Preclinical Experience Using 4D Intracardiac Echocardiography to Guide Cardiac Electrophysiology Procedures.

introductionIntracardiac echocardiography (ICE) is an essential imaging modality for electrophysiology procedures, allowing intraprocedural monitoring, real-time catheter manipulation guidance, and visualization of complex anatomic structures. Four-dimentional (4D) ICE is the next stage in the evolution of the technology, permitting 360° rotation of the imaging plane, simultaneous multiplanar imaging, and volumetric acquisition, similar to transesophageal echocardiography (TEE). In this study, we report our experience with a novel 4D ICE catheter (NuVision, Biosense Webster) in structural electrophysiology procedures and difficult ventricular ablations in a swine preclinical model.

methods7 Yorkshire swine underwent 4D ICE (NuVision, Biosense Webster) imaging procedures and anatomical shells of the RV, LV, and LA were created on the CARTO mapping system. Ablation was performed on the RV moderator band and LV papillary muscles under imaging guidance with the 4D ICE catheter. Additional ICE images were obtained of the LAA to simulate placement of a left atrial appendage occlusion (LAAO) device. Triphenyl tetrazolium chloride was administered before euthanasia and hearts were harvested, fixed in formalin, and sectioned.

resultsCARTOSOUND reconstruction was completed using the novel multiplane imaging software platform, allowing for creation of anatomy with minimal movement of the ICE catheter. Maps generated were similar to 3D reconstruction acquired in pre-procedure CT. Ablation lesions were successfully delivered to the LV papillary muscles and RV moderator band with excellent correlation between gross pathology, electroanatomic mapping (EAM), and ICE images. 2D, multiplane, and 3D volumetric images were obtained of the LAA with minimal catheter movement to simulate use for an LAAO procedure. DISCUSSION: Intracardiac ultrasound has become an essential tool in the electrophysiology lab, especially for visualization of intracardiac structures in real time. 4D ICE is the natural progression of this technology, adding features previously only seen on TEE probes. In this preclinical study, 4D ICE was used to create CARTOSOUND shells with less catheter manipulation, which could decease procedural times and potentially decrease complications related to frequent manipulation of the ICE catheter. It was also placed in the left atrium to acquire multiplane and 3D rendered volumes of the left atrial appendage (LAA) similar to what would be required for an LAA occlusion procedure. This could be used as an alternative to TEE in LAAO procedures, potentially improving procedural efficiency and negating the need for general anesthesia. Additionally, it was used for real-time ablation guidance, specifically directly on the RV moderator band and LV papillary muscles. Multiplanar imaging allowed for more accurate catheter visualization and localization when targeting these complex 3D intracavitary structures.

conclusion4D ICE is the next stage in evolution of an essential imaging modality for electrophysiology procedures. Integration within the electroanatomical mapping system software platform may provide additional value for guiding ablation of challenging intracavitary structures and is a novel feature of the NuVision catheter. Through promising, this technology is new and further clinical investigation will be required to determine the ideal applications for its use.