Cardiac pacing effects on the electrical conduction in isolated rabbit hearts

This study presents the effects of cardiac pacing using stimulation pulses of different polarities (anodal, cathodal), strengths and waveshapes (monophasic and biphasic) on the electrical conduction in Langendorff perfused rabbit hearts. We have measured the conduction velocities in the longitudinal and transverse directions to the fiber orientation using bipolar electrograms from 12 epicardial sites. The transmembrane potential changes and the maximum rate of AP upstroke, ((dV/dt)/sub max/) under these stimulation conditions are measured using floating tip microelectrodes. The results show a superior performance of biphasic and anodal monophasic pulses that could suggest a novel way to improve myocardial conduction.