Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Heart valve – Having rigid or semirigid pivoting occluder
Patent
1992-12-29
1995-05-16
Isabella, David
Prosthesis (i.e., artificial body members), parts thereof, or ai
Heart valve
Having rigid or semirigid pivoting occluder
A61F 224
Patent
active
054156670
DESCRIPTION:
BRIEF SUMMARY
This invention relates to mitral heart valve replacements.
Heart valve replacement and in particular mitral valve replacement devices fall into two broad categories, mechanical and bioprosthetic. Both kinds of device are obstructive to flow compared with the normal natural valve.
Mechanical valves of all kinds must be used with coumadin type anticoagulants: without this treatment there is a prohibitive risk of the formation of clots which will either obstruct the valve or break away to block vital arteries (e.g., arteries in the brain, leading to a stroke). Even with anticoagulants the risk of clotting and its complications remains. The durability of most mechanical valves is excellent.
Bioprosthetic valves (of treated biological tissue supported by a frame or stent) are less likely to be affected by clot formation but have less durability, inevitably developing calcification and/or tears with time, with this process being prohibitively accelerated in children.
The haemodynamics of the natural mitral valve are dependent on the absence of a stent, the absence of a rigid ring, the relatively unrestrained opening of the flaps and the flexibility of the tissues. The durability is dependent on the fact that it is living tissue capable of self regeneration. The absence of clotting problems is related to the living endothelium which is composed of special cells with properties that prevent local clot formation.
One object of the present invention is to provide an entirely flexible non-elastic bioincorporable unstented replacement mitral valve that has no rigid parts to project into the inner cavity of the ventricle.
Another object is to avoid the use of any metal or plastics stiffener in the circumferential part of the replacement valve that is to be sewn to the orifice of the ventricle.
A further object is to provide a replacement mitral heart valve in which the part to be fixed to the inlet orifice of the ventricle is an integral part of and is in continutity with the valve mechanism proper, and therefore:
a) has no bulk to detract from the effective orifice area of the valve;
b) has a smooth inflow into the orifice without any potential nooks and crannies or excrescence that can produce local stasis that leads to thrombus formation;
c) has no interface between bioincorporable and nonbioincorporable material that when it exists is always accompanied by clot formation;
d) allows healing to take place directly between the bioincorporable implant and the native tissue, thereby, ensuring a permanent secure bond between body and implanted valve that is not dependent on the continued integrity of the sutures used for insertion.
Yet another object of the invention is to provide a form of valve whereby one size fits more than one size of patient heart, and which has the parts to be stitched to the heart marked to indicate the correct placement of sutures for a particular heart size.
A still further object is to provide a combined sizing and suture placement guiding device which indicates the correct placement of sutures to ensure optimal opening and closing of the respective valve.
According to the principal aspect of the present invention, a mitral heart valve replacement of essentially flexible bioincorporable material comprises a generally D-shaped sewing ring having an opening with at least one long straight side portion, an anterior cusp hinged contiguously from that straight side portion, a posterior cusp hinged contiguously from a shorter side portion of the opening opposite the anterior cusp, and two lateral cusps hinged contiguously one from each of the remaining side portions of the opening extending between adjacent ends of the side portions from which the anterior and posterior cusps are hinged, together with chordae of bioincorporable material extending from edge portions of the cusps for connection to the papillary muscles in the cavity of the ventricle when the sewing ring is sutured to the atrio-ventricular junction of the host or patient heart, the aggregate area of the cusps exceeding the area bounded
REFERENCES:
patent: 3656185 (1972-04-01), Carpentier
patent: 3898701 (1975-08-01), La Russa
patent: 4790844 (1988-12-01), Ovil
patent: 4960424 (1990-10-01), Grooters
Burke Elizabeth M.
Isabella David
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