Abstract: A controller-transmitter transmits acoustic energy through the body to an implanted acoustic receiver-stimulator. The receiver-stimulator converts the acoustic energy into electrical energy and delivers the electrical energy to tissue using an electrode assembly. The receiver-stimulator limits the output voltage delivered to the tissue to a predetermined maximum output voltage. In the presence of interfering acoustic energy sources output voltages are thereby limited prior to being delivered to the tissue. Furthermore, the controller-transmitter estimates the output voltage that is delivered to the tissue by the implanted receiver-stimulator. The controller-transmitter measures a query spike voltage resulting from the electrical energy delivered to the tissue by the receiver-stimulator, and computes a ratio of the predetermined maximum output voltage and a maximum query spike voltage. The maximum query spike voltage is computed by detecting a query spike voltage plateau.

Abstract: Receiver-stimulator with folded or rolled up assembly of piezoelectric components, causing the receiver-stimulator to operate with a high degree of isotropy are disclosed. The receiver-stimulator comprises piezoelectric components, rectifier circuitry, and at least two stimulation electrodes. Isotropy allows the receiver-stimulator to be implanted with less concern regarding the orientation relative the transmitted acoustic field from an acoustic energy source.

Abstract: The present invention is a device localization system that uses one or more ultrasound reference catheters to establish a fixed three-dimensional coordinate system within a patient's heart using principles of triangulation. The coordinate system is represented graphically in three-dimensions on a video monitor and aids the clinician in guiding other medical devices, which are provided with ultrasound transducers, through the body to locations at which they are needed to perform clinical procedures. In one embodiment of a system according to the present invention, the system is used in the heart to help the physician guide mapping catheters for measuring electrical activity, and ablation catheters for ablating selected regions of cardiac tissue, to desired locations within the heart.

Abstract: The present invention provides systems, methods, and devices for orienting image data derived from body tissue. An imaging assembly is introduced into the body of a patient and rotated about an axis. A tracking beam mechanically associated with the imaging assembly is generated, such that the tracking rotates about the axis in unison with the imaging assembly. An angle that the rotating tracking beam makes between a reference rotational orientation and a reference point is determined. The reference rotational orientation can be associated with a fiducial point within the ultrasound image data, such that the ultrasound image can be oriented based on the determined tracking beam rotation angle.

Abstract: A controller-transmitter transmits acoustic energy through the body to an implanted acoustic receiver-stimulator. The receiver-stimulator converts the acoustic energy into electrical energy and delivers the electrical energy to tissue using an electrode assembly. The receiver-stimulator limits the output voltage delivered to the tissue to a predetermined maximum output voltage. In the presence of interfering acoustic energy sources output voltages are thereby limited prior to being delivered to the tissue. Furthermore, the controller-transmitter estimates the output voltage that is delivered to the tissue by the implanted receiver-stimulator. The controller-transmitter measures a query spike voltage resulting from the electrical energy delivered to the tissue by the receiver-stimulator, and computes a ratio of the predetermined maximum output voltage and a maximum query spike voltage. The maximum query spike voltage is computed by detecting a query spike voltage plateau.

Abstract: Delivery of an implantable wireless receiver-stimulator (R-S) into the heart using delivery catheter is described. R-S comprises a cathode and an anode and wirelessly receives and converts energy, such as acoustic ultrasound energy, to electrical energy to stimulate the heart. Conductive wires routed through the delivery system temporarily connect R-S electrodes to external monitor and pacing controller. R-S comprises a first temporary electrical connection from the catheter to the cathode, and a second temporary electrical connection from the catheter to the anode. Temporary electrical connections allow external monitoring of heart's electrical activity as sensed by R-S electrodes to determine tissue viability for excitation as well as to assess energy conversion efficiency.

Abstract: A wireless cardiac stimulation device comprising an implantable transmitter module housing a transmitter and a separately implantable battery module housing a battery for powering the transmitter and other device electronics via a subcutaneously routable electrical cable connecting the module is disclosed. The transmitter module contains a transmitter enclosure which comprises one or more ultrasound transducers. Having separate transmitter and battery modules allows implantation of the transmitter module closer to the target receiver implanted in tissue. A discrete battery module also enables easy replacement of the battery without disturbing the transmitter, which is highly desirable.

Abstract: A controller-transmitter transmits acoustic energy through the body to an implanted acoustic receiver-stimulator. The receiver-stimulator converts the acoustic energy into electrical energy and delivers the electrical energy to tissue using an electrode assembly. The receiver-stimulator limits the output voltage delivered to the tissue to a predetermined maximum output voltage. In the presence of interfering acoustic energy sources output voltages are thereby limited prior to being delivered to the tissue. Furthermore, the controller-transmitter estimates the output voltage that is delivered to the tissue by the implanted receiver-stimulator. The controller-transmitter measures a query spike voltage resulting from the electrical energy delivered to the tissue by the receiver-stimulator, and computes a ratio of the predetermined maximum output voltage and a maximum query spike voltage. The maximum query spike voltage is computed by detecting a query spike voltage plateau.

Abstract: Methods and systems for processing and/or superimposing a medical image of an anatomical body (e.g., a heart) with graphical information are provided. Reference elements and/or reference catheter are placed in contact with the anatomical body. A physical structure within a navigational coordinate system is located using the reference elements and/or reference catheter. An image reference within an image coordinate corresponding to the physical structure is located. Location of the image reference can be accomplished, e.g., by displaying the medical image and electronically marking the displayed image reference, or by automatically locating image data corresponding to the image reference. The navigational and image coordinate systems are then registered based on the location of the physical structure within the navigational coordinate system and the location of the image reference within the image coordinate system, which allows graphical information to be accurately merged with the medical image data.

Abstract: A wireless cardiac stimulation device is disclosed comprising a controller-transmitter, a receiver, and a stimulating electrode, wherein the stimulating electrode and the receiver are separately implantable at cardiac tissue locations of the heart and are connected by a local lead. Having separately implantable receiver and stimulating electrodes improves the efficiency of ultrasound mediated wireless stimulation by allowing the receiver to be placed optimally for reception efficiency, thereby resulting in longer battery life, and by allowing the stimulating electrode to be placed optimally for stimulus delivery. Another advantage is a reduced risk of embolization, since the receiver and stimulating electrode ensemble is attached at two locations of the heart wall, with the connecting local leads serving as a safety tether should either the receiver or the stimulating electrode become dislodged.

Abstract: Methods and systems are provided for generating graphical representations of orifices and vessels. One method comprises generating a representation of the surface (e.g., an endocardial surface) within a coordinate system, and laterally moving the distal end of an elongated probe within an orifice (e.g., a valve or a vessel ostium) associated with the surface. The method further comprises defining line segments within the coordinate system while the probe distal end is moved within the orifice, wherein each of the line segments represents the probe distal end. The method further comprises defining intersection points within the coordinate system, wherein each of the points represents an intersection of one of the line segments and the surface representation. Lastly, the method comprises graphically generating a representation of the orifice based on the intersection points, e.g., by forming the orifice representation around the intersection points.

Abstract: Methods and systems for graphically creating a representation of an anatomical structure, such as a heart, is provided. The distal end of an elongated probe is moved within the anatomical structure, and geometric shapes are defined within a coordinate system. By defining geometric shapes, such as spheres or circles, as the distal probe end is moved within the anatomical structure, the cavity within the anatomical structure can be represented. A representation of at least a portion of the anatomical structure can be graphically generated based on the geometric shapes, e.g., by determining a union of the geometric shapes and conforming the graphical representation around the union of the shapes. In the case of a heart, the union of the shapes will generally represent the blood volume within the heart, so that the graphical anatomical representation (which in this case will be a graphical representation of the endocardial surface of the heart) can be accurately conformed around the representative blood volume.

Abstract: A wireless cardiac stimulation device comprising an implantable transmitter module housing a transmitter and a separately implantable battery module housing a battery for powering the transmitter and other device electronics via a subcutaneously routable electrical cable connecting the module is disclosed. The transmitter module contains a transmitter enclosure which comprises one or more ultrasound transducers. Having separate transmitter and battery modules allows implantation of the transmitter module closer to the target receiver implanted in tissue. A discrete battery module also enables easy replacement of the battery without disturbing the transmitter, which is highly desirable.

Abstract: Visual electrode ablation systems are described herein which include a deployment catheter and an attached imaging hood deployable into an expanded configuration. In use, the imaging hood is placed against or adjacent to a region of tissue to be imaged in a body lumen that is normally filled with an opaque bodily fluid such as blood. A translucent or transparent fluid, such as saline, can be pumped into the imaging hood until the fluid displaces any blood, thereby leaving a clear region of tissue to be imaged via an imaging element in the deployment catheter. An electric current may be passed through the fluid such that it passes directly to the tissue region being imaged and the electrical energy is conducted through the fluid without the need for a separate ablation probe or instrument to ablate the tissue being viewed.

Abstract: Methods and systems for determining a proximity between a medical probe (such as, e.g., the tip of the medical probe) having an ultrasound transducer and a tissue surface, is provided. The ultrasound transducer is operated in a first resonant mode to transmit a first ultrasound signal that intersects the tissue surface to create a first reflected ultrasound signal, and operating in a second different resonant mode to transmit a second ultrasound signal that intersects the tissue surface to create a second reflected ultrasound signal. The first and second reflected ultrasound signals are received, e.g., by the ultrasound transducer, and a proximity between a portion of the medical probe and the tissue surface is determined based on the received first and second reflected ultrasound signals.

Abstract: Visual electrode ablation systems are described herein which include a deployment catheter and an attached imaging hood deployable into an expanded configuration. In use, the imaging hood is placed against or adjacent to a region of tissue to be imaged in a body lumen that is normally filled with an opaque bodily fluid such as blood. A translucent or transparent fluid, such as saline, can be pumped into the imaging hood until the fluid displaces any blood, thereby leaving a clear region of tissue to be imaged via an imaging element in the deployment catheter. An electric current may be passed through the fluid such that it passes directly to the tissue region being imaged and the electrical energy is conducted through the fluid without the need for a separate ablation probe or instrument to ablate the tissue being viewed.

Abstract: The present invention provides systems and methods for locating an imaging device within or outside of the body and for displaying a graphical representation of the imaging pattern associated with the imaging device within a global representation of the body. The imaging pattern characterizes the “field of vision” of the imaging device, and the graphical imaging pattern within the global representation of the body visually indicates the portion of the body that is being imaged by the imaging device in relation to the global representation of the body.

Abstract: Method and systems for optimizing acoustic energy transmission in implantable devices are disclosed. Transducer elements transmit acoustic locator signals towards a receiver assembly, and the receiver responds with a location signal. The location signal can reveal information related to the location of the receiver and the efficiency of the transmitted acoustic beam received by the receiver. This information enables the transmitter to target the receiver and optimize the acoustic energy transfer between the transmitter and the receiver. The energy can be used for therapeutic purposes, for example, stimulating tissue or for diagnostic purposes.

Abstract: A distance measuring system comprises first and second transducers, and an ultrasound ranging subsystem coupled to the first and second transducers for performing a plurality of distance measurements between the first and second transducers. The distance measurement system can have various applications, including medical applications, in which case, the first and second transducers can be mounted on a catheter. The distance measuring system further comprises a filter coupled to the ultrasound ranging subsystem for filtering ultrasound interference from the plurality of distance measurements (such as, e.g., eight), and outputting a distance based on the filtered distance measurements. The filter filters the ultrasound interference by selecting one of the plurality distance measurements, in which case, the outputted distance is the selected distance measurement.

Abstract: Methods and systems for determining a proximity between a medical probe (such as, e.g., the tip of the medical probe) having an ultrasound transducer and a tissue surface, is provided. The ultrasound transducer is operated in a first resonant mode to transmit a first ultrasound signal that intersects the tissue surface to create a first reflected ultrasound signal, and operating in a second different resonant mode to transmit a second ultrasound signal that intersects the tissue surface to create a second reflected ultrasound signal. The first and second reflected ultrasound signals are received, e.g., by the ultrasound transducer, and a proximity between a portion of the medical probe and the tissue surface is determined based on the received first and second reflected ultrasound signals.