WO98/52637 PCT/US98/10581 CATHETER WITH OBLIQUE LUMEN RELATED APPLICATIONS This application claims the benefit of U.S. 5 Provisional Patent Application no. 60/047,512, which is assigned to the assignee of the present patent application and is incorporated herein by reference. FIELD OF THE INVENTION 10 The present invention relates to catheters and catheterization techniques generally. BACKGROUND OF THE INVENTION Catheters used in interventional cardiology and 15 other applications are typically guided to a desired location in a human body, most commonly the left ventricle or other chamber of the heart, by first inserting a guide wire to the location and then sliding the catheter over the guide wire. The use of the guide 20 wire generally shortens the time required to get the catheter into the ventricle and eases the potentially dangerous passage through the aortic valve, when entering the left ventricle. Although it is also well known in the art to insert a catheter into the heart WO98/52637 PCT/US98/10581 -2 without the use of a guide wire, many cardiologists do not have the requisite level of skill or time to perform this operation, and are deterred by the risk of complications associated with such insertion. 5 Catheters for guide wire insertion are normally constructed with an open central lumen, running along the catheter's longitudinal axis, to receive the guide wire. This constructional constraint severely restricts the size and shape of functional elements within the 10 catheter and complicates the catheter's design. Such catheters cannot generally be manipulated within the heart after insertion thereinto. They are therefore substantially restricted to making measurements or performing interventional procedures only at the site 15 within the heart to which the guide wire has been inserted. SUMMARY OF THE INVENTION The present invention seeks to provide an improved 20 catheter and catheterization technique which overcome limitations imposed by the prior art. It is therefore an object of some aspects of the present invention to provide a catheter which is inserted into a body cavity, preferably a chamber of the WO 98/52637 PCTIUS98/10581 - 3 heart, using a guide wire, but may then be maneuvered with substantial freedom once inside the cavity. It is a further object of some aspects of the present invention to provide a catheter which is 5 inserted into the body along a guide wire, but which does not suffer from the structural and functional limitations imposed by having an open central lumen. In preferred embodiments of the present invention, a catheter for insertion into the heart has a lumen .0 passing therethrough for receiving a guide wire, wherein the lumen does not substantially coincide with the catheter's longitudinal axis. Preferably, the lumen runs obliquely through a distal portion of the catheter. Because the lumen is situated off the catheter's 15 longitudinal axis, a central portion of the catheter is left clear for placement of functional elements therein, preferably including a tip deflection mechanism for controllably maneuvering the distal portion of the catheter within the heart. 20 To use the catheter, a guide wire is inserted into the heart, typically into the left ventricle, using catheterization techniques known in the art. The catheter is then guided into the heart by sliding the lumen in a distal direction over the guide wire. Once WO98/52637 PCT/US98/10581 -4 the distal end of the catheter has reached its desired location in the heart, the guide wire is drawn back in a proximal direction, out of the heart, leaving the catheter in place. The distal end of the catheter may 5 then be maneuvered freely within the heart, preferably using the tip deflection mechanism. In some preferred embodiments of the present invention, the catheter includes a position sensor within the distal portion thereof. The position sensor 10 preferably comprises one or more coils, which generate signals responsive to an externally-applied magnetic field, as described in U.S. Patent 5,391,199 or in PCT publication WO96/05768 and incorporated herein by reference. Preferably, the catheter further includes 15 one or more electrodes on an outer surface of the distal portion, for measuring electrical activity and/or performing surgical procedures, such as electrosurgical ablation of the endocardium. Additionally or alternatively, the catheter may 20 include other sensors, known in the art, in or adjacent to its distal portion, for example, a pressure sensor or an ultrasound transducer. Likewise, the catheter may include other therapeutic elements, such as a waveguide for conveying radiation to the heart tissue, a channel WO98/52637 PCT/US98/10581 and/or tool for delivering medication to the tissue, or other elements known in the art. It will be appreciated that catheters in accordance with the principles of the present invention share with 5 guide wire-based catheters known in the art the advantage of rapid, safe and relatively easy insertion into the heart or other body cavity. Unlike catheters known in the art, however, catheters in accordance with the present invention may be maneuvered and navigated .0 freely inside the body. They may thus be used in a range of diagnostic and therapeutic modalities, for example, in mapping of electrophysiological, mechanical, electromechanical and/or hemodynamic aspects of cardiac function. .5 There is thus provided, in accordance with a preferred embodiment of the present invention, a flexible elongate probe having a longitudinal axis and a distal end, the probe enclosing and defining a lumen for receiving and riding over a guide wire, characterized in ?0 that the lumen is located other than along the longitudinal axis. There is further provided, in accordance with a preferred embodiment of the present invention, a catheterization kit including a guide wire and a WO98/52637 PCT/US98/10581 -6 flexible elongate probe having a longitudinal axis and a distal end, the probe enclosing and defining a lumen for receiving and riding over the guide wire, characterized in that the lumen is located other than along the 5 longitudinal axis. Preferably, the lumen passes through the probe obliquely with respect to the longitudinal axis, most preferably adjacent to the distal end thereof. Preferably, the probe includes a sensor, most 0 preferably a position sensor, adjacent to the distal end. Further preferably, the probe includes a deflection mechanism for deflecting the distal end of the probe. In a preferred embodiment, the probe includes an 5 electrode on an outer surface thereof. Preferably, the lumen passes through the electrode. In another preferred embodiment, the probe includes a therapeutic device, preferably an ablation electrode, through which the lumen preferably passes. 0 Preferably, the probe is a catheter for insertion into the heart of a subject. Additionally, in accordance with a preferred embodiment of the present invention, there is provided a catheterization technique including the steps of WO98/52637 PCT/US98/10581 -7 inserting a guide wire through a body passage and sliding a flexible elongate probe, having a longitudinal axis, along the guide wire, the guide wire passing through a lumen in the probe which is located other than 5 along the longitudinal axis thereof. Preferably, as the catheter slides over the guide wire, the portion of the guide wire inside the catheter is inclined obliquely with respect to the longitudinal axis. Further preferably, the guide wire passes through 0 an electrode fixed to an outer surface of the probe. Preferably, the guide wire is withdrawn, while leaving the probe in place within the body passage, and the probe is navigated within a body cavity communicating with the body passage after withdrawal of L5 the guide wire. Preferably, the body cavity is mapped using the probe. Alternatively or additionally, a therapeutic procedure is performed within the body cavity using the probe. 20 BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be understood and appreciated more fully from the following detailed WO98/52637 PCT/US98/10581 - 8 description, taken in conjunction with the drawings in which: Fig. 1 is a simplified illustration of a catheter and guide wire arrangement constructed and operative in 5 accordance with a preferred embodiment of the present invention; Fig. 2A is a sectional illustration of the catheter of Fig. 1; Fig. 2B is a sectional illustration of a catheter, t0 in accordance with an alternative preferred embodiment of the present invention; and Figs. 3A-3C are simplified pictorial illustrations of intravascular catheterization using the catheter and guide wire of Fig. 1, in accordance with a preferred 15 embodiment of the present invention. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Reference is now made to Fig. 1, which is a simplified pictorial illustration of a catheter 20 with 20 a guide wire 26, in accordance with a preferred embodiment of the present invention. Catheter 20 has a lumen 24 for receiving guide wire 26. The lumen passes through a distal portion 28 of the catheter obliquely to the catheter's longitudinal axis 22. Alternatively, a WO98/52637 PCT/US98/10581 - 9 lumen for receiving the guide wire may be provided at any other suitable location or orientation which is not central to distal portion 28, such that the majority of the portion is available for location therein of functional apparatus for use in therapeutic treatment and/or diagnosis of the patient. Such functional apparatus preferably includes elements for navigating catheter 20 within the body, as described below. Specifically, in the preferred D embodiment shown in Fig. 1, catheter 20 includes a position sensor 30 and a tip deflection mechanism 31. Position sensor 30 preferably comprises one or more magnetic-field-responsive coils, as described, for example, in the above-mentioned U.S. patent 5,391,199 or 5 PCT publication WO96/05768. Deflection mechanism 31 preferably comprises a resilient, bendable member, operated by a pull-wire 33, as described, for example, in PCT Patent Application PCT/IL98/00099, which is assigned to the assignee of the present patent 0 application and whose disclosure is incorporated herein by reference. Alternatively or additionally, catheter 20 may include and be navigated within the body by means of any suitable position sensor and/or tip deflection mechanism known in the art.
WO98/52637 PCTIUS98/10581 - 10 Fig. 2A is a schematic, sectional illustration of distal portion 28 of catheter 20. As shown in this figure, catheter 20 preferably has a central bore 32 for accommodating sensor 30, as well as a side bore 34 for 5 accepting deflection mechanism 31. These elements are preferably located proximally to oblique lumen 24. Further preferably, catheter 20 includes a ring electrode 29 on an outer surface of distal portion 28. Alternatively, the catheter may include a plurality of .0 mutually-spaced electrodes, as are known in the art. These electrodes are used in sensing and mapping electrical potentials within the heart, and may also be used in therapeutic treatment of cardiac arrhythmias, as described below. L5 Fig. 2B is a schematic, sectional illustration of distal portion 28 of catheter 20, in accordance with an alternative preferred embodiment of the present invention. In this embodiment, in place of electrode 29, the catheter includes a dome electrode 36 over the 20 distal portion and, preferably, a reference ring electrode 38 proximal thereto. The dome electrode provides enhanced functionality and ease of use, particularly in cardiac electrophysiological mapping and in RF ablation therapy. Oblique lumen 24 passes through WO98/52637 PCTIUS98/10581 - 11 dome electrode 36, which has a suitable opening 37 for this purpose. In other respects, the catheter of Fig. 2B is functionally and structurally similar to that shown in Fig 2A. 5 Additionally or alternatively, catheter 20 may include functional elements of other types useful in endocardiac diagnostics and therapy, for example, pressure and/or flow sensors, an optical fiber for delivery of laser radiation, or a longitudinal lumen for .0 suction and/or irrigation. It will be appreciated that catheters based on the principles of the present invention may generally include any type of functional or structural element that is used in catheters known in the art. L5 Figs. 3A-3C are simplified, schematic drawings showing intravascular catheterization of a subject 40 using catheter 20 and guide wire 26, in accordance with a preferred embodiment of the present invention. As shown in Fig. 3A, guide wire 26 is inserted ?0 percutaneously, preferably via femoral artery 42 of subject 40, and is directed into the subject's heart 44, typically into left ventricle 46, as in conventional intravascular catheterization. Then, as shown in Fig. 3B, catheter 20 is passed along wire 26 into the heart.
WO98/52637 PCT/US98/10581 - 12 Alternatively, guide wire 26 may be used to insert catheter 20 into any other desired chamber of the heart, or to another suitable site in the subject's body. Finally, as shown in Fig. 3C, guide wire 26 is 5 withdrawn, leaving catheter 20 freely maneuverable within ventricle 46. By using deflection mechanism 31 and sensor 30, a physician can navigate distal portion 28 of catheter 20 to substantially any desired location within the ventricle. This navigation capability is 0 particularly useful in mapping electrical and/or mechanical activity within the heart, as is known in the art and described, for example, in U.S. patent 5,568,809, which is incorporated herein by reference. Similarly, catheter 20 may be used in therapeutic 5 treatment of cardiac arrhythmias, preferably using electrode 29 to ablate areas of the endocardium by applying RF energy thereto, as is known in the art. Most preferably, such ablation is combined with mapping the heart's electrical activity, as described, for 0 example, in U.S. patent 5,391,199, which is incorporated herein by reference. Likewise, catheter 20 may be adapted for use in substantially any diagnostic or therapeutic procedure for which catheters known in the art are used, with the WO98/52637 PCTIUS98/10581 - 13 advantage that catheter 20 can generally be inserted into the heart with considerably greater speed, ease and safety than non-wire-guided catheters. For example, the catheter may include an optical waveguide, coupled to a source of laser energy at the catheter's proximal end, for use in percutaneous myocardial revascularization (PMR) therapy, as described in PCT patent application PCT/IL97/00011, filed January 14, 1997, which is incorporated herein by reference, or as is otherwise 0 known in the art. Although the above preferred embodiments have been described with reference to cardiac catheterization, and specifically catheterization of left ventricle 46, it will be appreciated that catheters, endoscopes and other 5 types of flexible medical probes may be produced and operated in accordance with the principles of the present invention for insertion into substantially any part of the heart, vasculature and other body cavities. It will further be appreciated by persons skilled 0 in the art that the present invention is not limited to what has been particularly shown and described hereinabove. Rather the scope of the present invention includes combinations and subcombinations of various WO98/52637 PCT/US98/10581 - 14 features and elements described and shown herein, as well as obvious variations and extensions thereof.