Conceptual modeling of cardiovascular sounds.

In this paper, it is shown that the main source of mechanical energy of cardiovascular (CV) system i.e., rhythmic heart contraction is transformed to the oscillations of the CV walls and blood flow, and finally CV acoustical waves. These waves propagate through both blood flow (hemodynamical pathways) and tissues (viscoelastical pathways) toward the skin. Nonetheless, the CV walls could be assumed as the source of acoustical waves, since they act as the interface between blood flows and other tissues including skin. After obtaining the approximate accelerations of CV walls from pressure-flow (PF) models, we also needed to model the viscoelastical pathways until the skin. Some improvements on PF models were fulfilled to present small variations of blood pressure such as dicrotic notch. The turbulence occurrence was also noticed to and conceptually modeled. The total homomorphic model could conceptually show the relations of CV sounds with CV characterizations and tissue specifications. Thus, it could be helpful to assess CV system in order to diagnose CV diseases via CV sounds. The CV sounds recorded from the skin of any place (e.g., chest or arm) could be simulated via this model, if the hemodynamical and viscoelastical parameters especially for the region under that place are obtained.