Photoacoustic guidance of RF ablation for atrial fibrillation
Atrial Fibrillation (AF) is the most common heart rhythm disorder, affecting about 7 million people in Europe and the US. Treatment for AF aims to restore the normal sinus rhythm or to control the ventricular rate through pharmacologic therapy or cardioversion, If these are not successful (>50% of patients), radiofrequency catheter ablation (RFA) of the atrial wall tissue can intersect the erratic current loops supporting the fibrillation waves. Any remaining conductivity, or restoration of conductivity after the procedure, will render the intervention unsuccessful. Excessive ablation, on the other hand, leads to mechanical failure and possibly perforation of the atrial wall. The former severely degrades cardiac function, while the latter is a life-threatening complication during the procedure. A real-time monitoring tool for intraprocedural assessment of lesion depth, extent and functionality could significantly increase the success rate and limit major complications of RFA.
In this project we devise a new device and method for monitoring of RFA during the procedure. We add functional lesion information to the structural ICE/TEE image by outfitting the ablation catheter with an optical delivery channel for volumetric photoacoustic (PA) imaging. The device is fully integrated with the RFA workflow under intracardiac echography (ICE) or transesophageal echo (TEE) guidance. RFA creates a thermal lesion in the atrial wall, with clearly recognizable optical and structural changes to the tissue. This can be detected by PA imaging, and used for monitoring of lesion depth, lesion functionality, and limiting excessive ablation. The PA signal from the tissue surface serves the additional function of accurate navigation and localization of the ablation device
WP2.1.1. Photoacoustic guidance of RF ablation for atrial fibrillation (Erasmus MC)
Based on a series of in vitro experiments, we investigate the relation between the PA image of the ablated site and effectiveness of the intervention. PA imaging targets are lesion extent in 2D or 3D, and lesion conductivity. These experiments generate the knowledge to decide when to stop ablating, not too early but importantly also not too late. These experiments are performed on porcine atrial tissue, initially in saline but as soon as possible in a heparinized blood environment, in realistic ablation protocols, with and without saline irrigation. The project moves from basic characterization of healthy and ablated tissues, through the development of an integrated ablation/imaging (PA-RFA) catheter and system, to a PA guided protocol for intra-atrial interventions. If successful, we test this protocol in vivo in an animal setting.