Bio-battery signal predicts myocardial lesion formation and depth in vitro

Aims: The aim of this study was to determine if the bio-battery signal can predict myocardial lesion formation and depth. Methods: Fresh bovine ventri cular myocardium was immersed in a temperature-controlled bath of circulati ng blood. RF energy was delivered with a custom generator to a catheter ele ctrode. RF energy, electrode temperature, bio-battery signal and tissue imp edance were displayed and recorded. A copper return plate was placed in the bath. Results: When 50 volts of constant RF energy was terminated at a 20, 40, or 60% decline from the maximum bio-battery signal, the lesion depth w as 4+/-0.4 mm. When RF energy application was terminated later, at a point characterized by a brief change of slope of the bio-battery signal, the les ions measured 7.8+/-1.4 mm in depth. This "bump" occurred before a rapid im pedance rise. Conclusion: The depth of lesions created at the "bump" point was almost two-fold deeper than those at the termination points of 20, 40 a nd 60% bio-battery decrease (p = 0.0001). When RF energy was terminated at the rapid impedance rise the lesions were similar in depth, 8.2+/-0.9 mm, t o those obtained when RF energy was stopped at the "bump" (p = 0.28). The b io-battery signal provides a unique marker that might be useful to obtain m aximum lesion depth while avoiding rapid impedance rise.