Qa. Ni et al., Three-dimensional activation mapping in ventricular muscle: Interpolation and approximation of activation times, ANN BIOMED, 27(5), 1999, pp. 617-626
Interpolation plays an important role in analyzing or visualizing any scala
r field because it provides a means to estimate field values between measur
ed sites. A specific example is the measurement of the electrical activity
of the heart, either on its surface or within the muscle, a technique known
as cardiac mapping, which is widely used in research. While three-dimensio
nal measurement of cardiac fields by means of multielectrode needles is rel
atively common, the interpolation methods used to analyze these measurement
s have rarely been studied systematically. The present study addressed this
need by applying three trivariate techniques to cardiac mapping and evalua
ting their accuracy in estimating activation times at unmeasured locations.
The techniques were tetrahedron-based linear interpolation, Hardy's interp
olation, and least-square quadratic approximation. The test conditions incl
uded activation times from both high-resolution simulations and measurement
s from canine experiments. All three techniques performed satisfactorily at
measurement spacing less than or equal to 2 mm. At the larger inter-electr
ode spacings typical in cardiac mapping (1 cm), Hardy's interpolation prove
d superior both in terms of statistical measures and qualitative reconstruc
tion of field details. This paper provides extensive comparisons among the
methods and descriptions of expected errors for each method at a variety of
sampling intervals and conditions. (C) 1999 Biomedical Engineering Society
. [S0090-6964(99)01105-4].