GB2502956A

GB2502956A - A catheter having balloons located around the circumference of the catheter

Info

Publication number: GB2502956A
Application number: GB201209940A
Authority: GB
Inventors: Morgan Tierney
Original assignee: Creagh Medical Ltd
Current assignee: Creagh Medical Ltd
Priority date: 2012-06-06
Filing date: 2012-06-06
Publication date: 2013-12-18
Also published as: GB201209940D0

Abstract

A balloon catheter for dilation of a blood vessel comprises a catheter tube having an distal end and a proximal end, the catheter tube comprising an inner guidewire tube, an outer tube disposed concentrically about the inner guidewire tube, and an inflation lumen disposed there between. At least three expandable peripheral balloons are disposed at the distal end of the catheter tube, each expandable peripheral balloon being coextensive with a portion of a distal end of the guidewire tube and having a proximal end secured to the outer tube and in fluid communication with the inflation lumen and a distal end secured to the inner guidewire tube, and in which the at least three expandable peripheral balloons are equally spaced about the periphery of the inner guidewire tube.

Description

A balloon catheter, and use thereof for dilation of blood vessels

Technical Field

The invention relates to a balloon catheter of the type employed for dilation of blood vessels and other anatomical lumen typically dilated with balloon catheters such as biliary and urinary ducks, and sclerotic flyer in TIPS procedures. In particular, the invention relates to ultra-high pressure balloon catheter, and the use thereof in the dilation of blood vessels such as iliofemoral veins and arteries, and arterio-venous shunts.

Background to the Invention

Balloon catheters are conventionally employed for the dilation of constricted or narrowed blood vessels. They generally comprise a catheter tube having an inner guidewire tube, an outer tube, and an inflation lumen disposed between the inner and outer tubes. The catheter tube carries an expandable polymer balloon disposed its distal end, the balloon having a proximal end secured to the outer tube and a distal end secured to the inner tube, so that the inflation lumen is in fluid communication with the balloon for expansion thereof. In use, a surgeon makes an incision in the blood vessel and inserts a sheath into the vessel. The surgeon then inserts a guidewire into a patients blood vessel through the sheath, and passes the guidewire along the blood vessel to a target region of the vessel to be treated. The catheter tube is then inserted into the blood vessel, along the guidewire, until the balloon reaches the target region of the blood vesseL Once in place, the surgeon than passes an inflation fluid, typically saline solution, into the inflation lumen via a luer disposed at a proximal end of the catheter tube to inflate the balloon. Inflation of the balloon causes the target region of the blood vessel to dilate. This procedure is often employed in the case of plaque-burdened or constricted arteries, for example coronary arteries, to dilate the constriction, or is employed during a stenting procedure, where the vessel needs to be first widened prior to insertion of the stent, and once the stent is deployed the balloon is reinserted and inflated within the stent to expand the stent and secure it in position. This involves an iterative insertion, removal and reinsertion procedure which can be uncomfortable for the patient.

Balloon catheters are required for dilation of blood vessels having a range of diameters, from 1.5 mm to 32mm, and for clinical procedures that require a range of dilation pressures. For dilation of any balloon, a certain inflation pressure is required to achieve effective dilation of the blood vessel, and the inflation pressure informs the thickness of the balloon wall that is required to allow inflation to the desired pressure without the balloon bursting. It will be appreciated that as the thickness of the balloon wall increases, the diameter (profile) of the balloon in a deflated state increases, and this requires the surgeon to use a larger sheath for insertion and removal of the balloon, causing increased discomfort for the patient (See comparative Figs A). Additionally, larger profile balloon catheters can be more difficult to track over the guide wire through vascular tortuocity. Thus, there is an increasing need amongst surgeons for balloon catheters which are capable of operating at high pressures in large diameter vessels, but which are capable of being used with smaller sheaths.

One solution to this problem is the use of fibre reinforced balloon walls, as this allows the design of balloons with higher rated burst pressures but without significant increase of the balloon wall thickness. Such reinforced balloons are described in U56746425, US7309324, US7927443 and US6l56254. 1-lowever, the manufacture of such reinforced balloons is expensive and in many cases complicated.

It is an object of the invention to overcome at least one of the above-referenced problems.

Statements of Invention

The invention relates to a balloon catheter that is capable of maintaining the high performance and thin wall characteristics of a smaller balloon while achieving a larger dilation diameter. This is achieved by providing at least three balloons on the catheter instead of one, the balloons being arranged in a generally parallel disposition about a distal end of the guidewire tube. The use of at least three balloons instead of one allows the volume of each balloon to be minimised while still achieving an increased dilation diameter due to the composite effect of the at least three balloons, As the volume of each balloon is minimised, the wall thickness of each balloon does not need to be increased, and this ensures that the deflated diameter (profile) is not increased. The balloons are arranged in a generally parallel anangement about the inner guidewire tube, and are typically equally spaced about the guidewire tube. At least three balloons is desired as this ensures that the dilation pressures exerted on the blood vessel are spread out around the vessel, as compared with the situation where two balloons are employed which would result in uneven pressures being deployed, and pressure being exerted on the point of least resistance within the vessel.

Accordingly, in a first aspect. the invention broadly provides a balloon catheter for dilation of a blood vessel or a like vessel or tube, and comprising a catheter tube having a distal end and a proximal end, the catheter tube comprising an inner guidewire tube, an outer tube disposed concentrically about the inner guidewire tube, and an inflation lumen disposed there between, and at least three expandable peripheral balloons disposed at the distal end of the catheter tube, each expandable peripheral balloon being coextensive with a portion of a distal end of the guidewire tube and having a proximal end secured to the outer tube and in fluid communication with the inflation lumen and a distal end secured to the inner guidewire tube, and in which the at least three expandable peripheral balloons are preferably equally spaced about the periphery of the inner guidewire tube.

Preferably, the balloon catheter of the invention comprises, in addition to the at least three expandable peripheral balloons, an expandable center balloon disposed about the inner guidewire tube and generally co-extensive with the three inflation balloons. The center balloon suitably has a distal end secured to the outer tube and a proximal end secured to the inner guidewire tube. It will be appreciated that in this embodiment, the distal end of the at least three expandable peripheral balloons may be adhered to the inner guidewire tube or a distal end of the center balloon where it is adhered to the inner guidewire tube.

Typically, the balloon catheter comprises at east 4. 5, 6, 7, 8. 9, or 10 expandable peripheral balloons, that may be arranged about the inner guidewire tube or arranged about the center balloon.

Suitably, the balloon catheter has an inflation diameter of at least 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, 20mm, 21mm, 22mm, 23mm, or 24mm, and is optionally capable of being inserted in SF sheath when in a deflated state.

Preferably, the balloon catheter has an inflation diameter of at east 12mm and is capable of being inserted in 6F sheath when in a deflated state.

Typically, the balloon catheter has an inflation diameter of at least 14mm and is capable of being inserted in 7F sheath when in a deflated state.

Suitably, the balloon catheter has an inflation diameter of at least 18mm, 19mm, 20mm, 21mm, 22mm, 23mm or 24mm and a rated burst pressure of at least 2OATM, 2IATM or 22ATM.

Suitably, the balloon catheter has a rated burst pressure of at least I OATM. 11 ATM, I 2ATM.

13ATM, 14ATM, 15ATM, 16ATM, 17ATM, 18ATM, 19ATM or 2OATM, and is capable of being inserted in 6F. 7F or 8F sheath when in a deflated state.

In one embodiment, the balloon catheter has a rated burst pressure of at least I 5ATM and is capable of being inserted in 7F sheath when in a deflated state.

In another embodiment, the balloon catheter has a rated burst pressure of at least I2ATM and is capable of being inserted in 8F sheath when in a deflated state.

In a further aspect, the invention relates to a balloon catheter of the invention for use in dilation of a blood vessel, for example a vein or an artery. Typically, the blood vessel has a diameter of at least 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, 20mm, 21mm, 22mm, 23mm or 24mm.

In a further aspect, the invention relates to a balloon catheter of the invention for use in dilation or stenting ofa large blood vessel.

In a further aspect, the invention relates to a balloon catheter of the invention for use in dilation or stenting of an iliofemoral vein.

In a further aspect, the invention relates to a balloon catheter of the invention for use in an angioplasty procedure.

In a further aspect, the invention relates to a balloon catheter of the invention for use in a stenting procedure.

In a further aspect, the invention provides a balloon catheter suitable for use with blood vessels and comprising a catheter tube having a guidewire lumen and an inflation lumen, and at least three expandable balloons disposed around a distal end of the catheter tube in a generally parallel aiTangement to the catheter tube, each balloon being in fluid communication with the inflation lumen for inflation and deflation thereof.

The letter "F" in 5F an art-recognised term meaning "French" and refers to the size of the sheath introducer employed during insertion and removal from a blood vessel during an interventional procedure. For example sheaths 4F to 8F sheaths have internal diameters ranging from i.35mmto 2.7mm, respectively The term "rated burst pressure" or "RBP" should be understood to mean the pressure at which 999% of balloons can survive with 95% confidence. A suitable method of measuring balloon burst pressure is by inflating the test catheter as described in Iso 10555-4:1997 Annex A sections A.l to A.3.3 with a deviation to A.3.3 wherein the balloon is taken to a pressure which results in a balloon burst.

The term "blood vessel" should be understood to mean a vascular lumen that caiTies blood either away from or toward the heart. Examples of blood vessels include the iliac. femoral, and subclavian arteries and veins, the aorta and vena cava, prosthetic bypass grafts, and arterio-venous shunts for dialysis. While the invention as described above is intended for use with blood vessels, it will be appreciated that the invention may also be employed for use in other anatomical lumen, for example. biliary and urinary ducts, sclerotic liver tracts in TIPS procedures, tracheal-bronchial passages, the esophagus. and nasal passages.

Brief Description of the Figures

The invention will be more cleary understood from the following description of some embodiments thereof, given by way of example only, with reference to the accompanying figures in which: Fig. A (comparative) are images of a cut section of a thick wall (Fig. A.l) and thin walled (Fig. A.2) balloon in a deflated, wrapped, state within a vessel; Fig. 1 is a perspective view of a balloon catheter of the invention having three expandable peripheral balloons around a distal end of the inner guidewire lumen; Figs.2A to 2D are sectional illustrations of four alternative embodiments of the balloon catheter of the invention, having (a) four expandable peripheral balloons arranged about a center balloon, b) eight expandable penpheral balloons arranged about a center balloon, (c) three expandable peripheral balloons alTanged about an inner guidewire lumen, and D) five expandable peripheral balloons arranged about an inner guidewire umen.

Detailed Description of the Invention

Percutaneous transluminal angioplasty (PTA) or angioplasty is a method of treating blood vessel disease. A catheter with a deflated balloon on its tip is positioned in a narrowed artery segment. Inflation of the balloon with pressure through the injection of a mixture of saline and contrast material dilates the narrowed blood vessel opening the narrowed segment 1.Recent technology and procedural advances have lead to the demand for larger balloons to treat larger diameter vessels. However mechanical fundamentals have provided an additional challenge in terms of balloon performance requirements. This challenge sterns frorn the requirements for the effects if ba'loon diameter on balloon burst pressure.

The stress on a balloon wall during balloon inflation can be estimated through the following equation: sr = pd/2t s I = pd/4t Where: p = pressure, d = diameter, t = thickness, sr = hoop or radial stress, si = axial or longitudinal stress From the above equation, the radial tensile strength of a balloon can be easily calculated as follows: TS = pdl2t Where: TS = calculated radial tensile strength p = burst pressure, d = diameter, t =wall thickness Per the above equation the radial stress or hoop stress is twice the longitudinal stress; therefore, when a balloon fails, it normally splits along its length rather than circumferentially. When larger balloons are designed the corresponding wall thickness must be increased to maintain high burst pressures. By increasing the balloon diameter and the balloon wail thickness the overa'l balloon wrapped profile increased exponentially due to the increase in material (or Balloon Cross sectional Area). In order for catheter designers to provide large dilation diameters with high rated burst while maintaining acceptable wrapping profiles. the Applicant provides a way of utilising the performance of smaller diameter balloons to address this challenge.In this approach, the Applicant has created a larger dilation using a configuration of smaller balloons and positioning the smaller balloons in parallel on the catheter. In this configuration it is possible maintain the high performance and thin wall characteristics of the sma'ler balloon but achieve a larger dilation diameter by using a series of these smaller balloons.

Example I

Referring to the Figures, and initially to Fig. 1, there is illustrated a balloon catheter according to the invention, indicated generally by the reference numeral 1, and comprising a catheter tube 2 having a proximal end (not shown) and a distal end 3. The tube comprises an inner guidewire tube 4 and an outer tube 5. and an inflation lumen (not shown) between the inner and outer tubes. The inner guidewire tube 4 extends along the length of the catheter tube, whereas the outer tube 5 terminates short of the end of the catheter tube, exposing a distal portion of the guidewire tube 4a. Three expandable balloons 6 are provided on a distal end of the catheter tube 2, arranged generally parallel to and generally co-extensive with the exposed portion of the guidewire tube 4a. Each balloon has a central portion 10, and a proximal and distal neck portion II, 12 at each end of the central portion. The proximal neck portion 11 is secured to the outer tube 4 such that it is in fluid communication with the inflation lumen, and the distal neck portion 12 is secured to the inner guidewire tube.

Example 2

Referring to Fig.2, there are illustrated four alternative embodiments of balloon catheters according to the invention, in which parts identified previously are assigned the same reference numerals. Refernng initially to Fig. 2A, there is illustrated a balloon catheter having four expandable balloons 6 disposed about a center balloon 20. In this embodiment, the center balloon is formed around the guidewire tube (not shown), and the four peripheral balloons 6 are equally spaced around the center balloon 6. The center balloon is arranged in a conventional manner, with a proximal neck portion secured to the outer tube and a distal neck portion secured to inner guidewire tube. Fig. 2B illustrates a similar balloon catheter as that described with reference to Fig. 2A. in which the eight peripheral balloons 6 are provided around the center balloon 20. Figs. 2C and 2D disclose a further embodiment having three expandable balloons 6 (Fig. 2C), or five expandable balloons 6 lFig. 2D) and no central balloon.

Example 3

Three preformed 6mm * 60mm nylon balloons were configured in a parallel arrangement as shown in Fig. 3 Each balloon contained a flex iNc PTFE mandrel which travelled through the entire balloon exiting at the distal and proximal necks as shown in Fig. 4. PEP Heat shrink is then loaded over the balloon necks as shown in Fig.5. The balloon necks are then reshaped and bonded through activation of the heat shrink via hot air at i9O as shown in Fig. 6.

Following cooling the heat shrink and mandrels are removed. With the mandrel removed each balloon inner chamber can be inflated and deflated via the path left by the mandrel, as shown in Fig. 7.

Example 4

Balloon Bodies were prepared by cutting away the baBoon necks and cones as shown in Fig. 8. Three preformed 6mm * 60mm nylon balloon bodies were folded and configured on a 0.035" mandrel in parallel alTangement as shown in Fig. 9. Each folded body contains a flat teflon mandrel travelling within its inner lumen over its entire length.

Refening to Fig. 10, FEP heat shrink is then loaded over each end of the balloon bodies encasing the mandrels and wrapped balloon. The balloon heated sections are then reshaped and bonded through activation of the heat shrink via hot air at 190°C. Following cooling the heat shrink and mandrels are removed. With the mandrel removed each balloon inner chamber can be inflated and deflated via the path left by the mandrel (Fig. 11).

The invention is not limited to the embodiment hereinbefore described which may be varied in constnzction and detail without departing from the spiring of the invention.

Claims

Claims 1. A balloon catheter for dilation of a blood vessel and comprising a catheter tube having an distal end and a proximal end, the catheter tube comprising an inner guidewire tube, an outer tube disposed concentrically about the inner guidewire tube, and an inflation lumen disposed therebetween, and at least three expandable penpheral balloons disposed at the distal end of the catheter tube, each expandable peripheral balloon being coextensive with a portion of a distal end of the guidewire tube and having a proximal end secured to the outer tube and in fluid communication with the inflation lumen and a distal end secured to the inner guidewire tube, and in which the at least three expandable peripheral balloons are equally spaced about the periphery of the inner guidewire tube.
2. A balloon catheter as claimed in Claim 1 additionally having a expandable center balloon disposed about the inner guidewire tube and generally co-extensive with the three inflation balloons, the center balloon having a distal end secured to the outer tube and a proximal end secured to the inner guidewire tube.
3. A balloon catheter as claimed in Claim 1 or 2 having at least four expandable peripheral balloons.
4. A balloon catheter as claimed in Claim 1 or 2 having at least five expandable penpheral balloons.
5. A balloon catheter as dairned in Claim I or 2 having at least six expandable peripheral balloons.
6. A ballon catheter as claimed in any preceding Claim having an inflation diameter of at least 8mm and capable of being insered in SF sheath when in a deflated state.
7. A ballon catheter as claimed in any preceding Claim having an inflation diameter of at least 12mm and capable of being inserted in 6F sheath when in a deflated state.
8. A ballon catheter as claimed in any preceding Claim having an inflation diameter of at least 14mm and capable of being inserted in 7F sheath when in a deflated state.
9. A ballon catheter as claimed in any preceding Claim having an inflation diameter of at least 18mm and a rated burst pressure of at least 2OATM.
10. A ballon catheter as claimed in any preceding Claim having an inflation diameter of at least 20mm and a rated burst pressure of at least 2OATM.
II. A ballon catheter as claimed in any preceding Claim having an inflation diameter of at least 22mm and a rated burst pressure of at least 2OATM.
12. A balion catheter as claimed in any preceding Claim having a rated burst pressure of at least I OATM and capable of being inserted iii 6F sheath when in a deflated state.
13. A balion catheter as claimed in any preceding Claim having a rated burst pressure of at least 15ATM and capable of being inserted in 7F sheath when in a deflated state.
14. A balon catheter as claimed in any preceding Claim having a rated burst pressure of at least 2OATM and capable of being inserted in SF sheath when in a deflated state.
15. A balloon catheter suitable for use with blood vessels and comprising a catheter tube having a guidewire lumen and an inflation lumen, and at least three expandable balloons disposed around a distal end of the catheter tube in a generally parallel arrangement to the catheter tube, each balloon being in fluid coimunication with the inflation lumen for inflation and deflation thereof
16. A balloon catheter as claimed in any preceding Claim for use in dilation of blood vessels having a diameter of at least 10mm.
17. A balloon catheter as claimed in any preceding Claim for use in dilation of iliofemoral veins.
IS. A balloon catheter as claimed in any preceding Claim for use in a stenting procedure.
19. A method of dilating a blood vessel which employs a balloon catheter according to any of Claims Ito 15 that is located in a blood vessel of a patent with the at least three expandable peripheral balloons located at a target region of the blood vessel, the method comprising the steps of inflating the balloons at the target region to dilate the blood vessel at the target region.