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Kozitza CJ, Colebank MJ, Gonzalez-Pereira JP, Chesler NC, Lamers L, Roldán-Alzate A, Witzenburg CM. Estimating pulmonary arterial remodeling via an animal-specific computational model of pulmonary artery stenosis. Biomech Model Mechanobiol 2024:10.1007/s10237-024-01850-6. [PMID: 38918266 DOI: 10.1007/s10237-024-01850-6] [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: 01/20/2024] [Accepted: 04/17/2024] [Indexed: 06/27/2024]
Abstract
Pulmonary artery stenosis (PAS) often presents in children with congenital heart disease, altering blood flow and pressure during critical periods of growth and development. Variability in stenosis onset, duration, and severity result in variable growth and remodeling of the pulmonary vasculature. Computational fluid dynamics (CFD) models enable investigation into the hemodynamic impact and altered mechanics associated with PAS. In this study, a one-dimensional (1D) fluid dynamics model was used to simulate hemodynamics throughout the pulmonary arteries of individual animals. The geometry of the large pulmonary arteries was prescribed by animal-specific imaging, whereas the distal vasculature was simulated by a three-element Windkessel model at each terminal vessel outlet. Remodeling of the pulmonary vasculature, which cannot be measured in vivo, was estimated via model-fitted parameters. The large artery stiffness was significantly higher on the left side of the vasculature in the left pulmonary artery (LPA) stenosis group, but neither side differed from the sham group. The sham group exhibited a balanced distribution of total distal vascular resistance, whereas the left side was generally larger in the LPA stenosis group, with no significant differences between groups. In contrast, the peripheral compliance on the right side of the LPA stenosis group was significantly greater than the corresponding side of the sham group. Further analysis indicated the underperfused distal vasculature likely moderately decreased in radius with little change in stiffness given the increase in thickness observed with histology. Ultimately, our model enables greater understanding of pulmonary arterial adaptation due to LPA stenosis and has potential for use as a tool to noninvasively estimate remodeling of the pulmonary vasculature.
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Affiliation(s)
- Callyn J Kozitza
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | - Mitchel J Colebank
- Edwards Lifesciences Foundation Cardiovascular Innovation and Research Center, and Department of Biomedical Engineering, University of California, Irvine, Irvine, CA, USA
| | | | - Naomi C Chesler
- Edwards Lifesciences Foundation Cardiovascular Innovation and Research Center, and Department of Biomedical Engineering, University of California, Irvine, Irvine, CA, USA
| | - Luke Lamers
- Pediatrics, Division of Cardiology, University of Wisconsin-Madison, Madison, WI, USA
| | - Alejandro Roldán-Alzate
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, USA
- Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI, USA
- Department of Radiology, University of Wisconsin-Madison, Madison, WI, USA
| | - Colleen M Witzenburg
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, USA.
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Hayashi H, Contento J, Matsushita H, Mass P, Cleveland V, Aslan S, Dave A, Santos RD, Zhu A, Reid E, Watanabe T, Lee N, Dunn T, Siddiqi U, Nurminsky K, Nguyen V, Kawaji K, Huddle J, Pocivavsek L, Johnson J, Fuge M, Loke YH, Krieger A, Olivieri L, Hibino N. Patient-specific tissue engineered vascular graft for aortic arch reconstruction. JTCVS OPEN 2024; 18:209-220. [PMID: 38690440 PMCID: PMC11056495 DOI: 10.1016/j.xjon.2024.02.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 01/21/2024] [Accepted: 02/05/2024] [Indexed: 05/02/2024]
Abstract
Objectives The complexity of aortic arch reconstruction due to diverse 3-dimensional geometrical abnormalities is a major challenge. This study introduces 3-dimensional printed tissue-engineered vascular grafts, which can fit patient-specific dimensions, optimize hemodynamics, exhibit antithrombotic and anti-infective properties, and accommodate growth. Methods We procured cardiac magnetic resonance imaging with 4-dimensional flow for native porcine anatomy (n = 10), from which we designed tissue-engineered vascular grafts for the distal aortic arch, 4 weeks before surgery. An optimal shape of the curved vascular graft was designed using computer-aided design informed by computational fluid dynamics analysis. Grafts were manufactured and implanted into the distal aortic arch of porcine models, and postoperative cardiac magnetic resonance imaging data were collected. Pre- and postimplant hemodynamic data and histology were analyzed. Results Postoperative magnetic resonance imaging of all pigs with 1:1 ratio of polycaprolactone and poly-L-lactide-co-ε-caprolactone demonstrated no specific dilatation or stenosis of the graft, revealing a positive growth trend in the graft area from the day after surgery to 3 months later, with maintaining a similar shape. The peak wall shear stress of the polycaprolactone/poly-L-lactide-co-ε-caprolactone graft portion did not change significantly between the day after surgery and 3 months later. Immunohistochemistry showed endothelization and smooth muscle layer formation without calcification of the polycaprolactone/poly-L-lactide-co-ε-caprolactone graft. Conclusions Our patient-specific polycaprolactone/poly-L-lactide-co-ε-caprolactone tissue-engineered vascular grafts demonstrated optimal anatomical fit maintaining ideal hemodynamics and neotissue formation in a porcine model. This study provides a proof of concept of patient-specific tissue-engineered vascular grafts for aortic arch reconstruction.
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Affiliation(s)
- Hidenori Hayashi
- Division of Cardiac Surgery, Department of Surgery, University of Chicago, Chicago, Ill
| | | | - Hiroshi Matsushita
- Division of Cardiac Surgery, Department of Surgery, University of Chicago, Chicago, Ill
| | - Paige Mass
- Department of Cardiology, Children's National Hospital, Washington, DC
| | - Vincent Cleveland
- Department of Cardiology, Children's National Hospital, Washington, DC
| | - Seda Aslan
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Md
| | - Amartya Dave
- Division of Cardiac Surgery, Department of Surgery, University of Chicago, Chicago, Ill
| | - Raquel dos Santos
- Division of Cardiac Surgery, Department of Surgery, University of Chicago, Chicago, Ill
| | - Angie Zhu
- Division of Cardiac Surgery, Department of Surgery, University of Chicago, Chicago, Ill
| | - Emmett Reid
- Division of Cardiac Surgery, Department of Surgery, University of Chicago, Chicago, Ill
| | - Tatsuya Watanabe
- Division of Cardiac Surgery, Department of Surgery, University of Chicago, Chicago, Ill
| | - Nora Lee
- Division of Cardiac Surgery, Department of Surgery, University of Chicago, Chicago, Ill
| | - Tyler Dunn
- Division of Cardiac Surgery, Department of Surgery, University of Chicago, Chicago, Ill
| | - Umar Siddiqi
- Division of Cardiac Surgery, Department of Surgery, University of Chicago, Chicago, Ill
| | - Katherine Nurminsky
- Division of Cardiac Surgery, Department of Surgery, University of Chicago, Chicago, Ill
| | - Vivian Nguyen
- Department of Biomedical Engineering, Illinois Institute of Technology, Chicago, Ill
| | - Keigo Kawaji
- Department of Biomedical Engineering, Illinois Institute of Technology, Chicago, Ill
| | | | - Luka Pocivavsek
- Division of Vascular Surgery, Department of Surgery, University of Chicago, Chicago, Ill
| | | | - Mark Fuge
- Department of Mechanical Engineering, University of Maryland, College Park, Md
| | - Yue-Hin Loke
- Department of Cardiology, Children's National Hospital, Washington, DC
| | - Axel Krieger
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Md
| | - Laura Olivieri
- Department of Pediatric Cardiology, University of Pittsburgh Medical Center, Pittsburgh, Pa
| | - Narutoshi Hibino
- Division of Cardiac Surgery, Department of Surgery, University of Chicago, Chicago, Ill
- Department of Cardiovascular Surgery, Advocate Children's Hospital, Oak Lawn, Ill
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Yu P, Xiong J, Tong Z, Chen L, Hu L, Liu J, Liu J. Hemodynamic-based virtual surgery design of double-patch repair for pulmonary arterioplasty in tetralogy of Fallot. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2024; 245:108012. [PMID: 38246096 DOI: 10.1016/j.cmpb.2024.108012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 12/26/2023] [Accepted: 01/08/2024] [Indexed: 01/23/2024]
Abstract
BACKGROUND AND OBJECTIVE Surgical correction of pulmonary artery stenosis (PAS) is essential to the prognosis of patients with tetralogy of Fallot (TOF). The double-patch method of pulmonary arterioplasty is usually applied in case of multiple stenosis in TOF patients' pulmonary artery (PA) and when PAS cannot be relieved by the single-patch method. The surgical planning for the double-patch design remains challenging. The purpose of this study is to investigate the double-patch design with different angulations between the left pulmonary artery (LPA) and the right pulmonary artery (RPA), and to understand postoperative hemodynamic alterations by the application of computer-aided design (CAD) and computational fluid dynamics (CFD) techniques. METHODS The three-dimensional model of the PA was reconstructed based on preoperative computed tomography imaging data obtained from the patient with TOF. Three postoperative models with different designs of double-patch were created by "virtual surgery" using the CAD technique. Double-Patch 120 Model was created with double patches implanted in the main pulmonary artery (MPA) and the PA bifurcation and without changing the spatial position of PA. The angulation between the LPA and the RPA was defined as θ, which equaled to 120° in Pre-Operative Model and Double-Patch 120 Model. Based on Double-Patch 120 Model, Double-Patch 110 Model and Double-Patch 130 Model were generated with θ equaled to 110° and 130°, respectively. Combined with CFD, the differences of velocity streamlines, wall shear stress (WSS), flow distribution ratio (FDR), and energy loss (EL) were compared to analyze postoperative pulmonary flow characteristics. RESULTS The values of velocity and WSS decreased significantly after virtual surgery. Obvious vortices and swirling flows were observed downstream of the stenosis of RPA and LPA in Pre-Operative Model, while fewer vortices developed along the anterior wall of the expanded lumens of RPA, especially in Double-Patch 110 Model. With the relief of PAS, two relatively higher WSS regions were observed at the posterior walls of RPA and LPA. The maximum WSS values in these regions of Double-Patch 110 Model were lower than those in Double-Patch 120 Model and Double-Patch 130 Model. Furthermore, the FDRs were elevated and the ELs were greatly reduced. It was found that Double-Patch 110 Model with the angulation between the LPA and the RPA equaled to 110° showed relatively better properties of hemodynamics than other models. CONCLUSIONS The angulation between the LPA and the RPA is an important factor that should be integrated in the double-patch design for TOF repair. Virtual surgery based on patient-specific vascular model and computational hemodynamics can be used to provide assistance for individualized surgical planning of double-patch arterioplasty.
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Affiliation(s)
- Pingping Yu
- Institute of Pediatric Translational Medicine, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China; Department of Cardiothoracic Surgery, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China; Shanghai Institute for Pediatric Congenital Heart Disease, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
| | - Jiwen Xiong
- Institute of Pediatric Translational Medicine, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China; Department of Cardiothoracic Surgery, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China; Shanghai Institute for Pediatric Congenital Heart Disease, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China; Shanghai Engineering Research Center of Virtual Reality of Structural Heart Disease, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
| | - Zhirong Tong
- Institute of Pediatric Translational Medicine, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China; Shanghai Institute for Pediatric Congenital Heart Disease, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China; Shanghai Engineering Research Center of Virtual Reality of Structural Heart Disease, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
| | - Lijun Chen
- Department of Pediatric Cardiology, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
| | - Liwei Hu
- Department of Radiology, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
| | - Jinfen Liu
- Department of Cardiothoracic Surgery, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China; Shanghai Institute for Pediatric Congenital Heart Disease, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China; Shanghai Engineering Research Center of Virtual Reality of Structural Heart Disease, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
| | - Jinlong Liu
- Institute of Pediatric Translational Medicine, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China; Department of Cardiothoracic Surgery, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China; Shanghai Institute for Pediatric Congenital Heart Disease, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China; Shanghai Engineering Research Center of Virtual Reality of Structural Heart Disease, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China.
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Aljassam Y, Caputo M, Biglino G. Surgical Patching in Congenital Heart Disease: The Role of Imaging and Modelling. Life (Basel) 2023; 13:2295. [PMID: 38137896 PMCID: PMC10745019 DOI: 10.3390/life13122295] [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: 10/04/2023] [Revised: 11/28/2023] [Accepted: 11/29/2023] [Indexed: 12/24/2023] Open
Abstract
In congenital heart disease, patches are not tailored to patient-specific anatomies, leading to shape mismatch with likely functional implications. The design of patches through imaging and modelling may be beneficial, as it could improve clinical outcomes and reduce the costs associated with redo procedures. Whilst attention has been paid to the material of the patches used in congenital surgery, this review outlines the current knowledge on this subject and isolated experimental work that uses modelling and imaging-derived information (including 3D printing) to inform the design of the surgical patch.
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Affiliation(s)
- Yousef Aljassam
- Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol BS2 8HW, UK;
| | - Massimo Caputo
- Bristol Heart Institute, Bristol Medical School, University of Bristol, Bristol BS2 8HW, UK;
- Cardiac Surgery, University Hospitals Bristol & Weston, NHS Foundation Trust, Bristol BS2 8HW, UK
| | - Giovanni Biglino
- Bristol Heart Institute, Bristol Medical School, University of Bristol, Bristol BS2 8HW, UK;
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Kamada H, Nakamura M, Ota H, Higuchi S, Takase K. Blood flow analysis with computational fluid dynamics and 4D-flow MRI for vascular diseases. J Cardiol 2022; 80:386-396. [PMID: 35718672 DOI: 10.1016/j.jjcc.2022.05.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 05/16/2022] [Indexed: 10/31/2022]
Abstract
Both computational fluid dynamics (CFD) and time-resolved, three-dimensional, phase-contrast, magnetic resonance imaging (4D-flow MRI) enable visualization of time-varying blood flow structures and quantification of blood flow in vascular diseases. However, they are totally different. CFD is a method to calculate blood flow by solving the governing equations of fluid mechanics, so the obtained flow field is somewhat virtual. On the other hand, 4D-flow MRI measures blood flow in vivo, thus the flow is real. Recently, with the development and enhancement of computers, medical imaging techniques, and related software, blood flow analysis has become more accessible to clinicians and its usefulness in vascular diseases has been demonstrated. In this review, we have outlined the methods and characteristics of CFD and 4D-flow MRI, respectively. We have discussed the differences in the characteristics between both methods; reviewed the milestones achieved by blood flow analysis in various vascular diseases; and discussed the usefulness, challenges, and limitations of blood flow analysis. We have discussed the difficulties and limitations of current blood flow analysis. We have also discussed our views on future directions.
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Affiliation(s)
- Hiroki Kamada
- Department of Diagnostic Radiology, Tohoku University Hospital, Sendai, Japan.
| | - Masanori Nakamura
- Department of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Nagoya, Japan
| | - Hideki Ota
- Department of Diagnostic Radiology, Tohoku University Hospital, Sendai, Japan
| | - Satoshi Higuchi
- Department of Diagnostic Radiology, Tohoku University Hospital, Sendai, Japan
| | - Kei Takase
- Department of Diagnostic Radiology, Tohoku University Hospital, Sendai, Japan
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Conijn M, Krings GJ. Understanding stenotic pulmonary arteries: Can computational fluid dynamics help us out? PROGRESS IN PEDIATRIC CARDIOLOGY 2022. [DOI: 10.1016/j.ppedcard.2021.101452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Computational Analysis of the Pulmonary Arteries in Congenital Heart Disease: A Review of the Methods and Results. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2021; 2021:2618625. [PMID: 33868449 PMCID: PMC8035004 DOI: 10.1155/2021/2618625] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 02/25/2021] [Accepted: 03/12/2021] [Indexed: 11/17/2022]
Abstract
With the help of computational fluid dynamics (CFD), hemodynamics of the pulmonary arteries (PA's) can be studied in detail and varying physiological circumstances and treatment options can be simulated. This offers the opportunity to improve the diagnostics and treatment of PA stenosis in biventricular congenital heart disease (CHD). The aim of this review was to evaluate the methods of computational studies for PA's in biventricular CHD and the level of validation of the numerical outcomes. A total of 34 original research papers were selected. The literature showed a great variety in the used methods for (re) construction of the geometry as well as definition of the boundary conditions and numerical setup. There were 10 different methods identified to define inlet boundary conditions and 17 for outlet boundary conditions. A total of nine papers verified their CFD outcomes by comparing results to clinical data or by an experimental mock loop. The diversity in used methods and the low level of validation of the outcomes result in uncertainties regarding the reliability of numerical studies. This limits the current clinical utility of CFD for the study of PA flow in CHD. Standardization and validation of the methods are therefore recommended.
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Nakamura Y, Romans C, Ashwath R. Patient-Specific Patch for an Intra-Atrial Rerouting Procedure Developed Through Surgical Simulation. World J Pediatr Congenit Heart Surg 2021; 12:234-243. [PMID: 33683998 DOI: 10.1177/2150135120985469] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND In pediatric cardiac surgery, an application of three-dimensional (3D) modeling to develop custom-made prostheses is limited, and currently surgeons use their intraoperative visual estimation to develop 3D complex structures from 2D patch materials. Contemporary 3D designers are developing complex surfaces using surface modeling in other industries, which can be applied to pediatric cardiac surgery. However, its free-form nature may lead to intradesigner variability. METHODS A patient with a body weight of 4 kg with partial anomalous pulmonary venous connection and preoperative computed tomography data was selected, and a patient-specific 3D heart model was obtained. Through collaboration with a pediatric cardiologist and a pediatric cardiac surgeon, a 3D designer developed two patient-specific 3D patches for an intra-atrial rerouting procedure (IAR) for the patient using different methods of surface modeling. The shape and size of two flattened patches were analyzed using a geometric morphometrics (GM) approach. Computational fluid dynamics (CFD) analysis was also performed to calculate pressure drop across streamlines and flow energy loss in the right atrium for both patches. RESULTS The GM analysis showed that the size and shape of the two patches around the systemic vein orifice, crucial to prevent systemic venous obstruction, were almost equivalent. However, the CFD analysis showed that the pressure drop and flow energy loss were almost twice for one patch compared with the other. CONCLUSIONS Our platform of developing a patient-specific 3D patch for an IAR procedure using surface modeling seemed promising, although intradesigner patch variability was not neglectable in our small-sized patient.
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Affiliation(s)
- Yuki Nakamura
- Division of Pediatric Cardiothoracic Surgery, 21782The University of Iowa, Iowa, IA, USA
| | | | - Ravi Ashwath
- Division of Pediatric Cardiology, 160412The University of Iowa, Iowa, IA, USA
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Computational fluid dynamics simulations of flow distribution and graft designs in apicoaortic bypass. Gen Thorac Cardiovasc Surg 2020; 69:811-818. [PMID: 33125595 DOI: 10.1007/s11748-020-01527-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 10/16/2020] [Indexed: 10/23/2022]
Abstract
OBJECTIVE Apicoaortic bypass has double outlets and its graft design is similar to that of a left ventricular assist device (LVAD). The left ventricular apex to the descending aorta (LV-DsAo) bypass is widely used in apicoaortic bypass. In contrast, the left ventricular apex to the ascending aorta (LV-AsAo) bypass is standard in LVAD surgery. This study aimed to evaluate the graft designs of apicoaortic bypass and their effects on flow distribution and energy loss (EL). METHODS A simulation study using computational fluid dynamics was performed on the geometry and hemodynamics data obtained from a 30-year-old patient who underwent a LV-DsAo bypass. The ratio of the cardiac output (CO) through the ascending aorta (AsAo) and apicoaortic conduit was set at 50:50, 30:70, and 10:90. Regional blood flow (RBF) and EL were calculated for the different distribution ratios. As an alternative to the LV-DsAo bypass, a virtual LV-AsAo bypass surgery was performed, and each parameter was compared with that of the LV-DsAo bypass. RESULTS At a distribution ratio of 50:50, the RBF to the head and EL were 16.4% of the total CO and 62.0 mW in the LV-DsAo bypass, and 32.3% and 81.5 mW in the LV-AsAo bypass, respectively. The RBF to the head decreased with the CO through the AsAo in the LV-DsAo bypass, but it was constant in the LV-AsAo bypass. The EL increased inversely with the CO through the AsAo in both graft designs. CONCLUSION The regional blood flow distribution was different, but the trend of the EL which increased inversely with the CO through the AsAo was similar between the LV-DsAo and LV-AsAo bypasses.
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