Unraveling the dynamics of pulsatile flow under pathophysiological conditions in curved tubules of kidney

Chronic kidney disease (CKD) is a critical global health challenge that requires a deeper understanding of kidney physiology and pathology to develop effective therapeutic strategies. This necessitates a thorough exploration of fluid dynamic interactions within the elastic kidney tubules. This study introduces a biomechanical model to investigate the dynamics of fluid flow in elastic kidney tubules while incorporating their physiological curvature characteristics. We present a numerical model to analyze pulsatile flow dynamics in the kidney tubules, incorporating curvature and compliance variations. A finite-element framework is used to evaluate flow parameters across varying wall stiffnesses, with validation against data from the literature. Our findings highlight that both curvature and tissue stiffness significantly impact fluid dynamics. Higher stiffness reduces peak axial velocity, while convex regions exhibit greater velocity and fluid shear stress (FSS) than concave regions. Relative to straight tubules, curvature leads to greater than an order of magnitude decrease in FSS, with concave regions producing the most pronounced suppression. Increased stiffness further decreases wall displacement, reduces von Mises stress, and lowers FSS due to reduced compliance. The relationship between stiffness and FSS suggests that mechanical forces within the tubule microenvironment are strongly influenced by tissue elasticity. As CKD progresses, renal tubules become stiffer, which alters these mechanical forces that further alter fluid dynamics, and contribute to the pathological conditions of the tubule structure. The complex interrelationships among kidney architecture, fluid structure interaction, and pathology highlight the therapeutic importance of taking curvature into account when figuring out how kidney disease progresses and creating tailored treatments.