An Experimental Determination of a Multipole Representation of a Turtle Heart

The potentials generated by a live turtle (pseudemys) heart at the center of a spherical electrolytic tank were measured at surface points. Using a truncated multipole expansion, the dipole and quadrupole coefficients were determined from the resultant set of simultaneous equations at intervals over the QRS period. The measurement technique was checked using known artificial sources; a rough check on the truncation assumptions was made based on a known analytical model. The experimental results show that a significant quadrupole term is present. The presence of higher order poles could not be ruled out.