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In Vivo Evaluation of a Novel Control Algorithm for Left Ventricular Assist Devices Based Upon Ventricular Stroke Work. ASAIO J 2023; 69:86-95. [PMID: 35420555 DOI: 10.1097/mat.0000000000001722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The physical fitness of patients with terminal heart failure and an implanted left ventricular assist device (LVAD) might be improved by load-adaptive control of the LVAD. In this study, three control strategies for LVAD were compared in eight pigs: (1) a constant stroke work (CSW) control strategy that ensures a constant ventricular load using ventricular stroke work as the control variable; (2) a work ratio (WR) controller that maintains a constant ratio of ventricular work to hydraulic pump work; and (3) a controller that maintains the pump pace at a constant speed (CS). Biventricular heart insufficiency was induced by increased isoflurane application, and preload, afterload, and contractility alterations were performed. LVAD speed changes were significantly more pronounced in all load interventions with the CSW control strategy (preload: P < 0.001 vs. CS and P = 0.004 vs. WR; afterload: P < 0.001 vs. CS and P < 0.001 vs. WR; contractility: P < 0.001 vs. CS and P < 0.001 vs. WR). However, a significant difference in systemic flow only became evident in the experiments upon afterload increase ( P < 0.001 vs. CS and P = 0.004 vs. WR). An implementation of an evolved version of the CSW control strategy that dispenses with invasively measured parameters might be feasible for clinical use.
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2
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A Flow Sensor-Based Suction-Index Control Strategy for Rotary Left Ventricular Assist Devices. SENSORS 2021; 21:s21206890. [PMID: 34696104 PMCID: PMC8541286 DOI: 10.3390/s21206890] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 09/28/2021] [Accepted: 10/13/2021] [Indexed: 11/29/2022]
Abstract
Rotary left ventricular assist devices (LVAD) have emerged as a long-term treatment option for patients with advanced heart failure. LVADs need to maintain sufficient physiological perfusion while avoiding left ventricular myocardial damage due to suction at the LVAD inlet. To achieve these objectives, a control algorithm that utilizes a calculated suction index from measured pump flow (SIMPF) is proposed. This algorithm maintained a reference, user-defined SIMPF value, and was evaluated using an in silico model of the human circulatory system coupled to an axial or mixed flow LVAD with 5–10% uniformly distributed measurement noise added to flow sensors. Efficacy of the SIMPF algorithm was compared to a constant pump speed control strategy currently used clinically, and control algorithms proposed in the literature including differential pump speed control, left ventricular end-diastolic pressure control, mean aortic pressure control, and differential pressure control during (1) rest and exercise states; (2) rapid, eight-fold augmentation of pulmonary vascular resistance for (1); and (3) rapid change in physiologic states between rest and exercise. Maintaining SIMPF simultaneously provided sufficient physiological perfusion and avoided ventricular suction. Performance of the SIMPF algorithm was superior to the compared control strategies for both types of LVAD, demonstrating pump independence of the SIMPF algorithm.
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3
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Korn L, Dual S, Rixen J, Meboldt M, Leonhardt S, Schmid Daners M, Walter M. Dual-modality Volume Measurement integrated on a Ventricular Assist Device. IEEE Trans Biomed Eng 2021; 69:1151-1161. [PMID: 34559630 DOI: 10.1109/tbme.2021.3115019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE Ventricular assist devices (VADs) are implanted in patients suffering from end-stage heart failure to sustain the blood circulation. Real-time volume measurement could be a valuable tool to monitor patients and enable physiological control strategies to provide individualized therapy. However, volume measurement using one sensor modality requires re-calibration in the critical time post VAD implantation. METHODS To overcome this limitation, we have integrated ultrasound and impedance volume measurement techniques into a cannula of an apical VAD. We tested both modalities across a volume range from 140-420 mL using two differently sized and shaped biventricular silicon heart phantoms, which were subjected to physiological pressures in an in-vitro test bench. We compared results from standard calibrated measurements with calculations found by a quadratic optimization for the single modality and their combination (dual-modality) and validated the results using twofold cross-validation. RESULTS The dual-modality approach resulted in most favorable limits of agreement (LOA) of -0.83 ± 1.54% compared to -13.88 ± 5.90% for ultrasound and -43.45 ± 10.28% for electric impedance, separately. CONCLUSION The results of the dual-modality approach were as accurate as the standard calibrated measurement and valid over a large range of volumes (140-420 mL). In this in-vitro study, we show how a dual-modality ventricular volume measurement of ultrasound and electric impedance increases the robustness and renders calibration obsolete. SIGNIFICANCE Ventricular volumes could be measured accurately in the critical period post VAD implantation despite ventricular remodeling.
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4
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Habigt MA, Gesenhues J, Ketelhut M, Hein M, Duschner P, Rossaint R, Mechelinck M. In vivo evaluation of two adaptive Starling-like control algorithms for left ventricular assist devices. ACTA ACUST UNITED AC 2020; 66:257-266. [PMID: 34062635 DOI: 10.1515/bmt-2020-0248] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 11/01/2020] [Indexed: 11/15/2022]
Abstract
The implantation of a left ventricular assist device (LVAD) is often the only therapy in terminal heart failure (HF). However, despite technical advancements, the physical fitness of the patients is still limited. One strategy to improve the benefits of ventricular assist device therapy might be the implementation of load adaptive control strategies. Two control strategies and a constant speed controller (CS) were implemented in an acute animal model where four healthy pigs received LVAD implantations. In the first strategy (preload recruitable stroke work [SW] controller, PRS), the desired pump work was computed in relation to the end-diastolic volume. In the second strategy, the controller was programmed to keep a fixed ratio of the mean hydraulic power of the assist device to the mean hydraulic power of the left ventricle (power relation controller, PR). Preload reduction, afterload increase experiments and short-term coronary artery occlusions were conducted to test the behavior of the control strategies under variable conditions. Within the experiments, the PR controller demonstrated the best preload sensitivity. The PRS controller had the best response to an increased afterload and to a reduced ventricular contractility in terms of effectively preventing ventricular overloading and increasing VAD support. No significant differences in systemic flow were observed.
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Affiliation(s)
- Moriz A Habigt
- Anaesthesiology Clinic, University Hospital RWTH Aachen, Aachen, Germany
| | - Jonas Gesenhues
- Institute of Automatic Control, RWTH Aachen University, Aachen, Germany
| | - Maike Ketelhut
- Institute of Automatic Control, RWTH Aachen University, Aachen, Germany
| | - Marc Hein
- Anaesthesiology Clinic, University Hospital RWTH Aachen, Aachen, Germany
| | - Patrick Duschner
- Anaesthesiology Clinic, University Hospital RWTH Aachen, Aachen, Germany
| | - Rolf Rossaint
- Anaesthesiology Clinic, University Hospital RWTH Aachen, Aachen, Germany
| | - Mare Mechelinck
- Anaesthesiology Clinic, University Hospital RWTH Aachen, Aachen, Germany
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5
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Stephens AF, Gregory SD, Burrell AJC, Marasco S, Stub D, Salamonsen RF. Physiological principles of Starling-like control of rotary ventricular assist devices. Expert Rev Med Devices 2020; 17:1169-1182. [PMID: 33094673 DOI: 10.1080/17434440.2020.1841631] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Introduction: This review explores the Starling-like physiological control method (SLC) for rotary ventricular assist devices (VADs) for severe heart failure. The SLC, based on mathematical models of the circulation, has two functions modeling each ventricle. The first function controls the output of the VAD to the arterial pool according to Starling's law, while the second function accounts for how the blood returns to the heart from the veins. The article aims to expose clinicians to SLC in an accessible and clinically relevant discussion. Areas Covered: The article explores the physiology underlying the controller, its development and how that physiology can be adapted to SLC. Examples of controller performance are demonstrated and discussed using a benchtop model of the cardiovascular system. A discussion of the limitations and criticisms of SLC is presented, followed by a future outlook on the clinical adoption of SLC. Expert Opinion: Due to its simplicity and emulation of the natural cardiac autoregulation, SLC is the superior physiological control method for rotary VADs. However, current technical and regulatory challenges prevent the clinical translation of SLC of VADs. Further technical and regulatory development will enable the clinical translation of SLCs of VADs in the coming years.
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Affiliation(s)
- Andrew F Stephens
- Department of Mechanical and Aerospace Engineering, Monash University , Melbourne, Australia.,Cardiorespiratory Engineering and Technology Laboratory, Baker Heart and Diabetes Institute , Melbourne, Australia
| | - Shaun D Gregory
- Department of Mechanical and Aerospace Engineering, Monash University , Melbourne, Australia.,Cardiorespiratory Engineering and Technology Laboratory, Baker Heart and Diabetes Institute , Melbourne, Australia
| | | | - Silvana Marasco
- Department of Cardiothoracic Surgery, Alfred Hospital , Melbourne, Australia
| | - Dion Stub
- Cardiorespiratory Engineering and Technology Laboratory, Baker Heart and Diabetes Institute , Melbourne, Australia.,Department of Cardiology, Alfred Hospital , Melbourne, Australia.,Department of Epidemiology and Preventive Medicine, Monash University , Melbourne, Australia
| | - Robert F Salamonsen
- Intensive Care Unit, Alfred Hospital , Melbourne, Australia.,Department of Epidemiology and Preventive Medicine, Monash University , Melbourne, Australia
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6
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Koh V, Pauls J, Wu E, Stevens M, Ho Y, Lovell N, Lim E. A centralized multi-objective model predictive control for a biventricular assist device: An in vitro evaluation. Biomed Signal Process Control 2020. [DOI: 10.1016/j.bspc.2020.101914] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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7
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Fixsen LS, Petterson NJ, Houthuizen P, Rutten MCM, van de Vosse FN, Lopata RGP. Ultrasound-based estimation of remaining cardiac function in LVAD-supported ex vivo hearts. Artif Organs 2020; 44:E326-E336. [PMID: 32242944 PMCID: PMC7496524 DOI: 10.1111/aor.13693] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 02/05/2020] [Accepted: 03/23/2020] [Indexed: 11/28/2022]
Abstract
Left ventricular assist devices (LVAD) provide cardiac support to patients with advanced heart failure. Methods that can directly measure remaining LV function following device implantation do not currently exist. Previous studies have shown that a combination of loading (LV pressure) and deformation (strain) measurements enables quantitation of myocardial work. We investigated the use of ultrasound (US) strain imaging and pressure–strain loop analysis in LVAD‐supported hearts under different hemodynamic and pump unloading conditions, with the aim of determining LV function with and without LVAD support. Ex vivo porcine hearts (n = 4) were implanted with LVADs and attached to a mock circulatory loop. Measurements were performed at hemodynamically defined “heart conditions” as the hearts deteriorated from baseline. Hemodynamic (including LV pressure) and radio‐frequency US data were acquired during a pump‐ramp protocol at speeds from 0 (with no pump outflow) to 10 000 revolutions per minute (rpm). Regional circumferential (εcirc) and radial (εrad) strains were estimated over each heart cycle. Regional ventricular dyssynchrony was quantitated through time‐to‐peak strain. Mean change in LV pulse pressure and εcirc between 0 and 10 krpm were −21.8 mm Hg and −7.24% in the first condition; in the final condition −46.8 mm Hg and −19.2%, respectively. εrad was not indicative of changes in pump speed or heart condition. Pressure–strain loops showed a degradation in the LV function and an increased influence of LV unloading: loop area reduced by 90% between 0 krpm in the first heart condition and 10 krpm in the last condition. High pump speeds and degraded condition led to increased dyssynchrony between the septal and lateral LV walls. Functional measurement of the LV while undergoing LVAD support is possible by using US strain imaging and pressure–strain loops. This can provide important information about remaining pump function. Use of novel LV pressure estimation or measurement techniques would be required for any future use in LVAD patients.
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Affiliation(s)
- Louis S Fixsen
- Cardiovascular Biomechanics group, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Niels J Petterson
- Cardiovascular Biomechanics group, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Patrick Houthuizen
- Department of Cardiology, Catharina Hospital, Eindhoven, The Netherlands
| | - Marcel C M Rutten
- Cardiovascular Biomechanics group, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Frans N van de Vosse
- Cardiovascular Biomechanics group, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Richard G P Lopata
- Cardiovascular Biomechanics group, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
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8
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See Hoe LE, Bartnikowski N, Wells MA, Suen JY, Fraser JF. Hurdles to Cardioprotection in the Critically Ill. Int J Mol Sci 2019; 20:E3823. [PMID: 31387264 PMCID: PMC6695809 DOI: 10.3390/ijms20153823] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 07/26/2019] [Accepted: 08/03/2019] [Indexed: 02/07/2023] Open
Abstract
Cardiovascular disease is the largest contributor to worldwide mortality, and the deleterious impact of heart failure (HF) is projected to grow exponentially in the future. As heart transplantation (HTx) is the only effective treatment for end-stage HF, development of mechanical circulatory support (MCS) technology has unveiled additional therapeutic options for refractory cardiac disease. Unfortunately, despite both MCS and HTx being quintessential treatments for significant cardiac impairment, associated morbidity and mortality remain high. MCS technology continues to evolve, but is associated with numerous disturbances to cardiac function (e.g., oxidative damage, arrhythmias). Following MCS intervention, HTx is frequently the destination option for survival of critically ill cardiac patients. While effective, donor hearts are scarce, thus limiting HTx to few qualifying patients, and HTx remains correlated with substantial post-HTx complications. While MCS and HTx are vital to survival of critically ill cardiac patients, cardioprotective strategies to improve outcomes from these treatments are highly desirable. Accordingly, this review summarizes the current status of MCS and HTx in the clinic, and the associated cardiac complications inherent to these treatments. Furthermore, we detail current research being undertaken to improve cardiac outcomes following MCS/HTx, and important considerations for reducing the significant morbidity and mortality associated with these necessary treatment strategies.
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Affiliation(s)
- Louise E See Hoe
- Critical Care Research Group, The Prince Charles Hospital, Chermside 4032, Australia.
- Faculty of Medicine, University of Queensland, Chermside 4032, Australia.
| | - Nicole Bartnikowski
- Critical Care Research Group, The Prince Charles Hospital, Chermside 4032, Australia
- Science and Engineering Faculty, Queensland University of Technology, Chermside 4032, Australia
| | - Matthew A Wells
- Critical Care Research Group, The Prince Charles Hospital, Chermside 4032, Australia
- School of Medical Science, Griffith University, Southport 4222, Australia
| | - Jacky Y Suen
- Critical Care Research Group, The Prince Charles Hospital, Chermside 4032, Australia
- Faculty of Medicine, University of Queensland, Chermside 4032, Australia
| | - John F Fraser
- Critical Care Research Group, The Prince Charles Hospital, Chermside 4032, Australia
- Faculty of Medicine, University of Queensland, Chermside 4032, Australia
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9
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A centralized multi-objective model predictive control for a biventricular assist device: An in silico evaluation. Biomed Signal Process Control 2019. [DOI: 10.1016/j.bspc.2018.10.021] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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10
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Dual SA, Zimmermann JM, Neuenschwander J, Cohrs NH, Solowjowa N, Stark WJ, Meboldt M, Schmid Daners M. Ultrasonic sensor concept to fit a ventricular assist device cannula evaluated using geometrically accurate heart phantoms. Artif Organs 2018; 43:467-477. [PMID: 30357874 DOI: 10.1111/aor.13379] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 10/05/2018] [Accepted: 10/18/2018] [Indexed: 12/12/2022]
Abstract
Future left ventricular assist devices (LVADs) are expected to respond to the physiologic need of patients; however, they still lack reliable pressure or volume sensors for feedback control. In the clinic, echocardiography systems are routinely used to measure left ventricular (LV) volume. Until now, echocardiography in this form was never integrated in LVADs due to its computational complexity. The aim of this study was to demonstrate the applicability of a simplified ultrasonic sensor to fit an LVAD cannula and to show the achievable accuracy in vitro. Our approach requires only two ultrasonic transducers because we estimated the LV volume with the LV end-diastolic diameter commonly used in clinical assessments. In order to optimize the accuracy, we assessed the optimal design parameters considering over 50 orientations of the two ultrasonic transducers. A test bench was equipped with five talcum-infused silicone heart phantoms, in which the intra-ventricular surface replicated papillary muscles and trabeculae carnae. The end-diastolic LV filling volumes of the five heart phantoms ranged from 180 to 480 mL. This reference volume was altered by ±40 mL with a syringe pump. Based on the calibrated measurements acquired by the two ultrasonic transducers, the LV volume was estimated well. However, the accuracies obtained are strongly dependent on the choice of the design parameters. Orientations toward the septum perform better, as they interfere less with the papillary muscles. The optimized design is valid for all hearts. Considering this, the Bland-Altman analysis reports the LV volume accuracy as a bias of ±10% and limits of agreement of 0%-40% in all but the smallest heart. The simplicity of traditional echocardiography systems was reduced by two orders of magnitude in technical complexity, while achieving a comparable accuracy to 2D echocardiography requiring a calibration of absolute volume only. Hence, our approach exploits the established benefits of echocardiography and makes them applicable as an LV volume sensor for LVADs.
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Affiliation(s)
- Seraina Anne Dual
- Product Development Group Zurich, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland
| | - Jan Michael Zimmermann
- Product Development Group Zurich, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland
| | - Jürg Neuenschwander
- Swiss Federal Laboratories for Materials Science and Technology, Empa, Dübendorf, Switzerland
| | - Nicholas Heinrich Cohrs
- Functional Materials Laboratory, Institute for Chemical and Bioengineering, ETH Zurich, Zurich, Switzerland
| | - Natalia Solowjowa
- Department of Cardiothoracic and Vascular Surgery, German Heart Center Berlin, Berlin, Germany
| | - Wendelin Jan Stark
- Functional Materials Laboratory, Institute for Chemical and Bioengineering, ETH Zurich, Zurich, Switzerland
| | - Mirko Meboldt
- Product Development Group Zurich, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland
| | - Marianne Schmid Daners
- Product Development Group Zurich, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland
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11
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Johnson CA, Woolley JR, Snyder TA, Shankarraman V, Haney EI, Wagner WR. Assessment of Thrombelastography and Platelet Life Span in Ovines. Artif Organs 2018; 42:E427-E434. [PMID: 30252945 PMCID: PMC6309471 DOI: 10.1111/aor.13282] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2018] [Accepted: 04/01/2018] [Indexed: 12/19/2022]
Abstract
Ovines are a common animal model for the study of cardiovascular devices, where consideration of blood biocompatibility is an essential design criterion. In the ovine model, tools to assess blood biocompatibility are limited and continued investigation to identify and apply additional assays is merited. Toward this end, the thrombelastograph, clinically utilized to assess hemostasis, was used to characterize normal ovine parameters. In addition, platelet labeling with biotin was evaluated for its potential applicability to quantify ovine platelet life span. Mean ovine thrombelastograph values were reaction-time: 4.9 min, K-time: 2 min, angle: 64.1°, maximum amplitude: 68.6mm, actual clot strength: 11.9 kd/s, and coagulation index: 1.5. Reaction time was significantly shorter and maximum amplitude, actual clot strength, and coagulation index were all significantly higher when compared to normal human thrombelastograph values suggesting some hypercoagulability of sheep blood. Biotinylation and reinfusion of ovine platelets allowed temporal tracking of the labeled platelet cohort with flow cytometry. These data indicated a mean ovine platelet life span of 188h with a half-life of 84h. The collection of these parameters for normal ovines demonstrates the applicability of these techniques for subsequent studies where cardiovascular devices may be evaluated and provides an indication of normal ovine values for comparison purposes.
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Affiliation(s)
- Carl A. Johnson
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA
| | - Joshua R. Woolley
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA
| | | | - Venkat Shankarraman
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA
| | | | - William R. Wagner
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA
- Department of Surgery, University of Pittsburgh, Pittsburgh, PA
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12
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A Versatile Hybrid Mock Circulation for Hydraulic Investigations of Active and Passive Cardiovascular Implants. ASAIO J 2018; 65:495-502. [PMID: 30045051 PMCID: PMC6615934 DOI: 10.1097/mat.0000000000000851] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Supplemental Digital Content is available in the text. During the development process of active or passive cardiovascular implants, such as ventricular assist devices or vascular grafts, extensive in-vitro testing is required. The aim of the study was to develop a versatile hybrid mock circulation (HMC) which can support the development of such implants that have a complex interaction with the circulation. The HMC operates based on the hardware-in-the-loop concept with a hydraulic interface of four pressure-controlled reservoirs allowing the interaction of the implant with a numerical model of the cardiovascular system. Three different conditions were investigated to highlight the versatility and the efficacy of the HMC during the development of such implants: 1) biventricular assist device (BiVAD) support with progressive aortic valve insufficiency, 2) total artificial heart (TAH) support with increasing pulmonary vascular resistance, and 3) flow distribution in a total cavopulmonary connection (TCPC) in a Fontan circulation during exercise. Realistic pathophysiologic waveforms were generated with the HMC and all hemodynamic conditions were simulated just by adapting the software. The results of the experiments indicated the potential of physiologic control during BiVAD or TAH support to prevent suction or congestion events, which may occur during constant-speed operation. The TCPC geometry influenced the flow distribution between the right and the left pulmonary artery, which was 10% higher in the latter and led to higher pressures. Together with rapid prototyping methods, the HMC may enhance the design of implants to achieve better hemodynamics. Validation of the models with clinical recordings is suggested for increasing the reliability of the HMC.
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13
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Petrou A, Lee J, Dual S, Ochsner G, Meboldt M, Schmid Daners M. Standardized Comparison of Selected Physiological Controllers for Rotary Blood Pumps: In Vitro Study. Artif Organs 2017; 42:E29-E42. [DOI: 10.1111/aor.12999] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 05/19/2017] [Accepted: 06/29/2017] [Indexed: 11/30/2022]
Affiliation(s)
- Anastasios Petrou
- Department of Mechanical and Process Engineering, Product Development Group Zurich; ETH Zurich; Zurich, Switzerland
| | - Jongseok Lee
- Department of Mechanical and Process Engineering, Product Development Group Zurich; ETH Zurich; Zurich, Switzerland
| | - Seraina Dual
- Department of Mechanical and Process Engineering, Product Development Group Zurich; ETH Zurich; Zurich, Switzerland
| | - Gregor Ochsner
- Department of Mechanical and Process Engineering, Product Development Group Zurich; ETH Zurich; Zurich, Switzerland
| | - Mirko Meboldt
- Department of Mechanical and Process Engineering, Product Development Group Zurich; ETH Zurich; Zurich, Switzerland
| | - Marianne Schmid Daners
- Department of Mechanical and Process Engineering, Product Development Group Zurich; ETH Zurich; Zurich, Switzerland
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Csepe TA, Kilic A. Advancements in mechanical circulatory support for patients in acute and chronic heart failure. J Thorac Dis 2017; 9:4070-4083. [PMID: 29268418 DOI: 10.21037/jtd.2017.09.89] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Cardiogenic shock (CS) continues to have high mortality and morbidity despite advances in pharmacological, mechanical, and reperfusion approaches to treatment. When CS is refractory to medical therapy, percutaneous mechanical circulatory support (MCS) should be considered. Acute MCS devices, ranging from intra-aortic balloon pumps (IABPs) to percutaneous temporary ventricular assist devices (VAD) to extracorporeal membrane oxygenation (ECMO), can aid, restore, or maintain appropriate tissue perfusion before the development of irreversible end-organ damage. Technology has improved patient survival to recovery from CS, but in patients whom cardiac recovery does not occur, acute MCS can be effectively utilized as a bridge to long-term MCS devices and/or heart transplantation. Heart transplantation has been limited by donor heart availability, leading to a greater role of left ventricular assist device (LVAD) support. In patients with biventricular failure that are ineligible for LVAD implantation, further advancements in the total artificial heart (TAH) may allow for improved survival compared to medical therapy alone. In this review, we discuss the current state of acute and durable MCS, ongoing advances in LVADs and TAH devices, improved methods of durable MCS implantation and patient selection, and future MCS developments in this dynamic field that may allow for optimization of HF treatment.
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Affiliation(s)
- Thomas A Csepe
- Division of Cardiac Surgery, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Ahmet Kilic
- Division of Cardiac Surgery, The Ohio State University Wexner Medical Center, Columbus, OH, USA
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15
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Sensor-Based Physiologic Control Strategy for Biventricular Support with Rotary Blood Pumps. ASAIO J 2017; 64:338-350. [PMID: 28938308 DOI: 10.1097/mat.0000000000000671] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Rotary biventricular assist devices (BiVAD) are becoming a clinically accepted treatment option for end-stage biventricular failure. To improve BiVAD efficacy and safety, we propose a control algorithm to achieve the clinical objectives of maintaining left-right-sided balance, restoring physiologic flows, and preventing ventricular suction. The control algorithm consists of two proportional-integral (PI) controllers for left and right ventricular assist devices (LVAD and RVAD) to maintain differential pump pressure across LVAD (ΔPL) and RVAD (ΔPR) to provide left-right balance and physiologic flow. To prevent ventricular suction, LVAD and RVAD pump speed differentials (ΔRPML, ΔRPMR) were maintained above user-defined thresholds. Efficacy and robustness of the proposed algorithm were tested in silico for axial and centrifugal flow BiVAD using 1) normal and excessive ΔPL and/or ΔPR setpoints, 2) rapid threefold increase in pulmonary vascular or vena caval resistances, 3) transient responses from exercise to rest, and 4) ventricular fibrillation. The study successfully demonstrated that the proposed BiVAD algorithm achieved the clinical objectives but required pressure sensors to continuously measure ΔPL and ΔPR. The proposed control algorithm is device independent, should not require any modifications to the pump or inflow/outflow cannulae/grafts, and may be directly applied to current rotary blood pumps for biventricular support.
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In Vivo Evaluation of Physiologic Control Algorithms for Left Ventricular Assist Devices Based on Left Ventricular Volume or Pressure. ASAIO J 2017; 63:568-577. [DOI: 10.1097/mat.0000000000000533] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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17
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Pauls JP, Nandakumar D, Horobin J, Prendeville JD, Simmonds MJ, Fraser JF, Tansley G, Gregory SD. The Effect of Compliant Inflow Cannulae on the Hemocompatibility of Rotary Blood Pump Circuits in an In Vitro Model. Artif Organs 2017. [PMID: 28621838 DOI: 10.1111/aor.12919] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Rotary blood pumps (RBPs) are used for mechanical circulatory support in heart failure patients but exhibit a reduced response to preload changes, which can lead to ventricular suction events. A passive control system, in the form of a compliant inflow cannula (IC), has been developed to mitigate suction, although this device may cause significant hemolysis. This study compared the incidence of mechanically induced hemolysis of two compliant IC designs (strutted and nonstrutted) with a rigid IC (control) in a blood circulation loop over 90 min. The nonstrutted compliant IC introduced high frequency and high amplitude oscillations in RBP inlet pressure and RBP IC resistance. These oscillations were correlated with a significant increase in plasma-free hemoglobin (pfHb) and hemolysis: pfHb increased to 2.005 ± 0.665 g/L, while normalized index of hemolysis (NIH) and modified index of hemolysis (MIH) increased to 0.04945 ± 0.01276 g/100 L and 4.0505 ± 0.6589 after 90 min (P < 0.05). In contrast, the strutted compliant IC performed similar to the clinically utilized rigid IC and did not increase pfHb (0.300 ± 0.090 and 0.320 ± 0.171 g/L, respectively) and rate of hemolysis (NIH 0.00435 ± 0.00155 and 0.00543 ± 0.00371 g/100 L; MIH 0.3896 ± 0.1749 and 0.4261 ± 0.2792, respectively) within the RBP circuit. These data indicated that strutted, compliant ICs meet the hemocompatibility of clinically used rigid ICs while also offering a potential solution to prevent ventricular suction events.
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Affiliation(s)
- Jo P Pauls
- School of Engineering, Griffith University, Southport, Australia.,Innovative Cardiovascular Engineering and Technology Laboratory, Critical Care Research Group, The Prince Charles Hospital, Brisbane, Australia
| | - Deepika Nandakumar
- School of Engineering, Griffith University, Southport, Australia.,Innovative Cardiovascular Engineering and Technology Laboratory, Critical Care Research Group, The Prince Charles Hospital, Brisbane, Australia
| | - Jarod Horobin
- Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia
| | - Justin D Prendeville
- Innovative Cardiovascular Engineering and Technology Laboratory, Critical Care Research Group, The Prince Charles Hospital, Brisbane, Australia.,Science and Engineering Faculty, Queensland University of Technology, Brisbane, Australia
| | - Michael J Simmonds
- Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia
| | - John F Fraser
- Innovative Cardiovascular Engineering and Technology Laboratory, Critical Care Research Group, The Prince Charles Hospital, Brisbane, Australia.,Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia.,School of Medicine, University of Queensland, Brisbane, Queensland, Australia
| | - Geoff Tansley
- School of Engineering, Griffith University, Southport, Australia.,Innovative Cardiovascular Engineering and Technology Laboratory, Critical Care Research Group, The Prince Charles Hospital, Brisbane, Australia
| | - Shaun D Gregory
- School of Engineering, Griffith University, Southport, Australia.,Innovative Cardiovascular Engineering and Technology Laboratory, Critical Care Research Group, The Prince Charles Hospital, Brisbane, Australia.,School of Medicine, University of Queensland, Brisbane, Queensland, Australia
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Left Ventricular Assist Devices: Challenges Toward Sustaining Long-Term Patient Care. Ann Biomed Eng 2017; 45:1836-1851. [DOI: 10.1007/s10439-017-1858-9] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Accepted: 05/22/2017] [Indexed: 11/25/2022]
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Abstract
In this Editor's Review, articles published in 2016 are organized by category and briefly summarized. We aim to provide a brief reflection of the currently available worldwide knowledge that is intended to advance and better human life while providing insight for continued application of technologies and methods of organ Replacement, Recovery, and Regeneration. As the official journal of The International Federation for Artificial Organs, The International Faculty for Artificial Organs, the International Society for Mechanical Circulatory Support, the International Society for Pediatric Mechanical Cardiopulmonary Support, and the Vienna International Workshop on Functional Electrical Stimulation, Artificial Organs continues in the original mission of its founders "to foster communications in the field of artificial organs on an international level." Artificial Organs continues to publish developments and clinical applications of artificial organ technologies in this broad and expanding field of organ Replacement, Recovery, and Regeneration from all over the world. We were pleased to publish our second Virtual Issue in April 2016 on "Tissue Engineering in Bone" by Professor Tsuyoshi Takato. Our first was published in 2011 titled "Intra-Aortic Balloon Pumping" by Dr. Ashraf Khir. Other peer-reviewed Special Issues this year included contributions from the 11th International Conference on Pediatric Mechanical Circulatory Support Systems and Pediatric Cardiopulmonary Perfusion edited by Dr. Akif Ündar and selections from the 23rd Congress of the International Society for Rotary Blood Pumps edited by Dr. Bojan Biocina. We take this time also to express our gratitude to our authors for offering their work to this journal. We offer our very special thanks to our reviewers who give so generously of time and expertise to review, critique, and especially provide meaningful suggestions to the author's work whether eventually accepted or rejected. Without these excellent and dedicated reviewers the quality expected from such a journal could not be possible. We also express our special thanks to our Publisher, John Wiley & Sons for their expert attention and support in the production and marketing of Artificial Organs. We look forward to reporting further advances in the coming years.
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