Abstract: A treatment catheter (10) carries an elongated ultrasonic emitter (20) extending in the lengthwise direction of the catheter. The array is flexible in all directions transverse to the lengthwise direction. The treatment catheter is inserted into a chamber of the heart and brought to a desired configuration such as a substantially closed loop. The treatment catheter is then biased into engagement with the wall of the heart by an expansible balloon (62) or other expansible structure, which may be carried on a separate stabilizer catheter (60). While the treatment catheter is engaged with the heart wall, the array is actuated to ablate tissue along a path having a shape corresponding to the configuration of the treatment catheter.

Abstract: A tubular anatomical structure in a mammalian subject is occluded by directing ultrasonic energy from outside of the body. For example, a male subject may be sterilized by directing ultrasonic energy through the skin of the scrotum, onto the vas deferens. The focal spot of an ultrasonic transducer may be registered with the structure to be treated by means of guide members on a probe holding the transducer. The procedure is simple and can be entirely non-invasive. Apparatus for performing this and other treatments may be provided as a disposable unit, and the guide members may be arranged to hold a fold of tissue without substantially obstructing the sonic path from the transducer to the fold.

Abstract: Methods and apparatus for treating cardiac arrhythmias by ablating myocardial fibers within a pulmonary vein through use of a catheter. For example, the ablative element of the catheter is rotated around an axis to ablate a partial or complete loop of tissue within the pulmonary vein so as to block the transmission into the cardiac tissue of electrical signals originating or propagating from myocardial fibers within a pulmonary vein. In other examples, signals from the catheter are monitored to determine whether the ablative element is in contact with the wall of the pulmonary vein. Additional apparatus allow precise angular positioning of the ablative element within the lumen of the pulmonary vein. Apparatus and methods for detecting the properties of the tissue within the pulmonary vein, locating myocardial fibers, selectively ablating such fibers, and determining if such fibers are ablated are also disclosed.

Abstract: A probe such as an endoscope equipped with a biopsy needle is guided to a target in or adjacent to the respiratory system. The position of the probe is monitored and a representation of the probe is superposed on a previously acquired image of the respiratory system and adjacent tissues. Artifacts caused by motion due to respiration are suppressed by monitoring the respiratory state of the patient and acquiring the probe position when the respiratory state of the patient is equal to the respiratory state of the patient during image capture.

Abstract: A collapsible ultrasonic reflector incorporates a gas-filled reflector balloon, a liquid-filled structural balloon an ultrasonic transducer disposed within the structural balloon. Acoustic energy emitted by the transducer is reflected by a highly reflective interface between the balloons. In a cardiac ablation procedure, the ultrasonic energy is focused into an annular focal region to ablate cardiac tissue extending in an annular path along the wall. Devices for stabilizing the balloon structure and for facilitating collapse and withdrawal of the balloon structure are also disclosed.

Abstract: Magnetic resonance information acquired by a movable magnetic resonance instrument is used to monitor hyperthermia treatments such as tissue ablation. The instrument may include both the magnetic resonance equipment and an energy applicator such as a high intensity focused ultrasound unit. The treatment can be conducted under automatic control after the operator marks a treatment volume on an image of the subject, such as a magnetic resonance image acquired using the movable magnetic resonance instrument. The automatic treatment can be based on interpolation of tissue response curves at plural test points near the treatment volume. The system can also provide automatic supervisory control during manual operation, to prevent application of heat to sensitive anatomical structures.

Abstract: High intensity focused ultrasound heating is provided by applying therapeutic ultrasonic waves using an array of transducers. Cavitation is detected by using some or all of the transducers in the array to detect ultrasonic waves emanating from or reflected from the patient's body or the interface. A feedback signal is generated based on such detection. If the feedback signal indicates the presence of cavitation, the therapeutic ultrasonic waves are terminated or altered. Obstacles to ultrasound transmission, such as bony structures or bubbles at the interface between the transducer array and the patient can be detected using the same transducers.

Abstract: An apparatus and method for applying sonic energy within the body of the living subject. A probe for applying sonic energy within the body of a subject comprises a probe body having a proximal and a distal end adapted for insertion into the body of a subject, a spatially-distributed sonic transducer disposed adjacent to the distal end of the probe body and a device for moving one portion of the spatially-distributed transducer relative to another portion of the transducer while the distal end of the probe is disposed within the body of the subject.

Abstract: A multi-layer piezoelectric transducer includes a first polymeric layer of piezoelectric material having spaced apart first and second surfaces and a second polymeric layer of piezoelectric material having spaced apart first and second surfaces. A first ground layer overlies the first surface of the first polymeric layer and a second ground layer overlies the first surface of the second polymeric layer. A signal layer is sandwiched between the second surfaces of the first and second polymeric layers.

Abstract: A method and device for recording multiple information volumes on a record carrier, usually called multi-session recording, is described. The device has a mapping unit (31) for opening a session by recording intro data comprising a first buffer zone at the beginning of the start zone of the volume, and a session control block (SDCB) in a remaining blank area of the start zone after the buffer zone. The session control block comprises volume data indicative of the status and the contents of the session. The session is closed by recording session control data indicating that the information volume is closed in the remaining blank area, and closure data after the last user information recorded in the data zone for constituting the end zone of the volume. Further the device has a detecting unit (32) for retrieving the session control block from said start zone.

Abstract: An apparatus and method for applying sonic energy within the body of the living subject. A probe for applying sonic energy within the body of a subject includes a probe body having a proximal and a distal end adapted for insertion into the body of a subject, a spatially-distributed sonic transducer disposed adjacent to the distal end of the probe body and a device for moving one portion of the spatially-distributed transducer relative to another portion of the transducer while the distal end of the probe is disposed within the body of the subject.

Abstract: A field transducer (30) for determining position or orientation in a medical instrument locating system is placed at an arbitrary position or orientation with respect to a feature (62) of the instrument (46). The transducer (30) may be attached at a arbitrary location on the instrument (46), or the instrument (400, 404) may be bent as desired by the user. A transform relating position or orientation of feature of the instrument to position or orientation of the tranducer is obtained in a caliration cycle. A field transducer may be part of a disposable unit which is irrevocably altered when used with an instrument so that the unit cannot be reused.

Abstract: A method of treating cardiac arrhythmias by ablating a portion of the myocardial fibers within a pulmonary vein. Myocardial fibers within a pulmonary vein are located and ablated to block conduction of electrical signals to the heart from ectopic foci within the pulmonary vein. The myocardial fibers are located and selectively ablated so as to avoid having to create a circumferential conduction block around the pulmonary vein or ostium. Devices for locating the myocardial fibers, selectively ablating such fibers, and directing ablative energy, are also disclosed.

Abstract: A magnetic position and orientation determining system uses magnetic fields, desirably including uniform fields from Helmholtz coils positioned on opposite sides of a sensing volume and gradient fields generated by the same coils. By monitoring field components detected at the probes during application of these fields, the position and orientation of the probe in the field can be deduced. A representation of the probe can be superposed on a separately acquired image of the subject to show the position and orientation of the probe with respect to the subject.

Abstract: Apparatus and methods for ablating tissue surrounding a tubular anatomical structure such as the wall of a blood vessel or prostatic tissue surrounding the urethra. The apparatus includes an ultrasonic emitter such as a cylindrical emitter and an inflatable annular lens balloon surrounding the ultrasonic emitter. The lens balloon is inflated with a liquid having acoustic velocity different than that of the surrounding medium, so as to form an annular refracting surface. The acoustic energy from the emitter is focused into an annular focal region.

Abstract: A collapsible ultrasonic reflector incorporates a gas-filled reflector balloon, a liquid-filled structural balloon an ultrasonic transducer disposed within the structural balloon. Acoustic energy emitted by the transducer is reflected by a highly reflective interface between the balloons. In a cardiac ablation procedure, the ultrasonic energy is focused into an annular focal region to ablate cardiac tissue extending in an annular path along the wall. Devices for stabilizing the balloon structure and for facilitating collapse and withdrawal of the balloon structure are also disclosed.

Abstract: Magnetic resonance information acquired by a movable magnetic resonance instrument is used to monitor hyperthermia treatments such as tissue ablation. The instrument may include both the magnetic resonance equipment and an energy applicator such as a high intensity focused ultrasound unit. The treatment can be conducted under automatic control after the operator marks a treatment volume on an image of the subject, such as a magnetic resonance image acquired using the movable magnetic resonance instrument. The automatic treatment can be based on interpolation of tissue response curves at plural test points near the treatment volume. The system can also provide automatic supervisory control during manual operation, to prevent application of heat to sensitive anatomical structures.

Abstract: A system for determining the disposition of a probe within the body of a patient includes a probe having probe field transducers and one or more reference field transducers. The reference field transducers are affixed to a rigid but repositionable frame constructed to allow the transducers to be positioned in close proximity to the body. Non-ionizing fields are transmitted and detected between the probe and reference field transducers, and from the detected fields the relative disposition of the probe with respect to the reference field transducers is determined.

Abstract: A field transducer (30) for determining position or orientation in a medical instrument locating system is placed at an arbitrary position or orientation with respect to a feature (62) of the instrument (46). The transducer (30) may be attached at an arbitrary location on the instrument (46), or the instrument (400, 404) may be bent as desired by the user. A transform relating position or orientation of a feature of the instrument to position or orientation of the transducer is obtained in a calibration cycle. A field transducer may be part of a disposable unit which is irrevocably altered when used with an instrument, so that the unit cannot be reused.

Abstract: A treatment catheter (10) carries an elongated ultrasonic emitter (20) extending in the lengthwise direction of the catheter. The array is flexible in all directions transverse to the lengthwise direction. The treatment catheter is inserted into a chamber of the heart and brought to a desired configuration such as a substantially closed loop. The treatment catheter is then biased into engagement with the wall of the heart by an expansible balloon (62) or other expansible structure, which may be carried on a separate stabilizer catheter (60). While the treatment catheter is engaged with the heart wall, the array is actuated to ablate tissue along a path having a shape corresponding to the configuration of the treatment catheter.