WO2002055125A2

WO2002055125A2 - Implantable composite device and corresponding method for deflecting embolic material in blood flowing at an arterial bifurcation

Info

Publication number: WO2002055125A2
Application number: PCT/IL2002/000024
Authority: WO
Inventors: Nitzan Zafrir-Pachter; Ygael Grad; Abraham Rapaport; Boaz Nishri
Original assignee: Mindguard Ltd; Nitzan Zafrir-Pachter; Ygael Grad; Abraham Rapaport; Boaz Nishri
Priority date: 2001-01-11
Filing date: 2002-01-11
Publication date: 2002-07-18
Also published as: IL140871A0; WO2002055125A3; EP1399214A2

Abstract

Implantable composite device and corresponding method for deflecting embolic material (60) in blood (80) flowing at an arterial bifurcation (52), featuring a deflecting and filtering element (27), and, a separate basis element (20) for supporting the deflecting and filtering element and for anchoring the device at the arterial bifurcation, whereby an operative composite of the deflecting and filtering element and the basis element forms the composite device having a contracted state with a first diameter and an expanded state having a second diameter greater than the first diameter, wherein the deflecting and filtering element (27) deflects the embolic material in the blood flowing toward a first branch (40) of the arterial bifurcation into a second branch (42) of the arterial bifurcation, while filtering the blood flowing toward the first branch of the arterial bifurcation. Deflecting and filtering element (27) is of finely meshed material, for effectively deflecting and filtering.

Description

IMPLANTABLE COMPOSITE DEVICE AND CORRESPONDING METHOD FOR
DEFLECTING EMBOLIC MATERIAL IN BLOOD FLOWING AT AN ARTERIAL
BIFURCATION
FIELD AND BACKGROUND OF THE INVENTION
The present invention relates to implantable medical devices for deflecting embolic material in blood flowing through arteries, and, more particularly, to an implantable composite device and corresponding method for deflecting embolic material in blood flowing at an arterial bifurcation.

The implantable composite device, herein, also referred to as the deflecting device, featuring a unique expandable dual diameter composite structure of an expandable basis element, and, a deflecting and filtering element, supported and anchored by the basis element, for deflecting the embolic material while filtering the blood flowing at the arterial bifurcation, reduces the risk of embolic material entering the internal carotid artery of a subject, and, reduces the risk of blood clots occurring in the subject. Herein, embolic material and blood clots are collectively and interchangeably referred to as'embolic material'.

A major portion of blood supplied to the brain hemispheres is by two major arteries in the neck, referred to as common carotid arteries (CCA), each of which branches off, or bifurcates, into an internal carotid artery (ICA), and, into an external carotid artery (ECA).

Blood to the brain stem is supplied by two vertebral arteries.

Stroke is a leading cause of disability, death, and health care expenditure. It is the second most common cause of death worldwide, exceeded only by heart disease, and is the third most common cause of death in the U. S., as described in Heart And Stroke Statistical
Update, Dallas, Tex., USA, American Heart Association, 2000.

Stroke is caused either by ischemia-infarction or-intracranial hemorrhage.

Infarction constitutes 85 to 90 percent of the total group in western countries, as described by Sacco, R. L., Toni, D., and, Mohr, J. P., in Classification Of Ischemic Stroke, Stroke:
Pathophysiology, Diagnosis And Management, editors: Barnett, H. J. M., Mohr, J. P., Stein,
B. M., and, Yatsu, F. M., third edition, Churchill Livingstone, N. Y., USA, 1998,271-83.

The pathogenesis of ischemic stroke is complex with multiple potential mechanisms. The carotid plaque is only one source of stroke, accounting for no more than 15-20 % of cases, as described by Petty, G. W., Brown, Jr., R. D., Whisnant, J. P., Sicks, J. D., O'Fallon, W. M., and, Wiebers, D. O., in Ischerzic Stroke Subtypes, A Population-based Study Of Incidence
And Risk Factors, Stroke, 1999,30,2513-16. More frequently, infarcts are caused by more proximal sources of emboli, that is, the heart and the aortic arch. The commonest causes of cardioembolic stroke are nonrheumatic (often called nonvalvular) atrial fibrillation, prosthetic valves, rheumatic heart disease (RHD), congestive heart failure, and ischemic cardiomyopathy.

A recent population based study from Rochester, Minn., USA, found that the main identifiable subtype of ischemic stroke was cardioembolic with nearly 30 % of cases, while all large vessel cervical and intracranial atherosclerosis with stenosis altogether constituted about 16 %, as described by Petty et al., ibid. Further, often multiple mechanisms coexist, as described by Caplan, L. R., in Multiple Potential Risks For Stroke, JAMA 2000,283, 1479-80. Wilson, R. G. and Jamieson, D. G., in Coexistence Of Cardiac And Aortic Sources Of Embolization And High-grade Stenosis And Occlusion Of The Internal Carotid Artery,
J. Stroke Cerebrovasc Dis., 2000,9,27-30, reviewed the experience of Petty et al. with patients who had high grade internal carotid artery stenosis or occlusion, and also had cardiac and aortic evaluation.

Potential cardiac or aortic sources of emboli were present in 54 % of patients; aortic arch plaques greater than 4 mm in diameter were found in 26 % of patients with severe internal carotid artery occlusive disease.

Prevention is clearly the most cost-effective approach to decreasing the burden of stroke. Available strategies to prevent stroke include medical treatment, surgery (carotid endarterectomy), and carotid stenting.

Current medical treatments include antiplatelet drugs, such as aspirin, ticlopidine, clopidogrel, and dipyridamol, for presumed athreothrombotic origin. These treatments reduce the risk for recurrent ischemic event by no more than 15-20 %. Anticoagulants, such as Warfarin for non valvular atrial fibrillation, reduce the risk by 60 %, however, even in carefully conducted and monitored clinical trials, a substantial number of patients stopped anticoagulation, as described by Hart, R. G., Benavente, O., McBride, R., and,
Pearce, L. A., in Antithrombotic Therapy To Prevent Stroke In Patients With Atrial
Fibrillation : A Affieta-analysis, Ann Intern Med., 1999,131,492-501.

Carotid endarterectomy was shown to be beneficial in selected cases of medium grade symptomatic, and also in asymptomatic carotid stenosis, by greater than 60 %, whenever complication rates are kept low, as described by Chassin, M. R., in Appropriate Use Of Carotid Endarterecto7ny (editorial), N. Engl. J. Med., 12998,339,1468-71.

Nevertheless, a high proportion of recurrent stroke was not related to the large artery atherothrombotic disease, but to other causes including cardioembolism, as recently reported by the NASCET (North American Symptomatic Endarterectomy Trial) investigators, Barnett, H. J. M., Gunton, R. W., Eliasziw, M., et al., in Causes And Severity Of Ischemic Stroke In Patients With Internal Carotid Artery Stenosis, JAMA, 2000,283, 1429-36. In fact, strokes related to cardioembolism tended to be more severe. The population of patients with carotid stenosis in'real life'often includes patients with severe cardiac disease, concomitant protruding aortic arch atheroma, atrial fibrillation, or congestive heart failure. The proportion of patients with such concomitant disease increases substantially in an elderly population.

Thus, the risk of recurrent cardioembolic stroke, even in patients operated for carotid stenosis, is estimated to be substantially higher, as described by Barnett, H. J. M., et al., ibid.

Carotid artery stenting has potential advantages of offering treatment to high risk patients with carotid stenosis, lowering peri-procedural risk, decreasing costs, and reducing patient inconvenience and discomfort. Preliminary results from clinical trials comparing carotid stenting to carotid endarterectomy have shown similar results, as described in
Major Ongoing Stroke Trials, Stroke, 2000,31,557-2.

The approach to prevention of such a multi factorial complex syndrome as stroke is necessarily multifaceted. Carotid angioplasty, with stenting by itself, does not address additional sources of emboli, even after successful reduction of local stenosis. More efficient endovascular approaches to stroke prevention needs to take into account this complexity in cerebrovascular disease. In this context, an intravascular implant that also addresses prevention of emboli from proximal sources can be a valuable addition in the arsenal of the practicing physician.

Introducing filtering means into blood vessels, particularly into veins, has been known for some time. However, filtering devices known in the art are designed for filtering blood flowing in the vena cava, and for stopping embolic material having a diameter of the order of centimeters, but, are unsuitable to deal with arterial embolic material, with which the present invention is concerned, especially in cases where the diameter of such material is typically of the order of down to microns. Furthermore, the flow of blood in the veins does not resemble arterial flow by its hemodynamic properties.

However, when considering the possible cerebral effects of even fine embolic material occluding an artery supplying blood to the brain, the consequences may cause irreversible brain damage, or, may even be fatal.

In light of the short period of time during which brain tissue can survive without blood supply, there is significant importance to providing suitable means for preventing even small sized embolic material from entering the internal carotid artery, so as to prevent brain damage, or, even death.

The size of the filaments that make up the deflecting and filtering element, and the
Porosity Index thereof, defined hereinafter, are major features of the deflecting device of the present invention, as explained herein, below. By contrast, in venous blood filters currently known in the art, no particular attention has been given to the size of the filaments. It is noted that embolic material in venous blood is made up of only blood clots, while in arterial blood, it is necessary to deal with emboli featuring different materials, such as blood clots and atherosclerotic plaque debris, etc.. Accordingly, in order to provide efficient filtering means, a blood deflecting and filtering element should be of fine mesh.

However, a fine mesh blood filter has a higher tendency toward occlusion.

It is also be noted that the flow ratio between the ICA and the ECA is about 3: 14: 1. This flow ratio indicates the significantly higher probability of embolic material flowing into the ICA rather than into the ECA. However, the ECA is a relatively non-hazardous artery because it supplies blood to superficial organs in the face and head, which are not life supporting and which receive blood supply from collateral blood vessels.

Therefore, embolic material reaching these organs does not cause substantial damage to a subject.

In two copending patent applications of the same applicant hereof, PCT/IL00/00145 and PCT/IL00/00147, the teachings of which are incorporated-by reference as if fully set forth herein, there are described implantable stroke preventing devices. Preferred embodiments of the device of the present invention feature improvements over those disclosed in the aforementioned copending patent applications, with respect to relative simplicity and reduced cost of manufacturing, and, in flexibility of internal positioning.

Manufacturing braided stents and prostheses is known in the art. For example, in the disclosures of WO 97/16133, EP 804909, EP 895761, and, WO 99/55256, the teachings of which are incorporated by reference as if fully set forth herein, there are described methods of manufacturing braided stents. Such braided stents present various advantages. However, they are all made for the purpose of preventing stenosis and for supporting blood vessels. The relatively large mesh sizes employed, and, the thickness and shape of the stent struts, make them unsuitable for use as a deflecting and filtering element for deflecting embolic material.

There is thus a need for, and it would be highly advantageous to have an implantable composite device (deflecting device) and corresponding method for deflecting embolic material in blood flowing at an arterial bifurcation, thereby reducing the risk of embolic material entering the internal carotid artery of a subject, and, reducing the risk of blood clots occurring in the subject.

SUMMARY OF THE INVENTION
The present invention relates to an implantable composite device and corresponding method for deflecting embolic material in blood flowing at an arterial bifurcation. The implantable composite device, referred to as the deflecting device, featuring a unique expandable dual diameter composite structure of an expandable basis element, and, a deflecting and filtering element, supported and anchored by the basis element, for deflecting the embolic material while filtering the blood flowing at the arterial bifurcation, reduces the risk of embolic material entering the internal carotid artery of a subject, and, reduces the risk of blood clots occurring in the subject.

It is thus an object of the present invention to provide an implantable composite device for deflecting embolic material in blood flowing at an arterial bifurcation, which is suitable for positioning within a blood vessel supplying blood to the brain, and further suitable to deflect embolic material that would have flowed into the internal carotid artery, to flow into the external carotid artery, thereby preventing entry of the embolic material into the internal carotid artery, thus, preventing extracranial embolus to occlude small intercranial arteries in the brain.

It is another object of the present invention to provide a method for treating a subject suffering from embolic disease or another condition associated with embolic material, or, aneurysms, by selectively occluding passage of embolic material into the internal carotid artery. It is another object of the invention to provide a method for preventing conditions associated with embolic material. It is another object of the present invention to provide a method of manufacturing the deflecting device of the present invention. Other objects of the invention are apparent throughout the following description.

The implantable composite device, or, deflecting device, of the present invention, featuring an expandable dual diameter composite structure of an expandable basis element, and, a deflecting and filtering element, supported and anchored by the basis element, for deflecting the embolic material while filtering the blood flowing at the arterial bifurcation, functions as an intravascular carotid artery stent-like device, designed especially to prevent anterior circulation strokes occurring due to proximal sources of embolic material.

In a first aspect of the present invention, the implantable composite device is positioned in the vicinity of an arterial bifurcation for causing embolic material in blood flowing toward a first branch of the bifurcation to be deflected into a second branch of the same bifurcation, by way of a deflecting and filtering element, suitable to deflect the embolic material to the blood flowing toward the second branch, while filtering the blood flowing toward the first branch. In this embodiment, the deflecting device features an expandable dual diameter composite structure having a contracted state with a first diameter, and, an expanded state having a second diameter greater than the first diameter.

According to a preferred embodiment of the present invention, the implantable composite device is designed for positioning in the vicinity of a bifurcation of an artery leading to, or located in, the common carotid artery (CCA) on the one hand, and leading to a non-vital artery on the other hand, featuring a deflecting and filtering element suitable to deflect the embolic material in blood flowing toward the CCA, into the non-vital artery, while filtering blood flowing toward the CCA. In this embodiment, the deflecting device features an expandable dual diameter composite structure having a contracted state with a first diameter, and, an expanded state having a second diameter greater than the first diameter.

In a preferred embodiment of the deflecting device according to the present invention, the deflecting and filtering element has openings, preferably, in a range of between about 100 urn to about 700, um, and, more preferably, in a range of between about 100 pm to about 400 um. In an open or expanded state, the deflecting device has a diameter, preferably, in a range of between about 5 mm to about 35 mm, and, more preferably, in a range of between about 5 mm to about 30 mm, and, in a closed or contracted state, a diameter, preferably, in a range of between about 1 mm to about 4 mm, and, more preferably, in a range of between about 1 mm to about 3 mm.

Different geometrical shapes, configurations, and, sizes, of wires can be used for constructing the deflecting device and elements thereof. According to a preferred embodiment of the present invention, the wires constituting the basis element of the deflecting device have a cylindrical configuration with a circular cross-section diameter, preferably, in a range of between about 100 llm to about 1500 um, and, more preferably, in a range of between about 100 um to about 200 um, while the wires of the deflecting and filtering element have a diameter, preferably, in a range of between about 20 um to about 75 u. m, and, more preferably, in a range of between about 20 um to about 40 um.

According to other embodiments of the present invention, the cross-section of the wires can have other geometrical shapes and configurations, for example, elliptical, square, or, rectangular.

The deflecting device of the invention can be made of any suitable material. For instance, the filaments can be made of a material selected from among 316L stainless steel, superelastic Nitinol, Elgiloy, and mixtures of different metals and alloys.

In another aspect, the present invention includes a method for preventing embolic material flowing in blood toward a first branch of an arterial bifurcation from entering into the first branch, comprising implanting upstream to the bifurcation a deflecting and filtering element suitable to deflect the embolic material flowing in the blood to a second branch. The deflecting device features an expandable dual diameter composite structure having a contracted state with a first diameter, and, an expanded state having a second diameter greater than the first diameter.

According to a preferred embodiment of the present invention, the method is for preventing the embolic material in blood flowing in the CCA from accessing the ICA, comprising implanting in the vicinity of a bifurcation of an artery leading to, or located in, the common carotid artery (CCA) on the one hand, and leading to a non-vital artery on the other hand, a deflecting and filtering element suitable to deflect the embolic material in the blood flowing toward the CCA, into the non-vital artery, while filtering the blood flowing toward the CCA.

According to a preferred embodiment of the present invention, the deflecting and filtering element is implanted in the vicinity of the bifurcation of the common carotid artery (CCA) into the internal carotid artery (ICA) and the external carotid artery (ECA).

The present invention further includes a method for preventing cerebralvascular diseases or their recurrence, comprising implanting in the vicinity of a bifurcation of an artery leading to, or located in, the common carotid artery (CCA) on the one hand, and leading to a non-vital artery on the other hand, a deflecting and filtering element suitable to deflect embolic material in blood flowing toward the CCA, into the non-vital artery, while filtering the blood flowing toward the CCA, the deflecting device featuring an expandable dual diameter composite structure having a contracted state with a first diameter, and, an expanded state having a second diameter greater than the first diameter.

In one particular embodiment, the deflecting and filtering element is implanted in the vicinity of the bifurcation of the common carotid artery (CCA) into the internal carotid artery (ICA) and the external carotid artery (ECA).

For instance, the deflecting and filtering element can be positioned in the carotid bifurcation, its proximal end in the common carotid artery (CCA) and the distal end in the external carotid artery, thus, functioning by filtering blood at the ICA orifice and by deflecting embolic material particles to the external carotid artery (ECA) territory. Another possible location is the brachiocephalic bifurcation, deflecting embolic material particles to the right subclavian artery (the right hand), for preventing access to the right CCA.

The deflecting device may be combined with a conventional stent, for example, for the treatment of bifurcation lesions, where a stent is positioned in the side branch and the deflecting device in the main branch, wherein the conventional stent is deployed at the internal carotid artery and addresses local stenosis. The insertion and deployment techniques are similar to those employed in connection with a conventional stent. Bilateral procedures can be performed during the same session without increased risk, thus enabling deployment of bilateral carotid divertors. Moreover, the deflecting and filtering element of the deflecting device is similarly effective in deflecting embolic material above a certain size, irrespective of the composition of the embolic material.

Given that embolic matter may be composed of thrombotic material, platelet-fibrin particles, cholesterol, atheroma, or, calcified particles, such a mechanical diversion or deflection has an inherent advantage of being general to any embolic composition.

In a further aspect, the present invention is directed to the prevention of the occurrence, or, the recurrence, of cerebralvascular diseases, particularly of stroke, comprising preventing embolic material in blood flowing in the CCA from accessing the
ICA, by deflecting the embolic material into blood flowing into the ECA. Prevention of the cerebralvascular disease is achieved by implanting, permanently, in the vicinity of the bifurcation of the common carotid artery (CCA) into the internal carotid artery (ICA) and the external carotid artery (ECA), a deflecting device including an integral part, such as a deflecting and filtering element, according to the present invention.

It is emphasized, that while throughout this specification particular reference is made to the bifurcation of the CCA into the ICA, this is done for the sake of brevity only, whereby the invention is in no way limited to this specific location. The invention can be advantageously implemented at any other suitable bifurcation of blood vessels as existing, for instance, in the leg.

Thus, according to the present invention, there is provided an implantable composite device for deflecting embolic material in blood flowing at an arterial bifurcation, comprising: (a) a deflecting and filtering element; and (b) an expandable basis element for supporting the deflecting and filtering element and for anchoring the device at the arterial bifurcation, the basis element is separate from the deflecting and filtering element, whereby an operative composite of the deflecting and filtering element and the basis element forms the implantable composite device having a contracted state with a first diameter and an expanded state having a second diameter greater than the first diameter,

wherein the deflecting and filtering element deflects the embolic material in the blood flowing toward a first branch of the arterial bifurcation into a second branch of the arterial bifurcation, while filtering the blood flowing toward the first branch of the arterial bifurcation.

According to another aspect of the present invention, there is provided a method for deflecting embolic material in blood flowing at an arterial bifurcation, comprising the steps of : (a) providing an implantable composite device featuring (i) a deflecting and filtering element, and, (ii) an expandable basis element for supporting the deflecting and filtering element and for anchoring the composite device at the arterial bifurcation, the basis element is separate from the deflecting and filtering element, whereby an operative composite of the deflecting and filtering element and the basis element forms the implantable composite device having a contracted state with a first diameter and an expanded state having a second diameter greater than the first diameter,

wherein the deflecting and filtering element deflects the embolic material in the blood flowing toward a first branch of the arterial bifurcation into a second branch of the arterial bifurcation, while filtering the blood flowing toward the first branch of the arterial bifurcation; and (b) implanting and deploying in a vicinity of the arterial bifurcation the implantable composite device.

According to another aspect of the present invention, there is provided a use of an implantable composite device in the manufacture of a medical device for deflecting embolic material in blood flowing at an arterial bifurcation, for preventing the occurrence of a condition associated with the embolic material in a subject, comprising implanting and deploying the implantable composite device at an arterial bifurcation of the subject, the implantable composite device comprising:

(a) a deflecting and filtering element; and (b) an expandable basis element for supporting the deflecting and filtering element and for anchoring the device at the arterial bifurcation, the basis element is separate from the deflecting and filtering element, whereby an operative composite of the deflecting and filtering element and the basis element forms the implantable composite device having a contracted state with a first diameter and an expanded state having a second diameter greater than the first diameter, wherein the deflecting and filtering element deflects the embolic material in the blood flowing toward a first branch of the arterial bifurcation into a second branch of the arterial bifurcation, while filtering the blood flowing toward the first branch of the arterial bifurcation.

According to another aspect of the present invention, there is provided a use of an implantable composite device in the manufacture of a medical device for deflecting embolic material in blood flowing at an arterial bifurcation, for treating a subject with a condition associated with the embolic material, comprising implanting and deploying the implantable composite device at an arterial bifurcation of the subject, the implantable composite device comprising:

According to another aspect of the present invention, there is provided a method for deflecting embolic material in blood flowing at an arterial bifurcation, for preventing the occurrence of a condition associated with the embolic material in a subject, comprising the steps of :

(a) providing an implantable integral device featuring an expandable dual diameter coil element having a contracted state with a first diameter in which there is at least partial overlap of two opposing ends of the coil element, and an expanded state having a second diameter greater than the first diameter, wherein a portion of and integral with the coil element deflects the embolic material in the blood flowing toward a first branch of the arterial bifurcation into a second branch of the arterial bifurcation, while filtering the blood flowing toward the first branch of the arterial bifurcation ; and (b) implanting and deploying in a vicinity of the arterial bifurcation of the subject the implantable composite device.

According to another aspect of the present invention, there is provided a method for deflecting embolic material in blood flowing at an arterial bifurcation, for treating the occurrence of a condition associated with the embolic material in a subject, comprising the steps of : (a) providing an implantable integral device featuring an expandable dual diameter coil element having a contracted state with a first diameter in which there is at least partial overlap of two opposing ends of the coil element, and an expanded state having a second diameter greater than the first diameter, wherein a portion of and integral with the coil element deflects the embolic material in the blood flowing toward a first branch of the arterial bifurcation into a second branch of the arterial bifurcation, while filtering the blood flowing toward the first branch of the arterial bifurcation;

and (b) implanting and deploying in a vicinity of the arterial bifurcation of the subject the implantable composite device.

The present invention successfully overcomes shortcomings and limitations of presently known stent, blood filtering, and, embolic material diverting, devices and techniques, for preventing stroke due to entry of embolic material into the internal carotid artery of a subject. The above, and other, characteristics, features, and, advantages, of the present invention, are better understood through the following illustrative and non-limiting detailed description of preferred embodiments thereof.

BRIEF DESCRIPTION OF THE DRAWINGS
The invention is herein described, by way of example only, with reference to the accompanying drawings. With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice.

In the drawings :
Fig. 1A is a perspective view of a basis element for a deflecting device, in accordance with the present invention;
Fig. 1B is a deflecting device similar to that of Fig. 1A, in accordance with the present invention;
Fig. 2A is a deflecting device similar to that of Fig. 1A, in which the supporting portion for the deflecting and filtering element has been removed, in accordance with the present invention;
Fig. 2B is a deflecting device similar to that of Fig. 1B, in which the supporting portion for the deflecting and filtering element has been removed, in accordance with the present invention;
Fig. 3A is a perspective view of a basis element for a deflecting device in accordance with another preferred embodiment of the present invention ;

Fig. 3B is an illustration of a grid structure used to produce the deflecting device of
Fig. 3A, in accordance with the present invention;
Figs. 4A, 4B, and 4C are cross-sections of the deflecting device of Fig. 3A along the A-A plane and illustrate the insertion and positioning of the device according to a preferred embodiment of the present invention:

Fig. 4A schematically shows the deflecting device of Fig. 3A in collapsed form prior to expansion;
Fig. 4B shows the deflecting device of Fig. 3A in an expanded form in a first operative position;
Fig. 4C shows the deflecting device of Fig. 3A in an expanded form in a second operative position;
Figs. 5A and 5B are schematic illustration of two deflecting and filtering elements, according to two alternative preferred embodiments of the present invention:
Fig. 5A shows a sheet-like deflecting and filtering element;
Fig. 5B a tubular deflecting and filtering element;
Fig. 6A is a schematic illustration of the deflecting and filtering element of Fig. SA, coupled to a basis element of Fig. 1A or 2A or 3A, in accordance with the present invention;

Fig. 6B is a schematic illustration of the deflecting and filtering element of Fig. 5A, coupled to a basis element of Fig. 1B or 2B;
Figs. 7A, 7B, and 7C illustrate a method of folding the deflecting device when inserting it into the artery, in accordance with the present invention:
Fig. 7A shows a cross section of the deflecting device in its collapsed form;
Fig. 7B shows a cross section of the deflecting device in a partially expanded state;
Fig. 7C shows a cross section of the deflecting device in its fully expanded form;
Figs. 8A, 8B, and 8C illustrate the introduction of the deflecting device and its deployment within the artery:
Fig. 8A shows the deflecting device in its collapsed state;
Fig. 8B shows the deflecting device in a partially expanded state;
Fig 8C shows the deflecting device in its expanded state;

Fig. 9A schematically illustrates the deflecting device-of Fig. 6A, located in the bifurcation zone of the carotid artery;
Fig. 9B schematically illustrates the deflecting device of Fig. 6B located in the bifurcation zone of the carotid artery;
Fig. 10 is a cross section showing a deflecting device composed of a basis element of Fig. 3A and a deflecting and filtering element of Fig. 5B located in the bifurcation zone of the carotid artery;
Figs. 1 lA and 11B show how the deflecting devices of the invention can be used in the treatment of aneurysms ;
Fig. 11A shows a deflecting device of Fig. 6A at the site of an aneurysm; and
Fig. I I B shows the deflecting device of Fig. 6B at the site of an aneurysm of another type.

DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention relates to an implantable composite device and corresponding method for deflecting embolic material in blood flowing at an arterial bifurcation. The implantable composite device, herein, referred to as the deflecting device, featuring a unique expandable dual diameter composite structure of an expandable basis element, and, a deflecting and filtering element, supported and anchored by the basis element, for deflecting the embolic material while filtering the blood flowing at the arterial bifurcation, reduces the risk of embolic material entering the internal carotid artery of a subject, and, reduces the risk of blood clots occurring in the subject. Herein, embolic material and blood clots are collectively and interchangeably referred to as'embolic material'.

The unique dual diameter composite structure of the implantable composite device of the present invention has a contracted state with a first diameter, and, an expanded state having a second diameter greater than the first diameter.

It is to be understood that the invention is not limited in its application to the details of construction, arrangement, and, composition, of the components and elements of the implantable expandable stroke preventing device, or, to the details of the order or sequence of steps of operation or implementation of the method of manufacturing thereof, set forth in the following description, drawings, or examples. For example, the following description refers to preferred geometrical shapes, configurations, and, sizes, of the implantable composite device, and, elements and components thereof, such as the expandable basis element, and, the deflecting and filtering element, in order to illustrate implementation of the present invention.

In particular, for example, the deflecting and filtering element may be of different sizes, shapes, and, patterns, depending on specific flow parameters and/or requirements of a subject. Accordingly, the invention is capable of other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting.

The implantable composite device and corresponding method for deflecting embolic material in blood flowing at an arterial bifurcation, of the present invention, are herein disclosed for the first time, and are neither anticipated or obviously derived from the disclosures, PCT/IL00/00145 and PCT/IL00/00147, of the same applicant hereof.

The implantable composite device and corresponding method for deflecting embolic material in blood flowing at an arterial bifurcation, according to the present invention, are better understood with reference to the following description and accompanying drawings. Throughout the following description and accompanying drawings, like reference numbers refer to like elements.

The implantable composite device, or, deflecting device, of the invention, is composed of two separate (principle) elements: (a) a basis element, and, (b) a deflecting and filtering element. Each of these elements can be produced in several forms (illustrative and non-limitative examples of which follow) and than interchangeably assembled to make the composite deflecting device.

A basis element for a deflecting device in accordance with a preferred embodiment of the present invention, generally designated 20, is shown in
Fig. 1A. The basis element of the deflecting device is made of fine wire manufactured into a net-like device having a construction suitable for expanding from a contracted position in which it is deployed through the vasculator of an individual, and expanded by means well known in the art, for example, by a balloon device coupled with a catheter. Alternatively, the basis element of the device can be self-expandable, as is customary in the art with respect to peripheral stents. These techniques are well known to the skilled person, and are therefore not discussed herein in detail, for the sake of brevity.

The basis element of the deflecting device 20 has an essentially cylindrical shape with its body 22 generally serving as an anchoring portion. An anchoring portion is a portion of the device that firmly contacts the walls of the artery. Such contact causes a proliferation of cells of the wall of the artery into the net of the device, and strongly anchors it to the artery thus preventing its accidental displacement. The physiological processes leading to such anchoring are well known in the art, and will therefore not be discussed herein in detail, for the sake of brevity. The net that makes up the anchoring portion 22 of the basis element of the device can be of a large mesh, since it has no obstructing or filtering purposes.

A supporting portion 24 is provided, in this particular preferred embodiment of the present invention, to support the deflecting and filtering element, as will be discussed hereinafter. It is constructed by a plurality of wires 26, parallel extending along the longitudinal axis of the device. The supporting portion 24 is integral with or attached to the anchoring portion 22.

The size and shape of the basis element composited with the deflecting and filtering element is adjusted to match the inlet of the internal carotid artery as will be further explained hereinafter.

The embodiment of Fig. 1B is similar to that of Fig. 1A. However, the basis element of the deflecting device 20, which is essentially cylindrical, comprises a supporting portion 24 which is not limited to a part of the circumference of the device, as is the supporting portion 24 of Fig. 1A, but rather covers the whole circumference of the device.

This arrangement, of course, is easier to use, inasmuch as, as will become apparent hereinafter, there is no need to exactly match the limited area of the deflecting portion with the opening of the ICA. Furthermore, two markers 31 (which in the particular embodiment of Fig. 1B are circular in shape) are provided, which are radio opaque and serve to aid a physician in the proper positioning of the device within the artery. The markers are visible under radiographic equipment. Other markers can also be provided, as will be apparent to the skilled person, such as gold points which may be used to position the device also with respect of its rotation around its axis or the beads 28 shown in Figs. 1A and 1B, 2A and 2B, 3A and 3B, 6A and 6B, and 8A, 8B, and, 8C.

In the case of devices of the type shown in
Figs. 1A, 2A, and 3A, the markers must be attached to the device in such a position that the center of the deflecting area can be accurately located.

The structure of the anchoring portion 29 and of the supporting portion 24 is essentially similar to the structure illustrated with reference to Fig. 1A.

Looking now at Fig. 2A, a device similar to that schematically shown in Fig. 1A is shown. This device differs from that of Fig. 1A in that the supporting portion 24 thereof has been omitted, leaving a gap indicated at 30. Similarly, the device of Fig. 2B differs from that of Fig. 1B in that the supporting portion 24 of Fig. 1B has been omitted, leaving a gap indicated at 30. Two or more supporting rods 32 can be provided in this particular embodiment of the invention, to keep both ends of device 20 connected. The omission of the supporting portion is possible inasmuch as the deflecting and filtering element will be superimposed to the body of the basis of the deflecting device, and will thus be supported by it.

A further preferred embodiment of the device of the invention is shown in Fig. 3A.

This particular embodiment utilizes a coiled base element to which the deflecting and filtering element is attached. The device of Fig. 3A is constructed from the grid structure shown in Fig. 3B. This grid has an outer essentially rigid frame 30 with a meshed structure 21 attached. The size of this meshed structure and its mesh dimension are not important.

They may be of any suitable type, shape, and size (for example, as used in conventional coronary stents) as long as they allow the device to function in its dual role as anchoring portion and support portion for the filtering element.

One area of the meshed structure 21 is an open zone 27, which will be covered with a deflecting filtering element as described below.

In another preferred embodiment of the invention, the filaments of 21 that lie within zone 27 are removed resulting in an open zone (this is the embodiment that is shown in
Figs. 3A and 3B). This zone 27 is the region which, when the device is coiled and introduced into the artery, is positioned in front of inlet 54 of junction 52 leading to artery 40 (Figs. 9A and 9B).

The actual shape and size of zone 27 is not important, as long as care is taken to dimension it such that it will cover the entire junction.

The device 20 is made of a material having an elasticity suitable for expanding from a contracted position in which it is deployed through the vasculator of an individual, and expanded by means well known in the art, as will be further explained hereinafter with reference to Figs. 8A through 8C. The device is schematically shown, in the coiled position in which it is deployed, in Figs. 4A to 4C, which depict a cross-section of Fig. 3A taken along the A-A plane. In the situation depicted in Fig. 4A, the device 20 is fully coiled, so that its total diameter is substantially smaller than that of the device in is expanded position. In this position end portions 70 and 72 do not necessarily need to be close to one another, and may be far apart, as shown in the figure.

Fig 4B is a cross-section showing how the device of Fig. 3A would look in an expanded form in a first operative position ; in the case in which the diameter of the artery is smaller than that of the fully expanded device.

Fig. 4C illustrates yet another situation, in which the diameter of the blood vessel where the deflecting device is to be positioned is greater than that of the fully expanded device. In this situation end portions 70 and 72 of device 20 do not overlap at all, and a gap 29 is formed between them. This situation is permissible, as long as the gap lies against a wall of the blood vessel. This further illustrates the flexibility of the device of the invention, which can be used in conjunction with various blood vessel diameters, and can adjust itself to unpredictable situations during deployment.

Figs. 5A and 5B schematically illustrate two deflecting and filtering elements according to two alternative preferred embodiments of the invention. In the embodiment of
Fig. 5A a flat, sheet-like element 40, is provided, which is made of a frame 41 and of a finely meshed area 42. This is the area that will cover gaps 30 or 27 (Figs. 2A, 2B, 3A, and 3B), or support portions 24 or 21 (Figs. 1A and 1B and 3A (not shown in zone 27)).

Element 40 may be attached to the body 22 or 29 or 21 (Figs. 1A, 2A or 1B, 2B or 3A, respectively) in any suitable way, for example, by stitching it with stitches 43 to the body.

In the embodiment of Fig. 5B, deflecting and filtering element 44 is tubular in shape. Thus, the basis element of the deflecting device is inserted into the opening 45 of tubular element 44. Both the basis element and the deflecting device are collapsed on the delivery device (as is shown in Fig. 8) and then allowed to expand together, after they have been placed in the proper position in the artery. Proper contact between the deflecting device and the basis element (on the one hand) and between the basis element and the wall of the artery (on the other hand) is assured by a two step process. Firstly, the diameter of the basis is chosen, taking into account the diameter of the artery at the place at which the device will be installed.

Secondly, the wires of which element 44 is manufactured are slightly elastic, and thus, the diameter of tubular element 44 is chosen to be slightly smaller than the maximum expanded diameter of the basis in the artery, thus stretching the deflecting and filtering element over the basis element. The insertion of the basis element into the deflecting and filtering element of Fig. 5B in order to obtain the composite device of the invention is not illustrated in the figures, for the sake of brevity.

It should be obvious to the person of experience, that many different well-known methods can be employed to produce either woven or non-woven material for the deflecting/filtering elements.

Fig. 6 schematically illustrates the assembly of the deflecting device. In Fig. 6A the deflecting and filtering element 40 of Fig. 5A has been stitched on to the device of Fig. 1A or 2A or 3A so as to cover the supporting portion 24 (Fig. 1A), or the gap 30 (Fig. 2A), or the supporting portion or gap in zone 27 of Fig. 3A. Likewise, in Fig. 6B the deflecting and filtering element 40 of Fig. 5A has been at least partially stitched onto the basis in order to cover the supporting portion 24 (Fig. 1B), or the gap 30 (Fig. 2B). It can be seen by the skilled observer that, in the case shown in Fig. 6B, it is not necessary to stitch deflecting and filtering 40 to the basis element; but, merely to wrap it around.

The deflecting and filtering element will be held in place by the force of the basis element pressing against the walls of the artery. Fig. 7 illustrates a method of folding the deflecting device prior to deployment. As a non-limiting example, the case in which the deflecting element of Fig. 5A is attached to the basis of Fig. 1A to form the device of Fig. 6A will be considered. In this example, the gap in the basis is one half of its circumference. Fig. 7A shows the device in its collapsed form. Here the finely meshed area 42 of the deflecting element 40 is draped over the wires 26 that form the support area of the basis 20. As the device expands, the folds of the deflecting element are drawn outwards as shown in Fig. 7B until the deflecting element is stretched tightly over the surface of the fully expanded basis as shown in Fig. 7C.

Introduction of the device of the invention and its deployment are illustrated in Fig.

8. As will be apparent to the skilled person, using a self-expandable device is more convenient in many cases, because of the great mobility of the neck of the patient. The self-expandable device, of course, provides for a better anchoring of the device and is less likely than a balloon-expanded device to be dislodged in case of trauma.

Fig. 8A shows the device in its folded state, Fig. 8B shows it during the first stage of expansion, and, Fig. 8C shows it in fully expanded state. For purposes of illustration, the device 111 is the same device that is shown in Fig. 7. It is composed of basis element 20 of Fig. 1A and the deflecting element 40 of Fig. 5A. Figs. 7A, B, and, C, correspond to the situation shown in Figs 8A, B, and, C, respectively. Device 111 is supported on a guide wire 112, which is used to introduce and guide it to the desired location. In its folded position, device 111 is covered with a covering envelope 113, which may be made of polymeric material, which keeps it in its folded state. Envelope 113 is connected to a retraction ring 114, which can be pulled away from device 111 by means not shown in the figure and well known to the skilled person.

Looking now at Fig. 8B, when ring 114 is pulled away in the direction of the arrow, envelope 113 is pulled away with it, uncovering a portion of the device, indicated at 115. Since the envelope no longer obliges this portion 115 to remain in the folded position, and since the normal position of the device is expanded, this portion starts expanding to its natural, expanded state. This process is completed in Fig. 8C, when the envelope has been completely removed and the device is in its fully expanded position.

In the normally operative, expanded state, for example, as illustrated in Fig. 4C, radially directional elastic forces of the expandable property of expandable basis element operate to keep the basis element and therefore, the deflecting device, expanded, whereby, anchoring of the deflecting device in its location is less susceptible to undesired displacement as compared to deployment of balloon expanded stents. Following completion and positioning of the deflecting device 111, guide wire 112 is withdrawn from the subject, as in any other similar stent deployment procedure.

As will be apparent to the skilled person, the device of the invention does not necessarily need to be self-expandable, and it can be made of material that is expandable under pressure. In this case, the deployment of the device is carried out as in conventional stents, by placing the coiled device around an expandable balloon and by expanding the balloon under pressure when reaching the desired location. An expandable balloon can also be used in conjunction with a self-expandable device. In this case the balloon is used to increase the contact of the device with the inner walls of the arteries. These are conventional procedures and are, therefore, not illustrated in the figures, for the sake of brevity.

Figs. 9A and 9B include illustration of a carotid artery portion, generally designated 36, in which the common carotid artery (CCA) is designated 38, the internal carotid artery (ICA) is designated 40, and, the external carotid artery (ECA) is designated 42. Blood, generally referenced by 80, flowing throughout carotid artery portion 36 is indicated in
Figs. 9A and 9B by the space between all other designated arteries and deflecting device elements and components.

Figs. 9A and 9B show the devices of Figs. 6A and 6B, respectively, in position in the bifurcation zone of the carotid artery. Fig. 9B also illustrates a device that could be comprised of any of the basis of Figs. 1,2, or 3 inserted into the deflecting element of Fig.

5B. By using suitable imaging equipment, the assembly consisting of the deflecting device mounted on a catheter was inserted through the vasculator of an individual, into the CCA, until the deflecting device 20 was positioned within the bifurcation zone 52, with the deflecting and filtering element 27 extending opposite inlet 54 of ICA 40. In this position, the device was expanded whereby the anchoring walls of the deflecting device 20 anchor against respective inner walls of the common carotid artery 38 and the external carotid artery 42, with the deflecting and filtering element 24 extending across inlet 54 of the internal carotid artery 40. Then, the catheter was removed via the vasculator of the individual, and the deployment of the deflecting and filtering element 20 completed, as illustrated in Fig. 9A and 9B.

In this position, embolic material, which is schematically illustrated as particles flowing along flow lines 60 in Fig. 9A and 9B, flow in the common carotid artery 38, and upon meeting the deflecting and filtering element 24 they are prevented from entering the ICA 40, because their size is larger than the mesh of deflecting portion 24, and they are thus deflected into the external carotid artery 42.

Fig. 10 is a cross-section taken along the AA plane of Fig. 9B. It illustrates a composite device made up by inserting the basis (20) of Fig. 3A into the tubular shaped deflecting element (45) of Fig 5B. Despite the gap 29 that results because the diameter of the artery is greater than the diameter of the fully expanded basis, the flexibility of the device enables it to adjust to the situation and to perform its intended function as is clearly shown in Fig. 10. The devices of the invention are well suited to the treatment of aneurysms. Fig. 11A shows a typical illustrative example of how a device 200 of the invention could be placed in a body lumen 201 in order to treat an aneurysm 202. Another type of aneurysm is shown in Fig. 11B in which the various elements are indicated by the same numerals as in Fig. 1 lA.

Of course any combination of basis and deflecting elements from among the many embodiments of the device of this invention could be chosen according to the specific requirements of the case. As will be seen by the skilled person, the porosity of the deflecting element must be chosen in order to reduce the pressure on the aneurysm and will depend on the medical procedure that is carried out at the time of implanting the device. These procedures are well known to the skilled person and will not be herein described, for the sake of brevity.

The deflecting device of the present invention can be constructed in a way very similar to conventional stents. A person having ordinary skill in the art is knowledgeable of the various materials and methods suitable to make the deflecting device of the present invention. For instance, the deflecting device can be made of a material selected from the group consisting of nitinol, polymeric material, stainless steel, and, combinations thereof.

Preferably, the deflecting and filtering element of the deflecting device has openings, preferably, in a range of between about 100 um to about 700 um, and, more preferably, in a range of between about 100 um to about 400 um, in order to effectively prevent an undesirable amount of dangerous embolic material flowing in the blood, from entering the internal carotid artery in the region of an arterial bifurcation. The diameters of the expandable dual diameter deflecting device may somewhat vary, according to actual conditions associated with embolic material, of different subjects.

Preferably, the first diameter of the deflecting device in the closed position or contracted state varies, preferably, in a range of between about 1 mm to about 4 mm, and, more preferably, in a range of between about 1 mm to about 3 mm, and, the second diameter of the deflecting device in the open position or expanded state varies, preferably, in a range of between about 5 mm to about 35 mm, and, more preferably, in a range of between about 5 mm to about 30 mm.

Thickness and diameter of wire making up the basis element of the deflecting device is preferably, in a range of between about 100 um to about 1500 um, and, more preferably, in a range of between about 100 um to about 200 um, while that of wire used for constructing the deflecting and filtering element is preferably, in a range of between about 20 um to about 75 um, and, more preferably, in a range of between about 20 um to about 40 um. Of course, the entire deflecting device can also be constructed using wire of the same dimensions as that of the deflecting and filtering element, whereby there would be no difference in mesh size between the body, that is, the basis element of the deflecting device and the deflecting and filtering element, in which case,

a strengthening mechanism, for example, ribs, may be required for proper performance during normal operation for treating a subject.

The deflecting and filtering element of the deflecting device of the present invention preferably fulfills certain pre-determined conditions, several of which are described herein below. Various types of the deflecting and filtering element, featuring different geometrical shapes, configurations, sizes, and, exhibiting desirable properties, may be constructed for fulfilling the following described conditions.

When testing the deflecting device of the present invention under physiological conditions in the carotid region of a subject, namely: Reav = 200-500,
BPM (heart beats per minute) = 40-180,
Womersley = 2-7, wherein Reav is the average Reynolds number of the blood flowing at an arterial bifurcation of the carotid region, and, Womersley is the dimensionless heart beat parameter, the following conditions should preferably be met by the deflecting and filtering element, of the coil element of the deflecting device of the present invention:

(1) Reprox is, preferably, in a range of between about 0.3 to about 30, and, more preferably, in a range of between 0 and about 4, and, is also, preferably, equal to or less than 1, in accordance with creeping or Stokes'flow, and, (2) Shear Stress is in a range of between less than about 100 dyne/cm2 and greater than about 2 dyne/cm2, wherein Reprox is the Reynolds number for a single wire of which the deflecting and filtering element is made, and, the shear stress is measured at the deflecting device. As known to a person having ordinary skill in the art, the smaller Reprox is, the better the performance of the deflecting device.

However, the deflecting device may also operate at larger values of Reprox than indicated above, whereby, the present invention is by no means limited to any specific value of Rep..

The deflecting device according to the present invention is useful in a variety of cases. Some illustrative indications are listed below: (1) Embolic strokes from proximal sources. These are: - Atrial fibrillation (2.5 million in the U. S. A. in 1999); - Mechanical heart valve (225,000 procedures performed annually in the
U. S.); - Subjects at high risk for recurrent embolism for a certain period (S. B. E.); - Subjects at high risk for proximal emboli and absolute contraindications for anticoagulation; - Subjects at high risk for proximal emboli failing best medical treatment.

(2) In cases in where carotid stents are introduced to treat local stenosis, it is possible to introduce and deploy the deflecting device of the present invention during the same procedure if there are concomitant high risk proximal sources of emboli. These are, for instance : - Protruding Aortic arch atheroma (more than 1/3 of symptomatic subjects); - Severe carotid stenosis with concomitant cardiac disease; - Severe carotid stenosis in subjects undergoing heart surgery (5 % on the statistical basis of 600,000 coronary bypass surgeries).

All publications, patents and patent applications mentioned in this specification are herein incorporated in their entirety by reference into the specification, to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated herein by reference. In addition, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present invention.

While the invention has been described in conjunction with specific embodiments and examples thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.

Claims

WHAT IS CLAIMED IS: 1. An implantable composite device for deflecting embolic material in blood flowing at an arterial bifurcation, comprising: (a) a deflecting and filtering element ; and (b) an expandable basis element for supporting said deflecting and filtering element and for anchoring the device at the arterial bifurcation, said basis element is separate from said deflecting and filtering element, whereby an operative composite of said deflecting and filtering element and said basis element forms the implantable composite device having a contracted state with a first diameter and an expanded state having a second diameter greater than said first diameter, wherein said deflecting and filtering element deflects the embolic material in the blood flowing toward a first branch of the arterial bifurcation into a second branch of the arterial bifurcation,

while filtering the blood flowing toward said first branch of the arterial bifurcation.

2. The device of claim 1, whereby said basis element is of a type selected from the group consisting of self-expandable, and, non-self-expandable, at the arterial bifurcation.

3. The device of claim 1, whereby said basis element is self-expandable at the arterial bifurcation.

4. The device of claim 1, whereby said basis element is expandable under pressure supplied by a mechanism operative at the arterial bifurcation.

5. The device of claim 1, whereby said basis element is expandable under pressure supplied by a mechanism separate from and operative with said coil element, at the arterial bifurcation.

6. The device of claim 1, whereby there is at least partial overlap of opposing ends of said basis element in said expanded state.

7. The device of claim 1, whereby there is no overlap of two opposing ends of said basis element in said expanded state, whereby a gap is formed between said two opposing ends of said basis element.

8. The device of claim 1, whereby said basis element is a perforated sheet material.

9. The device of claim 8, whereby said perforated sheet material features a plurality of perforations or apertures for permitting growth of cells from arterial walls onto surface of said coil element, thereby prevent pathological damage to said arterial walls of the arterial bifurcation.

10. The device of claim 1, whereby said basis element is a meshed structure.

11. The device of claim 10, whereby perimeter of said meshed structure is surrounded by an essentially rigid frame.

12. The device of claim 10, whereby said meshed structure is made of braided material.

13. The device of claim 10, whereby said meshed structure is made of flat braided material.

14. The device of claim 10, whereby said meshed structure is made of braided material manufactured from a shaped memory alloy.

15. The device of claim 1, whereby said deflecting and filtering element is a finely meshed zone for said deflecting the embolic material in the flowing blood and for said filtering the flowing blood.

16. The device of claim 15, whereby said deflecting and filtering element replaces a substantially equivalently sized portion of said basis element.

17. The device of claim 15, whereby said deflecting and filtering element supplements a substantially equivalently sized portion of said basis element.

18. The device of claim 15, whereby open area of perforations or apertures of perforated sheet material as said basis element is significantly larger than mesh size openings of said deflecting and filtering element required for said deflecting the embolic material in the flowing blood.

19. The device of claim 15, whereby open area or mesh size of meshed structure as said basis element is significantly larger than mesh size openings of said deflecting and filtering element required for said deflecting the embolic material in the flowing blood.

20. The device of claim 1, whereby said first diameter of said basis element in said contracted state is in a range of between about 1 mm to about 4 mm.

21. The device of claim 1, whereby said second diameter of said basis element in said expanded state is in a range of between about 5 mm to about 30 mm.

22. The device of claim 1, whereby said first diameter of said basis element in said contracted state is in a range of between about 1 mm to about 4 mm, and, whereby said second diameter of said basis element in said expanded state is in a range of between about 5 mm to about 30 mm.

23. The device of claim 1, whereby said coil element is constructed from wires having cross-sections of variable geometrical shape and configuration selected from the group consisting of circular, elliptical, square, rectangular, and, combinations thereof.

24. The device of claim 1, whereby said basis element is constructed from material selected from the group consisting of stainless steel, superelastic Nitinol, Elgiloy, mixtures of different metals and alloys, polymeric material, and, combinations thereof.

25. The device of claim 1, whereby thickness and diameter of wire used for constructing said basis element are in a range of between about 100 microns to about 1500 microns.

26. The device of claim 1, whereby thickness and diameter of wire used for constructing said basis element are in a range of between about 100 microns to about 200 microns.

27. The device of claim 15, whereby said deflecting and filtering element is constructed from wires having cross-sections of variable geometrical shape and configuration selected from the group consisting of circular, elliptical, square, rectangular, and, combinations thereof.

28. The device of claim 15, whereby said deflecting and filtering element is constructed from material selected from the group consisting of stainless steel, superelastic Nitinol, ElgiloyTM, mixtures of different metals and alloys, polymeric material, and, combinations thereof.

29. The device of claim 15, whereby thickness and diameter of wire used for constructing said deflecting and filtering element are in a range of between about 20 microns to about 75 microns.

30. The device of claim 1, whereby said basis element is positioned along inner walls of an artery of the arterial bifurcation.

31. The device of claim 1, whereby, for the arterial bifurcation being the common carotid arterial bifurcation, said basis element is positioned along inner walls of external carotid artery of the common carotid arterial bifurcation.

32. The device of claim 1, whereby basis coil element is used for positioning said deflecting and filtering portion between arterial inner walls at an aperture of the arterial bifurcation.

33. The device of claim 1, whereby, for the arterial bifurcation being the common carotid arterial bifurcation, said basis element is used for positioning said deflecting and filtering portion between arterial inner walls located at aperture of inlet to internal carotid artery of the common carotid arterial bifurcation, thereby extending across and covering said aperture of said inlet to said internal carotid artery.

34. The device of claim 1, whereby said basis element supports and anchors said deflecting and filtering portion between arterial inner walls of an aperture of the arterial bifurcation.

35. The device of claim 1, whereby for the arterial bifurcation being the common carotid arterial bifurcation, said basis element supports and anchors said deflecting and filtering portion between arterial inner walls located at aperture of inlet to internal carotid artery of the common carotid arterial bifurcation, thereby extending across and covering said aperture of said inlet to said internal carotid artery.

36. The device of claim 1, whereby at least one radiographic opaque marker is located at a position on said basis element, for use in positioning said basis element within an artery at the arterial bifurcation.

37. The device of claim 36, whereby said at least one radiographic opaque marker is a gold point.

38. The device of claim 1, whereby radially directional elastic forces of said expandable basis element operate to maintain said basis element in said expanded state at the arterial bifurcation.

39. The device of claim 1, whereby the blood flowing at the arterial bifurcation is characterized by Reynolds number, Re, having a value in a range of between about 200 to about 500.

40. The device of claim 1, whereby, during the blood flowing at the arterial bifurcation, physiological conditions at the arterial bifurcation are characterized by Reynolds number, Re, having a value in a range of between about 200 and about 500, and, Womersley parameter having a value in a range of between about 2 and about 7.

41. The device of claim 15, whereby, during the blood flowing at the arterial bifurcation, said deflecting and filtering element is characterized by a wire Reynolds number having a value in a range of between 0 to about 30, in accordance with creeping or Stokes'flow.

42. The device of claim 15, whereby, during the blood flowing at the arterial bifurcation, said deflecting and filtering element is characterized by a wire Reynolds number having a value in a range of between 0 and about 30, in accordance with creeping or Stokes'flow, and, by a wire shear stress having a value in a range of between less than about 100 dyne/cm2 and greater than about 2 dynelcm2.

43. The device of claim 1, whereby the arterial bifurcation is in a region of the common carotid arteries.

44. The device of claim 1, whereby the arterial bifurcation is in a region of the common carotid arteries branching off to the internal carotid artery and branching off to the external carotid artery.

45. The device of claim 1, whereby, for the arterial bifurcation being the common carotid arterial bifurcation, said first branch is the internal carotid artery and said second branch is the external carotid artery.

46. The device of claim 1, whereby said first branch is a vital artery and said second branch is a non-vital artery.

47. A method for deflecting embolic material in blood flowing at an arterial bifurcation, comprising the steps of : (a) providing an implantable composite device featuring (i) a deflecting and filtering element, and, (ii) an expandable basis element for supporting said deflecting and filtering element and for anchoring the composite device at the arterial bifurcation, said basis element is separate from said deflecting and filtering element, whereby an operative composite of said deflecting and filtering element and said basis element forms the implantable composite device having a contracted state with a first diameter and an expanded state having a second diameter greater than said first diameter,

wherein said deflecting and filtering element deflects the embolic material in the blood flowing toward a first branch of the arterial bifurcation into a second branch of the arterial bifurcation, while filtering the blood flowing toward said first branch of the arterial bifurcation ; and (b) implanting and deploying in a vicinity of the arterial bifurcation said implantable composite device.

48. The method of claim 47, whereby said basis element is of a type selected from the group consisting of self-expandable, and, non-self-expandable, at the arterial bifurcation.

49. The method of claim 47, whereby said basis element is self-expandable at the arterial bifurcation.

50. The method of claim 47, whereby said basis element is expandable under pressure supplied by a mechanism operative at the arterial bifurcation.

51. The method of claim 47, whereby said basis element is expandable under pressure supplied by a mechanism separate from and operative with said basis element, at the arterial bifurcation.

52. The method of claim 47, whereby there is at least partial overlap of two opposing ends of said basis element in said expanded state.

53. The method of claim 47, whereby there is no partial overlap of two opposing ends of said basis element in said expanded state, whereby a gap is formed between said two opposing ends of said basis element.

54. The method of claim 47, whereby said basis element is a perforated sheet material.

55. The method of claim 54, whereby said perforated sheet material features a plurality of perforations or apertures for permitting growth of cells from arterial walls onto surface of said basis element, thereby prevent pathological damage to said arterial walls of the arterial bifurcation.

56. The method of claim 47, whereby said basis element is a meshed structure.

57. The method of claim 56, whereby perimeter of said meshed structure is surrounded by an essentially rigid frame.

58. The method of claim 56, whereby said meshed structure is made of braided material.

59. The method of claim 56, whereby said meshed structure is made of flat braided material.

60. The method of claim 56, whereby said meshed structure is made of braided material manufactured from a shaped memory alloy.

61. The method of claim 47, whereby said portion of and integral with said basis element is a finely meshed zone functioning as a deflecting and filtering element, for said deflecting the embolic material in the flowing blood and for said filtering the flowing blood.

62. The method of claim 61, whereby said deflecting and filtering element replaces a substantially equivalently sized portion of said basis element.

63. The method of claim 61, whereby said deflecting and filtering element supplements a substantially equivalently sized portion of said basis element.

64. The method of claim 61, whereby open area of perforations or apertures of perforated sheet material as said basis element is significantly larger than mesh size openings of said deflecting and filtering element required for said deflecting the embolic material in the flowing blood.

65. The method of claim 61, whereby open area or mesh size of meshed structure as said basis element is significantly larger than mesh size openings of said deflecting and filtering element required for said deflecting the embolic material in the flowing blood.

66. The method of claim 47, whereby said first diameter of said basis element in said contracted state is in a range of between about 1 mm to about 4 mm.

67. The method of claim 47, whereby said second diameter of said basis element in said expanded state is in a range of between about 5 mm to about 30 mm.

68. The method of claim 47, whereby said first diameter of said basis element in said contracted state is in a range of between about 1 mm to about 4 mm, and, whereby said second diameter of said basis element in said expanded state is in a range of between about 5 mm to about 30 mm.

69. The method of claim 47, whereby said basis element is constructed from wires having cross-sections of variable geometrical shape and configuration selected from the group consisting of circular, elliptical, square, rectangular, and, combinations thereof.

70. The method of claim 47, whereby said basis element is constructed from material selected from the group consisting of stainless steel, superelastic Nitinol, ElgiloyTM, mixtures of different metals and alloys, polymeric material, and, combinations thereof.

71. The method of claim 47, whereby thickness and diameter of wire used for constructing said basis element are in a range of between about 100 microns to about 1500 microns.

72. The method of claim 47, whereby thickness and diameter of wire used for constructing said basis element are in a range of between about 100 microns to about 200 microns.

73. The method of claim 61, whereby said deflecting and filtering element is constructed from wires having cross-sections of variable geometrical shape and configuration selected from the group consisting of circular, elliptical, square, rectangular, and, combinations thereof.

74. The method of claim 61, whereby said deflecting and filtering element is constructed from material selected from the group consisting of stainless steel, superelastic Nitinol, Elgiloy, mixtures of different metals and alloys ; : polymeric material, and, combinations thereof.

75. The method of claim 61, whereby thickness and diameter of wire used for constructing said deflecting and filtering element are in a range of between about 20 microns to about 75 microns.

76. The method of claim 47, whereby said basis element is positioned along inner walls of an artery of the arterial bifurcation.

77. The method of claim 47, whereby, for the arterial bifurcation being the common carotid arterial bifurcation, said basis element is positioned along inner walls of external carotid artery of the common carotid arterial bifurcation.

78. The method of claim 47, whereby said basis element is used for positioning said deflecting and filtering portion between arterial inner walls at an aperture of the arterial bifurcation.

79. The method of claim 47, whereby, for the arterial bifurcation being the common carotid arterial bifurcation, said basis element is used for positioning said deflecting and filtering portion between arterial inner walls located at aperture of inlet to internal carotid artery of the common carotid arterial bifurcation, thereby extending across and covering said aperture of said inlet to said internal carotid artery.

80. The method of claim 47, whereby said basis element supports and anchors said deflecting and filtering portion between arterial inner walls of an aperture of the arterial bifurcation.

81. The method of claim 47, whereby for the arterial bifurcation being the common carotid arterial bifurcation, said basis element supports and anchors said deflecting and filtering portion between arterial inner walls located at aperture of inlet to internal carotid artery of the common carotid arterial bifurcation, thereby extending across and covering said aperture of said inlet to said internal carotid artery.

82. The method of claim 47, whereby at least one radiographic opaque marker is located at a position on said basis element, for use in positioning said basis element within an artery at the arterial bifurcation.

83. The method of claim 82, whereby said at least one radiographic opaque marker is a gold point.

84. The method of claim 47, whereby radially directional elastic forces of said expandable basis element operate to maintain said basis element in said expanded state at the arterial bifurcation.

85. The method of claim 47, whereby the blood flowing at the arterial bifurcation is characterized by Reynolds number, Re, having a value in a range of between about 200 to about 500.

86. The method of claim 47, whereby, during the blood flowing at the arterial bifurcation, physiological conditions at the arterial bifurcation are characterized by Reynolds number, Re, having a value in a range of between about 200 and about 500, and, Womersley parameter having a value in a range of between about 2 and about 7.

87. The method of claim 61, whereby, during the blood flowing at the arterial bifurcation, said deflecting and filtering element is characterized by a wire Reynolds number having a value in a range of between 0 and about 30, in accordance with creeping or Stokes'flow.

88. The method of claim 61, whereby, during the blood flowing at the arterial bifurcation, said deflecting and filtering element is characterized by a wire Reynolds number having a value in a range of between 0 and about 30, in accordance with creeping or Stokes'flow, and, by a wire shear stress having a value in a range of between less than about 100 dyne/cm2 and greater than about 2 dyne/cm2.

89. The method of claim 47, whereby the arterial bifurcation is in a region of the common carotid arteries.

90. The method of claim 47, whereby the arterial bifurcation is in a region of the common carotid arteries branching off to the internal carotid artery and branching off to the external carotid artery.

91. The method of claim 47, whereby, for the arterial bifurcation being the common carotid arterial bifurcation, said first branch is the internal carotid artery and said second branch is the external carotid artery.

92. The method of claim 47, whereby said first branch is a vital artery and said second branch is a non-vital artery.

93. Use of an implantable composite device in the manufacture of a medical device for deflecting embolic material in blood flowing at an arterial bifurcation, for preventing the occurrence of a condition associated with the embolic material in a subject, comprising implanting and deploying the implantable composite device at an arterial bifurcation of the subject, the implantable composite device comprising:

(a) a deflecting and filtering element; and (b) an expandable basis element for supporting said deflecting and filtering element and for anchoring the device at the arterial bifurcation, said basis element is separate from said deflecting and filtering element, whereby an operative composite of said deflecting and filtering element and said basis element forms the implantable composite device having a contracted state with a first diameter and an expanded state having a second diameter greater than said first diameter, wherein said deflecting and filtering element deflects the embolic material in the blood flowing toward a first branch of the arterial bifurcation into a second branch of the arterial bifurcation, while filtering the blood flowing toward said first branch of the arterial bifurcation.

94. Use of an implantable composite device in the manufacture of a medical device for deflecting embolic material in blood flowing at an arterial bifurcation, for treating a subject with a condition associated with the embolic material, comprising implanting and deploying the implantable composite device at an arterial bifurcation of the subject, the implantable composite device comprising:

95. A method for deflecting embolic material in blood flowing at an arterial bifurcation, for preventing the occurrence of a condition associated with the embolic material in a subject, comprising the steps of : (a) providing an implantable composite device featuring (i) a deflecting and filtering element, and, (ii) an expandable basis element for supporting said deflecting and filtering element and for anchoring the composite device at the arterial bifurcation, said basis element is separate from said deflecting and filtering element, whereby an operative composite of said deflecting and filtering element and said basis element forms the implantable composite device having a contracted state with a first diameter and an expanded state having a second diameter greater than said first diameter,

wherein said deflecting and filtering element deflects the embolic material in the blood flowing toward a first branch of the arterial bifurcation into a second branch of the arterial bifurcation, while filtering the blood flowing toward said first branch of the arterial bifurcation; and (b) implanting and deploying in a vicinity of the arterial bifurcation of the subject said implantable composite device.

A method for deflecting embolic material in blood flowing at an arterial for treating the occurrence of a condition associated with the embolic material , comprising the steps of : providing an implantable composite device featuring (i) a deflecting and filtering element, and, (ii) an expandable basis element for supporting said deflecting and filtering element and for anchoring the composite device at the arterial bifurcation, said basis element is separate from said deflecting and filtering element, whereby an operative composite of said deflecting and filtering element and said basis element forms the implantable composite device having a contracted state with a first diameter and an expanded state having a second diameter greater than said first diameter,

wherein said deflecting and filtering element deflects the embolic material in the blood flowing toward a first branch of the arterial bifurcation into a second branch of the arterial bifurcation, while filtering the blood flowing toward said first branch of the arterial bifurcation ; and implanting and deploying in a vicinity of the arterial bifurcation of the subject said implantable composite device.

The method of claim 96, whereby the condition is a cerebralvascular The method of claim 97, whereby said cerebralvascular disease is a stroke.

The method of claim 96, whereby the condition is an aneurysm.