Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
2001-07-10
2004-04-06
Ruhl, Dennis (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C600S450000, C600S462000, C600S466000, C600S467000
Reexamination Certificate
active
06716166
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to systems and methods for three-dimensional mapping and reconstruction, and specifically to mapping and reconstruction of the interior of body organs, such as the heart.
BACKGROUND OF THE INVENTION
Methods for three-dimensional geometrical mapping and reconstruction of the endocardial surface are known in the art. For example, U.S. Pat. No. 5,738,096, whose disclosure is incorporated herein by reference, describes methods for mapping the endocardium based on bringing a probe into contact with multiple locations on a wall of the heart, and determining position coordinates of the probe at each of the locations. The position coordinates are combined to form a map of at least a portion of the heart. These methods are effective and accurate, but they require substantial time and skill to carry them out.
A variety of methods have been developed for non-contact reconstruction of the endocardial surface using intracardial ultrasonic imaging. These methods typically use a catheter with a built-in, miniaturized ultrasonic imaging array or scanner. For example, PCT patent publication WO00/19908, whose disclosure is incorporated herein by reference, describes a steerable transducer array for intracardial ultrasonic imaging. The array forms an ultrasonic beam, which is steered in a desired direction by an active aperture. Similarly, U.S. Pat. No. 6,004,269, whose disclosure is also incorporated herein by reference, describes an acoustic imaging system based on an ultrasound device that is incorporated into a catheter. The ultrasound device directs ultrasonic signals toward an internal structure in the heart to create an ultrasonic image.
Further examples of intracardial ultrasonic imaging are presented in U.S. Pat. NO. 5,848,969 and in PCT patent publication WO98/18388, whose disclosures are incorporated herein by reference. These publications describe systems and methods for visualizing interior tissue regions using expandable imaging structures. The structures assume an expanded geometry once inside the heart, which stabilizes an associated imaging probe or array.
U.S. Pat. No. 5,797,849 and PCT patent publication WO99/58055, whose disclosures are also incorporated herein by reference, describe methods for carrying out medical procedures using a three-dimensional tracking and imaging system. The position of a catheter or other probe inside the body is tracked, and its location relative to its immediate surroundings is displayed to improve a physician's ability to precisely position it. Various procedures using such a probe are described in these publications. One such procedure is ultrasonic imaging, using an ultrasound imaging head with transducers held outside the body to image an area inside the body in which a probe with a position sensor is located.
Various methods are known in the art for enhancing ultrasonic images and for extracting information, such as three-dimensional contours, from such images. These methods typically combine information from multiple two-dimensional images to define three-dimensional features. For example, PCT patent publication WO99/55233, whose disclosure is incorporated herein by reference, describes a method for defining a three-dimensional surface of at least a portion of a patient's heart using a plurality of images in different planes. The images are made using an ultrasound transducer at known positions and orientations outside the patient's body. Anatomical landmarks are manually identified in the plurality of images. Other methods of contour extraction and three-dimensional modeling using ultrasonic images are described in European patent application EP 0 961 135 and in Japanese patent application JP 9-285465 whose disclosures are also incorporated herein by reference. As another example, PCT patent publication WO98/46139, whose disclosure is incorporated herein by reference, describes a method for combining Doppler and B-mode ultrasonic image signals into a single image using a modulated nonlinear mapping function.
SUMMARY OF THE INVENTION
It is an object of some aspects of the present invention to provide improved methods and apparatus for three-dimensional mapping and geometrical reconstruction of body cavities, and particularly of chambers of the heart.
In preferred embodiments of the present invention, a cardiac catheter comprises a plurality of acoustic transducers distributed longitudinally along a distal portion of the catheter. The transducers are actuated individually, in sequence, to emit acoustic waves, preferably ultrasonic waves, while the catheter is inside a chamber of the heart. The acoustic waves are reflected from the endocardial surface of the cavity and are received by the transducers. Processing circuitry, coupled to the transducers, determines the times of flight of the received acoustic waves, thus providing a measurement of the distance from each of the transducers to a point or area on the endocardial surface opposite the transducer. The distance measurements are combined to reconstruct the three-dimensional shape of the surface, which is preferably displayed in the form of a geometrical map.
Preferred embodiments of the present invention thus enable the entire endocardial surface to be mapped rapidly, typically within a single heart beat. This rapid mapping can be achieved because the acoustic waves are used to measure three-dimensional distances directly, rather than attempting to image the heart and then extract geometrical information from the images as in methods known in the art. The distance measurements are facilitated by the unique design of the catheter, wherein the transducers are distributed longitudinally along the catheter, instead of being concentrated in a phased array or other imaging configuration. Preferred embodiments of the present invention also avoid the need for physical contact between the catheter and the endocardial surface during measurement.
In some preferred embodiments of the present invention, the catheter comprises one or more position sensors, which are used to determine position and orientation coordinates of the catheter within the heart. Using the position sensors in conjunction with the acoustic measurements allows the reconstructed three-dimensional shape of the surface to be located and oriented in space. It also enables multiple measurements to be taken at different positions within the heart in order to enhance the accuracy of the reconstruction. Preferably, the position sensors comprise one or more miniature coils, which are used to determine position and orientation coordinates by transmitting or receiving electromagnetic waves, as described, for example, in PCT patent publication WO96/05768 or in U.S. Pat. No. 5,391,199, which are incorporated herein by reference. Alternatively, the acoustic transducers on the catheter also serve as position sensors, by receiving acoustic waves transmitted from a plurality of acoustic transducers at fixed positions outside the body, or by transmitting acoustic waves to these external transducers. The times of flight of these waves are used to determine the position and orientation of the catheter. Further alternatively, other types of position sensing systems, as are known in the art, may be used.
In further preferred embodiments of the present invention, the catheter comprises a plurality of electrodes in addition to the acoustic transducers, and is used for electrical, as well as geometrical, mapping of the heart. Preferably, the electrical mapping is performed rapidly using an array of non-contact electrodes, most preferably as described in a U.S. patent application entitled “Rapid Mapping of Electrical Activity in the Heart,” filed Jun. 21, 2000 (applicant's docket no. BIO 97 US), which is assigned to the assignee of the present patent application and is incorporated herein by reference. The electrical and geometrical maps are registered to provide an integrated view of mechanical and electrical properties of the heart.
In some preferred embodiments of the p
Biosense Inc.
Capezzuto Louis J.
Jung William C.
Ruhl Dennis
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