Inside the beating heart: an in vivo feasibility study on fusing pre- and intra-operative imaging for minimally invasive therapy

An interventional system for minimally invasive cardiac surgery was developed for therapy delivery inside the beating heart, in absence of direct vision. A system was developed to provide a virtual reality (VR) environment that integrates pre-operative imaging, real-time intra-operative guidance using 2D trans-esophageal ultrasound, and models of the surgical tools tracked using a magnetic tracking system. Detailed 3D dynamic cardiac models were synthesized from high-resolution pre-operative MR data and registered within the intra-operative imaging environment. The feature-based registration technique was employed to fuse pre- and intra-operative data during in vivo intracardiac procedures on porcine subjects. This method was found to be suitable for in vivo applications as it relies on easily identifiable landmarks, and hence, it ensures satisfactory alignment of pre- and intra-operative anatomy in the region of interest (4.8 mm RMS alignment accuracy) within the VR environment. Our initial experience in translating this work to guide intracardiac interventions, such as mitral valve implantation and atrial septal defect repair demonstrated feasibility of the methods. Surgical guidance in the absence of direct vision and with no exposure to ionizing radiation was achieved, so our virtual environment constitutes a feasible candidate for performing various off-pump intracardiac interventions.