Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Heart valve – Flexible leaflet
Patent
1998-11-10
2000-09-05
Milano, Michael J.
Prosthesis (i.e., artificial body members), parts thereof, or ai
Heart valve
Flexible leaflet
623 219, A61F 206
Patent
active
06113631&
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a prosthetic heart valve comprised of a support housing (stent) with a base ring which has at least two posts extending substantially in the axial direction of the ring and connected by an arcuate wall serving to fasten two flexible cusp-shaped leaflets.
BACKGROUND OF THE INVENTION
Such a construction is known for example from DE 38 34 545 C2. The support housing disclosed there is comprised of a cylindrical base ring which is extended by three posts tapering in the axial direction and offset respectively about the periphery by 120.degree.. The end wall surfaces which lie between the posts serve to receive and secure three cusps [leaflets] which ensure the closing and opening of the heart valve. In the closed state, the cusp-shaped leaflets lie against each other at their free edges with the formation of an overlapping region. This construction as well as that of the construction described in DE 42 22 610 closely resembles the natural aortic valve in which the connection line between the cusp-shaped leaflet with the natural aorta root approximates the intersection of a cylinder with the aortic vessel. In this region the connection line closes the downstream side commissures in which the lines or the cusp-shaped leaflets lie. These commissures prevent the inversion of the cusp-shaped leaflets and serve in combination with the cusp-shape leaflet overlapping regions for bracing the opposing cusp-shaped leaflets.
To reduce the high stresses in the commissure regions, i.e. in the region of the posts, these must be formed so as to be flexible especially in their upper parts. There is however the danger that because of closing pressure differences excessive deformation will arise which can finally lead to creeping and as a consequence, to premature fatigue.
OBJECT OF THE INVENTION
It is the object of the present invention to provide a prosthetic heart valve of the originally described type in which the forces arising between the cusps-shaped leaflets and the support housing are uniformly limited to the smallest possible.
SUMMARY OF THE INVENTION
These objects are attained with the prosthetic heart valve which is characterized in that the connection line of the cusp leaflet with the upper inner edge of the wall lies in a plane. The region between the posts along which the connection line runs is therefore not, as is known from the state of the art, any longer bulged three dimensionally, but rather lies in a plane whereby the connection curve is formed by the intersection of a plane inclined relative to the longitudinal axis of a cylinder with this cylinder. Because of this feature, upon opening and closing of the three cusp-shaped [leaflets], high stresses can be effectively avoided, especially in the regions of the post tips. Simultaneously it can be ensured that the transition of the cusp-shaped leaflet between its open and closed position is improved, thereby significantly increasing the functional reliability of the heart valve. The overlapping surfaces of the heart valve with three cusp-shaped leaflets can be significantly reduced by the cusp-shaped leaflet connection according to the invention so that folding of the cusp-shaped leaflet surfaces lying against one another in the closed state can be avoided.
The configuration according to the invention is useable also with two cusp-shaped leaflet heart valves as well as with the three cusp-shaped leaflet heart valve.
The walls between the posts can be configured as solid surfaces or as strips or as is described for example in DE 42 22 610 A1. The end surfaces of the wall for the cusp-shaped leaflet attachment can be beveled outwardly in the radial direction, thereby simplifying the fastening of the cusp-shaped leaflets to the respective surfaces.
Especially with heart valves having two cusp-shaped leaflets, although also with three cusp-shaped leaflet heart valves, the posts form at their free ends, a prismatic inner support for the cusp-shaped leaflets. The post end surfaces are then substantially trian
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patent: 5824062 (1998-10-01), Patke et al.
patent: 5855602 (1999-01-01), Angell
Adiam Medizintechnik GmbH & Co. KG
Dubno Herbert
Milano Michael J.
Pellegrino Brian E.
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