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Ertugrul IA, Puspitarani RADA, Wijntjes B, Vervoorn MT, Ballan EM, van der Kaaij NP, van Goor H, Westenbrink BD, van der Plaats A, Nijhuis F, van Suylen V, Erasmus ME. Ex Situ Left Ventricular Pressure-Volume Loop Analyses for Donor Hearts: Proof of Concept in an Ovine Experimental Model. Transpl Int 2024; 37:12982. [PMID: 39055346 PMCID: PMC11269103 DOI: 10.3389/ti.2024.12982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Accepted: 06/26/2024] [Indexed: 07/27/2024]
Abstract
Ex situ heart perfusion (ESHP) has emerged as an important strategy to preserve donation after brain death (DBD) and donation after circulatory death (DCD) donor hearts. Clinically, both DBD and DCD hearts are successfully preserved using ESHP. Viability assessment is currently based on biochemical values, while a reliable method for graft function assessment in a physiologic working mode is unavailable. As functional assessment during ESHP has demonstrated the highest predictive value of outcome post-transplantation, this is an important area for improvement. In this study, a novel method for ex situ assessment of left ventricular function with pressure-volume loop analyses is evaluated. Ovine hearts were functionally evaluated during normothermic ESHP with the novel pressure-volume loop system. This system provides an afterload and adjustable preload to the left ventricle. By increasing the preload and measuring end-systolic elastance, the system could successfully assess the left ventricular function. End-systolic elastance at 60 min and 120 min was 2.8 ± 1.8 mmHg/mL and 2.7 ± 0.7 mmHg/mL, respectively. In this study we show a novel method for functional graft assessment with ex situ pressure-loop analyses during ESHP. When further validated, this method for pressure-volume assessments, could be used for better graft selection in both DBD and DCD donor hearts.
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Affiliation(s)
- I. A. Ertugrul
- Department of Cardiothoracic Surgery, University Medical Centre Groningen, University of Groningen, Groningen, Netherlands
| | - R. A. D. A. Puspitarani
- Department of Cardiology, University Medical Centre Groningen, University of Groningen, Groningen, Netherlands
| | | | - M. T. Vervoorn
- Department of Cardiothoracic Surgery, University Medical Centre Utrecht, Utrecht, Netherlands
| | - E. M. Ballan
- Department of Cardiothoracic Surgery, University Medical Centre Utrecht, Utrecht, Netherlands
- Department of Cardiology, Laboratory of Experimental Cardiology, University Medical Center Utrecht, Utrecht, Netherlands
- Netherlands Heart Institute, Utrecht, Netherlands
| | - N. P. van der Kaaij
- Department of Cardiothoracic Surgery, University Medical Centre Utrecht, Utrecht, Netherlands
| | - H. van Goor
- Department of Medical Biology and Pathology, University Medical Centre Groningen, University of Groningen, Groningen, Netherlands
| | - B. D. Westenbrink
- Department of Cardiology, University Medical Centre Groningen, University of Groningen, Groningen, Netherlands
| | | | | | - V. van Suylen
- Department of Cardiothoracic Surgery, University Medical Centre Groningen, University of Groningen, Groningen, Netherlands
| | - M. E. Erasmus
- Department of Cardiothoracic Surgery, University Medical Centre Groningen, University of Groningen, Groningen, Netherlands
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Pigot H, Soltesz K, Steen S. Ex Vivo Working Porcine Heart Model. Methods Mol Biol 2024; 2803:87-107. [PMID: 38676887 DOI: 10.1007/978-1-0716-3846-0_7] [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: 04/29/2024]
Abstract
Ex vivo working porcine heart models allow for the study of a heart's function and physiology outside the living organism. These models are particularly useful due to the anatomical and physiological similarities between porcine and human hearts, providing an experimental platform to investigate cardiac disease or assess donor heart viability for transplantation. This chapter presents an in-depth discussion of the model's components, including the perfusate, preload, and afterload. We explore the challenges of emulating cardiac afterload and present a historical perspective on afterload modeling, discussing various methodologies and their respective limitations. An actively controlled afterload device is introduced to enhance the model's ability to rapidly adjust pressure in the large arteries, thereby providing a more accurate and dynamic experimental model. Finally, we provide a comprehensive experimental protocol for the ex vivo working porcine heart model.
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Affiliation(s)
- Henry Pigot
- Department of Automatic Control, Lund University, Lund, Sweden.
| | | | - Stig Steen
- Department of Cardiothoracic Surgery, Skåne University Hospital, Lund, Sweden
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3
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Umo A, Kung EO. A Protocol for Coupling Volumetrically Dynamic In-Vitro Experiments to Numerical Physiology Simulation for a Hybrid Cardiovascular Model. IEEE Trans Biomed Eng 2023; 70:1351-1358. [PMID: 36269903 PMCID: PMC11232494 DOI: 10.1109/tbme.2022.3216542] [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: 11/06/2022]
Abstract
OBJECTIVE The Physiology Simulation Coupled Experiment (PSCOPE) is a hybrid modeling framework that enables a physical fluid experiment to operate in the context of a closed-loop computational simulation of cardiovascular physiology. Previous PSCOPE methods coupled rigid experiments to a lumped parameter network (LPN) of physiology but are incompatible with volumetrically dynamic experiments where fluid volume varies periodically. We address this limitation by introducing a method capable of coupling multi-branch and volumetrically dynamic in-vitro experiments to an LPN. METHODS Our proposed method utilizes an iterative weighted-averaging algorithm to identify the unique solution waveforms for a given PSCOPE model. We confirm the accuracy of these PSCOPE solutions by integrating mathematical surrogates of in-vitro experiments directly into the LPN to derive reference solutions, which serve as the gold standard to validate the solutions obtained from using our proposed method to couple the same mathematical surrogates to the LPN. Finally, we illustrate a practical application of our PSCOPE method by coupling an in-vitro renal circulation experiment to the LPN. RESULTS Compared to the reference solution, the normalized root mean square error of the flow and pressure waveforms were 0.001%∼0.55%, demonstrating the accuracy of the coupling method. CONCLUSION We successfully coupled the in-vitro experiment to the LPN, demonstrating the real-world performance within the constraints of sensor and actuation limitations in the physical experiment. SIGNIFICANCE This study introduces a PSCOPE method that can be used to investigate medical devices and anatomies that exhibit periodic volume changes, expanding the utility of the hybrid framework.
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Karageorgos GM, Kemper P, Lee C, Weber R, Kwon N, Meshram N, Mobadersany N, Grondin J, Marshall RS, Miller EC, Konofagou EE. Adaptive Wall Shear Stress Imaging in Phantoms, Simulations and In Vivo. IEEE Trans Biomed Eng 2023; 70:154-165. [PMID: 35776824 PMCID: PMC10103592 DOI: 10.1109/tbme.2022.3186854] [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] [Indexed: 11/10/2022]
Abstract
WSS measurement is challenging since it requires sensitive flow measurements at a distance close to the wall. The aim of this study is to develop an ultrasound imaging technique which combines vector flow imaging with an unsupervised data clustering approach that automatically detects the region close to the wall with optimally linear flow profile, to provide direct and robust WSS estimation. The proposed technique was evaluated in phantoms, mimicking normal and atherosclerotic vessels, and spatially registered Fluid Structure Interaction (FSI) simulations. A relative error of 6.7% and 19.8% was obtained for peak systolic (WSSPS) and end diastolic (WSSED) WSS in the straight phantom, while in the stenotic phantom, a good similarity was found between measured and simulated WSS distribution, with a correlation coefficient, R, of 0.89 and 0.85 for WSSPS and WSSED, respectively. Moreover, the feasibility of the technique to detect pre-clinical atherosclerosis was tested in an atherosclerotic swine model. Six swines were fed atherogenic diet, while their left carotid artery was ligated in order to disturb flow patterns. Ligated arterial segments that were exposed to low WSSPS and WSS characterized by high frequency oscillations at baseline, developed either moderately or highly stenotic plaques (p < 0.05). Finally, feasibility of the technique was demonstrated in normal and atherosclerotic human subjects. Atherosclerotic carotid arteries with low stenosis had lower WSSPS as compared to control subjects (p < 0.01), while in one subject with high stenosis, elevated WSS was found on an arterial segment, which coincided with plaque rupture site, as determined through histological examination.
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Guest B, Arroyo L, Runciman J. A structural approach to 3D-printing arterial phantoms with physiologically comparable mechanical characteristics: Preliminary observations. Proc Inst Mech Eng H 2022; 236:1388-1402. [PMID: 35913071 PMCID: PMC9449448 DOI: 10.1177/09544119221114207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Pulse wave behavior is important in cardiovascular pathophysiology and arterial
phantoms are valuable for studying arterial function. The ability of phantoms to
replicate complex arterial elasticity and anatomy is limited by available
materials and techniques. The feasibility of improving phantom performance using
functional structure designs producible with practical 3D printing technologies
was investigated. A novel corrugated wall approach to separate phantom function
from material properties was investigated with a series of designs printed from
polyester-polyurethane using a low-cost open-source fused filament fabrication
3D printer. Nonpulsatile pressure-diameter data was collected, and a mock
circulatory system was used to observe phantom pulse wave behavior and obtain
pulse wave velocities. The measured range of nonpulsatile Peterson elastic
strain modulus was 5.6–19 to 12.4–33.0 kPa over pressures of 5–35 mmHg for the
most to least compliant designs respectively. Pulse wave velocities of
1.5–5 m s−1 over mean pressures of 7–55 mmHg were observed,
comparing favorably to reported in vivo pulmonary artery measurements of
1–4 m s−1 across mammals. Phantoms stiffened with increasing
pressure in a manner consistent with arteries, and phantom wall elasticity
appeared to vary between designs. Using a functional structure approach,
practical low-cost 3D-printed production of simple arterial phantoms with
mechanical properties that closely match the pulmonary artery is possible.
Further functional structure design development to expand the pressure range and
physiologic utility of dir"ectly 3D-printed phantoms appears warranted.
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Affiliation(s)
- Bruce Guest
- School of Engineering, University of Guelph, Guelph, ON, Canada
- Ontario Veterinary College Health Sciences Centre, University of Guelph, Guelph, ON, Canada
| | - Luis Arroyo
- Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada
| | - John Runciman
- School of Engineering, University of Guelph, Guelph, ON, Canada
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Yu H, Khan M, Wu H, Du X, Chen R, Rollins DM, Fang X, Long J, Xu C, Sawchuk AP. A new noninvasive and patient-specific hemodynamic index for the severity of renal stenosis and outcome of interventional treatment. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2022; 38:e3611. [PMID: 35509229 PMCID: PMC9539998 DOI: 10.1002/cnm.3611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 12/30/2021] [Accepted: 04/29/2022] [Indexed: 06/14/2023]
Abstract
Renal arterial stenosis (RAS) often causes renovascular hypertension, which may result in kidney failure and life-threatening consequences. Direct assessment of the hemodynamic severity of RAS has yet to be addressed. In this work, we present a computational concept to derive a new, noninvasive, and patient-specific index to assess the hemodynamic severity of RAS and predict the potential benefit to the patient from a stenting therapy. The hemodynamic index is derived from a functional relation between the translesional pressure indicator (TPI) and lumen volume reduction (S) through a parametric deterioration of the RAS. Our in-house computational platform, InVascular, for image-based computational hemodynamics is used to compute the TPI at given S. InVascular integrates unified computational modeling for both image processing and computational hemodynamics with graphic processing unit parallel computing technology. The TPI-S curve reveals a pair of thresholds of S indicating mild or severe RAS. The TPI at S = 0 represents the pressure improvement following a successful stenting therapy. Six patient cases with a total of 6 aortic and 12 renal arteries are studied. The computed blood pressure waveforms have good agreements with the in vivo measured ones and the systolic pressure is statistical equivalence to the in-vivo measurements with p < .001. Uncertainty quantification provides the reliability of the computed pressure through the corresponding 95% confidence interval. The severity assessments of RAS in four cases are consistent with the medical practice. The preliminary results inspire a more sophisticated investigation for real medical insights of the new index. This computational concept can be applied to other arterial stenoses such as iliac stenosis. Such a noninvasive and patient-specific hemodynamic index has the potential to aid in the clinical decision-making of interventional treatment with reduced medical cost and patient risks.
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Affiliation(s)
- Huidan Yu
- Department of Mechanical and Energy EngineeringIndiana University‐Purdue University, Indianapolis (IUPUI)IndianapolisIndianaUSA
- Department of SurgeryIndiana University School of MedicineIndianapolisIndianaUSA
| | - Monsurul Khan
- Department of Mechanical and Energy EngineeringIndiana University‐Purdue University, Indianapolis (IUPUI)IndianapolisIndianaUSA
- Present address:
School of Mechanical EngineeringPurdue UniversityWest LafayetteIndianaUSA
| | - Hao Wu
- Department of Mechanical and Energy EngineeringIndiana University‐Purdue University, Indianapolis (IUPUI)IndianapolisIndianaUSA
| | - Xiaoping Du
- Department of Mechanical and Energy EngineeringIndiana University‐Purdue University, Indianapolis (IUPUI)IndianapolisIndianaUSA
| | - Rou Chen
- Department of Mechanical and Energy EngineeringIndiana University‐Purdue University, Indianapolis (IUPUI)IndianapolisIndianaUSA
- Present address:
College of Metrology and Measurement EngineeringChina Jiliang UniversityHangzhouChina
| | - Dave M. Rollins
- Vascular Diagnostic CenterIndiana University HealthIndianapolisIndianaUSA
| | - Xin Fang
- Department of Vascular Surgery, The Affiliated Hangzhou First People's HospitalZhejiang University School of MedicineHangzhouChina
| | - Jianyun Long
- Department of Vascular Surgery, The Affiliated Hangzhou First People's HospitalZhejiang University School of MedicineHangzhouChina
| | - Chenke Xu
- Department of Ultrasound, The Affiliated Hangzhou First People's HospitalZhejiang University School of MedicineHangzhouChina
| | - Alan P. Sawchuk
- Department of SurgeryIndiana University School of MedicineIndianapolisIndianaUSA
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7
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Pigot H, Soltesz K, Paskevicius A, Liao Q, Sjöberg T, Steen S. A novel nonlinear afterload for ex vivo heart evaluation: porcine experimental results. Artif Organs 2022; 46:1794-1803. [PMID: 35548921 PMCID: PMC9545718 DOI: 10.1111/aor.14307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 04/13/2022] [Accepted: 04/29/2022] [Indexed: 11/28/2022]
Abstract
Background Existing working heart models for ex vivo functional evaluation of donor hearts often use cardiac afterloads made up of discrete resistive and compliant elements. This approach limits the practicality of independently controlling systolic and diastolic aortic pressure to safely test the heart under multiple loading conditions. We present and investigate a novel afterload concept designed to enable such control. Methods Six ∼70 kg pig hearts were evaluated in vivo, then ex vivo in left‐ventricular working mode using the presented afterload. Both in vivo and ex vivo, the hearts were evaluated at two exertion levels: at rest and following a 20 μg adrenaline bolus, while measuring aortic pressure and flow, left ventricular pressure and volume, and left atrial pressure. Results The afterload gave aortic pressure waveforms that matched the general shape of the in vivo measurements. A wide range of physiological systolic pressures (93 to 160 mm Hg) and diastolic pressures (73 to 113 mm Hg) were generated by the afterload. Conclusions With the presented afterload concept, multiple physiological loading conditions could be tested ex vivo, and compared with the corresponding in vivo data. An additional control loop from the set pressure limits to the measured systolic and diastolic aortic pressure is proposed to address discrepancies observed between the set limits and the measured pressures.
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Affiliation(s)
- Henry Pigot
- Lund University, Dept Automatic Control, Sweden
| | | | - Audrius Paskevicius
- Lund University, Div. Thoracic Surgery, Dept. Clinical Sciences and Skane° University Hospital, Dept. Cardiothoracic Surgery, Sweden
| | - Qiuming Liao
- Lund University, Div. Thoracic Surgery, Dept. Clinical Sciences and Skane° University Hospital, Dept. Cardiothoracic Surgery, Sweden
| | - Trygve Sjöberg
- Lund University, Div. Thoracic Surgery, Dept. Clinical Sciences and Skane° University Hospital, Dept. Cardiothoracic Surgery, Sweden
| | - Stig Steen
- Lund University, Div. Thoracic Surgery, Dept. Clinical Sciences and Skane° University Hospital, Dept. Cardiothoracic Surgery, Sweden
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8
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Moravia A, Simoëns S, El Hajem M, Bou-Saïd B, Kulisa P, Della-Schiava N, Lermusiaux P. In vitro flow study in a compliant abdominal aorta phantom with a non-Newtonian blood-mimicking fluid. J Biomech 2021; 130:110899. [PMID: 34923186 DOI: 10.1016/j.jbiomech.2021.110899] [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] [Received: 05/28/2021] [Revised: 12/02/2021] [Accepted: 12/02/2021] [Indexed: 10/19/2022]
Abstract
In vitro aortic flow simulators allow studying hemodynamics with a wider range of flow visualization techniques compared to in vivo medical imaging and without the limitations of invasive examinations. This work aims to develop an experimental bench to emulate the pulsatile circulation in a realistic aortic phantom. To mimic the blood shear thinning behavior, a non-Newtonian aqueous solution is prepared with glycerin and xanthan gum polymer. The flow is compared to a reference flow of Newtonian fluid. Particle image velocimetry is carried out to visualize 2D velocity fields in a phantom section. The experimental loop accurately recreates flowrates and pressure conditions and preserves the shear-thinning properties of the non-Newtonian fluid. Velocity profiles, shear rate, and shear stress distribution maps show that the Newtonian fluid tends to dampen the observed velocities. Preferential asymmetrical flow paths are observed in a diameter narrowing region and amplified in the non-Newtonian case. Wall shear stresses are about twice higher in the non-Newtonian case. This study shows new insights on flow patterns, velocity and shear stress distributions compared to rigid and simplified geometry aorta phantom with Newtonian fluid flows studies. The use of a non-Newtonian blood analog shows clear differences in flows compared to the Newtonian one in this compliant patient-specific geometry. The development of this aortic simulator is a promising tool to better analyze and understand aortic hemodynamics and to aid in clinical decision-making.
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Affiliation(s)
- Anaïs Moravia
- Université de Lyon, INSA de Lyon, Ecole Centrale de Lyon, Université Claude Bernard Lyon 1, CNRS, LMFA UMR 5509, Villeurbanne, France.
| | - Serge Simoëns
- Université de Lyon, INSA de Lyon, Ecole Centrale de Lyon, Université Claude Bernard Lyon 1, CNRS, LMFA UMR 5509, Villeurbanne, France
| | - Mahmoud El Hajem
- Université de Lyon, INSA de Lyon, Ecole Centrale de Lyon, Université Claude Bernard Lyon 1, CNRS, LMFA UMR 5509, Villeurbanne, France
| | - Benyebka Bou-Saïd
- Université de Lyon, CNRS, INSA de Lyon, LaMCoS UMR5259, Villeurbanne, France
| | - Pascale Kulisa
- Université de Lyon, INSA de Lyon, Ecole Centrale de Lyon, Université Claude Bernard Lyon 1, CNRS, LMFA UMR 5509, Villeurbanne, France
| | | | - Patrick Lermusiaux
- Vascular and Endovascular Department, Hospices Civils de Lyon, Lyon, France
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Hondjeu ARM, Mashari A, Ramos R, Ruggeri GM, Gellner B, Ribeiro RVP, Hiansen JQ, Yu F, Xin L, Adamson MB, Badiwala MV, Meineri M. Echocardiographic assessment of left ventricular function in ex situ heart perfusion using pump-supported and passive afterload working mode: a pilot study. JOURNAL OF ANESTHESIA, ANALGESIA AND CRITICAL CARE (ONLINE) 2021; 1:20. [PMID: 37386658 DOI: 10.1186/s44158-021-00018-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 10/29/2021] [Indexed: 07/01/2023]
Abstract
Ex situ heart perfusion (ESHP) has been developed to decrease cold ischemia time and allow metabolic assessment of donor hearts prior to transplantation. Current clinical ESHP systems preserve the heart in an unloaded condition and only evaluate the cardiac metabolic profile. In this pilot study we performed echocardiographic functional assessment using two alternative systems for left ventricular (LV) loading: pump supported afterload working mode (SAM) and passive afterload working modes (PAM). Six hearts were procured from male Yorkshire pigs. During cold ischemia, hearts were mounted on our custom made ESHP circuit and a 3D-printed enclosure for the performance of echocardiography with a standard TEE probe. Following perfusion with Langherdorf mode of the unloaded heart, the system was switched into different working modes to allow LV loading and functional assessment: pump supported (SAM) and passive (PAM). Echocardiographic assessment of left ventricular function in the donor hearts was performed in vivo and at 1 h of ESHP with SAM, after 4.5 h with PAM and after 5.5 h with SAM. We obtained good quality epicardial echocardiographic images at all time points allowing a comprehensive LV systolic assessment. All indices showed a decrease in LV systolic function throughout the trial with the biggest drop after heart harvesting. We demonstrated the feasibility of echocardiographic functional assessment during ESHP and two different working modes. The expected LV systolic dysfunction consisted of a reduction in EF, FAC, FS, and strain throughout the experiment with the most significant decrease after harvesting.
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Affiliation(s)
- Arnaud Romeo Mbadjeu Hondjeu
- Department of Anesthesia and Pain Management, Peter Munk Cardiac Center Toronto General Hospital, University Health Network, Toronto, Canada
| | - Azad Mashari
- Department of Anesthesia and Pain Management, Peter Munk Cardiac Center Toronto General Hospital, University Health Network, Toronto, Canada
| | - Ryan Ramos
- Department of Anesthesia and Pain Management, Peter Munk Cardiac Center Toronto General Hospital, University Health Network, Toronto, Canada
| | - Giulia Maria Ruggeri
- Department of Anesthesia and Pain Management, Peter Munk Cardiac Center Toronto General Hospital, University Health Network, Toronto, Canada
| | - Bryan Gellner
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Canada
| | - Roberto Vanin Pinto Ribeiro
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Canada
- Division of Cardiovascular Surgery, Peter Munk Cardiac Center, Toronto General Hospital, University Health Network, Toronto, Canada
| | - Joshua Qua Hiansen
- Department of Anesthesia and Pain Management, Peter Munk Cardiac Center Toronto General Hospital, University Health Network, Toronto, Canada
| | - Frank Yu
- Division of Cardiovascular Surgery, Peter Munk Cardiac Center, Toronto General Hospital, University Health Network, Toronto, Canada
| | - Liming Xin
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Canada
- Division of Cardiovascular Surgery, Peter Munk Cardiac Center, Toronto General Hospital, University Health Network, Toronto, Canada
| | - Mitchell Brady Adamson
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Canada
- Division of Cardiovascular Surgery, Peter Munk Cardiac Center, Toronto General Hospital, University Health Network, Toronto, Canada
| | - Mitesh Vallabh Badiwala
- Division of Cardiovascular Surgery, Peter Munk Cardiac Center, Toronto General Hospital, University Health Network, Toronto, Canada
- Department of Surgery, Faculty of Medicine, University of Toronto, Toronto, Canada
| | - Massimiliano Meineri
- Department of Anesthesia and Pain Management, Peter Munk Cardiac Center Toronto General Hospital, University Health Network, Toronto, Canada.
- Department of Anesthesia and Intensive Care, Herzzentrum Leipzig, Strumpell Strasse 39, 04289, Leipzig, Germany.
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Karageorgos GM, Apostolakis IZ, Nauleau P, Gatti V, Weber R, Kemper P, Konofagou EE. Pulse Wave Imaging Coupled With Vector Flow Mapping: A Phantom, Simulation, and In Vivo Study. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2021; 68:2516-2531. [PMID: 33950838 PMCID: PMC8477914 DOI: 10.1109/tuffc.2021.3074113] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Pulse wave imaging (PWI) is an ultrasound imaging modality that estimates the wall stiffness of an imaged arterial segment by tracking the pulse wave propagation. The aim of the present study is to integrate PWI with vector flow imaging, enabling simultaneous and co-localized mapping of vessel wall mechanical properties and 2-D flow patterns. Two vector flow imaging techniques were implemented using the PWI acquisition sequence: 1) multiangle vector Doppler and 2) a cross-correlation-based vector flow imaging (CC VFI) method. The two vector flow imaging techniques were evaluated in vitro using a vessel phantom with an embedded plaque, along with spatially registered fluid structure interaction (FSI) simulations with the same geometry and inlet flow as the phantom setup. The flow magnitude and vector direction obtained through simulations and phantom experiments were compared in a prestenotic and stenotic segment of the phantom and at five different time frames. In most comparisons, CC VFI provided significantly lower bias or precision than the vector Doppler method ( ) indicating better performance. In addition, the proposed technique was applied to the carotid arteries of nonatherosclerotic subjects of different ages to investigate the relationship between PWI-derived compliance of the arterial wall and flow velocity in vivo. Spearman's rank-order test revealed positive correlation between compliance and peak flow velocity magnitude ( rs = 0.90 and ), while significantly lower compliance ( ) and lower peak flow velocity magnitude ( ) were determined in older (54-73 y.o.) compared with young (24-32 y.o.) subjects. Finally, initial feasibility was shown in an atherosclerotic common carotid artery in vivo. The proposed imaging modality successfully provided information on blood flow patterns and arterial wall stiffness and is expected to provide additional insight in studying carotid artery biomechanics, as well as aid in carotid artery disease diagnosis and monitoring.
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Thirugnanasambandam M, Canchi T, Piskin S, Karmonik C, Kung E, Menon PG, Avril S, Finol EA. Design, Development, and Temporal Evaluation of a Magnetic Resonance Imaging-Compatible In Vitro Circulation Model Using a Compliant Abdominal Aortic Aneurysm Phantom. J Biomech Eng 2021; 143:051004. [PMID: 33493273 PMCID: PMC8086180 DOI: 10.1115/1.4049894] [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] [Received: 06/23/2020] [Revised: 01/05/2021] [Indexed: 11/08/2022]
Abstract
Biomechanical characterization of abdominal aortic aneurysms (AAAs) has become commonplace in rupture risk assessment studies. However, its translation to the clinic has been greatly limited due to the complexity associated with its tools and their implementation. The unattainability of patient-specific tissue properties leads to the use of generalized population-averaged material models in finite element analyses, which adds a degree of uncertainty to the wall mechanics quantification. In addition, computational fluid dynamics modeling of AAA typically lacks the patient-specific inflow and outflow boundary conditions that should be obtained by nonstandard of care clinical imaging. An alternative approach for analyzing AAA flow and sac volume changes is to conduct in vitro experiments in a controlled laboratory environment. In this study, we designed, built, and characterized quantitatively a benchtop flow loop using a deformable AAA silicone phantom representative of a patient-specific geometry. The impedance modules, which are essential components of the flow loop, were fine-tuned to ensure typical intraluminal pressure conditions within the AAA sac. The phantom was imaged with a magnetic resonance imaging (MRI) scanner to acquire time-resolved images of the moving wall and the velocity field inside the sac. Temporal AAA sac volume changes lead to a corresponding variation in compliance throughout the cardiac cycle. The primary outcome of this work was the design optimization of the impedance elements, the quantitative characterization of the resistive and capacitive attributes of a compliant AAA phantom, and the exemplary use of MRI for flow visualization and quantification of the deformed AAA geometry.
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Affiliation(s)
- Mirunalini Thirugnanasambandam
- University of Texas at San Antonio, UTSA/UTHSCSA Joint Graduate Program in Biomedical Engineering, San Antonio, TX 78249
| | - Tejas Canchi
- Department of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798
| | - Senol Piskin
- Department of Mechanical Engineering, University of Texas at San Antonio, San Antonio, TX 78249; Department of Mechanical Engineering, Istinye University, Istanbul 34010, Turkey
| | | | - Ethan Kung
- Department of Mechanical Engineering, Clemson UniversityClemson, SC 29634
| | - Prahlad G. Menon
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15260
| | - Stephane Avril
- Ecole Nationale Supérieure des Mines, Center for Biomedical and Healthcare Engineering, St-Etienne 75006, France
| | - Ender A. Finol
- University of Texas at San Antonio, UTSA/UTHSCSA Joint Graduate Program in Biomedical Engineering, San Antonio, TX 78249; Department of Mechanical Engineering, University of Texas at San Antonio, Room EB 3.04.08 One UTSA Circle, San Antonio, TX 78249
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Real-time flow impedance evaluation method for ultra-fast early detection of aneurysmal diseases. Biomed Signal Process Control 2021. [DOI: 10.1016/j.bspc.2020.102256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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13
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Gellner B, Xin L, Ribeiro RVP, Bissoondath V, Lu P, Adamson MB, Yu F, Paradiso E, Zu J, Simmons CA, Badiwala MV. The Implementation of an Adjustable Afterload Module for Ex Situ Heart Perfusion. Cardiovasc Eng Technol 2019; 11:96-110. [PMID: 31797263 DOI: 10.1007/s13239-019-00447-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Accepted: 11/24/2019] [Indexed: 12/23/2022]
Abstract
PURPOSE Windkessel impedance analysis has proven to be an effective technique for instituting artificial afterload on ex situ hearts. Traditional fixed parameter afterload modules, however, are unable to handle the changing contractile conditions associated with prolonged ex situ heart perfusion. In this paper, an adjustable afterload module is described comprising of three fully adjustable sub-components: a systemic resistor, a proximal resistor and a compliance chamber. METHODS Using a centrifugal pump, the systemic resistor and compliance chamber were subjected to testing across their operating ranges, whereby the predictability of resistance and compliance values was evaluated. The components were then assembled, and the full module tested on three separate porcine hearts perfused for 6 h with success defined by the ability to maintain physiological systolic and diastolic aortic pressures across flow rate variability. RESULTS For both the systemic resistor and compliance chamber, experimental measurements agreed with their theoretical equivalents, with coefficients of determination of 0.99 and 0.97 for the systemic resistor and compliance chamber, respectively. During ex situ perfusion, overall 95% confidence intervals demonstrate that physiological systolic (95-96.21 mmHg) and diastolic (26.8-28.8 mmHg) pressures were successfully maintained, despite large variability in aortic flow. Left ventricular contractile parameters, were found to be in line with those in previous studies, suggesting the afterload module has no detrimental impact on functional preservation. CONCLUSIONS We conclude that due to the demonstrable control of our afterload module, we can maintain physiological aortic pressures in a passive afterload working mode across prolonged perfusion periods, enabling effective perfusion regardless of contractile performance.
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Affiliation(s)
- Bryan Gellner
- Department of Mechanical & Industrial Engineering, University of Toronto, Toronto, ON, Canada
- Translational Biology & Engineering Program, Ted Rogers Centre for Heart Research, Toronto, ON, Canada
| | - Liming Xin
- Department of Mechanical & Industrial Engineering, University of Toronto, Toronto, ON, Canada
- Division of Cardiovascular Surgery, Toronto General Hospital, University Health Network, Toronto, ON, Canada
- State Key Laboratory of Mechanical Transmissions, Chongqing University, Chongqing, China
| | - Roberto Vanin Pinto Ribeiro
- Division of Cardiovascular Surgery, Toronto General Hospital, University Health Network, Toronto, ON, Canada
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - Ved Bissoondath
- Division of Cardiovascular Surgery, Toronto General Hospital, University Health Network, Toronto, ON, Canada
| | - Pengzhou Lu
- Department of Mechanical & Industrial Engineering, University of Toronto, Toronto, ON, Canada
- Division of Cardiovascular Surgery, Toronto General Hospital, University Health Network, Toronto, ON, Canada
| | - Mitchell B Adamson
- Division of Cardiovascular Surgery, Toronto General Hospital, University Health Network, Toronto, ON, Canada
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - Frank Yu
- Division of Cardiovascular Surgery, Toronto General Hospital, University Health Network, Toronto, ON, Canada
| | - Emanuela Paradiso
- Department of Anesthesia and Pain Management, Toronto General Hospital, University Health Network, Toronto, ON, Canada
| | - Jean Zu
- Department of Mechanical & Industrial Engineering, University of Toronto, Toronto, ON, Canada
| | - Craig A Simmons
- Department of Mechanical & Industrial Engineering, University of Toronto, Toronto, ON, Canada.
- Translational Biology & Engineering Program, Ted Rogers Centre for Heart Research, Toronto, ON, Canada.
- Institute of Biomaterials & Biomedical Engineering, University of Toronto, Toronto, ON, Canada.
| | - Mitesh V Badiwala
- Division of Cardiovascular Surgery, Toronto General Hospital, University Health Network, Toronto, ON, Canada
- Department of Surgery, University of Toronto, Toronto, ON, Canada
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14
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Gellner B, Xin L, Pinto Ribeiro RV, Bissoondath V, Adamson MB, Yu F, Lu P, Paradiso E, Mbadjeu Hondjeu AR, Simmons CA, Badiwala MV. The implementation of physiological afterload during ex situ heart perfusion augments prediction of posttransplant function. Am J Physiol Heart Circ Physiol 2019; 318:H25-H33. [PMID: 31774696 DOI: 10.1152/ajpheart.00427.2019] [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: 11/22/2022]
Abstract
Ex situ heart perfusion (ex situ heart perfusion) is an emerging technique that aims to increase the number of organs available for transplantation by augmenting both donor heart preservation and evaluation. Traditionally, ex situ heart perfusion has been performed in an unloaded Langendorff mode, though more recently groups have begun to use pump-supported working mode (PSWM) and passive afterload working mode (PAWM) to enable contractile evaluation during ex situ heart perfusion. To this point, however, neither the predictive effectiveness of the two working modes nor the predictive power of individual contractile parameters has been analyzed. In this article, we use our previously described system to analyze the predictive relevance of a multitude of contractile parameters measured in each working mode. Ten porcine hearts were excised and perfused ex situ in Langendorff mode for 4 h, evaluated using pressure-volume catheterization in both PSWM and PAWM, and transplanted into size-matched recipient pigs. After 3 h, hearts were weaned from cardiopulmonary bypass and evaluated. When correlating posttransplant measurements to their ex situ counterparts, we report that parameters measured in both modes show sufficient power (Spearman rank coefficient > 0.7) in predicting global posttransplant function, characterized by cardiac index and preload recruitable stroke work. For the prediction of specific posttransplant systolic and diastolic function, however, a large discrepancy between the two working modes was observed. With 9 of 10 measured posttransplant parameters showing stronger correlation with counterparts measured in PAWM, it is concluded that PAWM allows for a more detailed and nuanced prediction of posttransplant function than can be made in PSWM.NEW & NOTEWORTHY Ex situ heart perfusion has been proposed as a means to augment the organ donor pool by improving organ preservation and evaluation between donation and transplantation. Using our multimodal perfusion system, we analyzed the impact of using a "passive afterload working mode" for functional evaluation as compared with the more traditional "pump-supported working mode." Our data suggests that passive afterload working mode allows for a more nuanced prediction of posttransplant function in porcine hearts.
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Affiliation(s)
- Bryan Gellner
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario, Canada.,Translational Biology and Engineering Program, Ted Rogers Centre for Heart Research, Toronto, Ontario, Canada
| | - Liming Xin
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario, Canada.,Division of Cardiovascular Surgery, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada
| | - Roberto Vanin Pinto Ribeiro
- Division of Cardiovascular Surgery, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada.,Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
| | - Ved Bissoondath
- Division of Cardiovascular Surgery, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada
| | - Mitchell B Adamson
- Division of Cardiovascular Surgery, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada.,Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
| | - Frank Yu
- Division of Cardiovascular Surgery, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada
| | - Pengzhou Lu
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario, Canada.,Division of Cardiovascular Surgery, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada
| | - Emanuela Paradiso
- Department of Anesthesia and Pain Management, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada
| | - Arnaud Romeo Mbadjeu Hondjeu
- Department of Anesthesia and Pain Management, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada
| | - Craig A Simmons
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario, Canada.,Translational Biology and Engineering Program, Ted Rogers Centre for Heart Research, Toronto, Ontario, Canada.,Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
| | - Mitesh V Badiwala
- Division of Cardiovascular Surgery, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada.,Department of Surgery, University of Toronto, Toronto, Ontario, Canada
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15
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Computing the ankle-brachial index with parallel computational fluid dynamics. J Biomech 2018; 82:28-37. [PMID: 30385003 DOI: 10.1016/j.jbiomech.2018.10.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 10/09/2018] [Accepted: 10/10/2018] [Indexed: 01/16/2023]
Abstract
The ankle-brachial index (ABI), a ratio of arterial blood pressure in the ankles and upper arms, is used to diagnose and monitor circulatory conditions such as coarctation of the aorta and peripheral artery disease. Computational simulations of the ABI can potentially determine the parameters that produce an ABI indicative of ischemia or other abnormalities in blood flow. However, 0- and 1-D computational methods are limited in describing a 3-D patient-derived geometry. Thus, we present a massively parallel framework for computational fluid dynamics (CFD) simulations in the full arterial system. Using the lattice Boltzmann method to solve the Navier-Stokes equations, we employ highly parallelized and scalable methods to generate the simulation domain and efficiently distribute the computational load among processors. For the first time, we compute an ABI with 3-D CFD. In this proof-of-concept study, we investigate the dependence of ABI on the presence of stenoses, or narrowed regions of the arteries, by directly modifying the arterial geometry. As a result, our framework enables the computation a hemodynamic factor characterizing flow at the scale of the full arterial system, in a manner that is extensible to patient-specific imaging data and holds potential for treatment planning.
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16
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Prim DA, Potts JD, Eberth JF. Pulsatile Perfusion Bioreactor for Biomimetic Vascular Impedances. J Med Device 2018. [DOI: 10.1115/1.4040648] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Pulsatile waves of blood pressure and flow are continuously augmented by the resistance, compliance, and inertance properties of the vasculature, resulting in unique wave characteristics at distinct anatomical locations. Hemodynamically generated loads, transduced as physical signals into resident vascular cells, are crucial to the maintenance and preservation of a healthy vascular physiology; thus, failure to recreate biomimetic loading in vitro can lead to pathological gene expression and aberrant remodeling. As a generalized approach to improve native and engineered blood vessels, we have designed, built, and tested a pulsatile perfusion bioreactor based on biomimetic impedances and a novel five-element electrohydraulic analog. Here, the elements of an incubator-based culture system were formulaically designed to match the vascular impedance of a brachial artery by incorporating both the inherent (systemic) and added elements of the physical system into the theoretical approach. Freshly harvested porcine saphenous veins were perfused within a physiological culture chamber for 6 h and the relative expression of seven known mechanically sensitive remodeling genes analyzed using the quantitative polymerase chain reaction (qPCR) method. Of these, we found plasminogen activator inhibitor-1 (SERPINE1) and fibronectin-1 (FN1) to be highly sensitive to differences between arterial- and venous-like culture conditions. The analytical approach and biological confirmation provide a framework toward the general design of long-term hemodynamic-mimetic vascular culture systems.
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Affiliation(s)
- David A. Prim
- College of Engineering and Computing, Biomedical Engineering Program, University of South Carolina, Columbia, SC 29208
| | - Jay D. Potts
- School of Medicine, Department of Cell Biology and Anatomy, College of Engineering and Computing, Biomedical Engineering Program, University of South Carolina, Columbia, SC 29208
| | - John F. Eberth
- School of Medicine, Department of Cell Biology and Anatomy, College of Engineering and Computing, Biomedical Engineering Program, University of South Carolina, Columbia, SC 29208 e-mail:
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17
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Sadasivan C, Lieber BB, Woo HH. Physical Simulators and Replicators in Endovascular Neurosurgery Training. COMPREHENSIVE HEALTHCARE SIMULATION: NEUROSURGERY 2018. [DOI: 10.1007/978-3-319-75583-0_3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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18
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A New Multi-Mode Perfusion System for Ex Vivo Heart Perfusion Study. J Med Syst 2017; 42:25. [PMID: 29273867 DOI: 10.1007/s10916-017-0882-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Accepted: 12/13/2017] [Indexed: 10/18/2022]
Abstract
Ex vivo heart perfusion has been shown to be an effective means of facilitating the resuscitation and assessment of donor hearts for cardiac transplantation. Over the last ten years however, only a few ex vivo perfusion systems have been developed for this application. While results have been promising, a system capable of facilitating multiple perfusion strategies on the same platform has not yet been realized. In this paper, the design, development and testing of a novel and modular ex vivo perfusion system is described. The system is capable of operating in three unique primary modes: the traditional Langendorff Mode, Pump-Supported Working-Mode, and Passive Afterload Working-Mode. In each mode, physiological hemodynamic parameters can be produced by managing perfusion settings. To evaluate heart viability, six experiments were conducted using porcine hearts and measuring several parameters including: pH, aortic pressure, lactate metabolism, coronary vascular resistance (CVR), and myocardial oxygen consumption. Pressure-volume relationship measurements were used to assess left ventricular contractility in each Working Mode. Hemodynamic and metabolic conditions remained stable and consistent across 4 h of ex vivo heart perfusion on the ex vivo perfusion system, validating the system as a viable platform for future development of novel preservation and assessment strategies.
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19
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Kheyfets VO, Dunning J, Truong U, Ivy D, Hunter K, Shandas R. A Zero-Dimensional Model and Protocol for Simulating Patient-Specific Pulmonary Hemodynamics From Limited Clinical Data. J Biomech Eng 2017; 138:2565256. [PMID: 27684888 DOI: 10.1115/1.4034830] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Indexed: 11/08/2022]
Abstract
In pulmonary hypertension (PH) diagnosis and management, many useful functional markers have been proposed that are unfeasible for clinical implementation. For example, assessing right ventricular (RV) contractile response to a gradual increase in pulmonary arterial (PA) impedance requires simultaneously recording RV pressure and volume, and under different afterload/preload conditions. In addition to clinical applications, many research projects are hampered by limited retrospective clinical data and could greatly benefit from simulations that extrapolate unavailable hemodynamics. The objective of this study was to develop and validate a 0D computational model, along with a numerical implementation protocol, of the RV-PA axis. Model results are qualitatively compared with published clinical data and quantitatively validated against right heart catheterization (RHC) for 115 pediatric PH patients. The RV-PA circuit is represented using a general elastance function for the RV and a three-element Windkessel initial value problem for the PA. The circuit mathematically sits between two reservoirs of constant pressure, which represent the right and left atriums. We compared Pmax, Pmin, mPAP, cardiac output (CO), and stroke volume (SV) between the model and RHC. The model predicted between 96% and 98% of the variability in pressure and 98-99% in volumetric characteristics (CO and SV). However, Bland Altman plots showed the model to have a consistent bias for most pressure and volumetric parameters, and differences between model and RHC to have considerable error. Future studies will address this issue and compare specific waveforms, but these initial results are extremely promising as preliminary proof of concept of the modeling approach.
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Affiliation(s)
- Vitaly O Kheyfets
- University of Colorado Anschutz Medical Campus, Children's Hospital Colorado, Aurora, CO 80045 e-mail:
| | - Jamie Dunning
- University of Colorado Anschutz Medical Campus, Children's Hospital Colorado, Aurora, CO 80045 e-mail:
| | - Uyen Truong
- University of Colorado Anschutz Medical Campus, Children's Hospital Colorado, Aurora, CO 80045 e-mail:
| | - Dunbar Ivy
- University of Colorado Anschutz Medical Campus, Children's Hospital Colorado, Aurora, CO 80045 e-mail:
| | - Kendall Hunter
- University of Colorado Anschutz Medical Campus, Children's Hospital Colorado, Aurora, CO 80045 e-mail:
| | - Robin Shandas
- University of Colorado Anschutz Medical Campus, Children's Hospital Colorado, Aurora, CO 80045 e-mail:
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20
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Garrett AS, Pham T, Loiselle DS, Taberner AJ. Real-time model-based control of afterload for in vitro cardiac tissue experimentation. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2017; 2017:1287-1290. [PMID: 29060111 DOI: 10.1109/embc.2017.8037067] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The performance of mechanical work by isolated cardiac muscle samples has typically been studied by subjecting their tissues to an isotonic shortening protocol, which results in "flat-topped" work-loop profiles. In order to better replicate the forces experienced by these tissues in vivo, we have developed a system for imposing a model-based, time-varying, load on isolated cardiac tissue preparations. A model of systemic afterload was developed from the combination of a Windkessel-type model of vascular fluid impedance, and the Laplace law of the heart, and encoded into a hardware-based control system. The model-predicted length change was then imposed on an isolated cardiac trabecula in a work-loop calorimeter, giving rise to force-length work-loops that more closely resemble those experienced by these tissues in vivo.
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21
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Mechoor RR, Schmidt T, Kung E. A Real-Time Programmable Pulsatile Flow Pump for In Vitro Cardiovascular Experimentation. J Biomech Eng 2016; 138:2551746. [PMID: 27590025 DOI: 10.1115/1.4034561] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2016] [Indexed: 05/10/2024]
Abstract
Benchtop in vitro experiments are valuable tools for investigating the cardiovascular system and testing medical devices. Accurate reproduction of the physiologic flow waveforms at various anatomic locations is an important component of these experimental methods. This study discusses the design, construction, and testing of a low-cost and fully programmable pulsatile flow pump capable of continuously producing unlimited cycles of physiologic waveforms. It consists of a gear pump actuated by an AC servomotor and a feedback algorithm to achieve highly accurate reproduction of flow waveforms for flow rates up to 300 ml/s across a range of loading conditions. The iterative feedback algorithm uses the flow error values in one iteration to modify the motor control waveform for the next iteration to better match the desired flow. Within four to seven iterations of feedback, the pump replicated desired physiologic flow waveforms to within 2% normalized RMS error (for flow rates above 20 mL/s) under varying downstream impedances. This pump device is significantly more affordable (∼10% of the cost) than current commercial options. More importantly, the pump can be controlled via common scientific software and thus easily implemented into large automation frameworks.
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Affiliation(s)
- Rahul Raj Mechoor
- Department of Mechanical Engineering, Clemson University, 252 Fluor Daniel EIB, Clemson, SC 29631 e-mail:
| | - Tyler Schmidt
- Department of Mechanical Engineering, Clemson University, 252 Fluor Daniel EIB, Clemson, SC 29631 e-mail:
| | - Ethan Kung
- Mem. ASME Department of Mechanical Engineering, Clemson University, 231 Fluor Daniel EIB, Clemson, SC 29634-0921 e-mail:
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22
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A High Performance Pulsatile Pump for Aortic Flow Experiments in 3-Dimensional Models. Cardiovasc Eng Technol 2016; 7:148-58. [PMID: 26983961 DOI: 10.1007/s13239-016-0260-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 03/03/2016] [Indexed: 10/22/2022]
Abstract
Aortic pathologies such as coarctation, dissection, and aneurysm represent a particularly emergent class of cardiovascular diseases. Computational simulations of aortic flows are growing increasingly important as tools for gaining understanding of these pathologies, as well as for planning their surgical repair. In vitro experiments are required to validate the simulations against real world data, and the experiments require a pulsatile flow pump system that can provide physiologic flow conditions characteristic of the aorta. We designed a newly capable piston-based pulsatile flow pump system that can generate high volume flow rates (850 mL/s), replicate physiologic waveforms, and pump high viscosity fluids against large impedances. The system is also compatible with a broad range of fluid types, and is operable in magnetic resonance imaging environments. Performance of the system was validated using image processing-based analysis of piston motion as well as particle image velocimetry. The new system represents a more capable pumping solution for aortic flow experiments than other available designs, and can be manufactured at a relatively low cost.
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23
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Zhou J, Esmaily-Moghadam M, Conover TA, Hsia TY, Marsden AL, Figliola RS. In Vitro Assessment of the Assisted Bidirectional Glenn Procedure for Stage One Single Ventricle Repair. Cardiovasc Eng Technol 2015; 6:256-67. [PMID: 26577359 DOI: 10.1007/s13239-015-0232-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 06/25/2015] [Indexed: 11/28/2022]
Abstract
This in vitro study compares the hemodynamic performance of the Norwood and the Glenn circulations to assess the performance of a novel assisted bidirectional Glenn (ABG) procedure for stage one single ventricle surgery. In the ABG, the flow in a bidirectional Glenn procedure is assisted by injection of a high-energy flow stream from the systemic circulation using an aorta-caval shunt with nozzle. The aim is to explore experimentally the potential of the ABG as a surgical alternative to current surgical practice. The experiments are directly compared against previously published numerical simulations. A multiscale mock circulatory system was used to measure the hemodynamic performance of the three circulations. For each circulation, the system was tested using both low and high values of pulmonary vascular resistance. Resulting parameters measured were: pressure and flow rate at left/right pulmonary artery and superior vena cava (SVC). Systemic oxygen delivery (OD) was calculated. A parametric study of the ratio of ABG nozzle to shunt diameter was done. We report time-based comparisons with numerical simulations for the three surgical variants tested. The ABG circulation demonstrated an increase of 30-38% in pulmonary flow with a 2-3.7 mmHg increase in SVC pressure compared to the Glenn and a 4-14% higher systemic OD than either the Norwood or the Glenn. The nozzle/shunt diameter ratio affected the local hemodynamics. These experimental results agreed with those of the numerical model: mean flow values were not significantly different (p > 0.05) while mean pressures were comparable within 1.2 mmHg. The results verify the approaches providing two tools to study this complicated circulation. Using a realistic experimental model we demonstrate the performance of a novel surgical procedure with potential to improve patient hemodynamics in early palliation of the univentricular circulation.
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Affiliation(s)
- Jian Zhou
- Department of Mechanical Engineering, Clemson University, 247 Fluor Daniel Building, Clemson, SC, 29634, USA
| | | | - Timothy A Conover
- Department of Mechanical Engineering, Clemson University, 247 Fluor Daniel Building, Clemson, SC, 29634, USA
| | | | - Alison L Marsden
- Mechanical and Aerospace Engineering Department, University of California, San Diego, La Jolla, CA, USA
| | - Richard S Figliola
- Department of Mechanical Engineering, Clemson University, 247 Fluor Daniel Building, Clemson, SC, 29634, USA.
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Lillie JS, Liberson AS, Mix D, Schwarz KQ, Chandra A, Phillips DB, Day SW, Borkholder DA. Pulse Wave Velocity Prediction and Compliance Assessment in Elastic Arterial Segments. Cardiovasc Eng Technol 2014; 6:49-58. [PMID: 26577102 DOI: 10.1007/s13239-014-0202-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Accepted: 11/06/2014] [Indexed: 01/05/2023]
Abstract
Pressure wave velocity (PWV) is commonly used as a clinical marker of vascular elasticity. Recent studies have increased clinical interest in also analyzing the impact of heart rate, blood pressure, and left ventricular ejection time on PWV. In this article we focus on the development of a theoretical one-dimensional model and validation via direct measurement of the impact of ejection time and peak pressure on PWV using an in vitro hemodynamic simulator. A simple nonlinear traveling wave model was developed for a compliant thin-walled elastic tube filled with an incompressible fluid. This model accounts for the convective fluid phenomena, elastic vessel deformation, radial motion, and inertia of the wall. An exact analytical solution for PWV is presented which incorporates peak pressure, ejection time, ejection volume, and modulus of elasticity. To assess arterial compliance, the solution is introduced in an alternative form, explicitly determining compliance of the wall as a function of the other variables. The model predicts PWV in good agreement with the measured values with a maximum difference of 3.0%. The results indicate an inverse quadratic relationship ([Formula: see text]) between ejection time and PWV, with ejection time dominating the PWV shifts (12%) over those observed with changes in peak pressure (2%). Our modeling and validation results both explain and support the emerging evidence that, both in clinical practice and clinical research, cardiac systolic function related variables should be regularly taken into account when interpreting arterial function indices, namely PWV.
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Affiliation(s)
| | | | - Doran Mix
- University of Rochester, Rochester, NY, USA
| | | | | | | | - Steven W Day
- Rochester Institute of Technology, Rochester, NY, USA
| | - David A Borkholder
- Rochester Institute of Technology, Rochester, NY, USA.
- University of Rochester, Rochester, NY, USA.
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25
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Harmouche M, Maasrani M, Verhoye JP, Corbineau H, Drochon A. Coronary three-vessel disease with occlusion of the right coronary artery: What are the most important factors that determine the right territory perfusion? Ing Rech Biomed 2014. [DOI: 10.1016/j.irbm.2013.11.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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26
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Mock circulatory system of the Fontan circulation to study respiration effects on venous flow behavior. ASAIO J 2013; 59:253-60. [PMID: 23644612 DOI: 10.1097/mat.0b013e318288a2ab] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
We describe an in vitro model of the Fontan circulation with respiration to study subdiaphragmatic venous flow behavior. The venous and arterial connections of a total cavopulmonary connection (TCPC) test section were coupled with a physical lumped parameter (LP) model of the circulation. Intrathoracic and subdiaphragmatic pressure changes associated with normal breathing were applied. This system was tuned for two patients (5 years, 0.67 m2; 10 years, 1.2 m2) to physiological values. System function was verified by comparison to the analytical model on which it was based and by consistency with published clinical measurements. Overall, subdiaphragmatic venous flow was influenced by respiration. Flow within the arteries and veins increased during inspiration but decreased during expiration, with retrograde flow in the inferior venous territories. System pressures and flows showed close agreement with the analytical LP model (p < 0.05). The ratio of the flow rates occurring during inspiration to expiration were within the clinical range of values reported elsewhere. The approach used to set up and control the model was effective and provided reasonable comparisons with clinical data.
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27
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Kheyfets VO, O'Dell W, Smith T, Reilly JJ, Finol EA. Considerations for numerical modeling of the pulmonary circulation--a review with a focus on pulmonary hypertension. J Biomech Eng 2013; 135:61011-15. [PMID: 23699723 PMCID: PMC3705788 DOI: 10.1115/1.4024141] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Revised: 03/25/2013] [Accepted: 04/04/2013] [Indexed: 12/12/2022]
Abstract
Both in academic research and in clinical settings, virtual simulation of the cardiovascular system can be used to rapidly assess complex multivariable interactions between blood vessels, blood flow, and the heart. Moreover, metrics that can only be predicted with computational simulations (e.g., mechanical wall stress, oscillatory shear index, etc.) can be used to assess disease progression, for presurgical planning, and for interventional outcomes. Because the pulmonary vasculature is susceptible to a wide range of pathologies that directly impact and are affected by the hemodynamics (e.g., pulmonary hypertension), the ability to develop numerical models of pulmonary blood flow can be invaluable to the clinical scientist. Pulmonary hypertension is a devastating disease that can directly benefit from computational hemodynamics when used for diagnosis and basic research. In the present work, we provide a clinical overview of pulmonary hypertension with a focus on the hemodynamics, current treatments, and their limitations. Even with a rich history in computational modeling of the human circulation, hemodynamics in the pulmonary vasculature remains largely unexplored. Thus, we review the tasks involved in developing a computational model of pulmonary blood flow, namely vasculature reconstruction, meshing, and boundary conditions. We also address how inconsistencies between models can result in drastically different flow solutions and suggest avenues for future research opportunities. In its current state, the interpretation of this modeling technology can be subjective in a research environment and impractical for clinical practice. Therefore, considerations must be taken into account to make modeling reliable and reproducible in a laboratory setting and amenable to the vascular clinic. Finally, we discuss relevant existing models and how they have been used to gain insight into cardiopulmonary physiology and pathology.
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Affiliation(s)
- V. O. Kheyfets
- Department of Biomedical Engineering,The University of Texas at San Antonio,AET 1.360, One UTSA Circle,San Antonio, TX 78249
| | - W. O'Dell
- Department of Radiation Oncology,University of Florida,Shands Cancer Center,P.O. Box 100385,2033 Mowry Road,Gainesville, FL 32610
| | - T. Smith
- Western Allegheny Health System,Allegheny General Hospital,Gerald McGinnis Cardiovascular Institute,320 East North Avenue,Pittsburgh, PA 15212
| | - J. J. Reilly
- Department of Medicine,The University of Pittsburgh,1218 Scaife Hall,3550 Terrace Street,Pittsburgh, PA 15261
| | - E. A. Finol
- Department of Biomedical Engineering,The University of Texas at San Antonio,AET 1.360, One UTSA Circle,San Antonio, TX 78249e-mail:
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Kung EO, Les AS, Medina F, Wicker RB, McConnell MV, Taylor CA. In vitro validation of finite-element model of AAA hemodynamics incorporating realistic outlet boundary conditions. J Biomech Eng 2011; 133:041003. [PMID: 21428677 DOI: 10.1115/1.4003526] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The purpose of this study is to validate numerical simulations of flow and pressure in an abdominal aortic aneurysm (AAA) using phase-contrast magnetic resonance imaging (PCMRI) and an in vitro phantom under physiological flow and pressure conditions. We constructed a two-outlet physical flow phantom based on patient imaging data of an AAA and developed a physical Windkessel model to use as outlet boundary conditions. We then acquired PCMRI data in the phantom while it operated under conditions mimicking a resting and a light exercise physiological state. Next, we performed in silico numerical simulations and compared experimentally measured velocities, flows, and pressures in the in vitro phantom to those computed in the in silico simulations. There was a high degree of agreement in all of the pressure and flow waveform shapes and magnitudes between the experimental measurements and simulated results. The average pressures and flow split difference between experiment and simulation were all within 2%. Velocity patterns showed good agreement between experimental measurements and simulated results, especially in the case of whole-cycle averaged comparisons. We demonstrated methods to perform in vitro phantom experiments with physiological flows and pressures, showing good agreement between numerically simulated and experimentally measured velocity fields and pressure waveforms in a complex patient-specific AAA geometry.
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Affiliation(s)
- Ethan O Kung
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
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Kung EO, Les AS, Figueroa CA, Medina F, Arcaute K, Wicker RB, McConnell MV, Taylor CA. In vitro validation of finite element analysis of blood flow in deformable models. Ann Biomed Eng 2011; 39:1947-60. [PMID: 21404126 DOI: 10.1007/s10439-011-0284-7] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2010] [Accepted: 02/21/2011] [Indexed: 11/26/2022]
Abstract
The purpose of this article is to validate numerical simulations of flow and pressure incorporating deformable walls using in vitro flow phantoms under physiological flow and pressure conditions. We constructed two deformable flow phantoms mimicking a normal and a restricted thoracic aorta, and used a Windkessel model at the outlet boundary. We acquired flow and pressure data in the phantom while it operated under physiological conditions. Next, in silico numerical simulations were performed, and velocities, flows, and pressures in the in silico simulations were compared to those measured in the in vitro phantoms. The experimental measurements and simulated results of pressure and flow waveform shapes and magnitudes compared favorably at all of the different measurement locations in the two deformable phantoms. The average difference between measured and simulated flow and pressure was approximately 3.5 cc/s (13% of mean) and 1.5 mmHg (1.8% of mean), respectively. Velocity patterns also showed good qualitative agreement between experiment and simulation especially in regions with less complex flow patterns. We demonstrated the capabilities of numerical simulations incorporating deformable walls to capture both the vessel wall motion and wave propagation by accurately predicting the changes in the flow and pressure waveforms at various locations down the length of the deformable flow phantoms.
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Affiliation(s)
- Ethan O Kung
- Department of Bioengineering, James H. Clark Center, Stanford University, Stanford, CA 94305, USA
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