We developed prototype catheters for real-time three- dimensionalintracardiac echo (4D ICE) imaging. The catheter tips contained a low profile64-element, 6.2 MHz phased array transducer and integrated micromotor, allowingoscillation of the transducer in the elevation direction. The tips wereintegrated with two-way deflectable 10 Fr catheters and used in in-vivo animaltesting at multiple facilities. The 4D ICE catheters were capable of imaging a90 azimuth by up to 180 elevation field of view. Volume rates ranged from 1vol/sec (180 elevation) to approximately 10 vol/sec (45 elevation). Wesuccessfully imaged electrophysiology catheters, atrial septal punctureprocedures, and detailed cardiac anatomy. The elevation oscillation enabled 3Dvisualization of devices and anatomy providing new clinical information andperspective not possible with current 2D imaging catheters.