External venous valve stents for the correction of incompetent venous valves

Abstract

Improvements to external stents to render incompetent venous valves competent are disclosed. The device is an inelastic bio-compatible cuff that encircles the venous valve cusps decreasing the internal diameter of the vein wall to allow apposition of the cusps and create competence. The improvements over previous designs include the addition of calibrated known diameters to create competence for different phenotypes. The different diameters are indicated by holes in the body. The buckle attachment allows the body of the device to become conical or inverted to become pyramidal as appropriate. The buckle is wider than prior art designs to allow the device to become elliptical at smaller diameters. The angle of the notches in the device are approximately 150 to allow better overriding at the sapheno-femoral junction which allowing for better competence of the valve.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application is a divisional of U.S. patent application Ser. No. 10 / 472,460, filed Feb. 13, 2004, which claims priority to International Patent Application No. PCT / AU02 / 00361, filed Mar. 21, 2002, which claims priority to Australian Patent Application No. PR 3892, filed Mar. 23, 2001.FIELD OF INVENTION[0002]This invention relates to the correction of incompetent venous valves.BACKGROUND OF THE INVENTION[0003]Venous valves in mammals are usually bicuspid valves, with each cusp forming a sack or reservoir for blood which, under pressure, forces the free edges of the cusps together to prevent retrograde flow of the blood and allow only antegrade flow to the heart. When an incompetent valve attempts to close in response to a pressure gradient across the valve, the cusps do not seal properly and retrograde flow of blood occurs.[0004]There are two chronic venous diseases in which incompetence of venous valves is thought to be an important f...

AI Technical Summary

Benefits of technology

The venous valve cuff effectively restores competence to incompetent valves by resisting compressive forces and maintaining valve closure, delaying or preventing the progression of venous diseases by adjusting the vein diameter and minimizing further dilatation, thus improving the cosmetic and functional outcomes in patients with varicose veins and chronic deep venous insufficiency.

Problems solved by technology

When an incompetent valve attempts to close in response to a pressure gradient across the valve, the cusps do not seal properly and retrograde flow of blood occurs.

The varicose vein condition consists of dilatation and tortuosity of the superficial veins of the lower limb and resulting cosmetic impairment, pain and ulceration.

The initial defect in secondary varicose veins is often incompetence of a venous valve secondary to hypertension in the deep venous system.

Since this increased pressure is manifested at many points, correction of one site of incompetence could clearly be insufficient as other sites of incompetence will be prone to develop.

Once the initial incompetence occurs, incompetence in other valves in the system will tend to occur secondary to the venous hypertension.

Dilatation of the vein wall, whether idiopathic (primary varicose veins) leads to valvular incompetence.

This dilatation may eventually lead to stretching and sclerosis of the valve.

Other valves in the system will tend to become incompetent as the reflux of blood causes dilatation of the vein wall.

Even if the vein wall weakness is generalized as appears to be the case with primary varicose veins, correction of the initial defect will delay or prevent stress being placed no that wall and thus hinder progression of the disease.

Hallberg's method could not restore competence to the majority of the incompetent venous valves.

Therefore, DACRON™ polyester cannot alone be considered biocompatible.

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