Lasso catheter with rotating ultrasound transducer

#The present invention relates generally to medical probes, and particularly to catheters fitted with ultrasound transducers.

#Ablation of myocardial tissue is well known as a treatment for cardiac arrhythmias. In radio-frequency (RF) ablation, for example, a catheter is inserted into the heart and brought into contact with tissue at a target location. RF energy is then applied through an electrode on the catheter in order to create a lesion for the purpose of breaking arrhythmogenic current paths in the tissue. Recently, circumferential ablation of the ostia of the pulmonary veins has gained acceptance as a treatment for atrial arrhythmias, and particularly for atrial fibrillation. For example, U.S. Pat. No. 6,064,902, whose disclosure is incorporated herein by reference, describes a catheter for ablating tissue on the inner wall of a blood vessel, such as a pulmonary vein.

#Some medical imaging systems use catheters that are fitted with ultrasound transducers. For example, U.S. Pat. No. 5,076,278, whose disclosure is incorporated herein by reference, describes an ultrasonic transducer for use in locating devices. The transducer has a curved surface, and is an annular member in shape. An elongated catheter or other device passes through the opening of the annular transducer. As another example, U.S. Pat. No. 5,081,993, whose disclosure is incorporated herein by reference, describes an ultrasonic probe that is inserted into a human organ. In some embodiments, the probe includes an annular ultrasonic transducer assembly.

#FIG. 1 is a block diagram that schematically illustrates a system for ablation and imaging in the heart, in accordance with an embodiment of the present invention;

#FIGS. 2A and 2B are schematic side and sectional views, respectively, of a catheter, in accordance with an embodiment of the present invention;

#FIG. 3 is a schematic sectional view of a catheter, in accordance with another embodiment of the present invention; and

#Lasso catheters may be used for ablating tissue along an arc surrounding an anatomical structure, such as the ostium of a pulmonary vein, and/or for sensing electrical potentials at multiple points that lie on an arc. Example lasso catheters are described in U.S. patent application Ser. No. 12/649,417, filed Dec. 30, 2009, which is assigned to the assignee of the present patent application and whose disclosure is incorporated herein by reference. Lasso catheters provide an easy and reliable way to create annular lesions in the tissue, as well as sensing signals along annular paths.

#Embodiments of the present invention that are described herein provide improved lasso-type medical probes, which comprise integral ultrasound transducers for imaging the treated or diagnosed tissue. In the disclosed embodiments, a medical probe comprises an insertion shaft for insertion into a body of a patient. A resilient end section is fixed to the distal end of the insertion shaft. The end section is formed so as to define an arc that is oriented obliquely relative to the longitudinal axis of the shaft. One or more electrodes, e.g., ablation electrodes and/or potential sensing electrodes, are disposed along the end section. An ultrasound transducer is fixed to the distal end of the shaft, for imaging the vicinity of the arc using ultrasound waves.

#The ultrasound transducer is typically fixed to the insertion shaft such that its field of view covers the tissue that is contacted by the electrodes on the arc-shaped end section. In some embodiments, the ultrasound transducer has an annular field of view that is collinear with the longitudinal axis of the shaft. In this configuration, both the end section electrodes and the ultrasound transducer have annular geometries that complement one another. Thus, the ultrasound transducer provides simultaneous imaging of the entire annular region contacted by the catheter end section (e.g., of the arc-shaped or circumferential lesion formed by the ablation electrodes).