Active heart stabilization can help the development of less invasive surgical techniques in the cardiac field. The GyroLock device we propose insures this function using Control Moment Gyro (CMG) actuation, which avoids linkage to the environment. This system is completely independent and pluggable on commercial instruments. For control we use an adaptive algorithm featuring harmonic disturbance cancellation. The first in vivo experiments of the GyroLock using the adaptive control are presented and the results based on two sensor technologies are compared. They exhibit a displacement reduction of more than 90% for cardiac harmonics.