Chronic phase problems cardiomyoplasty were examined using 7 canine models. We have transferred a latissimus dorsi muscle flap to the heart through the second intercostal space and subsequently wrapped around both ventricles in a counterclockwise manner. After 2-4 months electrical conditioning, change of hemodynamics with latissimus dorsi stimulation were examined in varying muscle stimulation parameters. As a stimulating generator we used ambulatory extracorporeal burst-pulse generator (Juntendo type, model MC 4102) which we have developed. Ventricular pressure increasing was more significant at right ventricle which has thinner wall. However, for left ventricular assist, we should increase higher voltage stimulation, which goes beyond physiologically normal range. Moreover, impedance between stimulating leads steadily increased. It is suggested that special modification in pacing wire leads is needed.