1
|
Curry BA, Drane AL, Atencia R, Feltrer Y, Calvi T, Milnes EL, Moittié S, Weigold A, Knauf-Witzens T, Sawung Kusuma A, Howatson G, Palmer C, Stembridge MR, Gorzynski JE, Eves ND, Dawkins TG, Shave RE. Left ventricular trabeculation in Hominidae: divergence of the human cardiac phenotype. Commun Biol 2024; 7:682. [PMID: 38877299 PMCID: PMC11178792 DOI: 10.1038/s42003-024-06280-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Accepted: 05/02/2024] [Indexed: 06/16/2024] Open
Abstract
Although the gross morphology of the heart is conserved across mammals, subtle interspecific variations exist in the cardiac phenotype, which may reflect evolutionary divergence among closely-related species. Here, we compare the left ventricle (LV) across all extant members of the Hominidae taxon, using 2D echocardiography, to gain insight into the evolution of the human heart. We present compelling evidence that the human LV has diverged away from a more trabeculated phenotype present in all other great apes, towards a ventricular wall with proportionally greater compact myocardium, which was corroborated by post-mortem chimpanzee (Pan troglodytes) hearts. Speckle-tracking echocardiographic analyses identified a negative curvilinear relationship between the degree of trabeculation and LV systolic twist, revealing lower rotational mechanics in the trabeculated non-human great ape LV. This divergent evolution of the human heart may have facilitated the augmentation of cardiac output to support the metabolic and thermoregulatory demands of the human ecological niche.
Collapse
Affiliation(s)
- Bryony A Curry
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, BC, V1V 1V7, Canada
| | - Aimee L Drane
- International Primate Heart Project, Cardiff Metropolitan University, Cyncoed Road, Cardiff, CF23 6XD, UK.
- Faculty of Medicine, Health and Life Sciences, Swansea University, Swansea, SA2 8PP, UK.
| | - Rebeca Atencia
- Jane Goodall Institute, Tchimpounga Chimpanzee Rehabilitation Centre, Pointe-Noire, Republic of Congo
| | - Yedra Feltrer
- International Primate Heart Project, Cardiff Metropolitan University, Cyncoed Road, Cardiff, CF23 6XD, UK
| | - Thalita Calvi
- Chimfunshi Wildlife Orphanage, Solwesi Road, Chingola, Zambia
| | - Ellie L Milnes
- Wildlife Health, Pathobiology and Population Sciences, Royal Veterinary College, University of London, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire, AL9 7TA, UK
- Zoological Society of London, Regent's Park, London, NW1 4RY, UK
- Centre for Veterinary Wildlife Research, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort, Pretoria, 0110, South Africa
| | - Sophie Moittié
- Tacugama Chimpanzee Sanctuary, Congo Dam Access Road, Freetown, Sierra Leone
- School of Veterinary Medicine, St. George's University, St. George's, West Indies, Grenada
| | - Annika Weigold
- Wilhelma Zoological-Botanical Gardens, Wilhelma 13, Stuttgart, 70376, Germany
| | | | - Arga Sawung Kusuma
- Borneo Orangutan Survival Foundation, Central Kalimantan Orangutan Reintroduction Project at Nyaru Menteng, Jalan Cilik Riwut km 28, Palangkaraya, 73111, Central Kalimantan, Indonesia
| | - Glyn Howatson
- Faculty of Health and Life Sciences, Northumbria University, Newcastle-upon-Tyne, NE1 8ST, UK
- Water Research Group, Faculty of Natural and Environmental Sciences, North West University, Potchefstroom, 2531, South Africa
| | - Christopher Palmer
- Biological Science, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Mike R Stembridge
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, CF23 6XD, UK
| | - John E Gorzynski
- Department of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Neil D Eves
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, BC, V1V 1V7, Canada
| | - Tony G Dawkins
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, BC, V1V 1V7, Canada
| | - Rob E Shave
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, BC, V1V 1V7, Canada.
| |
Collapse
|
2
|
Yuan N, Wang L, Ye C, Deng Z, Zhang J, Zhu Y. Self-supervised structural similarity-based convolutional neural network for cardiac diffusion tensor image denoising. Med Phys 2023; 50:6137-6150. [PMID: 36775901 DOI: 10.1002/mp.16301] [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: 08/16/2022] [Revised: 12/12/2022] [Accepted: 01/03/2023] [Indexed: 02/14/2023] Open
Abstract
BACKGROUND Diffusion tensor imaging (DTI) is a promising technique for non-invasively investigating the myocardial fiber structures of human heart. However, low signal-to-noise ratio (SNR) has been a major limit of cardiac DTI to prevent us from detecting myocardium structure accurately. Therefore, it is important to remove the effect of noise on diffusion weighted (DW) images. PURPOSE Although the conventional and deep learning-based denoising methods have shown the potential to deal with effectively the noise in DW images, most of them are redundant information dependent or require the noise-free images as golden standard. In addition, the existed DW image denoising methods often suffer from problems of over-smoothing. To address these issues, we propose a self-supervised learning model, structural similarity based convolutional neural network with edge-weighted loss (SSECNN), to remove the noise effectively in cardiac DTI. METHODS Considering that the DW images acquired along different diffusion directions have structural similarity, and the noise in these DW images is independent and identically distributed, the structural similarity-based matching algorithm is proposed to search for the most similar DW images. Such similar noisy DW image pairs are then used as the input and target of the denoising network SSECNN, which consists of several convolutional and residual blocks. Through the self-supervised training with these image pairs, the network can restore the clean DW images and retain the correlations between the denoised DW images along different directions. To avoid the over-smoothing problem, we design a novel edge-weighted loss which enables the network to adaptively adjust the loss weights with iterations and therefore to improve the detail preserve ability of the model. To verify the superiority of the proposed method, comparisons with state-of-the-art (SOTA) denoising methods are performed on both synthetic and real acquired DTI datasets. RESULTS Experimental results show that SSECNN can effectively reduce the noise in the DW images while preserving detailed texture and edge information and therefore achieve better performance in DTI reconstruction. For synthetic dataset, compared to the SOTA method, the root mean square error (RMSE), peak signal-to-noise ratio (PSNR), and structure similarity index measure (SSIM) between the denoised DW images obtained with SSECNN and noise-free DW images are improved by 6.94%, 1.98%, and 0.76% respectively when the noise level is 10%. As for the acquired cardiac DTI dataset, the SSECNN method could significantly improve SNR and contrast to noise ratio (CNR) of cardiac DW images and achieve more regular helix angle (HA) and transverse angle (TA) maps. The ablation experimental results validate that using the structure similarity-based method to search the similar DW image pairs yield the smallest loss, and with the help of the edge-weighted loss, the denoised DW images and diffusion metric maps can preserve more details. CONCLUSIONS The proposed SSECNN method can fully explore the similarity between the DW images along different diffusion directions. Using such similarity and an edge-weighted loss enable us to denoise cardiac DTI effectively in a self-supervised manner. Our method can overcome the redundancy information dependence and over-smoothing problem of the SOTA methods.
Collapse
Affiliation(s)
- Nannan Yuan
- Key Laboratory of Intelligent Medical Image Analysis and Precise Diagnosis of Guizhou Province, State Key Laboratory of Public Big Data, College of Computer Science and Technology, Guizhou University, Guiyang, China
| | - Lihui Wang
- Key Laboratory of Intelligent Medical Image Analysis and Precise Diagnosis of Guizhou Province, State Key Laboratory of Public Big Data, College of Computer Science and Technology, Guizhou University, Guiyang, China
| | - Chen Ye
- Key Laboratory of Intelligent Medical Image Analysis and Precise Diagnosis of Guizhou Province, State Key Laboratory of Public Big Data, College of Computer Science and Technology, Guizhou University, Guiyang, China
| | - Zeyu Deng
- Key Laboratory of Intelligent Medical Image Analysis and Precise Diagnosis of Guizhou Province, State Key Laboratory of Public Big Data, College of Computer Science and Technology, Guizhou University, Guiyang, China
| | - Jian Zhang
- Key Laboratory of Intelligent Medical Image Analysis and Precise Diagnosis of Guizhou Province, State Key Laboratory of Public Big Data, College of Computer Science and Technology, Guizhou University, Guiyang, China
| | - Yuemin Zhu
- Univ Lyon, INSA Lyon, CNRS, Inserm, CREATIS UMR 5220, U1206, Lyon, France
| |
Collapse
|
3
|
Eder RA, van den Boomen M, Yurista SR, Rodriguez-Aviles YG, Islam MR, Chen YCI, Trager L, Coll-Font J, Cheng L, Li H, Rosenzweig A, Wrann CD, Nguyen CT. Exercise-induced CITED4 expression is necessary for regional remodeling of cardiac microstructural tissue helicity. Commun Biol 2022; 5:656. [PMID: 35787681 PMCID: PMC9253017 DOI: 10.1038/s42003-022-03635-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 06/23/2022] [Indexed: 11/10/2022] Open
Abstract
Both exercise-induced molecular mechanisms and physiological cardiac remodeling have been previously studied on a whole heart level. However, the regional microstructural tissue effects of these molecular mechanisms in the heart have yet to be spatially linked and further elucidated. We show in exercised mice that the expression of CITED4, a transcriptional co-regulator necessary for cardioprotection, is regionally heterogenous in the heart with preferential significant increases in the lateral wall compared with sedentary mice. Concordantly in this same region, the heart's local microstructural tissue helicity is also selectively increased in exercised mice. Quantification of CITED4 expression and microstructural tissue helicity reveals a significant correlation across both sedentary and exercise mouse cohorts. Furthermore, genetic deletion of CITED4 in the heart prohibits regional exercise-induced microstructural helicity remodeling. Taken together, CITED4 expression is necessary for exercise-induced regional remodeling of the heart's microstructural helicity revealing how a key molecular regulator of cardiac remodeling manifests into downstream local tissue-level changes.
Collapse
Affiliation(s)
- Robert A Eder
- Cardiovascular Research Center, Massachusetts General Hospital, Charlestown, MA, 02129, USA
| | - Maaike van den Boomen
- Cardiovascular Research Center, Massachusetts General Hospital, Charlestown, MA, 02129, USA
- Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, 02129, USA
- Department of Radiology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands
- Harvard Medical School, Boston, MA, 02129, USA
| | - Salva R Yurista
- Cardiovascular Research Center, Massachusetts General Hospital, Charlestown, MA, 02129, USA
- Harvard Medical School, Boston, MA, 02129, USA
| | - Yaiel G Rodriguez-Aviles
- Cardiovascular Research Center, Massachusetts General Hospital, Charlestown, MA, 02129, USA
- Ponce Health Sciences University, School of Medicine, Ponce, PR, 00716, USA
| | - Mohammad Rashedul Islam
- Cardiovascular Research Center, Massachusetts General Hospital, Charlestown, MA, 02129, USA
- Harvard Medical School, Boston, MA, 02129, USA
| | - Yin-Ching Iris Chen
- Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, 02129, USA
- Harvard Medical School, Boston, MA, 02129, USA
| | - Lena Trager
- Cardiovascular Research Center, Massachusetts General Hospital, Charlestown, MA, 02129, USA
| | - Jaume Coll-Font
- Cardiovascular Research Center, Massachusetts General Hospital, Charlestown, MA, 02129, USA
- Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, 02129, USA
- Harvard Medical School, Boston, MA, 02129, USA
| | - Leo Cheng
- Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, 02129, USA
- Harvard Medical School, Boston, MA, 02129, USA
| | - Haobo Li
- Cardiovascular Research Center, Massachusetts General Hospital, Charlestown, MA, 02129, USA
- Harvard Medical School, Boston, MA, 02129, USA
| | - Anthony Rosenzweig
- Cardiovascular Research Center, Massachusetts General Hospital, Charlestown, MA, 02129, USA
- Harvard Medical School, Boston, MA, 02129, USA
- Massachusetts General Hospital, Cardiology Division and Corrigan Minehan Heart Center, Boston, MA, 02114, USA
| | - Christiane D Wrann
- Cardiovascular Research Center, Massachusetts General Hospital, Charlestown, MA, 02129, USA.
- Harvard Medical School, Boston, MA, 02129, USA.
- McCance Center for Brain Health, Massachusetts General Hospital, Boston, MA, 02114, USA.
| | - Christopher T Nguyen
- Cardiovascular Research Center, Massachusetts General Hospital, Charlestown, MA, 02129, USA.
- Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, 02129, USA.
- Harvard Medical School, Boston, MA, 02129, USA.
- Division of Health Sciences and Technology, Harvard-Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
- Cardiovascular Innovation Research Center, Heart, Vascular, and Thoracic Institute, Cleveland Clinic, Cleveland, Ohio, 44195, USA.
| |
Collapse
|
4
|
Stimm J, Buoso S, Berberoğlu E, Kozerke S, Genet M, Stoeck CT. A 3D personalized cardiac myocyte aggregate orientation model using MRI data-driven low-rank basis functions. Med Image Anal 2021; 71:102064. [PMID: 33957560 DOI: 10.1016/j.media.2021.102064] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 03/01/2021] [Accepted: 03/31/2021] [Indexed: 12/17/2022]
Abstract
Cardiac myocyte aggregate orientation has a strong impact on cardiac electrophysiology and mechanics. Studying the link between structural characteristics, strain, and stresses over the cardiac cycle and cardiac function requires a full volumetric representation of the microstructure. In this work, we exploit the structural similarity across hearts to extract a low-rank representation of predominant myocyte orientation in the left ventricle from high-resolution magnetic resonance ex-vivo cardiac diffusion tensor imaging (cDTI) in porcine hearts. We compared two reduction methods, Proper Generalized Decomposition combined with Singular Value Decomposition and Proper Orthogonal Decomposition. We demonstrate the existence of a general set of basis functions of aggregated myocyte orientation which defines a data-driven, personalizable, parametric model featuring higher flexibility than existing atlas and rule-based approaches. A more detailed representation of microstructure matching the available patient data can improve the accuracy of personalized computational models. Additionally, we approximate the myocyte orientation of one ex-vivo human heart and demonstrate the feasibility of transferring the basis functions to humans.
Collapse
Affiliation(s)
- Johanna Stimm
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
| | - Stefano Buoso
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
| | - Ezgi Berberoğlu
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
| | - Sebastian Kozerke
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
| | - Martin Genet
- Laboratoire de Mécanique des Solides, École Polytechnique, Palaiseau, France; M3DISIM team, Inria / Université Paris-Saclay, Palaiseau, France; C.N.R.S./Université Paris-Saclay, Palaiseau, France
| | - Christian T Stoeck
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland.
| |
Collapse
|
5
|
Kakaletsis S, Meador WD, Mathur M, Sugerman GP, Jazwiec T, Malinowski M, Lejeune E, Timek TA, Rausch MK. Right ventricular myocardial mechanics: Multi-modal deformation, microstructure, modeling, and comparison to the left ventricle. Acta Biomater 2021; 123:154-166. [PMID: 33338654 PMCID: PMC7946450 DOI: 10.1016/j.actbio.2020.12.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Revised: 11/30/2020] [Accepted: 12/02/2020] [Indexed: 01/03/2023]
Abstract
The right ventricular myocardium, much like the rest of the right side of the heart, has been consistently understudied. Presently, little is known about its mechanics, its microstructure, and its constitutive behavior. In this work, we set out to provide the first data on the mechanics of the mature right ventricular myocardium in both simple shear and uniaxial loading and to compare these data to the mechanics of the left ventricular myocardium. To this end, we tested ovine tissue samples of the right and left ventricle under a comprehensive mechanical testing protocol that consisted of six simple shear modes and three tension/compression modes. After mechanical testing, we conducted a histology-based microstructural analysis on each right ventricular sample that yielded high resolution fiber distribution maps across the entire samples. Equipped with this detailed mechanical and histological data, we employed an inverse finite element framework to determine the optimal form and parameters for microstructure-based constitutive models. The results of our study show that right ventricular myocardium is less stiff then the left ventricular myocardium in the fiber direction, but similarly exhibits non-linear, anisotropic, and tension/compression asymmetric behavior with direction-dependent Poynting effect. In addition, we found that right ventricular myocardial fibers change angles transmurally and are dispersed within the sheet plane and normal to it. Through our inverse finite element analysis, we found that the Holzapfel model successfully fits these data, even when selectively informed by rudimentary microstructural information. And, we found that the inclusion of higher-fidelity microstructural data improved the Holzapfel model's predictive ability. Looking forward, this investigation is a critical step towards understanding the fundamental mechanical behavior of right ventricular myocardium and lays the groundwork for future whole-organ mechanical simulations.
Collapse
Affiliation(s)
- Sotirios Kakaletsis
- Department of Aerospace Engineering and Engineering Mechanics, The University of Texas at Austin, Austin, TX 78712, USA
| | - William D Meador
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712, USA
| | - Mrudang Mathur
- Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Gabriella P Sugerman
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712, USA
| | - Tomasz Jazwiec
- Cardiothoracic Surgery, Spectrum Health, Grand Rapids, MI, 49503, USA; Department of Cardiac, Vascular, and Endovascular Surgery and Transplantology, Medical University of Silesia School of Medicine in Katowice, Silesian Centre for Heart Diseases, Zabrze, Poland
| | - Marcin Malinowski
- Cardiothoracic Surgery, Spectrum Health, Grand Rapids, MI, 49503, USA; Department of Cardiac Surgery, Medical University of Silesia School of Medicine in Katowice, Katowice, Poland
| | - Emma Lejeune
- Department of Mechanical Engineering, Boston University, Boston, MA, 02215, USA
| | - Tomasz A Timek
- Cardiothoracic Surgery, Spectrum Health, Grand Rapids, MI, 49503, USA
| | - Manuel K Rausch
- Department of Aerospace Engineering and Engineering Mechanics, The University of Texas at Austin, Austin, TX 78712, USA; Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712, USA; Oden Institute for Computational Engineering and Sciences, The University of Texas at Austin, Austin, TX, 78712, USA.
| |
Collapse
|
6
|
3D MRI of explanted sheep hearts with submillimeter isotropic spatial resolution: comparison between diffusion tensor and structure tensor imaging. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2021; 34:741-755. [PMID: 33638739 PMCID: PMC8421292 DOI: 10.1007/s10334-021-00913-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 01/29/2021] [Accepted: 02/02/2021] [Indexed: 11/04/2022]
Abstract
Objective The aim of the study is to compare structure tensor imaging (STI) with diffusion tensor imaging (DTI) of the sheep heart (approximately the same size as the human heart). Materials and methods MRI acquisition on three sheep ex vivo hearts was performed at 9.4 T/30 cm with a seven-element RF coil. 3D FLASH with an isotropic resolution of 150 µm and 3D spin-echo DTI at 600 µm were performed. Tensor analysis, angles extraction and segments divisions were performed on both volumes. Results A 3D FLASH allows for visualization of the detailed structure of the left and right ventricles. The helix angle determined using DTI and STI exhibited a smooth transmural change from the endocardium to the epicardium. Both the helix and transverse angles were similar between techniques. Sheetlet organization exhibited the same pattern in both acquisitions, but local angle differences were seen and identified in 17 segments representation. Discussion This study demonstrated the feasibility of high-resolution MRI for studying the myocyte and myolaminar architecture of sheep hearts. We presented the results of STI on three whole sheep ex vivo hearts and demonstrated a good correspondence between DTI and STI. Supplementary Information The online version contains supplementary material available at 10.1007/s10334-021-00913-4.
Collapse
|
7
|
Sharifi Kia D, Fortunato R, Maiti S, Simon MA, Kim K. An exploratory assessment of stretch-induced transmural myocardial fiber kinematics in right ventricular pressure overload. Sci Rep 2021; 11:3587. [PMID: 33574400 PMCID: PMC7878470 DOI: 10.1038/s41598-021-83154-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 01/22/2021] [Indexed: 01/30/2023] Open
Abstract
Right ventricular (RV) remodeling and longitudinal fiber reorientation in the setting of pulmonary hypertension (PH) affects ventricular structure and function, eventually leading to RV failure. Characterizing the kinematics of myocardial fibers helps better understanding the underlying mechanisms of fiber realignment in PH. In the current work, high-frequency ultrasound imaging and structurally-informed finite element (FE) models were employed for an exploratory evaluation of the stretch-induced kinematics of RV fibers. Image-based experimental evaluation of fiber kinematics in porcine myocardium revealed the capability of affine assumptions to effectively approximate myofiber realignment in the RV free wall. The developed imaging framework provides a noninvasive modality to quantify transmural RV myofiber kinematics in large animal models. FE modeling results demonstrated that chronic pressure overload, but not solely an acute rise in pressures, results in kinematic shift of RV fibers towards the longitudinal direction. Additionally, FE simulations suggest a potential protective role for concentric hypertrophy (increased wall thickness) against fiber reorientation, while eccentric hypertrophy (RV dilation) resulted in longitudinal fiber realignment. Our study improves the current understanding of the role of different remodeling events involved in transmural myofiber reorientation in PH. Future experimentations are warranted to test the model-generated hypotheses.
Collapse
Affiliation(s)
- Danial Sharifi Kia
- grid.21925.3d0000 0004 1936 9000Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA USA
| | - Ronald Fortunato
- grid.21925.3d0000 0004 1936 9000Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, PA USA
| | - Spandan Maiti
- grid.21925.3d0000 0004 1936 9000Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA USA ,grid.21925.3d0000 0004 1936 9000Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, PA USA
| | - Marc A. Simon
- grid.21925.3d0000 0004 1936 9000Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA USA ,grid.21925.3d0000 0004 1936 9000Division of Cardiology, Department of Medicine, University of Pittsburgh School of Medicine, 623A Scaife Hall, 3550 Terrace Street, Pittsburgh, PA 15213 USA ,grid.412689.00000 0001 0650 7433Heart and Vascular Institute, University of Pittsburgh Medical Center (UPMC), Pittsburgh, PA USA ,grid.412689.00000 0001 0650 7433Pittsburgh Heart, Lung, Blood and Vascular Medicine Institute, University of Pittsburgh and University of Pittsburgh Medical Center (UPMC), Pittsburgh, PA USA ,grid.21925.3d0000 0004 1936 9000McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA USA
| | - Kang Kim
- grid.21925.3d0000 0004 1936 9000Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA USA ,grid.21925.3d0000 0004 1936 9000Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, PA USA ,grid.21925.3d0000 0004 1936 9000Division of Cardiology, Department of Medicine, University of Pittsburgh School of Medicine, 623A Scaife Hall, 3550 Terrace Street, Pittsburgh, PA 15213 USA ,grid.412689.00000 0001 0650 7433Heart and Vascular Institute, University of Pittsburgh Medical Center (UPMC), Pittsburgh, PA USA ,grid.412689.00000 0001 0650 7433Pittsburgh Heart, Lung, Blood and Vascular Medicine Institute, University of Pittsburgh and University of Pittsburgh Medical Center (UPMC), Pittsburgh, PA USA ,grid.21925.3d0000 0004 1936 9000McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA USA ,grid.21925.3d0000 0004 1936 9000Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh, Pittsburgh, PA USA
| |
Collapse
|
8
|
Agger P, Stephenson RS. Assessing Myocardial Architecture: The Challenges and Controversies. J Cardiovasc Dev Dis 2020; 7:jcdd7040047. [PMID: 33137874 PMCID: PMC7711767 DOI: 10.3390/jcdd7040047] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 10/04/2020] [Accepted: 10/08/2020] [Indexed: 12/16/2022] Open
Abstract
In recent decades, investigators have strived to describe and quantify the orientation of the cardiac myocytes in an attempt to classify their arrangement in healthy and diseased hearts. There are, however, striking differences between the investigations from both a technical and methodological standpoint, thus limiting their comparability and impeding the drawing of appropriate physiological conclusions from the structural assessments. This review aims to elucidate these differences, and to propose guidance to establish methodological consensus in the field. The review outlines the theory behind myocyte orientation analysis, and importantly has identified pronounced differences in the definitions of otherwise widely accepted concepts of myocytic orientation. Based on the findings, recommendations are made for the future design of studies in the field of myocardial morphology. It is emphasised that projection of myocyte orientations, before quantification of their angulation, introduces considerable bias, and that angles should be assessed relative to the epicardial curvature. The transmural orientation of the cardiomyocytes should also not be neglected, as it is an important determinant of cardiac function. Finally, there is considerable disagreement in the literature as to how the orientation of myocardial aggregates should be assessed, but to do so in a mathematically meaningful way, the normal vector of the aggregate plane should be utilised.
Collapse
Affiliation(s)
- Peter Agger
- Comparative Medicine Lab, Department of Clinical Medicine, Aarhus University, 8220 Aarhus N, Denmark
- Department of Pediatrics, Randers Regional Hospital, Skovlyvej 15, 8930 Randers NE, Denmark
- Correspondence:
| | - Robert S. Stephenson
- Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, UK;
| |
Collapse
|
9
|
Giannakidis A, Gullberg GT. Transmural Remodeling of Cardiac Microstructure in Aged Spontaneously Hypertensive Rats by Diffusion Tensor MRI. Front Physiol 2020; 11:265. [PMID: 32296341 PMCID: PMC7136532 DOI: 10.3389/fphys.2020.00265] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 03/09/2020] [Indexed: 11/16/2022] Open
Abstract
The long-standing high blood pressure (also known as hypertension) overworks the heart. Microstructural remodeling is a key factor of hypertensive heart disease progression. Diffusion tensor magnetic resonance imaging (DT-MRI) is a powerful tool for the rapid noninvasive nondestructive delineation of the cardiomyocyte organization. The spontaneously hypertensive rat (SHR) is a well-established model of genetic hypertension. The goal of this study was to employ high-resolution DT-MRI and the SHR animal model to assess the transmural layer-specific remodeling of myocardial microstructure associated with hypertension. Ex vivo experiments were performed on excised formalin-fixed hearts of aged SHRs (n = 4) and age-matched controls (n = 4). The DT-MRI-derived fractional anisotropy (FA), longitudinal diffusivity (λL), transversal diffusivity (λT), and mean diffusivity (MD) served as the readout parameters investigated at three transmural zones (i.e., endocardium, mesocardium, and epicardium). The helix angles (HAs) of the aggregated cardiomyocytes and the orientation of laminar sheetlets were also studied. Compared with controls, the SHRs exhibited decreased epicardial FA, while FA changes in the other two transmural regions were insignificant. No substantial differences were observed in the diffusivity parameters and the transmural course of HAs between the two groups. A consistent distribution pattern of laminar sheetlet orientation was not identified for either group. Our findings are in line with the known cellular microstructure from early painstaking histological studies. Biophysical explanations of the study outcomes are provided. In conclusion, our experimental findings indicate that the epicardial microstructure is more vulnerable to high blood pressure leading to more pronounced changes in this region during remodeling. DT-MRI is well-suited for elucidating these alterations. The revealed transmural nonuniformity of myocardial reorganization may shed light on the mechanisms of the microstructure-function relationship in hypertension progression. Our results provide insights into the management of patients with systemic arterial hypertension, thus prevent the progression toward heart failure. The findings of this study should be acknowledged by electromechanical models of the heart that simulate the specific cardiac pathology.
Collapse
Affiliation(s)
- Archontis Giannakidis
- School of Science and Technology, Nottingham Trent University, Nottingham, United Kingdom.,Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States.,National Heart & Lung Institute, Imperial College London, London, United Kingdom
| | - Grant T Gullberg
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States.,Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, United States
| |
Collapse
|
10
|
Agger P, Omann C, Laustsen C, Stephenson RS, Anderson RH. Anatomically correct assessment of the orientation of the cardiomyocytes using diffusion tensor imaging. NMR IN BIOMEDICINE 2020; 33:e4205. [PMID: 31829484 DOI: 10.1002/nbm.4205] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 10/04/2019] [Accepted: 10/07/2019] [Indexed: 06/10/2023]
Abstract
Diffusion tensor imaging has been used for assessing the orientation of cardiac myocytes for decades. Striking methodological differences exist between studies when quantifying these orientations. This limits the comparability between studies, and impedes collaboration and the drawing of appropriate physiological conclusions. We have sought to elucidate these differences, permitting us to propose a standardised "tool set" that might better establish consensus in future studies. We fixed hearts from seven 25 kg pigs in formalin, and scanned them using diffusion tensor imaging. Using various angle definitions as found in literature, we assessed the orientations of cardiomyocytes, comparing them in terms of helical and intrusion angles, along with the orientation of their aggregations. The difference between assessment of the helical angle with and without relation to the epicardial curvature was 25.2° (SD: 7.9) at the base, 5.8° (1.9) at the equatorial level, and 28.0° (7.0) at the apex, ANOVA P = 0.001. In comparable fashion, the intrusion angle differed by 25.9° (12.9), 7.6° (0.98) and 17.5° (4.7), P = 0.01, and the angle of the aggregates (E3-angle) differed by 25.0° (13.5) at the base, 9.4° (1.7) at the equator, and 23.1° (6.2) apically, P = 0.003. When assessing 14 definitions used in literature to calculate the orientation of aggregates, only 4 rendered identical results. The findings show that any attempt to use projection of eigenvectors introduces considerable bias. The epicardial curvature of the ventricular cone needs to be taken into account when seeking to provide accurate quantification of the orientation of the aggregated cardiomyocytes, especially in the apical and basal regions. This means that projection of eigenvectors should be avoided prior to quantifying myocyte orientation, especially when assessing radial orientation. Based on our results, we suggest appropriate methods for valid assessment of myocyte orientation using diffusion tensor imaging.
Collapse
Affiliation(s)
- Peter Agger
- Comparative Medicine Lab, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Camilla Omann
- Dept. of Cardiothoracic & Vascular Surgery, Aarhus University Hospital, Aarhus, Denmark
| | | | - Robert S Stephenson
- Comparative Medicine Lab, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
- Institute of Clinical Sciences, The University of Birmingham, Birmingham, UK
| | - Robert H Anderson
- Institute Genetic Medicine, Newcastle University, Newcastle-upon-Tyne, UK
| |
Collapse
|
11
|
Investigation of the Role of Myocyte Orientations in Cardiac Arrhythmia Using Image-Based Models. Biophys J 2019; 117:2396-2408. [PMID: 31679763 PMCID: PMC6990390 DOI: 10.1016/j.bpj.2019.09.041] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 09/13/2019] [Accepted: 09/23/2019] [Indexed: 11/24/2022] Open
Abstract
Cardiac electrical excitation-propagation is influenced by myocyte orientations (cellular organization). Quantitatively understanding this relationship presents a significant research challenge, especially during arrhythmias in which excitation patterns become complex. Tissue-scale simulations of cardiac electrophysiology, incorporating both dynamic action potential behavior and image-based myocardial architecture, provide an approach to investigate three-dimensional (3D) propagation of excitation waves in the heart. In this study, we aimed to assess the importance of natural variation in myocyte orientations on cardiac arrhythmogenesis using 3D tissue electrophysiology simulations. Three anatomical models (i.e., describing myocyte orientations) of healthy rat ventricles—obtained using diffusion tensor imaging at 100 μm resolution—were registered to a single biventricular geometry (i.e., a single cardiac shape), in which the myocyte orientations could be represented by each of the diffusion tensor imaging data sets or by an idealized rule-based description. The Fenton-Karma cellular excitation model was modified to reproduce rat ventricular action potential duration restitution to create reaction-diffusion cardiac electrophysiology models. Over 250 3D simulations were performed to investigate the effects of myocyte orientations on the following: 1) ventricular activation, 2) location-dependent arrhythmia induction via rapid pacing, and 3) dynamics of re-entry averaged over multiple episodes. It was shown that 1) myocyte orientation differences manifested themselves in local activation times, but the influence on total activation time was small; 2) differences in myocyte orientations could critically affect the inducibility and persistence of arrhythmias for specific stimulus-location/cycle-length combinations; and 3) myocyte orientations alone could be an important determinant of scroll wave break, although no significant differences were observed in averaged arrhythmia dynamics between the four myocyte orientation scenarios considered. Our results show that myocyte orientations are an important determinant of arrhythmia inducibility, persistence, and scroll wave break. These findings suggest that where specificity is desired (for example, when predicting location-dependent, patient-specific arrhythmia inducibility), subject-specific myocyte orientations may be important.
Collapse
|
12
|
Nielles-Vallespin S, Scott A, Ferreira P, Khalique Z, Pennell D, Firmin D. Cardiac Diffusion: Technique and Practical Applications. J Magn Reson Imaging 2019; 52:348-368. [PMID: 31482620 DOI: 10.1002/jmri.26912] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 08/13/2019] [Accepted: 08/14/2019] [Indexed: 12/12/2022] Open
Abstract
The 3D microarchitecture of the cardiac muscle underlies the mechanical and electrical properties of the heart. Cardiomyocytes are arranged helically through the depth of the wall, and their shortening leads to macroscopic torsion, twist, and shortening during cardiac contraction. Furthermore, cardiomyocytes are organized in sheetlets separated by shear layers, which reorientate, slip, and shear during macroscopic left ventricle (LV) wall thickening. Cardiac diffusion provides a means for noninvasive interrogation of the 3D microarchitecture of the myocardium. The fundamental principle of MR diffusion is that an MRI signal is attenuated by the self-diffusion of water in the presence of large diffusion-encoding gradients. Since water molecules are constrained by the boundaries in biological tissue (cell membranes, collagen layers, etc.), depicting their diffusion behavior elucidates the shape of the myocardial microarchitecture they are embedded in. Cardiac diffusion therefore provides a noninvasive means to understand not only the dynamic changes in cardiac microstructure of healthy myocardium during cardiac contraction but also the pathophysiological changes in the presence of disease. This unique and innovative technology offers tremendous potential to enable improved clinical diagnosis through novel microstructural and functional assessment. in vivo cardiac diffusion methods are immediately translatable to patients, opening new avenues for diagnostic investigation and treatment evaluation in a range of clinically important cardiac pathologies. This review article describes the 3D microstructure of the LV, explains in vivo and ex vivo cardiac MR diffusion acquisition and postprocessing techniques, as well as clinical applications to date. Level of Evidence: 1 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2019. J. Magn. Reson. Imaging 2020;52:348-368.
Collapse
Affiliation(s)
- Sonia Nielles-Vallespin
- Cardiovascular MR Unit, Royal Brompton And Harefield NHS Foundation Trust, London, UK.,NHLI, Imperial College of Science, Technology and Medicine, London, UK
| | - Andrew Scott
- Cardiovascular MR Unit, Royal Brompton And Harefield NHS Foundation Trust, London, UK.,NHLI, Imperial College of Science, Technology and Medicine, London, UK
| | - Pedro Ferreira
- Cardiovascular MR Unit, Royal Brompton And Harefield NHS Foundation Trust, London, UK.,NHLI, Imperial College of Science, Technology and Medicine, London, UK
| | - Zohya Khalique
- Cardiovascular MR Unit, Royal Brompton And Harefield NHS Foundation Trust, London, UK.,NHLI, Imperial College of Science, Technology and Medicine, London, UK
| | - Dudley Pennell
- Cardiovascular MR Unit, Royal Brompton And Harefield NHS Foundation Trust, London, UK.,NHLI, Imperial College of Science, Technology and Medicine, London, UK
| | - David Firmin
- Cardiovascular MR Unit, Royal Brompton And Harefield NHS Foundation Trust, London, UK.,NHLI, Imperial College of Science, Technology and Medicine, London, UK
| |
Collapse
|
13
|
Pianca N, Di Bona A, Lazzeri E, Costantini I, Franzoso M, Prando V, Armani A, Rizzo S, Fedrigo M, Angelini A, Basso C, Pavone FS, Rubart M, Sacconi L, Zaglia T, Mongillo M. Cardiac sympathetic innervation network shapes the myocardium by locally controlling cardiomyocyte size through the cellular proteolytic machinery. J Physiol 2019; 597:3639-3656. [DOI: 10.1113/jp276200] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 05/21/2019] [Indexed: 01/07/2023] Open
Affiliation(s)
- Nicola Pianca
- Veneto Institute of Molecular Medicine Padova Italy
- Department of Biomedical SciencesUniversity of Padova Padova Italy
| | - Anna Di Bona
- Veneto Institute of Molecular Medicine Padova Italy
- Department of Cardiac, Thoracic, Vascular Sciences and Public HealthUniversity of Padova Padova Italy
| | - Erica Lazzeri
- European Laboratory for Non‐linear SpectroscopyUniversity of Florence Florence Italy
| | - Irene Costantini
- European Laboratory for Non‐linear SpectroscopyUniversity of Florence Florence Italy
- National Institute of Optics, National Research CouncilUniversity of Florence Florence Italy
| | - Mauro Franzoso
- Veneto Institute of Molecular Medicine Padova Italy
- Department of Biomedical SciencesUniversity of Padova Padova Italy
| | - Valentina Prando
- Veneto Institute of Molecular Medicine Padova Italy
- Department of Cardiac, Thoracic, Vascular Sciences and Public HealthUniversity of Padova Padova Italy
| | - Andrea Armani
- Veneto Institute of Molecular Medicine Padova Italy
- Department of Biomedical SciencesUniversity of Padova Padova Italy
| | - Stefania Rizzo
- Department of Cardiac, Thoracic, Vascular Sciences and Public HealthUniversity of Padova Padova Italy
| | - Marny Fedrigo
- Department of Cardiac, Thoracic, Vascular Sciences and Public HealthUniversity of Padova Padova Italy
| | - Annalisa Angelini
- Department of Cardiac, Thoracic, Vascular Sciences and Public HealthUniversity of Padova Padova Italy
| | - Cristina Basso
- Department of Cardiac, Thoracic, Vascular Sciences and Public HealthUniversity of Padova Padova Italy
| | - Francesco S. Pavone
- European Laboratory for Non‐linear SpectroscopyUniversity of Florence Florence Italy
- National Institute of Optics, National Research CouncilUniversity of Florence Florence Italy
- Department of Physics and AstronomyUniversity of Florence Florence Italy
| | - Michael Rubart
- Indiana University School of Medicine Indianapolis IN USA
| | - Leonardo Sacconi
- European Laboratory for Non‐linear SpectroscopyUniversity of Florence Florence Italy
- National Institute of Optics, National Research CouncilUniversity of Florence Florence Italy
| | - Tania Zaglia
- Veneto Institute of Molecular Medicine Padova Italy
- Department of Biomedical SciencesUniversity of Padova Padova Italy
- Department of Cardiac, Thoracic, Vascular Sciences and Public HealthUniversity of Padova Padova Italy
| | - Marco Mongillo
- Veneto Institute of Molecular Medicine Padova Italy
- Department of Biomedical SciencesUniversity of Padova Padova Italy
- CNR Institute of Neuroscience Padova Italy
| |
Collapse
|
14
|
Abstract
There has been an increasing interest in studying cardiac fibers in order to improve the current knowledge regarding the mechanical and physiological properties of the heart during heart failure (HF), particularly early HF. Having a thorough understanding of the changes in cardiac fiber orientation may provide new insight into the mechanisms behind the progression of left ventricular (LV) remodeling and HF. We conducted a systematic review on various technologies for imaging cardiac fibers and its link to HF. This review covers literature reports from 1900 to 2017. PubMed and Google Scholar databases were searched using the keywords "cardiac fiber" and "heart failure" or "myofiber" and "heart failure." This review highlights imaging methodologies, including magnetic resonance diffusion tensor imaging (MR-DTI), ultrasound, and other imaging technologies as well as their potential applications in basic and translational research on the development and progression of HF. MR-DTI and ultrasound have been most useful and significant in evaluating cardiac fibers and HF. New imaging technologies that have the ability to measure cardiac fiber orientations and identify structural and functional information of the heart will advance basic research and clinical diagnoses of HF.
Collapse
Affiliation(s)
- Shana R Watson
- Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, GA, USA
| | - James D Dormer
- Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, GA, USA
| | - Baowei Fei
- Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, GA, USA. .,Winship Cancer Institute of Emory University, Atlanta, GA, USA. .,Department of Mathematics and Computer Science, Emory University, Atlanta, GA, USA. .,Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, GA, USA. .,Quantitative Bioimaging Laboratory, Department of Radiology and Imaging Sciences, School of Medicine, Emory University, Atlanta, United States.
| |
Collapse
|
15
|
Avazmohammadi R, Mendiola EA, Soares JS, Li DS, Chen Z, Merchant S, Hsu EW, Vanderslice P, Dixon RAF, Sacks MS. A Computational Cardiac Model for the Adaptation to Pulmonary Arterial Hypertension in the Rat. Ann Biomed Eng 2018; 47:138-153. [PMID: 30264263 DOI: 10.1007/s10439-018-02130-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Accepted: 09/11/2018] [Indexed: 01/01/2023]
Abstract
Pulmonary arterial hypertension (PAH) imposes pressure overload on the right ventricle (RV), leading to RV enlargement via the growth of cardiac myocytes and remodeling of the collagen fiber architecture. The effects of these alterations on the functional behavior of the right ventricular free wall (RVFW) and organ-level cardiac function remain largely unexplored. Computational heart models in the rat (RHMs) of the normal and hypertensive states can be quite valuable in simulating the effects of PAH on cardiac function to gain insights into the pathophysiology of underlying myocardium remodeling. We thus developed high-fidelity biventricular finite element RHMs for the normal and post-PAH hypertensive states using extensive experimental data collected from rat hearts. We then applied the RHM to investigate the transmural nature of RVFW remodeling and its connection to wall stress elevation under PAH. We found a strong correlation between the longitudinally-dominated fiber-level adaptation of the RVFW and the transmural alterations of relevant wall stress components. We further conducted several numerical experiments to gain new insights on how the RV responds both normally and in the post-PAH state. We found that the effect of pressure overload alone on the increased contractility of the RV is comparable to the effects of changes in the RV geometry and stiffness. Furthermore, our RHMs provided fresh perspectives on long-standing questions of the functional role of the interventricular septum in RV function. Specifically, we demonstrated that an inaccurate identification of the mechanical adaptation of the septum can lead to a significant underestimation of RVFW contractility in the post-PAH state. These findings show how integrated experimental-computational models can facilitate a more comprehensive understanding of the cardiac remodeling events during PAH.
Collapse
Affiliation(s)
- Reza Avazmohammadi
- Willerson Center for Cardiovascular Modeling and Simulation, Institute for Computational Engineering and Sciences and the Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, USA
| | - Emilio A Mendiola
- Willerson Center for Cardiovascular Modeling and Simulation, Institute for Computational Engineering and Sciences and the Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, USA
| | - João S Soares
- Department of Mechanical & Nuclear Engineering, Virginia Commonwealth University, Richmond, VA, USA
| | - David S Li
- Willerson Center for Cardiovascular Modeling and Simulation, Institute for Computational Engineering and Sciences and the Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, USA
| | - Zhiqiang Chen
- Department of Molecular Cardiology, Texas Heart Institute, Houston, TX, USA
| | - Samer Merchant
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, USA
| | - Edward W Hsu
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, USA
| | - Peter Vanderslice
- Department of Molecular Cardiology, Texas Heart Institute, Houston, TX, USA
| | - Richard A F Dixon
- Department of Molecular Cardiology, Texas Heart Institute, Houston, TX, USA
| | - Michael S Sacks
- Willerson Center for Cardiovascular Modeling and Simulation, Institute for Computational Engineering and Sciences and the Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, USA.
| |
Collapse
|
16
|
Zhang X, Liu ZQ, Singh D, Powell DK, Chung CS, Campbell KS, Wenk JF. Differential Effects of Isoproterenol on Regional Myocardial Mechanics in Rat using 3D cine DENSE Cardiovascular Magnetic Resonance. J Biomech Eng 2018; 141:2696750. [PMID: 30098173 DOI: 10.1115/1.4041042] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2018] [Indexed: 01/03/2023]
Abstract
The present study assessed the acute effects of isoproterenol on left ventricular (LV) mechanics in healthy rats with the hypothesis that ß-adrenergic stimulation influences the mechanics of different myocardial regions of the LV wall in different ways. To accomplish this, magnetic resonance images were obtained in the LV of healthy rats with or without isoproterenol infusion. The LV contours were divided into basal, mid-ventricular, and apical regions. Additionally, the mid-ventricular myocardium was divided into three transmural layers with each layer partitioned into four segments (i.e., septal, inferior, lateral, and anterior). Peak systolic strains and torsion were quantified for each region. Isoproterenol significantly increased peak systolic radial strain and circumferential-longitudinal shear strain, as well as ventricular torsion, throughout the basal, mid-ventricle, and apical regions. In the mid-ventricle, isoproterenol significantly increased peak systolic radial strain, and induced significant increases in peak systolic circumferential strain and longitudinal strain in the septum. Isoproterenol consistently increased peak systolic circumferential-longitudinal shear strain in all mid-ventricular segments. Ventricular torsion was significantly increased in nearly all segments except the inferior sub-endocardium. The effects of isoproterenol on LV systolic mechanics (i.e., 3D strains and torsion) in healthy rats depend on the region. This region-dependency is also strain component-specific. These results provide insight into the regional response of LV mechanics to ß-adrenergic stimulation in rats, and could act as a baseline for future studies on subclinical abnormalities associated with the inotropic response in heart disease.
Collapse
Affiliation(s)
- Xiaoyan Zhang
- Department of Mechanical Engineering, University of Kentucky, Lexington, KY, USA
| | - Zhan-Qiu Liu
- Department of Mechanical Engineering, University of Kentucky, Lexington, KY, USA
| | - Dara Singh
- Department of Mechanical Engineering, University of Kentucky, Lexington, KY, USA
| | - David K Powell
- Department of Anatomy and Neurobiology, University of Kentucky, Lexington, KY, USA
| | - Charles S Chung
- Department of Physiology, Wayne State University, Detroit, MI, USA; Department of Physiology, University of Kentucky, Lexington, KY, USA
| | | | - Jonathan F Wenk
- Department of Surgery, University of Kentucky, Lexington, KY, USA
| |
Collapse
|
17
|
Hoffman JIE. Will the real ventricular architecture please stand up? Physiol Rep 2018; 5:5/18/e13404. [PMID: 28947592 PMCID: PMC5617926 DOI: 10.14814/phy2.13404] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 07/23/2017] [Indexed: 12/28/2022] Open
Abstract
Ventricular twisting, essential for cardiac function, is attributed to the contraction of myocardial helical fibers. The exact relationship between ventricular anatomy and function remains to be determined, but one commonly used explanatory model is the helical ventricular myocardial band (HVMB) model of Torrent‐Guasp. This model has been successful in explaining many aspects of ventricular function, (Torrent‐Guasp et al. Eur. J. Cardiothorac. Surg., 25, 376, 2004; Buckberg et al. Eur. J. Cardiothorac. Surg., 47, 587, 2015; Buckberg et al. Eur. J. Cardiothorac. Surg. 47, 778, 2015) but the model ignores important aspects of ventricular anatomy and should probably be replaced. The purpose of this review is to compare the HVMB model with a different model (nested layers). A complication when interpreting experimental observations that relate anatomy to function is that, in the myocardium, shortening does not always imply activation and lengthening does not always imply inactivation.
Collapse
Affiliation(s)
- Julien I E Hoffman
- Department of Pediatrics, University of California, San Francisco, California
| |
Collapse
|
18
|
Gomez AD, Zou H, Bowen ME, Liu X, Hsu EW, McKellar SH. Right Ventricular Fiber Structure as a Compensatory Mechanism in Pressure Overload: A Computational Study. J Biomech Eng 2018; 139:2621589. [PMID: 28418458 DOI: 10.1115/1.4036485] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Indexed: 01/08/2023]
Abstract
Right ventricular failure (RVF) is a lethal condition in diverse pathologies. Pressure overload is the most common etiology of RVF, but our understanding of the tissue structure remodeling and other biomechanical factors involved in RVF is limited. Some remodeling patterns are interpreted as compensatory mechanisms including myocyte hypertrophy, extracellular fibrosis, and changes in fiber orientation. However, the specific implications of these changes, especially in relation to clinically observable measurements, are difficult to investigate experimentally. In this computational study, we hypothesized that, with other variables constant, fiber orientation alteration provides a quantifiable and distinct compensatory mechanism during RV pressure overload (RVPO). Numerical models were constructed using a rabbit model of chronic pressure overload RVF based on intraventricular pressure measurements, CINE magnetic resonance imaging (MRI), and diffusion tensor MRI (DT-MRI). Biventricular simulations were conducted under normotensive and hypertensive boundary conditions using variations in RV wall thickness, tissue stiffness, and fiber orientation to investigate their effect on RV pump function. Our results show that a longitudinally aligned myocardial fiber orientation contributed to an increase in RV ejection fraction (RVEF). This effect was more pronounced in response to pressure overload. Likewise, models with longitudinally aligned fiber orientation required a lesser contractility for maintaining a target RVEF against elevated pressures. In addition to increased wall thickness and material stiffness (diastolic compensation), systolic mechanisms in the forms of myocardial fiber realignment and changes in contractility are likely involved in the overall compensatory responses to pressure overload.
Collapse
Affiliation(s)
- Arnold D Gomez
- Mem. ASME Electrical and Computer Engineering Department, Johns Hopkins University, 3400 North Charles Street, RM Clark 201B, Baltimore, MD 21218 e-mail:
| | - Huashan Zou
- Bioengineering Department, University of Utah, 36 S. Wasatch Drive, SMBB RM 3100, Salt Lake City, UT 84112-2101 e-mail:
| | - Megan E Bowen
- Surgery Department, University of Utah, 30 N 1900 E, RM 3B205, Salt Lake City, UT 84112-2101 e-mail:
| | - Xiaoqing Liu
- Cardiothoracic Division, Surgery Department, University of Utah, 2000 Circle of Hope, RM LL376, Salt Lake City, UT 84112-2101 e-mail:
| | - Edward W Hsu
- Bioengineering Department, University of Utah, 36 S. Wasatch Drive, SMBB RM 1242, Salt Lake City, UT 84112-2101 e-mail:
| | - Stephen H McKellar
- Cardiothoracic Division, Surgery Department, University of Utah, 30 N 1900 E, RM 3B205 Salt Lake City, UT 84112-2101 e-mail:
| |
Collapse
|
19
|
Ahmad I. Review of the emerging role of optical polarimetry in characterization of pathological myocardium. JOURNAL OF BIOMEDICAL OPTICS 2017; 22:1-8. [PMID: 29076304 DOI: 10.1117/1.jbo.22.10.100901] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 10/04/2017] [Indexed: 05/02/2023]
Abstract
Myocardial infarction (MI), a cause of significant morbidity and mortality, is typically followed by microstructural alterations where the necrotic myocardium is steadily replaced with a collagen scar. Engineered remodeling of the fibrotic scar via stem cell regeneration has been shown to improve/restore the myocardium function after MI. Nevertheless, the heterogeneous nature of the scar patch may impair the myocardial electrical integrity, leading to the formation of arrhythmogenesis. Radiofrequency ablation (RFA) offers an effective treatment for focal arrhythmias where local heating generated via electric current at specific spots in the myocardium ablate the arrhythmogenic foci. Characterization of these myocardial pathologies (i.e., infarcted, stem cell regenerated, and RFA-ablated myocardial tissues) is of potential clinical importance. Optical polarimetry, the use of light to map and characterize the polarization signatures of a sample, has emerged as a powerful imaging tool for structural characterization of myocardial tissues, exploiting the underlying highly fibrous tissue nature. This study aims to review the recent progress in optical polarimetry pertaining to the characterization of myocardial pathologies while describing the underlying biological rationales that give rise to the optical imaging contrast in various pathologies of the myocardium. Future possibilities of and challenges to optical polarimetry in cardiac imaging clinics are also discussed.
Collapse
Affiliation(s)
- Iftikhar Ahmad
- Center for Nuclear Medicine and Radiotherapy (CENAR), Quetta, Pakistan
| |
Collapse
|
20
|
Ramos SR, Pieles G, Hui W, Ishii R, Slorach C, Friedberg MK. Comprehensive echocardiographic assessment of biventricular function in the rabbit, animal model in cardiovascular research: feasibility and normal values. Int J Cardiovasc Imaging 2017; 34:367-375. [PMID: 28840383 DOI: 10.1007/s10554-017-1238-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2017] [Accepted: 08/21/2017] [Indexed: 11/26/2022]
Abstract
Quantification of cardiac structure and function is central in cardiovascular research. Rabbits are valuable research models of cardiovascular human disease; however, there is little normal data available. The aim of this study was to investigate feasibility and provide normal values for comprehensive echocardiographic assessment of biventricular function in rabbits. New Zealand white rabbits underwent trans-thoracic echocardiography using a general electric (GE) Vivid 7/E9 system with a 10 MHz transducer, under light sedation, to evaluate biventricular function and dimensions. Images for two-dimensional, M-mode, tissue Doppler imaging (TDI) and speckle-tracking strain echocardiography were acquired and analysed. 55 male rabbits (sized matched with a newborn human baby) were studied, mean weight was 2.9 ± 0.23 kg. Adequate images were obtained in 90% for the left ventricle (LV) and 80% for the right ventricle (RV). Two-dimensional speckle-tracking strain was feasible in 60%. Average heart rate was 248 ± 36 beats per minute; LV ejection faction 72 ± 8.0; RV fractional area change 45.9 ± 9.0%; RV myocardial performance index 0.39 ± 0.35; tricuspid annular planar systolic excursion 0.60 ± 0.24 cm. LV TDI parameters were S' 8.6 ± 3.1 cm/s; E' 12.0 ± 4.46 cm/s. RV TDI parameters were S' 10.49 ± 3.18; E' 14.95 ± 4.64 cm/s. LV and RV global peak systolic longitudinal strain were -17 ± 5 and -22 ± 8%, respectively. Comprehensive investigation of biventricular dimensions and function by echocardiography is feasible in the rabbit. Apical views and strain imaging have lower feasibility. Normal values of LV and RV functional parameters are with comparable values to human children. Animal cardiovascular research is key to develop new goals in clinical practice.
Collapse
Affiliation(s)
- Sara Roldan Ramos
- The Labatt Family Heart Center, Hospital for Sick Children and University of Toronto, 555 University Avenue, Toronto, ON, M5G 1X8, Canada.
- Department of Congenital Cardiac Surgery and Paediatric Cardiology, Bristol Heart Institute and Bristol Royal Hospital for Children, Upper Maudlin Street, Bristol, UK.
| | - Guido Pieles
- The Labatt Family Heart Center, Hospital for Sick Children and University of Toronto, 555 University Avenue, Toronto, ON, M5G 1X8, Canada
- Department of Congenital Cardiac Surgery and Paediatric Cardiology, Bristol Heart Institute and Bristol Royal Hospital for Children, Upper Maudlin Street, Bristol, UK
| | - Wei Hui
- The Labatt Family Heart Center, Hospital for Sick Children and University of Toronto, 555 University Avenue, Toronto, ON, M5G 1X8, Canada
| | - Ryo Ishii
- The Labatt Family Heart Center, Hospital for Sick Children and University of Toronto, 555 University Avenue, Toronto, ON, M5G 1X8, Canada
| | - Cameron Slorach
- The Labatt Family Heart Center, Hospital for Sick Children and University of Toronto, 555 University Avenue, Toronto, ON, M5G 1X8, Canada
| | - Mark K Friedberg
- The Labatt Family Heart Center, Hospital for Sick Children and University of Toronto, 555 University Avenue, Toronto, ON, M5G 1X8, Canada.
| |
Collapse
|
21
|
The human fetal right ventricular myocardium appears without a sub-epicardial base-apex oriented layer of myocytes. Pediatr Res 2017; 81:396-397. [PMID: 27861466 DOI: 10.1038/pr.2016.248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 09/23/2016] [Indexed: 11/08/2022]
|
22
|
Abdullah OM, Seidel T, Dahl M, Gomez AD, Yiep G, Cortino J, Sachse FB, Albertine KH, Hsu EW. Diffusion tensor imaging and histology of developing hearts. NMR IN BIOMEDICINE 2016; 29:1338-1349. [PMID: 27485033 PMCID: PMC5160010 DOI: 10.1002/nbm.3576] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 05/24/2016] [Accepted: 06/03/2016] [Indexed: 06/06/2023]
Abstract
Diffusion tensor imaging (DTI) has emerged as a promising method for noninvasive quantification of myocardial microstructure. However, the origin and behavior of DTI measurements during myocardial normal development and remodeling remain poorly understood. In this work, conventional and bicompartmental DTI in addition to three-dimensional histological correlation were performed in a sheep model of myocardial development from third trimester to postnatal 5 months of age. Comparing the earliest time points in the third trimester with the postnatal 5 month group, the scalar transverse diffusivities preferentially increased in both left ventricle (LV) and right ventricle (RV): secondary eigenvalues D2 increased by 54% (LV) and 36% (RV), whereas tertiary eigenvalues D3 increased by 85% (LV) and 67% (RV). The longitudinal diffusivity D1 changes were small, which led to a decrease in fractional anisotropy by 41% (LV) and 33% (RV) in 5 month versus fetal hearts. Histological analysis suggested that myocardial development is associated with hyperplasia in the early stages of the third trimester followed by myocyte growth in the later stages up to 5 months of age (increased average myocyte width by 198%, myocyte length by 128%, and decreased nucleus density by 70% between preterm and postnatal 5 month hearts.) In a few histological samples (N = 6), correlations were observed between DTI longitudinal diffusivity and myocyte length (r = 0.86, P < 0.05), and transverse diffusivity and myocyte width (r = 0.96, P < 0.01). Linear regression analysis showed that transverse diffusivities are more affected by changes in myocyte size and nucleus density changes than longitudinal diffusivities, which is consistent with predictions of classical models of diffusion in porous media. Furthermore, primary and secondary DTI eigenvectors during development changed significantly. Collectively, the findings demonstrate a role for DTI to monitor and quantify myocardial development, and potentially cardiac disease. Copyright © 2016 John Wiley & Sons, Ltd.
Collapse
Affiliation(s)
- Osama M Abdullah
- Department of Bioengineering, University of Utah, Salt Lake City, UT, USA.
| | - Thomas Seidel
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, USA
| | - MarJanna Dahl
- Department of Pediatrics, University of Utah, Salt Lake City, UT, USA
| | - Arnold David Gomez
- Department of Electrical Computer Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Gavin Yiep
- Department of Bioengineering, University of Utah, Salt Lake City, UT, USA
| | - Julia Cortino
- Department of Bioengineering, University of Utah, Salt Lake City, UT, USA
| | - Frank B Sachse
- Department of Bioengineering, University of Utah, Salt Lake City, UT, USA
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, USA
| | - Kurt H Albertine
- Department of Pediatrics, University of Utah, Salt Lake City, UT, USA
| | - Edward W Hsu
- Department of Bioengineering, University of Utah, Salt Lake City, UT, USA
| |
Collapse
|
23
|
Wang Y, Cai W, Wang L, Xia R, Chen W, Zheng J, Gao F. Evaluation of the Differences of Myocardial Fibers between Acute and Chronic Myocardial Infarction: Application of Diffusion Tensor Magnetic Resonance Imaging in a Rhesus Monkey Model. Korean J Radiol 2016; 17:725-33. [PMID: 27587961 PMCID: PMC5007399 DOI: 10.3348/kjr.2016.17.5.725] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2015] [Accepted: 04/29/2016] [Indexed: 02/05/2023] Open
Abstract
Objective To understand microstructural changes after myocardial infarction (MI), we evaluated myocardial fibers of rhesus monkeys during acute or chronic MI, and identified the differences of myocardial fibers between acute and chronic MI. Materials and Methods Six fixed hearts of rhesus monkeys with left anterior descending coronary artery ligation for 1 hour or 84 days were scanned by diffusion tensor magnetic resonance imaging (MRI) to measure apparent diffusion coefficient (ADC), fractional anisotropy (FA) and helix angle (HA). Results Comparing with acute MI monkeys (FA: 0.59 ± 0.02; ADC: 5.0 ± 0.6 × 10-4 mm2/s; HA: 94.5 ± 4.4°), chronic MI monkeys showed remarkably decreased FA value (0.26 ± 0.03), increased ADC value (7.8 ± 0.8 × 10-4mm2/s), decreased HA transmural range (49.5 ± 4.6°) and serious defects on endocardium in infarcted regions. The HA in infarcted regions shifted to more components of negative left-handed helix in chronic MI monkeys (-38.3 ± 5.0°–11.2 ± 4.3°) than in acute MI monkeys (-41.4 ± 5.1°–53.1 ± 3.7°), but the HA in remote regions shifted to more components of positive right-handed helix in chronic MI monkeys (-43.8 ± 2.7°–66.5 ± 4.9°) than in acute MI monkeys (-59.5 ± 3.4°–64.9 ± 4.3°). Conclusion Diffusion tensor MRI method helps to quantify differences of mechanical microstructure and water diffusion of myocardial fibers between acute and chronic MI monkey's models.
Collapse
Affiliation(s)
- Yuqing Wang
- Department of Radiology, West China Hospital, Sichuan University, Sichuan 610041, China.; CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, National Center for Nanoscience and Technology of China, Beijing 100190, China
| | - Wei Cai
- Department of Radiology, West China Hospital, Sichuan University, Sichuan 610041, China.; Department of Radiology, Beijing Jishuitan Hospital, 4th Clinical Medical College of Peking University, Beijing 100035, China
| | - Lei Wang
- Department of Radiology, West China Hospital, Sichuan University, Sichuan 610041, China
| | - Rui Xia
- Department of Radiology, West China Hospital, Sichuan University, Sichuan 610041, China.; Department of Radiology, The First Affiliated Hospital, Chongqing Medical University, Chongqing 400016, China
| | - Wei Chen
- Department of Radiology, West China Hospital, Sichuan University, Sichuan 610041, China.; Department of Radiology, The First Affiliated Hospital of Kunming Medical University, Yunnan 650032, China
| | - Jie Zheng
- Mallinckrodt Institute of Radiology, School of Medicine, Washington University, St. Louis, MO 63110, USA
| | - Fabao Gao
- Department of Radiology, West China Hospital, Sichuan University, Sichuan 610041, China
| |
Collapse
|
24
|
Teh I, Burton RAB, McClymont D, Capel RA, Aston D, Kohl P, Schneider JE. Mapping cardiac microstructure of rabbit heart in different mechanical states by high resolution diffusion tensor imaging: A proof-of-principle study. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2016; 121:85-96. [PMID: 27320383 PMCID: PMC4959513 DOI: 10.1016/j.pbiomolbio.2016.06.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Accepted: 06/13/2016] [Indexed: 01/27/2023]
Abstract
Myocardial microstructure and its macroscopic materialisation are fundamental to the function of the heart. Despite this importance, characterisation of cellular features at the organ level remains challenging, and a unifying description of the structure of the heart is still outstanding. Here, we optimised diffusion tensor imaging data to acquire high quality data in ex vivo rabbit hearts in slack and contractured states, approximating diastolic and systolic conditions. The data were analysed with a suite of methods that focused on different aspects of the myocardium. In the slack heart, we observed a similar transmural gradient in helix angle of the primary eigenvector of up to 23.6°/mm in the left ventricle and 24.2°/mm in the right ventricle. In the contractured heart, the same transmural gradient remained largely linear, but was offset by up to +49.9° in the left ventricle. In the right ventricle, there was an increase in the transmural gradient to 31.2°/mm and an offset of up to +39.0°. The application of tractography based on each eigenvector enabled visualisation of streamlines that depict cardiomyocyte and sheetlet organisation over large distances. We observed multiple V- and N-shaped sheetlet arrangements throughout the myocardium, and insertion of sheetlets at the intersection of the left and right ventricle. This study integrates several complementary techniques to visualise and quantify the heart's microstructure, projecting parameter representations across different length scales. This represents a step towards a more comprehensive characterisation of myocardial microstructure at the whole organ level.
Collapse
Affiliation(s)
- Irvin Teh
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Rebecca A B Burton
- Department of Pharmacology, University of Oxford, Oxford, United Kingdom
| | - Darryl McClymont
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Rebecca A Capel
- Department of Pharmacology, University of Oxford, Oxford, United Kingdom
| | - Daniel Aston
- Department of Pharmacology, University of Oxford, Oxford, United Kingdom
| | - Peter Kohl
- National Heart and Lung Institute, Imperial College London, London, United Kingdom; Institute for Experimental Cardiovascular Medicine, University Heart Centre Freiburg - Bad Krozingen, Medical School of the University of Freiburg, Germany
| | - Jürgen E Schneider
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom.
| |
Collapse
|
25
|
Xie F, Zemlin CW. Effect of Twisted Fiber Anisotropy in Cardiac Tissue on Ablation with Pulsed Electric Fields. PLoS One 2016; 11:e0152262. [PMID: 27101250 PMCID: PMC4839574 DOI: 10.1371/journal.pone.0152262] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2015] [Accepted: 03/13/2016] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Ablation of cardiac tissue with pulsed electric fields is a promising alternative to current thermal ablation methods, and it critically depends on the electric field distribution in the heart. METHODS We developed a model that incorporates the twisted anisotropy of cardiac tissue and computed the electric field distribution in the tissue. We also performed experiments in rabbit ventricles to validate our model. We find that the model agrees well with the experimentally determined ablation volume if we assume that all tissue that is exposed to a field greater than 3 kV/cm is ablated. In our numerical analysis, we considered how tissue thickness, degree of anisotropy, and electrode configuration affect the geometry of the ablated volume. We considered two electrode configurations: two parallel needles inserted into the myocardium ("penetrating needles" configuration) and one circular electrode each on epi- and endocardium, opposing each other ("epi-endo" configuration). RESULTS For thick tissues (10 mm) and moderate anisotropy ratio (a = 2), we find that the geometry of the ablated volume is almost unaffected by twisted anisotropy, i.e. it is approximately translationally symmetric from epi- to endocardium, for both electrode configurations. Higher anisotropy ratio (a = 10) leads to substantial variation in ablation width across the wall; these variations were more pronounced for the penetrating needle configuration than for the epi-endo configuration. For thinner tissues (4 mm, typical for human atria) and higher anisotropy ratio (a = 10), the epi-endo configuration yielded approximately translationally symmetric ablation volumes, while the penetrating electrodes configuration was much more sensitive to fiber twist. CONCLUSIONS These results suggest that the epi-endo configuration will be reliable for ablation of atrial fibrillation, independently of fiber orientation, while the penetrating electrode configuration may experience problems when the fiber orientation is not consistent across the atrial wall.
Collapse
Affiliation(s)
- Fei Xie
- Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, Virginia, United States of America
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, Virginia, United States of America
| | - Christian W. Zemlin
- Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, Virginia, United States of America
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, Virginia, United States of America
- * E-mail:
| |
Collapse
|
26
|
Ciaccio EJ, Coromilas J, Wit AL, Peters NS, Garan H. Formation of reentrant circuits in the mid-myocardial infarct border zone. Comput Biol Med 2016; 71:205-13. [DOI: 10.1016/j.compbiomed.2016.02.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Revised: 01/19/2016] [Accepted: 02/08/2016] [Indexed: 11/28/2022]
|
27
|
Merchant SS, Gomez AD, Morgan JL, Hsu EW. Parametric Modeling of the Mouse Left Ventricular Myocardial Fiber Structure. Ann Biomed Eng 2016; 44:2661-73. [PMID: 26942586 DOI: 10.1007/s10439-016-1574-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 02/17/2016] [Indexed: 12/26/2022]
Abstract
Magnetic resonance diffusion tensor imaging (DTI) has greatly facilitated detailed quantifications of myocardial structures. However, structural patterns, such as the distinctive transmural rotation of the fibers, remain incompletely described. To investigate the validity and practicality of pattern-based analysis, 3D DTI was performed on 13 fixed mouse hearts and fiber angles in the left ventricle were transformed and fitted to parametric expressions constructed from elementary functions of the prolate spheroidal spatial variables. It was found that, on average, the myocardial fiber helix angle could be represented to 6.5° accuracy by the equivalence of a product of 10th-order polynomials of the radial and longitudinal variables, and 17th-order Fourier series of the circumferential variable. Similarly, the fiber imbrication angle could be described by 10th-order polynomials and 24th-order Fourier series, to 5.6° accuracy. The representations, while relatively concise, did not adversely affect the information commonly derived from DTI datasets including the whole-ventricle mean fiber helix angle transmural span and atlases constructed for the group. The unique ability of parametric models for predicting the 3D myocardial fiber structure from finite number of 2D slices was also demonstrated. These findings strongly support the principle of parametric modeling for characterizing myocardial structures in the mouse and beyond.
Collapse
Affiliation(s)
- Samer S Merchant
- Department of Bioengineering, University of Utah, 36 S Wasatch Dr Rm 3100, Salt Lake City, UT, 84112, USA.
| | - Arnold David Gomez
- Department of Bioengineering, University of Utah, 36 S Wasatch Dr Rm 3100, Salt Lake City, UT, 84112, USA
- Division of Cardiothoracic Surgery, University of Utah, Salt Lake City, UT, USA
| | - James L Morgan
- Department of Bioengineering, University of Utah, 36 S Wasatch Dr Rm 3100, Salt Lake City, UT, 84112, USA
| | - Edward W Hsu
- Department of Bioengineering, University of Utah, 36 S Wasatch Dr Rm 3100, Salt Lake City, UT, 84112, USA
| |
Collapse
|
28
|
Wang Y, Cai W, Wang L, Xia R. Evaluate the early changes of myocardial fibers in rhesus monkey during sub-acute stage of myocardial infarction using diffusion tensor magnetic resonance imaging. Magn Reson Imaging 2015; 34:391-6. [PMID: 26708038 DOI: 10.1016/j.mri.2015.12.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 12/12/2015] [Indexed: 02/05/2023]
Abstract
PURPOSE The deterioration of cardiac mechanical function starts from the micro-alterations in the myocardial fibers after myocardial infarction (MI) due to the heart beats derived from the systole and diastole of the myocardial fibers. So, we want to evaluate quantitatively the early changes of myocardial fibers in rhesus monkey during sub-acute MI stage. MATERIALS AND METHODS Three fixed hearts with infarction after left anterior descending coronary artery ligation for 7days and eight age-matched intact controls were scanned by ex-vivo diffusion tensor magnetic resonance imaging (DT-MRI) to measure apparent diffusion coefficient (ADC), fractional anisotropy (FA) and helix angle (HA). RESULTS In comparison with healthy controls, FA and transmural range of HA in MI regions showed a significant reduction whereas ADC showed a significant increment (p<0.01). The double-helix myocardial fibers shifted further to left-handed helix around the infarcted and adjacent myocardium but shifted further to right-handed helix in remote myocardium. CONCLUSION HA is sensitive to evaluate quantitatively the early changes of myocardial fibers in sub-acute MI rhesus monkeys. The myocardial fibers in normal monkeys are similar to those in normal humans, suggesting that early changes of myocardial fibers in sub-acute MI monkeys can contribute to more accurately understand those in patients suffering sub-acute MI.
Collapse
Affiliation(s)
- Yuqing Wang
- CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, National Center for Nanoscience and Technology of China, No.11 ZhongGuanCun BeiYiTiao, Beijing, 100190, China.
| | - Wei Cai
- Department of Radiology, Beijing Jishuitan Hospital, 4th clinical medical college of Peking University, No.31 Xinjiekou East Road, Beijing, China, 100035
| | - Lei Wang
- Department of Radiology, West China Hospital, Sichuan University, No.37 Guoxue Alley, Chengdu, Sichuan, China, 610041
| | - Rui Xia
- Department of Radiology, The First Affiliated Hospital, Chongqing Medical University, No.1 Friendship Road, Chongqing, China, 400016
| |
Collapse
|
29
|
Land S, Gurev V, Arens S, Augustin CM, Baron L, Blake R, Bradley C, Castro S, Crozier A, Favino M, Fastl TE, Fritz T, Gao H, Gizzi A, Griffith BE, Hurtado DE, Krause R, Luo X, Nash MP, Pezzuto S, Plank G, Rossi S, Ruprecht D, Seemann G, Smith NP, Sundnes J, Rice JJ, Trayanova N, Wang D, Jenny Wang Z, Niederer SA. Verification of cardiac mechanics software: benchmark problems and solutions for testing active and passive material behaviour. Proc Math Phys Eng Sci 2015; 471:20150641. [PMID: 26807042 PMCID: PMC4707707 DOI: 10.1098/rspa.2015.0641] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Models of cardiac mechanics are increasingly used to investigate cardiac physiology. These models are characterized by a high level of complexity, including the particular anisotropic material properties of biological tissue and the actively contracting material. A large number of independent simulation codes have been developed, but a consistent way of verifying the accuracy and replicability of simulations is lacking. To aid in the verification of current and future cardiac mechanics solvers, this study provides three benchmark problems for cardiac mechanics. These benchmark problems test the ability to accurately simulate pressure-type forces that depend on the deformed objects geometry, anisotropic and spatially varying material properties similar to those seen in the left ventricle and active contractile forces. The benchmark was solved by 11 different groups to generate consensus solutions, with typical differences in higher-resolution solutions at approximately 0.5%, and consistent results between linear, quadratic and cubic finite elements as well as different approaches to simulating incompressible materials. Online tools and solutions are made available to allow these tests to be effectively used in verification of future cardiac mechanics software.
Collapse
Affiliation(s)
- Sander Land
- Department of Biomedical Engineering, King's College London , London, UK
| | - Viatcheslav Gurev
- Thomas J. Watson Research Center, IBM Research, Yorktown Heights , NY 10598, USA
| | - Sander Arens
- Department of Physics and Astronomy , Ghent University , Ghent, Belgium
| | | | - Lukas Baron
- Institute of Biomedical Engineering, Karlsruhe Institute of Technology , Karlsruhe, Germany
| | - Robert Blake
- Department of Biomedical Engineering and Institute for Computational Medicine , Johns Hopkins University , Baltimore, MD 21218, USA
| | - Chris Bradley
- Auckland Bioengineering Institute, University of Auckland , Auckland, New Zealand
| | - Sebastian Castro
- Department of Structural and Geotechnical Engineering , Pontifica Universidad Católica de Chile , Chile
| | - Andrew Crozier
- Institute of Biophysics, Medical University of Graz , Graz, Austria
| | - Marco Favino
- Center for Computational Medicine in Cardiology , Institute of Computational Science, Università della Svizzera italiana , Lugano, Switzerland
| | - Thomas E Fastl
- Department of Biomedical Engineering, King's College London , London, UK
| | - Thomas Fritz
- Institute of Biomedical Engineering, Karlsruhe Institute of Technology , Karlsruhe, Germany
| | - Hao Gao
- School of Mathematics and Statistics, University of Glasgow , Glasgow, UK
| | - Alessio Gizzi
- Department of Engineering, Nonlinear Physics and Mathematical Modeling Lab , University Campus Bio-Medico of Rome , Rome, Italy
| | - Boyce E Griffith
- Interdisciplinary Applied Mathematics Center , University of North Carolina at Chapel Hill , Chapel Hill, NC, USA
| | - Daniel E Hurtado
- Department of Structural and Geotechnical Engineering , Pontifica Universidad Católica de Chile , Chile
| | - Rolf Krause
- Center for Computational Medicine in Cardiology , Institute of Computational Science, Università della Svizzera italiana , Lugano, Switzerland
| | - Xiaoyu Luo
- School of Mathematics and Statistics, University of Glasgow , Glasgow, UK
| | - Martyn P Nash
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand; Department of Engineering Science, University of Auckland, Auckland, New Zealand
| | - Simone Pezzuto
- Center for Computational Medicine in Cardiology, Institute of Computational Science, Università della Svizzera italiana, Lugano, Switzerland; Simula Research Laboratory, Fornebu, Norway
| | - Gernot Plank
- Institute of Biophysics, Medical University of Graz , Graz, Austria
| | - Simone Rossi
- Civil and Environmental Engineering Department , Duke University , Durham, NC 27708-0287, USA
| | - Daniel Ruprecht
- Center for Computational Medicine in Cardiology , Institute of Computational Science, Università della Svizzera italiana , Lugano, Switzerland
| | - Gunnar Seemann
- Institute of Biomedical Engineering, Karlsruhe Institute of Technology , Karlsruhe, Germany
| | - Nicolas P Smith
- Department of Biomedical Engineering, King's College London, London, UK; Department of Engineering Science, University of Auckland, Auckland, New Zealand
| | | | - J Jeremy Rice
- Thomas J. Watson Research Center, IBM Research, Yorktown Heights , NY 10598, USA
| | - Natalia Trayanova
- Department of Biomedical Engineering and Institute for Computational Medicine , Johns Hopkins University , Baltimore, MD 21218, USA
| | - Dafang Wang
- Department of Biomedical Engineering and Institute for Computational Medicine , Johns Hopkins University , Baltimore, MD 21218, USA
| | - Zhinuo Jenny Wang
- Auckland Bioengineering Institute, University of Auckland , Auckland, New Zealand
| | - Steven A Niederer
- Department of Biomedical Engineering, King's College London , London, UK
| |
Collapse
|
30
|
Affiliation(s)
- V.Y. Wang
- Auckland Bioengineering Institute and
| | - P.M.F. Nielsen
- Auckland Bioengineering Institute and
- Department of Engineering Science, Faculty of Engineering, University of Auckland, Auckland 1010, New Zealand; , ,
| | - M.P. Nash
- Auckland Bioengineering Institute and
- Department of Engineering Science, Faculty of Engineering, University of Auckland, Auckland 1010, New Zealand; , ,
| |
Collapse
|
31
|
Abstract
The heart pumps blood to maintain circulation and ensure the delivery of oxygenated blood to all the organs of the body. Mechanics play a critical role in governing and regulating heart function under both normal and pathological conditions. Biological processes and mechanical stress are coupled together in regulating myocyte function and extracellular matrix structure thus controlling heart function. Here, we offer a brief introduction to the biomechanics of left ventricular function and then summarize recent progress in the study of the effects of mechanical stress on ventricular wall remodeling and cardiac function as well as the effects of wall mechanical properties on cardiac function in normal and dysfunctional hearts. Various mechanical models to determine wall stress and cardiac function in normal and diseased hearts with both systolic and diastolic dysfunction are discussed. The results of these studies have enhanced our understanding of the biomechanical mechanism in the development and remodeling of normal and dysfunctional hearts. Biomechanics provide a tool to understand the mechanism of left ventricular remodeling in diastolic and systolic dysfunction and guidance in designing and developing new treatments.
Collapse
Affiliation(s)
- Andrew P. Voorhees
- Department of Mechanical Engineering, The University of Texas at San Antonio, Biomedical Engineering Program, UTSA-UTHSCSA
| | - Hai-Chao Han
- Department of Mechanical Engineering, The University of Texas at San Antonio, Biomedical Engineering Program, UTSA-UTHSCSA
| |
Collapse
|
32
|
David Gomez A, Bull DA, Hsu EW. Finite-Element Extrapolation of Myocardial Structure Alterations Across the Cardiac Cycle in Rats. J Biomech Eng 2015; 137:101010. [PMID: 26299478 DOI: 10.1115/1.4031419] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Indexed: 11/08/2022]
Abstract
Myocardial microstructures are responsible for key aspects of cardiac mechanical function. Natural myocardial deformation across the cardiac cycle induces measurable structural alteration, which varies across disease states. Diffusion tensor magnetic resonance imaging (DT-MRI) has become the tool of choice for myocardial structural analysis. Yet, obtaining the comprehensive structural information of the whole organ, in 3D and time, for subject-specific examination is fundamentally limited by scan time. Therefore, subject-specific finite-element (FE) analysis of a group of rat hearts was implemented for extrapolating a set of initial DT-MRI to the rest of the cardiac cycle. The effect of material symmetry (isotropy, transverse isotropy, and orthotropy), structural input, and warping approach was observed by comparing simulated predictions against in vivo MRI displacement measurements and DT-MRI of an isolated heart preparation at relaxed, inflated, and contracture states. Overall, the results indicate that, while ventricular volume and circumferential strain are largely independent of the simulation strategy, structural alteration predictions are generally improved with the sophistication of the material model, which also enhances torsion and radial strain predictions. Moreover, whereas subject-specific transversely isotropic models produced the most accurate descriptions of fiber structural alterations, the orthotropic models best captured changes in sheet structure. These findings underscore the need for subject-specific input data, including structure, to extrapolate DT-MRI measurements across the cardiac cycle.
Collapse
|
33
|
Bakermans AJ, Abdurrachim D, Moonen RPM, Motaal AG, Prompers JJ, Strijkers GJ, Vandoorne K, Nicolay K. Small animal cardiovascular MR imaging and spectroscopy. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2015; 88-89:1-47. [PMID: 26282195 DOI: 10.1016/j.pnmrs.2015.03.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Revised: 03/09/2015] [Accepted: 03/09/2015] [Indexed: 06/04/2023]
Abstract
The use of MR imaging and spectroscopy for studying cardiovascular disease processes in small animals has increased tremendously over the past decade. This is the result of the remarkable advances in MR technologies and the increased availability of genetically modified mice. MR techniques provide a window on the entire timeline of cardiovascular disease development, ranging from subtle early changes in myocardial metabolism that often mark disease onset to severe myocardial dysfunction associated with end-stage heart failure. MR imaging and spectroscopy techniques play an important role in basic cardiovascular research and in cardiovascular disease diagnosis and therapy follow-up. This is due to the broad range of functional, structural and metabolic parameters that can be quantified by MR under in vivo conditions non-invasively. This review describes the spectrum of MR techniques that are employed in small animal cardiovascular disease research and how the technological challenges resulting from the small dimensions of heart and blood vessels as well as high heart and respiratory rates, particularly in mice, are tackled.
Collapse
Affiliation(s)
- Adrianus J Bakermans
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands; Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Desiree Abdurrachim
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Rik P M Moonen
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Abdallah G Motaal
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands; Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Jeanine J Prompers
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Gustav J Strijkers
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands; Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Katrien Vandoorne
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Klaas Nicolay
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.
| |
Collapse
|
34
|
Heterogeneity of Fractional Anisotropy and Mean Diffusivity Measurements by In Vivo Diffusion Tensor Imaging in Normal Human Hearts. PLoS One 2015; 10:e0132360. [PMID: 26177211 PMCID: PMC4503691 DOI: 10.1371/journal.pone.0132360] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Accepted: 06/14/2015] [Indexed: 11/19/2022] Open
Abstract
Background Cardiac diffusion tensor imaging (cDTI) by cardiovascular magnetic resonance has the potential to assess microstructural changes through measures of fractional anisotropy (FA) and mean diffusivity (MD). However, normal variation in regional and transmural FA and MD is not well described. Methods Twenty normal subjects were scanned using an optimised cDTI sequence at 3T in systole. FA and MD were quantified in 3 transmural layers and 4 regional myocardial walls. Results FA was higher in the mesocardium (0.46 ±0.04) than the endocardium (0.40 ±0.04, p≤0.001) and epicardium (0.39 ±0.04, p≤0.001). On regional analysis, the FA in the septum was greater than the lateral wall (0.44 ±0.03 vs 0.40 ±0.05 p = 0.04). There was a transmural gradient in MD increasing towards the endocardium (epicardium 0.87 ±0.07 vs endocardium 0.91 ±0.08×10-3 mm2/s, p = 0.04). With the lateral wall (0.87 ± 0.08×10-3 mm2/s) as the reference, the MD was higher in the anterior wall (0.92 ±0.08×10-3 mm2/s, p = 0.016) and septum (0.92 ±0.07×10-3 mm2/s, p = 0.028). Transmurally the signal to noise ratio (SNR) was greatest in the mesocardium (14.5 ±2.5 vs endocardium 13.1 ±2.2, p<0.001; vs epicardium 12.0 ± 2.4, p<0.001) and regionally in the septum (16.0 ±3.4 vs lateral wall 11.5 ± 1.5, p<0.001). Transmural analysis suggested a relative reduction in the rate of change in helical angle (HA) within the mesocardium. Conclusions In vivo FA and MD measurements in normal human heart are heterogeneous, varying significantly transmurally and regionally. Contributors to this heterogeneity are many, complex and interactive, but include SNR, variations in cardiac microstructure, partial volume effects and strain. These data indicate that the potential clinical use of FA and MD would require measurement standardisation by myocardial region and layer, unless pathological changes substantially exceed the normal variation identified.
Collapse
|
35
|
Zhang X, Haynes P, Campbell KS, Wenk JF. Numerical evaluation of myofiber orientation and transmural contractile strength on left ventricular function. J Biomech Eng 2015; 137:044502. [PMID: 25367232 DOI: 10.1115/1.4028990] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Indexed: 11/08/2022]
Abstract
The left ventricle (LV) of the heart is composed of a complex organization of cardiac muscle fibers, which contract to generate force and pump blood into the body. It has been shown that both the orientation and contractile strength of these myofibers vary across the ventricular wall. The hypothesis of the current study is that the transmural distributions of myofiber orientation and contractile strength interdependently impact LV pump function. In order to quantify these interactions a finite element (FE) model of the LV was generated, which incorporated transmural variations. The influences of myofiber orientation and contractile strength on the Starling relationship and the end-systolic (ES) apex twist of the LV were assessed. The results suggest that reductions in contractile strength within a specific transmural layer amplified the effects of altered myofiber orientation in the same layer, causing greater changes in stroke volume (SV). Furthermore, when the epicardial myofibers contracted the strongest, the twist of the LV apex was greatest, regardless of myofiber orientation. These results demonstrate the important role of transmural distribution of myocardial contractile strength and its interplay with myofiber orientation. The coupling between these two physiologic parameters could play a critical role in the progression of heart failure.
Collapse
|
36
|
Assessment of Myofiber Orientation in High Resolution Phase-Contrast CT Images. FUNCTIONAL IMAGING AND MODELING OF THE HEART 2015. [DOI: 10.1007/978-3-319-20309-6_13] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
|
37
|
Pennell DJ, Baksi AJ, Kilner PJ, Mohiaddin RH, Prasad SK, Alpendurada F, Babu-Narayan SV, Neubauer S, Firmin DN. Review of Journal of Cardiovascular Magnetic Resonance 2013. J Cardiovasc Magn Reson 2014; 16:100. [PMID: 25475898 PMCID: PMC4256918 DOI: 10.1186/s12968-014-0100-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Accepted: 11/21/2014] [Indexed: 01/19/2023] Open
Abstract
There were 109 articles published in the Journal of Cardiovascular Magnetic Resonance (JCMR) in 2013, which is a 21% increase on the 90 articles published in 2012. The quality of the submissions continues to increase. The editors are delighted to report that the 2012 JCMR Impact Factor (which is published in June 2013) has risen to 5.11, up from 4.44 for 2011 (as published in June 2012), a 15% increase and taking us through the 5 threshold for the first time. The 2012 impact factor means that the JCMR papers that were published in 2010 and 2011 were cited on average 5.11 times in 2012. The impact factor undergoes natural variation according to citation rates of papers in the 2 years following publication, and is significantly influenced by highly cited papers such as official reports. However, the progress of the journal's impact over the last 5 years has been impressive. Our acceptance rate is <25% and has been falling because the number of articles being submitted has been increasing. In accordance with Open-Access publishing, the JCMR articles go on-line as they are accepted with no collating of the articles into sections or special thematic issues. For this reason, the Editors have felt that it is useful once per calendar year to summarize the papers for the readership into broad areas of interest or theme, so that areas of interest can be reviewed in a single article in relation to each other and other recent JCMR articles. The papers are presented in broad themes and set in context with related literature and previously published JCMR papers to guide continuity of thought in the journal. We hope that you find the open-access system increases wider reading and citation of your papers, and that you will continue to send your quality manuscripts to JCMR for publication.
Collapse
Affiliation(s)
- Dudley John Pennell
- />Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, Sydney Street, London, SW3 6NP UK
- />Imperial College, London, UK
| | - Arun John Baksi
- />Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, Sydney Street, London, SW3 6NP UK
- />Imperial College, London, UK
| | - Philip John Kilner
- />Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, Sydney Street, London, SW3 6NP UK
- />Imperial College, London, UK
| | - Raad Hashem Mohiaddin
- />Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, Sydney Street, London, SW3 6NP UK
- />Imperial College, London, UK
| | - Sanjay Kumar Prasad
- />Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, Sydney Street, London, SW3 6NP UK
- />Imperial College, London, UK
| | - Francisco Alpendurada
- />Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, Sydney Street, London, SW3 6NP UK
- />Imperial College, London, UK
| | - Sonya Vidya Babu-Narayan
- />Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, Sydney Street, London, SW3 6NP UK
- />Imperial College, London, UK
| | | | - David Nigel Firmin
- />Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, Sydney Street, London, SW3 6NP UK
- />Imperial College, London, UK
| |
Collapse
|
38
|
Abdullah OM, Drakos SG, Diakos NA, Wever-Pinzon O, Kfoury AG, Stehlik J, Selzman CH, Reid BB, Brunisholz K, Verma DR, Myrick C, Sachse FB, Li DY, Hsu EW. Characterization of diffuse fibrosis in the failing human heart via diffusion tensor imaging and quantitative histological validation. NMR IN BIOMEDICINE 2014; 27:1378-86. [PMID: 25200106 PMCID: PMC4215542 DOI: 10.1002/nbm.3200] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2014] [Revised: 07/09/2014] [Accepted: 08/15/2014] [Indexed: 05/16/2023]
Abstract
Non-invasive imaging techniques are highly desirable as an alternative to conventional biopsy for the characterization of the remodeling of tissues associated with disease progression, including end-stage heart failure. Cardiac diffusion tensor imaging (DTI) has become an established method for the characterization of myocardial microstructure. However, the relationships between diffuse myocardial fibrosis, which is a key biomarker for staging and treatment planning of the failing heart, and measured DTI parameters have yet to be investigated systematically. In this study, DTI was performed on left ventricular specimens collected from patients with chronic end-stage heart failure as a result of idiopathic dilated cardiomyopathy (n = 14) and from normal donors (n = 5). Scalar DTI parameters, including fractional anisotropy (FA) and mean (MD), primary (D1 ), secondary (D2 ) and tertiary (D3 ) diffusivities, were correlated with collagen content measured by digital microscopy. Compared with hearts from normal subjects, the FA in failing hearts decreased by 22%, whereas the MD, D2 and D3 increased by 12%, 14% and 24%, respectively (P < 0.01). No significant change was detected for D1 between the two groups. Furthermore, significant correlation was observed between the DTI scalar indices and quantitative histological measurements of collagen (i.e. fibrosis). Pearson's correlation coefficients (r) between collagen content and FA, MD, D2 and D3 were -0.51, 0.59, 0.56 and 0.62 (P < 0.05), respectively. The correlation between D1 and collagen content was not significant (r = 0.46, P = 0.05). Computational modeling analysis indicated that the behaviors of the DTI parameters as a function of the degree of fibrosis were well explained by compartmental exchange between myocardial and collagenous tissues. Combined, these findings suggest that scalar DTI parameters can be used as metrics for the non-invasive assessment of diffuse fibrosis in failing hearts.
Collapse
Affiliation(s)
| | - Stavros G. Drakos
- Molecular Medicine Program, University of Utah
- UTAH Cardiac Transplant Program (University of Utah Hospital, Intermountain Medical Center, Salt Lake Veterans Affairs Medical Center)
| | | | - Omar Wever-Pinzon
- UTAH Cardiac Transplant Program (University of Utah Hospital, Intermountain Medical Center, Salt Lake Veterans Affairs Medical Center)
| | - Abdallah G. Kfoury
- UTAH Cardiac Transplant Program (University of Utah Hospital, Intermountain Medical Center, Salt Lake Veterans Affairs Medical Center)
| | - Josef Stehlik
- UTAH Cardiac Transplant Program (University of Utah Hospital, Intermountain Medical Center, Salt Lake Veterans Affairs Medical Center)
| | - Craig H. Selzman
- UTAH Cardiac Transplant Program (University of Utah Hospital, Intermountain Medical Center, Salt Lake Veterans Affairs Medical Center)
| | - Bruce B. Reid
- UTAH Cardiac Transplant Program (University of Utah Hospital, Intermountain Medical Center, Salt Lake Veterans Affairs Medical Center)
| | - Kim Brunisholz
- UTAH Cardiac Transplant Program (University of Utah Hospital, Intermountain Medical Center, Salt Lake Veterans Affairs Medical Center)
| | - Divya Ratan Verma
- UTAH Cardiac Transplant Program (University of Utah Hospital, Intermountain Medical Center, Salt Lake Veterans Affairs Medical Center)
| | | | - Frank B. Sachse
- Department of Bioengineering, University of Utah
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah
| | - Dean Y. Li
- Molecular Medicine Program, University of Utah
| | | |
Collapse
|
39
|
Angeli S, Befera N, Peyrat JM, Calabrese E, Johnson GA, Constantinides C. A high-resolution cardiovascular magnetic resonance diffusion tensor map from ex-vivo C57BL/6 murine hearts. J Cardiovasc Magn Reson 2014; 16:77. [PMID: 25323636 PMCID: PMC4198699 DOI: 10.1186/s12968-014-0077-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2014] [Accepted: 09/01/2014] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND The complex cardiac fiber structural organization and spatial arrangement of cardiomyocytes in laminar sheetlets contributes greatly to cardiac functional and contractile ejection patterns. This study presents the first comprehensive, ultra-high resolution, fully quantitative statistical tensor map of the fixed murine heart at isotropic resolution of 43 μm using diffusion tensor (DT) cardiovascular magnetic resonance (CMR). METHODS Imaging was completed in approximately 12 hours using a six-directional encoding scheme, in five ex vivo healthy C57BL/6 mouse hearts. The tensor map constructed from this data provides an average description of the murine fiber architecture visualized with fiber tractography, and its population variability, using the latest advances in image tensor analysis and statistics. RESULTS Results show that non-normalized cardiac tensor maps are associated with mean fractional anisotropy of 0.25 ± 0.07 and mean diffusivity of 8.9 ± 1.6 × 10⁻⁴mm²/s. Moreover, average mid-ventricular helical angle distributions ranged between -41 ± 3° and +52 ± 5° and were highly correlated with transmural depth, in agreement with prior published results in humans and canines. Calculated variabilities of local myocyte orientations were 2.0° and 1.4°. Laminar sheet orientation variability was found to be less stable at 2.6°. Despite such variations, the murine heart seems to be highly structured, particularly when compared to canines and humans. CONCLUSIONS This tensor map has the potential to yield an accurate mean representation and identification of common or unique features of the cardiac myocyte architecture, to establish a baseline standard reference of DTI indices, and to improve detection of biomarkers, especially in pathological states or post-transgenetic modifications.
Collapse
Affiliation(s)
- Stelios Angeli
- Department of Mechanical and Manufacturing Engineering, Laboratory of Physiology and Biomedical Imaging, School of Engineering, University of Cyprus, 75 Kalipoleos Avenue, Green Park Building, Nicosia, Cyprus.
| | - Nicholas Befera
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, NC, USA.
| | - Jean-Marc Peyrat
- Qatar Robotic Surgery Centre, Qatar Science & Technology Park, Doha, Qatar.
| | - Evan Calabrese
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, NC, USA.
| | | | - Christakis Constantinides
- Department of Mechanical and Manufacturing Engineering, Laboratory of Physiology and Biomedical Imaging, School of Engineering, University of Cyprus, 75 Kalipoleos Avenue, Green Park Building, Nicosia, Cyprus.
- Chi-Biomedical Limited, 36 Parthenonos Street, Apartment 303, Strovolos, 2021, Nicosia, Cyprus.
| |
Collapse
|
40
|
Lohezic M, Teh I, Bollensdorff C, Peyronnet R, Hales PW, Grau V, Kohl P, Schneider JE. Interrogation of living myocardium in multiple static deformation states with diffusion tensor and diffusion spectrum imaging. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2014; 115:213-25. [PMID: 25117498 PMCID: PMC4210665 DOI: 10.1016/j.pbiomolbio.2014.08.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Accepted: 08/02/2014] [Indexed: 11/27/2022]
Abstract
Diffusion tensor magnetic resonance imaging (MRI) reveals valuable insights into tissue histo-anatomy and microstructure, and has steadily gained traction in the cardiac community. Its wider use in small animal cardiac imaging in vivo has been constrained by its extreme sensitivity to motion, exaggerated by the high heart rates usually seen in rodents. Imaging of the isolated heart eliminates respiratory motion and, if conducted on arrested hearts, cardiac pulsation. This serves as an important intermediate step for basic and translational studies. However, investigating the micro-structural basis of cardiac deformation in the same heart requires observations in different deformation states. Here, we illustrate the imaging of isolated rat hearts in three mechanical states mimicking diastole (cardioplegic arrest), left-ventricular (LV) volume overload (cardioplegic arrest plus LV balloon inflation), and peak systole (lithium-induced contracture). An optimised MRI-compatible Langendorff perfusion setup with the radio-frequency (RF) coil integrated into the wet chamber was developed for use in a 9.4T horizontal bore scanner. Signal-to-noise ratio improved significantly, by 75% compared to a previous design with external RF coil, and stability tests showed no significant changes in mean T1, T2 or LV wall thickness over a 170 min period. In contracture, we observed a significant reduction in mean fractional anisotropy from 0.32 ± 0.02 to 0.28 ± 0.02, as well as a significant rightward shift in helix angles with a decrease in the proportion of left-handed fibres, as referring to the locally prevailing cell orientation in the heart, from 24.9% to 23.3%, and an increase in the proportion of right-handed fibres from 25.5% to 28.4%. LV overload, in contrast, gave rise to a decrease in the proportion of left-handed fibres from 24.9% to 21.4% and an increase in the proportion of right-handed fibres from 25.5% to 26.0%. The modified perfusion and coil setup offers better performance and control over cardiac contraction states. We subsequently performed high-resolution diffusion spectrum imaging (DSI) and 3D whole heart fibre tracking in fixed ex vivo rat hearts in slack state and contracture. As a model-free method, DSI augmented the measurements of water diffusion by also informing on multiple intra-voxel diffusion orientations and non-Gaussian diffusion. This enabled us to identify the transition from right- to left-handed fibres from the subendocardium to the subepicardium, as well as voxels in apical regions that were traversed by multiple fibres. We observed that both the mean generalised fractional anisotropy and mean kurtosis were lower in hearts in contracture compared to the slack state, by 23% and 9.3%, respectively. While its heavy acquisition burden currently limits the application of DSI in vivo, ongoing work in acceleration techniques may enable its use in live animals and patients. This would provide access to the as yet unexplored dimension of non-Gaussian diffusion that could serve as a highly sensitive marker of cardiac micro-structural integrity.
Collapse
Affiliation(s)
- Maelene Lohezic
- British Heart Foundation Experimental Magnetic Resonance Unit, Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Irvin Teh
- British Heart Foundation Experimental Magnetic Resonance Unit, Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Christian Bollensdorff
- National Heart and Lung Institute, Imperial College London, London, UK; Qatar Cardiovascular Research Center, Qatar Foundation, Doha, Qatar
| | - Rémi Peyronnet
- National Heart and Lung Institute, Imperial College London, London, UK
| | - Patrick W Hales
- Imaging and Biophysics Unit, Institute of Child Health, University College London, London, UK
| | - Vicente Grau
- Department of Engineering Science, University of Oxford, Oxford, UK
| | - Peter Kohl
- National Heart and Lung Institute, Imperial College London, London, UK; Department of Computer Science, University of Oxford, Oxford, UK
| | - Jürgen E Schneider
- British Heart Foundation Experimental Magnetic Resonance Unit, Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK.
| |
Collapse
|
41
|
Post-mortem cardiac diffusion tensor imaging: detection of myocardial infarction and remodeling of myofiber architecture. Eur Radiol 2014; 24:2810-8. [DOI: 10.1007/s00330-014-3322-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2013] [Revised: 06/24/2014] [Accepted: 07/07/2014] [Indexed: 12/12/2022]
|
42
|
Froeling M, Strijkers GJ, Nederveen AJ, Chamuleau SA, Luijten PR. Diffusion Tensor MRI of the Heart – In Vivo Imaging of Myocardial Fiber Architecture. CURRENT CARDIOVASCULAR IMAGING REPORTS 2014. [DOI: 10.1007/s12410-014-9276-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
|
43
|
Dunmore-Buyze PJ, Tate E, Xiang FL, Detombe SA, Nong Z, Pickering JG, Drangova M. Three-dimensional imaging of the mouse heart and vasculature using micro-CT and whole-body perfusion of iodine or phosphotungstic acid. CONTRAST MEDIA & MOLECULAR IMAGING 2014; 9:383-90. [PMID: 24764151 DOI: 10.1002/cmmi.1588] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Revised: 11/21/2013] [Accepted: 11/26/2013] [Indexed: 12/20/2022]
Abstract
Recent studies have investigated histological staining compounds as micro-computed tomography (micro-CT) contrast agents, delivered by soaking tissue specimens in stain and relying on passive diffusion for agent uptake. This study describes a perfusion approach using iodine or phosphotungstic acid (PTA) stains, delivered to an intact mouse, to capitalize on the microvasculature as a delivery conduit for parenchymal staining and direct contact for staining artery walls. Twelve C57BL/6 mice, arterially perfused with either 25% Lugol's solution or 5% PTA solution were scanned intact and reconstructed with 26 µm isotropic voxels. The animals were fixed and the heart and surrounding vessels were excised, embedded and scanned; isolated heart images were reconstructed with 13 µm isotropic voxels. Myocardial enhancement and artery diameters were measured. Both stains successfully enhanced the myocardium and vessel walls. Interestingly, Lugol's solution provided a significantly higher enhancement of the myocardium than PTA [2502 ± 437 vs 656 ± 178 Hounsfield units (HU); p < 0.0001], delineating myofiber architecture and orientation. There was no significant difference in vessel wall enhancement (Lugol's, 1036 ± 635 HU; PTA, 738 ± 124 HU; p = 0.29), but coronary arteries were more effectively segmented from the PTA-stained hearts, enabling segmented imaging of fifth- order coronary artery branches. The combination of whole mouse perfusion delivery and use of heavy metal-containing stains affords high-resolution imaging of the mouse heart and vasculature by micro-CT. The differential imaging patterns of Lugol's- and PTA-stained tissues reveals new opportunities for micro-analyses of cardiac and vascular tissues.
Collapse
Affiliation(s)
- P Joy Dunmore-Buyze
- Robarts Research Institute, The University of Western Ontario, London, ON, Canada
| | | | | | | | | | | | | |
Collapse
|
44
|
Grimes KM, Voorhees A, Chiao YA, Han HC, Lindsey ML, Buffenstein R. Cardiac function of the naked mole-rat: ecophysiological responses to working underground. Am J Physiol Heart Circ Physiol 2014; 306:H730-7. [PMID: 24363308 PMCID: PMC3949069 DOI: 10.1152/ajpheart.00831.2013] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Accepted: 12/18/2013] [Indexed: 11/22/2022]
Abstract
The naked mole-rat (NMR) is a strictly subterranean rodent with a low resting metabolic rate. Nevertheless, it can greatly increase its metabolic activity to meet the high energetic demands associated with digging through compacted soils in its xeric natural habitat where food is patchily distributed. We hypothesized that the NMR heart would naturally have low basal function and exhibit a large cardiac reserve, thereby mirroring the species' low basal metabolism and large metabolic scope. Echocardiography showed that young (2-4 yr old) healthy NMRs have low fractional shortening (28 ± 2%), ejection fraction (43 ± 2%), and cardiac output (6.5 ± 0.4 ml/min), indicating low basal cardiac function. Histology revealed large NMR cardiomyocyte cross-sectional area (216 ± 10 μm(2)) and cardiac collagen deposition of 2.2 ± 0.4%. Neither of these histomorphometric traits was considered pathological, since biaxial tensile testing showed no increase in passive ventricular stiffness. NMR cardiomyocyte fibers showed a low degree of rotation, contributing to the observed low NMR cardiac contractility. Interestingly, when the exercise mimetic dobutamine (3 μg/g ip) was administered, NMRs showed pronounced increases in fractional shortening, ejection fraction, cardiac output, and stroke volume, indicating an increased cardiac reserve. The relatively low basal cardiac function and enhanced cardiac reserve of NMRs are likely to be ecophysiological adaptations to life in an energetically taxing environment.
Collapse
Affiliation(s)
- Kelly M Grimes
- Department of Physiology and the Sam and Ann Barshop Institute for Aging and Longevity Studies, The University of Texas Health Science Center at San Antonio, San Antonio, Texas
| | | | | | | | | | | |
Collapse
|
45
|
Voorhees AP, Han HC. A model to determine the effect of collagen fiber alignment on heart function post myocardial infarction. Theor Biol Med Model 2014; 11:6. [PMID: 24456675 PMCID: PMC3914851 DOI: 10.1186/1742-4682-11-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2013] [Accepted: 01/08/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Adverse remodeling of the left ventricle (LV) following myocardial infarction (MI) leads to heart failure. Recent studies have shown that scar anisotropy is a determinant of cardiac function post-MI, however it remains unclear how changes in extracellular matrix (ECM) organization and structure contribute to changes in LV function. The objective of this study is to develop a model to identify potential mechanisms by which collagen structure and organization affect LV function post-MI. METHODS A four-region, multi-scale, cylindrical model of the post-MI LV was developed. The mechanical properties of the infarct region are governed by a constitutive equation based on the uncrimping of collagen fibers. The parameters of this constitutive equation include collagen orientation, angular dispersion, fiber stiffness, crimp angle, and density. Parametric variation of these parameters was used to elucidate the relationship between collagen properties and LV function. RESULTS The mathematical model of the LV revealed several factors that influenced cardiac function post-MI. LV function was maximized when collagen fibers were aligned longitudinally. Increased collagen density was also found to improve stroke volume for longitudinal alignments while increased fiber stiffness decreased stroke volume for circumferential alignments. CONCLUSIONS The results suggest that cardiac function post-MI is best preserved through increased circumferential compliance. Further, this study identifies several collagen fiber-level mechanisms that could potentially regulate both infarct level and organ level mechanics. Improved understanding of the multi-scale relationships between the ECM and LV function will be beneficial in the design of new diagnostic and therapeutic technologies.
Collapse
Affiliation(s)
- Andrew P Voorhees
- Biomedical Engineering Program, UTSA-UTHSCSA 1 UTSA Circle, San Antonio, TX 78249, USA
| | - Hai-Chao Han
- Biomedical Engineering Program, UTSA-UTHSCSA 1 UTSA Circle, San Antonio, TX 78249, USA
- Department of Mechanical Engineering, The University of Texas at San Antonio Biomedical Engineering Program, UTSA-UTHSCSA, 1 UTSA Circle, San Antonio, TX 78249, USA
| |
Collapse
|
46
|
|
47
|
Pennell DJ, Baksi AJ, Carpenter JP, Firmin DN, Kilner PJ, Mohiaddin RH, Prasad SK. Review of Journal of Cardiovascular Magnetic Resonance 2012. J Cardiovasc Magn Reson 2013; 15:76. [PMID: 24006874 PMCID: PMC3847143 DOI: 10.1186/1532-429x-15-76] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Accepted: 08/22/2013] [Indexed: 02/07/2023] Open
Abstract
There were 90 articles published in the Journal of Cardiovascular Magnetic Resonance (JCMR) in 2012, which is an 8% increase in the number of articles since 2011. The quality of the submissions continues to increase. The editors are delighted to report that the 2011 JCMR Impact Factor (which is published in June 2012) has risen to 4.44, up from 3.72 for 2010 (as published in June 2011), a 20% increase. The 2011 impact factor means that the JCMR papers that were published in 2009 and 2010 were cited on average 4.44 times in 2011. The impact factor undergoes natural variation according to citation rates of papers in the 2 years following publication, and is significantly influenced by highly cited papers such as official reports. However, the progress of the journal's impact over the last 5 years has been impressive. Our acceptance rate is approximately 25%, and has been falling as the number of articles being submitted has been increasing. In accordance with Open-Access publishing, the JCMR articles go on-line as they are accepted with no collating of the articles into sections or special thematic issues. For this reason, the Editors have felt that it is useful once per calendar year to summarize the papers for the readership into broad areas of interest or theme, so that areas of interest can be reviewed in a single article in relation to each other and other recent JCMR articles. The papers are presented in broad themes and set in context with related literature and previously published JCMR papers to guide continuity of thought in the journal. We hope that you find the open-access system increases wider reading and citation of your papers, and that you will continue to send your quality manuscripts to JCMR for publication.
Collapse
Affiliation(s)
- Dudley J Pennell
- Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, Sydney Street, London, SW3 6NP, UK
- Imperial College, London, UK
| | - A John Baksi
- Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, Sydney Street, London, SW3 6NP, UK
- Imperial College, London, UK
| | - John Paul Carpenter
- Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, Sydney Street, London, SW3 6NP, UK
- Imperial College, London, UK
| | - David N Firmin
- Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, Sydney Street, London, SW3 6NP, UK
- Imperial College, London, UK
| | - Philip J Kilner
- Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, Sydney Street, London, SW3 6NP, UK
- Imperial College, London, UK
| | - Raad H Mohiaddin
- Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, Sydney Street, London, SW3 6NP, UK
- Imperial College, London, UK
| | - Sanjay K Prasad
- Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, Sydney Street, London, SW3 6NP, UK
- Imperial College, London, UK
| |
Collapse
|
48
|
Crooijmans HJ, Ruder TD, Zech WD, Somaini S, Scheffler K, Thali MJ, Bieri O. Feasibility of quantitative diffusion imaging of the heart in post-mortem MR. ACTA ACUST UNITED AC 2013. [DOI: 10.1016/j.jofri.2013.05.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
49
|
Akki A, Gupta A, Weiss RG. Magnetic resonance imaging and spectroscopy of the murine cardiovascular system. Am J Physiol Heart Circ Physiol 2013; 304:H633-48. [PMID: 23292717 DOI: 10.1152/ajpheart.00771.2011] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Magnetic resonance imaging (MRI) has emerged as a powerful and reliable tool to noninvasively study the cardiovascular system in clinical practice. Because transgenic mouse models have assumed a critical role in cardiovascular research, technological advances in MRI have been extended to mice over the last decade. These have provided critical insights into cardiac and vascular morphology, function, and physiology/pathophysiology in many murine models of heart disease. Furthermore, magnetic resonance spectroscopy (MRS) has allowed the nondestructive study of myocardial metabolism in both isolated hearts and in intact mice. This article reviews the current techniques and important pathophysiological insights from the application of MRI/MRS technology to murine models of cardiovascular disease.
Collapse
Affiliation(s)
- Ashwin Akki
- Division of Cardiology, Department of Medicine, and Division of Magnetic Resonance Research, Department of Radiology, The Johns Hopkins University, School of Medicine, Baltimore, MD, USA
| | | | | |
Collapse
|
50
|
Wang Y, Yao G. Optical tractography of the mouse heart using polarization-sensitive optical coherence tomography. BIOMEDICAL OPTICS EXPRESS 2013; 4:2540-5. [PMID: 24298414 PMCID: PMC3829548 DOI: 10.1364/boe.4.002540] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 10/13/2013] [Accepted: 10/15/2013] [Indexed: 05/18/2023]
Abstract
We developed a method to image myocardial fiber architecture in the mouse heart using a Jones matrix-based polarization-sensitive optical coherence tomography (PSOCT) system. The "cross-helical" laminar structure of myocardial fibers can be clearly visualized using this technology. The obtained myocardial fiber organization agrees well with existing knowledge acquired using conventional histology and diffusion tensor magnetic resonance imaging.
Collapse
|