Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Heart valve – Flexible leaflet
Reexamination Certificate
2000-07-17
2003-04-08
Willse, David H. (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Heart valve
Flexible leaflet
C623S002150
Reexamination Certificate
active
06544285
ABSTRACT:
TECHNICAL FIELD AND BACKGROUND OF THE INVENTION
First described by Italian anatomist Antonio Valsalva, the sinuses of Valsalva are slight dilations or bulges located in the wall of the aorta opposite three respective leaflets of the aortic valve. Designed to promote closure of the aortic valve upon termination of each cardiac contraction, the sinuses of Valsalva play a critical role in ensuring proper blood flow through the aorta.
Aortic root prostheses used in replacing diseased aortic roots are generally formed from fabric such as the polyester sold under the trademark HEMASHELD. The cylindrical tube is scalloped at one end to match the scalloped shape of each corresponding aortic valve leaflet to which the tube is to be attached. After attaching the scalloped end of the tube to the corresponding leaflets, the other end of the tube is attached to the aorta, thereby replacing the sinuses of Valsalva and a portion of the ascending aorta. Although this cylindrical tube prosthesis is in widespread use, the prosthesis has disadvantages. One significant disadvantage is that although the cylindrical shape of the tube approximates the geometry of the aorta, the shape fails to capture the geometry of the sinuses of Valsalva and of the associated sino-tubular ridge. The functions of the sinuses and sino-tubular ridge are thus sacrificed when the cylindrical tube prosthesis is used as an aortic root graft. Another disadvantage inherent in using the tube prosthesis is that when the aortic valve opens, the leaflets of the valve sometimes hit the wall of the tube graft, which can cause abrasion and ultimately failure of the leaflets. These disadvantages confirm that the sinuses of Valsalva are needed to prevent the leaflets from hitting the tube wall and to promote proper function of the aortic valve.
Since the sinuses of Valsalva play an important role both in closing the aortic valve and in reducing the stress on the leaflets, using the tube graft can compromise the physiological function and longevity of the aortic valve. Surgeons have often realized that using the tube graft is at best a compromise, and that a better graft having a geometry similar to that of the natural aortic root and the sinuses of Valsalva needs to be developed. Prototypes of new grafts have been tested in valve sparing operations, and their valve function studied in vitro in a left heart simulator. The design of the aortic root graft, or prosthesis, considered preferable at the present time has evolved from these experiments. When the aortic valve is attached to this aortic root prosthesis, the physiological function of the valve is the same as that seen in an intact, natural aortic root.
SUMMARY OF THE INVENTION
Therefore, it is an object of the invention to provide an aortic root prosthesis for being implanted into a patient during a valve sparing surgery as a replacement for the biological aortic root segment and an ascending aorta.
It is another object of the invention to provide an aortic root prosthesis which has a geometry similar to that of the natural aortic root.
It is another object of the invention to provide an aortic root prosthesis which preserves the geometry and physiological functions of a biological aortic root when the prosthesis is used in an aortic graft.
It is another object of the invention to provide an aortic root-prosthesis having a geometry that prevents abrasion and failure of the leaflets of the aortic valve by preventing the leaflets from repeatedly hitting the prosthesis wall.
It is another object of the invention to provide an aortic root prosthesis with sinuses having a geometry and design adapted to promote proper blood flow, thereby allowing smooth formation of vortices in a space behind each respective leaflet, which reduces formation of thrombus and emboli.
It is another object of the invention to provide an aortic root prosthesis which includes a leaflet-sinus assembly having a circular cross-section in the circumferential direction of each leaflet, thereby decreasing stress at each leaflet-graft junction.
These and other objects of the present invention are achieved in the preferred embodiments disclosed below by providing an aortic root prosthesis for being implanted into a patient during a valve sparing surgery as a replacement for a biological aortic root segment of an ascending aorta. The aortic root prosthesis includes a hollow, annular tube having proximal and distal ends and an inner and outer wall, wherein the distal end is attached to the ascending aorta. The prosthesis also includes a plurality of sinuses circumferentially connected to the-proximal end of the tube. Each of the sinuses is adapted for being attached to an aortic wall and includes contouring means for importing a convex contour to an outer wall of the sinus, thereby creating a space between the open leaflet and its respective sinus to prevent impact between the leaflet of the valve and the inner wall of the sinus as the leaflet of the valve opens.
Preferably, the annular tube and the sinuses are comprised of a polyester fabric.
According to one preferred embodiment of the invention, a plurality of Z folds are formed in and extend circumferentially around the tube.
According to another preferred embodiment of the invention, a plurality of Z folds are formed in and extend along the vertical axis of each sinus and parallel to the longitudinal axis of the tube, thereby allowing each sinus to be stretched laterally.
According to yet another preferred embodiment of the invention, the contouring means comprises at least one purse string stitched around each sinus to form two concentric loops. The loops are gathered to form a tear-drop shape, thereby deflecting the convex contour downwardly toward a free end of the sinus remote from the tube.
The purse string preferably comprises 4-0 polypropylene suture.
According to yet another preferred embodiment of the invention, at least one of the loops is stitched approximately two millimeters from the periphery of each sinus.
According to yet another preferred embodiment of the invention, the proximal end of the tube is scalloped around the edge of the proximal end at a depth of at least two millimeters, thereby permitting formation of a sino-tubular junction where each sinus connects with the proximal end of the tube along the edge.
According to yet another preferred embodiment of the invention, each sinus is connected to the proximal end of the tube by respective sino-tubular junctions spaced at equal intercommissural distances.
According to yet another preferred embodiment of the invention, each sinus is connected to the proximal end of the tube by respective sino-tubular junctions. Each of the sino-tubular junctions is spaced at respective intercommissural distances from each other, whereby a first intercommissural distance is smaller than second and third intercommissural distances.
According to yet another preferred embodiment of the invention, each sinus is connected to the proximal end of the tube by respective sino-tubular junctions. Each of the sino-tubular junctions is spaced at respective intercommissural distances, whereby a first intercommissural distance is larger than second and third intercommissural distances.
According to yet another preferred embodiment of the invention, the valve is a stentless bioprosthetic valve.
According to yet another preferred embodiment of the invention, the valve is a stented bioprosthetic valve.
According to yet another preferred embodiment of the invention, a method for replacing a biological aortic root segment of an ascending aorta in a patient during a valve sparing surgery is provided, which includes providing an aortic root valve prosthesis comprising a cylindrical fabric tube having proximal.and distal ends, wherein the distal end is adapted for attachment to the ascending aorta. A plurality of sinuses are circumferentially connected to the proximal end of the tube. Each sinus is adapted for being attached to an aortic wall. Each of the sinuses is also contoured, thereby imparting a convex contour to an outer wa
Robicsek Francis
Thubrikar Mano J.
Heinemen Medical Research, Inc.
Jackson Suzette J.
Willse David H.
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