Cardiolock: An Active Cardiac Stabilizer

Abstract

Abstract. Off-pump Coronary Artery Bypass Grafting (CABG) is still today a technically difficult procedure. In fact, the mechanical stabilizers used to locally suppress the heart excursion have been demonstrated to exhibit significant residual motion. We therefore propose a novel active stabilizer which is able to compensate for this residual motion. The interaction between the heart and a mechanical stabilizer is first assessed in vivo on an animal model. Then, the principle of active stabilization, based on the high speed vision-based control of a compliant mechanism, is presented. In vivo experimental results are given using a prototype which structure is compatible with a minimally invasive approach.

LWPR-model based predictive force control for serial comanipulation in beating heart surgery

“…In this case, contrarily to [4], the goal is not to stabilize the heart thanks to motion cancellation, but to apply a controlled force to the beating heart while following its motion. This idea was for example developed in [5] using ILC, which has the advantage of not requiring a model of the contact interaction but, again, exhibits low robustness to irregularities.…”

“…Two approaches are used for the rejection of the physiological motion disturbance: iterative learning control (ILC, [2]) which has the disadvantage of rejecting only strictly periodic disturbances, and Model-Based Predictive Control (MPC), which has proven to provide great robustness during in vivo experiments [1]. Note that position email:florez,morel@isir.upmc.fr MPC involving contacts between the robot and the heart has also been used for active stabilization in [4]. Here, the robot is in contact with the beating heart but the force in uncontrolled: rather, a visual servoing loop (i.e.…”

“…where control of the instrument is shared between the surgeon and the robot, recent work [7] has shown good force disturbance rejection and precision improvement for intracardiac beating heart applications. However, this approach uses a parametric simplified linear model of the organ-instrument interactions which is inappropiate.Indeed, as outlined in [4], considering a Mass-Spring-Damper as an approximation of cardiac muscle dynamics is somewhat inaccurate: the nonlinear time varying behavior of the stiffness, the mass and the damping parameters coming from electrical activity of the muscle, fluid motions and friction changes, are not taken into account. In the context of predictive control, these inaccuracies are expected to lead to poor performances.…”