Congenital and Structural Heart Disease Interventions Using Echocardiography- Fluoroscopy Fusion Imaging Pei-Ni Jone, MD, Alexander Haak, PhD, Michael Ross, MD, Dominik M. Wiktor, MD, Edward Gill, MD, Robert A. Quaife, MD, John C. Messenger, MD, Ernesto E. Salcedo, MD, and John D. Carroll, MD, Aurora, Colorado, and Andover, Massachusetts With the increasing frequency of catheter-based interventions in congenital heart disease and structural heart disease, the use of fusion imaging has become a major enhancement for understanding complex anatomy and facilitating key steps in interventional procedures. Because transesophageal echocardiography and fluoros- copy are displayed in different visual perspectives, the interventional cardiologist must mentally reregister the images from the two modalities during the procedure. Echocardiography-fluoroscopy fusion (EFF) imaging displays the x-ray and ultrasound overlay images in the same visual perspective. This new technology allows for enhanced team communication, improved visual guidance, and more efficient navigation. The purpose of this review is to describe the EFF imaging technology, current uses of EFF imaging in congenital and structural heart disease, and future directions that will enhance this unique imaging technology to guide interventional procedures. (J Am Soc Echocardiogr 2019;-:---.) Keywords: Image-guided interventions, Echocardiography-fluoroscopy fusion imaging, Three-dimensional echocardiography, Congenital heart disease, Structural heart disease Catheter-based interventions in congenital and structural heart dis- ease continue to expand, and the image guidance of these procedures must be robust. The use of fusion imaging has become one major enhancement for the understanding of complex anatomy and facili- tating key steps in interventional procedures. Complex procedures or complicated anatomy may lead to increased radiation dose, contrast dye, and procedural time when only two-dimensional (2D) fluoroscopy is used. The fusion of intraprocedure fluoroscopy with preprocedural computed tomography/magnetic resonance imaging or intraprocedural three-dimensional (3D) rotational angiography is another approach that may aid in the characterization of the 3D anatomic details and may reduce radiation, contrast volume, and pro- cedural time. 1-3 However, the overlay of computed tomography/ magnetic resonance imaging and 3D rotational angiography provides static image integration without dynamic or real-time image fusion during the procedure. Fused echocardiography and x-ray fluo- roscopy provide real-time imaging that may facilitate procedural guid- ance. 1,4-14 X-ray fluoroscopy is ideally suited to visualize catheters and de- vices, whereas 2D or 3D transesophageal echocardiography (TEE) permits visualization of soft cardiac tissue and blood flow velocity information. However, these x-ray and ultrasound im- ages are typically displayed in different spatial frames of refer- ence. For example, fluoroscopy in the anterior-posterior projection is common, and TEE images are often presented with the perspective from the esophagus. As a result, there is a risk of miscommunication regarding anatomic orientation and undermining the hand-eye coordination needed to guide the intervention. The conventional spatial orientation of the two mo- dalities is also different: left on fluoroscopy might be right on echocardiography, and up on the echocardiographic image might be down on fluoroscopy. Each time the interventional cardiologist switches attention from fluoroscopy to echocardiography, he or she must mentally reorient and change hand-eye coordination. Without the assistance of fusion imaging, the interventional cardi- ologist and echocardiographer attempt to integrate image orien- tation, target location, and trajectory through a complex communication dialogue during the intervention. Contemporary structural and congenital heart disease (CHD) in- terventions demand sophisticated intraprocedural imaging and optimization of imaging display. Currently, several companies have developed or are in the process of developing image fusion technology for the growing number and diversity of interventional applications requiring guidance by both x-ray and ultrasound imaging modalities. 9-11 Echocardiography- fluoroscopy fusion (EFF) requires use of the same vendor x-ray and ultrasound equipment with a workstation housing proprietary software. The methodology used to create image fusion and its clin- ical applications are similar for all current products. The purpose of this review is to describe the emerging EFF technology and its use in congenital and structural heart disease, the novel investiga- tional development of this technology, and future directions for EFF imaging. From Pediatric Cardiology, Children’s Hospital Colorado (P-N.J., M.R.), and Division of Cardiology (D.M.W., E.G., R.A.Q., J.C.M., E.E.S., J.D.C.), University of Colorado School of Medicine, Aurora, Colorado; and Philips Healthcare (A.H.), Andover, Massachusetts. Reprint requests: Pei-Ni Jone, MD, 13123 East 16th Avenue, B100, Aurora, Colo- rado 80045 (E-mail: pei-ni.jone@childrenscolorado.org). 0894-7317/$36.00 Published by Elsevier Inc. on behalf of the American Society of Echocardiography. https://doi.org/10.1016/j.echo.2019.07.023 1