Biomechanics of Early Cardiac Development: A Nonlinear Explicit FE Model of C-Looping in the Embryonic Chick Heart

C-looping is the morphomechanical process through which the initially straight embryonic heart tube (HT) reconfigures into a doubly bent, twisted, swollen, c-shaped tube [1] between stages HH10⁻ and HH12 [2]. According to the biomechanical hypotheses proposed by Taber [3], the ventral and rightward bending of the heart tube are intrinsic to the initially straight HT, and are caused by actin polymerization within myocardial cells. The torsion and rotation of the HT are due to a rightward oriented force generated by the elongation of the left omphalomesenteric vein (OV) and a dorsally oriented force due to tension in the splanchnopleure (SPL) [4]. In order to numerically test these biomechanical hypotheses, the standard stiffness-based nonlinear finite element formulation (standard FE) has been modified to include growth-based deformation to simulate c-looping [5]. However, due to numerical difficulties, such an approach can represent only the initial stages of c-looping and does not include SPL contact, or the merger (fusion) of the OV, which contributes to the elongation of the caudal heart tube [6]. To overcome these modeling difficulties, we propose the use of the explicit finite element formulation (explicit FE) as an alternative technique for modeling c-looping.