Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Heart valve – Combined with surgical tool
Reexamination Certificate
2003-01-14
2004-12-14
Jackson, Suzette J. (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Heart valve
Combined with surgical tool
C623S904000
Reexamination Certificate
active
06830585
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a prosthetic valve for implantation in a body channel,more particularly, to a percutaneously implantable prosthetic heart valve suitable for replacement of a defect or diseased human heart valve and methods of implantation.
BACKGROUND OF THE INVENTION
Replacement heart valves or heart valve prostheses have been fabricated or manufactured for the last forty years. Such devices have been assembled from a variety of materials. Specifically the materials have been of biologic or artificial nature, generally leading to two distinct categories of the prostheses as biological or mechanical replacement heart valves.
The prosthetic heart valves are fabricated to replace the natural heart valves that,because of disease, congenital malformations, ageing or trauma have become dysfunctional and require repair to their functional elements or partial or complete replacement. Characteristics for a desirable prosthetic heart valve may include hemodynamic performance, thrombogenicity,durability and ease of surgical implantation.
Human heart valves under the conditions of normal physiological functions are passive devices that open under the pressure of blood flow on their leaflets. There are four valves in the heart that serves to direct the flow of blood through all chambers in a forward direction. In general, blood leaves the heart lower chambers in the direction to the rest of the body or to the lungs for required oxygenation, or blood enters the lower chambers from the upper chambers of the heart. Similarly, they close under the pressure exerted on the same leaflet elements when blood flow is retrograde, thus impeding return of blood flow to the chamber it has just left. This,under normal conditions, (that is, when the body is not under physical stresses and the heart is beating at the normal resting state of about 70 beats per minute) equates to the leaflets opening by separation from each other, thereby producing an opening or closing by apposing to each other approximately 38 million times per year. It can be surmised that under stress conditions this may be happening at higher rates, thus increasing the number of separations and appositions, as well as the forces of impact between the leaflets during the closing.
When disease conditions affect the structure of the materials of the components of the valve apparatus, the valve itself will decay, degenerate or disrupt and require repair or replacement to restore proper function necessary for the continuation of life.
The shape of the leaflet and surrounding elements of a valve or a valve apparatus is dependent on the function of the heart. In the case of the atrioventricular valves, otherwise known as mitral (in the left lower chamber of the heart) and tricuspid (in the right ventricle), the valve is part of a continuum that extends from the myocardium or muscular wall of the lower chambers,through the papillary muscles, to which is attached a confluence of tendinous rope-like elements known as
chordae tendinae
that themselves are attached to the edges of differently shaped leaflets which form the flow-allowing and flow-stopping or obstructing elements (leaflets). These leaflets continue and end at a ring-like structure usually known as annulus, that is part of the skeleton of the heart. It is this continuum which should be called an apparatus rather than just valve.
Thus, there is a tricuspid valve apparatus in the right ventricular chamber and more importantly the mitral valve apparatus within the lower left heart chamber or left ventricle, the pumping function of which provides the systemic flow of blood through the aorta, to keep all tissues of the body supplied with oxygenated blood necessary for cellular function and life.Hence during the cardiac cycle, the valves function as part of a unit composed of multiple interrelated parts, including the ventricular and atria walls, the valve leaflets, the fibrous skeleton of the heart at the atrioventricular ring, and the subvalvular apparatus. The subvalvular apparatus includes the papillary muscle within the ventricle, and the chordae tendinae which connect the papillary muscle to the valve leaflets.
Aortic and pulmonary valves have been replaced with simple trileaflet chemically treated biological valves obtained from animals, or bileaflet mechanical valves without extreme deficiencies in valvular or cardiac function. This is not the case when mitral or tricuspid valves are replaced and the necessary involvement of chordae tendinae and muscular element of the chamber wall are not united to function in harmony with the valve leaflets. Those valves used in the aortic position cannot alone replace the mitral valve apparatus without anatomical and functional compromise. The aortic and pulmonary valves are referred to as “semilunar valves” because of the unique appearance of their leaflets, which are shaped somewhat like a half-moon and are more aptly termed “cusps”. The aortic and pulmonary valves each have three cusps.
Aortic stenosis is a disease of the aortic valve in the left ventricle of the heart. This aortic valvular orifice can become tightly stenosed, and therefore the blood cannot anymore be freely ejected from the left ventricle. In fact, only a reduced amount of blood can be ejected by the left ventricle which has to markedly increase the ventricular chamber pressure to pass the stenosed aortic orifice. In such aortic diseases, the patients can have syncope, chest pain, and mainly difficulty in breathing. The evolution of such a disease is disastrous when symptoms of cardiac failure appear and many patients die in the year following the first symptoms of the disease.
The only commonly available treatment is the replacement of the stenosed aortic valve by a prosthetic valve via open-heart surgery. U.S. Patent Application publication 2002/0052651 to Myers et al., entire contents of which are incorporated herein by reference, discloses a tubular prosthetic semilunar or atrioventricular heart valve by adding substantially rectangular commissural mounting tabs or pads at the distal end. The commissural mounting tab is generally used for stitching or suturing onto the wall of the body channel.
If surgery is impossible to perform, i.e., if the patient is deemed inoperable or operable only at a too high surgical risk, an alternative possibility is to dilate the valve (that is, an endovascularly deliverable heart valve) with a balloon catheter to enlarge the aortic orifice.Unfortunately, the result is sub-optimal with a high restenosis rate or dysfunction for a conventional stented heart valve.
Aortic stenosis is a very common disease in people above seventy years old and occurs more and more frequently as the subject gets older. Until recently, the implantation of a valve prosthesis for the treatment of aortic stenosis is considered unrealistic to perform since it is deemed difficult to superpose another implantable valve on the distorted stenosed native valve without excising the latter.
Percutaneous Catheter-Based Delivery
Andersen et al. in U.S. Pat. No. 6,168,614, entire contents of which are incorporated herein by reference, discloses a heart valve prosthesis for implantation in the body by use of a catheter. The valve prosthesis is consisted of a support structure with a tissue valve connected to it, wherein the support structure is delivered in a collapsed shape through a blood vessel and secured to a desired valve location with the support structure in the expanded shape. However,the support structure tends to compressively impinge a portion of the leaflets of the tissue valve at the structure struts when the support structure is expanded by an inflatable balloon for positioning endovascularly. The impinged leaflets tend to deteriorate and calcify, making the valve useless.
Andersen et al. in U.S. Pat. No. 5,411,552, No. 5,840,081, and No. 6,168,614, entire contents of which three are incorporated herein by reference, discloses a system for implanting a valve in a body channel comprising a radially collapsible and expandabl
Artof Jason
Quijano Rodolfo C.
Tu Hosheng
3F Therapeutics, Inc.
Jackson Suzette J.
Jones Day
LandOfFree
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