This invention relates to balloon catheters and specifically to balloon catheters used to treat atrial fibrillation by creating regions of electrically non-conducting tissue in the region of the left atrium where generally the pulmonary veins join the left atrium. Prior art describes balloon catheters which can ablate tissue in the regions of the pulmonary veins and specifically balloon catheters which ablate tissue using laser energy of 980 nm or similar and also employ a endoscopes positioned inside the balloons of such catheters to view how the balloons contact the atrial tissue. Such endoscopic visualization allows for aiming of the laser energy into tissue contacting the balloon as opposed aiming the laser into areas of the balloon not in contact with atrial tissue since such latter energy delivery would be ineffective at creating lesions which block electrical conduction of the atrial tissue.
The overall aims of the invention are to provide a balloon catheter system that allows for a much greater area of contact between the balloon and the atrial tissue than is achievable by prior art. Greater area of tissue contact is highly desirable since it allows for more flexibility in choosing locations to deliver laser energy. Such flexibility is desirable to avoid areas adjacent to structures which might be damaged by energy delivery such as the esophagus or the phrenic nerve. A greater area of contact also means that less time must be spent manipulating the balloon in order to achieve a balloon position where contact is adequate to allow for the delivery of the desired pattern of lesions in the region of the pulmonary vein ostium. The invention achieves the aim of increasing balloon to tissue contact area by the following means:
How these means increase tissue contact with the balloon and how these means are implemented in actual practice are described in more detail below.
Physics of Balloon Contact with Tissue
A=F/PB Sin Θ (1)
From the above equation is can be seen that operating a low balloon pressure is desirable to increase the contact area of the balloon with the tissue. There are practical limits to how much force F can be applied to the catheter shaft. That force must not exceed a force that would damage atrial tissue. There are also practical limits to the taper angle of the balloon Θ. Balloons must interface with pulmonary veins of varying sizes so it is desired that the balloons have small diameter distal ends to be able to enter the smaller veins but the balloon must also have large maximum diameter in order to prevent the balloons form entering too deeply into large veins. If too small a value of theta is selected then the difference between the distal end of the balloon and the maximum diameter will be too small to allow the balloon to interface properly with a greatest range of vein sizes.
Details of the Invention Related to the Balloon
Prior art balloons have been made of elastomeric materials such as Urethane with a durometer of 90 shore A. In use these balloons are inflated to pressures of 2 to 5 PSI. The range of pressure is used in order to adjust the maximum diameter of the balloon in order to create balloon sizes compatible with an even greater range pulmonary vein sizes than is provided for by the tapered shape of the balloon. In use prior art balloons are inflated over the range of pressure stated in order to achieve maximum diameters ranging from 25 mm to 35 mm. The balloons of the current invention employ Urethane, Silicone Rubber or Polyisoprene materials in durometers ranging from 80 Shore A to 50 Shore A. In use, these balloons 100 will be inflated to pressures of 0.2 PSI to 1 PSI. These much lower pressures enable greater contact area to be achieved as described above. The lower material durometers enable the balloons to be inflated to the same range of diameters of 25 mm to 35 mm while still maintaining the lower balloon pressure of 0.2 PSI to 1 PSI desired to achieve greater tissue contact with the balloon.
Details of the Invention Related to the Fluid Management System
The balloons 100 of the balloon catheters 10 described here are inflated with a transparent incompressible fluid. Deuterium Oxide is the fluid of choice since it is very transparent to 980 nm laser energy generally employed. However water, saline and even compressible fluids could be employed instead. The inflation media serves to inflate the balloon and is also continuously circulated through the balloon and catheter in order prevent the balloon and other catheter components from becoming too hot during energy delivery.
In this system, the balloon pressure is regulated by changing the speed of the volumetric pump 22. For a given pump speed pressure, the balloon 26 will increase until equilibrium is reached where the pressure in the balloon 26 is sufficient to create a return flow rate back to the reservoir 20 through the second (return) lumen 25 in the multi-lumen catheter and the tubing back to the reservoir 20 that matches the flow rate of the volumetric pump 22. In general, the flow rates and lumen sizes are such that laminar flow exists in the flow passages when Deuterium Oxide or water is used as the inflation media 21. The laminar flow regime creates a condition where the balloon pressure is directly proportional to the flow rate from the volumetric pump 22.
To deflate the balloon 26, the volumetric pump 22 is run in reverse. A check valve 27 is provided to prevent air from entering the balloon 26 during balloon deflation. It should also be noted that separate pathways are used to withdraw inflation media 21 from the reservoir 20 and to return it to the reservoir 20. In this way any air in the balloon 26 or fluid pathways is expelled from the system during the initial phase when inflation media 21 is introduced into a new dry catheter 10. Any air in the catheter fluid passages returns to the reservoir 20 along with the inflation media 21 and is dissipated as is exits the return tube shown in the figure returning drops of inflation media 21 to the reservoir 20.
The prior art fluid management system is not suitable for use in the present invention where the desired balloon inflation pressures are only 0.2 PSI to 1 PSI. To achieve these low pressures with the prior art system the flow rate must be reduced to a low flow rate that is no longer adequate to cool the balloon and catheter components sufficiently. Additionally, since balloon pressure and axial force on the balloon catheter are related as shown in
In this system 200, a diverter valve 210 is added to the prior art system of
In this configuration of
It is worth noting that when the system 200 is in trapped volume mode, the volumetric pump 22 may create less than atmospheric pressure at the pump intake (this is the left side of the pump as it is shown in
Other valve and pump schemes are possible to achieve the functions described above. For example, the valving functions can easily be achieved by using readily available solenoid operated pinch valve actuators which serve to punch closed standard PVC medical tubing.
With all the described inflation media management systems, the valves and pumps are ideally connected to an automatic control system that allows the desired operations (Purge, Inflate, Increase Balloon Size, Decrease Balloon Size, Deflate and Trapped Volume Mode) to be easily achieved with the press or touch of a button. Ideally such a control system can be fitted with a sterile transparent drape so the fluid control operations can be performed by an operator who scrubbed in and operating the catheter at the same time. However, the systems described are perfectly useful with the valves and pumps being operated individually and manually.
Notably, the figures and examples above are not meant to limit the scope of the present invention to a single embodiment, as other embodiments are possible by way of interchange of some or all of the described or illustrated elements. Moreover, where certain elements of the present invention can be partially or fully implemented using known components, only those portions of such known components that are necessary for an understanding of the present invention are described, and detailed descriptions of other portions of such known components are omitted so as not to obscure the invention. In the present specification, an embodiment showing a singular component should not necessarily be limited to other embodiments including a plurality of the same component, and vice-versa, unless explicitly stated otherwise herein. Moreover, applicants do not intend for any term in the specification or claims to be ascribed an uncommon or special meaning unless explicitly set forth as such. Further, the present invention encompasses present and future known equivalents to the known components referred to herein by way of illustration.
The foregoing description of the specific embodiments will so fully reveal the general nature of the invention that others can, by applying knowledge within the skill of the relevant art(s) (including the contents of the documents cited and incorporated by reference herein), readily modify and/or adapt for various applications such specific embodiments, without undue experimentation, without departing from the general concept of the present invention. Such adaptations and modifications are therefore intended to be within the meaning and range of equivalents of the disclosed embodiments, based on the teaching and guidance presented herein. It is to be understood that the phraseology or terminology herein is for the purpose of description and not of limitation, such that the terminology or phraseology of the present specification is to be interpreted by the skilled artisan in light of the teachings and guidance presented herein, in combination with the knowledge of one skilled in the relevant art(s).
While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example, and not limitation. It would be apparent to one skilled in the relevant art(s) that various changes in form and detail could be made therein without departing from the spirit and scope of the invention. Thus, the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.
The present invention claims priority to U.S. patent application Ser. No. 62/443,270, filed Jan. 6, 2017, which is hereby incorporated by reference in its entirety.
Number | Name | Date | Kind |
---|---|---|---|
3570672 | Bach | Mar 1971 | A |
3794026 | Jacobs | Feb 1974 | A |
4093545 | Cullis | Jun 1978 | A |
5496311 | Abele | Mar 1996 | A |
5746717 | Aigner | May 1998 | A |
5759148 | Sipin | Jun 1998 | A |
5861005 | Kontos | Jan 1999 | A |
6082105 | Miyata | Jul 2000 | A |
6135991 | Muni | Oct 2000 | A |
6241706 | Leschinsky | Jun 2001 | B1 |
20060200191 | Zadno-Azizi | Sep 2006 | A1 |
20060265041 | Sanati | Nov 2006 | A1 |
20060293734 | Scott | Dec 2006 | A1 |
20090012460 | Steck | Jan 2009 | A1 |
20090088735 | Abboud | Apr 2009 | A1 |
20090112151 | Chapman | Apr 2009 | A1 |
20090299356 | Watson | Dec 2009 | A1 |
20100049184 | George | Feb 2010 | A1 |
20100280451 | Teeslink | Nov 2010 | A1 |
20110190751 | Ingle | Aug 2011 | A1 |
20110202084 | Hoem | Aug 2011 | A1 |
20120152842 | Rada | Jun 2012 | A1 |
20130345688 | Babkin | Dec 2013 | A1 |
20140012368 | Sugimoto | Jan 2014 | A1 |
20160015947 | Avevor | Jan 2016 | A1 |
20160029998 | Brister | Feb 2016 | A1 |
20160114281 | Bonano | Apr 2016 | A1 |
20170021076 | Lura | Jan 2017 | A1 |
20180110342 | Moss | Apr 2018 | A1 |
20180296807 | Babko-Malyi | Oct 2018 | A1 |
20180318543 | Coleman | Nov 2018 | A1 |
20200171226 | Wilt | Jun 2020 | A1 |
Number | Date | Country | |
---|---|---|---|
20180193612 A1 | Jul 2018 | US |
Number | Date | Country | |
---|---|---|---|
62443270 | Jan 2017 | US |