Ultrasound device for axial ranging

Abstract

A treatment tool such as a catheter, MIS or other surgical tool apparatus for placement within a heart chamber, organ aperture or other body opening and axial ranging therein, the apparatus particularly adapted for laser-assisted percutaneous transmyocardial revascularization (MTR). At the distal end of the tool is an annular ultrasound transducer with associated structure, positioned to transmit ultrasound signals substantially axially aligned with the axis of the treatment tool to the cardiovascular tissue, the transducer further receiving returning signals from the cardiovascular tissue to be treated. In a preferred embodiment, the transducer comprises a piezoelectric crystal material. The transducer assembly is attached to the distal tip of the tool such that a laser delivery means or other functional device can be extended through the lumen of the tool and the annular ultrasound transducer. In a preferred embodiment, the invention is a modular ultrasound device capable of being detachably attached to a steerable catheter, MIS or other surgical tool apparatus. The system also comprises a signal interface extending from the ultrasound transducer and signal processing component operatively connected to the signal interface for real time determination of at least one boundary surface of cardiovascular tissue relative to one or more positions of the distal tip of the treatment tool. A method of delivering laser energy to tissue is disclosed, the method including the steps of positioning the firing tip of a laser delivery means adjacent the front surface of the tissue, delivering laser energy to the tissue, transmitting ultrasound energy to the tissue, receiving ultrasound signals reflected from at least the rear surface of the tissue, and determining the distance betwveen the firing tip of the laser delivery means and the rear surface of the tissue. In a preferred embodiment, the method includes quantitative determination of the contractility or motion of the beating heart, such that changes in the depth of tissue can be used to control the channel depth or other treatment parameters. Retrolasing can also be achieved by mechanically piercing the tissue to a determined depth based on axial ranging measurements, and retracting the treatment tool while simultaneously delivering laser energy therefrom.