Patent Application
20180228393
This invention relates to sensors for use with electrophysiologic (EP) catheters, guiding sheaths and related devices for mapping and/or ablation of locations within a patient, such as the heart, in particular, to construction techniques for forming components including electrodes and navigation coils.
Mapping of electrical potentials in the heart is now commonly performed, using cardiac catheters comprising electrophysiological sensors for mapping the electrical activity of the heart. Typically, time-varying electrical potentials in the endocardium are sensed and recorded as a function of position inside the heart, and then used to map a local electrogram or local activation time. Activation time differs from point to point in the endocardium due to the time required for conduction of electrical impulses through the heart muscle. The direction of this electrical conduction at any point in the heart is conventionally represented by an activation vector, which is normal to an isoelectric activation front, both of which may be derived from a map of activation time. The rate of propagation of the activation front through any point in the endocardium may be represented as a velocity vector. Mapping the activation front and conduction fields aids the physician in identifying and diagnosing abnormalities, such as ventricular and atrial tachycardia and ventricular and atrial fibrillation, which may result from areas of impaired electrical propagation in the heart tissue.
Localized defects in the heart's conduction of activation signals may be identified by observing phenomena such as multiple activation fronts, abnormal concentrations of activation vectors, or changes in the velocity vector or deviation of the vector from normal values. Examples of such defects include re-entrant areas, which may be associated with signal patterns known as complex fractionated electrograms. Once a defect is located by such mapping, it may be ablated (if it is functioning abnormally) or otherwise treated so as to restore the normal function of the heart insofar as is possible. As an illustration, cardiac arrhythmias including atrial fibrillation, may occur when regions of cardiac tissue abnormally conduct electric signals to adjacent tissue, thereby disrupting the normal cardiac cycle and causing asynchronous rhythm. Procedures for treating arrhythmia include disrupting the origin of the signals causing the arrhythmia, as well as disrupting the conducting pathway for such signals, such as by forming lesions to isolate the aberrant portion. Thus, by selectively ablating cardiac tissue by application of energy via a catheter, it is sometimes possible to cease or modify the propagation of unwanted electrical signals from one portion of the heart to another. The ablation process destroys the unwanted electrical pathways by formation of non-conducting lesions.
Accordingly, a suitable EP catheter may have one or more sensor electrodes for measuring electrical signals and/or delivering ablation energy. Each electrode requires its own lead to conduct the received electrical signals through the catheter for recording and processing by instrumentation coupled to the catheter or to transmit the energy for ablation. Further, the EP catheter may also employ one or more location sensors to help track the position of the catheter and determine placement of the electrodes within the patient. Thus, a number of leads may also be required for the location sensors. The multiplicity of leads are typically routed through a lumen in the polymeric tube forming the catheter and must be connected to their respective electrode or location sensor, which represents a significant investment of time and labor as well as being subject to a high failure rate. For example, each lead is fished out through an opening made in the catheter wall, stripped of insulation and welded or soldered to the component and the process is repeated. Moreover, the typical materials used for electrodes, such as platinum or iridium, contribute significantly to the overall cost of the catheter.
Accordingly, it would be desirable to provide a sensor construction that reduces or avoids the use of dedicated electrode materials. Similarly, it would be desirable to provide a more reliable connection between the leads and the components. Further, it would be desirable to deploy such components on a variety of electrophysiologic devices, including catheters, guiding sheaths and others. The techniques of this disclosure as described in the following materials satisfy these and other needs.
The present disclosure is directed to an electrophysiologic device with an elongated body having proximal and distal ends and at least one lumen therethrough and at least one coil formed around a distal portion of the catheter body, wherein the coil may be a plurality of helical wraps of a continuous wire that extends to the proximal end of the elongated body through the lumen.
In one aspect, the electrophysiologic device may be an electrophysiologic catheter and the at least one coil may be an electrode or a location sensor.
In one aspect, the electrophysiologic device may be a guiding sheath having an inner lumen configured to coaxially receive a catheter and the at least one coil may be an electrode or a location sensor. The guiding sheath may be deflectable
In one aspect, the at least one coil may be configured as a ring electrode. For example, the at least one coil may have a longitudinal length in the range of approximately 1 mm to 4 mm. A plurality of coils may be provided, wherein each coil is configured as a ring electrode.
In one aspect, the at least one coil may be configured as a location sensor and/or an additional coil may be configured as a location sensor.
This disclosure also includes a method for constructing an electrophysiological device. The method may involve providing an elongated body having proximal and distal ends and at least one lumen therethrough, routing a continuous wire from the proximal end of the elongated body through the lumen to a distal location and forming a plurality of wraps around the elongated body at the distal location to form a coil.
In one aspect, the wire may be routed through an opening in a side wall of the elongated body at the distal location, wherein the opening communicates with the lumen, and the opening may be sealed.
In one aspect, insulation may be removed from a distal portion of the wire that extends from the opening. The coil may be configured to function as a ring electrode.
In one aspect, the coil may be configured to function as a location sensor.
In one aspect, a plurality of coils may be formed at distinct distal locations on the elongated body. For example, at least one of the plurality of coils may be configured to function as a ring electrode and at least another of the plurality of coils may be configured to function as a location sensor.
The disclosure also includes a method for treatment that may involve providing a guiding sheath having an elongated body with proximal and distal ends and at least one lumen therethrough and at least one coil formed around a distal portion of the elongated body, wherein the coil comprises a plurality of helical wraps of a continuous wire that extends to the proximal end of the elongated body through the lumen, advancing the distal end of the guiding sheath with the at least one coil to a desired region within a patient and communicating electrical signals with the at least one coil.
In one aspect, communicating electrical signals with the at least one coil may occur with a catheter coaxially disposed within the guiding sheath.
In one aspect, the elongated body may be deflected while advancing the guiding sheath
Further features and advantages will become apparent from the following and more particular description of the preferred embodiments of the disclosure, as illustrated in the accompanying drawings, and in which like referenced characters generally refer to the same parts or elements throughout the views, and in which:
At the outset, it is to be understood that this disclosure is not limited to particularly exemplified materials, architectures, routines, methods or structures as such may vary. Thus, although a number of such options, similar or equivalent to those described herein, can be used in the practice or embodiments of this disclosure, the preferred materials and methods are described herein.
It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments of this disclosure only and is not intended to be limiting.
The detailed description set forth below in connection with the appended drawings is intended as a description of exemplary embodiments of the present disclosure and is not intended to represent the only exemplary embodiments in which the present disclosure can be practiced. The term “exemplary” used throughout this description means “serving as an example, instance, or illustration,” and should not necessarily be construed as preferred or advantageous over other exemplary embodiments. The detailed description includes specific details for the purpose of providing a thorough understanding of the exemplary embodiments of the specification. It will be apparent to those skilled in the art that the exemplary embodiments of the specification may be practiced without these specific details. In some instances, well known structures and devices are shown in block diagram form in order to avoid obscuring the novelty of the exemplary embodiments presented herein.
For purposes of convenience and clarity only, directional terms, such as top, bottom, left, right, up, down, over, above, below, beneath, rear, back, and front, may be used with respect to the accompanying drawings. These and similar directional terms should not be construed to limit the scope of the disclosure in any manner
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one having ordinary skill in the art to which the disclosure pertains.
Finally, as used in this specification and the appended claims, the singular forms “a, “an” and “the” include plural referents unless the content clearly dictates otherwise.
As noted above, certain types of electrical activity within a heart chamber are not cyclical. Examples include arterial flutter or arterial fibrillation, and ventricular tachycardia originating in scars in the wall of the ventricle that have resulted from infarcts. Such electrical activity is random from beat to beat. To analyze or ‘map’ this type of electrical activity, it is desirable to provide an electrophysiologic catheter with one or more electrodes to measure the electrical signals. Further, RF energy may be delivered to selected treatment areas for ablation based therapies, including for example, isolation of a source of irregular electrical signals by blocking electrical conduction. Correspondingly, one or more electrodes may be used to deliver ablation energy. Still further, the catheter may employ one or more location sensors to help visualize or otherwise determine the relative position of the catheter within the patient. According to the techniques of this disclosure, one or more of the electrodes and/or location sensors may be formed from a coil of wire wound around the elongated body of the electrophysiologic catheter. In some embodiments, the electrophysiologic catheter may be advanced through a guiding sheath to facilitate positioning the electrodes at a desired position within the patient. Notably, the positioning of the electrophysiologic catheter within a guiding sheath may block one or more electrodes or location sensor of the catheter depending on the relative longitudinal positioning of the catheter within the guiding sheath, hindering visualization or otherwise reducing the effectiveness of recording or delivering electrical signals. As such, one or more of the electrodes and/or location sensors may also be formed from a coil of wire wound around the elongated body of the guiding sheath. Deploying electrodes and/or location sensors on the guiding sheath permits their use regardless of the relative position of the catheter.
To provide a context for the disclosure, an exemplary catheter having a lasso-shaped electrode assembly coaxially disposed within a guiding sheath is shown schematically in
Lasso electrode assembly 16 may be of a known fixed length, and comprises material that preferably is twistable but not stretchable when subjected to typical forces. In one aspect, lasso electrode assembly 16 may be sufficiently resilient so as to assume a predetermined, curved form, when no force is applied thereto, and to be deflected from the predetermined curved form when a force is applied thereto. For example, lasso electrode assembly 16 may have an elasticity that is generally constant over at least a portion of its length, for example, because of internal reinforcement of the curved section with a resilient longitudinal member, such as a shape memory material (e.g. a nickel-titanium alloy) as is known in the art. Lasso electrode assembly 16 may form a complete or partial lasso, i.e., as a preformed arcuate structure, which typically subtends between 180° and 360°. In one aspect, lasso electrode assembly 16 may form a substantially complete circle so as to allow mapping and/or ablation around or substantially around the circumference of a vessel. The radius of curvature of lasso electrode assembly 16, when unconstrained, may be typically between 7.5 mm and 15 mm. Because the arc structure is resilient and, possibly, slightly helical, when lasso electrode assembly 16 is positioned in the heart (against the ostium of pulmonary vein 50, for example), it will press against the heart tissue over the entire length of the arc, thus facilitating good tissue contact.
Lasso electrode assembly 16 may have one or more electrodes 18, configured as ring electrodes, and one or more location sensors 20. Conventionally, ring electrodes are rings formed from a suitable material, such as platinum or iridium, and positioned at various intervals along the length of a distal portion of elongated body 12. The ring electrodes are electrically connected, via electrode lead wires which extend through a lumen in the catheter, to electrical instruments, e.g., a monitor, stimulator or source of energy, e.g., RF energy, for ablation. Such conventional ring electrodes are connected to their lead wire by drawing the wire out of a lumen through an exit hole that extends from the lumen to the side surface of the catheter body. As noted above, the distal end of the electrode lead wire may be stripped of any non-conductive coating or insulation and then welded or soldered onto the inner surface of a ring electrode. The ring electrode is then slipped over the tip shaft to a position directly over the exit hole while drawing the electrode lead wire back into the lumen. The ring electrode is then secured in place, e.g., by swaging or by the application of an appropriate adhesive. A resin, e.g., polyurethane resin, is often applied to the margins or edges of the ring electrode to assure a smooth transition between the outer circumferential surface of the ring electrode and the outer circumferential surface of the catheter shaft. In contrast, one or more of electrodes 18 and location sensors 20 may be formed from a continuous length of wire extending from a proximal end and helically wrapped to form a coil around a distal portion of elongated body 12 as described in further detail below.
Further,
According to the techniques of this disclosure, the need to use a separate metallic component to form the ring electrode may be avoided. As schematically shown in
Initially, lead wire 36 may be routed through lumen 38 of elongated body 12 with respect to electrophysiologic catheter 10 as shown in
The number of wraps may be selected to form coil 34 with properties as warranted to function as an electrode 18 or as a location sensor 20 according to the description below. Notably, to form electrode 18, any insulation may be stripped from the distal portion of lead wire 36 so that adjacent turns are electrically coupled. Alternatively, the insulation may be left intact when forming location sensor 20, so that coil 34 may generate or respond to a magnetic field for use in an impedance-based positioning system as described below. As indicated in
As noted, the number of wraps used in coil 34 may be tailored to provide either an electrode 18 or a location sensor 20 having desired properties. For example, the number of wraps of lead wire 36 used to form coil 34 having sufficient surface area when functioning as electrode 18. In one embodiment, longitudinal length of coil 34 may be in the range of approximately 1 mm to 4 mm and it will be appreciated that the number of wraps depends at least in part on the diameter of lead wire 36. The desired characteristics of coil 34 may also be adjusted depending on whether the resulting electrode 18 is intended to function as a diagnostic electrode for measuring electrical signals, to function as an ablation electrode for delivering energy, or to function as both. Any suitable number of electrodes 18 may be formed by separate coils 34, and they may be distributed in a desired position along the length of elongated body 12. Further, electrodes 18 may be configured as electrode pairs to function as bipolar electrodes, such that they may be constructed from two coils 34. Therefore, by following the techniques of this disclosure, coil 34 may be formed as electrode 18 in a manner that permits opening 40 to be sealed and its integrity confirmed as compared to conventional methods for mounting ring electrodes, which require the lead wire to be drawn back into the lumen the ring electrode is position, preventing sealing and inspection of the opening. Further, since coil 34 is formed from separate wraps of lead wire 36, it may accommodate bends and other deformations in elongated body 12 more readily than a conventional monolithic ring electrode. Alternatively or in addition, one or more electrodes 18 may be formed from coils 34 around elongated body 26 of guiding sheath 22.
Similarly, a suitable number of wraps may be formed when coil 34 is intended to function as location sensor 20. As will be appreciated, coil 34 may be used with a system for generating three-dimensional position information regarding catheter. For example, coil 34 may be configured to generate electrical signals in response to an externally applied magnetic field, such as by responding to specific frequency of the field. Exemplary details regarding certain embodiments of location sensors 20 may be found in commonly-assigned U.S. Pat. No. 8,792,296, entitled “Catheter With Single Axial Sensors,” which is hereby incorporated by reference in its entirety. As with electrodes 18, one or more location sensors 20 formed from coils 34 may be positioned as desired on elongated body 12 of catheter 10, on elongated body 26 of guiding sheath 22, or both.
The elongated body 12 is flexible, i.e., bendable, but substantially non-compressible along its length. The elongated body 12 can be of any suitable construction and made of any suitable material. One construction comprises an outer wall made of polyurethane or PEBAX® (polyether block amide). The outer wall comprises an imbedded braided mesh of stainless steel or the like to increase torsional stiffness of the elongated body 12 so that, when the control handle 14 is rotated, the distal end of the elongated body will rotate in a corresponding manner. In other embodiments, an inner stiffening tube may be coaxially disposed within a lumen of elongated body 12, forming an annular lumen 38 through which lead wires 36 for electrodes 18 and/or location sensors 20 may be routed. In some embodiments, elongated body 12 may be steerable and/or deflectable using any suitable technique, which are known to those of ordinary skill in the art. The outer diameter of the elongated body 12 is not critical, but generally should be as small as possible and may be no more than about 10 french depending on the desired application. For example, for use in the mapping and ablation for isolation of a pulmonary vein, elongated body may have an outer diameter of about 7 to 7.5 french. Likewise the thickness of the outer wall is not critical, but may be thin enough so that the central lumen can accommodate lead wires 24 and any other necessary components. If desired, the inner surface of the outer wall is lined with a stiffening tube (not shown) to provide improved torsional stability. An example of a elongated body construction suitable for use in connection with the present invention is described and depicted in U.S. Pat. No. 6,064,905, the entire disclosure of which is incorporated herein by reference.
In one aspect, an electrophysiologist may introduce guiding sheath 22, a guidewire and a dilator into the patient, as is generally known in the art. As an example, guiding sheath 22 may be similar to a PREFACE™ Braided Guiding Sheath (commercially available from Biosense Webster, Inc., Diamond Bar, Calif.). The guidewire is inserted, the dilator is removed, and catheter 10 is introduced through the guiding sheath 22. In one exemplary procedure as depicted in
As will be appreciated, lasso electrode assembly 16 may be deflected into a straightened configuration and constrained within guiding sheath 22 to allow catheter 10 to be passed through the patient's vasculature to the desired location. Once the distal end of the catheter reaches the desired location, e.g., the left atrium, guiding sheath 22 is withdrawn to expose the lasso electrode assembly 16, where it recoils into its arcuate configuration. With the lasso electrode assembly 16 then positioned in the ostium of a pulmonary vein (PV), electrodes 18 contact the ostial tissue and may be used to map electrical signals in this area. In other embodiment, different electrode configuration may be used to access other areas of a patient's anatomy as desired.
To help illustrate use of catheter 10 and guiding sheath 22,
Further, the processing unit 60 may also receive signals from location sensors 20 (not shown in this view). As noted, the sensor(s) may each comprise a magnetic-field-responsive coil or a plurality of such coils, each formed by coil 34. Using a plurality of coils enables six-dimensional position and orientation coordinates to be determined. The sensors may therefore generate electrical position signals in response to the magnetic fields from external coils, thereby enabling processor 60 to determine the position, (e.g., the location and orientation) of the distal end of catheter 10 and/or guiding sheath 22 within the heart cavity. The electrophysiologist may then view the position of the lasso electrode assembly 16 on an image the patient's heart on the display 62. By way of example, this method of position sensing may be implemented using the CARTO™ system, produced by Biosense Webster Inc. (Diamond Bar, Calif.) and is described in detail in U.S. Pat. Nos. 5,391,199, 6,690,963, 6,484,118, 6,239,724, 6,618,612 and 6,332,089, in PCT Patent Publication WO 96/05768, and in U.S. Patent Application Publications 2002/0065455 A1, 2003/0120150 A1 and 2004/0068178 A1, whose disclosures are all incorporated herein by reference. As will be appreciated, other location sensing techniques may also be employed. The coordinates of location sensor 20 may be determined and, with other known information pertaining to the configuration of lasso electrode assembly 16, used to find the positions of each of the electrodes 18.
The preceding description has been presented with reference to presently disclosed embodiments of the invention. Workers skilled in the art and technology to which this invention pertains will appreciate that alterations and changes in the described structure may be practiced without meaningfully departing from the principal, spirit and scope of this invention. As understood by one of ordinary skill in the art, the drawings are not necessarily to scale. Accordingly, the foregoing description should not be read as pertaining only to the precise structures described and illustrated in the accompanying drawings, but rather should be read consistent with and as support to the following claims which are to have their fullest and fair scope.
