INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference.

BACKGROUND OF THE INVENTION

This invention relates generally to medical devices used during vascular intervention, and more particularly, concerns medical devices that are useful in treating aortic valve replacement, thromboembolic disorders and for removal of foreign bodies in the vascular system.

Thromboembolic disorders, such as stroke, pulmonary embolism, peripheral thrombosis, atherosclerosis, and the like, affect many people. These disorders are a major cause of morbidity and mortality in the United States and throughout the world. Thromboembolic events are characterized by an occlusion of a blood vessel. The occlusion can be caused by a clot which is viscoelastic (jelly-like) and is comprised of platelets, fibrinogen, and other clotting proteins.

Percutaneous aortic valve replacement has been in development for some time now and stroke rates related to this procedure are between four and twenty percent. During catheter delivery and implantation plaque may be dislodged from the vasculature. The invention contained within will block the emboli from traveling through the carotid circulation and onto the brain. When an artery is occluded by a clot, tissue ischemia (lack of oxygen and nutrients) develops. The ischemia will progress to tissue infarction (cell death) if the occlusion persists. Infarction does not develop or is greatly limited if the flow of blood is reestablished rapidly. Failure to reestablish blood-flow can lead to the loss of limb, angina pectoris, myocardial infarction, stroke, or even death.

Occlusion of the venous circulation by thrombi leads to blood stasis which can cause numerous problems. The majority of pulmonary embolisms are caused by emboli that originate in the peripheral venous system. Reestablishing blood flow and removal of the thrombus is highly desirable.

There are many existing techniques employed to reestablish blood flow in an occluded vessel. One common surgical technique, an embolectomy, involves incising a blood vessel and introducing a balloon-tipped device (such as a Fogarty catheter) to the location of the occlusion. The balloon is then inflated at a point beyond the clot and used to translate the obstructing material back to the point of incision. The obstructing material is then removed by the surgeon. While such surgical techniques have been useful, exposing a patient to surgery may be traumatic and is best avoided when possible. Additionally, the use of a Fogarty catheter may be problematic due to the possible risk of damaging the interior lining of the vessel as the catheter is being withdrawn.

A common percutaneous technique is referred to as balloon angioplasty where a balloon-tipped catheter is introduced into a blood vessel, typically through an introducing catheter. The balloon-tipped catheter is then advanced to the point of the occlusion and inflated in order to dilate the stenosis. Balloon angioplasty is appropriate for treating vessel stenosis but is generally not effective for treating acute thromboembolisms.

Another percutaneous technique is to place a microcatheter near the clot and infuse Streptokinase, Urokinase, or other thrombolytic agents to dissolve the clot. Unfortunately, thrombolysis typically takes hours to days to be successful. Additionally, thrombolytic agents can cause hemorrhage and in many patients the agents cannot be used at all.

Another problematic area is the removal of foreign bodies. Foreign bodies introduced into the circulation can be fragments of catheters, pace-maker electrodes, guide wires, and erroneously placed embolic material such as thrombogenic coils. There exist retrieval devices for the removal of foreign bodies, certain of such devices form a loop that can ensnare the foreign material by decreasing the size of the diameter of the loop around the foreign body. The use of such removal devices can be difficult and sometimes unsuccessful.

Moreover, systems heretofore disclosed in the art are generally limited by size compatibility and the increase in vessel size as the emboli is drawn out from the distal vascular occlusion location to a more proximal location near the heart. If the embolectomy device is too large for the vessel it will not deploy correctly to capture the clot or foreign body, and if too small in diameter it cannot capture clots or foreign bodies across the entire cross section of the blood vessel. Additionally, if the embolectomy device is too small in retaining volume then as the device is retracted the excess material being removed can spill out and be carried by flow back to occlude another distal vessel.

Various thrombectomy and foreign matter removal devices have been disclosed in the art. However, such devices have been found to have structures which are either highly complex or lacking in sufficient retaining structure. Disadvantages associated with the devices having highly complex structure include difficulty in manufacturability as well as difficulty in use in conjunction with microcatheters. Recent developments in the removal device art features umbrella filter devices having self folding capabilities. Typically, these filters fold into a pleated condition, wherein the pleats extend radially and can obstruct retraction of the device into the micro catheter sheathing.

What has been needed and heretofore unavailable is an extraction device that can be easily and controllably deployed into and retracted from the circulatory system for the effective removal of clots and foreign bodies. There is also a need for a system that can be used as a temporary arterial or venous filter to capture and remove thromboemboli generated during endovascular procedures. Moreover, due to difficult-to-access anatomy such as the cerebral vasculature and the neurovasculature, the invention should possess a small collapsed profile and preferably be expandable to allow the device to be delivered through the lumen of commercially available catheters. The present invention satisfies these needs.

SUMMARY OF THE INVENTION

Most filter devices are delivered from the groin and are placed distal to the flow of the lesion or site in question. Single basket-type filters or Nitinol loop filters are the most common used today in carotid stent procedures of vein graft stenting. As the guidewire is delivered past the lesion the filter is delivered over the guidewire protecting the distal vasculature. The invention here may be delivered from the groin in a conventional manner to vessels such as the carotid arteries or via radial (arm vasculature) approach. Protecting the carotid arteries and cerebral vasculature system is the main goal while leaving the aortic arch free from catheters and wire as much as possible during the delivery of other devices such as aortic balloons and prosthetic valves or other associated devices.

One method of filtering the carotid arteries leaving the aorta free from obstruction is to deliver a filter to each of the carotid arteries from the groin leaving them in the carotid vasculature and retrieving them via snare post procedure. A delivery catheter would be inserted through an introducer in the groin (femoral artery) and delivered to the common carotid arteries and detached. The delivery catheter would be removed and a second filter would be delivered in a similar manner to the other carotid artery. With two detached filters now in place the procedure treating the aortic or mitral valve can now be completed with embolic protection for the cerebral vascular system. Once the procedure to the valve is completed, the filters can be snared and retrieved back out the femoral artery as they were delivered. Any embolic particles will be captured in the filter device and removed safely from the body.

Another method for filtering the carotid arteries would be to deliver a filter from the femoral artery and utilize a single catheter to house the two attachment means to the filters. These attachments may be a wire similar to a guidewire or a hypo-tube to connect the filter element to an external portion of the body. Keeping these wires or connection means organized and contained within a single or dual lumen catheter will help organize and limit potential entanglement with other catheters being delivered to the target site such as the aortic valve or other cardiac elements including but not limited to the mitral valve and coronary arteries. The distal portion of the catheter may have a single exit portion or a staggered exit to allow an exit at different points along the catheter. One exit port may be at the distal most end of the catheter and the other may be a centimeter proximal from this to allow the attachment wire to exit near the left common carotid artery. Furthermore, there could be an extension to the distal most portion of the catheter allowing side ports for both wires to exit. This would allow for additional catheter stabilization within the aorta.

Another embodiment would deliver filters to the carotid from the radial artery and allow for a clear aortic arch from catheters and other delivery means from a more conventional femoral delivery means. From this access site a plurality of filters could be delivered through a common access sheath or the filters could be delivered from a dual lumen catheter with each lumen housing a single filter.

Another delivery means would utilize a single catheter with filters mounted in a coaxial manner where the distal filter would be delivered first and could be mounted to a wire where the second would be mounted to a hypo-tube where the first filters wire would run through the second allowing for relative motion between the two filters. The first filter would be delivered to the left common carotid from the radial artery and the second would be delivered to the right common carotid artery or the brachiocephalic trunk in a coaxial manner. These filters would be opposed in direction as the distal filter would be filtering blood flowing from the base of the aorta to the head and toward the distal end of the guidewire. The proximal filter would be filtering blood from the base of the aorta to the head and toward the proximal end of the guidewire. Placing the two filters together there would be a conical shape configuration where the large diameter portions of the cones would meet. These two filters would be delivered in a collapsed configuration and expanded when expelled from the delivery catheter. Retrieval would be a retraction of the filter back into a recovery catheter that would be a larger inner diameter than the delivery catheter to allow room for particulate. Being opposed in capture direction the right carotid would be the first filter that would be recovered by an expanded sheath where the embolic material would not be disturbed and further withdrawn to a smaller sheath for removal from the body. The expanded sheath could be constructed from braided Nitinol wire pre-shaped so when exposed the braid would expand to receive the filter without squeezing out any trapped emboli. The second or left carotid filter would be recovered in a conventional manner where the larger diameter would be pulled into a sheath to trap and remove the emboli within the tailor distal portion of the filter.

Another means to deliver the filters via radial artery approach would be to utilize a dual lumen catheter where each lumen would house a single filter. The first lumen would deliver a filter to the left carotid artery and the second lumen would deliver a filter to the right carotid artery. The lumens could be staggered in length to reach each ostium in which case the first or left filter lumen would be longer in length to allow for placement distal from the second filter placement in the right carotid. Additionally, the second lumen may be pre-shaped with a curve to allow easy access to the right carotid artery. This pre-shaped curve may be retained in a straighter manner to allow for delivery and released to express the delivery shape when at the bifurcation of the subclavian and the carotid artery. Furthermore, there may be an active shaping where the curve is directed external to the body by a handle mechanism such as a pull-wire where tension would generate a compressive force to the catheter column preferentially bending the lumen. Recovery could utilize the same dual lumen concept or utilize a second recovery sheath independently from one another.

Another application for this device and method would be for surgical operations where the patient may be put on heart-lung bypass. During cross clamping of the aorta catheters or wires in the aorta may interfere with the procedure and allow leakage of blood around the cannulas used. If any of the above described devices or techniques are used before the patient's chest is opened this filtration of the carotid vessels would protect from emboli thus reducing the stroke risk during and after the procedure. Additional anti thrombotic coatings to the filter could allow for an extended implantation time allowing filtration time to be extended post procedure. An example of this coating would be Heparin. Placement of these catheters and filters could be under fluoroscopy or ultrasound guidance to direct proper filter placement. Radiopaque markers may add necessary visibility to the catheter, filter and or wires.

Another surgical delivery means would be an insertion to the carotid artery via the neck. The filter could face either antigrade or retrograde depending upon the placement insertion point or access site. This would allow for complete filtration without any aortic interference as the entire devices would be within the carotid circulation. With this delivery technique the puncture site would be very small and recovery could be through the entry site or through the groin as the filter could be inserted distal to meet a recovery sheath in the aorta. With this groin recovery any emboli within the proximal carotid would be captured before later dislodgement.

Intravascular filters have been used in many configurations ranging from a windsock style as commercialized as the FilterWire from Boston Scientific or the ACCUNET from Abbott Vascular or the Spider from eV3. These filters utilize a memory metal such as Nitinol is used to oppose the vascular wall tightly sealing any emboli from passage while a filter material such as a porous fabric material retains and emboli from passing distally from the device. Another example is a laser cut memory metal where the basket is the frame and the filter is used to trap emboli when expanded. Another example is constructed from a braided wire such as Medtronic's Interceptor PLUS where once exposed the braid expands to create a funnel or cone shape to trap emboli and the proximal or larger end is pre-shaped to accept blood flow with larger openings heat-set into the memory metal such as Nitinol. These filters range in diameter from about 2-15 mm in diameter and are approximately 20-30 mm in length. They are generally attached to a guidewire and sheathed for delivery and resheathed for recovery. The catheter profile measures about 1 to 2 mm in diameter and has a length of about 90 to 200 cm. Catheter construction is normally a polypropylene or polyethylene material but nylons and blends can be used as well. All devices are considered single use and are commonly placed for carotid stenting or savenous vein grafts stenting.

