Integrating mapping and 4D ultrasound – is this the dawn of a new ICE age?Rachel M. Kaplan, MD, MS, FHRSIntracardiac echocardiography (ICE) is routinely used by electrophysiologists in the United States for numerous procedures. ICE provides visualization of anatomic structures and can be used to guide ablation lesions. Integration with mapping expands the utility of ICE to also facilitate acquisition of anatomic geometry and aid in identifying structures of interest such as coronary arteries.In the past few years, multiple companies have developed 4D ICE catheters which have elevated the range of imaging obtainable with ICE to be more similar to modern transesophageal echocardiography (TEE). These catheters can obtain multiplanar imaging which enables 3D views in real time and can reduce the need for ICE catheter manipulation to obtain multiple views1.The use of 4D ICE is increasingly described for LAAO, primarily because it can substitute for TEE. Multiple studies have shown comparable outcomes between ICE guided and TEE guided LAAO, though some have shown higher rates of pericardial effusions with ICE2-4. Reduced need for catheter manipulation in the left atrium with 4D ICE catheters may help mitigate this risk. The benefit of utilizing 4D ICE in ablation procedures is less clear. Beyond the technologic intrigue, multiplanar and 3D imaging is not typically required in ablations5. However, integration with mapping has the potential to utilize these additional imaging features for benefit in ablation procedures.In this issue of JCE, Blumenthal et al . describe a pre-clinical study of the use of a 4D ICE catheter with mapping integration in swine models6. The NuVision 4D ICE catheter (Biosense Webster) provides real-time 3D ultrasound imaging and integrates with CARTO anatomic mapping (CARTOSOUND, Biosense Webster). They demonstrated rapid acquisition of geometry by using CARTOSOUND with the 4D ICE catheter where multiplane imaging acquires two 2D images with each position. Furthermore, 360-degree imaging can be obtained without moving the catheter itself. Additionally, ICE provides real time visualization during cardiac motion which can show the operator how the ablation catheter is moving on a structure such as the papillary muscles, therefore improving catheter stability.There are a few drawbacks to 4D ICE. The catheters are slightly larger which then require larger bore vascular access and higher risk of vascular complications. The biggest concern, however, is cost. These catheters cost significantly more than standard 2D ICE catheters. Cost-effectiveness of 2D ICE has been described for LAAO procedures where it has been shown to be comparable to TEE for overall costs (counting both equipment and professional services)7. However, studies comparing 4D to 2D ICE for LAAO have shown that the 3D images are more comparable to TEE with regards to sizing of the LAAO device8. Demonstrating cost-effectiveness of 4D ICE for ablation procedures will be more complex. Future studies will need to investigate effects on procedure duration, risk of complications, or even procedure efficacy (perhaps for papillary muscle premature ventricular contractions where stability can be difficult). Unfortunately, until cost effectiveness demonstrates tangible benefits to 4D ICE in ablations, these catheters may be relegated to selective and investigational use in most hospitals.One niche area for a mapping-integrated 4D ICE catheter may be concomitant atrial fibrillation ablation with LAAO because ICE is typically used in the United States for atrial fibrillation ablation. Use of 4D ICE can enable the entire case to be performed without needing to use TEE for the LAAO part. This also avoids the requirement for a TEE trained imaging physician to be available for the procedure. An example of an LAAO device implant under 4D ICE guidance with the NuVision catheter is shown in the Figure. In this case, the patient underwent pulmonary vein isolation with the ICE catheter in the right atrium, then the NuVision ICE was advanced into the left atrium to guide the implantation of a Watchman device (Boston Scientific). In such cases, the added cost of a 4D ICE catheter compared to a 2D ICE catheter can be offset by not needing the expense of TEE or TEE trained physicians. Imaging with 4D ICE catheters requires advanced knowledge of the imaging console which is often provided by representatives from the ICE catheter company. However, such costs are borne by the whole healthcare industry rather than attributed to an individual procedure by the hospital.Mapping integrated 4D ICE is a technologically exciting forward step though its utility in ablation procedures has yet to be established. Cost concerns will likely limit its broad adoption but it may provide benefits in specific complex ablation cases or perhaps in concomitant ablations with LAAO.1. Adams A, Mahmood R, Balaji N, Dixit P, Chandra S, Weisman D. Real-world experience utilizing the nuvision 4D intracardiac echocardiography catheter for left atrial appendage closure. Sci Rep. 2024;14(1):11937.2. Ferro EG, Alkhouli M, Nair DG, et al. Intracardiac vs Transesophageal Echocardiography for Left Atrial Appendage Occlusion With Watchman FLX in the U.S. JACC Clin Electrophysiol. 2023;9(12):2587-2599.3. Serpa F, Rivera A, Fernandes JM, et al. Intracardiac vs transesophageal echocardiography for left atrial appendage occlusion: An updated systematic review and meta-analysis. Heart Rhythm. 2024.4. Diaz JC, Bastidas O, Duque M, et al. Impact of intracardiac echocardiography versus transesophageal echocardiography guidance on left atrial appendage occlusion procedures: A meta-analysis. J Cardiovasc Electrophysiol. 2024;35(1):44-57.5. Kaplan RM, Narang A, Gay H, et al. Use of a novel 4D intracardiac echocardiography catheter to guide interventional electrophysiology procedures. J Cardiovasc Electrophysiol. 2021;32(12):3117-3124.6. Blumenthal C, Hsue W, Chen T, Zhang D, Brem E, Garcia F, Callans DJ, Marchlinski FE, Santageli P, Tschabrunn CM. Pre-Clinical Experience using 4D ICE to Guide Ablation and Structural Procedures of Complex Intracavitary Structures. Journal of Cardiovascular Electrophysiology. 2024.7. Alkhouli M, Chaker Z, Alqahtani F, Raslan S, Raybuck B. Outcomes of Routine Intracardiac Echocardiography to Guide Left Atrial Appendage Occlusion. JACC Clin Electrophysiol. 2020;6(4):393-400.8. Della Rocca DG, Magnocavallo M, Gianni C, et al. Three-dimensional intracardiac echocardiography for left atrial appendage sizing and percutaneous occlusion guidance. Europace. 2023;26(1).Figure
