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Şişli E, Yıldırım C, Aka İB, Tuncer ON, Atay Y, Özbaran M, Pekkan K. Switching the Left and the Right Hearts: A Novel Bi-ventricle Mechanical Support Strategy with Spared Native Single-Ventricle. Ann Biomed Eng 2023; 51:2853-2872. [PMID: 37635154 DOI: 10.1007/s10439-023-03348-1] [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: 01/30/2023] [Accepted: 08/09/2023] [Indexed: 08/29/2023]
Abstract
End-stage Fontan patients with single-ventricle (SV) circulation are often bridged-to-heart transplantation via mechanical circulatory support (MCS). Donor shortage and complexity of the SV physiology demand innovative MCS. In this paper, an out-of-the-box circulation concept, in which the left and right ventricles are switched with each other is introduced as a novel bi-ventricle MCS configuration for the "failing" Fontan patients. In the proposed configuration, the systemic circulation is maintained through a conventional mechanical ventricle assist device (VAD) while the venous circulation is delegated to the native SV. This approach spares the SV and puts it to a new use at the right-side providing the most-needed venous flow pulsatility to the failed Fontan circulation. To analyze its feasibility and performance, eight SV failure modes have been studied via an established multi-compartmental lumped parameter cardiovascular model (LPM). Here the LPM model is experimentally validated against the corresponding pulsatile mock-up flow loop measurements of a representative 15-year-old Fontan patient employing a clinically-approved VAD (Medtronic-HeartWare). The proposed surgical configuration maintained the healthy cardiac index (3-3.5 l/min/m2) and the normal mean systemic arterial pressure levels. For a failed SV with low ejection fraction (EF = 26%), representing a typical systemic Fontan failure, the proposed configuration enabled a ~ 28 mmHg amplitude in the venous/pulmonary waveforms and a 2 mmHg decrease in the central venous pressure (CVP) together with acceptable mean pulmonary artery pressures (17.5 mmHg). The pulmonary vascular resistance (PVR)-SV failure case provided a ~ 5 mmHg drop in the CVP, with venous/pulmonary pulsatility reaching to ~ 22 mmHg. For the high PVR failure case with a healthy SV (EF = 44%) pulmonary hypertension is likely to occur as expected. While this condition is routinely encountered during the heart transplantation and managed through pulmonary vasodilators a need for precise functional assessment of the spared failed-ventricle is recommended if utilized in the PVR failure mode. Comprehensive in vitro and in silico results encourage this novel concept as a low-cost, more physiological alternative to the conventional bi-ventricle MCS pending animal experiments.
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Affiliation(s)
- Emrah Şişli
- Pediatric Cardiovascular Surgery, Department of Cardiovascular Surgery, Osmangazi University Faculty of Medicine, Büyükdere District, Campus of Meşelik, Tepebaşı, 26480, Eskisehir, Turkey.
| | - Canberk Yıldırım
- Department of Biomedical Sciences and Engineering, Koç University, Istanbul, Turkey
| | - İbrahim Başar Aka
- Department of Mechatronics Engineering, İstanbul Bilgi University, Istanbul, Turkey
| | - Osman Nuri Tuncer
- Pediatric Cardiovascular Surgery, Department of Cardiovascular Surgery, Ege University Faculty of Medicine, Izmir, Turkey
| | - Yüksel Atay
- Pediatric Cardiovascular Surgery, Department of Cardiovascular Surgery, Ege University Faculty of Medicine, Izmir, Turkey
| | - Mustafa Özbaran
- Heart Transplantation, Department of Cardiovascular Surgery, Ege University Faculty of Medicine, Izmir, Turkey
| | - Kerem Pekkan
- Department of Mechanical Engineering, Koç University, Rumeli Feneri Campus, Sarıyer, Istanbul, Turkey.
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Mehmood K, Arshad M, Lazoglu I, Küçükaksu DS, Bakuy V. In-silico hemodynamic ramp testing of ventricular assist device implanted patients using acausal cardiovascular-VAD modeling. Artif Organs 2023; 47:1452-1463. [PMID: 37306082 DOI: 10.1111/aor.14597] [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: 04/06/2023] [Revised: 05/15/2023] [Accepted: 06/08/2023] [Indexed: 06/13/2023]
Abstract
BACKGROUND While cardiovascular system and mechanical circulatory support devices are efficiently model the effect of disease and assistance, they can also lend valuable insights into clinical procedures. This study demonstrates the use of a CVS-VAD model for an invasive procedure; hemodynamic ramp testing, in-silico. METHODS The CVS model is developed using validated models in literature, using Simscape™. An analytically derived pump model is calibrated for the HeartWare VAD. Dilated cardiomyopathy is used as an illustrative example of heart failure, and heart failure patients are created virtually by calibrating the model with requisite disease parameters obtained from published patient data. A clinically applied ramp study protocol is adopted whereby speed optimization is performed following clinically accepted hemodynamic normalization criteria. Trends in hemodynamic variables in response to pump speed increments are obtained. Optimal speed ranges are obtained for the three virtual patients based on target values of central venous pressure (CVP), pulmonary capillary wedge pressure (PCWP), cardiac output (CO), and mean arterial pressure (MAP) for hemodynamic stabilization. RESULTS Appreciable speed changes in the mild case (300 rpm), slight changes in the moderate case (100 rpm), and no changes in the simulated severe case are possible. CONCLUSION The study demonstrates a novel application of cardiovascular modeling using an open-source acausal model, which can be potentially beneficial for medical education and research.
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Affiliation(s)
- Khunsha Mehmood
- Department of Mechanical Engineering, Koç University, Istanbul, Turkey
| | - Munam Arshad
- Department of Mechanical Engineering, Koç University, Istanbul, Turkey
| | - Ismail Lazoglu
- Department of Mechanical Engineering, Koç University, Istanbul, Turkey
| | - Deniz Süha Küçükaksu
- Department of Cardiovascular Surgery, Başkent University Istanbul Health Application and Research Center, Istanbul, Turkey
| | - Vedat Bakuy
- Department of Cardiovascular Surgery, Başkent University Istanbul Health Application and Research Center, Istanbul, Turkey
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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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Meissner F, Eichelkraut D, Schimmel M, Maier S, Vestner H, Schoen M, Czerny M, Bothe W. Impact of an Accessory for Left Ventricular Assist Devices on Device Flow and Pressure Head In Vitro. Bioengineering (Basel) 2023; 10:bioengineering10040486. [PMID: 37106673 PMCID: PMC10135582 DOI: 10.3390/bioengineering10040486] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Revised: 04/14/2023] [Accepted: 04/17/2023] [Indexed: 04/29/2023] Open
Abstract
A novel accessory directing the blood from the outflow of a left ventricular assist device (LVAD) back through the left ventricular apex and across the aortic valve allows LVAD implantation via the left ventricular apex solely but may affect the LVAD performance. We quantified the effect of the accessory on LVAD flow and pressure head in vitro. In a mock circulatory loop, a centrifugal-flow LVAD (HeartMate 3, Abbott, Abbott Park, IL, USA) with (Accessory) and without the accessory (Control) was compared under physiological conditions using a water/glycerol solution as a blood substitute. The pump was operated at 4000, 5200, and 6400 rpm and 5 different resistance levels. Flow, inlet, and outlet pressure were measured, and pressure head was calculated. Compared to the Control, flow and pressure head in the Accessory group were reduced by an overall average of 0.26 L/min and 9.9 mmHg (all speeds and resistance levels). The highest decline in flow and pressure head occurred at the lowest resistance levels. In conclusion, the accessory leads to a reduction of LVAD flow and pressure head that is enhanced by decreases in resistance. Future developments in the LVAD accessory's design may reduce these effects and allow unimpaired LVAD performance and minimally invasive device implantation.
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Affiliation(s)
- Florian Meissner
- Department of Cardiovascular Surgery, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Hugstetter Str. 55, 79106 Freiburg, Germany
| | - Derya Eichelkraut
- Department of Cardiovascular Surgery, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Hugstetter Str. 55, 79106 Freiburg, Germany
| | - Marius Schimmel
- Department of Cardiovascular Surgery, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Hugstetter Str. 55, 79106 Freiburg, Germany
| | - Sven Maier
- Department of Cardiovascular Surgery, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Hugstetter Str. 55, 79106 Freiburg, Germany
| | - Heiko Vestner
- Department of Cardiovascular Surgery, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Hugstetter Str. 55, 79106 Freiburg, Germany
| | - Manuela Schoen
- Department of Cardiovascular Surgery, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Hugstetter Str. 55, 79106 Freiburg, Germany
| | - Martin Czerny
- Department of Cardiovascular Surgery, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Hugstetter Str. 55, 79106 Freiburg, Germany
| | - Wolfgang Bothe
- Department of Cardiovascular Surgery, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Hugstetter Str. 55, 79106 Freiburg, Germany
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A Mathematical Model of Artificial Pulse Synchronization for the HeartMate3 Left Ventricular Assist Device. ASAIO J 2023; 69:284-289. [PMID: 35797437 DOI: 10.1097/mat.0000000000001771] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Constant speed control of rotary LVADs attenuates vascular pulsatility, which has been linked to clinical complications such as thrombus formation, bleeding, and valvular dysfunction. Speed modulation can improve pulsatility and washout, but optimization requires coordination with the native heartbeat. A simple mathematical model of the left ventricle-left ventricular assist device (LV-LVAD) flow interaction was developed that sums the individual contributions of the native LV and the HeartMate3 artificial pulse (AP) to predict the total systemic flow. The model flow and pulsatility predictions results were in good agreement with experimental data from a mock circulatory loop measured for full bypass support conditions. The model was used to evaluate three schemes for optimizing the synchronization of the AP with the native heart. The optimized interaction occurred when the AP speed increase occurred during contraction, resulting in a doubling of flow pulsatility, and corresponded to an increase in the area enclosed by the dynamic pressure-flow relation. The model provides a simple tool for exploring the optimization of LVAD speed modulation that can reduce the time and expense of mock loop studies during the development process.
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Gil A, Navarro R, Quintero P, Mares A. Hemocompatibility and hemodynamic comparison of two centrifugal LVADs: HVAD and HeartMate3. Biomech Model Mechanobiol 2023; 22:871-883. [PMID: 36648697 PMCID: PMC10167126 DOI: 10.1007/s10237-022-01686-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Accepted: 12/28/2022] [Indexed: 01/18/2023]
Abstract
Mechanical circulatory support using ventricular assist devices is a common technique for treating patients suffering from advanced heart failure. The latest generation of devices is characterized by centrifugal turbopumps which employ magnetic levitation bearings to ensure a gap clearance between moving and static parts. Despite the increasing use of these devices as a destination therapy, several long-term complications still exist regarding their hemocompatibility. The blood damage associated with different pump designs has been investigated profoundly in the literature, while the hemodynamic performance has been hardly considered. This work presents a novel comparison between the two main devices of the latest generation-HVAD and HM3-from both perspectives, hemodynamic performance and blood damage. Computational fluid dynamics simulations are performed to model the considered LVADs, and computational results are compared to experimental measurements of pressure head to validate the model. Enhanced performance and hemocompatibility are detected for HM3 owing to its design incorporating more conventional blades and larger gap clearances.
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Affiliation(s)
- Antonio Gil
- CMT-Motores Térmicos, Universitat Politècnica de València, Camino de Vera, S/N, 46022, Valencia, Spain
| | - Roberto Navarro
- CMT-Motores Térmicos, Universitat Politècnica de València, Camino de Vera, S/N, 46022, Valencia, Spain
| | - Pedro Quintero
- CMT-Motores Térmicos, Universitat Politècnica de València, Camino de Vera, S/N, 46022, Valencia, Spain
| | - Andrea Mares
- CMT-Motores Térmicos, Universitat Politècnica de València, Camino de Vera, S/N, 46022, Valencia, Spain.
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Girfoglio M, Ballarin F, Infantino G, Nicoló F, Montalto A, Rozza G, Scrofani R, Comisso M, Musumeci F. Non-intrusive PODI-ROM for patient-specific aortic blood flow in presence of a LVAD device. Med Eng Phys 2022; 107:103849. [DOI: 10.1016/j.medengphy.2022.103849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Revised: 06/23/2022] [Accepted: 07/10/2022] [Indexed: 10/17/2022]
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(Physiology of Continuous-flow Left Ventricular Assist Device Therapy. Translation of the document prepared by the Czech Society of Cardiology). COR ET VASA 2022. [DOI: 10.33678/cor.2022.040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Rosenbaum AN, Antaki JF, Behfar A, Villavicencio MA, Stulak J, Kushwaha SS. Physiology of Continuous-Flow Left Ventricular Assist Device Therapy. Compr Physiol 2021; 12:2731-2767. [PMID: 34964115 DOI: 10.1002/cphy.c210016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The expanding use of continuous-flow left ventricular assist devices (CF-LVADs) for end-stage heart failure warrants familiarity with the physiologic interaction of the device with the native circulation. Contemporary devices utilize predominantly centrifugal flow and, to a lesser extent, axial flow rotors that vary with respect to their intrinsic flow characteristics. Flow can be manipulated with adjustments to preload and afterload as in the native heart, and ascertainment of the predicted effects is provided by differential pressure-flow (H-Q) curves or loops. Valvular heart disease, especially aortic regurgitation, may significantly affect adequacy of mechanical support. In contrast, atrioventricular and ventriculoventricular timing is of less certain significance. Although beneficial effects of device therapy are typically seen due to enhanced distal perfusion, unloading of the left ventricle and atrium, and amelioration of secondary pulmonary hypertension, negative effects of CF-LVAD therapy on right ventricular filling and function, through right-sided loading and septal interaction, can make optimization challenging. Additionally, a lack of pulsatile energy provided by CF-LVAD therapy has physiologic consequences for end-organ function and may be responsible for a series of adverse effects. Rheological effects of intravascular pumps, especially shear stress exposure, result in platelet activation and hemolysis, which may result in both thrombotic and hemorrhagic consequences. Development of novel solutions for untoward device-circulatory interactions will facilitate hemodynamic support while mitigating adverse events. © 2021 American Physiological Society. Compr Physiol 12:1-37, 2021.
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Affiliation(s)
- Andrew N Rosenbaum
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota, USA.,William J von Liebig Center for Transplantation and Clinical Regeneration, Mayo Clinic, Rochester, Minnesota, USA
| | - James F Antaki
- Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York, USA
| | - Atta Behfar
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota, USA.,William J von Liebig Center for Transplantation and Clinical Regeneration, Mayo Clinic, Rochester, Minnesota, USA.,VanCleve Cardiac Regenerative Medicine Program, Center for Regenerative Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | | | - John Stulak
- Department of Cardiovascular Surgery, Mayo Clinic, Rochester, Minnesota, USA
| | - Sudhir S Kushwaha
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota, USA.,William J von Liebig Center for Transplantation and Clinical Regeneration, Mayo Clinic, Rochester, Minnesota, USA
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10
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May-Newman K. Dynamic pressure-flow curve analysis of the native heart and left ventricular assist device for full and partial bypass conditions. Artif Organs 2021; 46:1077-1085. [PMID: 34932239 DOI: 10.1111/aor.14157] [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: 07/10/2021] [Revised: 10/14/2021] [Accepted: 11/18/2021] [Indexed: 12/01/2022]
Abstract
BACKGROUND During left ventricular assist device (LVAD) support, the external work performed by the native heart combines with the work performed by the rotary LVAD to provide cyclic flow through the LVAD and, in some conditions, through the aortic valve. In this study, a balance of external work was developed and validated for both full and partial bypass conditions that includes valve opening and aortic compliance. METHODS The theory assumes a steady-state contribution of external work from the rotary LVAD and a dynamic portion from the heart. Cyclic flow may be ejected through either the LVAD or ascending aorta, and an energy absorption term accounts for aortic compliance. Mock loop studies were performed for LV ejection fractions of 10%-28% combined with HeartMate II LVAD support at 8 and 11 krpm to produce a range of full and partial bypass conditions. The external work of the LVAD and native heart was computed from the experimental pressure-flow (H-Q) relations and compared to the theory. RESULTS Native heart contraction produces a counterclockwise loop in the pressure-flow relation of the LVAD which increased with ejection fraction, and during full bypass conditions the external work was preserved in the total systemic flow. During partial bypass conditions, forward flow through the ascending aorta was accompanied by a reversal during aortic valve closure resulting in a reduction in energy in the downstream flow. CONCLUSIONS The study presents a balance of external work during full and partial bypass LVAD support. Experimental data validated the additional terms corresponding to forward flow and aortic compliance that contribute to the system balance. This expanded theory can be applied to LVAD design and control to improve pulsatility and aortic valve biomechanics.
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Affiliation(s)
- Karen May-Newman
- Bioengineering Program, San Diego State University, San Diego, California, USA
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11
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Tang PC, Duggal NM, Haft JW, Romano MA, Bolling SF, El Ela AA, Wu X, Colvin MM, Aaronson KD, Pagani FD. Left Ventricular Assist Device Implantation in Patients with Preoperative Severe Mitral Regurgitation. ASAIO J 2021; 67:1139-1147. [PMID: 34570728 PMCID: PMC11177295 DOI: 10.1097/mat.0000000000001379] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
We examined cardiac features associated with residual mitral regurgitation (MR) following continuous-flow left ventricular assist device (cfLVAD) implant. From 2003 to 2017, 134 patients with severe MR underwent cfVLAD implant without mitral valve (MV) intervention. Echocardiographic (echo) assessment occurred pre-cfLVAD, early post-cfLVAD, and at last available echo. Ventricular and atrial volumes were calculated from established formulas and normalized to be predicted. Cluster analysis based on preoperative normalized left ventricular and atrial volumes, and MV height identified grades 1, 2, and 3 with progressively larger cardiac chamber sizes. Median early echo follow-up was 0.92 (0.55, 1.45) months and the last follow-up was 15.12 (5.28, 38.28) months. Mitral regurgitation improved early after cfLVAD by 2.10 ± 1.16 grades (p < 0.01). Mitral regurgitation severity at the last echocardiogram positively correlated with the preoperative left ventricular volume (p = 0.014, R = 0.212), left atrial volume (p = 0.007, R = 0.233), MV anteroposterior height (p = 0.032, R = 0.185), and MV mediolateral diameter (p = 0.043, R = 0.175). Morphologically, smaller grade 1 hearts were correlated with MR resolution at the late follow-up (p = 0.023). Late right ventricular failure (RVF) at the last clinical follow-up was less in grade 1 (4/48 [8.3%]) compared with grades 2 and 3 (26/86 [30.2%]), p = 0.004). Grade 1 cardiac dimensions correlates with improvement in severe MR and had less late RVF.
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Affiliation(s)
- Paul C. Tang
- Department of Cardiac Surgery, University of Michigan Frankel Cardiovascular Center, Ann Arbor, Michigan
| | - Neal M. Duggal
- Department of Anesthesiology, University of Michigan Frankel Cardiovascular Center, Ann Arbor, Michigan
| | - Jonathan W. Haft
- Department of Cardiac Surgery, University of Michigan Frankel Cardiovascular Center, Ann Arbor, Michigan
| | - Matthew A. Romano
- Department of Cardiac Surgery, University of Michigan Frankel Cardiovascular Center, Ann Arbor, Michigan
| | - Steven F. Bolling
- Department of Cardiac Surgery, University of Michigan Frankel Cardiovascular Center, Ann Arbor, Michigan
| | - Ashraf Abou El Ela
- Department of Cardiac Surgery, University of Michigan Frankel Cardiovascular Center, Ann Arbor, Michigan
| | - Xiaoting Wu
- Department of Cardiac Surgery, University of Michigan Frankel Cardiovascular Center, Ann Arbor, Michigan
| | - Monica M. Colvin
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan Frankel Cardiovascular Center, Ann Arbor, Michigan
| | - Keith D. Aaronson
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan Frankel Cardiovascular Center, Ann Arbor, Michigan
| | - Francis D. Pagani
- Department of Cardiac Surgery, University of Michigan Frankel Cardiovascular Center, Ann Arbor, Michigan
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Yu Z, Tan J, Wang S, Guo B. Multiple parameters and target optimization of splitter blades for axial spiral blade blood pump using computational fluid mechanics, neural networks, and particle image velocimetry experiment. Sci Prog 2021; 104:368504211039363. [PMID: 34463585 PMCID: PMC10461372 DOI: 10.1177/00368504211039363] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The blood pump is an implantable device with strict performance requirements. Any effective structural improvement will help to improve the treatment of patients. However, the research of blood pump structure improvement is a complex optimization problem with multiple parameters and objectives. This study takes the splitter blade as the object of structural improvement. Computational fluid mechanics and neural networks are combined in research and optimization. And hydraulic experiments and micro particle image velocimetry technology were used. In the optimization study, the number of blades, axial length and circumferential offset are optimization parameters, and hydraulic performance and hemolytic prediction index are optimization targets. The study analyzes the influence of each parameter on performance and completes the optimization of the parameters. In the results, the optimal parameters of number of blades, axial length ratio, and circumferential offset are 2.6° and 0.41°, respectively. Under optimized parameters, hydraulic performance can be significantly improved. And the results of hemolysis prediction and micro particle image velocimetry experiments reflect that there is no increase in the risk of hemolytic damage. The results of this study provide a method and ideas for improving the structure of the axial spiral blade blood pump. The established optimization method can be effectively applied to the design and research of axial spiral blade blood pumps with complex, high precision, and multiple parameters and targets.
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Affiliation(s)
- Zheqin Yu
- College of Energy and Power
Engineering, Changsha University of Science and
Technology, China
| | - Jianping Tan
- College of Mechanical and Electrical
Engineering, Central South University, China
| | - Shuai Wang
- College of Mechanical and Electrical
Engineering, Central South University, China
| | - Bin Guo
- College of Mechanical and Electrical
Engineering, Central South University, China
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YAZDANPANH-ARDAKANI KOHYAR, NIROOMAND-OSCUII HANIEH. COMPUTATIONAL STUDY ON THE PERFORMANCE OF A CENTRIFUGAL LVAD WITH THE IMPELLER DESIGNED BY INDUSTRIAL METHOD: PROPOSING SIMPLE-TO-MANUFACTURE LVAD’S IMPELLERS. J MECH MED BIOL 2021. [DOI: 10.1142/s0219519421500111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Although the demand of donor hearts for patients with end-stage heart failure is growing, its supply has remained constant. Ventricular assist devices (VADs) provide a chance of finding donor heart by increasing waiting period. In this study, the main goal is to employ an industrial method (point-by-point method) for designing blades profile with a simplified geometry which can be produced by conventional manufacturing methods. In this study, a centrifugal continuous-flow rotary pump is designed and the effects of components’ different geometries on the left ventricular assist devices (LVADs) function are investigated. Moreover, both hydraulic performance and blood damages (hemolysis index (HI)) caused by the pump are considered as design criteria. ANSYS CFX 17 is used to analyze the performance of the designed LVAD. Additionally, the geometry of components are investigated based on fulfilling the required performance of the LVAD while reducing the blood damage level. Comparing the designed VAD with the commercial ones shows that the designed blade further improves the performance of the centrifugal LVAD. Therefore, designing the impeller’s blade profile with point-by-point method seems to be promising. Simplicity in manufacturing is considered to be a big advantage for a design which also leads to lower manufacturing costs. This study demonstrates how industrial design methods can be employed to design simple-to-manufacture impellers which are suitable for LVADs.
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Left Ventricular Assist Device Flow Pattern Analysis Using a Novel Model Incorporating Left Ventricular Pulsatility. ASAIO J 2021; 67:724-732. [DOI: 10.1097/mat.0000000000001341] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
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Yu Z, Tan J, Wang S. Enhanced discrete phase model for multiphase flow simulation of blood flow with high shear stress. Sci Prog 2021; 104:368504211008064. [PMID: 33788651 PMCID: PMC10358624 DOI: 10.1177/00368504211008064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Shear stress is often present in the blood flow within blood-contacting devices, which is the leading cause of hemolysis. However, the simulation method for blood flow with shear stress is still not perfect, especially the multiphase flow model and experimental verification. In this regard, this study proposes an enhanced discrete phase model for multiphase flow simulation of blood flow with shear stress. This simulation is based on the discrete phase model (DPM). According to the multiphase flow characteristics of blood, a virtual mass force model and a pressure gradient influence model are added to the calculation of cell particle motion. In the experimental verification, nozzle models were designed to simulate the flow with shear stress, varying the degree of shear stress through different nozzle sizes. The microscopic flow was measured by the Particle Image Velocimetry (PIV) experimental method. The comparison of the turbulence models and the verification of the simulation accuracy were carried out based on the experimental results. The result demonstrates that the simulation effect of the SST k-ω model is better than other standard turbulence models. Accuracy analysis proves that the simulation results are accurate and can capture the movement of cell-level particles in the flow with shear stress. The results of the research are conducive to obtaining accurate and comprehensive analysis results in the equipment development phase.
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Affiliation(s)
- Zheqin Yu
- College of Energy and Power Engineering, Changsha University of Science & Technology, Hunan, China
- College of Mechanical and Electrical Engineering, Central South University, Changsha, Hunan, China
| | - Jianping Tan
- College of Mechanical and Electrical Engineering, Central South University, Changsha, Hunan, China
| | - Shuai Wang
- College of Mechanical and Electrical Engineering, Central South University, Changsha, Hunan, China
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Köhne I. Kontinuierlich fördernde Blutpumpen für die Langzeitherzunterstützung. ZEITSCHRIFT FUR HERZ THORAX UND GEFASSCHIRURGIE 2020. [DOI: 10.1007/s00398-020-00398-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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17
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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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Liu GM, Hou JF, Wei RJ, Hu SS. A 3-dimensional-printed left ventricle model incorporated into a mock circulatory loop to investigate hemodynamics inside a severely failing ventricle supported by a blood pump. Artif Organs 2020; 45:143-150. [PMID: 32812671 DOI: 10.1111/aor.13802] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 07/20/2020] [Accepted: 08/10/2020] [Indexed: 11/29/2022]
Abstract
Intraventricular blood stasis is a design consideration for continuous flow blood pumps and might contribute to adverse events such as thrombosis and ventricular suction. However, the blood flow inside left ventricles (LVs) supported by blood pumps is still unclear. In vitro experiments were conducted to imitate how the hydraulic performance of an axial blood pump affects the intraventricular blood flow of a severe heart failure patient, such as velocity distribution, vorticity, and standard deviation of velocity. In this study, a silicone model of the LV was constructed from the computed tomography data of one patient with heart failure and was 3D printed. Then, intraventricular flow was visualized by particle image velocimetry equipment within a mock circulation loop. The results showed that the axial blood pump suctions most of the blood in a severely failing LV, there was an altered flow status within the LV, and blood stasis appeared in the central region of the LV. Some blood may be suctioned from the aortic valve to the blood pump because the patient's native heart was severely failing. Blood stasis at the LV center may cause thrombosis in the LV. The vortex flow near the inner wall of the LV can thoroughly wash the left ventricular cavity.
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Affiliation(s)
- Guang-Mao Liu
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Jian-Feng Hou
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | | | - Sheng-Shou Hu
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
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Yu Z, Tan J, Wang S, Guo B. Structural improvement study of streamline design method, conical hub, and auxiliary blades for axial blood pump. Int J Artif Organs 2020; 44:251-261. [PMID: 32957840 DOI: 10.1177/0391398820959344] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The blood pump is a medical device used to assist or replace the diseased heart. Research on the structure of blood pumps has been committed to achieving better hemolysis and hydraulic performance. The purpose of this study was to find some effective ways to improve design methods and hydraulic structures. The research contents of improvement include: (1) improved blade streamline design method; (2) conical impeller hub; (3) additional auxiliary blades. Characteristic analysis and parameter design were carried out on the above three aspects. The methods used in this study included Dynamics (CFD) simulation, hydraulic experiments, and Particle Image Velocimetry (PIV) experiments. The results showed that this improved streamline design method could improve the distortion of blades and ensure a smaller impeller length. And, in the enhanced design of the hub, it is designed to be conical with inlet and outlet diameters of 7.5 and 12.8 mm, respectively. Furthermore, the auxiliary blades between the main blades are analyzed and designed. The results have the best performance optimization effect when the length of the auxiliary blades is 55% of the main blades. In general, the structural improvements in this study achieved the effect of improving hydraulic performance and avoiding increased hemolysis. These methods can be considered as an effective means of improving blood pump performance.
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Affiliation(s)
- Zheqin Yu
- College of Mechanical and Electrical Engineering, Central South University, Hunan, China
| | - Jianping Tan
- College of Mechanical and Electrical Engineering, Central South University, Hunan, China
| | - Shuai Wang
- College of Mechanical and Electrical Engineering, Central South University, Hunan, China
| | - Bin Guo
- School of Mechanical and Electrical Engineering, Jiangxi University of Science and Technology, Ganzhou, Jiangxi, China
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Zhang J, Chen Z, Griffith BP, Wu ZJ. Computational characterization of flow and blood damage potential of the new maglev CH-VAD pump versus the HVAD and HeartMate II pumps. Int J Artif Organs 2020; 43:653-662. [PMID: 32043405 DOI: 10.1177/0391398820903734] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Left ventricular assist devices are routinely used to treat patients with advanced heart failure as a bridge to transplant or a destination therapy. However, non-physiological shear stress generated by left ventricular assist devices damages blood cells. The continued development of novel left ventricular assist devices is essential to improve the left ventricular assist device therapy for heart failure patients. The CH-VAD is a new maglev centrifugal left ventricular assist device. In this study, the CH-VAD pump was numerically analyzed and compared with the HVAD and HeartMate II pumps under two clinically relevant conditions (flow: 4.5 L/min, pressure head: normal ~80 and hypertension ~120 mmHg). The velocity and shear stress fields, washout, and hemolysis index of the three pumps were assessed with computational fluid dynamics analysis. Under the same condition, the CH-VAD hemolysis index was two times lower than the HVAD and HeartMate II pumps; the CH-VAD had the least percentage volume with shear stress larger than 100 Pa (i.e. normal condition: 0.4% vs HVAD 1.0%, and HeartMate II 2.9%). Under the normal condition, more than 98% was washed out of the three pumps within 0.4 s. The washout times were slightly shorter under the hypertension condition for the three pumps. No regions inside the CH-VAD or HVAD had extremely long residential time, while areas near the straightener of the HeartMate II pump had long residential time (>4 s) indicating elevated risks of thrombosis. The computational fluid dynamics results suggested that the CH-VAD pump has a better hemolytic biocompatibility than the HVAD and HeartMate II pumps under the normal and hypertension conditions.
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Affiliation(s)
- Jiafeng Zhang
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Zengsheng Chen
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Bartley P Griffith
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Zhongjun J Wu
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA.,Fischell Department of Bioengineering, A. James Clark School of Engineering, University of Maryland, College Park, MD, USA
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Advances in Hemodynamic Analysis in Cardiovascular Diseases Investigation of Energetic Characteristics of Adult and Pediatric Sputnik Left Ventricular Assist Devices during Mock Circulation Support. Cardiol Res Pract 2019; 2019:4593174. [PMID: 31885902 PMCID: PMC6925692 DOI: 10.1155/2019/4593174] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 09/11/2019] [Accepted: 10/17/2019] [Indexed: 11/17/2022] Open
Abstract
The need to simulate the operating conditions of the human body is a key factor in every study and engineering process of a bioengineering device developed for implantation. In the present paper, we describe in detail the interaction between the left ventricle (LV) and our Sputnik left ventricular assist devices (LVADs). This research aims to evaluate the influence of different rotary blood pumps (RBPs) on the LV depending on the degree of heart failure (HF), in order to investigate energetic characteristics of the LV-LVAD interaction and to estimate main parameters of left ventricular unloading. We investigate energetic characteristics of adult Sputnik 1 and Sputnik 2 LVADs connected to a hybrid adult mock circulation (HAMC) and also for the Sputnik pediatric rotary blood pump (PRBP) connected to a pediatric mock circulation (PMC). A major improvement of the LV unloading is observed during all simulations for each particular heart failure state when connected to the LVAD, with sequential pump speed increased within 5000–10000 rpm for adult LVADs and 6000–13000 rpm for PRBP with 200 rpm step. Additionally, it was found that depending on the degree of heart failure, LVADs influence the LV in different ways and a significant support level cannot be achieved without the aortic valve closure. Furthermore, this study expands the information on LV-LVAD interaction, which leads to the optimization of the RBP speed rate control in clinics for adult and pediatric patients suffering from heart failure. Finally, we show that the implementation of control algorithms using the modulation of the RBP speed in order to open the aortic valve and unload the LV more efficiently is necessary and will be content of further research.
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22
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Influence of Impeller Speed Patterns on Hemodynamic Characteristics and Hemolysis of the Blood Pump. APPLIED SCIENCES-BASEL 2019. [DOI: 10.3390/app9214689] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
A continuous-flow output mode of a rotary blood pump reduces the fluctuation range of arterial blood pressure and easily causes complications. For a centrifugal rotary blood pump, sinusoidal and pulsatile speed patterns are designed using the impeller speed modulation. This study aimed to analyze the hemodynamic characteristics and hemolysis of different speed patterns of a blood pump in patients with heart failure using computational fluid dynamics (CFD) and the lumped parameter model (LPM). The results showed that the impeller with three speed patterns (including the constant speed pattern) met the normal blood demand of the human body. The pulsating flow generated by the impeller speed modulation effectively increased the maximum pulse pressure (PP) to 12.7 mm Hg, but the hemolysis index (HI) in the sinusoidal and pulsatile speed patterns was higher than that in the constant speed pattern, which was about 2.1 × 10−5. The flow path of the pulsating flow field in the spiral groove of the hydrodynamic suspension bearing was uniform, but the alternating high shear stress (0~157 Pa) was caused by the impeller speed modulation, causing blood damage. Therefore, the rational modulation of the impeller speed and the structural optimization of a blood pump are important for improving hydrodynamic characteristics and hemolysis.
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Berk ZBK, Zhang J, Chen Z, Tran D, Griffith BP, Wu ZJ. Evaluation of in vitro hemolysis and platelet activation of a newly developed maglev LVAD and two clinically used LVADs with human blood. Artif Organs 2019; 43:870-879. [PMID: 31001834 PMCID: PMC6733624 DOI: 10.1111/aor.13471] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 03/08/2019] [Accepted: 04/11/2019] [Indexed: 12/17/2022]
Abstract
In vitro hemolysis testing remains one of the most important performance measures to judge the hemocompatibility of a left ventricular assist device (LVAD). Clinically relevant operating conditions and appropriate testing blood are essential to infer in vitro data for potential clinical use. This in vitro study was carried out to evaluate and compare the hemolytic performance of a newly developed magnetically levitated (maglev) LVAD (CH-VAD) with two clinically used LVADs (HVAD and HeartMate II (HMII)) using fresh human blood. A small volume (~300 mL) in vitro circulating flow loop was constructed with a LVAD generated flow of 4.5 L/min at the nominal or reported clinical operating speed for each LVAD. The blood was circulated in the loop for 4 hours with samples drawn at baseline and hourly. Plasma-free hemoglobin (PFH) concentrations in the hourly blood samples were determined with spectrophotometry. Normalized index of hemolysis (NIH) was calculated to compare the hemolytic performance of the CH-VAD and the two reference LVADs. Platelet activation was measured with flow cytometry. The experimental test for each device was repeated at least 7 times. The data from this study showed that all the three LVADs generated very low hemolysis (NIH <0.01 g/100 L). The CH-VAD was found to have a significantly lower NIH value (0.00135 ± 0.00032 g/100 L) compared to the HVAD (0.00525 ± 0.00183 g/100 L) and the HMII (0.00583 ± 0.00182 g/100 L). No statistically significant difference in device-generated hemolysis was found between the HVAD and the HMII. The level of platelet activation induced by the CH-VAD is significantly lower than those by the HVAD and the HMII. The data suggest that the shear-induced hemolysis and platelet activation of the CH-VAD are acceptable relative to the two LVADs currently in clinical use.
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Affiliation(s)
- Zachary B. K. Berk
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Jiafeng Zhang
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Zengsheng Chen
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Douglas Tran
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Bartley P. Griffith
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Zhongjun J. Wu
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
- Fischell Department of Bioengineering, A. James Clark School of Engineering, University of Maryland, College Park, MD 20742,USA
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Shi Y, Yang H. Mock circulatory test rigs for the in vitro testing of artificial cardiovascular organs. J Med Eng Technol 2019; 43:223-234. [PMID: 31464556 DOI: 10.1080/03091902.2019.1653390] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
In vitro study plays an important role in the experimental study of cardiovascular dynamics. An essential hardware facility that mimics the blood flow changes and provides the required test conditions, a mock circulatory test rig (MCTR), is imperative for the execution of in vitro study. This paper examines the current MCTRs in use for the testing of artificial cardiovascular organs. Various aspects of the MCTRs are surveyed, including the necessity of in vitro study, the building of MCTRs, relevant standards, general system structure (e.g., the motion and driving, fluid, measurement subsystems), classification, motion driving mechanism of MCTRs, and the considerations for the modelling of the physiological impedance of MCTRs. Examples of the steady and pulsatile flow types of the MCTRs are introduced. Recent developments in MCTRs are inspected and possible future design improvements suggested. This study will help researchers in the design, construction, analysis, and selection of MCTRs for cardiovascular research.
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Affiliation(s)
- Yubing Shi
- College of Medical Technology, Shaanxi University of Chinese Medicine , Xianyang , PR China
| | - Hongyi Yang
- College of Medical Technology, Shaanxi University of Chinese Medicine , Xianyang , PR China
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26
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Boes S, Thamsen B, Haas M, Daners MS, Meboldt M, Granegger M. Hydraulic Characterization of Implantable Rotary Blood Pumps. IEEE Trans Biomed Eng 2019; 66:1618-1627. [DOI: 10.1109/tbme.2018.2876840] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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27
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Shi Y, Korakianitis T, Li Z, Shi Y. Structure and motion design of a mock circulatory test rig. J Med Eng Technol 2018; 42:443-452. [PMID: 30499728 DOI: 10.1080/03091902.2018.1543467] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Mock circulatory test rig (MCTR) is the essential and indispensable facility in the cardiovascular in vitro studies. The system configuration and the motion profile of the MCTR design directly influence the validity, precision, and accuracy of the experimental data collected. Previous studies gave the schematic but never describe the structure and motion design details of the MCTRs used, which makes comparison of the experimental data reported by different research groups plausible but not fully convincing. This article presents the detailed structure and motion design of a sophisticated MCTR system, and examines the important issues such as the determination of the ventricular motion waveform, modelling of the physiological impedance, etc., in the MCTR designing. The study demonstrates the overall design procedures from the system conception, cardiac model devising, motion planning, to the motor and accessories selection. This can be used as a reference to aid researchers in the design and construction of their own in-house MCTRs for cardiovascular studies.
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Affiliation(s)
- Yuhui Shi
- a Northwest Institute of Mechanical and Electrical Engineering , Xianyang , Shaanxi Province , China
| | - Theodosios Korakianitis
- b Parks College of Engineering, Aviation and Technology , Saint Louis University , Saint Louis , MO , USA
| | - Zhongjian Li
- c College of Automation , Northwestern Polytechnical University , Xi'an , China
| | - Yubing Shi
- d Faculty of Arts, Science and Technology , University of Northampton , Northampton , UK
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Khoo DPY, Cookson AN, Gill HS, Fraser KH. Normal fluid stresses are prevalent in rotary ventricular assist devices: A computational fluid dynamics analysis. Int J Artif Organs 2018; 41:738-751. [DOI: 10.1177/0391398818792757] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Despite the evolution of ventricular assist devices, ventricular assist device patients still suffer from complications due to the damage to blood by fluid dynamic stress. Since rotary ventricular assist devices are assumed to exert mainly shear stress, studies of blood damage are based on shear flow experiments. However, measurements and simulations of cell and protein deformation show normal and shear stresses deform, and potentially damage, cells and proteins differently. The aim was to use computational fluid dynamics to assess the prevalence of normal stress, in comparison with shear stress, in rotary ventricular assist devices. Our calculations showed normal stresses do occur in rotary ventricular assist devices: the fluid volumes experiencing normal stress above 10 Pa were 0.011 mL (0.092%) and 0.027 mL (0.39%) for the HeartWare HVAD and HeartMate II (HMII), and normal stresses over 100 Pa were present. However, the shear stress volumes were up to two orders of magnitude larger than the normal stress volumes. Considering thresholds for red blood cell and von Willebrand factor deformation by normal and shear stresses, the fluid volumes causing deformation by normal stress were between 2.5 and 5 times the size of those causing deformation by shear stress. The exposure times to the individual normal stress deformation regions were around 1 ms. The results clearly show, for the first time, that while blood within rotary ventricular assist devices experiences more shear stress at much higher magnitudes as compared with normal stress, there is sufficient normal stress exposure present to cause deformation of, and potentially damage to, the blood components. This study is the first to quantify the fluid stress components in real blood contacting devices.
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Affiliation(s)
- Dominica PY Khoo
- Department of Mechanical Engineering, University of Bath, Bath, UK
| | - Andrew N Cookson
- Department of Mechanical Engineering, University of Bath, Bath, UK
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Ng BC, Kleinheyer M, Smith PA, Timms D, Cohn WE, Lim E. Pulsatile operation of a continuous-flow right ventricular assist device (RVAD) to improve vascular pulsatility. PLoS One 2018; 13:e0195975. [PMID: 29677212 PMCID: PMC5909905 DOI: 10.1371/journal.pone.0195975] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 04/03/2018] [Indexed: 11/18/2022] Open
Abstract
Despite the widespread acceptance of rotary blood pump (RBP) in clinical use over the past decades, the diminished flow pulsatility generated by a fixed speed RBP has been regarded as a potential factor that may lead to adverse events such as vasculature stiffening and hemorrhagic strokes. In this study, we investigate the feasibility of generating physiological pulse pressure in the pulmonary circulation by modulating the speed of a right ventricular assist device (RVAD) in a mock circulation loop. A rectangular pulse profile with predetermined pulse width has been implemented as the pump speed pattern with two different phase shifts (0% and 50%) with respect to the ventricular contraction. In addition, the performance of the speed modulation strategy has been assessed under different cardiovascular states, including variation in ventricular contractility and pulmonary arterial compliance. Our results indicated that the proposed pulse profile with optimised parameters (Apulse = 10000 rpm and ωmin = 3000 rpm) was able to generate pulmonary arterial pulse pressure within the physiological range (9–15 mmHg) while avoiding undesirable pump backflow under both co- and counter-pulsation modes. As compared to co-pulsation, stroke work was reduced by over 44% under counter-pulsation, suggesting that mechanical workload of the right ventricle can be efficiently mitigated through counter-pulsing the pump speed. Furthermore, our results showed that improved ventricular contractility could potentially lead to higher risk of ventricular suction and pump backflow, while stiffening of the pulmonary artery resulted in increased pulse pressure. In conclusion, the proposed speed modulation strategy produces pulsatile hemodynamics, which is more physiologic than continuous blood flow. The findings also provide valuable insight into the interaction between RVAD speed modulation and the pulmonary circulation under various cardiovascular states.
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Affiliation(s)
- Boon C. Ng
- Department of Biomedical Engineering, University of Malaya, Kuala Lumpur, Malaysia
- Texas Heart Institute, Houston, Texas, United States of America
| | | | - Peter A. Smith
- Texas Heart Institute, Houston, Texas, United States of America
| | - Daniel Timms
- BiVACOR, Inc, Houston, Texas, United States of America
| | - William E. Cohn
- Texas Heart Institute, Houston, Texas, United States of America
| | - Einly Lim
- Department of Biomedical Engineering, University of Malaya, Kuala Lumpur, Malaysia
- * E-mail:
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HVAD Flow Waveform Morphologies: Theoretical Foundation and Implications for Clinical Practice. ASAIO J 2018; 63:526-535. [PMID: 28323662 PMCID: PMC5585123 DOI: 10.1097/mat.0000000000000557] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Continuous-flow ventricular assist device (cfVAD) performance and patient hemodynamic conditions are intimately interrelated and dynamic, changing frequently with alterations in physiologic conditions, particularly pre- and afterloading conditions. The Heartware cfVAD (HVAD) provides a unique feature among currently approved VADs of providing an estimated instantaneous flow waveform, the characteristics of which can provide significant insights into patient and device properties. Despite being readily available, HVAD waveforms are poorly understood, underutilized, and insufficiently leveraged, even by clinicians who regularly manage HVAD patients. The purpose of this review is to provide the theoretical foundation for understanding the determinants of HVAD waveform characteristics and to provide practical examples illustrating how to interpret and integrate changes of HVAD waveforms into clinical practice. Heartware cfVAD waveforms should be considered a complimentary tool for the optimization of medical therapies and device speed in HVAD patients.
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Chen Z, Jena SK, Giridharan GA, Koenig SC, Slaughter MS, Griffith BP, Wu ZJ. Flow features and device-induced blood trauma in CF-VADs under a pulsatile blood flow condition: A CFD comparative study. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2018; 34:10.1002/cnm.2924. [PMID: 28859253 PMCID: PMC5803368 DOI: 10.1002/cnm.2924] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Revised: 07/28/2017] [Accepted: 08/28/2017] [Indexed: 05/11/2023]
Abstract
In this study, the flow features and device-associated blood trauma in 4 clinical ventricular assist devices (VADs; 2 implantable axial VADs, 1 implantable centrifugal VAD, and 1 extracorporeal VAD) were computationally analyzed under clinically relevant pulsatile flow conditions. The 4 VADs were operated at fixed pump speed at a mean rate of 4.5 L/min. Mean pressure difference, wall shear stress, volume distribution of scalar shear stress (SSS), and shear-induced hemolysis index (HI) were derived from the flow field of each VAD and were compared. The computationally predicted mean pressure difference across the 3 implantable VADs was ~70 mmHg, and the extracorporeal VAD was ~345 mmHg, which matched well with their reported pressure-flow curves. The axial VADs had higher mean wall shear stress and SSS compared with the centrifugal VADs. However, the residence time of the centrifugal VADs was much longer compared with the axial VADs because of the large volume of the centrifugal VADs. The highest SSS was observed in one axial VAD, and the longest exposure time was observed in 1 centrifugal VAD. These 2 VADs generated the highest HI. The shear-induced HI varied as a function of flow rate within each cardiac cycle. At fixed pump speed, the HI was greatest at low flow rate due to longer exposure time to shear stress compared with at high flow rate. Subsequently, we hypothesize that to reduce the risk of blood trauma during VAD support, shear stress magnitude and exposure time need to be minimized.
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Affiliation(s)
- Zengsheng Chen
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Sofen K Jena
- Department of Cardiovascular and Thoracic Surgery, School of Medicine, University of Louisville, Louisville, KY, 40202, USA
| | - Guruprasad A Giridharan
- Department of Bioengineering, Speed School of Engineering, University of Louisville, Louisville, KY, 40292, USA
| | - Steven C Koenig
- Department of Cardiovascular and Thoracic Surgery, School of Medicine, University of Louisville, Louisville, KY, 40202, USA
- Department of Bioengineering, Speed School of Engineering, University of Louisville, Louisville, KY, 40292, USA
| | - Mark S Slaughter
- Department of Cardiovascular and Thoracic Surgery, School of Medicine, University of Louisville, Louisville, KY, 40202, USA
- Department of Bioengineering, Speed School of Engineering, University of Louisville, Louisville, KY, 40292, USA
| | - Bartley P Griffith
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Zhongjun J Wu
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
- Fischell Department of Bioengineering, A James Clark School of Engineering, University of Maryland, College Park, MD, 20742, USA
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Bowles CT, Hards R, Wrightson N, Lincoln P, Kore S, Marley L, Dalzell JR, Raj B, Baker TA, Goodwin D, Carroll P, Pateman J, Black JJM, Kattenhorn P, Faulkner M, Parameshwar J, Butcher C, Mason M, Rosenberg A, McGovern I, Weymann A, Gwinnutt C, Banner NR, Schueler S, Simon AR, Pitcher DW. Algorithms to guide ambulance clinicians in the management of emergencies in patients with implanted rotary left ventricular assist devices. Emerg Med J 2017; 34:842-850. [PMID: 29127102 PMCID: PMC5750371 DOI: 10.1136/emermed-2016-206172] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 07/27/2017] [Accepted: 09/02/2017] [Indexed: 11/04/2022]
Abstract
Advances in left ventricular assist device (LVAD) therapy have resulted in increasing numbers of adult LVAD recipients in the community. However, device failure, stroke, bleeding, LVAD thrombosis and systemic infection can be life-threatening emergencies. Currently, four LVAD systems are implanted in six UK transplant centres, each of which provides device-specific information to local emergency services. This has resulted in inconsistent availability and content of information with the risks of delayed or inappropriate decision-making. In order to improve patient safety, a consortium of UK healthcare professionals with expertise in LVADs developed universally applicable prehospital emergency algorithms. Guidance was framed as closely as possible on the standard ABCDE approach to the assessment of critically ill patients.
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Affiliation(s)
- Christopher T Bowles
- Department of Cardiothoracic Transplantation and Mechanical Circulatory Support, Royal Brompton and Harefield NHS Foundation Trust, London, UK
| | - Rachel Hards
- Department of Cardiothoracic Transplantation and Mechanical Circulatory Support, Royal Brompton and Harefield NHS Foundation Trust, London, UK
| | - Neil Wrightson
- Department of Cardiothoracic Transplantation, Freeman Hospital, Newcastle upon Tyne, UK
| | - Paul Lincoln
- Department of Cardiothoracic Transplantation, Papworth Hospital NHS Foundation Trust, Cambridge, UK
| | - Shishir Kore
- Department of Cardiothoracic Transplantation, Wythenshawe Hospital, University Hospital of South Manchester NHS Foundation Trust, Manchester, UK
| | - Laura Marley
- Department of Cardiothoracic Transplantation, Queen Elizabeth Hospital Birmingham, Birmingham, UK
| | - Jonathan R Dalzell
- Scottish Advanced Heart Failure Service, Golden Jubilee National Hospital, Glasgow, UK
| | - Binu Raj
- Department of Cardiothoracic Transplantation and Mechanical Circulatory Support, Royal Brompton and Harefield NHS Foundation Trust, London, UK
| | - Tracey A Baker
- Department of Cardiothoracic Transplantation and Mechanical Circulatory Support, Royal Brompton and Harefield NHS Foundation Trust, London, UK
| | - Diane Goodwin
- Department of Cardiothoracic Transplantation, Papworth Hospital NHS Foundation Trust, Cambridge, UK
| | - Petra Carroll
- Department of Cardiothoracic Transplantation and Mechanical Circulatory Support, Royal Brompton and Harefield NHS Foundation Trust, London, UK
| | - Jane Pateman
- Anaesthetic Department, Royal Sussex County Hospital, Brighton, UK
| | - John J M Black
- Clinical Directorate, South Central Ambulance Service Foundation Trust, Oxfordshire, UK
| | - Paul Kattenhorn
- East of England Ambulance Service Headquarters, Whiting Way, Melbourn, Cambs., SG8 6EN., East of England Ambulance Service Headquarters, Melbourn, Cambs, UK
| | - Mark Faulkner
- London Ambulance Service, Medical Directorate Office, London, UK
| | - Jayan Parameshwar
- Department of Cardiothoracic Transplantation, Papworth Hospital NHS Foundation Trust, Cambridge, UK
| | - Charles Butcher
- Department of Cardiothoracic Transplantation and Mechanical Circulatory Support, Royal Brompton and Harefield NHS Foundation Trust, London, UK
| | - Mark Mason
- Department of Cardiothoracic Transplantation and Mechanical Circulatory Support, Royal Brompton and Harefield NHS Foundation Trust, London, UK
| | - Alexander Rosenberg
- Department of Cardiothoracic Transplantation and Mechanical Circulatory Support, Royal Brompton and Harefield NHS Foundation Trust, London, UK
| | - Ian McGovern
- Department of Cardiothoracic Transplantation and Mechanical Circulatory Support, Royal Brompton and Harefield NHS Foundation Trust, London, UK
| | - Alexander Weymann
- Department of Cardiothoracic Transplantation and Mechanical Circulatory Support, Royal Brompton and Harefield NHS Foundation Trust, London, UK
| | | | - Nicholas R Banner
- Department of Cardiothoracic Transplantation and Mechanical Circulatory Support, Royal Brompton and Harefield NHS Foundation Trust, London, UK
| | - Stephan Schueler
- Department of Cardiothoracic Transplantation, Freeman Hospital, Newcastle upon Tyne, UK
| | - Andre R Simon
- Department of Cardiothoracic Transplantation and Mechanical Circulatory Support, Royal Brompton and Harefield NHS Foundation Trust, London, UK
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Mueller I, Jansen-Park SH, Neidlin M, Steinseifer U, Abel D, Autschbach R, Rossaint R, Schmitz-Rode T, Sonntag SJ. Design of a right ventricular mock circulation loop as a test bench for right ventricular assist devices. ACTA ACUST UNITED AC 2017; 62:131-137. [PMID: 27987352 DOI: 10.1515/bmt-2016-0104] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Accepted: 10/27/2016] [Indexed: 11/15/2022]
Abstract
Right heart failure (RHF), e.g. due to pulmonary hypertension (PH), is a serious health issue with growing occurrence and high mortality rate. Limited efficacy of medication in advanced stages of the disease constitutes the need for mechanical circulatory support of the right ventricle (RV). An essential contribution to the process of developing right ventricular assist devices (RVADs) is the in vitro test bench, which simulates the hemodynamic behavior of the native circulatory system. To model healthy and diseased arterial-pulmonary hemodynamics in adults (mild and severe PH and RHF), a right heart mock circulation loop (MCL) was developed. Incorporating an anatomically shaped silicone RV and a silicone atrium, it not only enables investigations of hemodynamic values but also suction events or the handling of minimal invasive RVADs in an anatomical test environment. Ventricular pressure-volume loops of all simulated conditions as well as pressure and volume waveforms were recorded and compared to literature data. In an exemplary test, an RVAD was connected to the apex to further test the feasibility of studying such devices with the developed MCL. In conclusion, the hemodynamic behavior of the native system was well reproduced by the developed MCL, which is a useful basis for future RVAD tests.
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Affiliation(s)
- Indra Mueller
- Department of Cardiovascular Engineering, Institute of Applied Medical Engineering, RWTH Aachen University, Pauwelsstr.20, 52074 Aachen
| | - So-Hyun Jansen-Park
- Department of Cardiovascular Engineering, Institute of Applied Medical Engineering, RWTH Aachen University, 52074 Aachen
| | - Michael Neidlin
- Department of Cardiovascular Engineering, Institute of Applied Medical Engineering, RWTH Aachen University, 52074 Aachen
| | - Ulrich Steinseifer
- Department of Cardiovascular Engineering, Institute of Applied Medical Engineering, RWTH Aachen University, 52074 Aachen
| | - Dirk Abel
- Institute of Automatic Control, RWTH Aachen University, 52074 Aachen
| | - Rüdiger Autschbach
- Department of Cardiothoracic and Vascular Surgery, University Hospital RWTH Aachen, 52074 Aachen
| | - Rolf Rossaint
- Department of Anesthesiology, University Hospital RWTH Aachen, 52074 Aachen
| | - Thomas Schmitz-Rode
- Department of Cardiovascular Engineering, Institute of Applied Medical Engineering, RWTH Aachen University, 52074 Aachen
| | - Simon Johannes Sonntag
- Department of Cardiovascular Engineering, Institute of Applied Medical Engineering, RWTH Aachen University, 52074 Aachen
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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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