The Effects of Spatial and Temporal Properties on a Viscoelastic Model of the Dyssynchronous Canine Heart
Abstract
In this study, lumped parameter cardiovascular modeling has been used to understand
the influence of muscle properties on mechanical dyssynchrony (MD) as well as general
muscle dynamics. Incorporating viscous influence into the model allowed for an expanded
view when analyzing muscle parameter response to MD. A unique method of ventricle
segmentation was introduced that allowed fast analysis of regional and global ventricular
properties. This segmentation process produced a ventricle with four identical sections
each consisting of separately tunable muscle properties in the form of minimum and
maximum elastance, elastance waveform delay, and myocardial viscous friction, yet these
regional sections remained globally dependent. Elastance waveform delay proved to be
the most influential property on MD as measured by internal flow fraction (IFF), followed
by regional elastance magnitude, and finally regional viscosity influence. Due to the
unique segmentation of this model, two metrics for IFF were derived: (1) the "true" IFF
(IFF-4seg) and (2) the IFF as would be measured by an ideal conductance catheter (IFF-CC).
The results of IFF-CC versus IFF-4seg show that conductance catheters are not capable of
measuring IFF during a side-to-side volume transfer within the stacked cylinder under
measurement. Finally, unique energetic situations were observed with this model that
point to likely myocardium remodeling situations.