Patent ID: 7142928

Claim:
A method of applying pacing pulses to cardiac tissue having a space constant to effect depolarization of a cardiac tissue mass of a heart chamber comprising; forming a discontinuity in the cardiac tissue of the heart chamber; disposing a pacing electrode supported by an electrode head at a distance exceeding the space constant of the cardiac tissue from the discontinuity in the cardiac tissue; and applying a stimulus to the cardiac tissue though the pacing electrode to form a depolarization region at the pacing electrode insufficient to propagate a depolarization wave front through the cardiac tissue mass of the heart chamber but sufficient to induce a transmembrane potential change at the tissue adjacent to the discontinuity that results in a propagated depolarization wave front to effect a contraction of the heart chamber, wherein the step of forming a discontinuity comprises forming an intracellular cleft by applying a cutting blade to the cardiac tissue to cut the cardiac tissue, wherein the cutting blade is supported to extend from the electrode head.