Control for Robot-assisted Image-guided Beating-heart Surgery

• Author / Creator

  Bowthorpe, Meaghan L

• Cardiovascular disease causes the greatest number of deaths worldwide each year according to the World Health Organization [1]. Hence, many patients require cardiovascular surgery each year. Short of stopping the motion of the heart at the beginning of a cardiac procedure, the surgeon would require superhuman ability to both follow the heart's beating motion and perform surgical maneuvers on the exterior surface of the heart. Performing a surgical procedure within the interior of a beating heart would be even more difficult due to the opaque blood pool that makes it difficult to visualize the heart tissue. Currently, to overcome the aforementioned obstacles, surgeons operate on either a mechanically stabilized or arrested heart, where a heart-lung machine ventilates the lungs and circulates the blood. A mechanical heart stabilizer can only minimize motion in a localized area on the exterior surface of the heart; it cannot completely stop the motion. Arresting the heart can lead to long-term cognitive loss [2], an increase in the risk of stroke [3], and complications when the heart is restarted. Alternatively, a robot-held surgical tool can be controlled to follow the motion of a point of interest (POI) on the heart, allowing the heart to beat freely throughout the procedure. This would reduce the risks currently involved in mechanically stabilized and arrested heart surgery. In this scenario, the surgeon's hand motion is superimposed on the synchronizing movement of the robot. In this way, with a stabilized view of the heart, the point of interest on the heart appears stationary to the surgeon with respect to the surgical tool's tip. Allowing the heart to beat freely during the procedure means that the surgeon will be able to immediately evaluate the success of reconstructive operations and make adjustments as required. In contrast, using the current practice of arresting the heart at the outset of surgery, the outcome of the procedure is not known until after restarting the heart, and the surgeon would have to once again connect the patient to a heart-lung machine should additional operations be required. This thesis presents the development of an experimental robot-assisted beating-heart surgical setup for procedures performed on either the exterior surface or interior of the heart. As the system must be able to visualize through the heart's blood pool in order for procedures to be performed inside the heart, ultrasound-guidance is considered. The challenge with using ultrasound images to locate the point of interest on the heart is that the position data is slowly sampled and delayed due to the time required to acquire and process each image. Therefore, in order for the surgical robot to provide good tracking, the motion of the point of interest on the heart measured from the ultrasound images must be upsampled and predicted ahead to the current time. This thesis presents different upsampling and prediction methods as well as different control structures for this purpose. The image processing required to locate the surgical tool and the point of interest on the heart tissue in ultrasound images is also discussed. The controllers have been validated experimentally and user trials were performed to determine whether such a system would, in fact, help surgeons.

• Subjects / Keywords

  • Beating-heart Surgery
  • Controls

• Graduation date

  Spring 2016

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R39W09B4R

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.