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Zijderhand CF, Peek JJ, Sjatskig J, Manintveld OC, Bekkers JA, Bogers AJJC, Caliskan K. Influence of the Outflow Graft Angular Position on the Outcomes in Patients With a Left Ventricular Assist Device. ASAIO J 2024; 70:861-867. [PMID: 38595102 DOI: 10.1097/mat.0000000000002189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/11/2024] Open
Abstract
This study aimed to explore the potential impact of the angular position of the outflow graft on thromboembolic events and aortic valve regurgitation in people with a left ventricular assist device (LVAD). We analyzed contrast computed tomography (CT) data of patients with LVAD implantation between 2016 and 2021. Three-dimensional reconstructions of the outflow graft and aortic arch were performed to calculate the horizontal (azimuth) angle and vertical (polar) angle, as well as the relative distance between the outflow graft, aortic valve, and brachiocephalic artery. Among 59 patients (median age 57, 68% male), a vertical angle ≥107° correlated significantly with increased cerebrovascular accidents (hazard ratio [HR]: 5.8, 95% confidence interval [CI]: 1.3-26.3, p = 0.022) and gastrointestinal bleeding (HR: 3.4, 95% CI: 1.0-11.2, p = 0.049) during a median 25 month follow-up. No significant differences were found between the vertical angle and aortic valve regurgitation or survival. The horizontal angle and relative distance did not show differences regarding clinical adverse events. This study emphasizes the importance of the LVAD outflow graft angular position to prevent life-threatening thromboembolic events. This study suggests the need for prospective research to further validate these findings.
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Affiliation(s)
- Casper F Zijderhand
- From the Thoraxcenter, Department of Cardiothoracic Surgery, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands
| | - Jette J Peek
- From the Thoraxcenter, Department of Cardiothoracic Surgery, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands
| | - Jelena Sjatskig
- From the Thoraxcenter, Department of Cardiothoracic Surgery, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands
| | - Olivier C Manintveld
- Thoraxcenter, Department of Cardiology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands
| | - Jos A Bekkers
- From the Thoraxcenter, Department of Cardiothoracic Surgery, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands
| | - Ad J J C Bogers
- From the Thoraxcenter, Department of Cardiothoracic Surgery, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands
| | - Kadir Caliskan
- Thoraxcenter, Department of Cardiology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands
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2
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Mansouri H, Kemerli M, MacIver R, Amili O. Development of idealized human aortic models for in vitro and in silico hemodynamic studies. Front Cardiovasc Med 2024; 11:1358601. [PMID: 39161662 PMCID: PMC11330894 DOI: 10.3389/fcvm.2024.1358601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Accepted: 06/25/2024] [Indexed: 08/21/2024] Open
Abstract
Background The aorta, a central component of the cardiovascular system, plays a pivotal role in ensuring blood circulation. Despite its importance, there is a notable lack of idealized models for experimental and computational studies. Objective This study aims to develop computer-aided design (CAD) models for the idealized human aorta, intended for studying hemodynamics or solid mechanics in both in vitro and in silico settings. Methods Various parameters were extracted from comprehensive literature sources to evaluate major anatomical characteristics of the aorta in healthy adults, including variations in aortic arch branches and corresponding dimensions. The idealized models were generated based on averages weighted by the cohort size of each study for several morphological parameters collected and compiled from image-based or cadaveric studies, as well as data from four recruited subjects. The models were used for hemodynamics assessment using particle image velocimetry (PIV) measurements and computational fluid dynamics (CFD) simulations. Results Two CAD models for the idealized human aorta were developed, focusing on the healthy population. The CFD simulations, which align closely with the PIV measurements, capture the main global flow features and wall shear stress patterns observed in patient-specific cases, demonstrating the capabilities of the designed models. Conclusions The collected statistical data on the aorta and the two idealized aorta models, covering prevalent arch variants known as Normal and Bovine types, are shown to be useful for examining the hemodynamics of the aorta. They also hold promise for applications in designing medical devices where anatomical statistics are needed.
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Affiliation(s)
- Hamid Mansouri
- Department of Mechanical, Industrial, and Manufacturing Engineering, University of Toledo, Toledo, OH, United States
| | - Muaz Kemerli
- Department of Mechanical, Industrial, and Manufacturing Engineering, University of Toledo, Toledo, OH, United States
- Department of Mechanical Engineering, Sakarya University, Sakarya, Turkey
| | - Robroy MacIver
- Children’s Heart Clinic, Children’s Hospitals and Clinics of Minnesota, Minneapolis, MN, United States
| | - Omid Amili
- Department of Mechanical, Industrial, and Manufacturing Engineering, University of Toledo, Toledo, OH, United States
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3
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Zambrano BA, Wilson SI, Zook S, Vekaria B, Moreno MR, Kassi M. Computational investigation of outflow graft variation impact on hemocompatibility profile in LVADs. Artif Organs 2024; 48:375-385. [PMID: 37962282 DOI: 10.1111/aor.14679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 10/17/2023] [Accepted: 10/29/2023] [Indexed: 11/15/2023]
Abstract
BACKGROUND Hemocompatibility-related adverse events (HRAE) occur commonly in patients with left ventricular assist devices (LVADs) and add to morbidity and mortality. It is unclear whether the outflow graft orientation can impact flow conditions leading to HRAE. This study presents a simulation-based approach using exact patient anatomy from medical images to investigate the influence of outflow cannula orientation in modulating flow conditions leading to HRAEs. METHODS A 3D model of a proximal aorta and outflow graft was reconstructed from a computed tomography (CT) scan of an LVAD patient and virtually modified to model multiple cannula orientations (n = 10) by varying polar (cranio-caudal) (n = 5) and off-set (anterior-posterior) (n = 2) angles. Time-dependent computational flow simulations were then performed for each anatomical orientation. Qualitative and quantitative hemodynamics metrics of thrombogenicity including time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), endothelial cell platelet activation potential (ECAP), particle residence time (PRT), and platelet activation potential (PLAP) were analyzed. RESULTS Within the simulations performed, endothelial cell activation potential (ECAP) and particle residence time (PRT) were found to be lowest with a polar angle of 85°, regardless of offset angle. However, polar angles that produced parameters at levels least associated with thrombosis varied when the offset angle was changed from 0° to 12°. For offset angles of 0° and 12° respectively, flow shear was lowest at 65° and 75°, time averaged wall shear stress (TAWSS) was highest at 85° and 35°, and platelet activation potential (PLAP) was lowest at 65° and 45°. CONCLUSION This study suggests that computational fluid dynamic modeling based on patient-specific anatomy can be a powerful analytical tool when identifying optimal positioning of an LVAD. Contrary to previous work, our findings suggest that there may be an "ideal" outflow cannula for each individual patient based on a CFD-based hemocompatibility profile.
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Affiliation(s)
- Byron A Zambrano
- J. Mike Walker '66 Department of Mechanical Engineering, Texas A&M University, College Station, Texas, USA
| | - Shannon I Wilson
- Department of Biomedical Engineering, Texas A&M University, College Station, Texas, USA
| | - Salma Zook
- Houston Methodist, Department of Cardiology, Houston Methodist Research Hospital, Houston, Texas, USA
| | - Bansi Vekaria
- Houston Methodist, Department of Cardiology, Houston Methodist Research Hospital, Houston, Texas, USA
| | - Michael R Moreno
- J. Mike Walker '66 Department of Mechanical Engineering, Texas A&M University, College Station, Texas, USA
| | - Mahwash Kassi
- Houston Methodist, Department of Cardiology, Houston Methodist Research Hospital, Houston, Texas, USA
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4
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Dankano A, Prather R, Lozinski B, Divo E, Kassab A, DeCampli W. Tailoring left ventricular assist device cannula implantation using coupled multi-scale multi-objective optimization. Med Eng Phys 2024; 125:104124. [PMID: 38508801 DOI: 10.1016/j.medengphy.2024.104124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Revised: 01/17/2024] [Accepted: 02/15/2024] [Indexed: 03/22/2024]
Abstract
BACKGROUND The frequent occurrence of thromboembolic cerebral events continues to limit the widespread implementation of Ventricular Assist Devices (VAD) despite continued advancements in VAD design and anti-coagulation treatments. Recent studies point to the optimal positioning of the outflow graft (OG) as a potential mitigator of post implantation thromboembolism. OBJECTIVE This study aims to examine the tailoring of the OG implantation orientation with the goal of minimizing the number of thrombi reaching the cerebral vessels by means of a formal shape optimization scheme incorporated into a multi-scale hemodynamics analysis. METHODS A 3-D patient-specific computational fluid dynamics model is loosely coupled in a two-way manner to a 0-D lumped parameter model of the peripheral circulation. A Lagrangian particle-tracking scheme models and tracks thrombi as non-interacting solid spheres. The loose coupling between CFD and LPM is integrated into a geometric shape optimization scheme which aims to optimize an objective function that targets a drop in cerebral embolization, and an overall reduction in particle residence times. RESULTS The results elucidate the importance of OG anastomosis orientation and placement particularly in the case that studied particle release from the OG, as a fivefold decrease in cerebral embolization was observed between the optimal and non-optimal implantations. Another case considered particle release from the ventricle and aortic root walls, in which optimal implantation was achieved with a shallow insertion angle. Particle release from all three origins was investigated in the third case, demonstrating that the optimal configurations were generally characterized by VAD flow directed along the central lumen of the aortic arch. Because optimal configurations depended on the anatomic origin of the thrombus, it is important to determine, in clinical studies, the most likely sites of thrombus formation in VAD patients.
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Affiliation(s)
- Abubakar Dankano
- Department of Mechanical and Aerospace Engineering, University of Central Florida, 4000 Central Florida Blvd, Orlando, FL 32816, United States.
| | - Ray Prather
- Arnold Palmer Children's Hospital, 92 West Miller St, Orlando, FL 32806, United States
| | - Blake Lozinski
- Department of Mechanical and Aerospace Engineering, University of Central Florida, 4000 Central Florida Blvd, Orlando, FL 32816, United States
| | - Eduardo Divo
- Department of Mechanical Engineering, Embry-Riddle Aeronautical University, 600 South Clyde Morris Blvd, Daytona Beach, FL 32114, United States
| | - Alain Kassab
- Department of Mechanical and Aerospace Engineering, University of Central Florida, 4000 Central Florida Blvd, Orlando, FL 32816, United States
| | - William DeCampli
- College of Medicine, University of Central Florida, Arnold Palmer Children's Hospital, 92 West Miller St, Orlando, FL 32806, United States
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Sahni A, McIntyre EE, Pal JD, Mukherjee D. Quantitative Assessment of Aortic Hemodynamics for Varying Left Ventricular Assist Device Outflow Graft Angles and Flow Pulsation. Ann Biomed Eng 2023; 51:1226-1243. [PMID: 36705866 DOI: 10.1007/s10439-022-03127-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 12/25/2022] [Indexed: 01/28/2023]
Abstract
Left ventricular assist devices (LVADs) comprise a primary treatment choice for advanced heart failure patients. Treatment with LVAD is commonly associated with complications like stroke and gastro-intestinal (GI) bleeding, which adversely impacts treatment outcomes, and causes fatalities. The etiology and mechanisms of these complications can be linked to the fact that LVAD outflow jet leads to an altered state of hemodynamics in the aorta as compared to baseline flow driven by aortic jet during ventricular systole. Here, we present a framework for quantitative assessment of aortic hemodynamics in LVAD flows realistic human vasculature, with a focus on quantifying the differences between flow driven by LVAD jet and the physiological aortic jet when no LVAD is present. We model hemodynamics in the aortic arch proximal to the LVAD outflow graft, as well as in the abdominal aorta away from the LVAD region. We characterize hemodynamics using quantitative descriptors of flow velocity, stasis, helicity, vorticity and mixing, and wall shear stress. These are used on a set of 27 LVAD scenarios obtained by parametrically varying LVAD outflow graft anastomosis angles, and LVAD flow pulse modulation. Computed descriptors for each of these scenarios are compared against the baseline flow, and a detailed quantitative characterization of the altered state of hemodynamics due to LVAD operation (when compared to baseline aortic flow) is compiled. These are interpreted using a conceptual model for LVAD flow that distinguishes between flow originating from the LVAD outflow jet (and its impingement on the aorta wall), and flow originating from aortic jet during aortic valve opening in normal physiological state.
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Affiliation(s)
- Akshita Sahni
- Department of Mechanical Engineering, University of Colorado Boulder, Boulder, USA
| | - Erin E McIntyre
- Division of Cardiothoracic Surgery, University of Colorado, Anschutz Medical Campus, Aurora, USA
| | - Jay D Pal
- Department of Surgery, University of Washington, Seattle, USA
| | - Debanjan Mukherjee
- Department of Mechanical Engineering, University of Colorado Boulder, Boulder, USA.
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Girfoglio M, Ballarin F, Infantino G, Nicoló F, Montalto A, Rozza G, Scrofani R, Comisso M, Musumeci F. Non-intrusive PODI-ROM for patient-specific aortic blood flow in presence of a LVAD device. Med Eng Phys 2022; 107:103849. [DOI: 10.1016/j.medengphy.2022.103849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Revised: 06/23/2022] [Accepted: 07/10/2022] [Indexed: 10/17/2022]
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7
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Chivukula VK, Loera G, Dragoljic D, Martinez J, Beckman JA, Li S, Mahr C, Aliseda A. A Computational Hemodynamics Approach to Left Ventricular Assist Device (LVAD) Optimization Validated in a Large Patient Cohort. ASAIO J 2022; 68:932-939. [PMID: 34743140 DOI: 10.1097/mat.0000000000001606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
With increasing use of left ventricular assist devices (LVAD) it is critical to devise strategies to optimize LVAD speed while controlling mean arterial pressure (MAP) and flow according to patient physiology. The complex interdependency between LVAD speed, MAP, and flow frequently makes optimization difficult under clinical conditions. We propose a method to guide this procedure in silico, narrowing the conditions to test clinically. A computational model of the circulatory network that simulates HF and LVAD support, incorporating LVAD pressure-flow curves was applied retrospectively to anonymized patient hemodynamics data from the University of Washington Medical Center. MAP management on 61 patient-specific computational models with a target of 70 mm Hg, resulting flow for a given LVAD speed was analyzed, and compared to a target output of 5 L/min. Before performing virtual MAP management, 51% had a MAP>70 mm Hg and CO>5 L/min, and 33% had a MAP>70 mm Hg and CO<5 L/min. After changing systemic resistance to meet the MAP target (without adjusting LVAD speed), 84% of cases resulted in CO higher than 5 L/min, with a median CO of 6.79 L/min, using the computational predictive model. Blood pressure management alone is insufficient in meeting both MAP and CO targets, due to the risk of hypervolemia, and requires appropriate LVAD speed optimization to achieve both targets, while preserving right heart health. Such computational tools can narrow down conditions to be tested for each patient, providing significant insight into the pump-patient interplay. LVAD hemodynamic optimization has the potential to reduce complications and improve outcomes.
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Affiliation(s)
| | - Gavin Loera
- Department of Biomedical Engineering, University of North Texas, Denton, Texas
| | - Dina Dragoljic
- Department of Biomedical Engineering, Florida Institute of Technology, Melbourne, Florida
| | - Jasmine Martinez
- Department of Biomedical Engineering, Florida Institute of Technology, Melbourne, Florida
| | | | - Song Li
- Division of Cardiology, University of Washington, Seattle, Washington
| | - Claudius Mahr
- Division of Cardiology, University of Washington, Seattle, Washington
| | - Alberto Aliseda
- Department of Mechanical Engineering, University of Washington, Seattle, Washington, USA
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8
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Prather R, Divo E, Kassab A, DeCampli W. In-silico analysis of outflow graft implantation orientation and cerebral thromboembolism incidence for full LVAD support. Comput Methods Biomech Biomed Engin 2021; 25:1249-1261. [PMID: 34812689 DOI: 10.1080/10255842.2021.2005789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
We investigate tailoring cannula implantation angles of left ventricle assist devices (LVAD) to reduce cerebral embolism risk for full LVAD support. We resolve pulsatile hemodynamics with a multi-scale computational fluid dynamics model coupled to a Lagrangian scheme tracking 2-5 mm particles for three cannula implantations. Blood is modeled as non-Newtonian. Cerebral flow distribution is altered depending on anastomosis angle and comparison of means embolization rates between steady and unsteady flow models show that unsteady modeling is more accurate even in the full LVAD support case. Intermediate angle implantation yields lowest cerebral embolization incidence of 11% vs 29% for normal and 36% for shallow implantation.
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Affiliation(s)
- Ray Prather
- Department of Mechanical and Aerospace Engineering, University of Central Florida, Orlando, Florida, USA.,Department of Mechanical Engineering, Embry-Riddle Aeronautical University, Daytona Beach, Florida, USA.,Arnold Palmer Children's Hospital, Orlando Health, Orlando, Florida, USA
| | - Eduardo Divo
- Department of Mechanical Engineering, Embry-Riddle Aeronautical University, Daytona Beach, Florida, USA
| | - Alain Kassab
- Department of Mechanical and Aerospace Engineering, University of Central Florida, Orlando, Florida, USA
| | - William DeCampli
- Arnold Palmer Children's Hospital, Orlando Health, Orlando, Florida, USA.,College of Medicine, University of Central Florida, Orlando, Florida, USA
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9
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Prather R, Divo E, Kassab A, DeCampli W. Computational Fluid Dynamics Study of Cerebral Thromboembolism Risk in Ventricular Assist Device Patients: Effects of Pulsatility and Thrombus Origin. J Biomech Eng 2021; 143:091001. [PMID: 33843992 DOI: 10.1115/1.4050819] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Indexed: 11/08/2022]
Abstract
This study investigates the hypothesis that by surgically manipulating the outflow graft (OG) implantation during ventricle assist device placement, it may be possible to reduce the risk of cerebral embolism. We investigate this hypothesis using a computational approach on a patient-specific basis under fully pulsatile hemodynamics with a multiscale computational fluid dynamics model incorporating a coupled Eulerian-Lagrangian scheme that effectively tracks emboli in the fluid domain. Blood is modeled as a non-Newtonian fluid based on the hematocrit level. Preliminary flow analysis shows that depending on the anastomosis angle the left ventricular assist device (LVAD) can enhance the flow to the cerebral circulation by nearly 31%. Z-test results suggest that unsteady-flow modeling ought to be an integral part of any cardiovascular simulation with residual ventricular function. Assuming unsteady-flow conditions, a shallow LVAD outflow graft anastomosis angle is the most optimal if thrombi are released from the aortic-root reducing cerebral embolization incidence to 15.5% and from the ventricle to 17%, while a more pronounced anastomosis angle becomes advantageous when particles originate from the LVAD with an embolization rate of 16.9%. Overall, computations suggest that a pronounced LVAD anastomosis angle is the better implementation. Unsteady modeling is shown to be necessary for the presence of significant antegrade aortic-root flow which induces cyclical flow patterns due to residual pulsatility. On the other hand, depending on thrombus origin and ventricular assist devices (VAD) anastomosis angle there is a strong tradeoff in embolization rates.
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Affiliation(s)
- Ray Prather
- Department of Mechanical and Aerospace Engineering, University of Central Florida, 4000 Central Florida Boulevard, Orlando, FL 32816; Department of Mechanical Engineering, Embry-Riddle Aeronautical University, 600 South Clyde Morris Boulevard, Daytona Beach, FL 32114; Arnold Palmer Children's Hospital, 1222 South Orange Avenue, 92 West Miller Street, Orlando, FL 32806
| | - Eduardo Divo
- Department of Mechanical Engineering, Embry-Riddle Aeronautical University, 600 South Clyde Morris Boulevard, Daytona Beach, FL 32114
| | - Alain Kassab
- Department of Mechanical and Aerospace Engineering, University of Central Florida, 4000 Central Florida Boulevard, Orlando, FL 32816
| | - William DeCampli
- Arnold Palmer Children's Hospital, 1222 South Orange Avenue, Orlando, FL 32806; College of Medicine, University of Central Florida, 6850 Lake Nona Boulevard, Orlando, FL 32827
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Cho SM, Tahsili-Fahadan P, Kilic A, Choi CW, Starling RC, Uchino K. A Comprehensive Review of Risk Factor, Mechanism, and Management of Left Ventricular Assist Device-Associated Stroke. Semin Neurol 2021; 41:411-421. [PMID: 33851393 DOI: 10.1055/s-0041-1726328] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
The use of left ventricular assist devices (LVADs) has been increasing in the last decade, along with the number of patients with advanced heart failure refractory to medical therapy. Ischemic stroke and intracranial hemorrhage remain the leading causes of morbidity and mortality in LVAD patients. Despite the common occurrence and the significant outcome impact, underlying mechanisms and management strategies of stroke in LVAD patients are controversial. In this article, we review our current knowledge on pathophysiology and risk factors of LVAD-associated stroke, outline the diagnostic approach, and discuss treatment strategies.
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Affiliation(s)
- Sung-Min Cho
- Division of Neurocritical Care, Departments of Neurology, Neurosurgery, and Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Pouya Tahsili-Fahadan
- Division of Neurocritical Care, Departments of Neurology, Neurosurgery, and Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland.,Neuroscience Intensive Care Unit, Department of Medicine, Virginia Commonwealth University, Inova Fairfax Medical Campus, Falls Church, Virginia.,Neuroscience Research, Neuroscience and Spine Institute, Inova Fairfax Medical Campus, Falls Church, Virginia
| | - Ahmet Kilic
- Department of Cardiac Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Chun Woo Choi
- Department of Cardiac Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | | | - Ken Uchino
- Neurological Institute, Cleveland Clinic, Cleveland, Ohio
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11
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McElroy M, Kim Y, Niccoli G, Vergallo R, Langford-Smith A, Crea F, Gijsen F, Johnson T, Keshmiri A, White SJ. Identification of the haemodynamic environment permissive for plaque erosion. Sci Rep 2021; 11:7253. [PMID: 33790317 PMCID: PMC8012657 DOI: 10.1038/s41598-021-86501-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 03/11/2021] [Indexed: 02/02/2023] Open
Abstract
Endothelial erosion of atherosclerotic plaques is the underlying cause of approximately 30% of acute coronary syndromes (ACS). As the vascular endothelium is profoundly affected by the haemodynamic environment to which it is exposed, we employed computational fluid dynamic (CFD) analysis of the luminal geometry from 17 patients with optical coherence tomography (OCT)-defined plaque erosion, to determine the flow environment permissive for plaque erosion. Our results demonstrate that 15 of the 17 cases analysed occurred on stenotic plaques with median 31% diameter stenosis (interquartile range 28–52%), where all but one of the adherent thrombi located proximal to, or within the region of maximum stenosis. Consequently, all flow metrics related to elevated flow were significantly increased (time averaged wall shear stress, maximum wall shear stress, time averaged wall shear stress gradient) with a reduction in relative residence time, compared to a non-diseased reference segment. We also identified two cases that did not exhibit an elevation of flow, but occurred in a region exposed to elevated oscillatory flow. Our study demonstrates that the majority of OCT-defined erosions occur where the endothelium is exposed to elevated flow, a haemodynamic environment known to evoke a distinctive phenotypic response in endothelial cells.
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Affiliation(s)
- Michael McElroy
- Department of Mechanical, Aerospace and Civil Engineering (MACE), The University of Manchester, Manchester, M13 9PL, UK
| | - Yongcheol Kim
- Division of Cardiology, Department of Internal Medicine, Yonsei University College of Medicine and Cardiovascular Center, Yongin Severance Hospital, Yongin, Republic of Korea
| | - Giampaolo Niccoli
- Division of Cardiology, Department of Medicine and Surgery, University of Parma, Parma, Italy
| | - Rocco Vergallo
- Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy.,Universita' Cattolica del Sacro Cuore, Rome, Italy
| | | | - Filippo Crea
- Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy.,Universita' Cattolica del Sacro Cuore, Rome, Italy
| | - Frank Gijsen
- Department of Cardiology, Erasmus Medical Centre, Rotterdam, The Netherlands.,Department of Biomechanical Engineering, TUDelft, Delft, The Netherlands
| | - Thomas Johnson
- Department of Cardiology, Bristol Heart Institute, University Hospitals Bristol and Weston NHS Foundation Trust, Upper Maudlin St., Bristol, BS2 8HW, UK
| | - Amir Keshmiri
- Department of Mechanical, Aerospace and Civil Engineering (MACE), The University of Manchester, Manchester, M13 9PL, UK
| | - Stephen J White
- Department of Life Sciences, Manchester Metropolitan University, Manchester, M1 5GD, UK.
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12
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Amili O, MacIver R, Coletti F. Magnetic Resonance Imaging Based Flow Field and Lagrangian Particle Tracking From a Left Ventricular Assist Device. J Biomech Eng 2020; 142:021007. [PMID: 31150534 DOI: 10.1115/1.4043939] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Indexed: 11/08/2022]
Abstract
This study explores the optimal left ventricular assist device (LVAD) cannula outflow configuration in a patient-specific replica of the aorta. The volumetric velocity field is measured using phase-contrast magnetic resonance imaging (PC-MRI) under a physiologically relevant steady flow. The effect of the LVAD outflow graft insertion site and anastomosis angle on the transport of embolic particles to cranial vessels is studied by solving the particle equation of motion for spheres in the range of 0.1-1.0 mm using the measured three-dimensional (3D) velocity field. Results show that for a given aorta anatomy, it is possible to design the cannula graft location and terminal curvature so that the probability of embolic transport to the cranial vessels is significantly minimized. This is particularly important since the complex flow pattern in each cannula case affects the embolic trajectories differently, and hence the common assumption that particles distribute by the volumetric flow division does not hold.
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Affiliation(s)
- Omid Amili
- Department of Aerospace Engineering and Mechanics, University of Minnesota, Minneapolis, MN 55455
| | - Robroy MacIver
- Children's Heart Clinic, Children's Hospitals and Clinics of Minnesota, Minneapolis, MN 55404
| | - Filippo Coletti
- St. Anthony Falls Laboratory, Department of Aerospace Engineering and Mechanics, University of Minnesota, Minneapolis, MN 55455
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13
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Marsh LMM, Barbour MC, Chivukula VK, Chassagne F, Kelly CM, Levy SH, Kim LJ, Levitt MR, Aliseda A. Platelet Dynamics and Hemodynamics of Cerebral Aneurysms Treated with Flow-Diverting Stents. Ann Biomed Eng 2019; 48:490-501. [PMID: 31549329 DOI: 10.1007/s10439-019-02368-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Accepted: 09/13/2019] [Indexed: 02/06/2023]
Abstract
Flow-diverting stents (FDS) are used to treat cerebral aneurysms. They promote the formation of a stable thrombus within the aneurysmal sac and, if successful, isolate the aneurysmal dome from mechanical stresses to prevent rupture. Platelet activation, a mechanism necessary for thrombus formation, is known to respond to biomechanical stimuli, particularly to the platelets' residence time and shear stress exposure. Currently, there is no reliable method for predicting FDS treatment outcomes, either a priori or after the procedure. Eulerian computational fluid dynamic (CFD) studies of aneurysmal flow have searched for predictors of endovascular treatment outcome; however, the hemodynamics of thrombus formation cannot be fully understood without considering the platelets' trajectories and their mechanics-triggered activation. Lagrangian analysis of the fluid mechanics in the aneurysmal vasculature provides novel metrics by tracking the platelets' residence time (RT) and shear history (SH). Eulerian and Lagrangian parameters are compared for 19 patient-specific cases, both pre- and post-treatment, to assess the degree of change caused by the FDS and subsequent treatment efficacy.
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Affiliation(s)
- Laurel M M Marsh
- Mechanical Engineering, University of Washington, 4000 15th Ave NE, Box 352600, Seattle, WA, 98195, USA
| | - Michael C Barbour
- Mechanical Engineering, University of Washington, 4000 15th Ave NE, Box 352600, Seattle, WA, 98195, USA
| | - Venkat Keshav Chivukula
- Mechanical Engineering, University of Washington, 4000 15th Ave NE, Box 352600, Seattle, WA, 98195, USA
| | - Fanette Chassagne
- Mechanical Engineering, University of Washington, 4000 15th Ave NE, Box 352600, Seattle, WA, 98195, USA
| | - Cory M Kelly
- Neurological Surgery, University of Washington, Seattle, WA, USA.,Stroke & Applied NeuroScience Center, University of Washington, Seattle, WA, USA
| | - Samuel H Levy
- Neurological Surgery, University of Washington, Seattle, WA, USA.,Stroke & Applied NeuroScience Center, University of Washington, Seattle, WA, USA
| | - Louis J Kim
- Neurological Surgery, University of Washington, Seattle, WA, USA.,Stroke & Applied NeuroScience Center, University of Washington, Seattle, WA, USA.,Radiology, University of Washington, Seattle, WA, USA
| | - Michael R Levitt
- Mechanical Engineering, University of Washington, 4000 15th Ave NE, Box 352600, Seattle, WA, 98195, USA.,Neurological Surgery, University of Washington, Seattle, WA, USA.,Stroke & Applied NeuroScience Center, University of Washington, Seattle, WA, USA.,Radiology, University of Washington, Seattle, WA, USA
| | - Alberto Aliseda
- Mechanical Engineering, University of Washington, 4000 15th Ave NE, Box 352600, Seattle, WA, 98195, USA. .,Neurological Surgery, University of Washington, Seattle, WA, USA. .,Stroke & Applied NeuroScience Center, University of Washington, Seattle, WA, USA.
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14
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Malone F, McCarthy E, Delassus P, Buhk JH, Fiehler J, Morris L. Embolus Analog Trajectory Paths Under Physiological Flowrates Through Patient-Specific Aortic Arch Models. J Biomech Eng 2019; 141:2734765. [DOI: 10.1115/1.4043832] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Indexed: 01/10/2023]
Abstract
Atrial fibrillation (AF) is the most common irregular heartbeat among the world's population and is a major contributor to cardiogenic embolisms and acute ischemic stroke (AIS). However, the role AF flow plays in the trajectory paths of cardiogenic emboli has not been experimentally investigated. A physiological simulation system was designed to analyze the trajectory patterns of bovine embolus analogs (EAs) (n = 720) through four patient-specific models, under three flow conditions: steady flow, normal pulsatile flow, and AF pulsatile flow. It was seen that EA trajectory paths were proportional to the percentage flowrate split of 25–31% along the branching vessels. Overall, AF flow conditions increased trajectories through the left- (LCCA) and right (RCCA)-common carotid artery by 25% with respect to normal pulsatile flow. There was no statistical difference in the distribution of clot trajectories when the clot was released from the right, left, or anterior positions. Significantly, more EAs traveled through the brachiocephalic trunk (BCT) than through the LCCA or the left subclavian. Yet of the EAs that traveled through the common carotid arteries, there was a greater affiliation toward the LCCA compared to the RCCA (p < 0.05).
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Affiliation(s)
- F. Malone
- GMedTech, Department of Mechanical and Industrial Engineering, Galway-Mayo Institute of Technology, Galway H91 T8NW, Ireland e-mail:
| | - E. McCarthy
- GMedTech, Department of Mechanical and Industrial Engineering, Galway-Mayo Institute of Technology, Galway H91 T8NW, Ireland
| | - P. Delassus
- GMedTech, Department of Mechanical and Industrial Engineering, Galway-Mayo Institute of Technology, Galway H91 T8NW, Ireland
| | - J. H. Buhk
- Department of Diagnostic and Interventional Neuroradiology, University Medical Center Hamburg-Eppendorf, Martinistr. 52, Hamburg 20246, Germany
| | - J. Fiehler
- Department of Diagnostic and Interventional Neuroradiology, University Medical Center Hamburg-Eppendorf, Martinistr. 52, Hamburg 20246, Germany
| | - L. Morris
- GMedTech, Department of Mechanical and Industrial Engineering, Galway-Mayo Institute of Technology, Galway H91 T8NW, Ireland e-mail:
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Thaker R, Araujo-Gutierrez R, Marcos-Abdala HG, Agrawal T, Fida N, Kassi M. Innovative Modeling Techniques and 3D Printing in Patients with Left Ventricular Assist Devices: A Bridge from Bench to Clinical Practice. J Clin Med 2019; 8:E635. [PMID: 31075841 PMCID: PMC6572374 DOI: 10.3390/jcm8050635] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 04/24/2019] [Accepted: 05/01/2019] [Indexed: 02/07/2023] Open
Abstract
Left ventricular assist devices (LVAD) cause altered flow dynamics that may result in complications such as stroke, pump thrombosis, bleeding, or aortic regurgitation. Understanding altered flow dynamics is important in order to develop more efficient and durable pump configurations. In patients with LVAD, hemodynamic assessment is limited to imaging techniques such as echocardiography which precludes detailed assessment of fluid dynamics. In this review article, we present some innovative modeling techniques that are often used in device development or for research purposes, but have not been utilized clinically. Computational fluid dynamic (CFD) modeling is based on computer simulations and particle image velocimetry (PIV) employs ex vivo models that helps study fluid characteristics such as pressure, shear stress, and velocity. Both techniques may help elaborate our understanding of complications that occur with LVAD and could be potentially used in the future to troubleshoot LVAD-related alarms. These techniques coupled with 3D printing may also allow for patient-specific device implants, lowering the risk of complications increasing device durability.
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Affiliation(s)
- Rishi Thaker
- Touro College of Osteopathic Medicine, Middletown, New York, NY 10940, USA.
| | - Raquel Araujo-Gutierrez
- Houston Methodist DeBakey Heart & Vascular Center, Houston Methodist Hospital, Houston, TX 77030, USA.
| | - Hernan G Marcos-Abdala
- Houston Methodist DeBakey Heart & Vascular Center, Houston Methodist Hospital, Houston, TX 77030, USA.
| | - Tanushree Agrawal
- Department of Internal Medicine, Houston Methodist Hospital, Houston, TX 77030, USA.
| | - Nadia Fida
- Houston Methodist DeBakey Heart & Vascular Center, Houston Methodist Hospital, Houston, TX 77030, USA.
| | - Mahwash Kassi
- Houston Methodist DeBakey Heart & Vascular Center, Houston Methodist Hospital, Houston, TX 77030, USA.
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16
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17
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Selmi M, Chiu WC, Chivukula VK, Melisurgo G, Beckman JA, Mahr C, Aliseda A, Votta E, Redaelli A, Slepian MJ, Bluestein D, Pappalardo F, Consolo F. Blood damage in Left Ventricular Assist Devices: Pump thrombosis or system thrombosis? Int J Artif Organs 2018; 42:113-124. [PMID: 30354870 DOI: 10.1177/0391398818806162] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Introduction: Despite significant technical advancements in the design and manufacture of Left Ventricular Assist Devices, post-implant thrombotic and thromboembolic complications continue to affect long-term outcomes. Previous efforts, aimed at optimizing pump design as a means of reducing supraphysiologic shear stresses generated within the pump and associated prothrombotic shear-mediated platelet injury, have only partially altered the device hemocompatibility. Methods: We examined hemodynamic mechanisms that synergize with hypershear within the pump to contribute to the thrombogenic potential of the overall Left Ventricular Assist Device system. Results: Numerical simulations of blood flow in differing regions of the Left Ventricular Assist Device system, that is the diseased native left ventricle, the pump inflow cannula, the impeller, the outflow graft and the anastomosed downstream aorta, reveal that prothrombotic hemodynamic conditions might occur at these specific sites. Furthermore, we show that beyond hypershear, additional hemodynamic abnormalities exist within the pump, which may elicit platelet activation, such as recirculation zones and stagnant platelet trajectories. We also provide evidences that particular Left Ventricular Assist Device implantation configurations and specific post-implant patient management strategies, such as those allowing aortic valve opening, are more hemodynamically favorable and reduce the thrombotic risk. Conclusion: We extend the perspective of pump thrombosis secondary to the supraphysiologic shear stress environment of the pump to one of Left Ventricular Assist Device system thrombosis, raising the importance of comprehensive characterization of the different prothrombotic risk factors of the total system as the target to achieve enhanced hemocompatibility and improved clinical outcomes.
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Affiliation(s)
- Matteo Selmi
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milano, Italy
- Department of Surgery, Division of Cardiac Surgery, Università di Verona, Verona, Italy
| | - Wei-Che Chiu
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA
| | | | - Giulio Melisurgo
- Anesthesia and Cardiothoracic Intensive Care, San Raffaele Scientific Institute, Milano, Italy
| | | | - Claudius Mahr
- Division of Cardiology, University of Washington, Seattle, WA, USA
| | - Alberto Aliseda
- Department of Mechanical Engineering, University of Washington, Seattle, WA, USA
| | - Emiliano Votta
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milano, Italy
| | - Alberto Redaelli
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milano, Italy
| | - Marvin J Slepian
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA
- Departments of Medicine and Biomedical Engineering, The University of Arizona, Tucson, AZ, USA
| | - Danny Bluestein
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA
| | - Federico Pappalardo
- Anesthesia and Cardiothoracic Intensive Care, San Raffaele Scientific Institute, Milano, Italy
- Advanced Heart Failure and Mechanical Circulatory Support Program, San Raffaele Scientific Institute, Milano, Italy
- Università Vita-Salute San Raffaele, Milano, Italy
| | - Filippo Consolo
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milano, Italy
- Advanced Heart Failure and Mechanical Circulatory Support Program, San Raffaele Scientific Institute, Milano, Italy
- Università Vita-Salute San Raffaele, Milano, Italy
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18
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Abstract
Treatment of end-stage heart failure includes cardiac transplantation or ventricular assist device (VAD) therapy. Although increasingly prevalent, current VAD therapy has inherent complications, including thrombosis. Studies have demonstrated that VAD implantation alters intracardiac blood flow, creating areas of stagnation that predispose to thrombus formation. Two potential surgical configurations exist for VAD implantation: through the apical or diaphragmatic surfaces of the heart. We hypothesized that diaphragmatic implantation causes more stagnation than apical implantation. We also hypothesized that intermittent aortic valve (AV) opening reduces stagnation of blood inside the left ventricle (LV) when compared with a closed AV. To test these hypotheses, a human LV geometry was recreated in silico and a VAD inflow cannula was virtually implanted in each configuration. A computational indicator-dilution study was conducted where "virtually dyed blood" was washed out of the LV by injecting blood with no dye. Simulations demonstrated a substantial reduction in stagnation with intermittent AV opening. In addition, virtual dye was cleared slightly faster in the apical configuration. Simulations from our study demonstrate the clinical importance of VAD management to allow intermittent opening of the AV to prevent subvalvular stagnation, and also suggests that apical configuration might be more hemodynamically favorable.
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19
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Loyaga-Rendon RY, Jani M, Fermin D, McDermott JK, Vancamp D, Lee S. Prevention and Treatment of Thrombotic and Hemorrhagic Complications in Patients Supported by Continuous-Flow Left Ventricular Assist Devices. Curr Heart Fail Rep 2018; 14:465-477. [PMID: 29075955 DOI: 10.1007/s11897-017-0367-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
PURPOSE OF REVIEW The purpose of this review is to describe the current knowledge in prevention and treatment of thrombotic (pump thrombosis and ischemic stroke) and bleeding (gastrointestinal and hemorrhagic stroke) complications in patients supported by continuous-flow left ventricular assist devices (CF-LVAD). RECENT FINDINGS Left ventricular assist devices (LVADs) are now widely used for the management of end-stage heart failure. Unfortunately, in spite of the indisputable positive impact LVADs have on patients, the frequency and severity of complications are limitations of this therapy. Stroke, pump thrombosis, and gastrointestinal bleeding are among the most serious and frequent complications in these patients. The balance between hemorrhagic and thrombotic complications in patients supported with CF-LVAD is difficult as most patients do not necessarily fit a "bleeder" or a "clotter" profile but rather move from one side to the other of the thrombotic/bleeding spectrum. Further research is necessary to better understand the risk factors and mechanisms involved in the development of these complications.
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Affiliation(s)
- Renzo Y Loyaga-Rendon
- Advanced Heart Failure and Heart Transplantation Section, Spectrum Health, 330 Barclay Avenue NE, Suite 200, MC258, Grand Rapids, MI, 49503, USA.
| | - Milena Jani
- Advanced Heart Failure and Heart Transplantation Section, Spectrum Health, 330 Barclay Avenue NE, Suite 200, MC258, Grand Rapids, MI, 49503, USA
| | - David Fermin
- Advanced Heart Failure and Heart Transplantation Section, Spectrum Health, 330 Barclay Avenue NE, Suite 200, MC258, Grand Rapids, MI, 49503, USA
| | - Jennifer K McDermott
- Advanced Heart Failure and Heart Transplantation Section, Spectrum Health, 330 Barclay Avenue NE, Suite 200, MC258, Grand Rapids, MI, 49503, USA
| | - Diane Vancamp
- Advanced Heart Failure and Heart Transplantation Section, Spectrum Health, 330 Barclay Avenue NE, Suite 200, MC258, Grand Rapids, MI, 49503, USA
| | - Sangjin Lee
- Advanced Heart Failure and Heart Transplantation Section, Spectrum Health, 330 Barclay Avenue NE, Suite 200, MC258, Grand Rapids, MI, 49503, USA
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20
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Aliseda A, Chivukula VK, McGah P, Prisco AR, Beckman JA, Garcia GJ, Mokadam NA, Mahr C. LVAD Outflow Graft Angle and Thrombosis Risk. ASAIO J 2017; 63:14-23. [PMID: 28033200 PMCID: PMC5201113 DOI: 10.1097/mat.0000000000000443] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
This study quantifies thrombogenic potential (TP) of a wide range of left ventricular assist device (LVAD) outflow graft anastomosis angles through state-of-the-art techniques: 3D imaged-based patient-specific models created via virtual surgery and unsteady computational fluid dynamics with Lagrangian particle tracking. This study aims at clarifying the influence of a single parameter (outflow graft angle) on the thrombogenesis associated with flow patterns in the aortic root after LVAD implantation. This is an important and poorly-understood aspect of LVAD therapy, because several studies have shown strong inter and intrapatient thrombogenic variability and current LVAD implantation strategies do not incorporate outflow graft angle optimization. Accurate platelet-level investigation, enabled by statistical treatment of outliers in Lagrangian particle tracking, demonstrates a strong influence of outflow graft anastomoses angle on thrombogenicity (platelet residence times and activation state characterized by shear stress accumulation) with significantly reduced TP for acutely-angled anastomosed outflow grafts. The methodology presented in this study provides a device-neutral platform for conducting comprehensive thrombogenicity evaluation of LVAD surgical configurations, empowering optimal patient-focused surgical strategies for long-term treatment and care for advanced heart failure patients.
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Affiliation(s)
- Alberto Aliseda
- Department of Mechanical Engineering, University of Washington, Seattle, WA, USA
| | | | - Patrick McGah
- Department of Mechanical Engineering, University of Washington, Seattle, WA, USA
| | - Anthony R. Prisco
- Biotechnology and Bioengineering Center, Medical College of Wisconsin, Milwaukee, WI, USA
| | | | - Guilherme J.M. Garcia
- Biotechnology and Bioengineering Center, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Nahush A Mokadam
- Division of Cardiothoracic Surgery, University of Washington, Seattle, WA, USA
| | - Claudius Mahr
- Division of Cardiology, University of Washington, Seattle, WA, USA
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21
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Choi HW, Luo T, Navia JA, Kassab GS. Role of Aortic Geometry on Stroke Propensity based on Simulations of Patient-Specific Models. Sci Rep 2017; 7:7065. [PMID: 28765648 PMCID: PMC5539283 DOI: 10.1038/s41598-017-06681-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Accepted: 06/16/2017] [Indexed: 12/01/2022] Open
Abstract
Stroke is a life threatening event that is expected to more than double over the next 40 years. Atrial fibrillation (AF) has been reported as a strong independent risk factor for stroke. We have previously shown that a hemodynamic perturbation by AF or reduced cardiac output and cycle length may have a significant impact on clot trajectory and thus embolic stroke propensity through the left common carotid artery using an idealized aortic arch model. Here, we show the dependence of flow patterns and hence stroke propensity on geometry of patient-specific aortas. We performed computational fluid dynamics (CFD) simulations to determine the variations of AF-induced stroke propensity over various image-based patient-dependent aorta models. The results demonstrated that curvature pattern of aorta can play a determinant role in AF-induced stroke propensity alteration. Specifically, it was shown that the hemodynamic perturbation by AF considered led to substantial increase in stroke propensity (i.e., 2.5~3.8 fold elevation) for lower curvature angle <90° while the changes in stroke propensity by AF are negligible for higher curvature angle >90°. The present simulations suggest that aortic arch curvature is an important risk factor for embolic stroke which should be tested in future clinical trials.
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Affiliation(s)
- Hyo Won Choi
- The California Medical Innovations Institute, San Diego, California, United States of America
| | - Tong Luo
- The California Medical Innovations Institute, San Diego, California, United States of America
| | - Jose A Navia
- Department of Surgery, Austral University, Buenos Aires, Argentina
| | - Ghassan S Kassab
- The California Medical Innovations Institute, San Diego, California, United States of America.
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22
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Effect of Outflow Graft Size on Flow in the Aortic Arch and Cerebral Blood Flow in Continuous Flow Pumps: Possible Relevance to Strokes. ASAIO J 2016; 63:144-149. [PMID: 28033184 DOI: 10.1097/mat.0000000000000507] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
One of the most devastating complications of continuous flow left ventricular devices (CFLVADS) is stroke, with a higher incidence in HeartWare Ventricular Assist Device (HVAD) as compared with HEARTMATE II. The reason for the observed difference in stroke rates is unclear. Because outflow graft diameters are different, we hypothesized that this could contribute to the difference in stroke rates. A computational fluid-structure interaction model was created from the computed tomography (CT) scan of a patient. Pressures were used as the boundary condition and the flow through the cerebral vessels was derived as outputs. Flow into the innominate artery was very sensitive to the anastomosis angle for a 10 mm as compared with a 14 mm graft, with the net innominate flow severely compromised with a 10 mm graft at 45° angle. Aortic insufficiency seems to affect cerebral blood flow nonlinearly with an 80% decrease at certain angles of outflow graft anastomosis. Arterial return in to the arch through a narrow graft has important jet effects and results in significant flow perturbations in the aortic arch and cerebral vessels and stasis. A 10 mm graft is more sensitive to angle of insertion than a 14 mm graft. Under some conditions, serious hypoperfusion of the innominate artery is possible. Aortic incompetence results in significant decrease of cerebral blood flow. No stasis was found in the pulsatile flow compared with LVAD flow.
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23
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Aycock KI, Campbell RL, Manning KB, Craven BA. A resolved two-way coupled CFD/6-DOF approach for predicting embolus transport and the embolus-trapping efficiency of IVC filters. Biomech Model Mechanobiol 2016; 16:851-869. [DOI: 10.1007/s10237-016-0857-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Accepted: 11/15/2016] [Indexed: 12/27/2022]
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24
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Zhang Y, Gao B, Yu C. The hemodynamic effects of the LVAD outflow cannula location on the thrombi distribution in the aorta: A primary numerical study. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2016; 133:217-227. [PMID: 27393812 DOI: 10.1016/j.cmpb.2016.05.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Revised: 05/06/2016] [Accepted: 05/31/2016] [Indexed: 06/06/2023]
Abstract
Although a growing number of patients undergo LVAD implantation for heart failure treatment, thrombi are still the devastating complication for patients who used LVAD. LVAD outflow cannula location and thrombi generation sources were hypothesized to affect the thrombi distribution in the aorta. To test this hypothesis, numerical studies were conducted by using computational fluid dynamic (CFD) theory. Two anastomotic configurations, in which the LVAD outflow cannula is anastomosed to the anterior and lateral ascending aortic wall (named as anterior configurations and lateral configurations, respectively), are designed. The particles, whose sized are same as those of thrombi, are released at the LVAD output cannula and the aortic valve (named as thrombiP and thrombiL, respectively) to calculate the distribution of thrombi. The simulation results demonstrate that the thrombi distribution in the aorta is significantly affected by the LVAD outflow cannula location. In anterior configuration, the thrombi probability of entering into the three branches is 23.60%, while that in lateral configuration is 36.68%. Similarly, in anterior configuration, the thrombi probabilities of entering into brachiocephalic artery, left common carotid artery and left subclavian artery, is 8.51%, 9.64%, 5.45%, respectively, while that in lateral configuration it is 11.39%, 3.09%, 22.20% respectively. Moreover, the origins of thrombi could affect their distributions in the aorta. In anterior configuration, the thrombiP has a lower probability to enter into the three branches than thrombiL (12% vs. 25%). In contrast, in lateral configuration, the thrombiP has a higher probability to enter into the three branches than thrombiL (47% vs. 35%). In brief, the LVAD outflow cannula location significantly affects the distribution of thrombi in the aorta. Thus, in the clinical practice, the selection of outflow location of LVAD and the risk of thrombi formed in the left ventricle should be paid more attention than before.
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Affiliation(s)
- Yage Zhang
- School of Life Science and BioEngineering, Beijing University of Technology, Beijing 100124, China
| | - Bin Gao
- School of Life Science and BioEngineering, Beijing University of Technology, Beijing 100124, China
| | - Chang Yu
- School of Life Science and BioEngineering, Beijing University of Technology, Beijing 100124, China.
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25
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Zhang Q, Gao B, Chang Y. Effect of Different Rotational Directions of BJUT-II VAD on Aortic Swirling Flow Characteristics: A Primary Computational Fluid Dynamics Study. Med Sci Monit 2016; 22:2576-88. [PMID: 27440399 PMCID: PMC4966492 DOI: 10.12659/msm.899313] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Background The BJUT-II VAD is a novel left ventricular assist device (LVAD), which is thought to have significant effects on the characteristics of aortic swirling flow. However, the precise mechanism of the rotational direction of BJTU-II VAD in the aortic swirling flow is unclear. Material/Methods A patient-specific aortic geometric model was reconstructed based on the CT data. Three pump’s output flow profiles with varied rotational direction, termed “counterclockwise”, “flat profile”, and “clockwise”, were used as the boundary conditions. The helicity density, area-weighted average of helicity density (Ha), localized normalized helicity (LNH), wall shear stress (WSS), and WSS spatial gradient (WSSG) were calculated to evaluate the swirling flow characteristics in the aorta. Results The results demonstrated that the swirling flow characteristics in the aorta and 3 branches are directly affected by the output blood flow of BJUT-II VAD. In the aortic arch, the helicity density, supported by the clockwise case, achieved the highest value. In the 3 branches, the flat profile case achieved the highest helicity density, whereas the maximum WSS and WSSG generated by clockwise case were lower than in other cases. Conclusions The outflow of the BJUT-II VAD has significant effects on the aortic hemodynamics and swirling flow characteristics. The helical blood profiles can enhance the strength of aortic swirling flow, and reduce the areas of low WSS and WSSG regions. The clockwise case may have a benefit for preventing development of atherosclerosis in the aorta.
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Affiliation(s)
- Qi Zhang
- School of Life Science and BioEngineering, Beijing University of Technology, Beijing, China (mainland)
| | - Bin Gao
- School of Life Science and BioEngineering, Beijing University of Technology, Beijing, China (mainland)
| | - Yu Chang
- School of Life Science and BioEngineering, Beijing University of Technology, Beijing, China (mainland)
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26
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Klotz S, Meyer-Saraei R, Frydrychowicz A, Scharfschwerdt M, Putman LM, Halder S, Sievers HH. Proposing a novel technique to exclude the left ventricle with an assist device: insights from 4-dimensional flow magnetic resonance imaging. Eur J Cardiothorac Surg 2016; 50:439-45. [DOI: 10.1093/ejcts/ezw092] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 02/10/2016] [Indexed: 11/13/2022] Open
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27
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Mazzitelli R, Boyle F, Murphy E, Renzulli A, Fragomeni G. Numerical prediction of the effect of aortic Left Ventricular Assist Device outflow-graft anastomosis location. Biocybern Biomed Eng 2016. [DOI: 10.1016/j.bbe.2016.01.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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28
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Bhimaraj A, Uribe C, Suarez EE. Physiological impact of continuous flow on end-organ function: clinical implications in the current era of left ventricular assist devices. Methodist Debakey Cardiovasc J 2015; 11:12-7. [PMID: 25793024 DOI: 10.14797/mdcj-11-1-12] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The clinical era of continuous-flow left ventricular assist devices has debunked many myths about the dire need of a pulse for human existence. While this therapy has been documented to provide a clear survival benefit in end-stage heart failure patients, we are now faced with certain morbidity challenges that as of yet have no easy mechanistic physiological explanation. The effect of physiological changes on end-organ function in patients supported by continuous-flow ventricular assist devices may offer insight into some of these morbidities. We therefore present a review of current evidence documenting the impact of continuous flow on end-organ function.
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Affiliation(s)
- Arvind Bhimaraj
- Houston Methodist DeBakey Heart & Vascular Center, Houston Methodist Hospital, Houston, Texas
| | - Cesar Uribe
- Houston Methodist DeBakey Heart & Vascular Center, Houston Methodist Hospital, Houston, Texas
| | - Erick E Suarez
- Houston Methodist DeBakey Heart & Vascular Center, Houston Methodist Hospital, Houston, Texas
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29
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Farag MB, Karmonik C, Rengier F, Loebe M, Karck M, von Tengg-Kobligk H, Ruhparwar A, Partovi S. Review of recent results using computational fluid dynamics simulations in patients receiving mechanical assist devices for end-stage heart failure. Methodist Debakey Cardiovasc J 2015; 10:185-9. [PMID: 25574347 DOI: 10.14797/mdcj-10-3-185] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Many end-stage heart failure patients are not eligible to undergo heart transplantation due to organ shortage, and even those under consideration for transplantation might suffer long waiting periods. A better understanding of the hemodynamic impact of left ventricular assist devices (LVAD) on the cardiovascular system is therefore of great interest. Computational fluid dynamics (CFD) simulations give the opportunity to study the hemodynamics in this patient population using clinical imaging data such as computed tomographic angiography. This article reviews a recent study series involving patients with pulsatile and constant-flow LVAD devices in which CFD simulations were used to qualitatively and quantitatively assess blood flow dynamics in the thoracic aorta, demonstrating its potential to enhance the information available from medical imaging.
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Affiliation(s)
| | - Christof Karmonik
- Houston Methodist Research Institute, Houston Methodist Hospital, Houston, Texas
| | | | - Matthias Loebe
- Houston Methodist Research Institute, Houston Methodist Hospital, Houston, Texas
| | | | - Hendrik von Tengg-Kobligk
- Institute for Diagnostic, Interventional and Pediatric Radiology, Inselspital Bern, Bern, Switzerland
| | | | - Sasan Partovi
- University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio
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Computational fluid dynamic study of hemodynamic effects on aortic root blood flow of systematically varied left ventricular assist device graft anastomosis design. J Thorac Cardiovasc Surg 2015; 150:696-704. [DOI: 10.1016/j.jtcvs.2015.05.034] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Revised: 04/10/2015] [Accepted: 05/09/2015] [Indexed: 11/23/2022]
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31
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Nguyen T, Argueta-Morales IR, Guimond S, Clark W, Ceballos A, Osorio R, Divo EA, De Campli WM, Kassab AJ. Computational analysis of pediatric ventricular assist device implantation to decrease cerebral particulate embolization. Comput Methods Biomech Biomed Engin 2015. [PMID: 26214744 DOI: 10.1080/10255842.2015.1062478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Stroke is the most devastating complication after ventricular assist device (VAD) implantation with a 19% incidence and 65% mortality in the pediatric population. Current pediatric VAD technology and anticoagulation strategies alone are suboptimal. VAD implantation assisted by computational methods (CFD) may contribute reducing the risk of cerebral embolization. Representative three-dimensional aortic arch models of an infant and a child were generated. An 8 mm VAD outflow-graft (VAD-OG) anastomosed to the aorta was rendered and CFD was applied to study blood flow patterns. Particle tracks, originating in the VAD, were computed with a Lagrangian phase model and the percentage of particles entering the cerebral vessels was calculated. Eight implantation configurations (infant = 5 and child = 3) and 5 particle sizes (0.5, 1, 2, 3, and 4 mm) were considered. For the infant model, percentage of particles entering the cerebral vessels ranged from 15% for a VAD-OG anastomosed at 90° to the aorta, to 31% for 30° VAD-OG anastomosis (overall percentages: X(2) = 10,852, p < 0.0001). For the child model, cerebral embolization ranged from 9% for the 30° VAD-OG anastomosis to 15% for the 60° anastomosis (overall percentages: χ(2) = 10,323, p < 0.0001). Using detailed CFD calculations, we demonstrate that the risk of stroke depends significantly on the VAD implantation geometry. In turn, the risk probably depends on patient-specific anatomy. CFD can be used to optimize VAD implantation geometry to minimize stroke risk.
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Affiliation(s)
- ThuyTien Nguyen
- a Department of Mechanical and Aerospace Engineering, College of Engineering and Computer Science, University of Central Florida , Orlando , FL , USA
| | - I Ricardo Argueta-Morales
- b The Heart Center, Cardiothoracic Surgery , Arnold Palmer Hospital for Children , Orlando , FL , USA
| | - Stephen Guimond
- a Department of Mechanical and Aerospace Engineering, College of Engineering and Computer Science, University of Central Florida , Orlando , FL , USA
| | - William Clark
- a Department of Mechanical and Aerospace Engineering, College of Engineering and Computer Science, University of Central Florida , Orlando , FL , USA
| | - Andres Ceballos
- a Department of Mechanical and Aerospace Engineering, College of Engineering and Computer Science, University of Central Florida , Orlando , FL , USA
| | - Ruben Osorio
- a Department of Mechanical and Aerospace Engineering, College of Engineering and Computer Science, University of Central Florida , Orlando , FL , USA
| | - Eduardo A Divo
- a Department of Mechanical and Aerospace Engineering, College of Engineering and Computer Science, University of Central Florida , Orlando , FL , USA.,c Department of Mechanical Engineering , Embry-Riddle Aeronautical University , Daytona Beach , FL , USA
| | - William M De Campli
- a Department of Mechanical and Aerospace Engineering, College of Engineering and Computer Science, University of Central Florida , Orlando , FL , USA.,b The Heart Center, Cardiothoracic Surgery , Arnold Palmer Hospital for Children , Orlando , FL , USA.,d College of Medicine , University of Central Florida , Orlando , FL , USA
| | - Alain J Kassab
- a Department of Mechanical and Aerospace Engineering, College of Engineering and Computer Science, University of Central Florida , Orlando , FL , USA
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Comparison Between Bench-Top and Computational Modelling of Cerebral Thromboembolism in Ventricular Assist Device Circulation. Cardiovasc Eng Technol 2015; 6:242-55. [DOI: 10.1007/s13239-015-0230-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 06/08/2015] [Indexed: 12/13/2022]
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Choi HW, Navia JA, Kassab GS. Thrombus deflector stent for stroke prevention: A simulation study. J Biomech 2015; 48:1789-95. [PMID: 26049978 DOI: 10.1016/j.jbiomech.2015.05.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Revised: 05/05/2015] [Accepted: 05/06/2015] [Indexed: 11/29/2022]
Abstract
Atrial fibrillation (AF) is a dysfunction of heart rhythm and represents an increased predisposition to ischemic stroke in AF patients. It has been shown that the AF-induced hemodynamic conditions may contribute to the increased embolic propensity through the carotid arteries. We simulated a stroke-prevention device with a unique strut structure to deflect the trajectory of a blood clot to the carotid artery. We identified the important determinants of functionality in a device design using computational fluid dynamics simulations. Quantitative assessment of deflection efficacy over various clot dimensions was carried out for the device with different strut configurations under AF flow conditions. The simulations demonstrate that the trajectory of a clot destined to the left common carotid artery (LCCA) can be deflected by a strut-structured device at the LCCA inlet with virtually no change in flow resistance. The deflection efficacy of the device is dependent on the clot properties and strut designs of the device. A configuration of 0.75 mm thick and 0.75 mm distant struts with 50% of surface convexity were found to provide maximum deflection efficacy (e.g., 36% greater deflection efficacy than a flat filter) among the strut structures considered. The results suggest that a deflector stent implanted in the aortic branch may be an effective stroke-prevention device. The present simulations motivate pre-clinical animal studies as well as further studies on patient-specific design of the device that maximize the deflection efficacy while minimizing device safety issues.
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Affiliation(s)
- Hyo Won Choi
- The California Medical Innovations Institute, 11107 Roselle Street, San Diego, CA 92121, United States
| | - Jose A Navia
- Department of Surgery, Austral University, Buenos Aires, Argentina
| | - Ghassan S Kassab
- The California Medical Innovations Institute, 11107 Roselle Street, San Diego, CA 92121, United States.
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Piskin S, Ündar A, Pekkan K. Computational Modeling of Neonatal Cardiopulmonary Bypass Hemodynamics With Full Circle of Willis Anatomy. Artif Organs 2015; 39:E164-75. [DOI: 10.1111/aor.12468] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Senol Piskin
- Department of Mechanical Engineering; Koc University; Istanbul Turkey
| | - Akif Ündar
- Pediatric Cardiovascular Research Center; Department of Pediatrics, Surgery and Bioengineering; Penn State Hershey College of Medicine; Hershey PA USA
| | - Kerem Pekkan
- Department of Mechanical Engineering; Koc University; Istanbul Turkey
- Department of Biomedical Engineering; Carnegie Mellon University; Pittsburgh PA USA
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Hanke JS, Rojas SV, Martens A, Schmitto JD. Minimally invasive left ventricular assist device implantation with outflow graft anastomosis to the innominate artery. J Thorac Cardiovasc Surg 2015; 149:e69-70. [DOI: 10.1016/j.jtcvs.2014.12.066] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 12/14/2014] [Accepted: 12/24/2014] [Indexed: 11/28/2022]
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The study on hemodynamic effect of varied support models of BJUT-II VAD on coronary artery: a primary CFD study. ASAIO J 2014; 60:643-51. [PMID: 25373559 DOI: 10.1097/mat.0000000000000137] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
BJUT-II VAD (Beijing University of Technology ventricular assist device II) is a novel left ventricular assist device. Because of the special connection between the pump and native heart, the hemodynamic effects of BJUT-II VAD on coronary artery are still unclear. Hence, numerical simulations have been conducted to clarify changes in hemodynamic effects of different support modes. A patient-specific left coronary arterial geometric model is reconstructed based on the computed tomography (CT) data. Three support modes, "constant speed mode," "co-pulse mode," and "counter pulse mode," are used in this study. The wall shear stress (WSS), wall shear stress gradient (WSSG), cycle-averaged wall shear stress (avWSS), oscillatory shear index (OSI), and the flow pattern are calculated to evaluate the hemodynamic states of coronary artery. The computational results demonstrate that the hemodynamic states of coronary artery are directly affected by the support modes. The co-pulse modes could achieve the highest blood perfusion (constant speed: 153 ml/min vs. co-pulse: 775 ml/min vs. counter pulse: 140 ml/min) and the highest avWSS (constant speed: 18.1 Pa vs. co-pulse: 42.6 Pa vs. counter pulse: 22.6 Pa). In addition, both the WSS and WSSG at the time of peak blood velocity under the constant speed mode are lower than those under other two support modes. In contrast, the counter pulse mode generates the highest OSI value (constant speed: 0.365 vs. co-pulse: 0.379 vs. counter pulse: 0.426). BJUT-II VAD under co-pulse mode may have benefits for improving coronary perfusion and preventing the development of atherosclerosis; however, the constant speed mode may have benefit for preventing the development of plaque vulnerability.
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Kaufmann TA, Gregory SD, Büsen MR, Tansley GD, Steinseifer U. Development of a Numerical Pump Testing Framework. Artif Organs 2014; 38:783-90. [DOI: 10.1111/aor.12395] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Tim A.S. Kaufmann
- Department of Cardiovascular Engineering; Institute of Applied Medical Engineering; Helmholtz Institute; RWTH-Aachen University; Aachen Germany
| | - Shaun D. Gregory
- School of Medicine; University of Queensland; Brisbane Queensland Australia
- Innovative Cardiovascular Engineering and Technology Laboratory; The Prince Charles Hospital; Brisbane Queensland Australia
| | - Martin R. Büsen
- Department of Cardiovascular Engineering; Institute of Applied Medical Engineering; Helmholtz Institute; RWTH-Aachen University; Aachen Germany
| | - Geoff D. Tansley
- Innovative Cardiovascular Engineering and Technology Laboratory; The Prince Charles Hospital; Brisbane Queensland Australia
- School of Engineering; Griffith University; Southport Queensland Australia
| | - Ulrich Steinseifer
- Department of Cardiovascular Engineering; Institute of Applied Medical Engineering; Helmholtz Institute; RWTH-Aachen University; Aachen Germany
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Lagrangian postprocessing of computational hemodynamics. Ann Biomed Eng 2014; 43:41-58. [PMID: 25059889 DOI: 10.1007/s10439-014-1070-0] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2014] [Accepted: 07/11/2014] [Indexed: 10/25/2022]
Abstract
Recent advances in imaging, modeling, and computing have rapidly expanded our capabilities to model hemodynamics in the large vessels (heart, arteries, and veins). This data encodes a wealth of information that is often under-utilized. Modeling (and measuring) blood flow in the large vessels typically amounts to solving for the time-varying velocity field in a region of interest. Flow in the heart and larger arteries is often complex, and velocity field data provides a starting point for investigating the hemodynamics. This data can be used to perform Lagrangian particle tracking, and other Lagrangian-based postprocessing. As described herein, Lagrangian methods are necessary to understand inherently transient hemodynamic conditions from the fluid mechanics perspective, and to properly understand the biomechanical factors that lead to acute and gradual changes of vascular function and health. The goal of the present paper is to review Lagrangian methods that have been used in post-processing velocity data of cardiovascular flows.
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Marsden AL, Bazilevs Y, Long CC, Behr M. Recent advances in computational methodology for simulation of mechanical circulatory assist devices. WILEY INTERDISCIPLINARY REVIEWS. SYSTEMS BIOLOGY AND MEDICINE 2014; 6:169-88. [PMID: 24449607 PMCID: PMC3947342 DOI: 10.1002/wsbm.1260] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Revised: 11/06/2013] [Accepted: 12/16/2013] [Indexed: 11/07/2022]
Abstract
Ventricular assist devices (VADs) provide mechanical circulatory support to offload the work of one or both ventricles during heart failure. They are used in the clinical setting as destination therapy, as bridge to transplant, or more recently as bridge to recovery to allow for myocardial remodeling. Recent developments in computational simulation allow for detailed assessment of VAD hemodynamics for device design and optimization for both children and adults. Here, we provide a focused review of the recent literature on finite element methods and optimization for VAD simulations. As VAD designs typically fall into two categories, pulsatile and continuous flow devices, we separately address computational challenges of both types of designs, and the interaction with the circulatory system with three representative case studies. In particular, we focus on recent advancements in finite element methodology that have increased the fidelity of VAD simulations. We outline key challenges, which extend to the incorporation of biological response such as thrombosis and hemolysis, as well as shape optimization methods and challenges in computational methodology.
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Affiliation(s)
- Alison L Marsden
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA, USA
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Choi HW, Navia JA, Kassab GS. Stroke propensity is increased under atrial fibrillation hemodynamics: a simulation study. PLoS One 2013; 8:e73485. [PMID: 24039957 PMCID: PMC3764003 DOI: 10.1371/journal.pone.0073485] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Accepted: 07/25/2013] [Indexed: 12/02/2022] Open
Abstract
Atrial fibrillation (AF) is the most common sustained dysfunction in heart rhythm clinically and has been identified as an independent risk factor for stroke through formation and embolization of thrombi. AF is associated with reduced cardiac output and short and irregular cardiac cycle length. Although the effect of AF on cardiac hemodynamic parameters has been reported, it remains unclear how the hemodynamic perturbations affect the potential embolization of blood clots to the brain that can cause stroke. To understand stroke propensity in AF, we performed computer simulations to describe trajectories of blood clots subject to the aortic flow conditions that represent normal heart rhythm and AF. Quantitative assessment of stroke propensity by blood clot embolism was carried out for a range of clot properties (e.g., 2–6 mm in diameter and 0–0.8 m/s ejection speed) under normal and AF flow conditions. The simulations demonstrate that the trajectory of clot is significantly affected by clot properties as well as hemodynamic waveforms which lead to significant variations in stroke propensity. The predicted maximum difference in stroke propensity in the left common carotid artery was shown to be about 60% between the normal and AF flow conditions examined. The results suggest that the reduced cardiac output and cycle length induced by AF can significantly increase the incidence of carotid embolism. The present simulations motivate further studies on patient-specific risk assessment of stroke in AF.
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Affiliation(s)
- Hyo Won Choi
- Department of Biomedical Engineering, Indiana University Purdue University, Indianapolis, Indiana, United States of America
| | - Jose A. Navia
- Department of Surgery, Austral University, Buenos Aires, Argentina
| | - Ghassan S. Kassab
- Department of Biomedical Engineering, Indiana University Purdue University, Indianapolis, Indiana, United States of America
- Department of Surgery, Indiana University Purdue University, Indianapolis, Indiana, United States of America
- Department of Cellular and Integrative Physiology, Indiana University Purdue University, Indianapolis, Indiana, United States of America
- * E-mail:
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Menon PG, Antaki JF, Undar A, Pekkan K. Aortic outflow cannula tip design and orientation impacts cerebral perfusion during pediatric cardiopulmonary bypass procedures. Ann Biomed Eng 2013; 41:2588-602. [PMID: 23817768 DOI: 10.1007/s10439-013-0857-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2013] [Accepted: 06/24/2013] [Indexed: 10/26/2022]
Abstract
Poor perfusion of the aortic arch is a suspected cause for peri- and post-operative neurological complications associated with cardiopulmonary bypass (CPB). High-speed jets from 8 to 10FR pediatric/neonatal cannulae delivering ~1 L/min of blood can accrue sub-lethal hemolytic damage while also subjecting the aorta to non-physiologic flow conditions that compromise cerebral perfusion. Therefore, we emphasize the importance of cannulation strategy and hypothesize engineering better CPB perfusion through a redesigned aortic cannula tip. This study employs computational fluid dynamics to investigate novel diffuser-tipped aortic cannulae for shape sensitivity to cerebral perfusion, in an in silico cross-clamped aortic arch model modeled with fixed outflow resistances. 17 parametrically altered configurations of an 8FR end-hole and several diffuser cone angled tips in combination with jet incidence angles toward or away from the head-neck vessels were studied. Experimental pressure-flow characterizations were also conducted on these cannula tip designs. An 8FR end-hole aortic cannula delivering 1 L/min along the transverse aortic arch was found to give rise to backflow from the brachicephalic artery (BCA), irrespective of angular orientation, for the chosen ascending aortic insertion location. Parametric alteration of the cannula tip to include a diffuser cone angle (tested up to 7°) eliminated BCA backflow for any tested angle of jet incidence. Experiments revealed that a 1 cm long 10° diffuser cone tip demonstrated the best pressure-flow performance improvement in contrast with either an end-hole tip or diffuser cone angles greater than 10°. Performance further improved when the diffuser was preceded by an expanded four-lobe swirl inducer attachment-a novel component. In conclusion, aortic cannula orientation is crucial in determining net head-neck perfusion but precise angulations and insertion-depths are difficult to achieve practically. Altering the cannula tip to include a diffuser cone angle has been shown for the first time to have potential in ensuring a net positive outflow at the BCA. Cannula insertion distanced from the BCA inlet may also avoid backflow owing to the Venturi effect, but the diffuser tipped cannula design presents a promising solution to mitigate this issue irrespective of in vivo cannula tip orientation.
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Affiliation(s)
- Prahlad G Menon
- Department of Biomedical Engineering, Carnegie Mellon University, 700 Technology Drive, #4319, Pittsburgh, PA, 15219, USA
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Ceballos A, Argueta-Morales IR, Divo E, Osorio R, Caldarone CA, Kassab AJ, DeCampli WM. Computational Analysis of Hybrid Norwood Circulation With Distal Aortic Arch Obstruction and Reverse Blalock-Taussig Shunt. Ann Thorac Surg 2012; 94:1540-50. [DOI: 10.1016/j.athoracsur.2012.06.043] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Revised: 06/11/2012] [Accepted: 06/18/2012] [Indexed: 10/27/2022]
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