Surgical devices for stabilizing the heart are disclosed which facilitate anastomosis under beating heart conditions. Various instruments or devices may be maneuvered and secured on a retractor device to provide stabilization of the heart. An instrument mount is provided which is preferably configured to accept a surgical instrument, such as a tissue stabilizer, and to allow the instrument to be easily maneuvered to a desired position and subsequently locked into position with a simple operation of a single locking actuator. Further disclosed are stabilizer devices each having at least one surface for contacting the heart and each being adapted to be mounted to the retractor while having the ability to be positioned in the desired location against the heart.