Heart valve disease is a significant cause of morbidity and mortality, resulting from a number of ailments including rheumatic fever and birth defects. The natural heart valves are identified as the aortic, mitral (or bicuspid), tricuspid and pulmonary valves, and each has leaflets to control the directional flow of blood through the heart. Worldwide, approximately 300,000 heart valve replacement surgeries are performed annually, and about one-half of these patients receive bioprosthetic heart valve replacements, which utilize biologically derived tissues for flexible fluid-occluding leaflets.
The most successful bioprosthetic materials for flexible leaflets are whole porcine valves and separate leaflets made from bovine pericardium stitched together to form a tri-leaflet valve. However, flexible leaflets formed of polymeric, fiber-reinforced, and other synthetic materials have also been proposed. The most common flexible leaflet valve construction includes three leaflets mounted to commissure posts around a peripheral support structure with free edges that project toward an outflow direction and meet or coapt in the middle of the flowstream. A suture-permeable sewing ring around the inflow end provides a platform for anchoring sutures.
Manufacturers stabilize bioprosthetic heart valves with bracketing structure within jars filled with preserving solution for shipping and storage prior to use in the operating theater. The valves are stabilized with various structures, including a 2- or 3-piece clip and tubular sleeve structure, such as shown in U.S. Pat. No. 6,416,547 to Erickson, et al.
Prosthetic valves typically have a delivery holder centrally located and sutured thereto, and an elongated delivery handle couples to the holder for manipulating the valve assembly during implant. Because of the standard delivery direction, the holder is attached to the inflow side such as the sewing ring for mitral valves and to the outflow side such as the stent cusps or outflow commissure tips for aortic valves.
When delivering a tissue type prosthetic valve in the mitral position, the outflow commissure posts are on the leading or blind side of the valve and may become entangled with pre-installed anchoring sutures. The difficulty of delivery is compounded if the surgery is through a minimally-invasive access channel, a technique that is becoming more common. The problem of entanglement is termed “suture looping,” and means that the suture that is used to attach or mount the valve to the heart tissue is inadvertently wrapped around the inside of one or more of the leading commissure post tips. If this occurs, the looped suture may damage one of the tissue leaflets when tightly tied down, or may interfere with the valve implant procedure and prevent maximum coaptation of the valve leaflets, resulting in a deficiency in the prosthetic mitral valve, requiring an immediate explant.
Some attempts have been made to overcome these problems in current holders for prosthetic mitral valves. An example of such a holder is U.S. Pat. No. 4,865,600, Carpentier, et al., incorporated herein by reference, which provides a holder having a mechanism that tensions attachment sutures to constrict the valve commissure posts inwardly prior to implantation. Another similar device is seen in U.S. Pat. No. 6,966,925 to Stobie, also incorporated herein by reference, which includes a shaft member positioned on the holder that is axially movable just prior to valve deployment to cause lengths of the attachment sutures to extend axially beyond the commissure posts in the fashion of a tent.
Despite a number of advances, there is still a need in the art for a holder and associated packaging for tissue-type prosthetic mitral valves that helps prevent suture looping and is more intuitive in use.