Patent Application
20100256629
The present invention relates generally to medical devices used for visualizing and/or assessing regions of tissue within a body. More particularly, the present invention relates to methods and apparatus for visualizing and/or assessing regions of tissue within a body, such as the chambers of a heart, to facilitate diagnoses and/or treatments for the tissue.
Conventional devices for accessing and visualizing interior regions of a body lumen are known. For example, ultrasound devices have been used to produce images from within a′body in vivo. Ultrasound has been used both with and without contrast agents, which typically enhance ultrasound-derived images.
Other conventional methods have utilized catheters or probes having position sensors deployed within the body lumen, such as the interior of a cardiac chamber. These types of positional sensors are typically used to determine the movement of a cardiac tissue surface or the electrical activity within the cardiac tissue. When a sufficient number of points have been sampled by the sensors, a “map” of the cardiac tissue may be generated.
Another conventional device utilizes an inflatable balloon which is typically introduced intravascularly in a deflated state and then inflated against the tissue region to be examined. Imaging is typically accomplished by an optical fiber or other apparatus such as electronic chips for viewing the tissue through the membrane(s) of the inflated balloon. Moreover, the balloon must generally be inflated for imaging. Other conventional balloons utilize a cavity or depression formed at a distal end of the inflated balloon. This cavity or depression is pressed against the tissue to be examined and is flushed with a clear fluid to provide a clear pathway through the blood.
Moreover, many of the conventional imaging systems lack the capability to provide therapeutic treatments or are difficult to manipulate in providing effective therapies. For instance, the treatment in a patient's heart for atrial fibrillation is generally made difficult by a number of factors, such as visualization of the target tissue, access to the target tissue, and instrument articulation and management, amongst others.
Thus, such imaging balloons have many inherent disadvantages. For instance, such balloons typically lack mechanisms for treating a region of tissue visualized through the balloon. Treatment is often limited to ablation energy delivered by electrodes positioned along the balloon exterior or through laser energy transmitted directly through the balloon membrane. Contacting electrodes on the balloon surface against tissue, particularly tissue which may be moving such as a beating heart, may result in unsteady or uneven energy delivery while delivering laser energy often requires the balloon to remain in steady contact against the tissue region to be treated.
These types of imaging modalities are generally unable to provide desirable images useful for sufficient diagnosis and therapy of the endoluminal structure, due in part to factors such as dynamic forces generated by the natural movement of the heart. Accordingly, devices and methods which may effectively image underlying tissue while also effectively delivering energy to the tissue is desired.
Generally, the ablation catheter assembly may comprise a catheter defining at least one lumen therethrough and an inflatable assembly positioned along the catheter. A guidewire may be advanced through catheter for guiding and positioning the assembly intravascularly and into position against the ostium of a vessel such as a pulmonary vein. The inflatable assembly may be inflated prior to placement against the ostium or after positioning the catheter in proximity to the ostium, if desired. The inflatable assembly may comprise an outer membrane having one or more openings, pores, or ports over a contact surface defined along a distal portion of the membrane. An inner membrane may be attached to the catheter while contained entirely within the outer membrane such that an annular space is formed between the outer and inner membranes. An outer membrane fluid port may also be defined along the catheter within the annular space to introduce a clear conductive fluid therethrough. Additionally, an imaging element such as an optical fiber or electronic imager (e.g., CCD, CMOS, etc.) may be positioned within the inner balloon or along the catheter such that the contacted and/or visualized tissue may be viewed through the clear fluid as well as through both inner and outer membranes. Either or both the outer and inner membranes may be fabricated from a clear and/or elastic material such as (but not limited to), e.g., polyurethane, silicone, etc.
As the fluid (e.g., a biocompatible liquid or inert gas such as saline or deuterium) is introduced within the inner membrane, one or more electrodes which are positioned along the inner membrane may be pushed out into proximity with the openings or pores of the outer membrane. A conductive fluid such as saline may be introduced into the annular space such that the conductive fluid may flow distally into the space and out the openings or pores. The imager within the balloon can be utilized to determine the appropriate level of inflation given that the tissue becomes clearly visible once the balloon is inflated such that it is in firm contact with the tissue. Upon the confirmation of adequate contact and a clear field of view, radiofrequency (RF) energy can be delivered via the electrodes and through the saline within the annular space to deliver ablative energy to the contacted underlying tissue.
Since the underlying tissue is ablated according to the flow of the saline, the raised openings or pores may provide specified pathways for the outflow of saline thereby controlling the development of lesions on the tissue surface of the ostium. Additionally, the space formed between the raised openings or pores may create channels for the blood flowing from the pulmonary vein to continue flowing throughout the procedure without completely occluding the blood flow.
Other variations of the balloon catheter may utilize one or more longitudinal or circumferential ridges which define one or more openings or pores therealong. The ridges may provide for improved re-direction of irrigation fluid through the openings or pores and into contact against the ostium as well as improved blood flow past the balloon between the ridges. Alternatively, one or more patches or groupings of openings or pores may be clustered around the distal portion of the balloon for contact against the ostium. Such a design may allow for expansion of the balloon in a manner to fit the anatomy securely.
In yet another variation, an electrode band may be defined circumferentially over a distal portion of the balloon where one or more openings or pores are circumferentially aligned along the band through the outer membrane. A rotatable fluid lumen may be optionally rotated within the balloon interior to direct a conduit opening adjacent to a selected opening along the electrode band to direct the irrigating conductive fluid to flow selectively from an individual opening.
Other variations may utilize a flexible frame which extends distally from the catheter along the interior of the balloon assembly. The frame may be comprised of a shape memory alloy which may be self expanding to allow for the frame and assembly to press fit securely against the ostium. Another variation may have one or more frame members extending radially with one or more corresponding wires attached at the free ends of each member. When tensioned, each of the members may be curved proximally, much like a crossbow, such that the assembly obtains a relatively lower profile for positioning within or against the ostium. The wire may be pushed or released such that the members may relax and extend radially relative to catheter such that the assembly obtains a larger profile and expands to conform to the shape of the ostium. Alternatively, pincer-like members may also be used.
Yet other variations may utilize one or more pivoting supports positioned within the assembly such that as the balloon is inflated into contact against the ostium each of the individual supports may pivot to conform to the underlying anatomy of the ostium.
In another alternative for securing the balloon against the ostium, the balloon itself may be modified in addition to or separate from the use of a frame. One example may include a balloon having one or more electrodes formed along a circumferential portion of the balloon which is recessed along a distal portion of the balloon. The openings along the recessed portion may each have a ring-shaped electrodes circumferentially positioned about the opening to provide the ablation energy.
Yet another variation of a balloon catheter may utilize an inner balloon which may be inflated at a pressure that is relatively higher than a pressure used to inflate the outer balloon. The outer balloon may be compliant enough to conform to the surface of the ostium while the relatively higher pressure inner balloon may be relatively stiffer to ensure that the balloon assembly is still readily positionable against the ostium without fear of buckling or collapsing the balloon assembly.
Yet another example includes an additional occluding balloon positioned along the catheter distal to the assembly. The occluding balloon may be placed within the vessel and inflated via a fluid or gas introduced through an opening along the catheter and into the balloon to serve as an anchor for the assembly. The occlusion balloon may also temporarily occlude the blood flow through the vessel. With blood flow temporarily occluded, the assembly may be inflated to position the openings against the ostium for ablation treatment. Optionally, the distal balloon and inflation assembly may be adjustable relative to one another via a telescoping section. Alternatively, an additional balloon may be positioned between the occlusion balloon and inflation assembly.
In yet another variation, the balloon may define one or more channels therethrough for shunting blood flow through the balloon thus eliminating the need to occlude the balloon and facilitating stabilization of the balloon relative to the ostium. Alternatively, the balloon may comprise a split chamber in which the balloon is inflated such that it both occludes the pulmonary vein and also engages and presses the one or more openings and electrodes directly onto the ostium.
In utilizing the imager for visualizing the underlying tissue, an optical fiber assembly or electronic imager (such as a CCD or CMOS imager) may be utilized. To facilitate the visualization of a relatively larger region of tissue, the imager may incorporate a convex lens positioned distal to the imager to create a fisheye lens effect that is able to visualize an increased viewing angle whilst affixed at a single spot inside the balloon.
Various exemplary embodiments of the invention are described below. Reference is made to these examples in a non-limiting sense. They are provided to illustrate more broadly applicable aspects of the present invention. Various changes may be made to the invention described and equivalents may be substituted without departing from the true spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation, material, composition of matter, process, process act(s) or step(s) to the objective(s), spirit or scope of the present invention. All such modifications are intended to be within the scope of the claims made herein.
The tissue-imaging and manipulation apparatus of the invention is able to provide real-time images in vivo of tissue regions within a body lumen such as a heart, which are filled with blood flowing dynamically through the region. The apparatus is also able to provide intravascular tools and instruments for performing various procedures upon the imaged tissue regions. Such an apparatus may be utilized for many procedures, e.g., visualizing and/or treating the ostium of vessels such as the ostia of the pulmonary veins for treating conditions such as atrial fibrillation. Disclosure and information regarding tissue visualization catheters generally which can be applied to the invention are shown and described in further detail in commonly owned U.S. patent application Ser. No. 11/259,498 filed Oct. 25, 2005 (U.S. Pat. Pub. 2006/0184048 A1), which is incorporated herein by reference in its entirety.
Aside from visualization and/or treatment of the ostium of a vessel, other procedures may be accomplished. Additional examples of such procedures are described in further detail in U.S. patent application Ser. No. 11/763,399 filed Jun. 14, 2007 (U.S. Pat. Pub. 2007/0293724 A1), which is incorporated herein by reference in its entirety. Additionally, details of tissue visualization and manipulation catheter which may be utilized with apparatus and methods described herein are described in U.S. patent application Ser. No. 11/259,498 filed Oct. 25, 2005 (U.S. Pat. Pub. 2006/0184048 A1), which is incorporated herein by reference in its entirety. Additional details and examples are further described in U.S. patent application Ser. No. 11/775,837 filed Jul. 10, 2007 (U.S. Pat. Pub. 2008/0009747 A1); Ser. No. 11/828,267 filed Jul. 25, 2007 (U.S. Pat. Pub. No. 2008/0033290 A1); Ser. No. 12/118,439 filed May 9, 2008 (U.S. Pat. Pub. 2009/0030412 A1); Ser. No. 12/201,811 filed Aug. 29, 2008 (U.S. Pat. Pub. 2009/0062790 A1); Ser. No. 12/209,057 filed Sep. 11, 2008 (U.S. Pat. Pub. 20090076498 A1); and Ser. No. 12/323,281 filed Nov. 25, 2008 (U.S. Pat. Pub. No. 2009/0143640 A 1), each of which may be utilized herewith. Each of these applications is incorporated herein by reference in its entirety.
In particular, such assemblies, apparatus, and methods may be utilized for treatment of various conditions, e.g., arrhythmias, through ablation under direct visualization. Details of examples for the treatment of arrhythmias under direct visualization which may be utilized with apparatus and methods described herein are described, for example, in U.S. patent application Ser. No. 11/775,819 filed Jul. 10, 2007 (U.S. Pat. Pub. No. 2008/0015569 A1), which is incorporated herein by reference in its entirety. Variations of the tissue imaging and manipulation apparatus may be configured to facilitate the application of bipolar energy delivery, such as radio-frequency (RF) ablation, to an underlying target tissue for treatment in a controlled manner while directly visualizing the tissue during the bipolar ablation process as well as confirming (visually and otherwise), appropriate treatment thereafter.
In utilizing an inflatable balloon for treatment of an ostium of a vessel, the inflatable balloon may generally comprise a visual electrode assembly which utilizes an expandable membrane which is enclosed except for one or more side purging ports through which the purging fluid may escape. One or more electrodes may be positioned along a support member or directly upon the balloon to deliver ablation energy conducted through the purging fluid and into or against the underlying tissue region to be treated in close proximity to the purging ports. Because the surface of the balloon membrane may be tapered, the assembly may be particularly suited for positioning against the ostium of a pulmonary vein so that the ablation energy discharged from the electrode may be directed through the purging fluid escaping through the one or more purging ports and into the tissue surrounding the ostium. A distal balloon anchor may be positioned along a distal tip or portion of the support catheter for advancement into the pulmonary vein to provide temporary anchoring for the assembly.
Generally, as shown in the side and cross-sectional side views of
The inflatable assembly 14 may comprise an outer membrane 24 attached at its proximal end 30 and distal end 32 to the catheter 12 and the outer member 24 may also define one or more openings, pores, or ports 22 over a contact surface 20 defined along a distal portion of the membrane 24. These openings or pores 22 may each comprise a raised portion over a circumference of the membrane 24. An inner membrane 26 may be attached to the catheter 12 along its proximal 34 and distal end 36 while contained entirely within outer membrane 24 such that an annular space 28 is formed between the outer 24 and inner membranes 26. The catheter 12 may define an inner membrane fluid port 38 through which a clear fluid may be introduced into the interior of the inner membrane 26 to inflate or expand the inner balloon. An outer membrane fluid port 40 may also be defined along the catheter 12 within the annular space 28 to introduce a clear conductive fluid therethrough. Additionally, an imaging element 42 such as an optical fiber or electronic imager (e.g., CCD, CMOS, etc.) may be positioned within the inner balloon or along the catheter 12 such that the contacted and/or visualized tissue may be viewed through the clear fluid as well as through both inner 26 and outer 24 membranes. Either or both the outer 24 and inner 26 membranes may be fabricated from a clear and/or elastic material such as (but not limited to), e.g., polyurethane, silicone, etc.
As the fluid (e.g., a biocompatible liquid or inert gas such as saline or deuterium) is introduced within inner membrane 26 through opening 38, one or more electrodes 44 which are positioned along the inner membrane 26 may be pushed out into proximity with the openings or pores 22 of the outer membrane 24. A conductive fluid such as saline may be introduced through opening 40 into the annular space 28 such that the conductive fluid may flow distally into the space and out the openings or pores 22. The imager 42 within the balloon can be utilized to determine the appropriate level of inflation given that the tissue becomes clearly visible once the balloon is inflated such that it is in firm contact with the tissue. Upon the confirmation of adequate contact and a clear field of view, radiofrequency (RF) energy can be delivered via the electrodes 44 and through the saline within the annular space 28 to deliver ablative energy to the contacted underlying tissue. Further examples for delivering ablation energy conducted through a fluid are described in further detail in Ser. No. 12/201,811 filed Aug. 29, 2008 (U.S. Pat. Pub. 2009/0062790 A1), which has been incorporated herein by reference.
Since the underlying tissue is ablated according to the flow of the saline, the raised openings or pores 22 may provide specified pathways for the outflow of saline thereby controlling the development of lesions on the tissue surface of the ostium OS. Additionally, the space formed between the raised openings or pores 22 may create channels for the blood flowing from the pulmonary vein to continue flowing throughout the procedure without completely occluding the blood flow.
In treating conditions such as atrial fibrillation, studies have shown that it is generally advantageous to create a conduction block around the ostium OS of the pulmonary vein in the left atrium of the heart. A conduction block may be created by a variety of methods that include but are not limited to direct application of not only RF energy, but also laser energy, ultrasound energy, cryo-ablative energy, etc.
With the introduction of an irrigating fluid, hematocrit and the chances of clotting may be potentially reduced during such a procedure. Additionally, because the inflation fluid within inner membrane 26 and the irrigating fluid within the annular space 28 are clear, visualization of the tissue area may be maintained during the procedure and further allows for the unobstructed and uniform delivery of ablative energy. Moreover, the irrigating fluid may also cool the surface of the ostium OS potentially preventing overheating or burning of the tissue or coagulation.
When performing visualization and treatment with a balloon inside a heart, the tissue surface is constantly moving in accordance with the heart beat and there is an outflow of blood from the pulmonary vein. Moreover, the ostium of one or more of the pulmonary veins may be irregularly shaped in an inconsistent manner between patients. These factors, amongst others, typically contribute to the dislodgement of balloons from the ostium. Thus, mechanisms may be utilized for maintaining contact between the balloon and ostium surface.
In another alternative for securing the balloon against the ostium, the balloon itself may be modified in addition to or separate from the use of a frame. One example is shown in the side view of
Yet another example is shown in the cross-sectional view of
In utilizing the imager for visualizing the underlying tissue, an optical fiber assembly or electronic imager (such as a CCD or CMOS imager) may be utilized. To facilitate the visualization of a relatively larger region of tissue, an imager 280 such as the variation shown in the side view of
The applications of the disclosed invention discussed above are not limited to certain treatments or regions of the body, but may include any number of other treatments and areas of the body. Modification of the above-described methods and devices for carrying out the invention, and variations of aspects of the invention that are obvious to those of skill in the arts are intended to be within the scope of this disclosure. Moreover, various combinations of aspects between examples are also contemplated and are considered to be within the scope of this disclosure as well.
This application claims the benefit of priority to U.S. Prov. Pat. App. 61/167,016 filed Apr. 6, 2009, which is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61167016 | Apr 2009 | US |
