Catheter ultrasound transducer

A device for use with a blood vessel of a subject that extends from a chamber of a heart of the subject, the device comprising:

• a catheter ultrasound transducer comprising one or more piezoelectric elements configured to ablate tissue of an ostium of the blood vessel by applying ultrasound energy to tissue of the ostium;
• and
• an expandable positioner configured to envelope at least a portion of the catheter ultrasound transducer and to position the catheter ultrasound transducer in the blood vessel by contacting a wall of the blood vessel;
• one or more electrodes located on the expandable positioner and configured to record electrical activity in tissue;
• a system processor in communication with the one or more piezoelectric elements and configured to adjust a level of the ultrasound energy emitted from the one or more piezoelectric elements based on the recorded electrical activity in the tissue.

A device for use with a blood vessel of a subject that extends from a chamber of a heart of the subject, the device comprising:

• a catheter ultrasound transducer comprising one or more ablative piezoelectric elements configured to ablate tissue of an ostium of the blood vessel by applying ultrasound energy to tissue of the ostium, and a piezoelectric element temperature sensor;
• and
• an expandable positioner configured to envelope at least a portion of the catheter ultrasound transducer and to position the catheter ultrasound transducer in the ostium of the blood vessel by contacting a wall of the blood vessel;
• and
• a system processor in communication with the one or more ablative piezoelectric elements and configured to regulate a parameter of the ultrasound energy emitted from the one or more ablative piezoelectric elements based on a temperature detected by the piezoelectric element temperature sensor.