Right Heart Assist by Pedicle Skeletal Muscle - An Application for Fontan's Operation

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This study was conducted to investigate the effect of right heart assist by pedicle skeletal muscle on the hemodynamics after Fontan's operation in order to extend its operative indication. Experimental Fontan's operation model in which experimental animals could survive for long term periods was established. In comparison of the hemodynamic data between normal and Fontan's circulations, systemic blood pressure and cardiac output in Fontan's circulation decreased to 50-70% and 30-50% of the levels in normal circulation, respectively. On the other hand, pulmonary vascular resistance increased to 2.6 times normal level after Fontan's operation. It was recognized that skeletal muscle sutured to either the right atrium or right ventricle acted as a right heart assist device when it was stimulated by burst impulse, but it was easy to fatigue during continuous stimulation. After Fontan's operation, the latissimus dorsi muscle wrapping around the left and right ventricles was stimulated by burst impulse. This muscle stimulation caused an increase of blood pressure and cardiac output to 130 and 170% of the values before stimulation, respectively. Pulmonary vascular resistance was reduced to 40% of the Fontan's circulation level.From these results it was concluded that right heart assist by electrical stimulation of pedicle skeletal muscle implanted around the heart improved hemodynamics after Fontan's operation. Further study is necessary to define adequate implantation portion of the skeletal muscle and better stimulation mode, and to make fatigue resistant muscle in order to have more effective right heart assist.