CLINICAL FEASIBILITY OF AN 0.018-INCH INTRAVASCULAR ULTRASOUND IMAGING DEVICE
Authors: J Tobis, P Hall, L Maiello, A Itoh, Yt Jang, S Salmon, A Colombo
Journal: Circulation (1995)

Clinical feasibility of 0.018-inch intravascular ultrasound imaging device Takafumi Hiro, MD, Patrick Hall, MD, Luigi Maiello, MD, Akira Itoh, MD, Antonio Colombo, MD, Yue-Teh Jang, PhD, Stephen M. Salmon, BS, and Jonathan M. Tobis, MD, FACC Irvine, Calif, and Milan, Italy Objectives Intravascular ultrasound imaging (IVUS) is limited by the size of the imaging catheter. To facilitate imaging before and during interventions, a 30-MHz ultrasonic imaging device was developed that is the same dimension as a 0.018- inch guide wire. The purpose of this study was to evaluate the clinical feasibility of this device. Methods and Results The imaging core was tested in 8 patients with the use of a monorail guiding sheath that was advanced through a 7F catheter. In addition, after coronary interventions, the standard guide wire was removed, the imaging core was placed inside a compatible balloon, and imaging was performed. In 4 patients, imaging was also per- formed with a standard 3.2F IVUS catheter. The lumen-plaque interface and the media-plaque interface were clearly visual- ized in all patients. There was no detectable loss in image quality between the new imaging device and the larger IVUS catheter, and measurements of lumen cross-sectional area were not statistically different. Conclusions Improvements in manufacturing technology have permitted the development of a mechanically rotating ultrasound imaging core 0.018 inches in diameter. It is compatible with current balloon catheters without degradation of image quality. (Am Heart J 1998;136:1017-20.) Intravascular ultrasound (IVUS) is useful as a diag- nostic device and as a guide during interventional pro- cedures. 1-8 However, IVUS is time consuming and requires exchanges between interventional devices and imaging catheters. The development of a smaller imag- ing device that could be exchanged with a guide wire could facilitate the use of intracoronary ultrasound imaging. To meet this requirement, a 30-MHz ultra- sonic imaging core was developed that is the same dimension as a 0.018-inch guide wire. The purpose of this study was to test the clinical fea- sibility of this imaging core that can be exchanged for a 0.018 inch guide wire and can fit through the shaft of existing balloon catheters. Methods 0.018-Inch imaging core A magnified view and a structure diagram of a 2.9F imaging catheter and of the 0.018-inch-diameter, 30-MHz imaging core From the University of California Irvine, Cuore Columbus, and CVIS, Inc. Submitted August 8, 1996; accepted December 15, 1997. Supported in part by NIH Grant R01-HL45077-03. Presented in part at the 68th Scientific Sessions of the American Heart Association, Anaheim, Calif, 1995. Reprint requests: Jonathan M. Tobis, MD, Department of Medicine/Cardiology, Uni- versity of California, Irvine, Bldg 53, Rte 81, Room 100, 101 The City Drive South, Orange, CA 92668-3298. Copyright © 1998 by Mosby, Inc. (CVIS, Inc, Sunnyvale, Calif) are shown in Figs 1 and 2. The 2.9F imaging catheter has a 0.029-inch imaging core, which is the smallest commercially available catheter (MicroView, CVIS). The entire shaft of the catheter rotates within a protec- tive plastic sheath and can be advanced or withdrawn along the long axis of the sheath. The transducer is placed at a 5 degree angle to the long axis of the catheter to diminish near- field artifact. The distal end of the imaging device has an 8- mm-long flexible tip, but this wire does not extend beyond the distal end of the protective sheath. The transducer of the 0.018-inch-diameter imaging core is also displaced 5 degrees off the longitudinal axis to prevent near-field artifact. Although the diameter of the imaging core is the same as a 0.018-inch guide wire, the characteristics of this imaging core are significantly different from a guide wire, and it is not meant to extend beyond the sheath or be used as a guide wire. Clinical studies The 0.018-inch imaging core was tested in 8 patients who underwent interventional procedures at The Clinica Cuore Columbus, Milan, Italy. All patients gave informed consent. The study was approved by the Human Research Committee at the hospital. During interventional procedures, the standard guide wire was removed and the 0.018-inch imaging core was directly advanced through the central lumen to image through the angioplasty balloon. After the balloon was removed, these patients were also studied with the 0.018-inch imaging core