Design and Control of Motion Compensation Cardiac Catheters

Robotic cardiac catheters have the potential to revolutionize heart surgery by extending minimally invasive techniques to complex surgical repairs inside the heart. However, catheter technologies are currently unable to track fast tissue motion, which is required to perform delicate procedures inside a beating heart. This paper proposes an actuated catheter tool that compensated for the motion of heart structures like the mitral valve apparatus by servoing a catheter guidewire inside a flexible sheath. We examine design and operation parameters that affect performance and establish that friction and backlash limit the tracking performance of the catheter system. Based on the results of these experiments and a model of the backlash behavior, we propose and implement compensation methods to improve trajectory tracking performance. The catheter system is evaluated with 3D ultrasound guidance in simulate in vivo conditions. the results demonstrate that with mechanical and control system design improvements, a robotic catheter system can accurately track the fast motion of the human mitral valve.Engineering and Applied Science

A truncation error model and its application to the accuracy analysis of constraint violations

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77162/1/AIAA-1993-3707-458.pd

Ultrasound Servoing of Catheters for Beating Heart Valve Repair

Robotic cardiac catheters have the potential to revolutionize heart surgery by extending minimally invasive techniques to complex surgical repairs inside the heart. However, catheter technologies are currently unable to track fast tissue motion, which is required to perform delicate procedures inside a beating heart. This paper presents an actuated catheter tool that compensates for the motion of heart structures like the mitral valve apparatus by servoing a catheter guidewire inside a flexible sheath. We examine design and operation parameters and establish that friction and backlash limit the tracking performance of the catheter system. Based on the results of these experiments, we implement compensation methods to improve trajectory tracking. The catheter system is then integrated with an ultrasound-based visual servoing system to enable fast tissue tracking. In vivo tests show RMS tracking errors of 0.77 mm for following the porcine mitral valve annulus trajectory. The results demonstrate that an ultrasound-guided robotic catheter system can accurately track the fast motion of the mitral valve.Engineering and Applied Science

Haptic Noise Cancellation: Restoring Force Perception in Robotically-Assisted Beating Heart Surgery

Beating heart surgical methods have the potential to remove the need for the heart-lung machine and its attendant side effects, but must contend with the motion of the heart. Recent research in robotically-assisted surgery has produced a handheld, actuated in- strument that can track and compensate for heart motion; however, the reaction forces caused by the actuation mechanism make it dif- ficult for the surgeon to feel the heart during the operation, which can lead to unsafe tissue manipulation. This paper investigates an instrument design that negates reaction forces to the user by moving a counterweight out of phase with the moving mass of the actuator. The resulting instrument retains the tracking and motion compensa- tion abilities of the current instrument, but reduces reaction forces felt by the user by over 80%. Subjects used the new instrument in an in vitro beating heart surgical contact task and performance was compared to the previously existing instrument. The new in- strument provided a 28% increase in user force sensitivity and im- proved user reaction times by 51%, indicating that the new instru- ment greatly enhances force perception in beating heart tasks.Engineering and Applied Science

Fiber Optic Projection-Imaging System for Shape Measurement in Confined Space

A fiber-based projection-imaging system is proposed for shape measurement in confined space. Owing to the flexibility of imaging fibers, the system can be used in special scenarios that are difficult for conventional experimental setups. Three experiments: open space, closed space, and underwater are designed to demonstrate the strength and weakness of the system. It is shown that when proper alignment is possible, relatively high accuracy can be achieved; the error is less than 2% of the overall height of a specimen. In situations where alignment is difficult, significantly increased error is observed. The error is in the form of gross-scale geometrical distortion; for example, flat surface is reconstructed with curvature. In addition, the imaging fibers may introduce fine-scale noise into phase measurement, which has to be suppressed by smoothing filters. Based on results and analysis, it is found that although a fiber-based system has its unique strength, existing calibration and processing methods for fringe patterns have to be modified to overcome its drawbacks so as to accommodate wider applications

Real-Time 4D Ultrasound Mosaicing and Visualization

Intra-cardiac 3D ultrasound imaging has enabled new minimally invasive procedures. Its narrow field of view, however, limits its efficacy in guiding beating heart procedures where geometrically complex and spatially extended moving anatomic structures are often involved. In this paper, we present a system that performs electrocardiograph gated 4D mosaicing and visualization of 3DUS volumes. Real-time operation is enabled by GPU implementation. The method is validated on phantom and porcine heart data.Engineering and Applied Science