Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Arterial prosthesis – Stent structure
Reexamination Certificate
1999-06-30
2001-04-03
Nguyen, Dinh X. (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Arterial prosthesis
Stent structure
C623S001110, C623S001160, C623S001180, C623S001220
Reexamination Certificate
active
06210432
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention generally relates to a device and a method for treatment of mitral insufficiency and, more specifically, for treatment of dilatation of the mitral annulus.
Mitral insufficiency can result from several causes, such as ischemic disease, degenerative disease of the mitral apparatus, rheumatic fever, endocarditis, congenital heart disease and cardiomyopathy. The four major structural components of the mitral valve are the annulus, the two leaflets, the chordae and the papillary muscles. Any one or all of these in different combinations may be injured and create insufficiency. Annular dilatation is a major component in the pathology of mitral insufficiency regardless of cause. Moreover, many patients have a mitral insufficiency primarily or only due to posterior annular dilatation, since the annulus of the anterior leaflet does not dilatate because it is anchored to the fibrous skeleton of the base of the heart.
Studies of the natural history of mitral insufficiency have found that totally asymptomatic patients with severe mitral insufficiency usually progress to severe disability within five years. At present the treatment consists of either mitral valve replacements or repair, both methods requiring open heart surgery. Replacement can be performed with either mechanical or biological valves.
The mechanical valve carries the risk of thromboembolism and requires anticoagulation, with all its potential hazards, whereas biological prostheses suffer from limited durability. Another hazard with replacement is the risk of endocarditis. These risks and other valve related complications are greatly diminished with valve repair.
Mitral valve repair is theoretically possible if an essentially normal anterior leaflet is present. The basic four techniques of repair include the use of an annuloplasty ring, quadrangular segmental resection of diseased posterior leaflet, shortening of elongated chordae, and transposition of posterior leaflet chordae to the anterior leaflet.
Annuloplasty rings are needed to achieve a durable reduction of the annular dilatation. All the common rings are sutured along the posterior mitral leaflet adjacent to the mitral annulus in the left atrium. The Duran ring encircles the valve completely, whereas the others are open towards the anterior leaflet. The ring can either be rigid, like the original Carpentier ring, or flexible but non-elastic, like the Duran ring or the Cosgrove-Edwards ring.
Effective treatment of mitral insufficiency currently requires open-heart surgery, by the use of total cardiopulmonary by-pass, aortic cross-clamping and cardioplegic arrest.
To certain groups of patient, this is particular hazardous. Elderly patients, patients with a poor left ventricular function, renal disease, severe calcification of the aorta, previous cardiac surgery or other concomitant diseases, would in particular most likely benefit from a less invasive approach, even if repair is not complete. The current trend towards less invasive coronary artery surgery, without cardiopulmonary by-pass, as well as PTCA will also call for a development of a less invasive method for repair of the often concomitant mitral insufficiency.
SUMMARY OF THE INVENTION
Therefore, a first object of the present invention is to provide a device and a method for treatment of mitral insufficiency without the need for cardiopulmonary by-pass and opening of the chest and heart.
A second object of the invention is to provide reduction of the mitral annulus using less invasive surgery.
These and other objects are attained by a device as defined in the appended claim
1
, and by a method as defined in the appended claim
7
.
According to the present invention, a device for treatment of mitralis insufficiency comprises an elongate body having such dimensions as to be insertable into the coronary sinus and having two states, in a first state of which the elongate body has a shape that is adaptable to the shape of the coronary sinus, and to the second state of which the elongate body is transferable from the said first state assuming a reduced radius of curvature, whereby the radius of curvature of the coronary sinus is reduced as well as the circumference of the mitral valve annulus, when the elongate body is positioned in the coronary sinus.
Preferably, means are provided for the transfer of the elongate body to the second state by bending and/or shortening it from a larger radius of curvature to a smaller radius of curvature.
The transfer means may comprise means for bending and/or shortening the elongate body by a preferably asymmetric contraction thereof.
Further, the elongate body may comprise a memory material providing the transfer to the second state.
In a preferred embodiment, the elongate body may comprise a stent. In an alternative embodiment, the device according to the invention may comprise several stent sections and said bending and/or shortening means may comprise wires for shortening the distance between the stent sections.
According to a second aspect, a method of reducing the circumference of the mitral valve annulus comprises the steps of inserting an elongate body into the coronary sinus in the vicinity of the posterior leaflet of the mitral valve, and then providing a bending and/or shortening of the elongate body when positioned in the coronary sinus so as to reduce the curvature of the coronary sinus and thereby reduce the circumference of the mitral valve annulus.
Thus, the present invention takes advantage of the position of the coronary sinus being close to the mitral annulus. This makes repair possible by the use of current catheter-guided techniques.
The coronary veins drain blood from the myocardium to the right atrium. The smaller veins drain blood directly into the atrial cavity, and the larger veins accompany the major arteries and run into the coronary sinus which substantially encircles the mitral orifice and annulus. It runs in the posterior atrioventricular groove, lying in the fatty tissue between the left atrial wall and the ventricular myocardium, before draining into the right atrium between the atrial septum and the post-Eustachian sinus.
In an adult, the course of the coronary sinus may approach within 5-15 mm of the medial attachment of the posterior leaflet of the mitral valve. Preliminary measurements performed at autopsies of adults of normal weight show similar results, with a distance of 5,3±0,6 mm at the medial attachment and about 10 mm at the lateral aspect of the posterior leaflet. The circumference of the coronary sinus was 18,3±2,9 mm at its ostium (giving a diameter of the posterior leaflet of 5,8±0,9 mm) and 9,7±0,6 mm along the lateral aspect of the posterior leaflet (corresponding to a diameter of 3,1±0,2 mm).
REFERENCES:
patent: 5876419 (1999-03-01), Carpenter et al.
patent: 5980552 (1999-11-01), Pinchasik et al.
patent: 6027525 (2000-02-01), Suh et al.
Kimblad Per Ola
Solem Jan Otto
Browdy and Neimark
Nguyen Dinh X.
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