Patent Application
20200001054
The subject matter disclosed herein relates to electrophysiologic catheters, particularly those capable of ablating cardiac tissue via electrodes disposed on a balloon surface.
Ablation of cardiac tissue has been used to treat cardiac arrhythmias. Ablative energies are typically provided to cardiac tissue by a tip portion, which can deliver ablative energy alongside the tissue to be ablated. Some of these catheters administer ablative energy from various electrodes disposed on or incorporated into three-dimensional structures, e.g., wire baskets and balloons.
A balloon of a balloon catheter must be able to withstand fatigue to its componentry caused by multiple cycles of repeat motions, such as deployment from a lumen of the catheter, expanding the balloon, collapsing the balloon, and withdrawal of the balloon back into the lumen. Such a catheter balloon may comprise a membrane including a proximal end and a distal end. A plurality of substrates, each including a plurality of tails, may be disposed about the membrane. A reinforcement may be disposed over at least some of the plurality of tails and attached to the membrane. The reinforcement may comprise a portion of an unassembled catheter balloon. Alternatively, or additionally, the reinforcement may have a horn-like shape. In any of the embodiments, the membrane may comprise polyethylene terephthalate, polyurethane, Pellethane, or PEBAX.
Further, in any of the embodiments, the plurality of tails may include a plurality of proximal tails and a plurality of distal tails. The plurality of proximal tails may be disposed proximate to the proximal end of the balloon and the plurality of distal tails may be disposed proximate to the distal end of the balloon. The reinforcement may be disposed over the plurality of proximal tails or over the plurality of distal tails. A first and second reinforcement may be provided such that the first reinforcement may be disposed over the plurality of distal tails and the second reinforcement may be disposed over the plurality of proximal tails. Where two reinforcements are employed, they may be symmetric with each other.
In any of the foregoing embodiments, the membrane may further include irrigation apertures disposed therethrough. Additionally, the membrane may further include a plurality of ablation electrodes. These electrodes may be disposed on the substrates. Furthermore, a filament may be disposed between the membrane and at least one of the plurality of tails. The filament may comprise a liquid-crystal polymer, such as Vectran.
The balloon may be incorporated or connected to a distal end of a catheter. The catheter may include a shaft having a first shaft portion and second shaft portion at least partially disposed within the first shaft portion. A ring or rings may be disposed about at least a portion of the first reinforcement, second reinforcement (if included), or both to aid in connecting the balloon to the catheter. Additionally, the catheter shaft may have telescoping functionality such that the second shaft portion may be disposed within the first shaft portion.
The catheter may be used according to various methods and variations. For example, after receiving the catheter, the balloon may be deployed from the catheter's lumen. Then the balloon may be expanded, collapsed, and withdrawn back into the lumen. These steps of deploying, expanding, collapsing, and withdrawing may be repeated between five to twenty times. Further, the ablation electrodes may be activated. Typically, the ablation electrodes may be activated after each expanding step and before each collapsing step.
While the specification concludes with claims, which particularly point out and distinctly claim the subject matter described herein, it is believed the subject matter will be better understood from the following description of certain examples taken in conjunction with the accompanying drawings, in which like reference numerals identify the same elements and in which:
The following detailed description should be read with reference to the drawings, in which like elements in different drawings are identically numbered. The drawings, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of the invention. The detailed description illustrates by way of example, not by way of limitation, the principles of the invention. This description will clearly enable one skilled in the art to make and use the invention, and describes several embodiments, adaptations, variations, alternatives and uses of the invention, including what is presently believed to be the best mode of carrying out the invention.
As used herein, the terms “about” or “approximately” for any numerical values or ranges indicate a suitable dimensional tolerance that allows the part or collection of components to function for its intended purpose as described herein. More specifically, “about” or “approximately” may refer to the range of values ±10% of the recited value, e.g. “about 90%” may refer to the range of values from 81% to 99%. In addition, as used herein, the terms “patient,” “host,” “user,” and “subject” refer to any human or animal subject and are not intended to limit the systems or methods to human use, although use of the subject invention in a human patient represents a preferred embodiment.
Ablation of cardiac tissue to correct a malfunctioning heart is a well-known procedure. Typically, to successfully ablate, cardiac electropotentials need to be measured at various locations of the myocardium. In addition, temperature measurements during ablation provide data enabling the efficacy of the ablation to be measured. Typically, for an ablation procedure, the electropotentials and the temperatures are measured before, during, and after the actual ablation.
An ablation catheter may include a lumen, and a balloon may be deployed through the catheter lumen. A multi-layer flexible metal structure is attached to an exterior wall or membrane of the balloon. The structure comprises a plurality of electrode groups arranged circumferentially about the longitudinal axis, where each electrode group comprises multiple ablation electrodes, typically arranged longitudinally.
Each electrode group may also include at least one micro-electrode that is insulated physically and electrically from the ablation electrodes in its group.
Each electrode group may also include at least a thermocouple.
In some embodiments, each electrode group has a micro-electrode and a thermocouple formed at a common location.
Using a single catheter, with the three functionalities of ability to perform ablation, electropotential measurement, and temperature measurement, simplifies cardiac ablation procedures.
To perform the ablation, medical professional 14 inserts a probe 20 into a sheath 21 that has been pre-positioned in a lumen of the patient. Sheath 21 is positioned so that a distal end 22 of probe 20 enters the heart of the patient. A diagnostic/therapeutic catheter 24 (e.g., a balloon catheter), which is described in more detail below with reference to
As shown in
The software for the processor 46 may be downloaded to the processor in electronic form, over a network, for example. Alternatively, or additionally, the software may be provided on non-transitory tangible media, such as optical, magnetic, or electronic storage media. The tracking of the distal end 22 is may be displayed on a three-dimensional representation 60 of the heart of the patient 18 on a screen 62. However, it may be displayed two-dimensionally, e.g., by fluoroscopy or MRI.
To operate apparatus 12, the processor 46 communicates with a memory 50, which has many modules used by the processor to operate the apparatus. Thus, the memory 50 comprises a temperature module 52, an ablation module 54, and an electrocardiograph (ECG) module 56, the functions of which are described below. The memory 50 typically comprises other modules, such as a force module for measuring the force on the distal end 22, a tracking module for operating the tracking method used by the processor 46, and an irrigation module allowing the processor to control irrigation provided for the distal end 22. For simplicity, such other modules are not illustrated in
The balloon 80 of the diagnostic/therapeutic catheter 24 has an exterior wall or membrane 26 of a bio-compatible material, for example, formed from a plastic such as polyethylene terephthalate (PET), polyurethane, Pellethane® or PEBAX®. The shaft 70 and the distal shaft end 88 define a longitudinal axis 78 of the balloon 80. The balloon 80 is deployed, in a collapsed configuration, via the lumen 23 of the probe 20, and may be expanded to an expanded configuration after exiting from the distal end 22 by telescoping the first shaft portion relative to the second shaft portion. The membrane 26 of the balloon 80 is formed with irrigation pores or apertures 27 (shown in
The membrane 26 supports and carries a combined electrode and temperature sensing member which is constructed as a multi-layer flexible circuit electrode assembly 84. The “flex circuit electrode assembly” 84 may have many different geometric configurations. In the illustrated embodiment, the flex circuit electrode assembly 84 has a plurality of radiating substrates or strips 30. The substrates 30 are evenly distributed about membrane 26 of balloon 80. Each substrate has wider proximal portion that gradually tapers to a narrower distal portion.
Each substrate 30 has a proximal tail 31P proximal to the wider proximal portion and a distal tail 31D distal of the narrower distal portion. The proximal tail 31P may be tucked under and fastened to the catheter 24 by a proximal ring 28P mounted on the proximal shaft portion 82 of the shaft 70. The distal tail 31D may be tucked under and fastened to catheter 24 at distal shaft end 88 by distal ring or cap 28D.
For simplicity, the flex circuit electrode assembly 84 is described with respect to one of its substrates 30 as shown in
The substrate 34 is formed with one or more irrigation pores or apertures 35 that are in alignment with the irrigation apertures 27 of the balloon member 26 so that fluid passing through the irrigation apertures 27 and 35 can pass to the ablation site on the ostium.
The substrate 34 has a first or outer surface 36 facing away from the balloon membrane 26, and a second or inner surface 37 facing the balloon membrane 26. On its outer surface 36, the substrate 34 supports and carries the contact electrodes 33 adapted for tissue contact with the ostium. On its inner surface 37, the substrate 34 supports and carries a wiring electrode 38. The contact electrode 33 delivers RF energy to the ostium during ablation or is connected to a thermocouple junction for temperature sensing of the ostium. In the illustrated embodiment, the contact electrode 33 has a longitudinally elongated portion 40 and a plurality of thin transversal linear portions or fingers 41 extending generally perpendicularly from each lateral side of the elongated portion 40 between enlarged proximal and distal ends 42P and 42D, generally evenly spaced therebetween. The elongated portion 40 has a greater width and each of the fingers has a generally uniform lesser width. Accordingly, the configuration or trace of the contact electrode 33 may resemble a “fishbone” but it should be noted that the invention is not limited to such configuration. In contrast to an area or “patch” ablation electrode, the fingers 41 of the contact electrode 33 advantageously increase the circumferential or equatorial contact surface of the contact electrode 33 with the ostium while void regions 43 between adjacent fingers 41 advantageously allow the balloon 80 to collapse inwardly or expand radially as needed at locations along its equator. In the illustrated embodiment, the fingers 41 have different lengths, some being longer, others being shorter. For example, the plurality of fingers includes a distal finger, a proximal finger and fingers therebetween, where each of the fingers in between has a shorter adjacent finger. For example, each finger has a length different from its distal or proximal immediately adjacent neighboring finger(s) such that the length of each finger generally follows the tapered configuration of each substrate 30. In the illustrated embodiment, there are 22 fingers extending across (past each lateral side of) the elongated portion 40, with the longest finger being the third finger from the enlarged proximal end 42P. In some embodiments, the contact electrode 33 includes gold 58B with a seed layer between the gold 58B and the membrane 26. The seed layer may include titanium, tungsten, palladium, silver, or combinations thereof.
Formed within the contact electrode 33 are one or more exclusion zones 47, each surrounding an irrigation aperture 35 formed in the substrate 34. The exclusion zones 47 are voids purposefully formed in the contact electrode 33, as explained in detail further below, so as to avoid damage to the contact electrode 33 during construction of the electrode assembly 84 in accommodating the irrigation apertures 35 at their locations and in their function.
Also formed in the contact electrode 33 are one or more conductive blind vias 48 which are conductive or metallic formations that extend through through-holes in the substrate 34 and are configured as electrical conduits connecting the contact electrode 33 on the outer surface 36 and the wiring electrode 38 on the inner surface 37. It is understood that “conductive” is used herein interchangeably with “metallic” in all relevant instances.
In the illustrated embodiment, the contact electrode 33 measures longitudinally between about 0.1 inch and 1.0 inch, and preferably between about 0.5 inch and 0.7 inch, and more preferably about 0.57 inch, and has four exclusion zones 47 and nine blind vias 48.
On the inner surface 37 of the substrate 34, the wiring electrode 38 is generally configured as an elongated body generally similar in shape and size to the elongated portion 40 of the contact electrode 33. The wiring electrode 38 loosely resembles a “spine” and also functions as a spine in terms of providing a predetermined degree of longitudinal rigidity to each substrate 30 of the electrode assembly 84. The wiring electrode 38 is positioned such that each of the blind vias 48 is in conductive contact with both the contact electrode 33 and the wiring electrode 38. In the illustrated embodiment, the two electrodes 33 and 38 are in longitudinal alignment with other, with all nine blind vias 48 in conductive contact with both electrodes 33 and 38. In some embodiments, the wiring electrode 38 has an inner portion of copper 57 and an outer portion of gold 58.
The wiring electrode 38 is also formed with its exclusion zones 59 around the irrigation apertures 35 in the substrate 34. The wiring electrode 38 is further formed with solder pad portions 61, at least one active 61A, and there may be one or more inactive solder pad portions 61B. The solder pad portions 61A and 61B are extensions from a lateral side of the elongated body of the wiring electrode 38. In the illustrated embodiment, an active solder pad portion 61A is formed at about a mid-location along the elongated body, and a respective inactive solder pad portion 61B is provided at each of the enlarged distal end 42D and the enlarged proximal end 42P.
Attached, e.g., by a solder weld 63, to the active solder pad portion 61A are the wire pair, e.g., a constantan wire 51 and a copper wire 53. The copper wire 53 provides a lead wire to the wiring electrode 33, and the copper wire 53 and the constantan wire 51 provide a thermocouple whose junction is at solder weld 63. The wire pair 51/53 are passed through a through-hole 29 formed in the membrane 26. It is understood that, in other embodiments in the absence of the through-hole 29, the wire pair 51/53 may run between the membrane 26 and the substrate 34 and further proximally between the membrane 26 and the proximal tail 31P until the wire pair 51/53 enters the tubular shaft 70 via another through-hole (not shown) formed in the tubular shaft sidewall closer to the proximal ring 28P.
The flex circuit electrode assembly 84, including the substrates 30 and the tails 31P and 31D, is affixed to the balloon membrane 26 such that the outer surface 36 of the substrate 34 is exposed and the inner surface 37 of the substrate 34 is affixed to the balloon membrane 26, with the wiring electrode 38 and wire pair 51/53 sandwiched between the substrate 34 and the balloon membrane 26. The irrigation apertures 35 in the substrate 34 are aligned with the irrigation apertures 27 in the balloon membrane 26. The exclusion zones 59 in the wiring electrode 38 and the exclusion zones 47 in the contact electrode 33 are concentrically aligned with each other, as well as with the irrigation apertures 27 and 35 in balloon 26 and substrate 34, respectively.
Further details on constructing a diagnostic/therapeutic catheter in accordance with the foregoing disclosure may be found in U.S. patent application Ser. No. 15/360,966, published as U.S. Patent Application Publication No. 2017/0312022, which is incorporated by reference herein in its entirety.
Through ongoing research and product development efforts concerning the subject matter described above, Applicant has determined that balloon 80 must be able to withstand multiple cycles of being deployed from lumen 23 of probe 20 in the collapsed configuration, expanded to the expanded configuration, returned to the collapsed configuration and withdrawn into lumen 23 of probe 20. The number of cycles may be from about five to about twenty. That is, the connection between substrate 30 and membrane 26 of balloon 80 and overall integrity of the assembled balloon must withstand at least five to twenty fatigue cycles and any additional frictional stresses experienced during five to twenty deployments from and five to twenty withdrawals into lumen 23. Applicant believes that there is a very small likelihood of potential delamination of proximal tails 31P and distal tails 31D from membrane 26, which could arise from repeated fatiguing and has implemented a solution that would prevent, or at least significantly further lower the likelihood of, any such delamination. Applicant further determined that any such solution would need to accommodate for various design constraints, such as: 1) minimizing concomitant safety concerns caused by any solution; 2) minimizing any increase to diameter of the portions of balloon 80 upon which distal tails 31D and proximal tails 31P are adhered such that balloon 80 in the collapsed configuration may be readily deployed from and withdrawn into lumen 23 with little or no increase in friction therebetween (or especially, in the extreme, avoiding a need to increase the diameter of lumen 23); 3) minimizing any increase to the stiffness of balloon 80, which could interfere with establishing contact between electrode 30 and tissue during a procedure; 4) not impeding electrical contact between electrodes 33 and tissue during a procedure; and 5) minimizing an increase to the number of assembly steps.
Disclosed herein is a reinforcement or reinforcement component 100 that assists in preventing the delamination problem without violating the design constraints. Reinforcement component 100 may have a shape like and thus conform to a proximal or distal portion of membrane 26. For example, reinforcement component 100 may include a portion of an unassembled catheter balloon 80, i.e., a balloon 80 that has not been assembled to any other components of catheter 24, such as substrates 30. That is, a balloon 80 may have a portion separated therefrom by cutting membrane 26 along one of the lines 86 as seen in
Thus, reinforcement component 100 may be provided as having a horn-like (e.g., bell-mouth) shape as seen in
In further embodiments, the likelihood of delamination may be further reduced by supporting one or more of the tails (e.g., all of the tails) with a length of filament between membrane 26 and a respective tail 31P or 31D. Ideally the filament material is one that bonds readily to both the substrate material and the membrane material, such that the filament may increase the robustness of the connection between the tails and the membrane. Suitable materials include liquid crystal polymers, such as VECTRAN™ or preferably Ultra-High Molecular Weight Polymer such as Honeywell SPECTRA™.
By virtue of the embodiments illustrated and described herein, applicant has devised a method of using a diagnostic/therapeutic catheter having a balloon upon which is disposed various components suitable for ablating tissues, the method including repeated steps that may stress connections between the balloon and the catheter. Specifically, a catheter, such as the one heretofore described (e.g., catheter 24) may be received by a user. The user may deploy the balloon from the catheter, expand the balloon, collapse the balloon, and withdraw the balloon into the catheter. These steps may be repeated between five to fifteen, e.g., ten times. Moreover, the user may use electrodes disposed on the balloon to ablate tissue, typically between the steps of expanding and collapsing the balloon.
Any of the examples or embodiments described herein may include various other features in addition to or in lieu of those described above. The teachings, expressions, embodiments, examples, etc. described herein should not be viewed in isolation relative to each other. Various suitable ways in which the teachings herein may be combined should be clear to those skilled in the art in view of the teachings herein.
Having shown and described exemplary embodiments of the subject matter contained herein, further adaptations of the methods and systems described herein may be accomplished by appropriate modifications without departing from the scope of the claims. In addition, where methods and steps described above indicate certain events occurring in certain order, it is intended that certain steps do not have to be performed in the order described but, in any order as long as the steps allow the embodiments to function for their intended purposes. Therefore, to the extent there are variations of the invention, which are within the spirit of the disclosure or equivalent to the inventions found in the claims, it is the intent that this patent will cover those variations as well. Some such modifications should be apparent to those skilled in the art. For instance, the examples, embodiments, geometrics, materials, dimensions, ratios, steps, and the like discussed above are illustrative. Accordingly, the claims should not be limited to the specific details of structure and operation set forth in the written description and drawings.
The present application claims priority under 35 U.S.C. § 119 to U.S. Provisional Patent Application No. 62/692,439, filed Jun. 29, 2018. The entire contents of this application is incorporated by reference herein in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 62692439 | Jun 2018 | US |
