1
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Straccia A, Chassagne F, Barbour MC, Beckman J, Li S, Mahr C, Aliseda A. A Computational Investigation of the Effects of Temporal Synchronization of Left Ventricular Assist Device Speed Modulation with the Cardiac Cycle on Intraventricular Hemodynamics. Ann Biomed Eng 2024; 52:1763-1778. [PMID: 38517620 DOI: 10.1007/s10439-024-03489-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Accepted: 03/07/2024] [Indexed: 03/24/2024]
Abstract
Patients with advanced heart failure are implanted with a left ventricular assist device (LVAD) as a bridge-to-transplantation or destination therapy. Despite advances in pump design, the risk of stroke remains high. LVAD implantation significantly alters intraventricular hemodynamics, where regions of stagnation or elevated shear stresses promote thrombus formation. Third generation pumps incorporate a pulsatility mode that modulates rotational speed of the pump to enhance in-pump washout. We investigated how the timing of the pulsatility mode with the cardiac cycle affects intraventricular hemodynamic factors linked to thrombus formation. Computational fluid dynamics simulations with Lagrangian particle tracking to model platelet behavior in a patient-specific left ventricle captured altered intraventricular hemodynamics due to LVAD implantation. HeartMate 3 incorporates a pulsatility mode that modulates the speed of the pump every two seconds. Four different timings of this pulsatility mode with respect to the cardiac cycle were investigated. A strong jet formed between the mitral valve and inflow cannula. Blood stagnated in the left ventricular outflow tract beneath a closed aortic valve, in the near-wall regions off-axis of the jet, and in a large counterrotating vortex near the anterior wall. Computational results showed good agreement with particle image velocimetry results. Synchronization of the pulsatility mode with peak systole decreased stasis, reflected in the intraventricular washout of virtual contrast and Lagrangian particles over time. Temporal synchronization of HeartMate 3 pulsatility with the cardiac cycle reduces intraventricular stasis and could be beneficial for decreasing thrombogenicity.
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Affiliation(s)
- Angela Straccia
- Department of Mechanical Engineering, University of Washington, Seattle, WA, USA.
| | | | - Michael C Barbour
- Department of Mechanical Engineering, University of Washington, Seattle, WA, USA
| | - Jennifer Beckman
- Division of Cardiology, University of Washington, Seattle, WA, USA
| | - Song Li
- Institute for Advanced Cardiac Care, Medical City Healthcare, Dallas, TX, USA
| | - Claudius Mahr
- Institute for Advanced Cardiac Care, Medical City Healthcare, Dallas, TX, USA
| | - Alberto Aliseda
- Department of Mechanical Engineering, University of Washington, Seattle, WA, USA
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2
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Martinez J, Smegner K, Tomoda M, Motomura T, Chivukula VK. Encouraging Regular Aortic Valve Opening for EVAHEART 2 LVAD Support Using Virtual Patient Hemodynamic Speed Modulation Analysis. ASAIO J 2024; 70:207-216. [PMID: 38029749 DOI: 10.1097/mat.0000000000002093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2023] Open
Abstract
This study focuses on investigating the EVAHEART 2 left ventricular assist device (LVAD) toward designing optimal pump speed modulation (PSM) algorithms for encouraging aortic valve (AV) flow. A custom-designed virtual patient hemodynamic model incorporating the EVAHEART 2 pressure-flow curves, cardiac chambers, and the systemic and pulmonary circulations was developed and used in this study. Several PSM waveforms were tested to evaluate their influence on the mean arterial pressure (MAP), cardiac output (CO), and AV flow for representative heart failure patients. Baseline speeds were varied from 1,600 to 2,000 rpm. For each baseline speed, the following parameters were analyzed: 1) PSM ratio (reduced speed/baseline speed), 2) PSM duration (3-7 seconds), 3) native ventricle contractility, and 4) patient MAP of 70 and 80 mm Hg. More than 2,000 rpm virtual patient scenarios were explored. A lower baseline speed (1,600 and 1,700 rpm) produced more opportunities for AV opening and more AV flow. Higher baseline speeds (1,800 and 2,000 rpm) had lower or nonexistent AV flow. When analyzing PSM ratios, a larger reduction in speed (25%) over a longer PSM (5+ seconds) duration produced the most AV flow. Lower patient MAP and increased native ventricle contractility also contributed to improving AV opening frequency and flow. This study of the EVAHEART 2 LVAD is the first to focus on leveraging PSM to enhance pulsatility and encourage AV flow. Increased AV opening frequency can benefit aortic root hemodynamics, thereby improving patient outcomes.
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Affiliation(s)
- Jasmine Martinez
- From the Department of Biomedical Engineering and Science, Florida Institute of Technology, Melbourne, Florida
| | | | | | | | - Venkat Keshav Chivukula
- From the Department of Biomedical Engineering and Science, Florida Institute of Technology, Melbourne, Florida
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3
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Chassagne F, Beckman JA, Li S, Mahr C, Aliseda A. In Vitro Investigation of the Effect of the Timing of Left Ventricular Assist Device Speed Modulation on Intraventricular Flow Patterns. ASAIO J 2023; 69:533-543. [PMID: 36881637 PMCID: PMC11187697 DOI: 10.1097/mat.0000000000001893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2023] Open
Abstract
Thromboembolic events remain a common complication for left ventricular assist device (LVAD) patients. To prevent in-pump thrombosis, third-generation LVADs use speed modulation, which is not synchronized with the native left ventricle (LV) contractility. This study aims to investigate the effect of speed modulation on intraventricular flow patterns, and specifically, the impact of timing relative to pressure variations in the LV. Stereo-particle image velocimetry measurements were performed in a patient-derived LV implanted with an LVAD, for different timings of the speed modulation and speed. Speed modulation has a strong effect on instantaneous afterload and flowrate (-16% and +20%). The different timings of the speed modulation resulted in different flowrate waveforms, exhibiting different maxima (5.3-5.9 L/min, at constant average flowrate). Moreover, the timing of the speed modulation was found to strongly influence intraventricular flow patterns, specifically, stagnation areas within the LV. These experiments highlight, once more, the complex relationship between LVAD speed, hemodynamic resistance, and intraventricular pressure. Overall, this study demonstrates the importance of considering native LV contractility in future LVAD controls, to improve hemocompatibility and reduce the risk of thromboembolic complications.
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Affiliation(s)
- Fanette Chassagne
- Mines Saint-Etienne, Univ Jean Monnet, INSERM, U 1059 Sainbiose, F - 42023 Saint-Etienne France
| | | | - Song Li
- Division of Cardiology, University of Washington, Seattle, WA, USA
| | - Claudius Mahr
- Division of Cardiology, University of Washington, Seattle, WA, USA
| | - Alberto Aliseda
- Mechanical Engineering, University of Washington, Seattle, WA, USA
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4
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Zhao X, Zhao L, Xu J, Li D, Li H, Li Y, Chen H, Zhang Y. Aortic valve opening in mock-loop with continuous-flow left ventricular assist device. Int J Artif Organs 2022; 45:809-816. [PMID: 35818176 DOI: 10.1177/03913988221111811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The appropriate opening of aortic valves is crucial for heart failure (HF) patients with left ventricular assist devices (LVADs). Nevertheless, up to the present time, aortic valve monitoring has not been performed in discharged patients. In this study, a mock-loop platform was developed to investigate the aortic valve performance in LVAD patients. An additional sluice valve was placed next to the aortic valve that when the sluice valve is manually closed, the aortic valve will remain closed; when the sluice valve is open, the aortic valve is opened or closed upon the pressures. The results showed that when the LVAD speed was below 2600 rpm, the aortic valve can be intermittently opened, while when the LVAD speed was over 2600 rpm, the aortic valve was persistently closed. The left ventricular end-systolic pressure (LVESP) was found to be an indicator of aortic valve closure that, upon the aortic valve closure LVESP suddenly decreased. The LVESP is suggested for future monitoring the status of the aortic valve for patients with implanted LVADs. The effects of heart failure (HF) degrees, circulation resistance, and aortic compliance on aortic valve closure were further studied. The results revealed that LVAD implantation in patients with early HF degrees will help to avoid persistent aortic valve closure.
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Affiliation(s)
- Xiang Zhao
- School of Medicine, Tsinghua University (School of Medicine) - RocketHeart Co. Ltd Joint Research Center for Artificial Heart, Tsinghua University, Beijing, China.,School of Mechanical Engineering, State Key Laboratory of Tribology, Tsinghua University, Beijing, China
| | - Luxiang Zhao
- School of Medicine, Tsinghua University (School of Medicine) - RocketHeart Co. Ltd Joint Research Center for Artificial Heart, Tsinghua University, Beijing, China.,School of Mechanical Engineering, State Key Laboratory of Tribology, Tsinghua University, Beijing, China
| | - Jian Xu
- School of Medicine, Tsinghua University (School of Medicine) - RocketHeart Co. Ltd Joint Research Center for Artificial Heart, Tsinghua University, Beijing, China
| | - Donghai Li
- Advanced Medical Research Institute, Shandong University, Shandong, China
| | - Heping Li
- Department of Engineering Physics, Tsinghua University, Beijing, China
| | - Yongjian Li
- School of Mechanical Engineering, State Key Laboratory of Tribology, Tsinghua University, Beijing, China
| | - Haosheng Chen
- School of Mechanical Engineering, State Key Laboratory of Tribology, Tsinghua University, Beijing, China
| | - Yu Zhang
- School of Medicine, Tsinghua University (School of Medicine) - RocketHeart Co. Ltd Joint Research Center for Artificial Heart, Tsinghua University, Beijing, China
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5
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Stapor M, Pilat A, Gackowski A, Misiuda A, Gorkiewicz-Kot I, Kaleta M, Kleczynski P, Zmudka K, Legutko J, Kapelak B, Wierzbicki K. Echo-guided left ventricular assist device speed optimisation for exercise maximisation. Heart 2022; 108:1055-1062. [PMID: 35314453 PMCID: PMC9209671 DOI: 10.1136/heartjnl-2021-320495] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 02/24/2022] [Indexed: 11/29/2022] Open
Abstract
Objective Current generation left ventricular assist devices (LVADs) operate with a fixed rotation speed and no automated speed adjustment function. This study evaluates the concept of physiological pump speed optimisation based on aortic valve opening (AVO) imaging during a cardiopulmonary exercise test (CPET). Methods This prospective crossover study (NCT05063006) enrolled patients with implanted third-generation LVADs with hydrodynamic bearing. After resting speed optimisation, patients were randomised to a fixed-modified speed or modified-fixed speed CPET sequence. Fixed speed CPET maintained baseline pump settings. During the modified speed CPET, the LVAD speed was continuously altered to preserve periodic AVO. Results We included 22 patients, the mean age was 58.4±7 years, 4.5% were women and 54.5% had ischaemic cardiomyopathy. Exertional AVO assessment was feasible in all subjects. Maintaining periodic AVO allowed to safely raise the pump speed from 2900 (IQR 2640–3000) to 3440 revolutions per minute (RPM) (IQR 3100–3700; p<0.001). As a result, peak oxygen consumption increased from 11.1±2.4 to 12.8±2.8 mL/kg/min (p<0.001) and maximum workload from 1.1 (IQR 0.9–1.5) to 1.2 W/kg (IQR 0.9–1.7; p=0.028). The Borg scale exertion level decreased from 15.2±1.5 to 13.5±1.2 (p=0.005). Conclusions Transthoracic AVO imaging is possible during CPETs in patients with LVAD. Dynamic echo-guided pump speed adjustment based on the AVO improves exercise tolerance and augments peak oxygen consumption and maximum workload.
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Affiliation(s)
- Maciej Stapor
- Department of Interventional Cardiology, John Paul II Hospital, Krakow, Malopolska, Poland
| | - Adam Pilat
- Department of Automatic Control and Robotics, AGH University of Science and Technology, Krakow, Poland
| | - Andrzej Gackowski
- Department of Coronary Disease and Heart Failure, Jagiellonian University Medical College, Faculty of Medicine, Institute of Cardiology, Krakow, Poland
| | - Agnieszka Misiuda
- Noninvasive Cardiovascular Laboratory, John Paul II Hospital, Krakow, Poland
| | - Izabela Gorkiewicz-Kot
- Department of Cardiovascular Surgery and Transplantology, John Paul II Hospital, Krakow, Poland
| | - Michal Kaleta
- Department of Cardiovascular Surgery and Transplantology, John Paul II Hospital, Krakow, Poland
| | - Pawel Kleczynski
- Department of Interventional Cardiology, Jagiellonian University Medical College, Faculty of Medicine, Institute of Cardiology, Krakow, Poland
| | - Krzysztof Zmudka
- Department of Interventional Cardiology, Jagiellonian University Medical College, Faculty of Medicine, Institute of Cardiology, Krakow, Poland
| | - Jacek Legutko
- Department of Interventional Cardiology, Jagiellonian University Medical College, Faculty of Medicine, Institute of Cardiology, Krakow, Poland
| | - Boguslaw Kapelak
- Department of Cardiovascular Surgery and Transplantology, Jagiellonian University Medical College, Faculty of Medicine, Institute of Cardiology, Krakow, Poland
| | - Karol Wierzbicki
- Department of Cardiovascular Surgery and Transplantology, Jagiellonian University Medical College, Faculty of Medicine, Institute of Cardiology, Krakow, Poland
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6
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Jing T, Xin T, Wang F, Zhang Z, Zhou L. Control Strategy Design of a Microblood Pump Based on Heart-Rate Feedback. MICROMACHINES 2022; 13:mi13030358. [PMID: 35334650 PMCID: PMC8951086 DOI: 10.3390/mi13030358] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 02/19/2022] [Accepted: 02/21/2022] [Indexed: 11/16/2022]
Abstract
Based on the nonlinear relationship between heart rate and stroke volume, a flow model of left ventricular circulation was improved, and a variable-speed blood-pump control strategy based on heart-rate feedback was proposed. The control strategy was implemented on a system combining the rotary blood pump and blood circulation models of heart failure. The aortic flow of a healthy heart at different heart rates was the desired control goal. Changes in heart rate were monitored and pump speed was adjusted so that the output flow and aortic pressure of the system would match a normal heart in real time to achieve the best auxiliary state. After simulation with MATLAB, the cardiac output satisfied the ideal perfusion requirements at different heart rates, and aortic pressure demonstrated lifting and had good pulsatile performance when a variable-speed blood pump was used. The coupled model reflected the relationship between hemodynamic parameters at different heart rates with the use of the variable-speed blood pump, providing a theoretical basis for the blood-pump-assisted treatment of heart failure and the design of physiological control strategies.
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Affiliation(s)
| | | | | | | | - Ling Zhou
- Correspondence: ; Tel.: +86-138-1547-7737
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7
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Ferrari G, Di Molfetta A, Zieliński K, Cusimano V, Darowski M, Kozarski M, Fresiello L. Assessment of the VAD – Native ventricle pumping system by an equivalent pump: A computational model based procedure. Biocybern Biomed Eng 2021. [DOI: 10.1016/j.bbe.2021.05.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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8
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HeartWare HVAD Flow Estimator Accuracy for Left and Right Ventricular Support. ASAIO J 2021; 67:416-422. [PMID: 33769996 DOI: 10.1097/mat.0000000000001247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
This study investigated the accuracy of the HeartWare HVAD flow estimator for left ventricular assist device (LVAD) support and biventricular assist device (BiVAD) support for modes of reduced speed (BiVAD-RS) and banded outflow (BiVAD-B). The HVAD flow estimator was evaluated in a mock circulatory loop under changes in systemic and pulmonary vascular resistance, heart rate, central venous pressure, and simulated hematocrit (correlated to viscosity). A difference was found between mean estimated and mean measured flow for LVAD (0.1 ± 0.3 L/min), BiVAD-RS (-0.1 ± 0.2 L/min), and BiVAD-B (0 ± 0.2 L/min). Analysis of the flow waveform pulsatility showed good correlation for LVAD (r2 = 0.98) with a modest spread in error (0.7 ± 0.1 L/min), while BiVAD-RS and BiVAD-B showed similar spread in error (0.7 ± 0.3 and 0.7 ± 0.2 L/min, respectively), with much lower correlation (r2 = 0.85 and r2 = 0.60, respectively). This study demonstrated that the mean flow error of the HVAD flow estimator is similar when the device is used in LVAD, BiVAD-RS, or BiVAD-B configuration. However, the instantaneous flow waveform should be interpreted with caution, particularly in the cases of BiVAD support.
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9
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Jain P, Adji A, Emmanuel S, Robson D, Muthiah K, Macdonald PS, Hayward CS. Phenotyping of Stable Left Ventricular Assist Device Patients Using Noninvasive Pump Flow Responses to Acute Loading Transients. J Card Fail 2021; 27:642-650. [PMID: 33497807 DOI: 10.1016/j.cardfail.2021.01.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 01/10/2021] [Accepted: 01/11/2021] [Indexed: 11/27/2022]
Abstract
BACKGROUND Although it has been established that continuous flow left ventricular assist devices are sensitive to loading conditions, the effect of acute load and postural changes on pump flow have not been explored systematically. METHODS AND RESULTS Fifteen stable outpatients were studied. Patients sequentially transitioned from the seated position to supine, passive leg raise, and standing with transition effects documented. A modified Valsalva maneuver, consisting of a forced expiration with an open glottis, was performed in each position. A sustained, 2-handed handgrip was performed in the supine position. The pump flow waveform was recorded continuously and left ventricular end-diastolic diameter measured during each stage using transthoracic echocardiography. Transitioning from seated to supine posture produced a significant increase in the flow and the ventricular end-diastolic diameter, consistent with an increased preload. The transition from supine to standing produced a transient increase in the mean flow and decreased the flow pulsatility index. At steady state, these changes were reversed with a decrease in the mean and trough flow and increased pulsatility index, consistent with venous redistribution and possible baroreflex compensation. Four distinct patterns of standing-induced flow waveform effects were identified, reflecting varying preload, afterload, and individual compensatory effects. A sustained handgrip produced a significant decrease in flow and increase in flow pulsatility across all patients, reflecting an increased afterload pressure. A modified Valsalva maneuver produced a decrease in the flow pulsatility while seated, supine, and standing, but not during leg raise. Five patterns of pulsatility effect during Valsalva were observed: (1) minimal change, (2) pulsatility recovery, (3) rapid flatline, (4) slow flatline with delayed flow recovery, and (5) primary suction. CONCLUSIONS Acute disturbances in loading conditions produce heterogeneous pump flow responses reflecting their complex interactions with pump and ventricular function as well as reflex compensatory mechanisms. Differences in responses and individual variabilities have significant implications for automated pump control algorithms.
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Affiliation(s)
- Pankaj Jain
- Heart Failure and Transplant Unit, Cardiology Department, St Vincent's Hospital, Sydney, Australia; University of New South Wales, Sydney, Australia
| | - Audrey Adji
- Heart Failure and Transplant Unit, Cardiology Department, St Vincent's Hospital, Sydney, Australia
| | - Sam Emmanuel
- Heart Failure and Transplant Unit, Cardiology Department, St Vincent's Hospital, Sydney, Australia; University of New South Wales, Sydney, Australia
| | - Desiree Robson
- Heart Failure and Transplant Unit, Cardiology Department, St Vincent's Hospital, Sydney, Australia
| | - Kavitha Muthiah
- Heart Failure and Transplant Unit, Cardiology Department, St Vincent's Hospital, Sydney, Australia
| | - Peter S Macdonald
- Heart Failure and Transplant Unit, Cardiology Department, St Vincent's Hospital, Sydney, Australia; University of New South Wales, Sydney, Australia; Victor Chang Cardiac Research Institute, Sydney, Australia
| | - Christopher S Hayward
- Heart Failure and Transplant Unit, Cardiology Department, St Vincent's Hospital, Sydney, Australia; University of New South Wales, Sydney, Australia; Victor Chang Cardiac Research Institute, Sydney, Australia.
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10
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In Vitro Investigation of the Effect of Left Ventricular Assist Device Speed and Pulsatility Mode on Intraventricular Hemodynamics. Ann Biomed Eng 2020; 49:1318-1332. [PMID: 33128182 DOI: 10.1007/s10439-020-02669-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 10/20/2020] [Indexed: 10/23/2022]
Abstract
Stroke has become the main cause of mortality and morbidity in patients treated with Left Ventricular Assist Devices (LVADs). The hemodynamics of the left ventricle are altered by the implantation of an LVAD, with the increase of thrombogenic flow patterns, such as stagnation regions. Time-resolved stereo particle image velocimetry (Stereo-PIV) measurements of the flow inside a patient-specific model of the left ventricle (LV) implanted with an LVAD were performed. The effects of LVAD speed, peripheral resistance and afterload were investigated. The impact of activating the LVAD pulsatility mode (periodic speed modulation) was also evaluated. Analysis of the velocity measurements in two orthogonal planes revealed stagnation zones which may be favorable to thrombus formation. Increasing LVAD speed, despite increasing the flow rate through the inflow cannula, does not automatically result in smaller stagnation regions. These results demonstrated the strong interdependence of peripheral resistance, afterload and flow through the LVAD. As a consequence, the pulsatility mode showed very limited effect on overall flow rate. However, it did reduce the size of high stagnation areas. This study showed how LVAD speed, peripheral resistance and afterload impact the complex intraventricular flow patterns in a ventricle implanted with an LVAD and quantify their thrombogenic risk.
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11
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Malchesky PS. Artificial Organs
2019: A year in review. Artif Organs 2020; 44:314-338. [DOI: 10.1111/aor.13650] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 01/14/2020] [Accepted: 01/14/2020] [Indexed: 12/13/2022]
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12
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Leao T, Utiyama B, Fonseca J, Bock E, Andrade A. In vitro evaluation of multi-objective physiological control of the centrifugal blood pump. Artif Organs 2020; 44:785-796. [PMID: 31944337 DOI: 10.1111/aor.13639] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2019] [Revised: 01/04/2020] [Accepted: 01/07/2020] [Indexed: 12/20/2022]
Abstract
Left ventricular assist devices (LVADs) have been used as a bridge to transplantation or as destination therapy to treat patients with heart failure (HF). The inability of control strategy to respond automatically to changes in hemodynamic conditions can impact the patients' quality of life. The developed control system/algorithm consists of a control system that harmoniously adjusts pump speed without additional sensors, considering the patient's clinical condition and his physical activity. The control system consists of three layers: (a) Actuator speed control; (b) LVAD flow control (FwC); and (c) Fuzzy control system (FzC), with the input variables: heart rate (HR), mean arterial pressure (MAP), minimum pump flow, level of physical activity (data from patient), and clinical condition (data from physician, INTERMACS profile). FzC output is the set point for the second LVAD control schemer (FwC) which in turn adjusts the speed. Pump flow, MAP, and HR are estimated from actuator drive parameters (speed and power). Evaluation of control was performed using a centrifugal blood pump in a hybrid cardiovascular simulator, where the left heart function is the mechanical model and right heart function is the computational model. The control system was able to maintain MAP and cardiac output in the physiological level, even under variation of EF. Apart from this, also the rotational pump speed is adjusted following the simulated clinical condition. No backflow from the aorta in the ventricle occurred through LVAD during tests. The control algorithm results were considered satisfactory for simulations, but it still should be confirmed during in vivo tests.
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Affiliation(s)
- Tarcisio Leao
- Department of Electric, Federal Institute of Sao Paulo, Sao Paulo, Brazil.,Department of Bioengineering, Institute Dante Pazzanese of Cardiology, Sao Paulo, Brazil
| | - Bruno Utiyama
- Department of Bioengineering, Institute Dante Pazzanese of Cardiology, Sao Paulo, Brazil.,Bioengineering, University Sao Judas Tadeu, Sao Paulo, Brazil
| | - Jeison Fonseca
- Department of Bioengineering, Institute Dante Pazzanese of Cardiology, Sao Paulo, Brazil.,Bioengineering, University Sao Judas Tadeu, Sao Paulo, Brazil
| | - Eduardo Bock
- Department of Mechanic, Federal Institute of Sao Paulo, Sao Paulo, Brazil
| | - Aron Andrade
- Department of Bioengineering, Institute Dante Pazzanese of Cardiology, Sao Paulo, Brazil.,Bioengineering, University Sao Judas Tadeu, Sao Paulo, Brazil.,University of Sao Paulo, IDPC/USP, Sao Paulo, Brazil
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13
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Jain P, Shehab S, Muthiah K, Robson D, Granegger M, Drakos SG, Jansz P, Macdonald PS, Hayward CS. Insights Into Myocardial Oxygen Consumption, Energetics, and Efficiency Under Left Ventricular Assist Device Support Using Noninvasive Pressure-Volume Loops. Circ Heart Fail 2019; 12:e006191. [DOI: 10.1161/circheartfailure.119.006191] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background:
Assessment of left ventricular (LV) recovery under continuous-flow LV assist device therapy is hampered by concomitant pump support. We describe derivation of noninvasive pressure-volume loops in continuous-flow LV assist device patients and demonstrate an application in the assessment of recovery.
Methods and Results:
Using pump controller parameters and noninvasive arterial pressure waveforms, central aortic pressure, outflow conduit pressure gradient, and instantaneous LV pressure were calculated. Instantaneous LV volumes were calculated from echocardiographic LV end-diastolic volume accounting for the integral of pump flow with respect to time and aortic ejection volume derived from the pump speed waveform. Pressure-volume loops were derived during pump speed adjustment and following bolus intravenous milrinone to assess changes in loading conditions and contractility, respectively. Fourteen patients were studied. Baseline noninvasive LV end-diastolic pressure correlated with invasive pulmonary arterial wedge pressure (
r
2
=0.57, root mean square error 5.0 mm Hg,
P
=0.003). Measured noninvasively, milrinone significantly increased LV ejection fraction (40.3±13.6% versus 36.8±14.2%,
P
<0.0001), maximum dP/dt (623±126 versus 555±122 mm Hg/s,
P
=0.006), and end-systolic elastance (1.03±0.57 versus 0.89±0.38 mm Hg/mL,
P
=0.008), consistent with its expected inotropic effect. Milrinone reduced myocardial oxygen consumption (0.15±0.06 versus 0.16±0.07 mL/beat,
P
=0.003) and improved myocardial efficiency (43.7±14.0% versus 41.2±15.5%,
P
=0.001). Reduced pump speed caused increased LV end-diastolic volume (190±80 versus 165±71 mL,
P
<0.0001) and LV end-diastolic pressure (14.3±10.2 versus 9.9±9.3 mm Hg,
P
=0.024), consistent with a predictable increase in preload. There was increased myocardial oxygen consumption (0.16±0.07 versus 0.14±0.06 mL O
2
/beat,
P
<0.0001) despite unchanged stroke work (
P
=0.24), reflecting decreased myocardial efficiency (39.2±12.7% versus 45.2±17.0%,
P
=0.003).
Conclusions:
Pressure-volume loops are able to be derived noninvasively in patients with the HeartWare HVAD and can detect induced changes in load and contractility.
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Affiliation(s)
- Pankaj Jain
- Cardiology Department, St Vincent’s Hospital, Sydney, Australia (P.J., S.S., K.M., D.R., P.J., P.S.M., C.S.H.)
| | - Sajad Shehab
- Cardiology Department, St Vincent’s Hospital, Sydney, Australia (P.J., S.S., K.M., D.R., P.J., P.S.M., C.S.H.)
| | - Kavitha Muthiah
- Cardiology Department, St Vincent’s Hospital, Sydney, Australia (P.J., S.S., K.M., D.R., P.J., P.S.M., C.S.H.)
| | - Desiree Robson
- Cardiology Department, St Vincent’s Hospital, Sydney, Australia (P.J., S.S., K.M., D.R., P.J., P.S.M., C.S.H.)
| | - Marcus Granegger
- Institute for Imaging Science and Computational Modelling in Cardiovascular Medicine, Charitè Universitätsmedizin, Berlin, Germany (M.G.)
| | | | - Paul Jansz
- Cardiology Department, St Vincent’s Hospital, Sydney, Australia (P.J., S.S., K.M., D.R., P.J., P.S.M., C.S.H.)
| | - Peter S. Macdonald
- Cardiology Department, St Vincent’s Hospital, Sydney, Australia (P.J., S.S., K.M., D.R., P.J., P.S.M., C.S.H.)
| | - Christopher S. Hayward
- Cardiology Department, St Vincent’s Hospital, Sydney, Australia (P.J., S.S., K.M., D.R., P.J., P.S.M., C.S.H.)
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Jain P, Muthiah K, Shehab S, Robson D, Hayward CS. Dynamic flow responses to expiratory maneuvers in left ventricular assist device patients. J Heart Lung Transplant 2019; 38:669-674. [DOI: 10.1016/j.healun.2019.02.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 01/25/2019] [Accepted: 02/20/2019] [Indexed: 10/27/2022] Open
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