Abstract: A method for calibrating impedance includes coupling at least first, second, and third electrodes at respective locations to a surface of a body of a subject. A first current passing through the body between the first and second body-surface electrodes is measured, and a second current passing through the body between the first and third body-surface electrodes is measured. From the first and second currents, a contact factor is derived that is indicative of the impedance between at least one of the body-surface electrodes and the surface of the body. Also described are methods for sensing the position of a probe and for detecting tissue contact based on a relation between currents from the probe to body-surface electrodes.

Abstract: During acquisition of ultrasound data in a medical imaging procedure, three-dimensional model of a structure being imaged, e.g., an electroanatomical map, is co-displayed and visually marked, to indicate progress of data acquisition. The plane of intersection successive two-dimensional images are marked on the as a line or colored region on the three-dimensional model. This display enables the operator to determine regions where sufficient data have been captured, and guides the operator to areas where additional data collection is still needed. Various color schemes are used to indicate the relative sufficiency of data collection.

Abstract: A method for producing a coil assembly includes overlaying printed circuit traces on a core. The traces include terminals for coupling to conductive connections on a base on which the coil assembly is to be mounted. Two or more wires are wrapped around the core so as to define two or more coils, wrapped in different, respective directions. The ends of the wires are coupled to the printed circuit traces, so as to connect the wires through the traces to the terminals.

Abstract: A method for calibrating a medical system capable of generating a magnetic field for tracking a position of a medical device has various steps such as defining a mapping volume within the generated magnetic field and placing a metallic object within the mapping volume. A sensor is aligned at a first point within the mapping volume and the magnetic field at the first point is measured with the sensor to establish a first coordinate position (Xi, Yi, Zi). An interpolation technique in one embodiment and an extrapolation technique in another embodiment are used in the calibration method.

Abstract: A medical device for placement at a site in a patient's body and for controlling pH levels at the site in the patient's body includes one or more structural components made of a first biodegradable and/or bioabsorbable material or, alternatively, one or more structural components having a coating thereon made of a first biodegradable and/or bioabsorbable material. The device also includes a buffering agent and at least one second biodegradable and/or bioabsorbable material on or in the one or more structural components, or alternatively, on or in the coating on the one or more structural components. The at least one second biodegradable and/or bioabsorbable material encapsulates the buffering agent and the buffering agent is dispersed from the at least one second biodegradable and/or bioabsorbable material in response to hydrolysis of the first biodegradable and/or bioabsorbable material.

Abstract: Apparatus and methods are provided for determining in near realtime the position of a probe placed within a living body. Electric currents are driven between one or more electrodes on the probe and electrodes placed on the body surface. The impedance between the probe and each of the body surface electrodes is measured, and three-dimensional position coordinates of the probe are determined based on the impedance measurements. Dynamic compensation is provided for changing impedance of the body surface and its interface with the electrodes, resulting from such causes as electrode peel-off and changes in moisture and temperature. The compensation improves the accuracy of, inter alia, medical procedures, such as mapping the heart or performing ablation to treat cardiac arrhythmias.

Abstract: A method for delivering a cell to a heart of a patient comprises the steps of providing an apparatus for intracardiac drug administration comprising a catheter wherein the catheter has at least one position sensor which generates signals responsive to the position of a catheter and a drug delivery device for delivering the cell. The catheter is inserted into a chamber of the heart at a site and the cell is delivered to the site with the drug delivery device in response to the signals from the position sensor. Typical cells useful for delivery are either myoblasts or myocytes. These cells may be utilized as either an expression vector for promoting angiogenesis or for cell transplantation and fusion through myogenesis.

Abstract: A calibration apparatus includes a motion assembly, which is arranged to move an imaging probe through a calibration point having known coordinates. The imaging probe includes an ultrasound transducer and a position sensor for acquiring concurrently a first sequence of ultrasound images and a second sequence of position measurements. The apparatus further includes a marking circuit, which is arranged to mark an ultrasound image that is acquired by the ultrasound transducer in the first sequence when the imaging probe is at the calibration point. A processor is arranged to calibrate a time offset between the first and second sequences by associating the marked ultrasound image in the first sequence with a position measurement in the second sequence whose coordinates match the coordinates of the calibration point.

Abstract: Apparatus for tracking an object includes a plurality of field generators, which generate electromagnetic fields at different, respective frequencies in a vicinity of the object, and a radio frequency (RF) driver, which radiates a RF driving field toward the object. A wireless transponder is fixed to the object. The transponder includes at least one sensor coil, in which a signal current flows responsive to the electromagnetic fields, and a power coil, which receives the RF driving field and conveys electrical energy from the driving field to power the transponder. The power coil also transmits an output signal responsive to the signal current to a signal receiver, which processes the signal to determine coordinates of the object.

Abstract: Apparatus for assessing field distortion includes a probe and a processor. The probe includes a mechanical fixture for placement at a location to be tested, and one or more field generators, which are attached to the mechanical fixture and are arranged to generate respective magnetic fields. The probe further includes one or more field sensors, which are attached to the mechanical fixture at known positions with respect to the one or more field sensors and are arranged to sense the magnetic fields generated by the one or more field generators and to output signals responsively to the sensed magnetic fields. The processor is arranged to process the signals so as to assess a distortion of the magnetic fields sensed by the field sensors at the tested location.

Abstract: A method for treating atrial fibrillation in a heart of a patient includes placing an ultrasonic catheter in a first chamber of the heart; acquiring two-dimensional ultrasonic images of a second chamber of the heart and at least a portion of surrounding structures of the second chamber using the ultrasonic catheter placed in the first chamber; reconstructing a three-dimensional ultrasonic image based on the two-dimensional ultrasonic images; displaying the reconstructed three-dimensional ultrasonic image; identifying at least one key landmark on the reconstructed three-dimensional ultrasonic image; marking the least one key landmark on the reconstructed three-dimensional ultrasonic image; penetrating the septum for accessing the second chamber of the heart while using the marked at least one key landmark for guidance; positioning a sheath through the penetrated septum and within the second chamber of the heart; inserting an ablation catheter through the sheath and into the second chamber of the heart; and abl

Abstract: A method for position sensing includes placing at a known position within a body of a subject a reference probe including at least one reference electrode. Electrical currents are passed through the body between the reference electrode and body surface electrodes. Characteristics of the electrical currents are measured and are used to generate an approximation of the known position of the reference probe. A correction factor is determined based on a relationship between the approximation and the known position. A target probe including at least one target electrode is placed within the body of the subject and second electrical currents are passed through the body between the target electrode and the body surface electrodes. Characteristics of the second electrical currents are measured and used to generate a calculated position of the target probe. The correction factor is applied to correct the calculated position.

Abstract: An orifice device for delivering a drug includes an inner member having a proximal end and a distal end. A winding is helically wound around the inner member. The winding and the inner member define a first channel for carrying a drug therethrough. An inlet is at the proximal end of the winding and an outlet is at the distal end of the winding.

Abstract: Apparatus for driving current in a power circuit of a medical device inserted into a body of a subject includes a power transmitter, which is adapted to generate, in a vicinity of the body, an electromagnetic field having a predetermined frequency capable of inductively driving the current in the power circuit. A passive energy transfer amplifier, having a resonant response at the frequency of the electromagnetic field is placed in proximity to the medical device so as to enhance the current driven in the power circuit by the electromagnetic field.

Abstract: Apparatus for performing a medical procedure on a tissue within a body of a subject includes a wireless tag configured to be fixed to the tissue and adapted to emit radiation, thereby causing first signals to be generated indicative of a location of the tag in the body. An invasive medical tool includes a probe, which is adapted to penetrate into the body so as to reach the tissue. A handle is fixed proximally to the probe, for manipulation by an operator of the tool. A display, mounted on the handle, presents a visual indication to the operator of an orientation of the probe relative to the tag. A processing unit processes the first signals so as to determine coordinates of the tag relative to the probe, and drives the display responsive to the coordinates.

Abstract: An Apparatus for determining the disposition of an object relative to a reference frame includes at least one field generator, which generates an electromagnetic field in a vicinity of the object and at least one transducer, which is fixed to the object. The at least one transducer vibrates at a predetermined vibrational frequency and emits energy, responsive to an interaction of the electromagnetic field therewith. One or more detectors in a vicinity of the object are also utilized to detect the energy emitted by the transducer and generate signals in response thereto. A signal processor is also included for receiving and processing the detector signals to determine coordinates of the object.

Abstract: Apparatus for locating a tissue within a body of a subject includes an acoustic tag configured to be fixed to the tissue and adapted, responsive to acoustic waves incident thereon, to return acoustic echoes. Acoustic transducers are placed at respective positions so as to direct the acoustic waves into the body toward the tissue and to receive the acoustic echoes returned from the tag responsive to the acoustic waves, generating first signals responsive to the received echoes. Transducer position sensors are coupled respectively to the acoustic transducers so as to generate second signals indicative of the respective positions of the acoustic transducers in an external frame of reference. A processing unit processes the first signals and the second signals so as to determine coordinates of the acoustic tag in the external frame of reference.

Abstract: Apparatus for determining the position of an object within a body of a subject includes at least one acoustic wave generator, adapted to direct a first acoustic wave toward the body at a first frequency. An acoustic tag is adapted to be fixed to the object, the tag including a shell defining a cavity therein and a medium contained within the shell, such that responsive to incidence thereon of the first acoustic wave, the tag emits a second acoustic wave at a second frequency, different from the first frequency. One or more detectors are adapted to detect the second acoustic wave and to generate signals responsive thereto. A signal processor is coupled to process the signals so as to determine coordinates of the object in the body.

Abstract: A position sensing system includes a probe adapted to be introduced into a body cavity of a subject. The probe includes a magnetic field transducer and at least one probe electrodes. A control unit is configured to measure position coordinates of the probe using the magnetic field transducer. The control unit also measures an impedance between the at least one probe electrodes and one or more points on a body surface of the subject. Using the measured position coordinates, the control unit calibrates the measured impedance.

Abstract: Apparatus is provided for tracking an object in a body of a patient in the presence of an interfering article. A set of one or more radiators are adapted to generate an energy field at a fundamental frequency in a vicinity of the object. A position sensor, fixed to the object, is adapted to generate a signal responsive to the energy field. A control unit has access to a database of one or more harmonic frequency patterns associated with one or more respective specific types of interfering articles.