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Predicting the Biomechanics of the Aorta Using Ultrasound
Published in Ayman El-Baz, Jasjit S. Suri, Cardiovascular Imaging and Image Analysis, 2018
Mansour AlOmran, Alexander Emmott, Richard L. Leask, Kevin Lachapelle
Two-dimensional (2D) speckle-tracking echocardiography (STE) is an imaging modality that exploits the presence of natural acoustic markers (i.e., “speckles”) from standard B-mode (brightness mode) ultrasound images. Speckles are both stable and evenly distributed within the area of the imaged tissue [58]. As a result, speckles can be tracked within a time-series of B-mode images allowing for the measurement of tissue velocity (Figure 17.5). Strain (ε) can be obtained from STE by measuring the deformation between adjacent speckles: ε=δ/L0, where L0 is the original length between the two speckles, and δ is the change in length (i.e., δ=L−L0) [59]. This process can be scaled and applied to larger segmentations of a tissue; for instance, a quadrant of the circumference of the aortic wall. And unlike Doppler technology, it uses 2D grayscale images and thus is angle independent (i.e., it is not necessary for the main motion vector to be parallel to the ultrasound beam vector, which also renders it independent from cardiac translational movement) [53, 60–63].
Cardiac Biomechanics
Published in Joseph D. Bronzino, Donald R. Peterson, Biomedical Engineering Fundamentals, 2019
Andrew D. McCulloch and Roy C. P. Kerckhof
strain analyses like HARP [131] and two-and three-dimensional speckle tracking echocardiography [132]. In unusual circumstances, radiopaque markers are implanted in the myocardium during cardiac surgery or transplantation [133].
A long-duration race induces a decrease of left ventricular strains, twisting mechanics and myocardial work in trained adolescents
Published in European Journal of Sport Science, 2023
Anthony Birat, Sébastien Ratel, Alexandre Dodu, Claire Grossoeuvre, Anne-Charlotte Dupont, Mélanie Rance, Claire Morel, Stéphane Nottin
Speckle tracking echocardiography (STE) has emerged as a reliable technique for studying myocardial mechanics since it enables detecting subtle alterations in systolic function when ejection fraction (EF) is still preserved (Al Saikhan et al., 2019). However, their relative load dependency makes the myocardial deformation indices unable to account for changes in arterial blood pressures, such as those observed after exercise (Lord et al., 2018). To overcome this limitation, global myocardial work, estimated from the construction of LV pressure-strain loop (LV-PSL), is an interesting echocardiographic tool for assessing the myocardial function (Russell et al., 2012, 2013). LV-PSL could be decreased after long-duration exercise, which could bring new evidence of a transient depression of systolic function.
Characterization of the anisotropic deformation of the right ventricle during open heart surgery
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2020
A. Soltani, J. Lahti, K. Järvelä, J. Laurikka, V.-T. Kuokkala, M. Hokka
Quantification of the functions of the heart is tied to its deformation and motion. Smiseth et. al. (2016) provides a comprehensive study of the use of the myocardial strains in the quantification of the ventricular functions in various situations. Consequently, it is important to monitor any irregularities in the deformation and motion of the heart during challenging heart surgeries such as cardiopulmonary bypass (CPB) (Machin and Allsagar, 2006; Smith and Rinder, 2013; Sarkar and Prabhu, 2017). Various methods have been introduced for the monitoring of the heart`s functions by measuring its strains and strain rates (Marwick, 2006; Dandel et al., 2009; Friedberg and Mertens, 2009). Among these methods are the echocardiography-based techniques such as Tissue Doppler Imaging (TDI) (Sutherland et al., 1999) and more recently, Speckle Tracking Echocardiography (STE). STE has a distinct advantage over TDI as it can measure strains more independent of direction (Bansal and Kasliwal, 2013) compared to the TDI and thus, it gives information on anisotropic/isotropic deformation of the heart. However, even the routinely used 2 D STE can only provide planar views of the heart, and therefore is limited by the 2 D analysis, and for example, any out of plane displacements can cause significant errors in the measurements. Furthermore, the 2 D view of interest must be decided at the time when images are acquired, and the directional freedom is not available after the imaging. The information about the isotropy is important for the surgeons and the members of the surgical team since the myocardial deformation is very complex, especially for the ill and poorly functioning hearts that are operated, and any additional data is important as it has the potential to expand our knowledge in this field.
Quantitative assessment of full field deformation of right ventricle during open heart surgery
Published in Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization, 2021
A. Soltani, J. Lahti, K. Järvelä, J. Laurikka, M. Hokka
Monitoring and analysing the functions of the heart is an important aspect of open-heart surgery. Since the functions of the heart are closely related to its deformation and movements (Smiseth et al. 2016), various echocardiography methods have been developed to measure and analyse the movements, deformation, strain, and strain rate of the heart (Dandel et al. 2009). These methods include Tissue Doppler Imaging (TDI) (Sutherland et al. 1999; Krishna and Thomas 2015) and Speckle Tracking Echocardiography (STE) (Blessberger and Binder 2010; Bansal and Kasliwal 2013). While these methods have their own set of advances and shortcomings (Teske et al. 2009), what they have in common is that they can only take into account the deformation on a planar area (2D deformation). In reality, the heart deforms in a rather complex manner, and there are significant out of plane movements and rotations that are difficult to analyse from a 2D image. Additionally, TDI and STE results are limited to pre-selected areas/directions of the heart that are chosen before the measurements. Consequently, only a portion of the potential data is available for analysis at a time. However, the deformation of the heart is very complex and far from uniform. This fact is even more exacerbated when the heart of the sick patient is already functioning in a non-optimal manner, therefore necessitating the surgery in the first place. During the open-heart surgery and cardiopulmonary bypass (CPB), the functions of the heart are temporarily performed by the CPB circuit. After the surgical repairs and during the weaning process, the heart resumes its functionality and therefore, the deformation of heart is far from normal. This high complexity in deformation of the heart necessitates the study of the full field deformation over the visible section of the ventricle or atrium. While this area does not fully cover the entire RV, it is usually enough to represent the RV movement. The deformation is most likely very anisotropic and non-uniform, but it still is a common practice to describe the function of the RV by a single scalar strain value. For example, the modern ultrasound techniques typically use segmentation to analyse strains of different parts of the heart, but the strain itself is a simple engineering strain that describes only the deformation between two selected points and ignores information encoded in all other image points.