Integrated catheter for 3-D intracardiac echocardiography and ultrasound ablation

We have integrated real-time three-dimensional (RT3D) intracardiac echocardiography and ultrasound ablation. The device uses a 9 Fr (3 mm O.D.) catheter lumen with a 14 Fr (4.7 mm O.D.) tip. Real-time 3D imaging is achieved with a forward-looking 112 element, 5 MHz two-dimensional array built on a multi-layer flexible interconnect circuit. Transducer elements typically showed a 21% bandwidth and a pulse-echo insertion loss of 80 dB. The imaging array, attached to our real time 3-D scanner was used to image tissue phantoms and a fixed sheep heart. The ablation transducer is a ring of 10 MHz PZT-4 placed around the imaging array. The ring has a 4.5 mm O.D. and a 3.1 mm I.D. for a total area of 33.4mm². Using a hydrophone, the spatial-peak, temporal-average intensity of the ablation ring was measured at a maximum of 500 cycles per burst and a PRF of 10.3 kHz to be 16.1 W/cm². The ablation ring was then used to heat tissue mimicking rubber with absorption comparable to tissue. A temperature rise of 14 °C was recorded. In our final experiment, the imaging array was used to view a 1 cm thick piece of beef with a 12 mm hole in it. The ablation ring was then used to create a lesion adjacent to the hole.