A probe navigation methods and devices for use in medical diagnoses and procedures are provided. A probe that is inserted in a walled area within a subject has a distal end on which at least first and second opposing transducers are mounted. The transducers track movement of the probe end with respect to the walls of the walled area. The distal end of the probe may closely approach a wall to enter an area such that the first transducer is no longer able to properly sense it, commonly referred to as a blanking region. Tracking information of the movement of the probe away from an opposing wall generated by the second transducer is then used to provide tracking of the distal end of the probe relative to the wall the first transducer is no longer able to sense.

A method includes transmitting electrical signals between one or more pairs of body-surface electrodes attached to a body of a patient. Electrical potentials resulting from the transmitted electrical signals are acquired by an outer-facing electrode and an inner-facing electrode of a medical probe inserted in an organ of the patient. A proximity of the medical probe to surface tissue of the organ is estimated based on the electrical potentials acquired by the outer-facing electrode. A position of the medical probe within the organ is estimated based on the electrical potentials acquired by the inner-facing electrode.

A stretch-measurement probe includes an elongate outer sleeve, expansion feature associated with a distal portion of the outer sleeve, and an elongate inner rod disposed at least partially within the outer sleeve. The expansion feature is configured to allow a longitudinal distance between a proximal end of the outer sleeve and the distal end of the outer sleeve to be varied.

A method of performing impedance measurements on a subject. The method includes using a processing system to determine at least one impedance measurement to be performed, and at one electrode arrangement associated with the determined measurement. A representation of the arrangement is displayed so the impedance measurement can be performed once the electrodes have been arranged in accordance with the displayed representation.

In some embodiments, a body cavity shape of a subject is reconstructed based on intrabody measurements of at least one property of an electromagnetic field by an intrabody probe (for example, a catheter probe) moving within a plurality of electrical fields intersecting the body cavity. In some embodiments, the electrical fields are generated at least in part from electrodes positioned in close proximity, for example, within 1 cm, of the body cavity. In some embodiments, the body cavity is a chamber of a heart (for example, a left atrium or left ventricle), and the electrodes used to generate the electrical field are positioned in the coronary sinus, a large vein occupying the groove between the left atrium and left ventricle. In some embodiments, known distances between measuring electrodes are used in guiding reconstruction, potentially overcoming difficulties of reconstruction from measurements of non-linear electrical fields.

A plurality of electrophysiological signals measured by a respective plurality of electrodes carried by a multi-dimensional catheter can be sorted relative to a direction of interest, such as a cardiac activation wavefront direction. An electroanatomical mapping system can be used to determine the orientation of the multi-dimensional catheter relative to the direction of interest. For example, the user can manually adjust the orientation by manipulating a slider, a wheel, or a similar graphical user interface control. As another example, the user can draw a presumed orientation on a geometric model. Once the orientation is determined, the system can sort the plurality of electrophysiological signals and output a graphical representation of the sorted plurality of electrophysiological signals, for example as a plurality of traces.

The present disclosure is directed to measuring impedance across a plurality of electrode pairs. The disclosed systems and methods may simultaneously provide drive signals between electrode pairs and then sense the voltage signals that develop at the electrodes. Digital signal processing may be used to synchronously demodulate the voltage signal at each electrode to determine impedances at the electrodes. Each electrode pair may be driven at a unique frequency to allow for significantly increasing a number of electrode pairs and/or increasing drive current magnitudes. Synchronous demodulation allows the unique frequencies to be detected independent of each other while minimizing crosstalk. Typically, the drive frequencies are made orthogonal by setting the drive frequencies at harmonics of a common base frequency and measuring a response over an integer number of cycles. In an embodiment, quadrature demodulation may occur providing a real component for resistive impedance and an imaginary component for reactive impedance.

A method includes, in a processor, receiving signals from (i) a first position sensor disposed on a shaft of a catheter, and (ii) a second position sensor disposed on a distal end of a sheath of the catheter. Based on the signals received from the first position sensor and the second position sensor, an event is detected in which an expandable distal-end assembly of the catheter is being withdrawn into the sheath while still at least partially expanded. A responsive action is initiated in response to detecting the event.

A system for differentiating between magnetic field distortion and physical movement in a hybrid magnetic and impedance tracking system can comprise a first drive patch and a second drive patch configured to generate an electrical field within the body for locating an electrode on the medical device, a magnetic localization system configured to generate a magnetic field, a magnetic sensor configured to receive signals from the magnetic localization system, and an electronic control unit configured to receive location data from the impedance localization system and magnetic sensor location data from the magnetic localization system. The electronic control circuit can be configured to detect a location change of the magnetic sensor and use the drive patch location data and magnetic sensor location data to determine whether the detected location change of the magnetic sensor is caused by a magnetic field distortion or a physical movement of the magnetic sensor.

A transmitting element for generating a magnetic field for tracking of an object includes a first spiral trace that extends from a first outer origin inward to a central origin in a first direction. A second spiral trace can extend from the central origin outward to a second outer origin in the first direction. The second spiral trace can extend from the central origin to the second outer origin in the first direction. The first spiral trace and the second spiral trace can be physically connected at the central origin to form the fluorolucent magnetic transmitting element and at least a portion of the first spiral trace overlaps at least a portion of the second spiral trace.