1
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Meng F, Zhu Y, Yang M. Hemodynamic effects of pulsatile frequency of right ventricular assist device (RVAD) on pulmonary perfusion: a simulation study. Med Biol Eng Comput 2024:10.1007/s11517-024-03174-0. [PMID: 39048840 DOI: 10.1007/s11517-024-03174-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Accepted: 07/14/2024] [Indexed: 07/27/2024]
Abstract
Right ventricular assist devices (RVADs) have been extensively used to provide hemodynamic support for patients with end-stage right heart (RV) failure. However, conventional in-parallel RVADs can lead to an elevation of pulmonary artery (PA) pressure, consequently increasing the right ventricular (RV) afterload, which is unfavorable for the relaxation of cardiac muscles and reduction of valve complications. The aim of this study is to investigate the hemodynamic effects of the pulsatile frequency of the RVAD on pulmonary artery. Firstly, a mathematical model incorporating heart, systemic circulation, pulmonary circulation, and RVAD is developed to simulate the cardiovascular system. Subsequently, the frequency characteristics of the pulmonary circulation system are analyzed, and the calculated results demonstrate that the pulsatile frequency of the RVAD has a substantive impact on the pulmonary artery pressure. Finally, to verify the analysis results, the hemodynamic effects of the pulsatile frequency of the RVAD on pulmonary artery are compared under diffident support modes. It is found that the pulmonary artery pressure decreases by approximately 6% when the pulsatile frequency changes from 1 to 3 Hz. The increased pulsatile frequency of RA-PA support mode may facilitate the opening of the pulmonary valve, while the RV-PA support mode can more effectively reduce the load of RV. This work provides a useful method to decrease the pulmonary artery pressure during the RVAD supports and may be beneficial for improving myocardial function in patients with end-stage right heart failure, especially those with pulmonary hypertension.
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Affiliation(s)
- Fan Meng
- Department of Instrument Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Yuanfei Zhu
- Department of Instrument Science and Engineering, Shanghai Jiao Tong University, Shanghai, China.
| | - Ming Yang
- Department of Instrument Science and Engineering, Shanghai Jiao Tong University, Shanghai, China.
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2
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Dual SA, Cowger J, Roche E, Nayak A. The Future of Durable Mechanical Circulatory Support: Emerging Technological Innovations and Considerations to Enable Evolution of the Field. J Card Fail 2024; 30:596-609. [PMID: 38431185 DOI: 10.1016/j.cardfail.2024.01.011] [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] [Received: 12/22/2023] [Revised: 01/25/2024] [Accepted: 01/26/2024] [Indexed: 03/05/2024]
Abstract
The field of durable mechanical circulatory support (MCS) has undergone an incredible evolution over the past few decades, resulting in significant improvements in longevity and quality of life for patients with advanced heart failure. Despite these successes, substantial opportunities for further improvements remain, including in pump design and ancillary technology, perioperative and postoperative management, and the overall patient experience. Ideally, durable MCS devices would be fully implantable, automatically controlled, and minimize the need for anticoagulation. Reliable and long-term total artificial hearts for biventricular support would be available; and surgical, perioperative, and postoperative management would be informed by the individual patient phenotype along with computational simulations. In this review, we summarize emerging technological innovations in these areas, focusing primarily on innovations in late preclinical or early clinical phases of study. We highlight important considerations that the MCS community of clinicians, engineers, industry partners, and venture capital investors should consider to sustain the evolution of the field.
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Affiliation(s)
- Seraina A Dual
- KTH Royal Institute of Technology, Department of Biomedical Engineering and Health Systems, Stockholm, Sweden
| | | | - Ellen Roche
- Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Aditi Nayak
- Baylor University Medical Center, Dallas, Texas.
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3
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Grinstein J, Belkin MN, Kalantari S, Bourque K, Salerno C, Pinney S. Adverse Hemodynamic Consequences of Continuous Left Ventricular Mechanical Support: JACC Review Topic of the Week. J Am Coll Cardiol 2023; 82:70-81. [PMID: 37380306 DOI: 10.1016/j.jacc.2023.04.045] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 04/11/2023] [Accepted: 04/14/2023] [Indexed: 06/30/2023]
Abstract
Left ventricular assist devices (LVADs) provide lifesaving therapy for patients with advanced heart failure. The recognition of pump thrombosis, stroke, and nonsurgical bleeding as hemocompatibility-related adverse events (HRAEs) led to pump design improvements and reduced adverse event rates. However, continuous flow can predispose patients to right-sided heart failure (RHF) and aortic insufficiency (AI), especially as patients live longer with their device. Given the hemodynamic contributions to AI and RHF, these comorbidities can be classified as hemodynamic-related events (HDREs). Hemodynamic-driven events are time dependent and often manifest later than HRAEs. This review examines the emerging strategies to mitigate HDREs, with a focus on defining best practices for AI and RHF. As we head into the next generation of LVAD technology, it is important to differentiate HDREs from HRAEs so that we can continue to advance the field and improve the true durability of the pump-patient continuum.
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Affiliation(s)
- Jonathan Grinstein
- Section of Cardiology, Department of Medicine, University of Chicago, Chicago, Illinois, USA.
| | - Mark N Belkin
- Section of Cardiology, Department of Medicine, University of Chicago, Chicago, Illinois, USA
| | - Sara Kalantari
- Section of Cardiology, Department of Medicine, University of Chicago, Chicago, Illinois, USA
| | - Kevin Bourque
- Heart Failure Division, Abbott, Burlington, Massachusetts, USA
| | - Christopher Salerno
- Section of Cardiac Surgery, Department of Surgery, University of Chicago, Chicago, Illinois, USA
| | - Sean Pinney
- Section of Cardiology, Department of Medicine, University of Chicago, Chicago, Illinois, USA
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4
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Ozturk C, Rosalia L, Roche ET. A Multi-Domain Simulation Study of a Pulsatile-Flow Pump Device for Heart Failure With Preserved Ejection Fraction. Front Physiol 2022; 13:815787. [PMID: 35145432 PMCID: PMC8822361 DOI: 10.3389/fphys.2022.815787] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 01/05/2022] [Indexed: 12/02/2022] Open
Abstract
Mechanical circulatory support (MCS) devices are currently under development to improve the physiology and hemodynamics of patients with heart failure with preserved ejection fraction (HFpEF). Most of these devices, however, are designed to provide continuous-flow support. While it has been shown that pulsatile support may overcome some of the complications hindering the clinical translation of these devices for other heart failure phenotypes, the effects that it may have on the HFpEF physiology are still unknown. Here, we present a multi-domain simulation study of a pulsatile pump device with left atrial cannulation for HFpEF that aims to alleviate left atrial pressure, commonly elevated in HFpEF. We leverage lumped-parameter modeling to optimize the design of the pulsatile pump, computational fluid dynamic simulations to characterize hydraulic and hemolytic performance, and finite element modeling on the Living Heart Model to evaluate effects on arterial, left atrial, and left ventricular hemodynamics and biomechanics. The findings reported in this study suggest that pulsatile-flow support can successfully reduce pressures and associated wall stresses in the left heart, while yielding more physiologic arterial hemodynamics compared to continuous-flow support. This work therefore supports further development and evaluation of pulsatile support MCS devices for HFpEF.
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Affiliation(s)
- Caglar Ozturk
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Luca Rosalia
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, United States
- Health Sciences and Technology Program, Harvard – Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Ellen T. Roche
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, United States
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, United States
- *Correspondence: Ellen T. Roche,
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5
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Zhu Y, Yang M, Zhang Y, Meng F, Yang T, Fang Z. Effects of Pulsatile Frequency of Left Ventricular Assist Device (LVAD) on Coronary Perfusion: A Numerical Simulation Study. Med Sci Monit 2020; 26:e925367. [PMID: 32940255 PMCID: PMC7521069 DOI: 10.12659/msm.925367] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Background Left ventricular assist devices (LVADs) with counter-pulsation mode have been widely used to support left ventricular function and improve coronary circulation. However, the frequency characteristics of the coronary system have not been considered. The aim of this study was to investigate the effects of pulsatile frequency of LVADs on coronary perfusion. Material/Methods First, a lumped parameter (LP) model incorporating coronary circulation, systemic circulation, left heart, and LVAD was established to simulate the cardiovascular system. Then, the frequency characteristics of the coronary system were analyzed and the calculation results showed that the pulsatile frequency of the LVAD has a substantial effect on coronary blood flow. To verify the accuracy of the theoretical analysis, the hemodynamic effects of the LVAD on the coronary artery were compared under 4 support modes: co-pulsation mode, and counter-pulsation modes in synchronization ratios of 1: 1, 2: 1, and 3: 1. Results We found that the coronary flow increased by 5% when the working mode changed from co-pulsation to counter-pulsation in a synchronization ratio of 1: 1, and by an additional 6% when the working mode changed from counter-pulsation in a synchronization ratio of 1: 1 to counter-pulsation in a synchronization ratio of 3: 1. Conclusions This work provides a useful method to increase coronary perfusion and may be beneficial for improving myocardial function in patients with end-stage heart failure, especially those with ischemic cardiomyopathy (ICM).
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Affiliation(s)
- Yuanfei Zhu
- Department of Instrument Science and Engineering, Shanghai Jiao Tong University, Shanghai, China (mainland)
| | - Ming Yang
- Department of Instrument Science and Engineering, Shanghai Jiao Tong University, Shanghai, China (mainland)
| | - Yan Zhang
- Department of Cardiovascular Surgery, Cardiovascular Institute and Fu Wai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China (mainland)
| | - Fan Meng
- Department of Instrument Science and Engineering, Shanghai Jiao Tong University, Shanghai, China (mainland)
| | - Tianyue Yang
- Department of Instrument Science and Engineering, Shanghai Jiao Tong University, Shanghai, China (mainland)
| | - Zhiwei Fang
- Department of Instrument Science and Engineering, Shanghai Jiao Tong University, Shanghai, China (mainland)
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6
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Jain P, Shehab S, Muthiah K, Robson D, Granegger M, Drakos SG, Jansz P, Macdonald PS, Hayward CS. Insights Into Myocardial Oxygen Consumption, Energetics, and Efficiency Under Left Ventricular Assist Device Support Using Noninvasive Pressure-Volume Loops. Circ Heart Fail 2019; 12:e006191. [DOI: 10.1161/circheartfailure.119.006191] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background:
Assessment of left ventricular (LV) recovery under continuous-flow LV assist device therapy is hampered by concomitant pump support. We describe derivation of noninvasive pressure-volume loops in continuous-flow LV assist device patients and demonstrate an application in the assessment of recovery.
Methods and Results:
Using pump controller parameters and noninvasive arterial pressure waveforms, central aortic pressure, outflow conduit pressure gradient, and instantaneous LV pressure were calculated. Instantaneous LV volumes were calculated from echocardiographic LV end-diastolic volume accounting for the integral of pump flow with respect to time and aortic ejection volume derived from the pump speed waveform. Pressure-volume loops were derived during pump speed adjustment and following bolus intravenous milrinone to assess changes in loading conditions and contractility, respectively. Fourteen patients were studied. Baseline noninvasive LV end-diastolic pressure correlated with invasive pulmonary arterial wedge pressure (
r
2
=0.57, root mean square error 5.0 mm Hg,
P
=0.003). Measured noninvasively, milrinone significantly increased LV ejection fraction (40.3±13.6% versus 36.8±14.2%,
P
<0.0001), maximum dP/dt (623±126 versus 555±122 mm Hg/s,
P
=0.006), and end-systolic elastance (1.03±0.57 versus 0.89±0.38 mm Hg/mL,
P
=0.008), consistent with its expected inotropic effect. Milrinone reduced myocardial oxygen consumption (0.15±0.06 versus 0.16±0.07 mL/beat,
P
=0.003) and improved myocardial efficiency (43.7±14.0% versus 41.2±15.5%,
P
=0.001). Reduced pump speed caused increased LV end-diastolic volume (190±80 versus 165±71 mL,
P
<0.0001) and LV end-diastolic pressure (14.3±10.2 versus 9.9±9.3 mm Hg,
P
=0.024), consistent with a predictable increase in preload. There was increased myocardial oxygen consumption (0.16±0.07 versus 0.14±0.06 mL O
2
/beat,
P
<0.0001) despite unchanged stroke work (
P
=0.24), reflecting decreased myocardial efficiency (39.2±12.7% versus 45.2±17.0%,
P
=0.003).
Conclusions:
Pressure-volume loops are able to be derived noninvasively in patients with the HeartWare HVAD and can detect induced changes in load and contractility.
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Affiliation(s)
- Pankaj Jain
- Cardiology Department, St Vincent’s Hospital, Sydney, Australia (P.J., S.S., K.M., D.R., P.J., P.S.M., C.S.H.)
| | - Sajad Shehab
- Cardiology Department, St Vincent’s Hospital, Sydney, Australia (P.J., S.S., K.M., D.R., P.J., P.S.M., C.S.H.)
| | - Kavitha Muthiah
- Cardiology Department, St Vincent’s Hospital, Sydney, Australia (P.J., S.S., K.M., D.R., P.J., P.S.M., C.S.H.)
| | - Desiree Robson
- Cardiology Department, St Vincent’s Hospital, Sydney, Australia (P.J., S.S., K.M., D.R., P.J., P.S.M., C.S.H.)
| | - Marcus Granegger
- Institute for Imaging Science and Computational Modelling in Cardiovascular Medicine, Charitè Universitätsmedizin, Berlin, Germany (M.G.)
| | | | - Paul Jansz
- Cardiology Department, St Vincent’s Hospital, Sydney, Australia (P.J., S.S., K.M., D.R., P.J., P.S.M., C.S.H.)
| | - Peter S. Macdonald
- Cardiology Department, St Vincent’s Hospital, Sydney, Australia (P.J., S.S., K.M., D.R., P.J., P.S.M., C.S.H.)
| | - Christopher S. Hayward
- Cardiology Department, St Vincent’s Hospital, Sydney, Australia (P.J., S.S., K.M., D.R., P.J., P.S.M., C.S.H.)
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7
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Her K, Kim JY, Lim KM, Choi SW. Windkessel model of hemodynamic state supported by a pulsatile ventricular assist device in premature ventricle contraction. Biomed Eng Online 2018; 17:18. [PMID: 29394944 PMCID: PMC5797383 DOI: 10.1186/s12938-018-0440-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Accepted: 01/10/2018] [Indexed: 11/15/2022] Open
Abstract
Background Counter-pulsation control (CPC) by ventricular assist devices (VADs) is believed to reduce cardiac load and increase coronary perfusion. However, patients with VADs have a higher risk of arrhythmia, which may cause the CPC to fail. Consequently, CPC has not been applied by VADs in clinical practice. The phase-locked loop (PLL) algorithm for CPC is readily implemented in VADs; however, it requires a normal, consistent heartbeat for adequate performance. When an arrhythmia occurs, the algorithm maintains a constant pumping rate despite the unstable heartbeat. Therefore, to apply the PLL algorithm to CPC, the hemodynamic effects of abnormal heartbeats must be analyzed. Objectives This study sought to predict the hemodynamic effects in patients undergoing CPC using VADs, based on electrocardiogram (ECG) data, including a wide range of heart rate (HR) changes caused by premature ventricular contraction (PVC) or other reasons. Methods A four-element Windkessel hemodynamic model was used to reproduce the patient’s aortic blood pressure in this study. ECG data from 15 patients with severe congestive heart failure were used to assess the effect of the CPC on the patients’ hemodynamic state. The input and output flow characteristics of the pulsatile VAD (LibraHeart I, Cervika, Korea) were measured using an ultrasound blood flow meter (TS410, Transonic, USA), with the aortic pressure maintained at 80–120 mmHg. All other patient conditions were also reproduced. Results In patients with PVCs or normal heartbeats, CPC controlled by a VAD reduced the cardiac load by 20 and 40%, respectively. When the HR was greater for other reasons, such as sinus tachycardia, simultaneous ejection from the heart and VAD was observed; however, the cardiac load was not increased by rapid cardiac contractions resulting from decreased left ventricle volume. These data suggest that the PLL algorithm reduces the cardiac load and maintains consistent hemodynamic changes.
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Affiliation(s)
- Keun Her
- Department of Cardiovascular and Thoracic Surgery, Soonchunhyang University Hospital, Bucheon-si, Republic of Korea
| | - Joon Yeong Kim
- Program of Mechanical and Biomedical Engineering, College of Engineering, Kangwon National University, Chuncheon-si, Republic of Korea
| | - Ki Moo Lim
- Department of Medical IT Convergence Engineering, Kumoh National Institute of Technology, Gumi, Republic of Korea
| | - Seong Wook Choi
- Program of Mechanical and Biomedical Engineering, College of Engineering, Kangwon National University, Chuncheon-si, Republic of Korea.
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8
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Kim YS, Yuniarti AR, Song KS, Trayanova NA, Shim EB, Lim KM. Computational analysis of the effect of mitral and aortic regurgitation on the function of ventricular assist devices using 3D cardiac electromechanical model. Med Biol Eng Comput 2017; 56:889-898. [PMID: 29080191 PMCID: PMC5906511 DOI: 10.1007/s11517-017-1727-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 04/19/2017] [Indexed: 11/15/2022]
Abstract
Valvular insufficiency affects cardiac responses and the pumping efficacy of left ventricular assist devices (LVADs) when patients undergo LVAD therapy. Knowledge of the effect of valvular regurgitation on the function of LVADs is important when treating heart failure patients. The goal of this study was to examine the effect of valvular regurgitation on the ventricular mechanics of a heart under LVAD treatment and the pumping efficacy of an LVAD using a computational model of the cardiovascular system. For this purpose, a 3D electromechanical model of failing ventricles in a human heart was coupled with a lumped-parameter model of valvular regurgitation and an LVAD-implanted vascular system. We used the computational model to predict cardiac responses with respect to the severity of valvular regurgitation in the presence of LVAD treatment. An LVAD could reduce left ventricle (LV) pressure (up to 34%) and end-diastolic ventricular volume (up to 80%) and maintain cardiac output at the estimated flow rate from the LVAD under the condition of mitral regurgitation (MR); however, the opposite would occur under the condition of aortic regurgitation (AR). Considering these physiological responses, we conclude that AR, and not MR, diminishes the pumping function of LVADs.
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Affiliation(s)
- Yoo Seok Kim
- Department of IT Convergence Engineering, Kumoh National Institute of Technology, 61 Daehak-ro, Gumi, Gyeongbuk, 39253, Republic of South Korea
| | - Ana R Yuniarti
- Department of IT Convergence Engineering, Kumoh National Institute of Technology, 61 Daehak-ro, Gumi, Gyeongbuk, 39253, Republic of South Korea
| | - Kwang-Soup Song
- Department of Medical IT Convergence Engineering, Kumoh National Institute of Technology, Gumi, Republic of South Korea
| | - Natalia A Trayanova
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Eun Bo Shim
- Department of Mechanical & Biomedical Engineering, Kangwon National University, Chuncheon, Republic of South Korea
| | - Ki Moo Lim
- Department of IT Convergence Engineering, Kumoh National Institute of Technology, 61 Daehak-ro, Gumi, Gyeongbuk, 39253, Republic of South Korea.
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9
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Computational Analysis of Pumping Efficacy of a Left Ventricular Assist Device according to Cannulation Site in Heart Failure with Valvular Regurgitation. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2016; 2016:6930482. [PMID: 28115981 PMCID: PMC5221291 DOI: 10.1155/2016/6930482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Revised: 11/04/2016] [Accepted: 12/05/2016] [Indexed: 11/18/2022]
Abstract
Mitral valve regurgitation (MR) causes blood to flow in two directions during contraction of the left ventricle (LV), that is, forward into the aorta and backward into the left atrium (LA). In aortic valve regurgitation (AR), leakage occurs from the aorta into the LV during diastole. Our objective is to analyze the contribution of a left ventricular assist device (LVAD) to MR and AR for the following two different cannulation sites: from the LA to the aorta (LAAO) and from the LV to the aorta (LVAO). Using a computational method, we simulated three ventricular conditions (normal [HF without valvular regurgitation], 5% MR, and 5% AR) in three groups (control [no LVAD], LAAO, and LVAO). The results showed that LVAD with LAAO cannulation is appropriate for recovery of the MR heart, and the LVAD with LVAO cannulation is appropriate for treating the AR heart.
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10
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Neidlin M, Corsini C, Sonntag SJ, Schulte-Eistrup S, Schmitz-Rode T, Steinseifer U, Pennati G, Kaufmann TAS. Hemodynamic analysis of outflow grafting positions of a ventricular assist device using closed-loop multiscale CFD simulations: Preliminary results. J Biomech 2016; 49:2718-2725. [PMID: 27298155 DOI: 10.1016/j.jbiomech.2016.06.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Revised: 05/30/2016] [Accepted: 06/01/2016] [Indexed: 11/17/2022]
Abstract
Subclavian arteries are a possible alternate location for left ventricular assist device (LVAD) outflow grafts due to easier surgical access and application in high risk patients. As vascular blood flow mechanics strongly influence the clinical outcome, insights into the hemodynamics during LVAD support can be used to evaluate different grafting locations. In this study, the feasibility of left and right subclavian artery (SA) grafting was investigated for the HeartWare HVAD with a numerical multiscale model. A 3-D CFD model of the aortic arch was coupled to a lumped parameter model of the cardiovascular system under LVAD support. Grafts in the left and right SA were placed at three different anastomoses angles (90°, 60° and 30°). Additionally, standard grafting of the ascending and descending aorta was modelled. Full support LVAD (5l/min) and partial support LVAD (3l/min) in co-pulsation and counter-pulsation mode were analysed. The grafting positions were investigated regarding coronary and cerebral perfusion. Furthermore, the influence of the anastomosis angle on wall shear stress (WSS) was evaluated. Grafting of left or right subclavian arteries has similar hemodynamic performance in comparison to standard cannula positions. Angularity change of the graft anastomosis from 90° to 30° slightly increases the coronary and cerebral blood flow by 6-9% while significantly reduces the WSS by 35%. Cannulation of the SA is a feasible anastomosis location for the HVAD in the investigated vessel geometry.
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Affiliation(s)
- Michael Neidlin
- Department of Cardiovascular Engineering, Institute of Applied Medical Engineering, Helmholtz Institute, RWTH Aachen University, Aachen, Germany; Enmodes GmbH, Aachen, Germany.
| | - Chiara Corsini
- Laboratory of Biological Structure Mechanics, Department of Chemistry, Materials and Chemical Engineering ''Giulio Natta'', Politecnico di Milano, Milano, Italy
| | - Simon J Sonntag
- Department of Cardiovascular Engineering, Institute of Applied Medical Engineering, Helmholtz Institute, RWTH Aachen University, Aachen, Germany; Enmodes GmbH, Aachen, Germany
| | | | - Thomas Schmitz-Rode
- Department of Cardiovascular Engineering, Institute of Applied Medical Engineering, Helmholtz Institute, RWTH Aachen University, Aachen, Germany
| | - Ulrich Steinseifer
- Department of Cardiovascular Engineering, Institute of Applied Medical Engineering, Helmholtz Institute, RWTH Aachen University, Aachen, Germany
| | - Giancarlo Pennati
- Laboratory of Biological Structure Mechanics, Department of Chemistry, Materials and Chemical Engineering ''Giulio Natta'', Politecnico di Milano, Milano, Italy
| | - Tim A S Kaufmann
- Department of Cardiovascular Engineering, Institute of Applied Medical Engineering, Helmholtz Institute, RWTH Aachen University, Aachen, Germany; Enmodes GmbH, Aachen, Germany
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11
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Kim YS, Kim EH, Kim HG, Shim EB, Song KS, Lim KM. Mathematical analysis of the effects of valvular regurgitation on the pumping efficacy of continuous and pulsatile left ventricular assist devices. Integr Med Res 2016; 5:22-29. [PMID: 28462093 PMCID: PMC5381421 DOI: 10.1016/j.imr.2016.01.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Revised: 12/31/2015] [Accepted: 01/01/2016] [Indexed: 11/26/2022] Open
Abstract
We numerically investigated the physiological relationship between the severity of regurgitation and the effect of a left ventricular assist device (LVAD) on cardiovascular system responses. Under conditions of mitral regurgitation, the effects of both pulsatile and continuous LVAD treatment on ventricular unloading were significant. Under conditions of aortic regurgitation (AR), the effects of the LVADs on ventricular unloading were not significant. The effects of LVAD treatment decreased according to the severity of AR.
Background A left ventricular assist device (LVAD) is normally contraindicated in significant aortic regurgitation (AR) and requires intraoperative valve repair or exclusion. Nevertheless, AR can coexist with an LVAD, so a valid question when asked might still be of clinical significance. The purpose of this study is to analyze the effects of valve regurgitation on the pumping efficacy of continuous and pulsatile LVADs with a computational method. Methods A cardiovascular model was developed based on the Windkessel model, which reflects the hemodynamic flow resistance and the blood wall elasticity. Using the Windkessel model, important cardiovascular components, such as the right atrium, right ventricle, pulmonary artery, pulmonary vein, left atrium (LA), left ventricle (LV), aorta, and branching blood vessels, were expressed. Results In the case of AR, continuous and pulsatile LVADs improved cardiac output and reduced mechanical load slightly. In the case of mitral regurgitation, the LVADs improved cardiac output (cardiac outputs were about 5 L/min regardless of the severity of regurgitation) and reduced afterload significantly. Conclusion AR reduced both continuous and pulsatile LVAD function significantly while mitral regurgitation did not affect their pumping efficacy.
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Affiliation(s)
- Yoo Seok Kim
- Department of Medical IT Convergence Engineering, Kumoh National Institute of Technology, Gumi, Korea
| | - Eun-Hye Kim
- Department of Medical IT Convergence Engineering, Kumoh National Institute of Technology, Gumi, Korea
| | - Hyeong-Gyun Kim
- Department of Radiological Science, Far East University, Eumseong, Korea
| | - Eun Bo Shim
- Department of Mechanical and Biomedical Engineering, Kangwon National University, Chuncheon, Korea
| | - Kwang-Soup Song
- Department of Medical IT Convergence Engineering, Kumoh National Institute of Technology, Gumi, Korea
| | - Ki Moo Lim
- Department of Medical IT Convergence Engineering, Kumoh National Institute of Technology, Gumi, Korea
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12
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The Influence of Different Operating Conditions on the Blood Damage of a Pulsatile Ventricular Assist Device. ASAIO J 2015; 61:656-63. [DOI: 10.1097/mat.0000000000000261] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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13
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Multi-objective optimization of pulsatile ventricular assist device hemocompatibility based on neural networks and a genetic algorithm. Int J Artif Organs 2015; 38:325-336. [PMID: 26242848 DOI: 10.5301/ijao.5000419] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/15/2015] [Indexed: 11/20/2022]
Abstract
PURPOSE Given the benefit of pulsatile blood flow for perfusion of coronary arteries and end organs, pulsatile ventricular assist devices (VADs) are still widely used as paracorporeal mechanical circulatory support devices in clinical applications. However, poor hemocompatibility limits the service period of the VADs. Most previous improvements on VAD hemocompatibility were conducted by trial-and-error CFD analysis, which does not easily arrive at the best solution. METHODS In this paper, a multi-objective optimization method integrating neural networks and NSGA-II (Non-dominated Sorted Genetic Algorithm-II) based on FSI simulation was developed and applied to a pulsatile VAD to optimize its hemocompatibility. First, the VAD blood chamber was parameterized with the principal geometrical parameters. Three hemocompatibility indices including hemolysis, platelet activation, and platelet deposition were chosen as goal functions. The neural networks were built to fit the nonlinear relationship between goal functions and geometrical parameters. Next, a multi-objective optimization algorithm (NSGA-II) was used to search out the Pareto optimal solutions in the built neural networks. Finally, the best compromise solution was selected from the Pareto optimal solutions by a fuzzy membership approach and validated by FSI simulation. RESULTS The best compromise solution simultaneously possesses an acceptable hemolysis index, platelet activation index, and platelet deposition index, and the corresponding relative errors between the indices predicted by optimization algorithm and the one calculated by FSI simulations are all less than 5%. CONCLUSIONS The results suggest that the proposed multi-objective optimization method has the potential for application in optimizing pulsatile VAD hemocompatibility, and may also be applied to other blood-wetted devices.
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14
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Lim KM, Hong SB, Lee BK, Shim EB, Trayanova N. Computational analysis of the effect of valvular regurgitation on ventricular mechanics using a 3D electromechanics model. J Physiol Sci 2015; 65:159-64. [PMID: 25644379 PMCID: PMC4816651 DOI: 10.1007/s12576-014-0353-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2014] [Accepted: 12/14/2014] [Indexed: 01/29/2023]
Abstract
Using a three-dimensional electromechanical model of the canine ventricles with dyssynchronous heart failure, we investigated the relationship between severity of valve regurgitation and ventricular mechanical responses. The results demonstrated that end-systolic tension in the septum and left ventricular free wall was significantly lower under the condition of mitral regurgitation (MR) than under aortic regurgitation (AR). Stroke work in AR was higher than that in MR. On the other hand, the difference in stroke volume between the two conditions was not significant, indicating that AR may cause worse pumping efficiency than MR in terms of consumed energy and performed work.
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Affiliation(s)
- Ki Moo Lim
- Department of Medical IT Convergence Engineering, Kumoh National Institute of Technology, Gumi, Republic of Korea
| | - Seung-Bae Hong
- Department of Mechanical and Biomedical Engineering, Kangwon National University, 1 Kangwondaehak-gil, Chuncheon-Si, Gangwon-do 200-701 Republic of Korea
| | - Byong Kwon Lee
- Department of Cardiology, Yonsei University Hospital, Seoul, Republic of Korea
| | - Eun Bo Shim
- Department of Mechanical and Biomedical Engineering, Kangwon National University, 1 Kangwondaehak-gil, Chuncheon-Si, Gangwon-do 200-701 Republic of Korea
| | - Natalia Trayanova
- Institute for Computational Medicine and the Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21218 USA
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15
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The study on hemodynamic effect of varied support models of BJUT-II VAD on coronary artery: a primary CFD study. ASAIO J 2014; 60:643-51. [PMID: 25373559 DOI: 10.1097/mat.0000000000000137] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
BJUT-II VAD (Beijing University of Technology ventricular assist device II) is a novel left ventricular assist device. Because of the special connection between the pump and native heart, the hemodynamic effects of BJUT-II VAD on coronary artery are still unclear. Hence, numerical simulations have been conducted to clarify changes in hemodynamic effects of different support modes. A patient-specific left coronary arterial geometric model is reconstructed based on the computed tomography (CT) data. Three support modes, "constant speed mode," "co-pulse mode," and "counter pulse mode," are used in this study. The wall shear stress (WSS), wall shear stress gradient (WSSG), cycle-averaged wall shear stress (avWSS), oscillatory shear index (OSI), and the flow pattern are calculated to evaluate the hemodynamic states of coronary artery. The computational results demonstrate that the hemodynamic states of coronary artery are directly affected by the support modes. The co-pulse modes could achieve the highest blood perfusion (constant speed: 153 ml/min vs. co-pulse: 775 ml/min vs. counter pulse: 140 ml/min) and the highest avWSS (constant speed: 18.1 Pa vs. co-pulse: 42.6 Pa vs. counter pulse: 22.6 Pa). In addition, both the WSS and WSSG at the time of peak blood velocity under the constant speed mode are lower than those under other two support modes. In contrast, the counter pulse mode generates the highest OSI value (constant speed: 0.365 vs. co-pulse: 0.379 vs. counter pulse: 0.426). BJUT-II VAD under co-pulse mode may have benefits for improving coronary perfusion and preventing the development of atherosclerosis; however, the constant speed mode may have benefit for preventing the development of plaque vulnerability.
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Kwon SS, Chung EC, Park JS, Kim GT, Kim JW, Kim KH, Shin ES, Shim EB. A novel patient-specific model to compute coronary fractional flow reserve. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2014; 116:48-55. [PMID: 25256102 DOI: 10.1016/j.pbiomolbio.2014.09.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2014] [Revised: 09/04/2014] [Accepted: 09/07/2014] [Indexed: 10/24/2022]
Abstract
The fractional flow reserve (FFR) is a widely used clinical index to evaluate the functional severity of coronary stenosis. A computer simulation method based on patients' computed tomography (CT) data is a plausible non-invasive approach for computing the FFR. This method can provide a detailed solution for the stenosed coronary hemodynamics by coupling computational fluid dynamics (CFD) with the lumped parameter model (LPM) of the cardiovascular system. In this work, we have implemented a simple computational method to compute the FFR. As this method uses only coronary arteries for the CFD model and includes only the LPM of the coronary vascular system, it provides simpler boundary conditions for the coronary geometry and is computationally more efficient than existing approaches. To test the efficacy of this method, we simulated a three-dimensional straight vessel using CFD coupled with the LPM. The computed results were compared with those of the LPM. To validate this method in terms of clinically realistic geometry, a patient-specific model of stenosed coronary arteries was constructed from CT images, and the computed FFR was compared with clinically measured results. We evaluated the effect of a model aorta on the computed FFR and compared this with a model without the aorta. Computationally, the model without the aorta was more efficient than that with the aorta, reducing the CPU time required for computing a cardiac cycle to 43.4%.
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Affiliation(s)
- Soon-Sung Kwon
- Department of Mechanical and Biomedical Engineering, Kangwon National University, 192-1, Hyoja 2-dong, Chuncheon, Kangwon 200-701, Republic of Korea
| | - Eui-Chul Chung
- Department of Mechanical and Biomedical Engineering, Kangwon National University, 192-1, Hyoja 2-dong, Chuncheon, Kangwon 200-701, Republic of Korea
| | - Jin-Seo Park
- Department of Mechanical and Biomedical Engineering, Kangwon National University, 192-1, Hyoja 2-dong, Chuncheon, Kangwon 200-701, Republic of Korea
| | - Gook-Tae Kim
- Department of Mechanical and Biomedical Engineering, Kangwon National University, 192-1, Hyoja 2-dong, Chuncheon, Kangwon 200-701, Republic of Korea
| | - Jun-Woo Kim
- Department of Mechanical and Biomedical Engineering, Kangwon National University, 192-1, Hyoja 2-dong, Chuncheon, Kangwon 200-701, Republic of Korea
| | - Keun-Hong Kim
- Department of Mechanical and Biomedical Engineering, Kangwon National University, 192-1, Hyoja 2-dong, Chuncheon, Kangwon 200-701, Republic of Korea
| | - Eun-Seok Shin
- Division of Cardiology, Department of Internal Medicine, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, Republic of Korea
| | - Eun Bo Shim
- Department of Mechanical and Biomedical Engineering, Kangwon National University, 192-1, Hyoja 2-dong, Chuncheon, Kangwon 200-701, Republic of Korea.
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17
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Min BG. Applications of Artificial Heart Research to the Life-Saving Device. Artif Organs 2013; 37:587-90. [DOI: 10.1111/aor.12095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Byoung Goo Min
- Department of Biomedical Engineering; Seoul National University College of Medicine; Seoul; 110-744; Korea
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Lim KM, Lee JS, Gyeong MS, Choi JS, Choi SW, Shim EB. Computational quantification of the cardiac energy consumption during intra-aortic balloon pumping using a cardiac electromechanics model. J Korean Med Sci 2013; 28:93-9. [PMID: 23341718 PMCID: PMC3546111 DOI: 10.3346/jkms.2013.28.1.93] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2012] [Accepted: 09/09/2012] [Indexed: 11/20/2022] Open
Abstract
To quantify the reduction in workload during intra-aortic balloon pump (IABP) therapy, indirect parameters are used, such as the mean arterial pressure during diastole, product of heart rate and peak systolic pressure, and pressure-volume area. Therefore, we investigated the cardiac energy consumption during IABP therapy using a cardiac electromechanics model. We incorporated an IABP function into a previously developed electromechanical model of the ventricle with a lumped model of the circulatory system and investigated the cardiac energy consumption at different IABP inflation volumes. When the IABP was used at inflation level 5, the cardiac output and stroke volume increased 11%, the ejection fraction increased 21%, the stroke work decreased 1%, the mean arterial pressure increased 10%, and the ATP consumption decreased 12%. These results show that although the ATP consumption is decreased significantly, stroke work is decreased only slightly, which indicates that the IABP helps the failed ventricle to pump blood efficiently.
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Affiliation(s)
- Ki Moo Lim
- Department of Medical IT Convergence Engineering, Kumoh National Institute of Technology, Gumi, Korea
| | - Jeong Sang Lee
- Department of Thoracic and Cardiovascular Surgery, Seoul National University College of Medicine, & SMG-SNU Boramae Hospital, Seoul, Korea
| | - Min-Soo Gyeong
- Department of Mechanical and Biomedical Engineering, Kangwon National University, Chuncheon, Korea
| | - Jae-Sung Choi
- Department of Thoracic and Cardiovascular Surgery, Seoul National University College of Medicine, & SMG-SNU Boramae Hospital, Seoul, Korea
| | - Seong Wook Choi
- Department of Mechanical and Biomedical Engineering, Kangwon National University, Chuncheon, Korea
| | - Eun Bo Shim
- Department of Mechanical and Biomedical Engineering, Kangwon National University, Chuncheon, Korea
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19
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Lim KM, Yang SH, Shim EB. Systemic modelling of human bioenergetics and blood circulation. IET Syst Biol 2012; 6:187-95. [PMID: 23101873 DOI: 10.1049/iet-syb.2011.0035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
This work reviews the main aspects of human bioenergetics and the dynamics of the cardiovascular system, with emphasis on modelling their physiological characteristics. The methods used to study human bioenergetics and circulation dynamics, including the use of mathematical models, are summarised. The main characteristics of human bioenergetics, including mitochondrial metabolism and global energy balance, are first described, and the systemic aspects of blood circulation and related physiological issues are introduced. The authors also discuss the present status of studies of human bioenergetics and blood circulation. Then, the limitations of the existing studies are described in an effort to identify directions for future research towards integrated and comprehensive modelling. This review emphasises that a multi-scale and multi-physical approach to bioenergetics and blood circulation that considers multiple scales and physiological factors are necessary for the appropriate clinical application of computational models.
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Affiliation(s)
- K M Lim
- Department of Medical IT Convergence Engineering, Kumoh Institute of Technology, Daehakro, Kumi, Gyengpook 730-701, Republic of Korea
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20
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Computational Analysis of the Effect of the Control Model of Intraaorta Pump on Ventricular Unloading and Vessel Response. ASAIO J 2012; 58:455-61. [DOI: 10.1097/mat.0b013e31825f3353] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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21
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Lumped parameter model for heart failure with novel regulating mechanisms of peripheral resistance and vascular compliance. ASAIO J 2012; 58:223-31. [PMID: 22395118 DOI: 10.1097/mat.0b013e31824ab695] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
To research the change in the physiological mechanism between the heart failure (HF) patient and healthy persons, the physiology parameters, which include the myocardial contractility, systemic vascular resistance (SVR), and vascular compliance, were studied. Through clinical data of HF patients, the computing method of the myocardial contractility was proposed; SVR as a function with respect to mean arterial pressure (MAP) was represented; and the vascular compliance was defined as a function with respect to MAP and cardiac output. Based on these parameters, a lumped parameter model of the cardiovascular system was established to reproduce the hemodynamic status of HF patients and verify the validity of the physiological mechanism. The simulation results demonstrate that the proportional error of mean flow, arterial pressure, and systolic blood pressure is 11.9%, 2.3%, and 4.7% compared with the clinical data, respectively. The proportional error of end-diastolic volume, end-systolic volume , and ejection fraction is 13.4%, 3%, and 3.9%, respectively.
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22
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Ibrahim M, Rao C, Athanasiou T, Yacoub MH, Terracciano CM. Mechanical unloading and cell therapy have a synergistic role in the recovery and regeneration of the failing heart. Eur J Cardiothorac Surg 2012; 42:312-8. [DOI: 10.1093/ejcts/ezs067] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
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Lim KM, Constantino J, Gurev V, Zhu R, Shim EB, Trayanova NA. Comparison of the effects of continuous and pulsatile left ventricular-assist devices on ventricular unloading using a cardiac electromechanics model. J Physiol Sci 2012; 62:11-9. [PMID: 22076841 PMCID: PMC3313670 DOI: 10.1007/s12576-011-0180-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Accepted: 10/23/2011] [Indexed: 01/24/2023]
Abstract
Left ventricular-assist devices (LVADs) are used to supply blood to the body of patients with heart failure. Pressure unloading is greater for counter-pulsating LVADs than for continuous LVADs. However, several clinical trials have demonstrated that myocardial recovery is similar for both types of LVAD. This study examined the contractile energy consumption of the myocardium with continuous and counter-pulsating LVAD support to ascertain the effect of the different LVADs on myocardial recovery. We used a three-dimensional electromechanical model of canine ventricles, with models of the circulatory system and an LVAD. We compared the left ventricular peak pressure (LVPP) and contractile ATP consumption between pulsatile and continuous LVADs. With the continuous and counter-pulsating LVAD, the LVPP decreased to 46 and 10%, respectively, and contractile ATP consumption decreased to 60 and 50%. The small difference between the contractile ATP consumption of these two types of LVAD may explain the comparable effects of the two types on myocardial recovery.
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Affiliation(s)
- Ki Moo Lim
- Department of Mechanical and Biomedical Engineering, Kangwon National University, Chuncheon, Kangwon-do Republic of Korea
| | - Jason Constantino
- Institute for Computational Medicine and the Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21218 USA
| | - Viatcheslav Gurev
- Institute for Computational Medicine and the Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21218 USA
| | - Renjun Zhu
- Institute for Computational Medicine and the Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21218 USA
| | - Eun Bo Shim
- Department of Mechanical and Biomedical Engineering, Kangwon National University, Chuncheon, Kangwon-do Republic of Korea
| | - Natalia A. Trayanova
- Institute for Computational Medicine and the Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21218 USA
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24
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Lim KM, Lee JS, Song JH, Youn CH, Choi JS, Shim EB. Theoretical estimation of cannulation methods for left ventricular assist device support as a bridge to recovery. J Korean Med Sci 2011; 26:1591-8. [PMID: 22147996 PMCID: PMC3230019 DOI: 10.3346/jkms.2011.26.12.1591] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Accepted: 10/17/2011] [Indexed: 11/30/2022] Open
Abstract
Left ventricular assist device (LVAD) support under cannulation connected from the left atrium to the aorta (LA-AA) is used as a bridge to recovery in heart failure patients because it is non-invasive to ventricular muscle. However, it has serious problems, such as valve stenosis and blood thrombosis due to the low ejection fraction of the ventricle. We theoretically estimated the effect of the in-series cannulation, connected from ascending aorta to descending aorta (AA-DA), on ventricular unloading as an alternative to the LA-AA method. We developed a theoretical model of a LVAD-implanted cardiovascular system that included coronary circulation. Using this model, we compared hemodynamic responses according to various cannulation methods such as LA-AA, AA-DA, and a cannulation connected from the left ventricle to ascending aorta (LV-AA), under continuous and pulsatile LVAD supports. The AA-DA method provided 14% and 18% less left ventricular peak pressure than the LA-AA method under continuous and pulsatile LVAD conditions, respectively. The LA-AA method demonstrated higher coronary flow than AA-DA method. Therefore, the LA-AA method is more advantageous in increasing ventricular unloading whereas the AA-DA method is a better choice to increase coronary perfusion.
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Affiliation(s)
- Ki Moo Lim
- Department of Mechanical & Biomedical Engineering, Kangwon National University, Chucheon, Korea
| | - Jeong Sang Lee
- Department of Thoracic and Cardiovascular Surgery, Seoul National University College of Medicine and SMG-SNU Boramae Hospital, Seoul, Korea
| | - Jin-Ho Song
- Department of Mechanical & Biomedical Engineering, Kangwon National University, Chucheon, Korea
| | - Chan-Hyun Youn
- Department of Information and Communications Engineering, Korea Advanced Institute of Science and Technology, Daejeon, Korea
| | - Jae-Sung Choi
- Department of Thoracic and Cardiovascular Surgery, Seoul National University College of Medicine and SMG-SNU Boramae Hospital, Seoul, Korea
| | - Eun Bo Shim
- Department of Mechanical & Biomedical Engineering, Kangwon National University, Chucheon, Korea
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25
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Abstract
The control of force production in vascular smooth muscle is critical to the normal regulation of blood flow and pressure, and altered regulation is common to diseases such as hypertension, heart failure, and ischemia. A great deal has been learned about imbalances in vasoconstrictor and vasodilator signals, e.g., angiotensin, endothelin, norepinephrine, and nitric oxide, that regulate vascular tone in normal and disease contexts. In contrast there has been limited study of how the phenotypic state of the vascular smooth muscle cell may influence the contractile response to these signaling pathways dependent upon the developmental, tissue-specific (vascular bed) or disease context. Smooth, skeletal, and cardiac muscle lineages are traditionally classified into fast or slow sublineages based on rates of contraction and relaxation, recognizing that this simple dichotomy vastly underrepresents muscle phenotypic diversity. A great deal has been learned about developmental specification of the striated muscle sublineages and their phenotypic interconversions in the mature animal under the control of mechanical load, neural input, and hormones. In contrast there has been relatively limited study of smooth muscle contractile phenotypic diversity. This is surprising given the number of diseases in which smooth muscle contractile dysfunction plays a key role. This review focuses on smooth muscle contractile phenotypic diversity in the vascular system, how it is generated, and how it may determine vascular function in developmental and disease contexts.
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Affiliation(s)
- Steven A Fisher
- Department of Medicine, and Cardiovascular Research Institute, Case Western Reserve University, Cleveland, Ohio 44106-7290, USA.
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