This application claims priority to GB application no. 1422607.0, filed Dec. 18, 2014, titled “ ULTRASONICALLY VISIBLE MEDICAL BALLOON ASSEMBLY,” the contents of which application is incorporated herein by reference.
The present invention relates to a balloon catheter assembly, which may in example implementations be configured as a PTA balloon or a device deployment balloon.
Medical balloon assemblies are known in the art, for use for example in angioplasty procedures, for deploying implantable medical devices, and so on.
Medical balloons are typically made of a fine yet strong polymer material, such as polyethylene terephthalate (PETE), polyamide (Nylon) or the like, and are fitted to a balloon catheter, also typically made of a polymer material. These materials have the advantage of being biocompatible, being strong in use and also being flexible, which assists in the trackability of the apparatus, that is its ability to curve and bend through a patient's vasculature as it is fed endoluminally from a remote percutaneous entry point. A problem arises with such balloon catheters, however, in that they are difficult to see during imaging. Although it is possible to use imaging materials, such as contrast media, during the deployment of such balloons, the results are not always optimal. There is also a desire to avoid excessive use of MRI, although the nature of such balloon assemblies currently makes this the best visualization medium.
Similar problems arise with assemblies for deploying implantable medical devices, such as stents, stent grafts, filters and so on; which are conventionally deployed with the aid of MRI scanning.
Visualization of the balloon is particularly important in ensuring that the balloon is precisely positioned at the treatment site before it is deployed.
A number of techniques for enhancing the visibility of balloon catheters, as well as balloon catheter assemblies in general, have been disclosed in US-2014/0039358, US-2014/0024935, U.S. Pat. No. 8,480,647, U.S. Pat. No. 8,043,313, US-2006/0004323 and US-2013/0072792, the contents of which applications are hereby incorporated by reference.
One aspect of the present invention seeks to provide an improved balloon catheter assembly, and in particular an assembly which has a structure and functionality enabling the assembly to be seen by ultrasonic imaging. The balloon assembly can be used for percutaneous transluminal angioplasty (PTA) procedures, for deploying implantable medical devices, or for other purposes.
According to an aspect of the present invention, there is provided a balloon catheter assembly including: a carrier catheter having a distal end and a proximal end, at least first and second lumens passing through the catheter; a balloon assembly including an inner inflatable balloon attached in fluid tight manner at the distal end of the carrier catheter, the inner balloon providing an inner chamber; and an outer inflatable balloon disposed concentrically over the inner balloon, the outer balloon being attached in fluid tight manner at the distal end of the catheter and providing an outer chamber; the first lumen of the catheter including an outlet fluidically coupled to the inner chamber, the second lumen of the catheter including an outlet fluidically coupled to the outer chamber, whereby the inner and outer balloons are independently inflatable; wherein the inner balloon has an inflated diameter no more than 50% of the inflated diameter of the outer balloon.
According to another aspect of the present invention, there is provided a balloon catheter assembly including: a carrier catheter having a distal end and a proximal end, and at least first and second lumens passing through the catheter; a balloon assembly including an inner inflatable balloon attached in fluid tight manner at the distal end of the carrier catheter, the inner balloon providing an inner chamber; and an outer inflatable balloon disposed concentrically over the inner balloon, the outer balloon being attached in fluid tight manner at the distal end of the catheter and providing an outer chamber; wherein the inner balloon has an inflated diameter no more than 50% of the inflated diameter of the outer balloon; the first lumen of the catheter including an outlet fluidically coupled to the inner chamber, the second lumen of the catheter including an outlet fluidically coupled to the outer chamber, whereby the inner and outer balloons are independently inflatable; and a source of echogenic fluid coupled to the first lumen, whereby the inner balloon is inflatable with said echogenic fluid.
The inner balloon can be filled with air, which is highly visible in ultrasonic imaging, thereby avoiding the need to rely on MRI scanning during a medical procedure. The fact that the inner balloon has an inflated diameter substantially less than the inflated diameter of the outer balloon means that the outer balloon does not expand fully, and preferably remains in a wrapped condition during the inflation of the inner balloon, thereby enabling the assembly to be moved within the vessel until it is precisely in the desired location. The outer balloon, which houses the inner balloon, can also act as a protection device to the inner balloon, enabling the inner balloon to be made less strong and therefore typically of thinner and/or more flexible material.
It is preferable that the outer balloon is wrapped over the inner balloon and wherein inflation of the inner balloon does not cause unwrapping of the outer balloon. The outer balloon may be wrapped over the inner balloon so as to have three to six or more folded balloon portions, or wings, wrapped around the carrier catheter.
Preferably, the inner balloon has an inflated diameter of no more than 2 millimetres, more preferably of no more than 1.5 millimetres. This ensures that the inflation of the inner balloon does not cause the outer balloon to unwrap completely, provides sufficient volume of air in a typical balloon assembly to be readily visible in ultrasonic imaging and also that a relatively small amount of air is used in the procedure.
Advantageously, the inner balloon is longitudinally spaced from the outer balloon on the carrier catheter. This ensures that the inner balloon can be wholly contained in the outer balloon and can ensure the assembly is wrappable and compressible to an optimum diameter for delivery.
Advantageously, the inner balloon is shorter than the outer balloon.
In the preferred embodiment, the inner balloon is longitudinally symmetrically disposed within the outer balloon, which enables the clinician to place the assembly precisely in the middle of the treatment site on the basis of the symmetry of the double balloon arrangement.
The assembly preferably includes a source of echogenic fluid, such as air, coupled to the first lumen, to inflate the inner balloon. In other embodiments the assembly is provided with a coupling for coupling a source of fluid to the inner balloon. The source of air may be a syringe.
The inner balloon may be made of a compliant material, in some embodiments of an elastomeric material. The inner balloon may be made of polyurethane or polyether block amide, for example.
There may be provided an implantable medical device carried on the balloon assembly, such as a stent or stent graft.
According to another aspect of the present invention, there is provided a balloon catheter assembly including: a carrier catheter having a distal end and a proximal end, at least first and second lumens passing through the catheter; a balloon assembly including an inner inflatable balloon attached in fluid tight manner at the distal end of the carrier catheter, the inner balloon providing an inner chamber; and an outer inflatable balloon disposed concentrically over the inner balloon, the outer balloon being attached in fluid tight manner at the distal end of the catheter and providing an outer chamber; the first lumen of the catheter including an outlet fluidically coupled to the inner chamber, the second lumen of the catheter including an outlet fluidically coupled to the outer chamber, whereby the inner and outer balloons are independently inflatable; wherein the outer balloon is wrapped over the inner balloon prior to inflation and wherein inflation of the inner balloon does not cause unwrapping of the outer balloon.
According to another aspect of the present invention, there is provided a balloon catheter assembly including: a carrier catheter having a distal end and a proximal end, at least first and second lumens passing through the catheter; a balloon assembly including an inner inflatable balloon attached in fluid tight manner at the distal end of the carrier catheter, the inner balloon providing an inner chamber; and an outer inflatable balloon disposed concentrically over the inner balloon, the outer balloon being attached in fluid tight manner at the distal end of the catheter and providing an outer chamber; the first lumen of the catheter including an outlet fluidically coupled to the inner chamber, the second lumen of the catheter including an outlet fluidically coupled to the outer chamber, whereby the inner and outer balloons are independently inflatable; and a source of air connected to the first catheter lumen for inflating the inner balloon with air.
Other features and advantages of the teachings herein will become apparent from the specific description which follows.
Embodiments of the present invention are described below, by way of example only, with reference to the accompanying drawings, in which:
It is to be understood that the drawings are schematic only and not to scale. They are intended to depict the major components of the devices taught herein and minor or ancillary components are not shown for the sake of clarity. The skilled person will be well acquainted with the typical dimensions and proportions suitable for the components and devices shown in the drawings, particularly having regard to the accompanying description.
Referring first to
By the distal end 14 of the catheter 12 there is provided a balloon structure 20, described in further detail below. At its proximal end 16 the catheter 12 includes three feed ports 22, 24, 26 which feed respectively into associated lumens 28, 30, 32 (shown in
The other lumens 28, 30 extend to the balloon structure 20 of the assembly 10 and are used to feed fluid into the two balloons of the structure 20, described in further detail below.
The catheter 12 can be made of any known and suitable material such as polyurethane, Nylon, silicone, polyethylene terephthalate and so on. The catheter 12 may be made solely of such materials but may also, as is common, include one or more strengthening elements within the structure of the catheter, such as a braided wire or coil. Such strengthening elements, particularly in larger diameter catheters, can assist in the pushability of the catheter through the patient's vasculature and in preventing kinking of the catheter.
Referring now to
The structure 20 also includes an outer balloon 70, which in this embodiment also has a generally conventional shape, that is a generally cylindrical body portion 72 bounded by end cones 74 and 76 and having proximal and distal necks 78, 80 fixed in fluid-tight manner to the catheter 12. The outer balloon 70 has an internal chamber 82 which is principally the volume between the inner wall surface of the outer balloon 70 and the outer wall surface of the inner balloon 40.
The catheter 12 includes an opening or port 90 which is fluidically coupled to the lumen 30 of the catheter 12. The port 90 opens to the chamber 82 of the outer balloon 70.
The balloons 40 and 70 can be fixed to the catheter 12 in any known manner, for instance by heat bonding, by use of an adhesive or other bonding agent, and so on.
As will be seen in
As can be seen in
In a practical embodiment, the inner balloon may have an inflated diameter of no more than 2 millimetres and in some embodiments of no more than 1.5 millimetres. For example, for a PTA balloon having an inflated diameter of 8 to 10 millimetres, the inner balloon may have an inflated diameter of 0.8 to 1.5 millimetres at most.
Referring now to
In use, the balloon catheter assembly 10 is fed endoluminally through a patient's vasculature from a remote percutaneous entry point with the balloon structure 20 in the deflated condition. This is typically done within an outer sheath as is known in the art. Once the distal end 14 of the assembly 10, and specifically the balloon structure 20, is positioned at the treatment site, the inner balloon 40 is inflated with air or other echogenic fluid by a suitable fluid supply, thereby to provide a volume of echogenic fluid within the chamber 52. This enables the structure 20 to be visualised by ultrasonic imaging. As a result, the location of the inner balloon 40 can be accurately determined during ultrasonic imaging. As a result of the preferred symmetrical disposition of the inner balloon 40 in the outer balloon 70, the position of the outer balloon can be directly established on visualising the inner balloon 40. This enables precise positioning of the balloon structure 20 at the desired treatment site. Once accurately positioned, the outer balloon 70 is inflated by injecting suitable inflation fluid, typically saline or other known solution, until it attains its deployed configuration and able to effect the medical treatment. The inner balloon 40 can be deflated when the outer balloon 70 is inflated or left in the inflated condition.
Until the outer balloon 70 is fully inflated, the assembly can therefore be moved proximally or distally in the vessel as necessary, since the inflation of the inner balloon is insufficient to cause unwrapping of the outer balloon 70. In this regard, it is also possible to deflate the inner balloon 40 after only the inner balloon 40 has been inflated, with such deflation allowing the outer balloon 70 to contract again as a result of the retention of the folds 100 in the wrapped balloon 70 and the natural resiliency of the material of the outer balloon 70.
It will be appreciated that the structure 20 is particularly compact in the longitudinal dimension. It also has the advantage of housing the inflatable balloon 40 entirely within the outer balloon 70. In this manner, should the inner balloon burst, the fluid used to inflate the inner balloon will remain within the chamber of the outer balloon 70 without escaping into the patient's blood stream. It should be noted, however, that the volume of air within the chamber 52 of the inner balloon 40 can be significantly less than a maximum safe threshold of air. Therefore, even were the air to escape from the inner balloon 40 this will not pose a health risk. The skilled person will in any event appreciate that the inner balloon 40 is not likely to burst as a result of the protection provided by the outer balloon 70. The arrangement also permits the use of a thin walled inner balloon 40, with the result that the structure 20 can be made more compact when wrapped to the catheter 12.
In practice, air can be fed into the chamber 52 of the inner balloon 40 by any suitable inflation source, a common syringe being an option.
The inner and outer balloons 40, 70 can be made of any known materials including, for example, a polyether block amide such as Pebax™, polyethylene terephthalate (PETE), a polyamide such as Nylon, or other suitable materials. The inner balloon can be made of the same material as the outer balloon or of compliant material, including polyurethane, silicone and the like.
Referring now to
As is shown in
The outer balloon 170 is shown in its wrapped condition, similar to the condition shown in
As is shown in
As with the first described embodiment, the inner balloon 140 can be left inflated or otherwise deflated during the inflation of the outer balloon 170.
It will be appreciated also that the bulging of the inner balloon 140 helps to retain the stent 150 precisely on the balloon assembly 120 during the initial phase of opening out of the crimped stent 150 and until the inner balloon 170 applies sufficient pressure to hold the opening stent 150 thereto.
The assembly 110 could be used in the deployment of other types of medical device, including, for example, stent grafts and so on.
It will be appreciated that the balloons of the balloon assemblies 20 and 120 are non-porous, so that they each retain fluid in their respective chambers.
It will also be appreciated that the arrangement of concentrically arranged balloons does not necessarily lengthen the balloon structure 20, such that the outer balloon 70, 170 can be chosen to be of a length optimal for the medical treatment to be carried out by the device.
The teachings herein are applicable to PTA balloons. These may have a smooth outer surface but may equally be textured, roughened and/or provided with one or more cutting or scoring elements.
The inflated shapes of the balloons of the balloon assemblies 20 and 120, shown particularly in
All optional and preferred features and modifications of the described embodiments and dependent claims are usable in all aspects of the invention taught herein. Furthermore, the individual features of the dependent claims, as well as all optional and preferred features and modifications of the described embodiments are combinable and interchangeable with one another.
The disclosures in British patent application number 1422607.0, from which this application claims priority, and in the abstract accompanying this application are incorporated herein by reference.
Number | Date | Country | Kind |
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GB1422607.0 | Dec 2014 | GB | national |