Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
1999-09-22
2001-10-02
Lateef, Marvin M. (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C600S424000
Reexamination Certificate
active
06298257
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to cardiac procedures, and in particular to magnetically assisted methods for conducting cardiac procedures, and a system for conducting cardiac procedures.
BACKGROUND OF THE INVENTION
Many cardiac procedures employ catheters and other similar devices that are manipulated into the chambers of the heart. Electrophysiology (EP) is a discipline in which catheters are fed into the open chambers of the heart, generally gaining access via the great veins. The distal section of the catheter is manually manipulated within the heart by tactile control of the proximal catheter section, which can be up to four feet or more from the distal section, often in the groin area of the patient. Precise manipulation of the catheters is desired to record the electrical signals emanating from the endocardial surfaces. It is desirable to drag the catheters along curved paths, maintaining contact with the inside or endocardial surface of the heart chambers, even as the heart muscle constricts and relaxes. It is further most desirable to identify the anatomical features of the heart which are in contact with the catheter, and to record their location in space. It is then often desirable to return to a specific location to either re-record the electrical signal or to apply energy through the catheter to ablate tissue which is involved in the generation of abnormal electrical signals or arrhythmias.
Precise manipulation of the distal end of recording and ablation catheters from the proximal end is generally difficult and often impossible because of the squeezing motions of the heart, the convoluted anatomy of the heart chambers (especially when the catheter must pass through one chamber to access an adjacent chamber), and the presence of anatomical structures such as cords and tribiculae.
The catheters presently used for these procedures are usually navigated using a mechanically navigated guide wire, or arc themselves directly mechanically navigated. These mechanically navigable catheters are difficult to accurately control, and become increasingly so as the catheter twists and turns. One difficulty with presently available cardiac catheters is that it is difficult to determine when the catheter is in contact with the surface of the heart. Moreover, even when the catheter is in contact with the surface of the heart, it is not possible to determine the contact pressure.
SUMMARY OF THE INVENTION
The present invention relates to an improved method of and system for navigating catheters within the heart and surrounding blood vessels, employing an externally applied magnetic field. This not only facilitates navigation within the heart and blood vessels, but also allows the catheter to contact the surface of the heart with certainty, and even with a controllable predetermined force. Through the use of localization techniques, such as magnetic localization or RF localization, the catheter can be precisely located in the body to thereby locate the point where the catheter is touching, for structural and physiological mapping, and to facilitate returning the catheter to a previously identified site. Moreover by providing the appropriate control of the magnetic field generating device and advancement of the catheter, the catheter can be automatically navigated to respected points on the surface of the heart for diagnostic or treatment purposes. The catheter can also be automatically navigated to a plurality of points for structural and/or physiological mapping.
Broadly, magnetically controlled EP catheters are disclosed in pending utility patent application Ser. No. 09/151,615, filed Sept. 11, 1998, entitled “Magnetically Navigable Telescoping Catheter And Method Of Navigating Telescoping Catheter”, and pending U.S. patent application Ser. No. 09/311,686 filed May 13, 1999, entitled “Magnetic Medical Device and Method of Navigating Magnetic Medical Devices with Magnetic Fields and Gradients” incorporated herein by reference. The present invention is directed to systems that control intracardiac catheters, and features of such systems which are unique to the field of cardiology.
Perhaps the simplest implementation of a system for navigating magnetic catheters over the endocardial surfaces involves bi-planer fluoroscopic imaging of the catheter, and point-and-click direction of the catheter tip, as described in U.S. patent application Ser. No. 09/020,798, filed Feb. 9, 1998, entitled “Device and Method for Specifying Magnetic Field for Surgical Applications” in the context of endovascular navigation. The physician uses a joystick to specify the location of the catheter tip and desired direction of motion on each of the two bi-planer images. The present invention improves upon this by providing a method and system that not only permits navigation, but provides the ability to positively contact the surface, and do so with a specified force, or at least a force between specified minimum and maximum values. This is important for insuring that that procedures employing the catheter are properly carried out.
A second aspect of the invention is the coupling of localization of the distal end of the medical device with the magnetic navigation to provide information for automation of the navigation of the medical device. This allows the physician to specify a point on the bi-plane images that he desires the catheter tip to touch, and the computer generates the necessary magnet commands via the known catheter tip location and the desired or specified location. This becomes useful in electrophysiology because in addition to automatically positioning the medical device where the physician specifies, the system positively contacts the device with the surface of the heart, and can do so with a specified force. There are many possibilities for locating the catheter tip, including the use of beams of electromagnetic or ultrasound energy in addition to the X-ray beams. Methods for using the magnetic surgery source fields for localization have been disclosed U.S. utility patent application Ser. No. 09/020,942, filed Feb. 9, 1998, entitled “Method and Device for Locating Magnetic Implant by Source Field”, as have the use of AC magnetic fields as disclosed in U.S. Pat. No. 4,173,228, for Catheter Locating Device, both of which are incorporated herein by reference. Other suitable localization methods and apparatus are disclosed in U.S. Pat. No. 5,752,513, issued May 19, 1998, for “Method and Apparatus for Determining Position of Object”; U.S. Pat. No. 5,729,129, issued Mar. 17, 1998, for “Magnetic Location System with Feedback Adjustment of Magnetic Field Generator”; U.S. Pat. No. 5,558,091, issued Sep. 24, 1996, for “Magnetic Determination of Position and Orientation”; and U.S. Pat. No. 5,833,608, issued Nov. 10, 1998, for “Magnetic Determination of Position and Orientation”, each of which is incorporated herein by reference.
According to a third aspect of this invention preoperative images of the heart are made and used in the navigation. The use of preoperative images for magnetic navigation is disclosed in U.S. Pat. No. 4,869,247, issued Sep. 26, 1989, entitled “Video Tumor Fighting System” and in U.S. Pat. No. 5,125,888, issued on Jun. 30, 1992, entitled “Magnetic Stereotactic System for Treatment Delivery”, incorporated herein by reference. According to the present invention, a pre-operative image, for example an MRI or CT image, is taken with a reference catheter in place, or using an anatomical feature such as a rib or the sternum as a reference marker. A dynamic, i.e., moving pre-operative image of the heart can then be displayed during the procedure, with the heart motions referenced to the ECG signal to properly align the motion with the patient's cardiac cycle. The reference features are continuously localized via bi-planer image processing or localization sensors to place the pre-operative image in proper perspective, and allow correct visualization of the catheters on the image. With all catheters localized in space, the pre-operative image can be rotated to desired imag
Blume Walter M.
Hall Andrew F.
Hastings Roger N.
Harness & Dickey & Pierce P.L.C.
Lateef Marvin M.
Mantis Mercader Eleni
Sterotaxis, Inc.
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