Page 171 - Computational Modeling in Biomedical Engineering and Medical Physics

160 Computational Modeling in Biomedical Engineering and Medical Physics

Figure 5.10 Electric potential, through surface gray map, and electric current flow through streamline
tubes (left); electric current density, through streamlines, and the blood flow, through arrows (right).

Figure 5.11 (Left) Z(t) and dZ/dt. (Middle) Z(t) for the DC model—normalized w.r.t. its peak value.
(Right) Time derivatives of the DC and AC impedances, normalized.

Moreover, several subtle details are also evidenced, for example, the emergence
of the A-wave (Fig. 5.11C) that confirms the cardiac flow specificity stemmed
through the velocity profile, which is used as inlet condition. The role of the atria
dynamics in the A-wave is still to clarify. The A-wave appears to be associated to
their contraction, although several studies indicate that the wave of blood reflected
from the atria to the central veins might produce it. The ejection in the left atrium
could be one major source of the reflected wave, hence the pending ejection portion
is cogently related to the A-wave magnitude (Taylor et al., 1998).
The AC and DC models outcome resembles Z(t)and dZ(t)/dt profiles (Fig. 5.11C)
anditisexpectedtoproduce similarcardiovascularindices.Itmay be inferred that,