Surgery – Instruments – Internal pressure applicator
Reexamination Certificate
2001-08-27
2003-11-11
Milano, Michael J. (Department: 3731)
Surgery
Instruments
Internal pressure applicator
C606S194000, C606S159000
Reexamination Certificate
active
06645224
ABSTRACT:
INTRODUCTION
The invention relates to an embolic protection device.
The term “STROKE” is used to describe a medical event whereby blood supply to the brain or specific areas of the brain is restricted or blocked to the extent that the supply is inadequate to provide the required flow of oxygenated blood to maintain function. The brain will be impaired either temporarily or permanently, with the patient experiencing a loss of function such as sight, speech or control of limbs. There are two distinct types of stroke, haemorrhagic and embolic. This invention addresses embolic stroke.
Medical literature describes carotid artery disease as a significant source of embolic material. Typically, an atherosclerotic plaque builds up in the carotid arteries. The nature of the plaque varies considerably, but in a significant number of cases pieces of the plaque can break away and flow distally and block bloodflow to specific areas of the brain and cause neurological impairment. Treatment of the disease is classically by way of surgical carotid endarterectomy whereby, the carotid artery is cut and the plaque is physically removed from the vessel. The procedure has broad acceptance with neurological complication rates quoted as being low, somewhere in the order of 6% although claims vary widely on this.
Not all patients are candidates for surgery. A number of reasons may exist such that the patients could not tolerate surgical intervention. In these cases and an increasing number of candidates that are surgical candidates are being treated using transcatheter techniques. In this case, the evolving approach uses devices inserted in the femoral artery and manipulated to the site of the stenosis. A balloon angioplasty catheter is inflated to open the artery and an intravascular stent is sometimes deployed at the site of the stenosis. The action of these devices as with surgery can dislodge embolic material which will flow with the arterial blood and if large enough, eventually block a blood vessel and cause a stroke.
It is known to permanently implant a filter in human vasculature to catch embolic material. It is also known to use a removable filter for this purpose. Such removable filters typically comprise umbrella type filters comprising a filter membrane supported on a collapsible frame on a guidewire for movement of the filter membrane between a collapsed position against the guidewire and a laterally extending position occluding a vessel. Examples of such filters are shown in U.S. Pat. Nos. 4,723,549, 5,053,008, 5,108,419 and WO 98/33443. Various deployment and/or collapsing arrangements are provided for the umbrella filter. However, as the filter collapses, the captured embolic material tends to be squeezed outwardly towards an open end of the filter and pieces of embolic material may escape from the filter with potentially catastrophic results. More usually, the filter umbrella is collapsed against the guidewire before removal through a catheter or the like. Again, as the filter membrane is collapsed, it will tend to squeeze out the embolic material. Further, the umbrella filter is generally fixed to the guidewire and any inadvertent movement of the guidewire during an interventional procedure can dislodge the filter.
The present invention is directed towards overcoming these problems.
There is a need for an embolic protection device which will overcome this problem.
STATEMENTS OF INVENTION
According to the invention, there is provided an embolic protection device comprising:
a collapsible filter element mounted on a filter carrier for delivery through a vascular system of a patient,
the filter element being movable between a collapsed stored position against the filter carrier for movement through the vascular system, and an expanded position for occluding a blood vessel such that blood passing through the blood vessel is delivered through the filter element,
the filter element comprising a collapsible filter body having an inlet end and an outlet end,
the inlet end of the filter body having one or more inlet openings sized to allow blood and embolic material enter the filter body,
the outlet end of the filter body having a plurality of outlet openings sized to allow through passage of blood but to retain undesired embolic material within the filter body,
means for closing the inlet openings at he inlet end of the filter body, and means for collapsing the filter body on the support.
Advantageously, the inlet openings in the filter are closed before the filter is collapsed ensuring retention of all embolic material within the filter element.
In a particularly preferred embodiment of the invention, the means for closing the inlet comprises:
a tubular filter retrieval device having an open distal end for reception of the filter element,
said distal end being engagable with a proximal inlet end of the filter body to close the inlet openings and being slidable over the filter body from the inlet end to the outlet end to progressively collapse the filter body on the filter carrier and receive the filter body within the retrieval device.
Conveniently, the retrieval device which may be a catheter or pod or the like which engages and collapses the filter element firstly closing the inlet openings to prevent any escape of embolic material and then collapsing the remainder of the filter, being slid from the proximal end over the filter to the distal end of the filter.
In a particularly preferred embodiment, the collapsible filter element is slidably mounted on the filter carrier between the a pair of spaced-apart stops on the filter carrier for axial movement of the filter element along the filter carrier between the stops.
Advantageously, the filter carrier which may for example be a guidewire can be moved independently of the filter element and thus accidental movement of the guidewire is accommodated without unintentionally moving the filter, for example, during exchange of medical devices.
In a further embodiment, the filter element is rotatably mounted on the filter carrier.
In a preferred embodiment, a sleeve is slidably mounted on the filter carrier between the stops, the length of the sleeve being less than the distance between the stops, the filter element being mounted on the sleeve.
In a particularly preferred embodiment, the filter element comprises:
a collapsible filter net mounted on the filter carrier,
the filter net being movable between a collapsed stored position against the filter carrier and an expanded position extending outwardly of the filter carrier for deployment across a blood vessel.
Preferably, the tubular filter retrieval device comprises a catheter slidable along the filter carrier, an open distal end of the catheter forming a housing for reception of the filter element.
In another embodiment, a proximal inlet end of the filter body is fixed to the filter carrier and a distal end of the filter body is slidably mounted on the filter carrier, although this arrangement may be reversed.
In a further embodiment, the distal end of the filter body is attached to a collar which is slidable along the filter carrier.
In a preferred embodiment, a filter support frame is mounted on the filter carrier, the support frame being movable between a collapsed position along the filter carrier and an extended outwardly projecting position to support the filter body in the expanded position.
In another embodiment, the filter support frame is fixed on the filter carrier at a proximal end of the filter body.
Preferably, the filter support frame slidably engages the filter carrier at a distal end of the filter body. Ideally, the filter support frame is biased into a normally extended position.
In a further embodiment, a circumferential groove is provided in the filter body intermediate the ends of the filter body.
In another embodiment, a guide olive is provided on the filter carrier distally of the fitter body, the guide olive having a cylindrical body with a tapered distal end, the cylindrical body being engagable within a distal end of a deployment catheter, said tapered distal end proj
Brady Eamon
Gilson Paul
Maher Padraig
Taylor Charles
Vale David
Burns Doane , Swecker, Mathis LLP
Milano Michael J.
Salviac Limited
Webb Sarah
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