Surgery – Instruments – Sutureless closure
Reexamination Certificate
1999-05-13
2001-01-16
Thaler, Michael H. (Department: 3731)
Surgery
Instruments
Sutureless closure
Reexamination Certificate
active
06174322
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to an occlusion device for the closure of a physical anomaly such as a vascular aperture or an aperture in a septum, such as patent ductus arteriosus, atrial septal defect, patent foramen ovale, or ventricular septal defect comprising an occluding body extending at least within the aperture with a center piece extending in the axial direction of said occluding body as well as wire-like, elastic fixation devices emanating from the occluding body or its center piece, the ends of said fixation devices being thickened to have a spherical or lenticular shape or provided with spherical or lenticular elements.
The human circulatory system is comprised of a cardiovascular circulation and pulmonary circulation. In the embryonic phase of the development of a human being, the two circulatory systems are joined by the ductus arteriosus. The ductus connects the aorta (systemic circulation) with the pulmonary artery (pulmonary circulation). In the normal development of an infant, this ductus closes after birth. In pathological development, the ductus may not close so that the two circulatory systems remain connected even after birth. This can reduce the life expectancy of the infant.
Closure of the ductus by means of a surgical procedure is well-known. However, this procedure is very cost-intensive and is connected with a risk for the patient.
Closure of the ductus by means of an IVALON® (polyvinyl alcohol) foam plug (Porstmann method) is also well-known. In this case, a guide rail is introduced via a femoral vein into the aorta, through the ductus into the pulmonary artery and from there through the right ventricle and the right atrium and finally to the outside again via the opposite femoral vein. The ductus plug is then pushed into the ductus where it is “jammed in place.” Owing to the high pressure differential
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between the aorta and pulmonary artery, high demands are placed on the fixation of the ductus plug within the ductus.
For that reason, relatively large plugs must be used which are compressed by about 10 times their length and are 30% larger than the diameter of the ductus. Correspondingly large sheaths are required for introduction of the plug into the femoral artery. In infants, the diameter of the vessels is small and is often not large enough for a procedure of this nature in children weighing less than 30 kg.
In an occlusion device disclosed in DD 233 303 A1, the occluding body has a single-shell, hyperboloid-like basic shape and can be comprised of metal, a metal alloy, plastic and similar materials. Wire-like fixation devices extend outside the occluding body and end in a point so that the risk of injuring vascular walls exists.
In order to implant the occlusion device, it is grasped by a holding wire extending within a safety sleeve and advanced by a catheter. Due to the shape of the occluding body and the pointed ends of the fixation devices, the possibility of withdrawing an improperly implanted occlusion device is associated with considerable danger of injury to the patient.
WO 94/09 706 discloses an occlusion device having a helical basic body from which filaments emanate which evoke clot formation
A prosthesis for the closure of an atrial or ventricular septal defect is described in DE 42 22 291 C1. The prosthesis is comprised of a center piece wich is pretensioned via an extension spring from which center piece arms emanate which are in contact with the vascular wall. U.S. Pat. No. 3,874,388 discloses an occlusion device having a basic body from the ends of which fixation devices exercising the effect of an umbrella emanate which can be brought into contact with vascular walls.
In the case of the generic occlusion device according to EP 0 698 373 A2, an injury to the vascular walls by the fixation devices is ruled out. This results in the advantage that a change of position of the occluder itself is readily possible during implantation of the occlusion device. The spherical or lenticular ends of the fixation devices also ensure that if there is a high pressure differential between the vessels joined by the ductus, the fixation elements which are normally in contact with the internal walls of the vessel cannot lead to an injury resulting from movement of the occlusion device. The spherical ends also prevent injury even if the device is possibly transported through the vessels without the protection of a catheter.
SUMMARY OF THE INVENTION
The present invention is an occlusion device of the type named above in which the fixation devices cause no reduction of lumen of the vessels in the walls of which the fixation devices are in contact. It is also to be ensured that the fixation elements do not lead to injury of septa in particular or outer cardiac walls if, for instance, a heart shrinks due to aging. Furthermore, it should be possible to directionally rotate the occlusion device without difficulty in order to bring about an optimum seat.
In accordance with the invention, the fixation device is preshaped and/or pretensioned in such a way that the fixation device is in level contact with the wall surrounding the aperture or follows its direction in the shape of a curve.
In accordance with the invention, the fixation device is preshaped or pretensioned before insertion into a catheter via which the fixation device is introduced to the aperture so that after insertion of the occlusion device, the fixation device or the leg is automatically brought into contact with the wall without perceptibly reducing the lumen of the vessel. The largely level contact with the wall itself produces the advantage of a secure fixation so that the implant does not slip out of place even with large pressure differentials between the vessels or chambers joined by the apertures.
It is particularly provided for that the fixation device is comprised of multiple legs, each of which emanates from the occluding body or the center piece, whereby each leg has a smoothly curved convex shape in relation to the occluding body. Alternatively, there is the possibility that each leg rises radially inward only to slope downwards after reaching a maximum. Other geometrical forms of the wire-like, elastic fixation device are also possible.
As a result of the fact that the fixation device undergoes a specific preshaping, the forces acting on the fixation devices brought about by the passage through the catheter are unable to bring about any such lasting deformation that the fixation devices contact the wall aperture in a non-defined manner.
The fixation devices itself is preferably comprised of shape memory nickel-titanium wires which are given a desired preferred shape by mechanical means and then subjected to heat treatment. In setting the preferred shape, the deformation caused by the passage through the catheter is taken into account.
An occlusion device in which the fixation devices are connected with the center piece extending in the axial direction of the occlusion device, said center piece having a molded part in the form of a connecting piece with an at least partially circumferential groove, in which the molded part can be grasped by guide forceps movable within a catheter during implantation of the fixation devices, is distinguished by the fact that the guide forceps surround the molded part with play at least when being pushed inside the catheter. In particular, the guide forceps engage the groove with play by means of claw-like or hook-like ends.
This measure ensures that the guide forceps with the fixation device can be guided through catheters which are not straight but rather strongly curved. The relative movement between the occlusion device and the guide forceps results in a relatively short rigid unit so that curves of the type mentioned can be passed.
In order to undertake a precise axial rotation of the fixation device so that it can be implanted in the desired positions, a further development of the invention provides for rotation of the fixation device with axial rotation of the guide forceps. For this purpose, a partially circumferent
Cardia Inc.
Kinney & Lange , P.A.
Thaler Michael H.
Trinh (Vikki) Hoa B.
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