Intracardiac Forward-Looking Ultrasound Imaging Catheters Using Capacitive Micromachined Ultrasonic Transducers
Atrial fibrillation is the most common sustained arrhythmia that now affects approximately 2.2 million adults in the United States alone. Minimally invasive catheter-based electrophysiological interventions have revolutionized the management of cardiac arrhythmias. We are developing forward-viewing ultrasound imaging catheters based on two types of transducer arrays using the capacitive micromachined ultrasonic transducer technology: A 10-MHz, 24-element MicroLinear (ML) array with a footprint of 1.7 mm × 1.3 mm, and a 10-MHz, 64-element annular ring array with an outside diameter of 2.6 mm and inner diameter of 1.6 mm. Both arrays are integrated with custom-designed front-end electronic circuitry to overcome the performance degradation associated with long cables in the catheter. The ML and ring arrays provide real-time 2-D and 3-D images, respectively, in front of the catheter tip. Using the ML array, we demonstrated ex-vivo images of the left atrial appendage in an isolated Langendorff-perfused rabbit heart model and in-vivo images of heart through the open chest in a porcine animal model. We used the ring array to demonstrate 3-D images of coronary stents and an anatomic cast of a left atrial model.
KeywordsIntracardiac imaging Intracardiac echocardiography Ultrasound imaging Forward looking Cardiac electrophysiology Capacitive micromachined ultrasonic transducer (CMUT) Catheter
This work was supported by the National Institutes of Health under grant HL67647, USA. We thank National Semiconductor (Santa Clara, CA) for their valuable support in the design and fabrication of the IC. CMUT fabrication was done at the Stanford Nanofabrication Facility (Stanford, CA), which is a member of National Nanotechnology Infrastructure Network. Pac Tech USA, Inc. (Santa Clara, CA) provided electrodeless Ni/Au UBM plating and solder bumping.
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