Transcatheter occluding implant

Details Transcatheter occluding implant Transcatheter occluding implant

1998-11-09

2001-06-12

Buiz, Michael (Department: 3731)

Surgery

Instruments

Sutureless closure

Reexamination Certificate

active

06245090

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a transcatheter occluding implant for portion of a vessel lumen. Generally speaking, these implants comprise a plug for siting in the lumen and collapsible for transfer to its position in the lumen and include means for retaining the plug in the lumen.
There are numerous circumstances when there is a requirement to occlude a vessel in the treatment of medical conditions ranging from critical care applications to cosmetic applications. This invention relates to products for use in the occlusion of vessels in the human body.
2. Background Information
Conventionally vessels are occluded using coil devices. Coils are metallic based devices and typically consist of a metal wire wound into a helical spring. This length of spring however, has the property of being able to coil up into various pre-set shapes in order to occlude the vessel. Coils are used in a whole range of applications such as arterial and venous embolization, embolization of selective vessel supply to tumours, arterio-venous malformations, embolization of aneurysms and male sterilisation. Coils are unsuitable for closure of varicose veins, varicoceles and other similar venous applications due to the high level of collateral flow in the venous circulation.
A typical example of a device consisting of a wire for occluding an aperture within a body surface such as an arterial and ventricular septal defects is described in U.S. Pat. No. 5,108,420 (Marks).
Patent Ser. No. WO 92/19162 (Seld) shows a surgical implantation device to be placed within a patient's body and seal a herneal rupture in the abdominal fascia. Essentially, this consists of a annular support large enough to cover the opening and a plug which is placed through the opening. Similarly, patent Ser. No WO 97/41778 (Gilson) discloses a transcatheter occluder device which usually has a pair of spaced-apart annular supports interconnected by a narrow neck portion extending between the annular supports. The device is formed by a highly compressible foam plastics material and by virtue of its geometry, includes an opening, the neck siting in the defect opening while the annular supports remain on opposite sides of the opening. This device depends on its physical geometry for use in occlusion of holes. It is necessary that it engages and overlaps the side wall of the occlusion and is thus anchored by engagement with a peripheral face defining the opening.
Very often, vascular vessels need to be blocked. These vessels by the very nature of their anatomy can be described as lubricious tubes providing a very slippy environment and thus stabilising an occlusive device in such a vessel lumen can be extremely difficult. A further problem associated with such vessels is that they can have an indigenous pulse within the arterial wall. Such a pulse can be transmitted along the entire length of the vessel and against any occluding implant mounted therein. Further, by the very nature of the change in pressure within the vessel, the vessel, for example, will often expand and contract and there is thus a need for an implant that will be able to accommodate the changes in the bore of the vessel lumen in which it is placed.
OBJECTS
The present invention is directed towards providing an improved construction of transcatheter occluding implant.
In particular, the invention is directed towards the provision of an occluder that can be sited in vascular vessels.
Further, the invention is directed towards providing an improved construction of occluding implant that will accommodate the expansion and contraction of vessels in which it is sited.
SUMMARY OF THE INVENTION
According to the invention, there is provided a transcatheter occluding implant for portion of a vessel lumen comprising:
a plug member;
a lumen anchoring means including portion of an outer surface of the plug member for securing the plug member in the lumen;
expansion means for causing the lumen anchoring means to bear against the interior of the lumen;
self support means for retaining the anchoring means in position; and
a resilient foam plastics material incorporated in the plug member forming at least portion of the plug member to provide the expansion means and the self supporting means.
A great advantage of using a resilient foam plastics material is that the plug member will expand and contract as required during use and thus will always accommodate, for example, pulsating flows of liquids and increases and decreases in liquid pressure, such as blood pressure.
Ideally, the portion of the outer surface forming the anchoring means provides a closed path around the plug member for total occlusion of the vessel on initial insertion and expansion. While it may not always be practical or necessary to block all the blood flow immediately, for example, where there would be an aneurysm and one would be relatively wary of rupturing the interior of the vessel lumen. In many other circumstances, it would not necessarily be a problem and obviously, where it is desired to cut off the flow, for example, of blood to a tumour, the quicker the blood flow can be stopped, the better.
Ideally, the outer surface of the plug member adjacent the interior of the lumen is of an open cell structure forming a plurality of tissue receiving orifices. The advantage of this is that as the plug member is retained in position, gradually tissue will be able to grow into the plug member so that the plug member will become a permanent fixture. For example, in many situations, it might not be desired to remove the implant, such as, for example, where it was used in the fallopian tube for the purpose of female sterilisation. Similarly, it might be extremely important when the implant was an aneurysm implant.
In a still further embodiment of the invention, all the plug member is of a foam plastics material.
Ideally, the foam plastics material is an open foam cell material. This is one of the best materials for using as it has extremely good hysteresis properties and, generally speaking, the foam plastics material should be manufactured from a polymeric material having good hysteresis properties.
Further, in accordance with the invention, the rate of expansion and compressibility of the foam material is chosen to be greater than that to which the bore of the lumen is subjected. It will be appreciated that if, for example, a vessel contracts and expands regularly, it is vital that the contraction and expansion of the implant does not cause abrasive damage to the vessel lumen.
Ideally, the surface area of the plug member in contact with the internal bore of the lumen on initial insertion exceeds the minimum area necessary to anchor the occluding implant within the lumen. While it would be possible to hold an implant in position by some fixing means, it is obviously much better that, from the start, the implant should hold itself in position.
Ideally the foam material has a pore size of less than 250 microns. Preferably the foam material has a pore size of less than 100 microns and may be within the range than 90% and in some instances greater than 94%.
One of the major advantages of the present invention is that the foam structure of the plug member is such as to confer a 3 dimensional structure to the implant. By virtue of an open cell foam construction, tissue growth can occur and following this, vascularisation of the implant. Following tissue growth, the presence of the tissue will promote the occlusion of the original implant which is now sustainable. The tissue growth occurs by virtue of the open cell nature of the foam structure. Thus, there may be situations where, for example, it is now possible, without causing damage to the vessel walls, to offer a complete barrier to the flow of liquid through the lumen on initial insertion and expansion of the implant within the lumen. However, initially the transcatheter occluding implant would block most of the flow and then, as tissue growth it promoted, the total flow will be blocked. It will be appreciated that

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