Initial Experience with a Novel Real-Time Three-Dimensional Intracardiac Ultrasound System to Guide Percutaneous Cardiac Structural Interventions: A Phase 1 Feasibility Study of Volume Intracardiac Echocardiography in the Assessment of Patients with Structural Heart Disease Undergoing Percutaneous Transcatheter Therapy

Background: Intracardiac echocardiographic (ICE) imaging is a modality increasingly used to guide percutaneous cardiac structural interventions. Until recently, ICE imaging has been limited by the presence of only two-dimensional imaging planes and requires considerable catheter manipulation to visualize certain targets. The aim of this study was to assess the feasibility of a new three-dimensional (3D) volumetric ICE system to provide imaging guidance in 15 patients undergoing percutaneous cardiac structural interventions. Methods: The Siemens AcuNav 3D volumetric ICE catheter was used to guide interventions in 15 patients. Imaging was performed at 6 and 8 MHz without color Doppler flow mapping and at 4 and 6 MHz with color Doppler flow mapping. The images were independently reviewed, and the ability to visualize specific structures was assessed by two independent and expert ICE imagers. Results: The majority of patients (n = 11 [73%]) were undergoing percutaneous transcatheter closure of patent foramen ovales (n = 3 [20%]) or atrial septal defects (n = 8 [53%]). Three patients (20%) underwent balloon valvuloplasty for mitral stenosis. One patient (7%) underwent a diagnostic study for congenital heart disease. There were no significant differences in image scores between 3D and two-dimensional imaging without color Doppler in clinically important targets. With color Doppler, there were decreased image scores in the 3D images. Three-dimensional images provided improved imaging of devices and catheters and of the relationship between atrial septal defect devices and the aorta. Conclusion: Three-dimensional volumetric ICE imaging can be successfully used to guide structural heart disease procedures. It has the potential to provide greater anatomic information during interventions. Further improvement in its imaging capabilities is required to improve color Doppler mapping and volume size capabilities.