Interference No. 104,290
terminal of a Bovie(D electrosurgical unit. We are in agreement
with Hansen that the current flow path from the electrodes to the
ground was directly from the liver tissue to the ground connec
tion across the surface of the tissue in contact with the ground
plate. EX-5153, 512. We are further in agreement that the
impedance drop in the system was merely across the tissue of
the explanted liver. Id.
It is our finding that in actual use with a live
patient, the rf circuit established by the electrosurgical
apparatus includes the targeted tissue in which the electrodes
are placed along with the mass (composed of organs, tissue,
and blood) between the targeted tissue and the ground pads or
electrodes placed on the exterior of the body of the patient.
EX-5153, T13. Thus, both the targeted tissue and the body mass
contribute to the total impedance of the rf circuit, with the
body mass typically contributing the major share. Id. Since the
body mass typically dissipates the majority of the power, to
disregard this mass in the tests seriously underestimates the
amount of power needed to ablate tissue. Id. It is Hansen's
expert opinion that in the 1993 time frame one of ordinary skill
would not have known, absent in vivo testing or suitable modeling
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