This paper describes a two-dimensional cardiac propagation model based
on the finite volume method (FVM). This technique, originally derived
and applied within the field of computational fluid dynamics, is well
suited to the investigation of conduction in cardiac electrophysiolog
y. Specifically, the FVM permits the consideration of propagation in a
realistic structure, subject to arbitrary fiber orientations and regi
onally defined properties. In this application of the FVM, an arbitrar
ily shaped domain is decomposed into a set of constitutive quadrilater
als. Calculations are performed in a computational space, in which the
quadrilaterals are all represented simply as squares. Results are rel
ated to their physical-space equivalents by means of a transformation
matrix. The method is applied to a number of cases. First, large-scale
propagation is considered, in which a magnetic resonance-imaged cardi
ac cross-section serves as the governing geometry. Next, conduction is
examined in the presence of an isthmus formed by the microvasculature
in a slice of papillary muscle tissue. Under ischemic conditions, the
safety factor for propagation is seen to be related to orientation of
the fibers within the isthmus. Finally, conduction is studied in the
presence of an inexcitable obstacle and a curved fiber field. This exa
mple illustrates the dramatic influence of the complex orientation of
the fibers on the resulting activation pattern. The FVM provides a mea
ns of accurately modeling the cardiac structure and can help bridge th
e gap between computation and experiment in cardiac electrophysiology.