Effect of lateral vibrations on hemodynamics of blood flow in patient-specific forearm and hand arterial system

Abstract

Exposure to external vibration almost immediately reduces blood flow in human fingers. Repeated exposure can lead to stenosis and permanent blood flow reduction, resulting in a condition known as vibration white finger. Although this phenomenon is well-established, the underlying mechanisms remain unclear. Notably, vibration does not similarly affect flow in inert tubes. We hypothesize that vibration disrupts the normal feedback between vessel wall tension and local blood flow, consequently impairing healthy blood distribution. This hypothesis suggests a fundamental biomechanical cause for the phenomenon, complementing existing research on nerve damage and vessel wall deterioration. By examining different vibrational frequencies and accelerations of vibration, this research aims to identify the changes on hemodynamic parameters of blood flow under lateral vibration with a specific insight to wall shear stress (WSS) parameter. The extent to which humans are adversely affected by vibration will be assessed using models that closely resemble real arteries based on our patient-specific 3D model. The flow path includes the brachial artery, which bifurcates into the radial and ulnar arteries. The ulnar artery further bifurcates into the digital arteries. Our investigation will employ computational fluid dynamics models of blood vessels, designed using CT-angiography images based on volunteer-specific data. These models will feature Generalized Power Law non-Newtonian blood model and Windkessel-type outlet conditions. The results indicate that lateral vibration induces fluctuation on the WSS pattern, with an observed increase in both amplitude and number of fluctuations as the acceleration of vibration rises. To our knowledge, for the first time the occurring of reflective wave is recognized. Beyond a certain threshold, reflective wave occurrence emerges, initiating from the terminal region of cardiac cycle and propagating as acceleration of vibration continues to increase. This propagation is associated with a corresponding rise in the number of fluctuations. Increasing the value of fluctuation amplitude and its quantity, overall, as the acceleration increases, and the occurrence of reflective wave further stimulates Pacinian corpuscle, amplifying its effects. As frequency of vibration increases, rise in fluctuations is observed undeniably, exacerbating destructive outcomes. When frequency of vibration surpasses a certain threshold, reflective wave occurrence also happens in this context; By raising the value of frequency, the phase alignment leads to also the superposition of the original wave and reflective wave. The occurring of reflective waves is also dependent on the geometry. The initiation of reflective predominantly occurs at junctions before transitioning to the simpler locations.

Keywords: Computational fluid dynamics; Hand-arm vibration syndrome; Lateral vibration; Muscular artery; Non-Newtonian blood model; Pulsatile flow; Wall shear stress; Windkessel model.