A real-time system for prosthetic valve tracking

Transcatheter aortic valve replacement is a minimally invasive technique for the treatment of valvular heart disease, where an artificial valve mounted on a balloon catheter is guided to the aortic valve annulus. The balloon catheter is then expanded and displaces the diseased valve. We recently proposed an algorithm to track the 3D position, orientation and shape of a prosthetic transcatheter aortic valve using biplane fluoroscopic imaging. In this work, we present a real time hardware and software implementation of this prosthetic valve tracking method. A prototype was implemented which gathers fluoroscopic images from the angiography system via a research interface. A dynamic point cloud model of the valve is then used to estimate the 3D position, orientation and shape by minimizing a cost function. The cost function is implemented using parallel processing on graphics processing units to improve the performance. The system includes 3D rendering of the valve model and additional anatomy for visualization. The timing performance of the system was evaluated using a plastic cylinder phantom and a prosthetic valve mounted on a balloon catheter. The total computation time per frame for tracking and visualization using two different valve models was 46.11 ms and 43.88 ms respectively. This would allow frame rates of up to 21.69 frames per second. The target registration error of the estimated valve model was 1.22 ± 0.29 mm. Combined with 3D echocardiographic imaging, this technique would enable real time image guidance in 3D, where both the prosthetic valve and the soft tissue of the heart are visible.