Transesophageal real-time three-dimensional echocardiography - Methods and initial in vitro and human in vivo studies

OBJECTIVES The purpose of this study was to develop a transesophageal probe that: 1) enables on-line representation of the spatial structures of the heart, and 2) enables navigation of medical instruments. BACKGROUND Whereas transthoracic real-time 3-dimensional (3D) echocardiography could recently be implemented, there is still no corresponding transesophageal system. Transesophageal real-time 3D echocardiography would have great potential for numerous clinical applications, such as navigation of catheters. METHODS The newly developed real-time 3D system is based on a transesophageal probe in which multiple transducers are arranged in an interlaced pattern on a rotating cylinder. This enables continuous recording of a large echo volume of 70 min in length and a sector angle of 120 degrees. The presentation of the volume-reconstructed data is made with a time lag of < 100 ms. The frame rate is up to 20 Hz. In addition to conventional imaging, the observer can obtain a stereoscopic image of the structures examined with red/blue goggles. RESULTS It was shown in vitro on ventricle- and aorta-form agar models and in vivo that the system enables excellent visualization of the 3D structures. Shape, spatial orientation, and the navigation of various catheters (e.g., EPS-catheter, Swan-Ganz-catheter), stents, or atrial. septal defect occluders could be recorded on-line and stereoscopically depicted. The size of the echo sector enables a wide field of view without changing the position of the probe. CONCLUSIONS Transesophageal real-time 3D echocardiography can be technically realized with the system presented here. The in vitro and in vivo studies show particularly the potential for navigation in the heart and large vessels on the basis of stereoscopic images.