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El-Nashar H, Sabry M, Tseng YT, Francis N, Latif N, Parker KH, Moore JE, Yacoub MH. Multiscale structure and function of the aortic valve apparatus. Physiol Rev 2024; 104:1487-1532. [PMID: 37732828 DOI: 10.1152/physrev.00038.2022] [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: 12/07/2022] [Revised: 08/30/2023] [Accepted: 09/01/2023] [Indexed: 09/22/2023] Open
Abstract
Whereas studying the aortic valve in isolation has facilitated the development of life-saving procedures and technologies, the dynamic interplay of the aortic valve and its surrounding structures is vital to preserving their function across the wide range of conditions encountered in an active lifestyle. Our view is that these structures should be viewed as an integrated functional unit, here referred to as the aortic valve apparatus (AVA). The coupling of the aortic valve and root, left ventricular outflow tract, and blood circulation is crucial for AVA's functions: unidirectional flow out of the left ventricle, coronary perfusion, reservoir function, and support of left ventricular function. In this review, we explore the multiscale biological and physical phenomena that underlie the simultaneous fulfillment of these functions. A brief overview of the tools used to investigate the AVA, such as medical imaging modalities, experimental methods, and computational modeling, specifically fluid-structure interaction (FSI) simulations, is included. Some pathologies affecting the AVA are explored, and insights are provided on treatments and interventions that aim to maintain quality of life. The concepts explained in this article support the idea of AVA being an integrated functional unit and help identify unanswered research questions. Incorporating phenomena through the molecular, micro, meso, and whole tissue scales is crucial for understanding the sophisticated normal functions and diseases of the AVA.
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Affiliation(s)
- Hussam El-Nashar
- Aswan Heart Research Centre, Magdi Yacoub Foundation, Cairo, Egypt
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Malak Sabry
- Aswan Heart Research Centre, Magdi Yacoub Foundation, Cairo, Egypt
- Department of Biomedical Engineering, King's College London, London, United Kingdom
| | - Yuan-Tsan Tseng
- Heart Science Centre, Magdi Yacoub Institute, London, United Kingdom
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Nadine Francis
- Aswan Heart Research Centre, Magdi Yacoub Foundation, Cairo, Egypt
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Najma Latif
- Heart Science Centre, Magdi Yacoub Institute, London, United Kingdom
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Kim H Parker
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - James E Moore
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Magdi H Yacoub
- Aswan Heart Research Centre, Magdi Yacoub Foundation, Cairo, Egypt
- Heart Science Centre, Magdi Yacoub Institute, London, United Kingdom
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
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2
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Racz AO, Szabo GT, Papp T, Csippa B, Gyurki D, Kracsko B, Koszegi Z, Kolozsvari R. Potential Clinical Usefulness of Post-Valvular Contrast Densities to Determine the Severity of Aortic Valve Stenosis Using Computed Tomography. J Cardiovasc Dev Dis 2023; 10:412. [PMID: 37887859 PMCID: PMC10607528 DOI: 10.3390/jcdd10100412] [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: 07/30/2023] [Revised: 09/23/2023] [Accepted: 09/26/2023] [Indexed: 10/28/2023] Open
Abstract
BACKGROUND Different methods are established for the changes in aortic valve stenosis with cardiac computed tomography angiography (CCTA), but the effect of the grade of stenosis on contrast densities around the valve has not been investigated. AIMS/METHODS Using the information from flow dynamics in cases of increased velocity through narrowed lumen, the hypothesis was formed that flow changes can alter the contrast densities in stenotic post-valvular regions, and the density changes might correlate with the grade of stenosis. Forty patients with severe aortic stenosis and fifteen with a normal aortic valve were enrolled. With echocardiography, the peak/mean transvalvular gradients, peak transvalvular velocity, and aortic valve opening area were obtained. With CCTA, densities 4-5 mm above the aortic valve; at the junction of the left, right, and noncoronary cusp to the annulus; at the middle level of the left, right, and noncoronary sinuses of Valsalva in the center and the lateral points; at the sinotubular junction; and 4 cm from the sinotubular junction at the midline were measured. First, a comparison of the densities between the normal and stenotic valve was performed, and then possible correlations between echocardiography and CCTA values were investigated in the stenotic group. RESULTS In all CCTA regions, significantly lower-density values were detected among stenotic valve patients compared to the normal aortic valve population. Additionally, in both groups, higher densities were measured in the peri-jet regions than in the lateral ones. Furthermore, a good correlation was found between the aortic valve opening area and the densities in almost all perivalvular areas. With regard to the densities at the junction of the non-coronary leaflet to the fibrotic annulus and at the most lateral point of the right sinus of Valsalva, a high level of correlation was found between all echocardiography and CCTA parameters. Lastly, with receiver operating characteristic curve measurements, area under the curve values were between 0.857 and 0.930. CONCLUSION Certain CCTA density values, especially 4-5mm above the valve opening, can serve as auxiliary information to echocardiography when the severity of aortic valve stenosis is unclear.
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Affiliation(s)
- Agnes Orsolya Racz
- Department of Cardiology and Heart Surgery, University of Debrecen, 4032 Debrecen, Hungary; (A.O.R.); (G.T.S.); (B.K.); (Z.K.)
| | - Gabor Tamas Szabo
- Department of Cardiology and Heart Surgery, University of Debrecen, 4032 Debrecen, Hungary; (A.O.R.); (G.T.S.); (B.K.); (Z.K.)
| | - Tamas Papp
- Department of Radiology, University of Debrecen, 4032 Debrecen, Hungary;
| | - Benjamin Csippa
- Department of Hydrodynamic Systems, University of Technology and Economics, 1111 Budapest, Hungary; (B.C.); (D.G.)
| | - Daniel Gyurki
- Department of Hydrodynamic Systems, University of Technology and Economics, 1111 Budapest, Hungary; (B.C.); (D.G.)
| | - Bertalan Kracsko
- Department of Cardiology and Heart Surgery, University of Debrecen, 4032 Debrecen, Hungary; (A.O.R.); (G.T.S.); (B.K.); (Z.K.)
| | - Zsolt Koszegi
- Department of Cardiology and Heart Surgery, University of Debrecen, 4032 Debrecen, Hungary; (A.O.R.); (G.T.S.); (B.K.); (Z.K.)
- 3rd Department of Internal Medicine, Szabolcs-Szatmar-Bereg County Hospital, 4400 Nyíregyháza, Hungary
| | - Rudolf Kolozsvari
- Department of Cardiology and Heart Surgery, University of Debrecen, 4032 Debrecen, Hungary; (A.O.R.); (G.T.S.); (B.K.); (Z.K.)
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3
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Cantinotti M, Marchese P, Scalese M, Giordano R, Franchi E, Assanta N, Koestenberger M, Barnes BT, Celi S, Jani V, Voges I, Kutty S. Characterization of Aortic Flow Patterns by High-Frame-Rate Blood Speckle Tracking Echocardiography in Children. J Am Heart Assoc 2023; 12:e026335. [PMID: 37066781 PMCID: PMC10227241 DOI: 10.1161/jaha.122.026335] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 12/26/2022] [Indexed: 04/18/2023]
Abstract
Background Blood speckle tracking echocardiography allows for direct quantification of interventricular and aortic flow profiles, principally in children. Here, we sought to demonstrate the feasibility and reproducibility of blood speckle tracking echocardiography in the aortas of healthy children. Methods and Results One hundred healthy White children evaluated for the screening of congenital heart disease were prospectively enrolled. Echocardiographic examinations were performed using a Vivid E 95 ultrasound system, with blood speckle tracking from a focused and zoomed view of the aortic root and the ascending aorta. Vortex position, height (mm), width (mm), sphericity index, and area (cm2) were measured and indexed by body surface area. Median (interquartile range) age was 8.2 (5.6-11.0) years, median (interquartile range) weight was 28 (19-35) kg, and median (interquartile range) body surface area was 1.01 (0.79-1.16) m2. Vortices were visualized in only a single phase of the cardiac cycle in 25 subjects-14 (56.0%) were evident in early diastole and 11 (44.0%) in late systole. Vortices visualized in diastole had a mean area of 0.27±0.1 cm2/m2, while those in systole had a mean area of 0.34±0.12 cm2/m2. In a subset of 20 patients, inter- and intraobserver coefficient of variation and intraclass correlation coefficients were determined and showed good reproducibility. Conclusions We demonstrate feasibility and reproducibility of blood speckle tracking and identified vortical flow patterns in the aortic root and ascending aorta in healthy children. These data may serve as a baseline for evaluating aortic flow patterns in children with congenital and acquired heart disease.
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Affiliation(s)
- Massimiliano Cantinotti
- Fondazione G. Monasterio CNR‐Regione ToscanaMassa, PisaItaly
- Adult Institute of Clinical PhysiologyPisaItaly
| | - Pietro Marchese
- Fondazione G. Monasterio CNR‐Regione ToscanaMassa, PisaItaly
- Scuola Superiore Sant’AnnaPisaItaly
| | | | - Raffaele Giordano
- Adult and Pediatric Cardiac Surgery, Department Advanced Biomedical SciencesUniversity of Naples “Federico II”NapoliItaly
| | - Eliana Franchi
- Fondazione G. Monasterio CNR‐Regione ToscanaMassa, PisaItaly
| | - Nadia Assanta
- Fondazione G. Monasterio CNR‐Regione ToscanaMassa, PisaItaly
| | - Martin Koestenberger
- Division of Pediatric Cardiology, Department of PediatricsMedical University GrazGrazAustria
| | - Benjamin T. Barnes
- Department of PediatricsTaussig Heart Center, Johns Hopkins HospitalBaltimoreMDUSA
| | - Simona Celi
- Fondazione G. Monasterio CNR‐Regione ToscanaMassa, PisaItaly
| | - Vivek Jani
- Department of PediatricsTaussig Heart Center, Johns Hopkins HospitalBaltimoreMDUSA
| | - Inga Voges
- Department for Congenital Cardiology and Pediatric CardiologyUniversity Hospital Schleswig‐HolsteinCampus KielGermany
| | - Shelby Kutty
- Department of PediatricsTaussig Heart Center, Johns Hopkins HospitalBaltimoreMDUSA
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Roos PR, Rijnberg FM, Westenberg JJM, Lamb HJ. Particle Tracing Based on
4D
Flow Magnetic Resonance Imaging: A Systematic Review into Methods, Applications, and Current Developments. J Magn Reson Imaging 2022; 57:1320-1339. [PMID: 36484213 DOI: 10.1002/jmri.28540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 11/15/2022] [Accepted: 11/15/2022] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Particle tracing based on 4D Flow MRI has been applied as a quantitative and qualitative postprocessing technique to study temporally evolving blood flow patterns. PURPOSE To systematically review the various methods to perform 4D Flow MRI-based particle tracing, as well as the clinical value, clinical applications, and current developments of the technique. STUDY TYPE The study type is systematic review. SUBJECTS Patients with cardiovascular disease (such as Marfan, Fontan, Tetralogy of Fallot), healthy controls, and cardiovascular phantoms that received 4D Flow MRI with particle tracing. FIELD STRENGTH/SEQUENCE Three-dimensional three-directional cine phase-contrast MRI, at 1.5 T and 3 T. ASSESSMENT Two systematic searches were performed on the PubMed database using Boolean operators and the relevant key terms covering 4D Flow MRI and particle tracing. One systematic search was focused on particle tracing methods, whereas the other on applications. Additional articles from other sources were sought out and included after a similar inspection. Particle tracing methods, clinical applications, clinical value, and current developments were extracted. STATISTICAL TESTS The main results of the included studies are summarized, without additional statistical analysis. RESULTS Of 127 unique articles retrieved from the initial search, 56 were included (28 for methods and 54 for applications). Most articles that described particle tracing methods used an adaptive timestep, a fourth order Runge-Kutta integration method, and linear interpolation in the time dimension. Particle tracing was applied in heart chambers, aorta, venae cavae, Fontan circulation, pulmonary arteries, abdominal vasculature, peripheral arteries, carotid arteries, and cerebral vasculature. Applications were grouped as intravascular, intracardiac, flow stasis, and research. DATA CONCLUSIONS Particle tracing based on 4D Flow MRI gives unique insight into blood flow in several cardiovascular diseases, but the quality depends heavily on the MRI data quality. Further studies are required to evaluate the clinical value of the technique for different cardiovascular diseases. EVIDENCE LEVEL 5. TECHNICAL EFFICACY Stage 1.
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Affiliation(s)
- Paul R. Roos
- Department of Radiology Leiden University Medical Center Leiden The Netherlands
| | - Friso M. Rijnberg
- Department of Cardiothoracic Surgery Leiden University Medical Center Leiden The Netherlands
| | | | - Hildo J. Lamb
- Department of Radiology Leiden University Medical Center Leiden The Netherlands
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5
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Abstract
This special issue of Magnetic Resonance in Medical Sciences features the most recent reviews on 4D Flow MRI. These reviews deal with the current status of the emerging technique of 4D Flow MRI facilitated in various areas that are difficult to obtain with conventional flowmetry. MR signals inherently contain flow velocity information. In previous decades, in vivo blood flow measurement was traditionally performed by 2D methods, such as Doppler ultrasonography and 2D phase-contrast MRI, which have long been regarded as mature techniques in hemodynamic flowmetry. Although 2D velocimetries have many advantages over 4D Flow MRI in terms of cost and accessibility, and provide excellent temporal and in-plane spatial resolutions, they also have some disadvantages. The emerging technology of 4D Flow MRI can overcome the shortcomings of conventional 2D imaging. In recent years, hemodynamic analysis has witnessed significant progress that is primarily attributable to advances in 4D Flow MRI.
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Affiliation(s)
- Yasuo Takehara
- Department of Fundamental Development for Low Invasive Diagnostic Imaging, Nagoya University Graduate School of Medicine
| | - Tetsuro Sekine
- Department of Radiology, Nippon Medical School Musashi Kosugi Hospital
| | - Takayuki Obata
- Applied MRI Research, Department of Molecular Imaging and Theranostics, National Institutes for Quantum Science and Technology
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Cvitkovic T, Bobylev D, Horke A, Avsar M, Beerbaum P, Martens A, Böthig D, Petenà E, Gutberlet M, Beyer FH, Wacker F, Cebotari S, Haverich A, Vogel-Claussen J, Sarikouch S, Czerner C. OUP accepted manuscript. Eur J Cardiothorac Surg 2022; 61:1307-1315. [PMID: 35079774 PMCID: PMC9154340 DOI: 10.1093/ejcts/ezac016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 11/29/2021] [Accepted: 01/10/2022] [Indexed: 11/13/2022] Open
Affiliation(s)
- Tomislav Cvitkovic
- Department for Cardiothoracic, Transplant, and Vascular Surgery, Hannover Medical School, Hannover, Germany
- Corresponding author. Department for Cardiothoracic, Transplant, and Vascular Surgery, Hannover Medical School, Carl-Neuberg-Str. 1, Hannover 30625, Germany. Tel: +49-511-532-9829; e-mail: (T. Cvitkovic)
| | - Dmitry Bobylev
- Department for Cardiothoracic, Transplant, and Vascular Surgery, Hannover Medical School, Hannover, Germany
| | - Alexander Horke
- Department for Cardiothoracic, Transplant, and Vascular Surgery, Hannover Medical School, Hannover, Germany
| | - Murat Avsar
- Department for Cardiothoracic, Transplant, and Vascular Surgery, Hannover Medical School, Hannover, Germany
| | - Philipp Beerbaum
- Department for Pediatric Cardiology and Intensive Care, Hannover Medical School, Hannover, Germany
| | - Andreas Martens
- Department for Cardiothoracic, Transplant, and Vascular Surgery, Hannover Medical School, Hannover, Germany
| | - Dietmar Böthig
- Department for Cardiothoracic, Transplant, and Vascular Surgery, Hannover Medical School, Hannover, Germany
| | - Elena Petenà
- Department for Cardiothoracic, Transplant, and Vascular Surgery, Hannover Medical School, Hannover, Germany
| | - Marcel Gutberlet
- Institute for Diagnostic and Interventional Radiology, Hannover Medical School, Hannover, Germany
| | - Frerk Hinnerk Beyer
- Institute for Diagnostic and Interventional Radiology, Hannover Medical School, Hannover, Germany
| | - Frank Wacker
- Institute for Diagnostic and Interventional Radiology, Hannover Medical School, Hannover, Germany
| | - Serghei Cebotari
- Department for Cardiothoracic, Transplant, and Vascular Surgery, Hannover Medical School, Hannover, Germany
| | - Axel Haverich
- Department for Cardiothoracic, Transplant, and Vascular Surgery, Hannover Medical School, Hannover, Germany
| | - Jens Vogel-Claussen
- Institute for Diagnostic and Interventional Radiology, Hannover Medical School, Hannover, Germany
| | - Samir Sarikouch
- Department for Cardiothoracic, Transplant, and Vascular Surgery, Hannover Medical School, Hannover, Germany
| | - Christoph Czerner
- Institute for Diagnostic and Interventional Radiology, Hannover Medical School, Hannover, Germany
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7
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Sieren MM, Balks MF, Schlueter JK, Wegner F, Huellebrand M, Scharfschwerdt M, Barkhausen J, Frydrychowicz A, Gabbert DD, Oechtering TH. Comprehensive analysis of haemodynamics in patients with physiologically curved prostheses of the ascending aorta. Eur J Cardiothorac Surg 2021; 62:6354573. [PMID: 34409435 DOI: 10.1093/ejcts/ezab352] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Revised: 06/22/2021] [Accepted: 06/25/2021] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVES This is a comprehensive analysis of haemodynamics after valve-sparing aortic root replacement (VSARR) with anatomically curved prosthesis (CP) compared to straight prosthesis (SP) and age-matched volunteers (VOL) using 4D flow MRI (time-resolved three-dimensional magnetic resonance phase-contrast imaging). METHODS Nine patients with 90° CP, nine patients with SP, and twelve VOL were examined with 4D flow MRI. Analyses included various characteristic anatomical, qualitative and quantitative haemodynamic parameters. RESULTS Grading of secondary flow patterns was lower in CP patients than in SP patients (P = 0.09) and more comparable to VOL, albeit not reaching statistical significance. However, it was easy to differentiate between VSARR patients and healthy volunteers: Patients more often had angular aortic arches (CP: 89%, SP: 100%; VOL: 17%; P ≤ 0.002), increased average curvature (CP: 0.17/cm [0.15, 0.18]; SP: 0.15/cm [0.14, 0.16]; VOL: 0.14/cm [0.13, 0.16]; P ≤ 0.007; values given as median [interquartile range]), and more secondary flow patterns (CP: 3 [2, 4] SP: 3 [2, 3] VOL: 2 [1, 2]; P < 0.01). Maximum circulation (CP: 142.7 cm2/s [116.1, 187.3]; SP: 101.8 cm2/s [77.7, 132.5]; VOL: 42.8cm2/s [39.3, 65.6]; P ≤ 0.002), maximum helicity density (CP: 9.6 m/s2 [9.3, 23.9]; SP: 9.7 m/s2 [8.6, 12.5]; VOL 4.9 m/s2 [4.2, 7.7]; P ≤ 0.007), and wall shear stress gradient (e.g., proximal ascending aorta CP: 0.97 N/m2 [0.54, 1.07]; SP: 1.08 N/m2 [0.74, 1.24]; VOL: 0.41 N/m2 [0.32, 0.60]; P ≤ 0.01) were increased in patients. One CP patient had a round aortic arch with physiological haemodynamic parameters. CONCLUSIONS The restoration of physiological aortic configuration and haemodynamics was not fully achieved with the curved prostheses in our study cohort. However, there was a tendency towards improved haemodynamic conditions in the patients with curved prostheses overall but without statistical significance. A single patient with a CP and near-physiological configuration of the thoracic aorta underlines the importance of optimizing postoperative geometric conditions for allowing for physiological haemodynamics and cardiovascular energetics after VSARR.
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Affiliation(s)
- Malte Maria Sieren
- Department of Radiology and Nuclear Medicine, Universität zu Lübeck, Lübeck, Germany
| | | | | | - Franz Wegner
- Department of Radiology and Nuclear Medicine, Universität zu Lübeck, Lübeck, Germany
| | | | | | - Jörg Barkhausen
- Department of Radiology and Nuclear Medicine, Universität zu Lübeck, Lübeck, Germany
| | - Alex Frydrychowicz
- Department of Radiology and Nuclear Medicine, Universität zu Lübeck, Lübeck, Germany
| | - Dominik Daniel Gabbert
- Department of Congenital Heart Disease and Pediatric Cardiology, University Hospital of Schleswig-Holstein, Campus Kiel, Germany
| | - Thekla Helene Oechtering
- Department of Radiology and Nuclear Medicine, Universität zu Lübeck, Lübeck, Germany.,Department of Radiology, University of Wisconsin-Madison, Madison, WI, USA
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8
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Superimposed Tissue Formation in Human Aortic Valve Disease: Differences between Regurgitant and Stenotic Valves. J Cardiovasc Dev Dis 2021; 8:jcdd8070079. [PMID: 34357322 PMCID: PMC8306480 DOI: 10.3390/jcdd8070079] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2021] [Revised: 06/29/2021] [Accepted: 07/05/2021] [Indexed: 12/12/2022] Open
Abstract
The formation of superimposed tissue (SIT), a layer on top of the original valve leaflet, has been described in patients with mitral regurgitation as a major contributor to valve thickening and possibly as a result of increased mechanical stresses. However, little is known whether SIT formation also occurs in aortic valve disease. We therefore performed histological analyses to assess SIT formation in aortic valve leaflets (n = 31) from patients with aortic stenosis (n = 17) or aortic regurgitation due to aortic dilatation (n = 14). SIT was observed in both stenotic and regurgitant aortic valves, both on the ventricular and aortic sides, but with significant differences in distribution and composition. Regurgitant aortic valves showed more SIT formation in the free edge, leading to a thicker leaflet at that level, while stenotic aortic valves showed relatively more SIT formation on the aortic side of the body part of the leaflet. SIT appeared to be a highly active area, as determined by large populations of myofibroblasts, with varied extracellular matrix composition (higher collagen content in stenotic valves). Further, the identification of the SIT revealed the presence of foldings of the free edge in the diseased aortic valves. Insights into SIT regulation may further help in understanding the pathophysiology of aortic valve disease and potentially lead to the development of new therapeutic treatments.
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9
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Paulsen MJ, Imbrie-Moore AM, Baiocchi M, Wang H, Hironaka CE, Lucian HJ, Farry JM, Thakore AD, Zhu Y, Ma M, MacArthur JW, Woo YJ. Comprehensive Ex Vivo Comparison of 5 Clinically Used Conduit Configurations for Valve-Sparing Aortic Root Replacement Using a 3-Dimensional-Printed Heart Simulator. Circulation 2020; 142:1361-1373. [PMID: 33017215 PMCID: PMC7531510 DOI: 10.1161/circulationaha.120.046612] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Supplemental Digital Content is available in the text. Background: Many graft configurations are clinically used for valve-sparing aortic root replacement, some specifically focused on recapitulating neosinus geometry. However, the specific impact of such neosinuses on valvular and root biomechanics and the potential influence on long-term durability are unknown. Methods: Using a custom 3-dimenstional–printed heart simulator with porcine aortic roots (n=5), the anticommissural plication, Stanford modification, straight graft (SG), Uni-Graft, and Valsalva graft configurations were tested in series using an incomplete counterbalanced measures design, with the native root as a control, to mitigate ordering effects. Hemodynamic and videometric data were analyzed using linear models with conduit as the fixed effect of interest and valve as a fixed nuisance effect with post hoc pairwise testing using Tukey’s correction. Results: Hemodynamics were clinically similar between grafts and control aortic roots. Regurgitant fraction varied between grafts, with SG and Uni-Graft groups having the lowest regurgitant fractions and anticommissural plication having the highest. Root distensibility was significantly lower in SG versus both control roots and all other grafts aside from the Stanford modification (P≤0.01 for each). All grafts except SG had significantly higher cusp opening velocities versus native roots (P<0.01 for each). Relative cusp opening forces were similar between SG, Uni-Graft, and control groups, whereas anticommissural plication, Stanford modification, and Valsalva grafts had significantly higher opening forces versus controls (P<0.01). Cusp closing velocities were similar between native roots and the SG group, and were significantly lower than observed in the other conduits (P≤0.01 for each). Only SG and Uni-Graft groups experienced relative cusp closing forces approaching that of the native root, whereas relative forces were >5-fold higher in the anticommissural plication, Stanford modification, and Valsalva graft groups. Conclusions: In this ex vivo modeling system, clinically used valve-sparing aortic root replacement conduit configurations have comparable hemodynamics but differ in biomechanical performance, with the straight graft most closely recapitulating native aortic root biomechanics.
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Affiliation(s)
- Michael J Paulsen
- Department of Cardiothoracic Surgery (M.J.P., A.M.I.-M., M.B., H.W., C.E.H., H.J.L., J.M.F., A.D.T., Y.Z., M.M., J.W.M., Y.J.W.), Stanford University, CA
| | - Annabel M Imbrie-Moore
- Department of Cardiothoracic Surgery (M.J.P., A.M.I.-M., M.B., H.W., C.E.H., H.J.L., J.M.F., A.D.T., Y.Z., M.M., J.W.M., Y.J.W.), Stanford University, CA.,Department of Mechanical Engineering (A.M.I.M.), Stanford University, CA
| | - Michael Baiocchi
- Department of Cardiothoracic Surgery (M.J.P., A.M.I.-M., M.B., H.W., C.E.H., H.J.L., J.M.F., A.D.T., Y.Z., M.M., J.W.M., Y.J.W.), Stanford University, CA.,Department of Health Research and Policy (M.B.), Stanford University, CA
| | - Hanjay Wang
- Department of Cardiothoracic Surgery (M.J.P., A.M.I.-M., M.B., H.W., C.E.H., H.J.L., J.M.F., A.D.T., Y.Z., M.M., J.W.M., Y.J.W.), Stanford University, CA
| | - Camille E Hironaka
- Department of Cardiothoracic Surgery (M.J.P., A.M.I.-M., M.B., H.W., C.E.H., H.J.L., J.M.F., A.D.T., Y.Z., M.M., J.W.M., Y.J.W.), Stanford University, CA
| | - Haley J Lucian
- Department of Cardiothoracic Surgery (M.J.P., A.M.I.-M., M.B., H.W., C.E.H., H.J.L., J.M.F., A.D.T., Y.Z., M.M., J.W.M., Y.J.W.), Stanford University, CA
| | - Justin M Farry
- Department of Cardiothoracic Surgery (M.J.P., A.M.I.-M., M.B., H.W., C.E.H., H.J.L., J.M.F., A.D.T., Y.Z., M.M., J.W.M., Y.J.W.), Stanford University, CA
| | - Akshara D Thakore
- Department of Cardiothoracic Surgery (M.J.P., A.M.I.-M., M.B., H.W., C.E.H., H.J.L., J.M.F., A.D.T., Y.Z., M.M., J.W.M., Y.J.W.), Stanford University, CA
| | - Yuanjia Zhu
- Department of Cardiothoracic Surgery (M.J.P., A.M.I.-M., M.B., H.W., C.E.H., H.J.L., J.M.F., A.D.T., Y.Z., M.M., J.W.M., Y.J.W.), Stanford University, CA
| | - Michael Ma
- Department of Cardiothoracic Surgery (M.J.P., A.M.I.-M., M.B., H.W., C.E.H., H.J.L., J.M.F., A.D.T., Y.Z., M.M., J.W.M., Y.J.W.), Stanford University, CA
| | - John W MacArthur
- Department of Cardiothoracic Surgery (M.J.P., A.M.I.-M., M.B., H.W., C.E.H., H.J.L., J.M.F., A.D.T., Y.Z., M.M., J.W.M., Y.J.W.), Stanford University, CA
| | - Y Joseph Woo
- Department of Cardiothoracic Surgery (M.J.P., A.M.I.-M., M.B., H.W., C.E.H., H.J.L., J.M.F., A.D.T., Y.Z., M.M., J.W.M., Y.J.W.), Stanford University, CA.,Department of Bioengineering (Y.J.W.), Stanford University, CA
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10
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Catapano F, Pambianchi G, Cundari G, Rebelo J, Cilia F, Carbone I, Catalano C, Francone M, Galea N. 4D flow imaging of the thoracic aorta: is there an added clinical value? Cardiovasc Diagn Ther 2020; 10:1068-1089. [PMID: 32968661 DOI: 10.21037/cdt-20-452] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Four-dimensional (4D) flow MRI has emerged as a powerful non-invasive technique in cardiovascular imaging, enabling to analyse in vivo complex flow dynamics models by quantifying flow parameters and derived features. Deep knowledge of aortic flow dynamics is fundamental to better understand how abnormal flow patterns may promote or worsen vascular diseases. In the perspective of an increasingly personalized and preventive medicine, growing interest is focused on identifying those quantitative functional features which are early predictive markers of pathological evolution. The thoracic aorta and its spectrum of diseases, as the first area of application and development of 4D flow MRI and supported by an extensive experimental validation, represents the ideal model to introduce this technique into daily clinical practice. The purpose of this review is to describe the impact of 4D flow MRI in the assessment of the thoracic aorta and its most common affecting diseases, providing an overview of the actual clinical applications and describing the potential role of derived advanced hemodynamic measures in tailoring follow-up and treatment.
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Affiliation(s)
- Federica Catapano
- Department of Radiological, Oncological and Pathological Sciences, Sapienza University of Rome, Rome, Italy
| | - Giacomo Pambianchi
- Department of Radiological, Oncological and Pathological Sciences, Sapienza University of Rome, Rome, Italy
| | - Giulia Cundari
- Department of Radiological, Oncological and Pathological Sciences, Sapienza University of Rome, Rome, Italy
| | - João Rebelo
- Department of Radiology, Centro Hospitalar São João, Alameda Prof. Hernâni Monteiro, Porto, Portugal
| | - Francesco Cilia
- Department of Radiological, Oncological and Pathological Sciences, Sapienza University of Rome, Rome, Italy
| | - Iacopo Carbone
- Department of Radiological, Oncological and Pathological Sciences, Sapienza University of Rome, Rome, Italy
| | - Carlo Catalano
- Department of Radiological, Oncological and Pathological Sciences, Sapienza University of Rome, Rome, Italy
| | - Marco Francone
- Department of Radiological, Oncological and Pathological Sciences, Sapienza University of Rome, Rome, Italy
| | - Nicola Galea
- Department of Radiological, Oncological and Pathological Sciences, Sapienza University of Rome, Rome, Italy.,Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy
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11
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Sieren MM, Schultz V, Fujita B, Wegner F, Huellebrand M, Scharfschwerdt M, Sievers HH, Barkhausen J, Frydrychowicz A, Oechtering TH. 4D flow CMR analysis comparing patients with anatomically shaped aortic sinus prostheses, tube prostheses and healthy subjects introducing the wall shear stress gradient: a case control study. J Cardiovasc Magn Reson 2020; 22:59. [PMID: 32772927 PMCID: PMC7416416 DOI: 10.1186/s12968-020-00653-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 07/08/2020] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Anatomically pre-shaped sinus prostheses (SP) were developed to mimic the aortic sinus with the goal to preserve near physiological hemodynamic conditions after valve-sparing aortic root replacement. Although SP have shown more physiological flow patterns, a comparison to straight tube prosthesis and the analysis of derived quantitative parameters is lacking. Hence, this study sought to analyze differences in aortic wall shear stress (WSS) between anatomically pre-shaped SP, conventional straight tube prostheses (TP), and age-matched healthy subjects) using time-resolved 3-dimensional flow cardiovascular magnetic resonance (4D Flow CMR). Moreover, the WSS gradient was introduced and analyzed regarding its sensitivity to detect changes in hemodynamics and its dependency on the expression of secondary flow patterns. METHODS Twelve patients with SP (12 male, 62 ± 9yr), eight patients with TP (6 male, 59 ± 9yr), and twelve healthy subjects (2 male, 55 ± 6yr) were examined at 3 T with a 4D Flow CMR sequence in this case control study. Six analysis planes were placed in the thoracic aorta at reproducible landmarks. The following WSS parameters were recorded: WSSavg (spatially averaged over the contour at peak systole), max. WSSseg (maximum segmental WSS), min. WSSseg (minimum segmental WSS) and the WSS Gradient, calculated as max. WSSseg - min. WSSseg. Kruskal-Wallis- and Mann-Whitney-U-Test were used for statistical comparison of groups. Occurrence and expression of secondary flow patterns were evaluated and correlated to WSS values using Spearman's correlation coefficient. RESULTS In the planes bordering the prosthesis all WSS values were significantly lower in the SP compared to the TP, approaching the physiological optimum of the healthy subjects. The WSS gradient showed significantly different values in the four proximally localized contours when comparing both prostheses with healthy subjects. Strong correlations between an elevated WSS gradient and secondary flow patterns were found in the ascending aorta and the aortic arch. CONCLUSION Overall, the SP has a positive impact on WSS, most pronounced at the site and adjacent to the prosthesis. The WSS gradient differed most obviously and the correlation of the WSS gradient with the occurrence of secondary flow patterns provides further evidence for linking disturbed flow, which was markedly increased in patients compared to healthy sub jects, to degenerative remodeling of the vascular wall.
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Affiliation(s)
- Malte Maria Sieren
- Department for Radiology and Nuclear Medicine, Ratzeburger Allee 160, 23562, Lübeck, Germany.
| | - Victoria Schultz
- Department for Radiology and Nuclear Medicine, Ratzeburger Allee 160, 23562, Lübeck, Germany
| | - Buntaro Fujita
- Department for Cardiac and Cardiothoracic Vascular Surgery, University Hospital Schleswig-Holstein, Lübeck, Germany
| | - Franz Wegner
- Department for Radiology and Nuclear Medicine, Ratzeburger Allee 160, 23562, Lübeck, Germany
| | | | - Michael Scharfschwerdt
- Department for Cardiac and Cardiothoracic Vascular Surgery, University Hospital Schleswig-Holstein, Lübeck, Germany
| | - Hans-Hinrich Sievers
- Department for Cardiac and Cardiothoracic Vascular Surgery, University Hospital Schleswig-Holstein, Lübeck, Germany
| | - Joerg Barkhausen
- Department for Radiology and Nuclear Medicine, Ratzeburger Allee 160, 23562, Lübeck, Germany
| | - Alex Frydrychowicz
- Department for Radiology and Nuclear Medicine, Ratzeburger Allee 160, 23562, Lübeck, Germany
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12
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Zhuang Z, Liu G, Ding W, Raj ANJ, Qiu S, Guo J, Yuan Y. Cardiac VFM visualization and analysis based on YOLO deep learning model and modified 2D continuity equation. Comput Med Imaging Graph 2020; 82:101732. [DOI: 10.1016/j.compmedimag.2020.101732] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Revised: 03/23/2020] [Accepted: 04/13/2020] [Indexed: 11/16/2022]
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13
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Morichi H, Itatani K, Yamazaki S, Numata S, Nakaji K, Tamaki N, Yaku H. Influences of mitral annuloplasty on left ventricular flow dynamics assessed with 3-dimensional cine phase-contrast flow magnetic resonance imaging. J Thorac Cardiovasc Surg 2020; 163:947-959. [PMID: 32690416 DOI: 10.1016/j.jtcvs.2020.04.127] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 03/24/2020] [Accepted: 04/09/2020] [Indexed: 11/30/2022]
Abstract
OBJECTIVES We assessed the influence of annuloplasty procedures in mitral repair on left ventricular (LV) vortex flow patterns and aortic outflow patterns, and flow energy loss (EL). METHODS Twenty healthy volunteers and 14 patients who had undergone mitral valve repair were examined using 3-dimensional cine phase-contrast magnetic resonance imaging. A band group included 7 patients with semi-rigid and 2 with flexible partial bands. The ring group included 5 patients with semi-rigid complete rings. LV vortex flow patterns, aortic outflow patterns, EL, and aortic annulus changes during one cardiac cycle were evaluated. RESULTS Mitral repair induced different vortex flow patterns compared with that of healthy volunteers. The vortex beneath the anterior mitral leaflet with semi-rigid devices was double-stranded in early diastole, and it was single-stranded with flexible bands with a large shift toward the apex during diastole. LVEL in patients who underwent mitral repair (0.84 ± 0.42 mW) was greater than that in healthy volunteers (0.47 ± 0.10 mW). Complete rings disturbed aortic outflow patterns, with EL distribution changes. Smaller devices relative to patient body size disturbed LV flow patterns and caused high EL. No significant relationship was found between indexed ring orifice area and transmitral mean pressure gradient (r = -0.25, P = .414), but a negative relationship exists between indexed ring orifice area and LVEL (r = -0.84, P < .001). CONCLUSIONS Mitral repair, especially with relatively small annuloplasty rings, induced abnormal LV flow patterns and EL elevation, which have the potential to be a novel hemodynamic evaluation method after mitral repair.
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Affiliation(s)
- Hiroko Morichi
- Department of Cardiovascular Surgery, Cardiovascular Imaging Research Laboratory, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Keiichi Itatani
- Department of Cardiovascular Surgery, Cardiovascular Imaging Research Laboratory, Kyoto Prefectural University of Medicine, Kyoto, Japan.
| | - Sachiko Yamazaki
- Department of Cardiovascular Surgery, Cardiovascular Imaging Research Laboratory, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Satoshi Numata
- Department of Cardiovascular Surgery, Cardiovascular Imaging Research Laboratory, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Kosuke Nakaji
- Department of Radiology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Nagara Tamaki
- Department of Radiology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Hitoshi Yaku
- Department of Cardiovascular Surgery, Cardiovascular Imaging Research Laboratory, Kyoto Prefectural University of Medicine, Kyoto, Japan
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14
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Jarral OA, Tan MKH, Salmasi MY, Pirola S, Pepper JR, O'Regan DP, Xu XY, Athanasiou T. Phase-contrast magnetic resonance imaging and computational fluid dynamics assessment of thoracic aorta blood flow: a literature review. Eur J Cardiothorac Surg 2020; 57:438-446. [PMID: 31638698 DOI: 10.1093/ejcts/ezz280] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2019] [Revised: 09/06/2019] [Accepted: 09/17/2019] [Indexed: 11/14/2022] Open
Abstract
The death rate from thoracic aortic disease is on the rise and represents a growing global health concern as patients are often asymptomatic before acute events, which have devastating effects on health-related quality of life. Biomechanical factors have been found to play a major role in the development of both acquired and congenital aortic diseases. However, much is still unknown and translational benefits of this knowledge are yet to be seen. Phase-contrast cardiovascular magnetic resonance imaging of thoracic aortic blood flow has emerged as an exceptionally powerful non-invasive tool enabling visualization of complex flow patterns, and calculation of variables such as wall shear stress. This has led to multiple new findings in the areas of phenotype-dependent bicuspid valve flow patterns, thoracic aortic aneurysm formation and aortic prosthesis performance assessment. Phase-contrast cardiovascular magnetic resonance imaging has also been used in conjunction with computational fluid modelling techniques to produce even more sophisticated analyses, by allowing the calculation of haemodynamic variables with exceptional temporal and spatial resolution. Translationally, these technologies may potentially play a major role in the emergence of precision medicine and patient-specific treatments in patients with aortic disease. This clinically focused review will provide a systematic overview of key insights from published studies to date.
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Affiliation(s)
- Omar A Jarral
- Department of Surgery and Cancer, Imperial College London, London, UK
| | - Matthew K H Tan
- Department of Surgery and Cancer, Imperial College London, London, UK
| | | | - Selene Pirola
- Department of Chemical Engineering, Imperial College London, London, UK
| | - John R Pepper
- National Heart and Lung Institute, Imperial College London, London, UK
| | - Declan P O'Regan
- MRC London Institute of Medical Sciences, Imperial College London, London, UK
| | - Xiao Y Xu
- Department of Chemical Engineering, Imperial College London, London, UK
| | - Thanos Athanasiou
- Department of Surgery and Cancer, Imperial College London, London, UK
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15
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Oechtering TH, Sieren MM, Hunold P, Hennemuth A, Huellebrand M, Scharfschwerdt M, Richardt D, Sievers HH, Barkhausen J, Frydrychowicz A. Time-resolved 3-dimensional magnetic resonance phase contrast imaging (4D Flow MRI) reveals altered blood flow patterns in the ascending aorta of patients with valve-sparing aortic root replacement. J Thorac Cardiovasc Surg 2020; 159:798-810.e1. [DOI: 10.1016/j.jtcvs.2019.02.127] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Revised: 02/12/2019] [Accepted: 02/25/2019] [Indexed: 10/27/2022]
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16
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Sadri V, Madukauwa-David ID, Yoganathan AP. In vitro evaluation of a new aortic valved conduit. J Thorac Cardiovasc Surg 2019; 161:581-590.e6. [PMID: 31879167 DOI: 10.1016/j.jtcvs.2019.09.181] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 09/16/2019] [Accepted: 09/19/2019] [Indexed: 11/24/2022]
Abstract
BACKGROUND This study examined whether the presence of a sinus of Valsalva equivalent in the KONECT RESILIA aortic valved conduit (Edwards Lifesciences, Irvine, Calif) improves valve hemodynamics, kinematics, and performance. METHODS A 28-mm KONECT RESILIA aortic valved conduit was used to create an in vitro flow test model, and the same aortic valved conduit model without a sinus section was used as a control. Particle image velocimetry and hydrodynamic characterization experiments were conducted in the vicinity of the valves in a validated left-heart simulator at 3 cardiac output levels. In addition, leaflet kinematics of the valves were determined through en face high-speed imaging. RESULTS The KONECT RESILIA aortic valved conduit model exhibited lower mean and peak transvalvular pressure gradients than the control model at all 3 cardiac outputs. In addition, its leaflets opened more fully than did those of the valved conduit without the sinuses, yielding greater effective and geometric orifice areas. It was found that the presence of the sinuses not only facilitated the development of larger and more stable vortices at the initial stages of the cardiac cycle but also helped to maintain these vortices during the late stages of the cardiac cycle, leading to smoother valve closure. CONCLUSIONS The KONECT RESILIA aortic valved conduit reproduces the bulged section of the aortic root corresponding to the sinuses of Valsalva. With this Valsalva-type conduit, larger orifice areas were observed, improving valve hemodynamics that may enhance performance.
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Affiliation(s)
- Vahid Sadri
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Ga
| | | | - Ajit P Yoganathan
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Ga.
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17
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Diagnostic and prognostic significance of cardiovascular vortex formation. J Cardiol 2019; 74:403-411. [DOI: 10.1016/j.jjcc.2019.05.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2019] [Accepted: 05/07/2019] [Indexed: 12/16/2022]
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18
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19
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Modeling conduit choice for valve-sparing aortic root replacement on biomechanics with a 3-dimensional–printed heart simulator. J Thorac Cardiovasc Surg 2019; 158:392-403. [DOI: 10.1016/j.jtcvs.2018.10.145] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 10/07/2018] [Accepted: 10/19/2018] [Indexed: 12/24/2022]
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20
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Comprehensive In Vitro Study of the Flow Past Two Transcatheter Aortic Valves: Comparison with a Severe Stenotic Case. Ann Biomed Eng 2019; 47:2241-2257. [DOI: 10.1007/s10439-019-02289-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 05/10/2019] [Indexed: 11/25/2022]
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21
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Lansac E, Lim HS, Shomura Y, Lim KH, Rice NT, Di Centa I, Youssefi P, Goetz W, Duran CMG. Aortic valve opening and closure: the clover dynamics. Ann Cardiothorac Surg 2019; 8:351-361. [PMID: 31240179 DOI: 10.21037/acs.2019.05.03] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Background Systolic aortic root expansion is reported to facilitate valve opening, but the precise dynamics remain unknown. A sonometric study with a high data sampling rate (200 to 800 Hz) was conducted in an acute ovine model to better understand the timing, mechanisms, and shape of aortic valve opening and closure. Methods Eighteen piezoelectric crystals were implanted in 8 sheep at each annular base, commissures, sinus of Valsalva, sinotubular junction, nodulus of Arantius, and ascending aorta (AA). Geometric changes were time related to pressures and flows. Results The aortic root was hemodynamically divided into left ventricular (LV) and aortic compartments situated, respectively, below and above the leaflets. During isovolumetric contraction (IVC), aortic root expansion started in the LV compartment, most likely due to volume redistribution in the LV outflow tract below the leaflets. This expansion initiated leaflet separation prior to ejection (2.1%±0.5% of total opening area). Aortic compartment expansion was delayed toward the end of IVC, likely related to volume redistribution above the leaflets due to accelerating aortic backflow toward the aortic valve and coronary flow reduction due to myocardial contraction. Maximum valve opening during the first third of ejection acquired a truncated cone shape [leaflet free edge area smaller than annular base area (-41.5%±5.5%)]. The distal orifice became clover shaped because the leaflet free edge area is larger than the commissural area by 16.3%±2.0%. Conclusions Aortic valve opening is initiated prior to ejection related to delicate balance between LV, aortic root, and coronary dynamics. It is clover shaped at maximum opening in systole. A better understanding of these mechanisms should stimulate more physiological surgical approaches of valve repair and replacement.
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Affiliation(s)
- Emmanuel Lansac
- Department of Cardiovascular Surgery, Institut Mutualiste Montsouris, Paris, France
| | - Hou-Sen Lim
- The International Heart Institute of Montana Foundation at St. Patrick Hospital and Health Sciences Center and The University of Montana, Missoula, Montana, USA
| | - Yu Shomura
- The International Heart Institute of Montana Foundation at St. Patrick Hospital and Health Sciences Center and The University of Montana, Missoula, Montana, USA
| | - Khee Hiang Lim
- The International Heart Institute of Montana Foundation at St. Patrick Hospital and Health Sciences Center and The University of Montana, Missoula, Montana, USA
| | - Nolan T Rice
- The International Heart Institute of Montana Foundation at St. Patrick Hospital and Health Sciences Center and The University of Montana, Missoula, Montana, USA
| | - Isabelle Di Centa
- The International Heart Institute of Montana Foundation at St. Patrick Hospital and Health Sciences Center and The University of Montana, Missoula, Montana, USA
| | - Pouya Youssefi
- Department of Cardiovascular Surgery, Institut Mutualiste Montsouris, Paris, France.,Hospital Foch, Suresnes, France
| | - Wolfgang Goetz
- The International Heart Institute of Montana Foundation at St. Patrick Hospital and Health Sciences Center and The University of Montana, Missoula, Montana, USA
| | - Carlos M G Duran
- The International Heart Institute of Montana Foundation at St. Patrick Hospital and Health Sciences Center and The University of Montana, Missoula, Montana, USA
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22
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Kurokawa R, Maeda E, Mori H, Amemiya S, Sato J, Ino K, Torigoe R, Abe O. Effect of bolus tracking region-of-interest position within the descending aorta on luminal enhancement of coronary arteries in coronary computed tomography angiography. Medicine (Baltimore) 2019; 98:e15538. [PMID: 31083207 PMCID: PMC6531088 DOI: 10.1097/md.0000000000015538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
To compare coronary artery luminal enhancement in coronary computed tomography angiography (CCTA) between ventral and dorsal region-of-interest (ROI) bolus tracking in the descending aorta.The records of 165 consecutive patients who underwent CCTA with non-helical acquisition from July 2017 to March 2018 were retrospectively examined. We performed 320-row CCTA with bolus tracking [scan triggered at 260 HU in the descending aorta] and 133 patients were finally included. ROI was set in the ventral and dorsal halves of the descending aorta in 68 and 65 patients, respectively.Contrast arrival time was significantly shorter in the dorsal group (ventral: 21.8 ± 0.372 s; dorsal: 20.7 ± 0.369; P = .0295). The mean density of the proximal and distal RCA was significantly higher in the ventral group (proximal: ventral, 428.1 ± 6.95 HU; dorsal, 405.5 ± 7.72 HU, P = .0318; distal: ventral, 418.0 ± 9.29 HU; dorsal, 393.2 ± 9.46 HU, P = .0133).Dorsal bolus tracking ROI in the descending thoracic aorta significantly reduced preparation time and RCA CT values.
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Affiliation(s)
- Ryo Kurokawa
- Department of Radiology, Graduate School of Medicine, University of Tokyo
| | - Eriko Maeda
- Department of Radiology, Graduate School of Medicine, University of Tokyo
| | - Harushi Mori
- Department of Radiology, Graduate School of Medicine, University of Tokyo
| | - Shiori Amemiya
- Department of Radiology, Graduate School of Medicine, University of Tokyo
| | - Jiro Sato
- Department of Radiology, Graduate School of Medicine, University of Tokyo
| | - Kenji Ino
- Department of Radiation Technology, University of Tokyo Hospital
| | | | - Osamu Abe
- Department of Radiology, Graduate School of Medicine, University of Tokyo
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23
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Galea N, Piatti F, Sturla F, Weinsaft JW, Lau C, Chirichilli I, Carbone I, Votta E, Catalano C, De Paulis R, Girardi LN, Redaelli A, Gaudino M. Novel insights by 4D Flow imaging on aortic flow physiology after valve-sparing root replacement with or without neosinuses. Interact Cardiovasc Thorac Surg 2019; 26:957-964. [PMID: 29401262 DOI: 10.1093/icvts/ivx431] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Accepted: 12/09/2017] [Indexed: 01/16/2023] Open
Abstract
OBJECTIVES This study was undertaken to evaluate the flow dynamics in the aortic root after valve-sparing root replacement with and without neosinuses of Valsalva reconstruction, by exploiting the capability of 4D Flow imaging to measure in vivo blood velocity fields and 3D geometric flow patterns. METHODS Ten patients who underwent valve-sparing root replacement utilizing grafts with neosinuses or straight tube grafts (5 cases each) were evaluated by 4D Flow imaging at a mean of 46.5 months after surgery. We used in-house processing tools to quantify relevant bulk flow variables (flow rate, stroke volume, peak velocity and mean velocity), wall shear stresses and the amount of flow rotation characterizing the region enclosed by the graft and the aortic valve leaflets. RESULTS Despite bulk flows with similar peak velocities, flow rates and stroke volumes (P = 0.31-1.00), the neosinuses graft was associated with a lower mean velocity (P < 0.03) and magnitude of wall shear stress along the axial direction of the vessel wall (P < 0.05) at the proximal root level but remained comparable along the circumferential direction (P = 0.22-1.0) to the straight tube graft. Flow rotation was evidently and systematically higher in the neosinuses grafts, characterized by streamline rotations higher than 270°, nearly triple that of tubular grafts (10.3 ÷ 14.0% of all aortic streamline vs 2.2 ÷ 5.7%, P = 0.008). CONCLUSIONS Recreation of the sinuses of Valsalva during valve-sparing root replacement is associated with significantly lower wall shear stress and organized vortical flows at the level of the sinus that are not evident using the straight tube graft. These findings need confirmation in larger studies and could have important implications in terms of aortic valve durability.
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Affiliation(s)
- Nicola Galea
- Department of Radiological, Oncological and Pathological Sciences, Sapienza University of Rome, Rome, Italy
| | - Filippo Piatti
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milan, Italy
| | - Francesco Sturla
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milan, Italy.,3D and Computer Simulation Laboratory, IRCCS Policlinico San Donato, San Donato Milanese, Italy
| | - Jonathan W Weinsaft
- Departments of Medicine (Cardiology), Weill Cornell Medicine, New York, NY, USA
| | - Christopher Lau
- Department of Cardiothoracic Surgery, Weill Cornell Medicine, New York, NY, USA
| | - Ilaria Chirichilli
- Department of Cardiothoracic Surgery, Weill Cornell Medicine, New York, NY, USA
| | - Iacopo Carbone
- Department of Radiological, Oncological and Pathological Sciences, Sapienza University of Rome, Rome, Italy
| | - Emiliano Votta
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milan, Italy
| | - Carlo Catalano
- Department of Radiological, Oncological and Pathological Sciences, Sapienza University of Rome, Rome, Italy
| | | | - Leonard N Girardi
- Department of Cardiothoracic Surgery, Weill Cornell Medicine, New York, NY, USA
| | - Alberto Redaelli
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milan, Italy
| | - Mario Gaudino
- Department of Cardiothoracic Surgery, Weill Cornell Medicine, New York, NY, USA
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24
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Eslami P, Seo JH, Lardo AC, Chen MY, Mittal R. Flow Dynamics in the Aortic Arch and Its Effect on the Arterial Input Function in Cardiac Computed Tomography. J Biomech Eng 2019; 141:2728067. [PMID: 30840028 DOI: 10.1115/1.4043076] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Indexed: 02/04/2023]
Abstract
The arterial input function (AIF)-time-density curve (TDC) of contrast at the coronary ostia-plays a central role in contrast enhanced computed tomography angiography (CTA). This study employs computational modeling in a patient-specific aorta to investigate mixing and dispersion of contrast in the aortic arch (AA) and to compare the TDCs in the coronary ostium and the descending aorta. Here, we examine the validity of the use of TDC in the descending aorta as a surrogate for the AIF. Computational fluid dynamics was used to study hemodynamics and contrast dispersion in a CTA-based patient model of the aorta. Variations in TDC between the aortic root, through the AA and at the descending aorta and the effect of flow patterns on contrast dispersion was studied via post-processing of the results. Simulations showed complex unsteady patterns of contrast mixing and dispersion in the AA that are driven by the pulsatile flow. However, despite the relatively long intra-aortic distance between the coronary ostia and the descending aorta, the TDCs at these two locations were similar in terms of rise-time and up-slope, and the time lag between the two TDCs was 0.19 seconds. TDC in the descending aorta is an accurate analog of the AIF. Methods that use quantitative metrics such as rise-time and slope of the AIF to estimate coronary flowrate and myocardial ischemia can continue with the current practice of using the TDC at the descending aorta as a surrogate for the AIF.
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Affiliation(s)
- Parastou Eslami
- Department of Radiology, Massachusetts General Hospital, Harvard University, Boston, MA 02114
| | - Jung-Hee Seo
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218
| | - Albert C Lardo
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21218
| | - Marcus Y Chen
- National Heart, Lung and Blood Institute (NHLBI), National Institutes of Health, Bethesda, MD 20892
| | - Rajat Mittal
- Department of Medicine, Division of Cardiology, Johns Hopkins University, Baltimore, MD 21287
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25
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Gaudino M, Piatti F, Lau C, Sturla F, Weinsaft JW, Weltert L, Votta E, Galea N, Chirichilli I, Di Franco A, Francone M, Catalano C, Redaelli A, Girardi LN, De Paulis R. Aortic flow after valve sparing root replacement with or without neosinuses reconstruction. J Thorac Cardiovasc Surg 2019; 157:455-465. [DOI: 10.1016/j.jtcvs.2018.06.094] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2018] [Revised: 06/13/2018] [Accepted: 06/24/2018] [Indexed: 01/16/2023]
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26
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Santiago A, Aguado-Sierra J, Zavala-Aké M, Doste-Beltran R, Gómez S, Arís R, Cajas JC, Casoni E, Vázquez M. Fully coupled fluid-electro-mechanical model of the human heart for supercomputers. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2018; 34:e3140. [PMID: 30117302 DOI: 10.1002/cnm.3140] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 04/28/2018] [Accepted: 07/22/2018] [Indexed: 05/12/2023]
Abstract
In this work, we present a fully coupled fluid-electro-mechanical model of a 50th percentile human heart. The model is implemented on Alya, the BSC multi-physics parallel code, capable of running efficiently in supercomputers. Blood in the cardiac cavities is modeled by the incompressible Navier-Stokes equations and an arbitrary Lagrangian-Eulerian (ALE) scheme. Electrophysiology is modeled with a monodomain scheme and the O'Hara-Rudy cell model. Solid mechanics is modeled with a total Lagrangian formulation for discrete strains using the Holzapfel-Ogden cardiac tissue material model. The three problems are simultaneously and bidirectionally coupled through an electromechanical feedback and a fluid-structure interaction scheme. In this paper, we present the scheme in detail and propose it as a computational cardiac workbench.
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Affiliation(s)
- Alfonso Santiago
- Department of Computer Applications in Science and Engineering, Barcelona Supercomputing Center (BSC), Barcelona, Spain
| | - Jazmín Aguado-Sierra
- Department of Computer Applications in Science and Engineering, Barcelona Supercomputing Center (BSC), Barcelona, Spain
| | - Miguel Zavala-Aké
- Department of Computer Applications in Science and Engineering, Barcelona Supercomputing Center (BSC), Barcelona, Spain
| | | | - Samuel Gómez
- Department of Computer Applications in Science and Engineering, Barcelona Supercomputing Center (BSC), Barcelona, Spain
| | - Ruth Arís
- Department of Computer Applications in Science and Engineering, Barcelona Supercomputing Center (BSC), Barcelona, Spain
| | - Juan C Cajas
- Department of Computer Applications in Science and Engineering, Barcelona Supercomputing Center (BSC), Barcelona, Spain
| | - Eva Casoni
- Department of Computer Applications in Science and Engineering, Barcelona Supercomputing Center (BSC), Barcelona, Spain
| | - Mariano Vázquez
- Department of Computer Applications in Science and Engineering, Barcelona Supercomputing Center (BSC), Barcelona, Spain
- Instituto de Investigación en Inteligencia Artificial (IIIA), Consejo Superior de Investigaciones Científicas (CSIC), Barcelona, Spain
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Ascending thoracic aorta aneurysm repair induces positive hemodynamic outcomes in a patient with unchanged bicuspid aortic valve. J Biomech 2018; 81:145-148. [PMID: 30340762 DOI: 10.1016/j.jbiomech.2018.09.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 09/25/2018] [Accepted: 09/25/2018] [Indexed: 11/23/2022]
Abstract
We report a patient-specific case of bicuspid aortic valve with fusion of right and left coronary leaflets (R-L type I BAV), moderate aortic valve deficiency and ascending thoracic aortic aneurysms (ATAA) who was treated by only ascending aorta replacement preserving the BAV. The flow eccentricity, the helicity intensity (h2), the circumferential time averaged wall shear stress (TAWSScircumferential), the cumulative viscous energy loss at the systolic peak (EL') and the pulse wave velocity (PWV) were calculated by combining 4D flow MRI and CFD analysis before (Stage I) and after (Stage II) the surgical procedure. CFD analyses assumed rigid walls, a non-Newtonian behavior for the blood and MRI measured patient-specific blood flow profiles as inlet boundary conditions. Stage II results showed suppression of recirculation in the ascending aorta, loss of jet flow impingement onto the aortic wall, maximum TAWSScircumferential decrease (from 6.69 Pa in Stage I to 6 Pa in Stage II), reduction of flow helicity (from 10.97 in Stage I to 8.47 in Stage II) and EL' (from 15.8 mW in Stage I to 11.2 mW in Stage II). However, Floweccentricity and PWV were found higher in Stage II due to the diameter reduction (Floweccentricity = 0.60 in Stage I and Floweccentricity = 0.91 in Stage II; PWV = 3.80 m/s in Stage I and PWV = 9.37 m/s in Stage II). Our work has permitted to compute for the first time the hemodynamic alterations obtained after restoration of normal ascending aorta and sinotubular junction geometry even preserving an R-L type I BAV with still acceptable function.
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Siedek F, Giese D, Weiss K, Ekdawi S, Brinkmann S, Schroeder W, Bruns C, Chang DH, Persigehl T, Maintz D, Haneder S. 4D flow MRI for the analysis of celiac trunk and mesenteric artery stenoses. Magn Reson Imaging 2018; 53:52-62. [PMID: 30008436 DOI: 10.1016/j.mri.2018.06.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Revised: 05/31/2018] [Accepted: 06/28/2018] [Indexed: 01/13/2023]
Abstract
PURPOSE This study aims to assess the feasibility of 4D flow MRI measurements in complex vascular territories; namely, the celiac artery (CA) and superior mesenteric artery (SMA). MATERIALS AND METHODS In this prospective study, 22 healthy volunteers and 10 patients were scanned at 3 T. Blood flow parameters were compared between healthy volunteers and patients with stenosis of the CA and/or SMA as a function of stenosis grade characterized by prior contrast-enhanced computed tomography (CE-CT). The 4D flow MRI acquisition covered the CA, SMA and adjusting parts of the abdominal aorta (AO). Measurements of velocity- (peak velocity [PV], average velocity [AV]) and volume-related parameters (peak flow [PF], stroke volume [SV]) were conducted. Further, stenosis grade and wall shear stress in the CA, SMA and AO were evaluated. RESULTS In patients, prior evaluation by CE-CT revealed 11 low- and 5 mid-grade stenoses of the CA and/or SMA. PV and AV were significantly higher in patients than in healthy volunteers [PV: p < 0.0001; AV: p = 0.03, p < 0.001]. PF and SV did not differ significantly between healthy volunteers and patients; however, a trend towards lower PF and SV could be detected in patients with mid-grade stenoses. Comparison of 4D flow MRI with CE-CT revealed a strong positive correlation in estimated degree of stenosis (CA: r = 0.86, SMA: r = 0.98). Patients with mid-grade stenoses had a significantly higher average WSS magnitude (AWM) than healthy volunteers (p = 0.02). CONCLUSION This feasibility study suggests that 4D flow MRI is a viable technique for the evaluation of complex flow characteristics in small vessels such as the CA and SMA. 4D flow MRI approves comparable to the morphologic assessment of complex vascular territories using CE-CT but, in addition, offers the functional evaluation of flow parameters that goes beyond the morphology.
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Affiliation(s)
- Florian Siedek
- Institute of Diagnostic and Interventional Radiology, University of Cologne, Kerpener Str. 62, 50937 Cologne, Germany.
| | - Daniel Giese
- Institute of Diagnostic and Interventional Radiology, University of Cologne, Kerpener Str. 62, 50937 Cologne, Germany
| | - Kilian Weiss
- Institute of Diagnostic and Interventional Radiology, University of Cologne, Kerpener Str. 62, 50937 Cologne, Germany; Philips Healthcare Germany, Hamburg, Germany
| | - Sandra Ekdawi
- Institute of Diagnostic and Interventional Radiology, University of Cologne, Kerpener Str. 62, 50937 Cologne, Germany
| | - Sebastian Brinkmann
- Department of General, Visceral and Tumor Surgery, University of Cologne, Kerpener Str. 62, 50937 Cologne, Germany
| | - Wolfgang Schroeder
- Department of General, Visceral and Tumor Surgery, University of Cologne, Kerpener Str. 62, 50937 Cologne, Germany
| | - Christiane Bruns
- Department of General, Visceral and Tumor Surgery, University of Cologne, Kerpener Str. 62, 50937 Cologne, Germany
| | - De-Hua Chang
- Institute of Diagnostic and Interventional Radiology, University of Cologne, Kerpener Str. 62, 50937 Cologne, Germany
| | - Thorsten Persigehl
- Institute of Diagnostic and Interventional Radiology, University of Cologne, Kerpener Str. 62, 50937 Cologne, Germany
| | - David Maintz
- Institute of Diagnostic and Interventional Radiology, University of Cologne, Kerpener Str. 62, 50937 Cologne, Germany
| | - Stefan Haneder
- Institute of Diagnostic and Interventional Radiology, University of Cologne, Kerpener Str. 62, 50937 Cologne, Germany
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Liu D, Fan Z, Li Y, Zhang N, Sun Z, An J, Stalder AF, Greiser A, Liu J. Quantitative Study of Abdominal Blood Flow Patterns in Patients with Aortic Dissection by 4-Dimensional Flow MRI. Sci Rep 2018; 8:9111. [PMID: 29904131 PMCID: PMC6002546 DOI: 10.1038/s41598-018-27249-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 05/31/2018] [Indexed: 11/09/2022] Open
Abstract
The purpose of this study is to evaluate the hemodynamic characteristics of the true lumen (TL) and the false lumen (FL) in 16 patients with aortic dissection (AD) using 4D flow magnetic resonance imaging (MRI) and thoracic and abdominal computed tomography (CT) angiography. The quantitative parameters that were measured in the TL and FL included velocity and flow. The mean area and regurgitant fraction of the TL were significantly lesser at all four levels (p < 0.05); the average through-plane velocity, peak velocity magnitude, average net flow, peak flow, and net forward volume in the TL were considerably higher (p < 0.05). The intimal entry's size was negatively correlated with the blood flow velocity and flow rate in the TL (p < 0.05) and positively correlated with the average through-plane velocity, average net flow, and peak flow in the FL (p < 0.05); the blood flow indices in the TL were enhanced with an increase in the intimal entry numbers (p < 0.05) and the peak flow in the FL was lowered (p = 0.025); if FL thrombosis existed, the average through-plane velocity and peak velocity magnitude in the TL were substantially higher (p < 0.05). 4D flow MRI facilitates qualitative and quantitative analysis of the alterations in the abdominal aortic blood flow patterns.
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Affiliation(s)
- Dongting Liu
- Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, Beijing, 100029, China
| | - Zhanming Fan
- Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, Beijing, 100029, China
| | - Yu Li
- Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, Beijing, 100029, China
| | - Nan Zhang
- Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, Beijing, 100029, China
| | - Zhonghua Sun
- Department of Medical Radiation Sciences, Curtin University, Perth, 6102, Australia
| | - Jing An
- Siemens Shenzhen Magnetic Resonance Ltd, Beijing, China
| | | | | | - Jiayi Liu
- Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, Beijing, 100029, China.
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Galea N, Piatti F, Lau C, Sturla F, Weltert L, Carbone I, De Paulis R, Gaudino M, Girardi LN. 4D flow characterization of aortic blood flow after valve sparing root reimplantation procedure. J Vis Surg 2018; 4:95. [PMID: 29963384 DOI: 10.21037/jovs.2018.03.17] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2018] [Accepted: 03/15/2018] [Indexed: 11/06/2022]
Abstract
Valve-sparing aortic root replacement (VSRR) with reimplantation technique is an effective alternative for young patients with dilated roots and preserved cusps, which avoids the risks of lifelong anticoagulation or valve degeneration. New grafts with anatomically-shaped sinuses have been developed in order to preserve aortic root physiology, which could decrease complication rates and improve durability. However, controversy remains regarding the effect of recreation of the sinuses of Valsalva during VSRR on long-term outcomes. The novel 4D flow technique, exploiting its unique ability to combine anatomical evaluation of the root with fluid-dynamic assessment of aortic flow, enables integrated analysis of the close interaction between graft design, valvular morphology and three-dimensional (3D) flow characteristics. Early experimental studies have shown how graft shape affects the aortic root flow pattern, formation of vortexes and helicity of downstream flow; however, the clinical significance of these findings is yet to be clarified. Various and still unexplored knowledge can be obtained from the qualitative and quantitative analysis of these complex datasets, that could shed more light on which is the best among myriad surgical techniques and grafts adopted in VSRR. The extraordinary potential 4D flow imaging opens new boundless horizons in the perspective of an increasingly patient-tailored surgical planning.
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Affiliation(s)
- Nicola Galea
- Department of Experimental Medicine, Oncological and Pathological Sciences, Sapienza University of Rome, Rome, Italy.,Department of Radiological, Oncological and Pathological Sciences, Sapienza University of Rome, Rome, Italy
| | - Filippo Piatti
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milan, Italy
| | - Christopher Lau
- Department of Cardiothoracic Surgery, Weill Cornell Medicine, New York, USA
| | - Francesco Sturla
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milan, Italy.,3D and Computer Simulation Laboratory, IRCCS Policlinico San Donato, San Donato Milanese, Italy
| | - Luca Weltert
- Department of Cardiac Surgery, European Hospital, Rome, Italy
| | - Iacopo Carbone
- Department of Radiological, Oncological and Pathological Sciences, Sapienza University of Rome, Rome, Italy
| | | | - Mario Gaudino
- Department of Cardiothoracic Surgery, Weill Cornell Medicine, New York, USA
| | - Leonard N Girardi
- Department of Cardiothoracic Surgery, Weill Cornell Medicine, New York, USA
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Hasler D, Obrist D. Three-dimensional flow structures past a bio-prosthetic valve in an in-vitro model of the aortic root. PLoS One 2018; 13:e0194384. [PMID: 29547668 PMCID: PMC5856406 DOI: 10.1371/journal.pone.0194384] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Accepted: 03/04/2018] [Indexed: 12/18/2022] Open
Abstract
The flow field past a prosthetic aortic valve comprises many details that indicate whether the prosthesis is functioning well or not. It is, however, not yet fully understood how an optimal flow scenario would look, i.e. which subtleties of the fluid dynamics in place are essential regarding the durability and compatibility of a prosthetic valve. In this study, we measured and analyzed the 3D flow field in the vicinity of a bio-prosthetic heart valve in function of the aortic root size. The measurements were conducted within aortic root phantoms of different size, mounted in a custom-built hydraulic setup, which mimicked physiological flow conditions in the aorta. Tomographic particle image velocimetry was used to measure the 3D instantaneous velocity field at various instances. Several 3D fields (e.g. instantaneous and mean velocity, 3D shear rate) were analyzed and compared focusing on the impact of the aortic root size, but also in order to gain general insight in the 3D flow structure past the bio-prosthetic valve. We found that the diameter of the aortic jet relative to the diameter of the ascending aorta is the most important parameter in determining the characteristics of the flow. A large aortic cross-section, relative to the cross-section of the aortic jet, was associated with higher levels of turbulence intensity and higher retrograde flow in the ascending aorta.
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Affiliation(s)
- David Hasler
- ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
| | - Dominik Obrist
- ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
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Wehrum T, Guenther F, Fuchs A, Schuchardt F, Hennemuth A, Harloff A. Measurement of cardiac valve and aortic blood flow velocities in stroke patients: a comparison of 4D flow MRI and echocardiography. Int J Cardiovasc Imaging 2018; 34:939-946. [DOI: 10.1007/s10554-018-1298-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Accepted: 01/04/2018] [Indexed: 11/30/2022]
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Midha PA, Raghav V, Sharma R, Condado JF, Okafor IU, Rami T, Kumar G, Thourani VH, Jilaihawi H, Babaliaros V, Makkar RR, Yoganathan AP. The Fluid Mechanics of Transcatheter Heart Valve Leaflet Thrombosis in the Neosinus. Circulation 2017; 136:1598-1609. [PMID: 28724752 DOI: 10.1161/circulationaha.117.029479] [Citation(s) in RCA: 156] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 07/11/2017] [Indexed: 11/16/2022]
Abstract
BACKGROUND Transcatheter heart valve (THV) thrombosis has been increasingly reported. In these studies, thrombus quantification has been based on a 2-dimensional assessment of a 3-dimensional phenomenon. METHODS Postprocedural, 4-dimensional, volume-rendered CT data of patients with CoreValve, Evolut R, and SAPIEN 3 transcatheter aortic valve replacement enrolled in the RESOLVE study (Assessment of Transcatheter and Surgical Aortic Bioprosthetic Valve Dysfunction With Multimodality Imaging and Its Treatment with Anticoagulation) were included in this analysis. Patients on anticoagulation were excluded. SAPIEN 3 and CoreValve/Evolut R patients with and without hypoattenuated leaflet thickening were included to study differences between groups. Patients were classified as having THV thrombosis if there was any evidence of hypoattenuated leaflet thickening. Anatomic and THV deployment geometries were analyzed, and thrombus volumes were computed through manual 3-dimensional reconstruction. We aimed to identify and evaluate risk factors that contribute to THV thrombosis through the combination of retrospective clinical data analysis and in vitro imaging in the space between the native and THV leaflets (neosinus). RESULTS SAPIEN 3 valves with leaflet thrombosis were on average 10% further expanded (by diameter) than those without (95.5±5.2% versus 85.4±3.9%; P<0.001). However, this relationship was not evident with the CoreValve/Evolut R. In CoreValve/Evolut Rs with thrombosis, the thrombus volume increased linearly with implant depth (R2=0.7, P<0.001). This finding was not seen in the SAPIEN 3. The in vitro analysis showed that a supraannular THV deployment resulted in a nearly 7-fold decrease in stagnation zone size (velocities <0.1 m/s) when compared with an intraannular deployment. In addition, the in vitro model indicated that the size of the stagnation zone increased as cardiac output decreased. CONCLUSIONS Although transcatheter aortic valve replacement thrombosis is a multifactorial process involving foreign materials, patient-specific blood chemistry, and complex flow patterns, our study indicates that deployed THV geometry may have implications on the occurrence of thrombosis. In addition, a supraannular neosinus may reduce thrombosis risk because of reduced flow stasis. Although additional prospective studies are needed to further develop strategies for minimizing thrombus burden, these results may help identify patients at higher thrombosis risk and aid in the development of next-generation devices with reduced thrombosis risk.
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Affiliation(s)
- Prem A Midha
- From Georgia Institute of Technology, Atlanta (P.A.M., V.R., I.U.O., A.P.Y.); Cedars-Sinai Heart Institute, Los Angeles, CA (R.S., T.R., R.R.M.); Emory University, Atlanta, GA (J.F.C., G.K., V.H.T., V.B.); Exponent, Inc., Philadelphia, PA (I.U.O.); Atlanta Veterans Affairs Medical Center, Decatur, GA (G.K.); and New York University Langone Medical Center (H.J.)
| | - Vrishank Raghav
- From Georgia Institute of Technology, Atlanta (P.A.M., V.R., I.U.O., A.P.Y.); Cedars-Sinai Heart Institute, Los Angeles, CA (R.S., T.R., R.R.M.); Emory University, Atlanta, GA (J.F.C., G.K., V.H.T., V.B.); Exponent, Inc., Philadelphia, PA (I.U.O.); Atlanta Veterans Affairs Medical Center, Decatur, GA (G.K.); and New York University Langone Medical Center (H.J.)
| | - Rahul Sharma
- From Georgia Institute of Technology, Atlanta (P.A.M., V.R., I.U.O., A.P.Y.); Cedars-Sinai Heart Institute, Los Angeles, CA (R.S., T.R., R.R.M.); Emory University, Atlanta, GA (J.F.C., G.K., V.H.T., V.B.); Exponent, Inc., Philadelphia, PA (I.U.O.); Atlanta Veterans Affairs Medical Center, Decatur, GA (G.K.); and New York University Langone Medical Center (H.J.)
| | - Jose F Condado
- From Georgia Institute of Technology, Atlanta (P.A.M., V.R., I.U.O., A.P.Y.); Cedars-Sinai Heart Institute, Los Angeles, CA (R.S., T.R., R.R.M.); Emory University, Atlanta, GA (J.F.C., G.K., V.H.T., V.B.); Exponent, Inc., Philadelphia, PA (I.U.O.); Atlanta Veterans Affairs Medical Center, Decatur, GA (G.K.); and New York University Langone Medical Center (H.J.)
| | - Ikechukwu U Okafor
- From Georgia Institute of Technology, Atlanta (P.A.M., V.R., I.U.O., A.P.Y.); Cedars-Sinai Heart Institute, Los Angeles, CA (R.S., T.R., R.R.M.); Emory University, Atlanta, GA (J.F.C., G.K., V.H.T., V.B.); Exponent, Inc., Philadelphia, PA (I.U.O.); Atlanta Veterans Affairs Medical Center, Decatur, GA (G.K.); and New York University Langone Medical Center (H.J.)
| | - Tanya Rami
- From Georgia Institute of Technology, Atlanta (P.A.M., V.R., I.U.O., A.P.Y.); Cedars-Sinai Heart Institute, Los Angeles, CA (R.S., T.R., R.R.M.); Emory University, Atlanta, GA (J.F.C., G.K., V.H.T., V.B.); Exponent, Inc., Philadelphia, PA (I.U.O.); Atlanta Veterans Affairs Medical Center, Decatur, GA (G.K.); and New York University Langone Medical Center (H.J.)
| | - Gautam Kumar
- From Georgia Institute of Technology, Atlanta (P.A.M., V.R., I.U.O., A.P.Y.); Cedars-Sinai Heart Institute, Los Angeles, CA (R.S., T.R., R.R.M.); Emory University, Atlanta, GA (J.F.C., G.K., V.H.T., V.B.); Exponent, Inc., Philadelphia, PA (I.U.O.); Atlanta Veterans Affairs Medical Center, Decatur, GA (G.K.); and New York University Langone Medical Center (H.J.)
| | - Vinod H Thourani
- From Georgia Institute of Technology, Atlanta (P.A.M., V.R., I.U.O., A.P.Y.); Cedars-Sinai Heart Institute, Los Angeles, CA (R.S., T.R., R.R.M.); Emory University, Atlanta, GA (J.F.C., G.K., V.H.T., V.B.); Exponent, Inc., Philadelphia, PA (I.U.O.); Atlanta Veterans Affairs Medical Center, Decatur, GA (G.K.); and New York University Langone Medical Center (H.J.)
| | - Hasan Jilaihawi
- From Georgia Institute of Technology, Atlanta (P.A.M., V.R., I.U.O., A.P.Y.); Cedars-Sinai Heart Institute, Los Angeles, CA (R.S., T.R., R.R.M.); Emory University, Atlanta, GA (J.F.C., G.K., V.H.T., V.B.); Exponent, Inc., Philadelphia, PA (I.U.O.); Atlanta Veterans Affairs Medical Center, Decatur, GA (G.K.); and New York University Langone Medical Center (H.J.)
| | - Vasilis Babaliaros
- From Georgia Institute of Technology, Atlanta (P.A.M., V.R., I.U.O., A.P.Y.); Cedars-Sinai Heart Institute, Los Angeles, CA (R.S., T.R., R.R.M.); Emory University, Atlanta, GA (J.F.C., G.K., V.H.T., V.B.); Exponent, Inc., Philadelphia, PA (I.U.O.); Atlanta Veterans Affairs Medical Center, Decatur, GA (G.K.); and New York University Langone Medical Center (H.J.)
| | - Raj R Makkar
- From Georgia Institute of Technology, Atlanta (P.A.M., V.R., I.U.O., A.P.Y.); Cedars-Sinai Heart Institute, Los Angeles, CA (R.S., T.R., R.R.M.); Emory University, Atlanta, GA (J.F.C., G.K., V.H.T., V.B.); Exponent, Inc., Philadelphia, PA (I.U.O.); Atlanta Veterans Affairs Medical Center, Decatur, GA (G.K.); and New York University Langone Medical Center (H.J.)
| | - Ajit P Yoganathan
- From Georgia Institute of Technology, Atlanta (P.A.M., V.R., I.U.O., A.P.Y.); Cedars-Sinai Heart Institute, Los Angeles, CA (R.S., T.R., R.R.M.); Emory University, Atlanta, GA (J.F.C., G.K., V.H.T., V.B.); Exponent, Inc., Philadelphia, PA (I.U.O.); Atlanta Veterans Affairs Medical Center, Decatur, GA (G.K.); and New York University Langone Medical Center (H.J.).
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Montalba C, Urbina J, Sotelo J, Andia ME, Tejos C, Irarrazaval P, Hurtado DE, Valverde I, Uribe S. Variability of 4D flow parameters when subjected to changes in MRI acquisition parameters using a realistic thoracic aortic phantom. Magn Reson Med 2017; 79:1882-1892. [DOI: 10.1002/mrm.26834] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 06/02/2017] [Accepted: 06/19/2017] [Indexed: 01/28/2023]
Affiliation(s)
- Cristian Montalba
- Biomedical Imaging CenterPontificia Universidad Católica de ChileSantiago Chile
| | - Jesus Urbina
- Biomedical Imaging CenterPontificia Universidad Católica de ChileSantiago Chile
- Department of RadiologySchool of Medicine, Pontificia Universidad Católica de ChileSantiago Chile
| | - Julio Sotelo
- Biomedical Imaging CenterPontificia Universidad Católica de ChileSantiago Chile
- Department of Electrical EngineeringPontificia Universidad Católica de ChileSantiago Chile
| | - Marcelo E. Andia
- Biomedical Imaging CenterPontificia Universidad Católica de ChileSantiago Chile
- Department of RadiologySchool of Medicine, Pontificia Universidad Católica de ChileSantiago Chile
| | - Cristian Tejos
- Biomedical Imaging CenterPontificia Universidad Católica de ChileSantiago Chile
- Department of Electrical EngineeringPontificia Universidad Católica de ChileSantiago Chile
| | - Pablo Irarrazaval
- Biomedical Imaging CenterPontificia Universidad Católica de ChileSantiago Chile
- Department of Electrical EngineeringPontificia Universidad Católica de ChileSantiago Chile
| | - Daniel E. Hurtado
- Department of Structural and Geotechnical EngineeringPontificia Universidad Católica de ChileSantiago Chile
- Institute for Biological and Medical EngineeringSchools of Engineering, Medicine and Biological Sciences, Pontificia Universidad Católica de ChileSantiago Chile
| | - Israel Valverde
- Hospital Virgen del RocioUniversidad de SevillaSeville Spain
- Institute of Biomedicine of SevilleUniversidad de SevillaSeville Spain
| | - Sergio Uribe
- Biomedical Imaging CenterPontificia Universidad Católica de ChileSantiago Chile
- Department of RadiologySchool of Medicine, Pontificia Universidad Católica de ChileSantiago Chile
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Large eddy simulations of blood dynamics in abdominal aortic aneurysms. Med Eng Phys 2017; 47:38-46. [PMID: 28709929 DOI: 10.1016/j.medengphy.2017.06.030] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 06/02/2017] [Accepted: 06/14/2017] [Indexed: 02/07/2023]
Abstract
We study the effects of transition to turbulence in abdominal aortic aneurysms (AAA). The presence of transitional effects in such districts is related to the heart pulsatility and the sudden change of diameter of the vessels, and has been recorded by means of clinical measures as well as of computational studies. Here we propose, for the first time, the use of a large eddy simulation (LES) model to accurately describe transition to turbulence in realistic scenarios of AAA obtained from radiological images. To this aim, we post-process the obtained numerical solutions to assess significant quantities, such as the ensemble-averaged velocity and wall shear stress, the standard deviation of the fluctuating velocity field, and vortical structures educed via the so-called Q-criterion. The results demonstrate the suitability of the considered LES model and show the presence of significant transitional effects around the impingement region during the mid-deceleration phase.
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Oster J, Clifford GD. Acquisition of electrocardiogram signals during magnetic resonance imaging. Physiol Meas 2017; 38:R119-R142. [PMID: 28430109 DOI: 10.1088/1361-6579/aa6e8c] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The recording of the electrocardiogram (ECG) during magnetic resonance imaging (MRI) acquisition is of great interest and importance. Firstly, MRI acquisition is a relatively slow process, which therefore complicates the imaging of moving organs. Cardiac MRI requires the development of strategies for acquiring high quality images, which is mainly achieved by synchronising the image acquisition with a specific time during the cardiac cycle. The ECG is used to monitor the heart's activity, and the detection of the largest and steepest peak in the cardiac cycle (the QRS complex) triggers the acquisition of slices of the k-space. Secondly, patients undergoing an MRI examination need to be monitored for safety during the procedure, and therefore ECG signals are used to track their cardiovascular state in real time. However, there are significant barriers to the accurate observation and processing of the ECG during MRI acquisition. In particular, the flow of charged blood particles through the large applied magnetic field leads to an extra current source, known as the magnetohdrodymanic (MHD) effect. This review article discusses these barriers and state-of-the-art solutions. An overview of the relevant technology including hardware and applications are described. The development of new software tools for the processing of the ECG signals acquired during MRI is also detailed. These developments include the design of specific QRS detection algorithms, which are able to distinguish QRS complexes from the MHD effect but also the gradient artefacts. Different techniques for the suppression of the gradient artefacts are also presented as well as the most challenging problem to-date-the problem of separating the MHD effect from the ECG. The article concludes by summarising the advantages of using ECG signals during MRI, but also presents the current limitations of modern analysis techniques in this domain. The most promising avenues of research are also discussed and suggestions for new methodological analyses for the development of this field are given.
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Affiliation(s)
- Julien Oster
- IADI, U947, INSERM, Université de Lorraine, CHRU Nancy, Vandoeuvre-les-Nancy, France
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Sotelo J, Urbina J, Valverde I, Mura J, Tejos C, Irarrazaval P, Andia ME, Hurtado DE, Uribe S. Three-dimensional quantification of vorticity and helicity from 3D cine PC-MRI using finite-element interpolations. Magn Reson Med 2017; 79:541-553. [DOI: 10.1002/mrm.26687] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 03/01/2017] [Accepted: 03/05/2017] [Indexed: 11/07/2022]
Affiliation(s)
- Julio Sotelo
- Biomedical Imaging Center; Pontificia Universidad Católica de Chile; Santiago Chile
- Department of Electrical Engineering; Pontificia Universidad Católica de Chile; Santiago Chile
- Department of Structural and Geotechnical Engineering; Pontificia Universidad Católica de Chile; Santiago Chile
| | - Jesús Urbina
- Biomedical Imaging Center; Pontificia Universidad Católica de Chile; Santiago Chile
- Department of Radiology; School of Medicine, Pontificia Universidad Católica de Chile; Santiago Chile
| | - Israel Valverde
- Pediatric Cardiology Unit; Hospital Virgen del Rocio; Sevilla Spain
- Cardiovascular Pathology Unit; Institute of Biomedicine of Seville (IBIS), Hospital Virgen del Rocio; Sevilla Spain
| | - Joaquín Mura
- Biomedical Imaging Center; Pontificia Universidad Católica de Chile; Santiago Chile
| | - Cristián Tejos
- Biomedical Imaging Center; Pontificia Universidad Católica de Chile; Santiago Chile
- Department of Electrical Engineering; Pontificia Universidad Católica de Chile; Santiago Chile
- Institute for Biological and Medical Engineering; Schools of Engineering, Medicine and Biological Sciences, Pontificia Universidad Católica de Chile; Santaigo Chile
| | - Pablo Irarrazaval
- Biomedical Imaging Center; Pontificia Universidad Católica de Chile; Santiago Chile
- Department of Electrical Engineering; Pontificia Universidad Católica de Chile; Santiago Chile
- Institute for Biological and Medical Engineering; Schools of Engineering, Medicine and Biological Sciences, Pontificia Universidad Católica de Chile; Santaigo Chile
| | - Marcelo E. Andia
- Biomedical Imaging Center; Pontificia Universidad Católica de Chile; Santiago Chile
- Department of Radiology; School of Medicine, Pontificia Universidad Católica de Chile; Santiago Chile
- Institute for Biological and Medical Engineering; Schools of Engineering, Medicine and Biological Sciences, Pontificia Universidad Católica de Chile; Santaigo Chile
| | - Daniel E. Hurtado
- Department of Structural and Geotechnical Engineering; Pontificia Universidad Católica de Chile; Santiago Chile
- Institute for Biological and Medical Engineering; Schools of Engineering, Medicine and Biological Sciences, Pontificia Universidad Católica de Chile; Santaigo Chile
| | - Sergio Uribe
- Biomedical Imaging Center; Pontificia Universidad Católica de Chile; Santiago Chile
- Department of Radiology; School of Medicine, Pontificia Universidad Católica de Chile; Santiago Chile
- Institute for Biological and Medical Engineering; Schools of Engineering, Medicine and Biological Sciences, Pontificia Universidad Católica de Chile; Santaigo Chile
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Krämer M, Motaal AG, Herrmann KH, Löffler B, Reichenbach JR, Strijkers GJ, Hoerr V. Cardiac 4D phase-contrast CMR at 9.4 T using self-gated ultra-short echo time (UTE) imaging. J Cardiovasc Magn Reson 2017; 19:39. [PMID: 28359292 PMCID: PMC5374606 DOI: 10.1186/s12968-017-0351-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Accepted: 03/02/2017] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Time resolved 4D phase contrast (PC) cardiovascular magnetic resonance (CMR) in mice is challenging due to long scan times, small animal ECG-gating and the rapid blood flow and cardiac motion of small rodents. To overcome several of these technical challenges we implemented a retrospectively self-gated 4D PC radial ultra-short echo-time (UTE) acquisition scheme and assessed its performance in healthy mice by comparing the results with those obtained with an ECG-triggered 4D PC fast low angle shot (FLASH) sequence. METHODS Cardiac 4D PC CMR images were acquired at 9.4 T in healthy mice using the proposed self-gated radial center-out UTE acquisition scheme (TE/TR of 0.5 ms/3.1 ms) and a standard Cartesian 4D PC imaging sequence (TE/TR of 2.1 ms/5.0 ms) with a four-point Hadamard flow encoding scheme. To validate the proposed UTE flow imaging technique, experiments on a flow phantom with variable pump rates were performed. RESULTS The anatomical images and flow velocity maps of the proposed 4D PC UTE technique showed reduced artifacts and an improved SNR (left ventricular cavity (LV): 8.9 ± 2.5, myocardium (MC): 15.7 ± 1.9) compared to those obtained using a typical Cartesian FLASH sequence (LV: 5.6 ± 1.2, MC: 10.1 ± 1.4) that was used as a reference. With both sequences comparable flow velocities were obtained in the flow phantom as well as in the ascending aorta (UTE: 132.8 ± 18.3 cm/s, FLASH: 134.7 ± 13.4 cm/s) and pulmonary artery (UTE: 78.5 ± 15.4 cm/s, FLASH: 86.6 ± 6.2 cm/s) of the animals. Self-gated navigator signals derived from information of the oversampled k-space center were successfully extracted for all animals with a higher gating efficiency of time spent on acquiring gated data versus total measurement time (UTE: 61.8 ± 11.5%, FLASH: 48.5 ± 4.9%). CONCLUSIONS The proposed self-gated 4D PC UTE sequence enables robust and accurate flow velocity mapping of the mouse heart in vivo at high magnetic fields. At the same time SNR, gating efficiency, flow artifacts and image quality all improved compared to the images obtained using the well-established, ECG-triggered, 4D PC FLASH sequence.
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Affiliation(s)
- M. Krämer
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology, Jena University Hospital - Friedrich Schiller University Jena, Philosophenweg 3, D-07743 Jena, Germany
| | - A. G. Motaal
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands
| | - K-H. Herrmann
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology, Jena University Hospital - Friedrich Schiller University Jena, Philosophenweg 3, D-07743 Jena, Germany
| | - B. Löffler
- Institute of Medical Microbiology, Jena University Hospital, Friedrich Schiller University Jena, Jena, Germany
| | - J. R. Reichenbach
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology, Jena University Hospital - Friedrich Schiller University Jena, Philosophenweg 3, D-07743 Jena, Germany
- Michael Stifel Center for Data-driven and Simulation Science Jena, Friedrich Schiller University Jena, Jena, Germany
- Abbe School of Photonics, Friedrich Schiller University Jena, Jena, Germany
- Center of Medical Optics and Photonics, Friedrich Schiller University Jena, Jena, Germany
| | - G. J. Strijkers
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands
- Biomedical Engineering and Physics, Academic Medical Center, Amsterdam, Netherlands
| | - V. Hoerr
- Institute of Medical Microbiology, Jena University Hospital, Friedrich Schiller University Jena, Jena, Germany
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A posteriori accuracy estimation of ultrasonic vector-flow mapping (VFM). J Vis (Tokyo) 2017; 20:607-623. [PMID: 28794685 PMCID: PMC5522659 DOI: 10.1007/s12650-016-0413-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 11/12/2016] [Accepted: 12/12/2016] [Indexed: 12/05/2022]
Abstract
Abstract A novel method, called a posteriori “VFM accuracy estimation” (VAE), for resolving an intrinsic VFM problem is proposed. The problem is that VFM uncertainty can easily vary according to blood flows through an echocardiographic imaged plane (i.e., “through-plane” flows), and it is unknown. Knowing the VFM uncertainty for each patient will make it possible to refine the quality of VFM-based diagnosis. In the present study, VAE was derived on the basis of an error-propagation analysis and a statistical analysis. The accuracy of VAE with a pulsatile left-ventricle phantom was experimentally investigated for realistic cases with through-plane flows. VAE was validated by comparing VFM uncertainty (S.D.) estimated by VAE with VFM uncertainty measured by particle-image velocimetry (PIV) for different imaged planes. VAE accurately estimated the S.D. of VFM uncertainty measured by PIV for all cases with different image planes (R > 0.6 and p < 0.001). These findings on VFM accuracy will provide the basis for widespread clinical application of VFM-based diagnosis. Graphical Abstract ![]()
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Fouquet O, Baufreton C, Tassin A, Pinaud F, Binuani JP, DangVan S, Prunier F, Rouleau F, Willoteaux S, De Brux JL, Furber A. Influence of stentless versus stented valves on ventricular remodeling assessed at 6 months by magnetic resonance imaging and long-term follow-up. J Cardiol 2017; 69:264-271. [DOI: 10.1016/j.jjcc.2016.04.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Revised: 03/25/2016] [Accepted: 04/19/2016] [Indexed: 10/21/2022]
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Toninato R, Salmon J, Susin FM, Ducci A, Burriesci G. Physiological vortices in the sinuses of Valsalva: An in vitro approach for bio-prosthetic valves. J Biomech 2016; 49:2635-2643. [PMID: 27282961 PMCID: PMC5061069 DOI: 10.1016/j.jbiomech.2016.05.027] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 04/24/2016] [Accepted: 05/24/2016] [Indexed: 11/23/2022]
Abstract
PURPOSE The physiological flow dynamics within the Valsalva sinuses, in terms of global and local parameters, are still not fully understood. This study attempts to identify the physiological conditions as closely as possible, and to give an explanation of the different and sometime contradictory results in literature. METHODS An in vitro approach was implemented for testing porcine bio-prosthetic valves operating within different aortic root configurations. All tests were performed on a pulse duplicator, under physiological pressure and flow conditions. The fluid dynamics established in the various cases were analysed by means of 2D Particle Image Velocimetry, and related with the achieved hydrodynamic performance. RESULTS Each configuration is associated with substantially different flow dynamics, which significantly affects the valve performance. The configuration most closely replicating healthy native anatomy was characterised by the best hemodynamic performance, and any mismatch in size and position between the valve and the root produced substantial modification of the fluid dynamics downstream of the valve, hindering the hydrodynamic performance of the system. The worst conditions were observed for a configuration characterised by the total absence of the Valsalva sinuses. CONCLUSION This study provides an explanation for the different vortical structures described in the literature downstream of bioprosthetic valves, enlightening the experimental complications in valve testing. Most importantly, the results clearly identify the fluid mechanisms promoted by the Valsalva sinuses to enhance the ejection and closing phases, and this study exposes the importance of an optimal integration of the valve and root, to operate as a single system.
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Affiliation(s)
- Riccardo Toninato
- UCL Cardiovascular Engineering Laboratory, UCL Mechanical Engineering, University College London, UK; Cardiovascular Fluid Dynamics Laboratory HER, Department of Civil, Environmental and Architectural Engineering - University of Padua, Italy
| | - Jacob Salmon
- UCL Cardiovascular Engineering Laboratory, UCL Mechanical Engineering, University College London, UK
| | - Francesca Maria Susin
- Cardiovascular Fluid Dynamics Laboratory HER, Department of Civil, Environmental and Architectural Engineering - University of Padua, Italy
| | - Andrea Ducci
- UCL Cardiovascular Engineering Laboratory, UCL Mechanical Engineering, University College London, UK
| | - Gaetano Burriesci
- UCL Cardiovascular Engineering Laboratory, UCL Mechanical Engineering, University College London, UK.
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Oechtering TH, Hons CF, Sieren M, Hunold P, Hennemuth A, Huellebrand M, Drexl J, Scharfschwerdt M, Richardt D, Sievers HH, Barkhausen J, Frydrychowicz A. Time-resolved 3-dimensional magnetic resonance phase contrast imaging (4D Flow MRI) analysis of hemodynamics in valve-sparing aortic root repair with an anatomically shaped sinus prosthesis. J Thorac Cardiovasc Surg 2016; 152:418-427.e1. [DOI: 10.1016/j.jtcvs.2016.04.029] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Revised: 03/31/2016] [Accepted: 04/09/2016] [Indexed: 10/21/2022]
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Keller EJ, Malaisrie SC, Kruse J, McCarthy PM, Carr JC, Markl M, Barker AJ, Collins JD. Reduction of aberrant aortic haemodynamics following aortic root replacement with a mechanical valved conduit. Interact Cardiovasc Thorac Surg 2016; 23:416-23. [PMID: 27245620 DOI: 10.1093/icvts/ivw173] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 04/20/2016] [Indexed: 11/12/2022] Open
Abstract
OBJECTIVES Previous work suggests that aortic root and valve prostheses alter blood flow patterns in the ascending aorta, creating aberrant haemodynamics compared with those of healthy volunteers. Various valve designs have been proposed to better restore physiological haemodynamics. In this study, magnetic resonance imaging (MRI) was used to non-invasively assess three-dimensional (3D) ascending aortic haemodynamics after aortic root replacement (ARR) with a mechanical valved conduit postulated to create less turbulent blood flow. METHODS Ten patients (40 ± 9 years) underwent transthoracic echocardiography and contrast-enhanced multidimensional four-dimensional (4D) flow MRI at 1.5 T after ARR with an On-X mechanical valved conduit. Preoperative 4D flow MRI was available in 7 patients. Ten age- and gender-matched healthy volunteers (42 ± 13 years) were also analysed to characterize physiological flow. The presence of vortex/helix formation was graded by two blinded observers. Peak transvalvular pressure gradients were computed using the simplified Bernoulli equation. Patients' postoperative pressure gradients and helicity/vorticity grades were compared with preoperative gradients and those from healthy volunteers. RESULTS Intra- and interobserver ratings showed good agreement (κ = 0.93, P < 0.01 and κ = 0.84, P < 0.01, respectively). Highly helical and/or vortical flow was observed in all patients preoperatively, which was significantly reduced postoperatively (P < 0.01 and <0.01, respectively), restoring similar flow patterns similar to those seen in volunteers (P = 0.56 and 0.56). Peak transvalvular pressure gradients (ΔP) were also significantly reduced [43 ± 21 vs 12 ± 7 mmHg, P < 0.05 (Echo); 48 ± 22 vs 16 ± 9 mmHg, P < 0.05 (MRI)], but remained significantly higher than those of volunteers (6 ± 1 mmHg, P < 0.01). CONCLUSIONS Preliminary evidence suggests that ARR with an On-X mechanical valve significantly reduces aberrant aortic haemodynamics, producing flow patterns that resemble those in healthy volunteers.
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Affiliation(s)
- Eric J Keller
- Department of Radiology, Northwestern University, Chicago, IL, USA
| | - S Chris Malaisrie
- Division of Surgery-Cardiac Surgery, Northwestern University, Chicago, IL, USA
| | - Jane Kruse
- Division of Surgery-Cardiac Surgery, Northwestern University, Chicago, IL, USA
| | - Patrick M McCarthy
- Division of Surgery-Cardiac Surgery, Northwestern University, Chicago, IL, USA
| | - James C Carr
- Department of Radiology, Northwestern University, Chicago, IL, USA
| | - Michael Markl
- Department of Radiology, Northwestern University, Chicago, IL, USA Department of Biomedical Engineeringy, Northwestern University, Evanston, IL, USA
| | - Alex J Barker
- Department of Radiology, Northwestern University, Chicago, IL, USA Department of Biomedical Engineeringy, Northwestern University, Evanston, IL, USA
| | - Jeremy D Collins
- Department of Radiology, Northwestern University, Chicago, IL, USA
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Lai CQ, Lim GL, Jamil M, Mattar CNZ, Biswas A, Yap CH. Fluid mechanics of blood flow in human fetal left ventricles based on patient-specific 4D ultrasound scans. Biomech Model Mechanobiol 2015; 15:1159-72. [DOI: 10.1007/s10237-015-0750-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2015] [Accepted: 12/01/2015] [Indexed: 11/28/2022]
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Collins JD, Semaan E, Barker A, McCarthy PM, Carr JC, Markl M, Malaisrie SC. Comparison of Hemodynamics After Aortic Root Replacement Using Valve-Sparing or Bioprosthetic Valved Conduit. Ann Thorac Surg 2015; 100:1556-62. [PMID: 26212514 PMCID: PMC4852688 DOI: 10.1016/j.athoracsur.2015.04.109] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Revised: 04/10/2015] [Accepted: 04/17/2015] [Indexed: 01/16/2023]
Abstract
BACKGROUND The purpose of this study is to compare aortic hemodynamics and blood flow patterns using in-vivo four-dimensional (4D) flow magnetic resonance imaging (MRI) in patients after valve-sparing aortic root replacement (VSARR) and aortic root replacement with bioprosthetic valves (BIO-ARR). METHODS In-vivo 4D flow MRI was performed in 11 patients after VSARR (47 ± 18 years, 6 bicuspid aortic valves, 5 trileaflet aortic valves), 16 patients after BIO-ARR (52 ± 14 years), and 10 healthy controls (47 ± 16 years). Analysis included three-dimensional blood flow visualization and grading of helix flow in the ascending aorta (AAo) and arch. Peak systolic velocity was quantified in 9 analysis planes in the AAo, aortic arch, and descending aorta. Flow profile uniformity was evaluated in the aortic root and ascending aorta. RESULTS Peak systolic velocity (2.0 to 2.5m/second) in the aortic root and AAo in both VSARR and BIO-ARR were elevated compared with controls (1.1 to 1.3m/second, p < 0.005). Flow asymmetry in BIO-ARR was increased compared with VSARR, evidenced by more AAo outflow jets (9 of 16 BIO-ARR, 0 of 11 in VSARR). The BIO-ARR exhibited significantly (p < 0.001) increased helix flow in the AAo as a measure of increased flow derangement. Finally, peak systolic velocities were elevated at the aortic root for BIO-ARR (2.5 vs 2.0m/second, p < 0.05) but lower in the distal AAo when compared with VSARR. CONCLUSIONS The VSARR results in improved hemodynamic outcomes when compared with BIO-ARR, as indicated by reduced peak velocities in the aortic root and less helix flow in the AAo by 4D flow MRI. Longitudinal research assessing the clinical impact of these differences in hemodynamic outcomes is warranted.
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Affiliation(s)
- Jeremy D Collins
- Department of Radiology, Northwestern University, Chicago, Illinois
| | - Edouard Semaan
- Department of Radiology, Northwestern University, Chicago, Illinois
| | - Alex Barker
- Department of Radiology, Northwestern University, Chicago, Illinois
| | - Patrick M McCarthy
- Division of Cardiac Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - James C Carr
- Department of Radiology, Northwestern University, Chicago, Illinois
| | - Michael Markl
- Department of Radiology, Northwestern University, Chicago, Illinois; Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University, Chicago, Illinois
| | - S Chris Malaisrie
- Division of Cardiac Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois.
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Kokkalis E, Aristokleous N, Houston JG. Haemodynamics and Flow Modification Stents for Peripheral Arterial Disease: A Review. Ann Biomed Eng 2015; 44:466-76. [PMID: 26467554 PMCID: PMC4764640 DOI: 10.1007/s10439-015-1483-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2015] [Accepted: 10/07/2015] [Indexed: 02/02/2023]
Abstract
Endovascular stents are widely used for the treatment of peripheral arterial disease (PAD). However, the development of in-stent restenosis and downstream PAD progression remain a challenge. Stent revascularisation of PAD causes arterial trauma and introduces abnormal haemodynamics, which initiate complicated biological processes detrimental to the arterial wall. The interaction between stent struts and arterial cells in contact, and the blood flow field created in a stented region, are highly affected by stent design. Spiral flow is known as a normal physiologic characteristic of arterial circulation and is believed to prevent the development of flow disturbances. This secondary flow motion is lost in atheromatous disease and its re-introduction after endovascular treatment of PAD has been suggested as a method to induce stabilised and coherent haemodynamics. Stent designs able to generate spiral flow may support endothelial function and therefore increase patency rates. This review is focused on secondary flow phenomena in arteries and the development of flow modification stent technologies for the treatment of PAD.
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Affiliation(s)
- Efstratios Kokkalis
- Division of Cardiovascular and Diabetes Medicine, Ninewells Hospital and Medical School, University of Dundee, Mail Box 1, Dundee, DD1 9SY, United Kingdom
| | - Nicolas Aristokleous
- Division of Cardiovascular and Diabetes Medicine, Ninewells Hospital and Medical School, University of Dundee, Mail Box 1, Dundee, DD1 9SY, United Kingdom.
| | - J Graeme Houston
- Division of Cardiovascular and Diabetes Medicine, Ninewells Hospital and Medical School, University of Dundee, Mail Box 1, Dundee, DD1 9SY, United Kingdom
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Dyverfeldt P, Bissell M, Barker AJ, Bolger AF, Carlhäll CJ, Ebbers T, Francios CJ, Frydrychowicz A, Geiger J, Giese D, Hope MD, Kilner PJ, Kozerke S, Myerson S, Neubauer S, Wieben O, Markl M. 4D flow cardiovascular magnetic resonance consensus statement. J Cardiovasc Magn Reson 2015; 17:72. [PMID: 26257141 PMCID: PMC4530492 DOI: 10.1186/s12968-015-0174-5] [Citation(s) in RCA: 548] [Impact Index Per Article: 60.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Accepted: 07/17/2015] [Indexed: 02/07/2023] Open
Abstract
Pulsatile blood flow through the cavities of the heart and great vessels is time-varying and multidirectional. Access to all regions, phases and directions of cardiovascular flows has formerly been limited. Four-dimensional (4D) flow cardiovascular magnetic resonance (CMR) has enabled more comprehensive access to such flows, with typical spatial resolution of 1.5×1.5×1.5 - 3×3×3 mm(3), typical temporal resolution of 30-40 ms, and acquisition times in the order of 5 to 25 min. This consensus paper is the work of physicists, physicians and biomedical engineers, active in the development and implementation of 4D Flow CMR, who have repeatedly met to share experience and ideas. The paper aims to assist understanding of acquisition and analysis methods, and their potential clinical applications with a focus on the heart and greater vessels. We describe that 4D Flow CMR can be clinically advantageous because placement of a single acquisition volume is straightforward and enables flow through any plane across it to be calculated retrospectively and with good accuracy. We also specify research and development goals that have yet to be satisfactorily achieved. Derived flow parameters, generally needing further development or validation for clinical use, include measurements of wall shear stress, pressure difference, turbulent kinetic energy, and intracardiac flow components. The dependence of measurement accuracy on acquisition parameters is considered, as are the uses of different visualization strategies for appropriate representation of time-varying multidirectional flow fields. Finally, we offer suggestions for more consistent, user-friendly implementation of 4D Flow CMR acquisition and data handling with a view to multicenter studies and more widespread adoption of the approach in routine clinical investigations.
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Affiliation(s)
- Petter Dyverfeldt
- Division of Cardiovascular Medicine, Department of Medical and Health Sciences, Linköping University, Linköping, Sweden.
- Center for Medical Image Science and Visualization, Linköping University, Linköping, Sweden.
| | - Malenka Bissell
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford Centre for Clinical Magnetic Resonance Research, Oxford, UK.
| | - Alex J Barker
- Department of Radiology, Northwestern University, Chicago, USA.
| | - Ann F Bolger
- Division of Cardiovascular Medicine, Department of Medical and Health Sciences, Linköping University, Linköping, Sweden.
- Center for Medical Image Science and Visualization, Linköping University, Linköping, Sweden.
- Department of Medicine, University of California San Francisco, San Francisco, CA, United States.
| | - Carl-Johan Carlhäll
- Division of Cardiovascular Medicine, Department of Medical and Health Sciences, Linköping University, Linköping, Sweden.
- Center for Medical Image Science and Visualization, Linköping University, Linköping, Sweden.
- Department of Clinical Physiology, Department of Medical and Health Sciences, Linköping University, Linköping, Sweden.
| | - Tino Ebbers
- Division of Cardiovascular Medicine, Department of Medical and Health Sciences, Linköping University, Linköping, Sweden.
- Center for Medical Image Science and Visualization, Linköping University, Linköping, Sweden.
| | | | - Alex Frydrychowicz
- Klinik für Radiologie und Nuklearmedizin, University Hospital Schleswig-Holstein, Campus Lübeck, Lübeck, Germany.
| | - Julia Geiger
- Department of Radiology, University Children's Hospital Zurich, Zurich, Switzerland.
| | - Daniel Giese
- Department of Radiology, University Hospital of Cologne, Cologne, Germany.
| | - Michael D Hope
- Department of Radiology, University of California San Francisco, San Francisco, CA, United States.
| | - Philip J Kilner
- NIHR Cardiovascular Biomedical Research Unit, Royal Brompton and Harefield NHS Foundation Trust, National Heart and Lung Institute, Imperial College, London, UK.
| | - Sebastian Kozerke
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland.
| | - Saul Myerson
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford Centre for Clinical Magnetic Resonance Research, Oxford, UK.
| | - Stefan Neubauer
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford Centre for Clinical Magnetic Resonance Research, Oxford, UK.
| | - Oliver Wieben
- Department of Radiology, University of Wisconsin, Madison, Wisconsin, USA.
- Department of Medical Physics, University of Wisconsin, Madison, Wisconsin, USA.
| | - Michael Markl
- Department of Radiology, Northwestern University, Chicago, USA.
- Department of Biomedical Engineering, Northwestern University, Chicago, IL, USA.
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Kokkalis E, Cookson AN, Stonebridge PA, Corner GA, Houston JG, Hoskins PR. Comparison of vortical structures induced by arteriovenous grafts using vector Doppler ultrasound. ULTRASOUND IN MEDICINE & BIOLOGY 2015; 41:760-774. [PMID: 25683221 DOI: 10.1016/j.ultrasmedbio.2014.10.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Revised: 08/18/2014] [Accepted: 10/18/2014] [Indexed: 06/04/2023]
Abstract
Arteriovenous prosthetic grafts are used in hemodialysis. Stenosis in the venous anastomosis is the main cause of occlusion and the role of local hemodynamics in this is considered significant. A new spiral graft design has been proposed to stabilize the flow phenomena in the host vein. Cross-flow vortical structures in the outflow of this graft were compared with those from a control device. Both grafts were integrated in identical in-house ultrasound-compatible flow phantoms with realistic surgical configurations. Constant flow rates were applied. In-plane 2-D velocity and vorticity mapping was developed using a vector Doppler technique. One or two vortices were detected for the spiral graft and two to four for the control, along with reduced stagnation points for the former. The in-plane peak velocity and circulation were calculated and found to be greater for the spiral device, implying increased in-plane mixing, which is believed to inhibit thrombosis and neo-intimal hyperplasia.
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Affiliation(s)
- Efstratios Kokkalis
- Institute for Medical Science and Technology, University of Dundee, Dundee, UK; Cardiovascular and Diabetes Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee, UK.
| | - Andrew N Cookson
- Department of Biomedical Engineering, King's College London, London, UK
| | - Peter A Stonebridge
- Cardiovascular and Diabetes Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee, UK
| | - George A Corner
- Medical Physics, Ninewells Hospital and Medical School, Dundee, UK
| | - J Graeme Houston
- Cardiovascular and Diabetes Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee, UK
| | - Peter R Hoskins
- Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK
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Abstract
4D flow MRI permits a comprehensive in-vivo assessment of three-directional blood flow within 3-dimensional vascular structures throughout the cardiac cycle. Given the large coverage permitted from a 4D flow acquisition, the distribution of vessel wall and flow parameters along an entire vessel of interest can thus be derived from a single measurement without being dependent on multiple predefined 2D acquisitions. In addition to qualitative 3D visualizations of complex cardiac and vascular flow patterns, quantitative flow analysis can be performed and is complemented by the ability to compute sophisticated hemodynamic parameters, such as wall shear stress or 3D pressure difference maps. These metrics can provide information previously unavailable with conventional modalities regarding the impact of cardiovascular disease or therapy on global and regional changes in hemodynamics. This review provides an introduction to the methodological aspects of 4D flow MRI to assess vascular hemodynamics and describes its potential for the assessment and understanding of altered hemodynamics in the presence of cardiovascular disease.
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50
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Velocity mapping of the aortic flow at 9.4 T in healthy mice and mice with induced heart failure using time-resolved three-dimensional phase-contrast MRI (4D PC MRI). MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2014; 28:315-27. [PMID: 25381179 PMCID: PMC4515240 DOI: 10.1007/s10334-014-0466-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Revised: 09/23/2014] [Accepted: 10/14/2014] [Indexed: 11/28/2022]
Abstract
Objectives In this study, we established and validated a time-resolved three-dimensional phase-contrast magnetic resonance imaging method (4D PC MRI) on a 9.4 T small-animal MRI system. Herein we present the feasibility of 4D PC MRI in terms of qualitative and quantitative flow pattern analysis in mice with transverse aortic constriction (TAC). Materials and methods 4D PC FLASH images of a flow phantom and mouse heart were acquired at 9.4 T using a four-point phase-encoding scheme. The method was compared with slice-selective PC FLASH and ultrasound using Bland–Altman analysis. Advanced 3D streamlines were visualized utilizing Voreen volume-rendering software. Results In vitro, 4D PC MRI flow profiles showed the transition between laminar and turbulent flow with increasing velocities. In vivo, 4D PC MRI data of the ascending aorta and the pulmonary artery were confirmed by ultrasound, resulting in linear regressions of R2 > 0.93. Magnitude- and direction-encoded streamlines differed substantially pre- and post-TAC surgery. Conclusions 4D PC MRI is a feasible tool for in vivo velocity measurements on high-field small-animal scanners. Similar to clinical measurement, this method provides a complete spatially and temporally resolved dataset of the murine cardiovascular blood flow and allows for three-dimensional flow pattern analysis. Electronic supplementary material The online version of this article (doi:10.1007/s10334-014-0466-z) contains supplementary material, which is available to authorized users.
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