II (HMII) and the HeartWare HVAD (HVAD) left ventricular assist devices (LVADs) under clinically representative in vitro operating conditions. The performance of the two LVADs were compared in a normothermic, human blood-filled mock circulation model under conditions of steady (nonpulsatile) flow and under simulated physiologic conditions. These experiments were repeated using 5% dextrose in order to determine its suitability as a blood analog. Under steady flow conditions, for the HMII, approximately linear inverse LVAD differential pressure (H) versus flow (Q) relationships were observed with good correspondence between the results of blood and 5% dextrose under all conditions except at a Pump Speed of 9000 rpm. For the HVAD, the corresponding relationships were inverse curvilinear and with good correspondence between the blood-derived and 5% dextrose-derived relationships in the flow rate range of 2-6 L/min and at Pump Speeds up to 3000 rpm. Under pulsatile operating conditions, for each LVAD operating at a particular Pump Speed, an counterclockwise loop was inscribed in the HQ domain during a simulated cardiac cycle (HQ loop); this showed that there was a variable phase relationship between LVAD differential pressure and LVAD flow. For both the HMII and HVAD, increasing Pump Speed was associated with a right-hand and upward shift of the HQ loop and simulation of impairment of left ventricular function was associated with a decrease in loop area. During clinical use, not only does the pressure differential across the LVAD and its flow rate vary continuously, but their phase relationship is variable. This behavior is inadequately described by the widely accepted representation of a plot of pressure differential versus flow derived under steady conditions. We conclude that the dynamic HQ loop is a more meaningful representation of clinical operating conditions than the widely accepted steady flow HQ curve.
-
relationship between Pump Speed and exercise capacity during heartmate ii left ventricular assist device support influence of residual left ventricular function
European Journal of Heart Failure, 2012Co-Authors: Mumin R. Noor, Christopher T. Bowles, Nicholas R. BannerAbstract:Aims Patients treated with a Thoratec HeartMate II left ventricular assist device (LVAD) are supported at a fixed Pump Speed. It is uncertain whether Pump Speed has a significant effect on exercise capacity. We investigated the relationship between Pump Speed and exercise capacity and the influence of residual LV function Methods and results We exercised 30 patients 6 months after HeartMate II implantation at clinical Pump Speed (typically 9000 r.p.m.) and again at the lowest Speed available (6000 r.p.m.). Overall, peak oxygen uptake (pkVO2) positively correlated with LV ejection fraction (LVEF) both at the clinical Pump Speed (r = 0.41, P = 0.03) and after Pump Speed reduction (r = 0.50, P = 0.01). We divided the patients into two groups; those with higher LVEF (LVEF ≥40%) and those with lower LVEF (LVEF <40%) at the time of exercise testing. The response to Speed change was different between the two groups. In the higher LVEF group, the impact of LVAD Pump Speed reduction was minimal (pkVO2 21.4 ± 4.8 mL/kg/min vs. 20.8 ± 5.5 mL/kg/min, P = 0.38). In the lower LVEF group, the pkVO2 was lower at both Speeds; 17.2 ± 5.3 and 14.7 ± 5.9 mL/kg/min, respectively. In the lower LVEF group, the pkVO2 decreased by 2.5 mL/kg/min (P = 0.02) with Speed reduction. Conclusions HeartMate II patients with lower residual LV function had a lower pkVO2 and were more sensitive to Pump Speed reduction. This suggests that modulation of LVAD Speed during exercise could be of benefit to this group of patients.
-
Relationship between Pump Speed and exercise capacity during HeartMate II left ventricular assist device support: influence of residual left ventricular function
European Journal of Heart Failure, 2012Co-Authors: Mumin R. Noor, Christopher T. Bowles, Nicholas R. BannerAbstract:Aims Patients treated with a Thoratec HeartMate II left ventricular assist device (LVAD) are supported at a fixed Pump Speed. It is uncertain whether Pump Speed has a significant effect on exercise capacity. We investigated the relationship between Pump Speed and exercise capacity and the influence of residual LV function Methods and results We exercised 30 patients 6 months after HeartMate II implantation at clinical Pump Speed (typically 9000 r.p.m.) and again at the lowest Speed available (6000 r.p.m.). Overall, peak oxygen uptake (pkVO2) positively correlated with LV ejection fraction (LVEF) both at the clinical Pump Speed (r = 0.41, P = 0.03) and after Pump Speed reduction (r = 0.50, P = 0.01). We divided the patients into two groups; those with higher LVEF (LVEF ≥40%) and those with lower LVEF (LVEF
Yu Wang - One of the best experts on this subject based on the ideXlab platform.
-
A Sensorless Rotational Speed-Based Control System for Continuous Flow Left Ventricular Assist Devices
IEEE Transactions on Biomedical Engineering, 2020Co-Authors: Moustafa Meki, Yu Wang, Palaniappan Sethu, Mohammed Ghazal, Guruprasad GiridharanAbstract:Objective: Continuous Flow Left Ventricular Assist Devices (CFLVAD) are circulatory support devices that are implanted in patients with end-stage heart failure. We developed a novel control algorithm for CFLVAD to maintain physiologic perfusion while avoiding ventricular suction using only the intrinsic Pump measurement of Pump Speed and without utilizing model-based estimation. Methods: The controller objective is to maintain a differential Pump Speed setpoint. A mathematical model of the circulatory system coupled with a model of a CFLVAD was used to test the control algorithm in silico. Robustness and efficacy were evaluated by comparing the proposed control algorithm to constant Speed control, differential Pump pressure control, mean aortic pressure control, and ventricular end diastolic pressure control during (1) rest and exercise conditions, (2) a rapid eight-fold increase in pulmonary vascular resistance under rest and exercise, (3) transitions from rest to exercise, and exercise to rest, (4) safe mode during left ventricular asystole, and (5) RPM measurement noise of 1% to 10% for (1) to (4). Results and conclusion: The control algorithm provided adequate perfusion while preventing ventricular suction for all test conditions. Performance did not deteriorate significantly with Pump Speed measurement noise of up to 6%. The safe mode successfully detected asystole and maintained adequate perfusion to sustain life even when the differential Pump Speed was low. Significance: Maintaining a constant differential Pump Speed can simultaneously achieve physiologic perfusion and suction prevention without needing unreliable, direct measurements of flow or pressure, or complex parameter or model-based estimation techniques.
-
A Sensorless non-linear Control algorithm for Continuous Flow Right Ventricular Assist Devices
2018 IEEE International Symposium on Signal Processing and Information Technology (ISSPIT), 2018Co-Authors: Moustafa Meki, Yu Wang, Palaniappan Sethu, Mohammed Ghazal, Guruprasad GiridharanAbstract:Continuous flow right ventricular assist devices are mechanical circulatory support devices that are implanted in patients with end-stage heart failure. Right-sided heart failure often occurs in conjunction with the left-sided heart failure or can occur on its own as a result of heart attacks, dilated and hypertrophic cardiomyopathy or valvular diseases. Here, we propose a control algorithm for a continuous flow assist right ventricular assist devices that can maintain physiologic perfusion and avoid ventricular suction under various physical conditions using only the intrinsic Pump Speed. The algorithm maintains a differential Pump Speed setpoint using a proportional-integral controller. To test the robustness of the proposed algorithm, we used a previously validated mathematical model of the circulatory system coupled with a model of a continuous flow ventricular assist device to test the control algorithm in-silico. The robustness and efficacy were evaluated by comparing the control algorithm to constant Speed control during (1) rest condition, (2) exercise conditions, and (3) a rapid 30% increase in vena caval resistance during rest. The proposed algorithm performance was compared to the clinical constant Speed control under these condtions. The proposed differential Speed algorithm provided adequate perfusion by varying Pump Speed and flow while preventing ventricular suction for all test conditions. This algorithm does not require unreliable sensors, complicated parameter estimations, or any modifications to the Pump and can readily be applied to current devices.
-
Modeling of a New Sensorless Suction Detection System for the Rotary Left Ventricular Assist Device
2018 9th International Conference on Information Technology in Medicine and Education (ITME), 2018Co-Authors: Jing Peng, Anhua Lu, Yu WangAbstract:The rotary left ventricular assist device (LVAD) has been successfully and clinically used for congestive heart failure patients. However, patients may be at significant risk for ventricular suction while using a LVAD. Suction may lead to ventricular collapse when the blood Pump of the LVAD is working at higher rotational Speeds to draw more blood than available. Some suction detection systems typically required the external implantation of sensors, which were not reliable for long-term use because of failure, baseline drift, and short lifespan of sensors. In this study, a new sensorless suction detection system only using the intrinsic Pump parameter (Pump Speed) to eliminate all external sensors is proposed. Three features (suction indicators) are extracted from the Pump Speed signals without and with measurement noise and adopted as inputs to different classifiers. Two Pumping states as no suction or suction are classified with each classifier. The in-silico results with a combined human circulatory system and LVAD model show that the proposed strategy can detect ventricular suction effectively with high accuracy and stability. It could provide theoretical basis and technology support for developing the LVAD controller with high reliability.
-
Mixed sensitivity H∞ controller design for variable-Speed Pump-controlled motor system
2014 IEEE International Conference on Mechatronics and Automation, 2014Co-Authors: Xiaolin Li, Xiangzhou Wang, Yu WangAbstract:This paper focuses on constant Speed control of variable Speed Pump controlled motor system. The nonlinear model of Pump controlled motor system is derived and its parametric perturbations are taken into consideration. To decouple Pump Speed variation from H∞ controller, a closed loop flow rate controller of hydraulic Pump based on Bang-Bang control and low pass filter is proposed. Mixed sensitivity H∞ controller with load torque observer is achieved to reduce maximum Speed error and settling time of hydraulic motor. Simulation results show that the proposed control scheme is superior to PID controller.
-
Adaptive dynamic surface controller design of variable-Speed Pump controlled motor system with parametric uncertainties
The 26th Chinese Control and Decision Conference (2014 CCDC), 2014Co-Authors: Xiaolin Li, Xiangzhou Wang, Yu WangAbstract:The constant Speed control of variable Speed Pump controlled motor system is discussed in this paper. A dynamic surface controller is chosen to improve robustness of motor Speed when rotational Speed of variable Pump is time-varying. In the presence of bounded parametric uncertainties, an adaptive control scheme with parameter estimation is presented. Load torque used in dynamic surface controller is observed via reduced order observer. The simulation results show that the proposed control scheme is robust to bounded parametric uncertainties. Adaptive dynamic surface control has a better rejection performance of Pump Speed variation and load torque disturbance than PID control.
Mumin R. Noor - One of the best experts on this subject based on the ideXlab platform.
-
investigation of the characteristics of heartware hvad and thoratec heartmate ii under steady and pulsatile flow conditions
Artificial Organs, 2016Co-Authors: Mumin R. Noor, Christopher T. Bowles, Nicholas R. Banner, Chong H Ho, Kim H Parker, Andre R SimonAbstract:The aim of this study was to elucidate the dynamic characteristics of the Thoratec HeartMate II (HMII) and the HeartWare HVAD (HVAD) left ventricular assist devices (LVADs) under clinically representative in vitro operating conditions. The performance of the two LVADs were compared in a normothermic, human blood-filled mock circulation model under conditions of steady (nonpulsatile) flow and under simulated physiologic conditions. These experiments were repeated using 5% dextrose in order to determine its suitability as a blood analog. Under steady flow conditions, for the HMII, approximately linear inverse LVAD differential pressure (H) versus flow (Q) relationships were observed with good correspondence between the results of blood and 5% dextrose under all conditions except at a Pump Speed of 9000 rpm. For the HVAD, the corresponding relationships were inverse curvilinear and with good correspondence between the blood-derived and 5% dextrose-derived relationships in the flow rate range of 2-6 L/min and at Pump Speeds up to 3000 rpm. Under pulsatile operating conditions, for each LVAD operating at a particular Pump Speed, an counterclockwise loop was inscribed in the HQ domain during a simulated cardiac cycle (HQ loop); this showed that there was a variable phase relationship between LVAD differential pressure and LVAD flow. For both the HMII and HVAD, increasing Pump Speed was associated with a right-hand and upward shift of the HQ loop and simulation of impairment of left ventricular function was associated with a decrease in loop area. During clinical use, not only does the pressure differential across the LVAD and its flow rate vary continuously, but their phase relationship is variable. This behavior is inadequately described by the widely accepted representation of a plot of pressure differential versus flow derived under steady conditions. We conclude that the dynamic HQ loop is a more meaningful representation of clinical operating conditions than the widely accepted steady flow HQ curve.
-
relationship between Pump Speed and exercise capacity during heartmate ii left ventricular assist device support influence of residual left ventricular function
European Journal of Heart Failure, 2012Co-Authors: Mumin R. Noor, Christopher T. Bowles, Nicholas R. BannerAbstract:Aims Patients treated with a Thoratec HeartMate II left ventricular assist device (LVAD) are supported at a fixed Pump Speed. It is uncertain whether Pump Speed has a significant effect on exercise capacity. We investigated the relationship between Pump Speed and exercise capacity and the influence of residual LV function Methods and results We exercised 30 patients 6 months after HeartMate II implantation at clinical Pump Speed (typically 9000 r.p.m.) and again at the lowest Speed available (6000 r.p.m.). Overall, peak oxygen uptake (pkVO2) positively correlated with LV ejection fraction (LVEF) both at the clinical Pump Speed (r = 0.41, P = 0.03) and after Pump Speed reduction (r = 0.50, P = 0.01). We divided the patients into two groups; those with higher LVEF (LVEF ≥40%) and those with lower LVEF (LVEF <40%) at the time of exercise testing. The response to Speed change was different between the two groups. In the higher LVEF group, the impact of LVAD Pump Speed reduction was minimal (pkVO2 21.4 ± 4.8 mL/kg/min vs. 20.8 ± 5.5 mL/kg/min, P = 0.38). In the lower LVEF group, the pkVO2 was lower at both Speeds; 17.2 ± 5.3 and 14.7 ± 5.9 mL/kg/min, respectively. In the lower LVEF group, the pkVO2 decreased by 2.5 mL/kg/min (P = 0.02) with Speed reduction. Conclusions HeartMate II patients with lower residual LV function had a lower pkVO2 and were more sensitive to Pump Speed reduction. This suggests that modulation of LVAD Speed during exercise could be of benefit to this group of patients.
-
Relationship between Pump Speed and exercise capacity during HeartMate II left ventricular assist device support: influence of residual left ventricular function
European Journal of Heart Failure, 2012Co-Authors: Mumin R. Noor, Christopher T. Bowles, Nicholas R. BannerAbstract:Aims Patients treated with a Thoratec HeartMate II left ventricular assist device (LVAD) are supported at a fixed Pump Speed. It is uncertain whether Pump Speed has a significant effect on exercise capacity. We investigated the relationship between Pump Speed and exercise capacity and the influence of residual LV function Methods and results We exercised 30 patients 6 months after HeartMate II implantation at clinical Pump Speed (typically 9000 r.p.m.) and again at the lowest Speed available (6000 r.p.m.). Overall, peak oxygen uptake (pkVO2) positively correlated with LV ejection fraction (LVEF) both at the clinical Pump Speed (r = 0.41, P = 0.03) and after Pump Speed reduction (r = 0.50, P = 0.01). We divided the patients into two groups; those with higher LVEF (LVEF ≥40%) and those with lower LVEF (LVEF
