Novel Spherical Ultrasonic Array Mounted on Intra-Cardial Catheter for Left Atrium Surface Reconstruction

Background Cardiac arrhythmia is the clinical term for the set of diseases wherein the heart beats irregularly. Of these conditions, atrial fibrillation(AF) is one of the most prevalent and affects about 25 percent of the population of European descent after the age of 40. This condition increases the risk of stroke five fold, impacts quality of life, causes hundreds of thousands hospitalizations in the US and is linked with increased mortality. Electrical pulmonary vein isolation (PVI) from the left atria (LA) body is performed using ablation for treating AF. This and many others minimally invasive catheterization, require real-time visualization and tracking of the LA surface.

Methods We propose a novel catheter incorporating ultrasound transducers on a set of splines, and an algorithm capable of real time detection of the blood tissue and (heart) chamber boundary, with no or little need for catheter movement or rotation. Unlike traditional ultrasound arrays, this catheter has small number of transducers far below Nyquist criteria with a spherical field of view, for which very little theoretical and practical guarantees are known. We use a non-linear minimum filter to observe the blood pool location in space and compare it with reflecting tissue producing high contrast images of the boundary. A prototype containing 64 elements over PCB splines was built alongside with ellipsoidal and LA laboratory phantoms.

Results Simulation and phantom studies shows reconstruction of the ellipsoid shape and LA body.

Conclusion experiments indicate that the detection and tracking of the LA boundary using this system is feasible.