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Fixing the Beating Heart:
Ultrasound Guidance for Robotic Intracardiac Surgery
Robert Howe
Harvard University

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Ultrasound Guidance for Robotic Intracardiac Surgery

To treat defects within the heart, surgeons currently use stopped-heart techniques. These procedures are highly invasive and incur a significant risk of neurological impairment. We are developing methods for performing surgery within the heart while it is beating. New real-time 3-D ultrasound imaging allows visualization through the opaque blood pool, but this imaging modality poses difficult image processing challenges, including poor resolution, acoustic artifacts, and data rates of 30 to 40 million voxels per second. To track instruments within the heart we have developed a Radon transform-based algorithm, which is readily implemented in real-time on graphics processor units. For manipulation of rapidly moving cardiac tissue we have created a fast robotic device that can track the tissue based on ultrasound image features. This allows the surgeon to interact with the heart as if it was stationary. To integrate ultrasound imaging with the robotic device we have developed a predictive controller that compensates for the 50-100 ms imaging and image processing delays to ensure good tracking performance. In vivo studies show that this approach enhances dexterity and听 lowers applied forces. Clinical applications of this technology include atrial septal defect closure and mitral valve annuloplasty.