Intracardiac echocardiography with a steerable low-frequency linear-array probe for left-sided heart imaging from the right side: experimental studies.

Despite a need for intracardiac echocardiographic guidance during interventional procedures, an optimal catheter device is not available. The depth of field of catheters bearing 10 to 20 MHz transducers does not allow easy or complete visualization of the left side of the heart from the right side of the heart. Lower frequency transducers would be required to increase the depth of view of such rotational devices. These low-frequency transducers would require an expanded aperture and thus a larger catheter size. Other transducer modalities that could exploit the length of the imaging device rather than the circumference could potentially solve the problem of aperture size. To examine whether a linear-array transducer could provide adequate images of the left side of the heart from the venous side, we employed a prototype 7 MHz linear-array probe with a steerable tip inside eight animal hearts. Atrial and ventricular septal defects were created experimentally. The device was introduced into the right side of the heart through the inferior and superior vena cavae. Intracardiac imaging with this probe allowed visualization of the left side of the heart and major arteries from the right side with excellent image quality. By advancing the probe in various locations in the right side of the heart and using the steerability of this device, we were able to identify useful imaging planes for different cardiac structures. Atrial and ventricular septal defects were also detected easily and delineated clearly. The concept of a low-frequency (< 8 mHz) linear-array probe for intracardiac echocardiography may represent another step toward "whole-heart imaging" from the venous side.(ABSTRACT TRUNCATED AT 250 WORDS)