The Cardiolock Project: Design of an Active Stabilizer for Cardiac Surgery

Coronary artery bypass grafting is a common surgical procedure that requires a high level of accuracy. To perform this procedure on a beating heart, surgeons reduce the heart motion with passive stabilizers. These devices, however, lack accuracy. Indeed, marked residual motion of the area of interest can be observed. In this paper, we address the problem with the design of an active stabilizer, i.e., an active mechanism controlled to cancel any residual motion during the surgery. The design methodology is based on dynamic modeling of the stabilization task and an iterative design approach. In fact, Cardiolock 1, a prototype allowing partial compensation, has first been developed in order to refine the design requirements. Its design and evaluation are presented, before introducing Cardiolock 2, a device with full stabilization capabilities. It includes a remote center of motion and takes advantage of the vicinity of kinematic singularities to provide mechanical amplification. Numerical and experimental analyses of the device are introduced, illustrating the practical potential of the proposed design.