VALVE

Abstract

An esophageal valve has a restriction to allow antegrade passage of swallowed food and controlled retrograde passage of fluid. The restriction comprises an iris having a number of folds.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application is a continuation-in-part of U.S. patent application Ser. No. 11/643,698 filed Dec. 22, 2006 which claims the benefit of U.S. Provisional Application No. 60/752,881 filed Dec. 23, 2005. The present application also claims the benefit of U.S. Provisional Application No. 61/074,384 filed Jun. 20, 2008. The complete contents of all of these are incorporated herein by reference.

INTRODUCTION

The invention relates to devices useful in the treatment of GERD (Gastro Esophageal Reflux Disease)

GERD is often caused by a failure of the anti-reflux mechanism. In healthy patients the anti-reflux mechanism is comprised of the lower esophageal sphincter (LES) and the “Angle of His,” the angle at which the esophagus enters the stomach. These create a valve that prevents duodenal bile, enzymes, and stomach acid from traveling back into the esophagus where they can cause burning and inflammation of sensitive esophageal tissue.

A surgical treatment, which is often preferred over longtime use of medication, is the Nissen fundoplication. In this procedure the upper part of the stomach is wrapped around the LES (lower esophageal sphincter) to strengthen the sphincter and prevent acid reflux and to repair a hiatal hernia. The procedure is usually carried out laparoscopically.

In 2000 the U.S. Food and Drug Administration (FDA) approved two endoscopic devices to treat chronic heartburn. In one system stitches are put in the LES to create pleats to strengthen the muscle. Another, the Stretta Procedure, uses electrodes to apply radio frequency energy to the LES. The long-term outcomes of both procedures compared to a Nissen fundoplication are still being determined.

The NDO Surgical Plicator is also used for endoscopic GERD treatment. The Plicator creates a plication, or fold, of tissue near the gastroesophageal junction, and fixates the plication with a suture-based implant. The Plicator is currently marketed by NDO Surgical, Inc.

STATEMENTS OF INVENTION

According to the invention there is provided an esophageal valve having a restriction to allow antegrade passage of swallowed food and controlled retrograde passage of fluid, the restriction comprising a iris having a number of folds.

In one embodiment the valve is adapted to be opened when different forces are applied in the antegrade and retrograde directions.

In one case the valve is adapted to open in the antegrade direction in response to antegrade forces and to open in the retrograde direction in response to retrograde forces, the retrograde force required to open the valve being substantially greater than the antegrade force required to open the valve.

In one embodiment the iris is formed from a tubular precursor, the ends of which are oppositely rotated. The precursor may be folded as the ends are oppositely rotated. In one case the precursor is generally cylindrical. In one case the precursor is generally of hourglass shape.

In one embodiment the restriction comprises at least three folds.

In one case the valve has means to set the differential forces required to open the valve.

The valve may comprise a stop to restrict the opening of the valve in one direction.

In one case the valve comprises strengthening means to restrict the opening of the valve in one direction.

In one embodiment the valve comprises a support for the iris.

In one case the tubular iris is attached to the support. The attachments may be arranged such that the valve will open in response to different forces applied in the antegrade and in the retrograde directions.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more clearly understood from the following description thereof given by way of example only, in which:

FIGS. 1 to 8 illustrate a valve of the invention in various configurations;

FIG. 9 is an isometric view of a valve device according to the invention;

FIG. 10 is a cross sectional view of the device of FIG. 9;

FIG. 11 is a plan view of a valve of with four folds;

FIG. 12 is a plan view of a valve with five folds;

FIG. 13 is a plan view illustrating the operation of the valve;

FIGS. 14 and 15 are cross sectional views of the valve in use; and

FIG. 16 is a cross sectional view of the valve in use.

DETAILED DESCRIPTION

The invention is a prosthetic esophageal valve, which prevents reflux from entering into the esophagus. The valve is specifically designed to allow swallowed food to pass distally through it and also to allow retrograde flow of liquid and gasses proximally during belching or vomiting.

FIGS. 1 to 8 illustrate a valve 1 in various configurations. The valve 1 comprises a sleeve 5 which is twistable to move the sleeve 5 between an open configuration (FIGS. 1 and 2) in which a lumen 6 is open, and a sealed configuration (FIGS. 7 and 8) in which the lumen is closed.

The implantable sleeve 5 could have an “hourglass” shape, as illustrated in FIGS. 1 to 8. This shape would enable the device to be located and secured at the oesophageal sphincter 25. In addition the device can be twisted in-situ by the clinician to tailor the elasticity of the orifice created. The sleeve 5 could be held in place either by sutures or by an adhesive.

FIGS. 1 to 8 illustrate the sleeve 5 designed as a sphincter implant with adjustable opening tightness.

Referring to FIGS. 9 to 16, in this case the middle of the valve has a restriction 10 that controls flow in both directions. The restriction 10 is formed through a series of folds 11 in the lumen of the valve, which are created by simultaneously rotating and folding a precursor as described above with reference to FIGS. 1 to 8.

The precursor component can be a straight tube or an hourglass shaped tube with an open lumen.

Additionally, the tube can have specific internal profiles such as helical ribs or protrusions. The proximal and distal opening forces can be varied by changing the internal profile of the valve or the conical angle at either end of the valve. The valve may be mounted to a semi-rigid support 20 such as a braided plastic stent. In this case there is a proximal mounting 26 and a distal mounting as illustrated particularly in FIG. 10. The degree of attachment may be varied to influence the characteristics of the valve. For example, the distal attachment 27 may be adapted to facilitate opening in response to a pre-determined retrograde force P₂ which will facilitate belching or vomiting. Similarly, the proximal attachment 26 may be adapted to facilitate opening in response to a pre-determined antegrade force P₁.

The restriction can be created by rotating the ends of the tubular precursor contrary to each other either clockwise or anticlockwise. This has the effect of creating an internal iris in the centre of the rotated tube. The iris thus created has a number of folds or wings, which are predetermined prior to rotation. The angle of rotation can be between 15 and 200°. The angle of rotation can be used to vary the force to be applied to pass through.

In addition, during the rotation of the tube it naturally foreshortens. The foreshortening effect can be controlled by applying longitudinal compression or tension.

When the target angle of rotation, number of folds and degree of foreshortening is achieved the iris can be locked into it's desired configuration by externally connecting it to a supporting structure 20. The restriction can be made from three or more folds. The helical angle of the internal ribs can be between 10 and 90° to the vertical.

The valve functions as a conformable iris in which the opening force can be predetermined through its geometric properties.

It is possible to make the valve open with different forces in the proximal and distal directions. For example, a re-inforcing ring may be placed at one side of the valve. This functions as a physical stop to reduce the freedom of movement of the iris wings in one direction. Alternatively or additionally the opening characteristics in response to antegrade and retrograde flow can be altered by providing additional layers or thicknesses of material at appropriate locations.

The conical sections 3, 4 act as a means to direct food through the lumen rather than around the outside of the device whereas the narrow restriction 2 in the middle of the valve functions as a means of preventing flow.

The force provided by the valve to restrict flow is dependent on a number of factors including:

the degree of restriction in the centre of the valve;

the angle or curvature between the end of the device and the central restriction;

whether the angle (or curvature) of the proximal and distal ends of the device are the same. Different angles will create different degrees of restriction in the proximal and distal directions;

the ‘pass through’ force can also be manipulated by changing the material properties from which the valve is made; and

the properties of the valve will also be influenced by the external forces placed upon it by the natural movement and pressure of the esophagus. This external force may augment the functioning of the valve by contributing to the degree of restriction.

The angle that the proximal end of the device makes with the restriction can be between 10 and 90° to the horizontal.

The luminal diameter of the restriction in the centre of the valve can be between 0 and 20 mm.

The elongation of the material used to construct the restriction can be between 50 and 3000%

The tensile strength of the material used to construct the restriction can be between 0.01 and 5 N/mm².

In order to facilitate the normal passage of food in the esophagus the restriction is capable of opening, in the proximal direction, with an axial force of between 50 and 100 g.

In order to facilitate normal belching and vomiting the restriction is capable of opening, in the distal direction, with a pressure of between 200 and 500 mmH₂O.

This design creates the optimum valve conditions while positioned in the lumen of the esophagus. Previous approaches have required devices to be placed either on the outside of the esophagus or under the mucosal surface tissue of the esophagus. Thus the current invention circumvents the need for invasive procedures.

The valve allows retrograde opening at precisely defined pressures.

Because the valve does not invert to facilitate belching and vomiting it does not have to reorient itself periodically.

Many variations of valve can be produced to treat varying severity of disease.

The device can also be made in a very low profile fashion to facilitate its crimping and subsequent delivery.

The valve of the invention requires very low actuation pressure. It can function asymmetrically to mimic the various bodily functions in the esophagus.

The valve may be of any suitable biocompatible materials that have characteristics as follows. The materials used for the production of this valve should have a % elongation between 50% and 3000%. Additionally the material could have an antimicrobial action to prevent colonisation when in-vivo. Additionally the material can be elastic or viscoelastic and can optionally be an open cell foam. The density of the material should be between 0.1 g/cm³ to 1.5 g/cm3.

The valve of the invention may be used to treat gastroesophageal reflux disease.

The invention is not limited to the embodiments hereinbefore described, which may be varied in detail.

Claims

1. An esophageal valve having a restriction to allow antegrade passage of swallowed food and controlled retrograde passage of fluid, the restriction comprising an iris having a number of folds.

2. A valve as claimed in claim 1 wherein the valve is adapted to be opened when different forces are applied in the antegrade and retrograde directions.

3. A valve as claimed in claim 2 wherein the valve is adapted to open in the antegrade direction in response to antegrade forces and to open in the retrograde direction in response to retrograde forces, the retrograde force required to open the valve being substantially greater than the antegrade force required to open the valve.

4. A valve as claimed in claim 1 wherein the iris is formed from a tubular precursor, the ends of which are oppositely rotated.

5. A valve as claimed in claim 4 wherein the precursor is folded as the ends are oppositely rotated.

6. A valve as claimed in claim 4 wherein the precursor is generally cylindrical.

7. A valve as claimed in claim 4 wherein the precursor is generally of hourglass shape.

8. A valve as claimed in claim 1 wherein the restriction comprises at least three folds.

9. A valve as claimed in claim 1 wherein the valve has means to set the differential forces required to open the valve.

10. A valve as claimed in claim 9 wherein the valve comprises a stop to restrict the opening of the valve in one direction.

11. A valve as claimed in claim 9 comprising strengthening means to restrict the opening of the valve in one direction.

12. A valve as claimed in claim 1 comprising a support for the iris.

13. A valve as claimed in claim 12 wherein the tubular iris is attached to the support.

14. A valve as claimed in claim 13 wherein a distal end of the tubular iris is attached to the support and a proximal end of the tubular iris is attached to the support.

15. A valve as claimed in claim 14 wherein the attachments are arranged such that the valve will open in response to different forces applied in the antegrade and in the retrograde directions.