Endovascular prosthesis

Abstract

An expandable endovascular prosthesis comprising: body having a proximal end and a distal end; a first expandable portion disposed between the proximal end and the distal end, the tubular first expandable portion being expandable from a first, unexpanded state to a second, expanded state with a radially outward force thereon to urge the first expandable portion against a vascular lumen; and a second expandable portion attached to the first tubular expandable portion; the second expandable portion being expandable upon expansion of the tubular first expandable portion. The endovascular prosthesis is particularly useful in the treatment of aneurysms, particularly saccular aneurysms. Thus, the first expandable portion serves the general purpose of fixing the endovascular prosthesis in place at a target vascular lumen or body passageway in the vicinity at which the aneurysm is located and, upon expansion of the first expandable portion, the second expandable portion expands to block the aneurysmal opening thereby leading to obliteration of the aneurysm. A method of delivering and implanting the endovascular prosthesis is also described.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] In one of its aspects, the present invention relates to an endovascular prosthesis. In another of its aspects, the present invention relates to a method of treating an aneurysm in a patient. [0003] 2. Description of the Prior Art [0004] As is known in the art, an aneurysm is an abnormal bulging outward in the wall of an artery. In some cases, the bulging may be in the form of a smooth bulge outward in all directions from the artery—this is known as a “fusiform aneurysm”. In other cases, the bulging may be in the form of a sac arising from an arterial branching point or from one side of the artery—this is known as a “saccular aneurysm”. [0005] While aneurysms can occur in any artery of the body, it is usually those which occur in the brain which lead to the occurrence of a stroke. Most saccular aneurysms which occur in the brain have a neck which extends from the cerebral blood vessel and broadens into a pouch which ...

AI Technical Summary

Benefits of technology

[0034] Thus, the present inventors have discovered a novel endovascular prosthesis having the characteristic of a covering material disposed on the second expandable portion. In the unexpanded state of the prosthesis, the covering material has a surface area which is larger than the surface area of the second expandable portion over which it is disposed. This significantly facilitates expansion of the second expandable portion compared to the case where the covering material has a surface area substantially the same as that of the second expandable portion over which it is disposed. In most cases, as the second expandable portion is expanded, the surface area thereof will increase to be equal to or greater than the surface area of the covering material in the unexpanded state of the second expandable portion. In the latter case, it is therefore preferred to use a covering material which has some elasticity so that it may be stretched further beyond its original surface area in the unexpanded state of the second expandable portion.

[0036] Thus, the present inventors have discovered an improvement to the Marotta #2 endovascular prosthesis particularly when applied using a porous leaf portion such as the one illustrated in FIGS. 9-14. Specifically, the approach involves partially, pre-expanding the prosthesis thereby partially, pre-expanding the leaf portion before the cover material is applied to the leaf portion. Once the covering material has been applied to the leaf portion, the entire prosthesis is then compressed, preferably to its original configuration. This results in a cover material having a total surface area which is larger than the compressed leaf portion. Those of skill in the art will recognize that, when it is desired to deploy the endovascular prosthesis by expansion thereof, expansion of the leaf portion will be greatly facilitated by virtue of the fact that there is more surface area in the covering material compared with the leaf portion over which the covering material is disposed in the unexpanded state of the prosthesis.

[0041] The present endovascular prosthesis is believed to be particularly useful in the treatment of aneurysms such as those described hereinabove and is therefore believed to provide a significant alternative to the conventional surgical techniques described hereinabove. Additionally, it is envisaged that the present endovascular prosthesis may be used in the treatment of certain aneurysms which are diagnosed as being inoperable. The present endovascular prosthesis also is believed to provide a significant advantage of current endovascular approaches such as the Guglielmi Detachable Coil described hereinabove. Specifically, since the present endovascular prosthesis does not rely on insertion into the aneurysm of a metal packing material (e.g., platinum coil), the risk of rupturing the aneurysm is mitigated as is the risk of intra-aneurysmal rearrangement of the metal packing material and subsequent reappearance of the aneurysm.

Problems solved by technology

While aneurysms can occur in any artery of the body, it is usually those which occur in the brain which lead to the occurrence of a stroke.

Aneurysms also can cause problems which are not related to bleeding although this is less common.

Further, the aneurysm can also press against nerves (this has the potential of resulting in paralysis or abnormal sensation of one eye or of the face) or the adjacent brain (this has the potential of resulting in seizures).

Unfortunately, surgical techniques for treating these conditions are regarded as major surgery involving high risk to the patient and necessitate that the patient have strength even to have a chance to survive the procedure.

While these endovascular approaches are an advance in the art, they are disadvantageous.

Specifically, the risks of these endovascular approaches include rupturing the aneurysm during the procedure or causing a stroke due to distal embolization of the device or clot from the aneurysm.

Additionally, concern exists regarding the long term results of endovascular aneurysm obliteration using these techniques.

Specifically, there is evidence of intra-aneurysmal rearrangement of the packing material and reappearance of the aneurysm on follow-up angiography.

One particular type of brain aneurysm which has proven to be very difficult to treat, particularly using the surgical clipping or endovascular embolization techniques discussed above occurs at the distal basilar artery.

Successful treatment of this type of aneurysm is very difficult due, at least in part, to the imperative requirement that all the brainstem perforating vessels be spared during surgical clip placement.

Unfortunately, there are occasions when the size, shape and / or location of an aneurysm make both surgical clipping and endovascular embolization not possible for a particular patient.

Generally, the prognosis for such patients is not good.

On the other hand, if one attempts to increase the size of the leaf portion by cutting it from a larger diameter tube, the diameter of the prosthesis increases which can make it more difficult to navigate into the correct position and to use with conventional delivery devices.

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