Synopsis
Detailed information can now be obtained on the microstructural architecture of the heart from MRI data. Changes in microstructure in disease have significant impacts on cardiac performance. This talk will give course participants an overview of our current understanding of the relationships between cardiac microstructure and cardiac function. Recent clinical applications will be reviewed and areas of productive future research will be highlighted.
Target Audience
Clinicians, physicists and engineers seeking to learn more about the microstructure of the heart and prepare for future innovations in imaging microstructure in cardiac diseaseOutcome/Objectives
Detailed information can now be obtained on the microstructural architecture of the heart from MRI data. Changes in microstructure in disease have significant impacts on cardiac performance. This talk will give course participants an overview of our current understanding of the relationships between cardiac microstructure and cardiac function. Recent clinical applications will be reviewed and areas of productive future research will be highlighted.Methods and Results
Since William Harvey speculated that the muscular architecture of the heart must have a substantial influence on its mechanical operation [1], there has been a great deal of research on function-structure relationships in cardiac mechanics [2]. For example, left ventricular torsion is feature of cardiac function which is greatly influenced by cardiac microstructure and provides important information on myocardial mechanics over and above standard pump function indices [3]. Computational models have shown that a specific relationship between torsion and ejection is required to balance forces and maintain a uniform myocyte shortening across the wall [4]. These models are essential to understanding the relationships between structure and function [5]. The substantial wall thickening which occurs during systole cannot be solely due to myocyte thickening, so substantial shear deformations must act to facilitate wall thickening, and therefore pump function. These transverse shears are mechanically facilitated by myocardial sheetlets. Maximum local shearing is aligned with the sheetlet orientation in the subendocardium [6-8]. High-resolution extended volume confocal microscopy has shown changes in myocyte (endomysial) collagen as well as sheetlet (perimysial) collagen in spontaneously hypertensive rats [9]. This includes the disappearance of cleavage planes, increased perimysial collagen deposits, enlargement of myocyte cross sectional area and an increase in endomysial collagen.Using non-invasive diffusion tensor imaging, sheetlet orientation was found to be abnormal in dilated cardiomyopathy, with altered systolic conformation and reduced mobility. In contrast patients with hypertrophic cardiomyopathy which showed reduced mobility with altered diastolic conformation [10].Conclusions:
The relationships between myocardial microstructure and cardiac function are important for the understanding of normal and diseased heart function. Microstructural remodeling may shed light on the development of future treatmentsAcknowledgements
No acknowledgement found.References
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