The dependency of fetal left ventricular biomechanics function on myocardium helix angle configuration

Abstract

The helix angle configuration of the myocardium is understood to contribute to the heart function, as finite element (FE) modeling of postnatal hearts showed that altered configurations affected cardiac function and biomechanics. However, similar investigations have not been done on the fetal heart. To address this, we performed image-based FE simulations of fetal left ventricles (LV) over a range of helix angle configurations, assuming a linear variation of helix angles from epicardium to endocardium. Results showed that helix angles have substantial influence on peak myofiber stress, cardiac stroke work, myocardial deformational burden, and spatial variability of myocardial strain. A good match between LV myocardial strains from FE simulations to those measured from 4D fetal echo images could only be obtained if the transmural variation of helix angle was generally between 110 and 130°, suggesting that this was the physiological range. Experimentally discovered helix angle configurations from the literature were found to produce high peak myofiber stress, high cardiac stroke work, and a low myocardial deformational burden, but did not coincide with configurations that would optimize these characteristics. This may suggest that the fetal development of myocyte orientations depends concurrently on several factors rather than a single factor. We further found that the shape, rather than the size of the LV, determined the manner at which helix angles influenced these characteristics, as this influence changed significantly when the LV shape was varied, but not when a heart was scaled from fetal to adult size while retaining the same shape. This may suggest that biomechanical optimality would be affected during diseases that altered the geometric shape of the LV.

Pre‐intervention myocardial stress is a good predictor of aortic valvuloplasty outcome for fetal critical aortic stenosis and evolving HLHS

“…Image‐based, patient‐specific FE modelling of fetal LV myocardial biomechanics was performed in accordance with our previous methodologies (Green et al., 2022; Ong et al., 2020). The FE model was connected to a lumped parameter model to enable ventricular–vascular coupling.…”

“…The lumped parameter model was based on Pennati et al.’s work (Pennati et al., 1997; Pennati. & Fumero., 2000), but underwent minor recalibration to more recent measurements of human fetal intracardiac pressure (Johnson et al., 2000), and descending aorta pulse pressure (Versmold et al., 1981), as explained in our previous modelling study (Green et al., 2022), where all model parameters are given. The model is scalable to a range of gestational ages, through a series of allometric equations.…”

Advanced Techniques in Dynamic Cardiac Ultrasound Imaging for Assessing Left Ventricular Function in Heart Failure Patients

“…Heart failure is a severe clinical condition involving a decline in cardiac pumping capability, affecting systemic blood circulation [1][2][3]. Dynamic cardiac ultrasound imaging, a non-invasive and cost-effective diagnostic method, can visually display the cardiac motion state and is valuable for assessing left ventricular function [4,5]. However, traditional cardiac ultrasound images often face limitations in resolution and capturing dynamic details due to equipment and technological constraints, necessitating advanced image processing technologies to enhance diagnostic accuracy and efficiency.…”