APPARATUS AND PROCEDURE FOR TRAPPING EMBOLIC DEBRIS
A collapsible and deployable filter for blocking debris and passing blood in a blood vessel in a patient's body, the filter including; a framework of a flexible material, constructed to have a radially compressed state, in which the framework is radially compressed by radial deforming forces, and a radially expanded state to obdurate an artery; and a flexible filter material secured to said framework and having pores dimensioned to prevent the passage of debris therethrough while allowing the passage of blood. The filter has, in the radially expanded state of the framework, a generally conical or frustoconical form with a large diameter end, a small diameter end opposite to the large diameter end, and a side surface extending between the ends. The filter has an opening that is free of filter material at the small diameter end or in the side surface.
The present invention relates to an apparatus and procedure for aiding medical treatments in the blood circulation system of a patient, and in particular for preventing the circulation of embolic debris, or blood clots, resulting from such treatments. The invention is primarily, but not exclusively, concerned with providing protection in connection with procedures like those for implanting a prosthetic heart valve.
There are known procedures, known as transcatheter aortic valve implantation (TAVI), in which a prosthetic heart valve is implanted at the site of a defective native valve, or of a previously implanted defective prosthetic valve. In these procedures, the new prosthetic valve and its guiding structure are introduced by a transcutaneous catheterization technique. For example, for implanting a prosthetic aortic heart valve, the valve and delivery components will be introduced through an incision in the groin or arm and along a blood vessel path to the desired location.
Such a procedure is disclosed, for example, in U.S. Pat. No. 7,585,321, which issued to Alan Cribier on Sep. 8, 2009, the entire disclosure of which is incorporated herein by reference. Such valves and their associated guiding devices are marketed by Medtronic and by Edwards Lifesciences, one example of the Edwards valves being marketed under the trade name Sapien.
Although such prosthetic valves have been used successfully to provide a replacement for stenotic native heart valves or defective prosthetic valves, the implantation procedure can result in the creation of embolic debris, which will flow downstream through the circulatory system and will, in a certain percentage of cases, cause blockages in smaller blood vessels.
BRIEF SUMMARY OF INVENTIONThe present invention provides an apparatus and procedure to prevent the circulation of embolic debris resulting from procedures carried out in the blood circulatory system, one such procedure being, for example, the implantation of a prosthetic heart valve.
To this end, the invention provides a novel filter and a novel combination of such filter and a blocking device for trapping embolic debris produced during such a medical procedure. It also provides the filter with a central, or axial, orifice through which the valve implantation device, or system, can be directed, which facilitates this process and reduces the traumatic effects of the valve implantation device on the wall of the aorta. Since it is known that trauma to the aortic wall generates clots and calcium, the position of the orifice in the filter acts as a landmark and facilitates atraumatic entry of the valvular device.
The invention also provides, together with the filter and blocking device, a stent or stent graft that is preliminarily deployed against the inner wall of the blood vessel, e.g., the aorta, to prevent trauma during introduction of the filter.
In further accordance with the invention, the filter can be delivered in, deployed from and retracted into, a known radially expandable sheath provided particularly to facilitate retraction of the filter.
In further accordance with the invention, there is provided a filter system for preventing the flow of debris in the pulmonary artery during heart surgery, such as congenital heart surgery.
The components of embodiments of the invention may be conveyed to the treatment site along various blood vessel paths and may all be introduced via the same path or via respectively different paths. For example, if the components are to be positioned in, or pass through, the aorta, the, or each, component can be introduced through an incision in a groin and the associated femoral artery, or through an incision in an arm and the associated subclavian artery.
Filter 2 has a generally cylindrical structure with a small diameter end, at the top in
According to a presently preferred embodiment of the invention, the large diameter end of filter 2 is formed to have a generally oval shape with a major diameter of about 40 mm and a minor diameter of the order of 30 mm This allows the lower end of the filter to better conform to the somewhat oval shape of a normal aorta.
Of course, the dimensions of filter 2 can be varied to conform to aortas having different sizes, for example in children.
Filter 2 has a form defined by an outwardly bowed arcuate generatrix of rotation about the longitudinal axis of filter 2 such that the wall of the filter bows outwardly, as shown in
The framework of the illustrated embodiment is composed of a single wire that includes a ring 4a at the small diameter end, a series of longitudinal struts, or ribs, 4b, and a control portio 4c that extends to a location outside of the patient's body to allow the position of filter 2 to be controlled by medical personnel. The framework further includes a circumferential band 4d at a location between the small diameter end and the large diameter end. The framework may also include a circular or oval nitinol ring extending around the large diameter end and bonded to the lower ends of ribs 4b.
Filters composed of a framework of memory metal, e.g. nitinol, wires can be constructed to present a radial expansion/compression ratio of 8:1, or more. Therefore, they will be held, in a compressed state in a sheath or tube having an inner diameter preferably equal to or greater than ⅛ the desired expanded diameter of the large diameter end of the filter.
While
The structure shown in
Filter fabrice 6 can be of any medically acceptable material having appropriate mechanical properties and pore size suitable for trapping debris while allowing the passage of blood therethrough. Examples of suitable materials for the framework and the filter fabric are described in, for example, U.S. Pat. No. 7,214,237, the entire disclosure of which is incorporated herein by reference.
The components shown in
In
The apparatus associated with filter 2 includes a guidewire 30 that is introduced transcutaneously and then along a blood vessel path into the aorta and through the center of the native or previously implanted heart valve. Guidewire 30 is then used to guide the introduction of a sheath, or tube, 32 along the same blood vessel path and into aorta 20 to bring the distal end of sheath 32 adjacent the existing valve. During introduction, filter 2 is collapsed within sheath 32. Then, when sheath 32 has been brought into the desired position in aorta 20, for example adjacent the interface between the aorta and the existing heart valve, guidewire 30 can be withdrawn and sheath 32 can be withdrawn, at least by a distance to not interfere with the valve implantation procedure, while filter 2 is held in place by acting on control portion 4c, or the plural control wires, from outside the patient's body so that filter 2 is freed from sheath 32. Filter 2 is thus automatically deployed, or expanded, and placed in the position and configuration shown in
Sheath 32 also contains a catheter 40 provided at its distal end with a low compliance, or noncompliant, blocking balloon 44. Catheter 40 also includes, in a conventional manner, a balloon inflation lumen in communication with balloon 44. Catheters provided with such lumens are well known in the art. One example being U.S. Pat. No. 7,169,171, the entire disclosure of which is incorporated herein by reference. Catheter 40 may have a diameter as small as 4 Fr. (1.3 mm)
After filter 2 has been deployed, catheter 40 is advanced along guidewire 10 to bring balloon 44 to the location 44a shown in broken lines in
At a time after filter 2 has been deployed, guidewire 30 and sheath 32 can be withdrawn from the patient's body.
Then, an assembly 60 for implanting the prosthetic heart valve is introduced into the aorta, preferably, but not necessarily, via a different blood vessel path, by first passing a guidewire 62 along that blood vessel path through the center of filter 2 and through the existing heart valve. Assembly 60 includes, in addition to guidewire 62, a sheath, or tube, 64 and a system 66 including the prosthetic heart valve and components for deploying it
After guidewire 62 is put in place, tube 64 is introduced into the aorta over guidewire 62 to a location adjacent filter 2, after which system 66 is extended out of tube 64 and through ring 4a of filter 2 and along the central orifice defined by filter 2, for implanting the prosthetic heart valve. System 66 and one suitable manner in which it is used to implant a prosthetic heart valve are all described in detail in U.S. Pat. No. 7,585,321, the entire disclosure of which is incorporated herein by reference.
Valve assembly 60 can be inserted by puncturing an artery in the groin and advancing it upwards through the femoral artery and the aorta, followed by advancing system 66 through the existing valve.
The valve assembly could also be introduced through either the right or left subclavian artery, which normally supplies an upper extremity. Consequently, there is the option of introducing sheath 32 and filter 2 through either subclavian artery or through the femoral artery. In general, it is presently preferred to use one of these paths, the subclavian artery or femoral artery, for introducing sheath 32, and the other of these paths for valve assembly 60. Since sheath 32 can have a smaller diameter, it might be advantageous to advance it through the subclavian artery path.
It is presently believed by workers in the art to not be desirable to use the same route for introducing both the valve implantation assembly and the filter assembly due to the fact that every trial done so far has criticized the valve assembly alone as being relatively thick and traumatic in the process of puncturing the artery. The only acceptable single route, which is not favored by patients, is to puncture the heart. For all these reasons, the diameter of valve assembly 60 has been reduced in Europe to 18 mm, although this is not yet approved by the USFDA.
It is important to note that the valve assembly is a cylindrical, relatively rigid structure below which the valve hangs, crimped on an angioplasty balloon, and that expansion of the valve is produced by inflating the angioplasty balloon in the case of the Edwards device and by pulling on the valve using nitinol bands in the case of a Medtronic device.
Neither of these techniques interferes with the use of the filter assembly according to the present invention, which serves to isolate the carotids and other parts of the blood circulatory system from debris that is released during and after implantation of the prosthetic valve, regardless of which valve implantation technique is used.
During implantation of the heart valve, tube 64 can bear against the opening at the top of filter 2 to help prevent the passage of embolic debris and to stabilize the position of the filter. Filter 2, sheath 32 and wire 10 are oriented to cause wire 10 to extend into filter 2, adjacent ring 4a, at a location to not interfere with the positioning of tube 64.
Balloon 44 may be partially inflated with radioactive contrast fluid before withdrawal of the components 66 for implanting the heart valve and tube 64; and immediately after withdrawal of those components, balloon 44 is further inflated, if this was not previously done, and pulled back by acting on catheter 40 from outside the patient's body to cause balloon 44 to block the small diameter opening of filter 2. The presence of radioactive contrast fluid allows the position of balloon 44 to be monitored fluoroscopically.
Inflated balloon 44 acts to close the smaller diameter hole in filter 2 as soon as the prosthetic valve introduction system is retracted out of the filter, thus enabling debris to be trapped adjacent the smaller diameter end of the filter.
Then, after a suitable period of time has elapsed, during which debris can become trapped in filter 2, filter 2 and balloon 44 are drawn into sheath 32 by pulling on control portion 4c, or the plural control wires, if provided, and catheter 40 and tube 64, along with all of the associated components, are withdrawn from the patient's body.
More specifically, balloon 44 will remain inflated and lodged in the smaller diameter opening of filter 2 during an initial phase of withdrawal so that filter 2 and catheter 40 will be pulled toward sheath 32 as a unit. Then, when the smaller diameter end of filter 2 reaches sheath 32, balloon 44 will be deflated and catheter 40 may be partially or fully retracted so that balloon 44 moves out of contact with filter 2. Then, filter 2 can be retracted into sheath 32; and then sheath 32, containing catheter 40 and filter 2, can be fully withdrawn from the patient. During this withdrawal procedure, suction may be applied through sheath 32 to assist the removal of any embolic debris from filter 2.
As an alternative to using a wire 10 to introduce balloon catheter 40, it would be possible to simply use a small diameter catheter with a balloon at the end, surrounding the catheter wall and communicating with a balloon inflation lumen formed in the catheter, to close the opening, or orifice, at the top of filter 2 as soon as valve assembly 60 is pulled out of the filter, thereby preventing escape of emboli. This small diameter catheter may be introduced with the aid of a guidewire that extends though the catheter.
The fact that filter 2 is open at the top offers the advantage of preventing the filter from being blown out of position by the relatively forceful blood flow being produced by the heart as it pumps the blood.
The radiopaque fluid used to inflate balloon 44 will enable the balloon to be readily observed.
Inflated balloon 44 will also serve as a means for partially altering the configuration of the filter and making it parallel to and in line with sheath 32 to facilitate retraction of filter 2 into sheath 32 after completion of the procedure.
The lower portion is also composed of a series of longitudinal struts, or ribs, 74b extending between rings 74a and 74c, and a circumferential band 74d at a location between rings 74a and 74c. Preferably, as in the case of the embodiment of
Struts 74b, like struts 4b of
The upper portion of filter 72, between rings 74c and 74f, is provided with a plurality of longitudinal struts, or ribs, 74e. Preferably, struts 74e curve in the opposite direction from struts 74d so that struts 74e are outwardly concave when the filter is deployed. However, struts 74e can also be constructed to have a straight form when the filter is deployed.
The framework of filter 72 is completed by, preferably, four wires 74g constituting a control portion performing the same function as control portion 4c shown in
Like the embodiment shown in
Also like the embodiment of
Also shown in
Preferably, ring 74f is dimensioned to provide a close fit with tube 64. Optionally, the distal end of tube 64 can be slightly tapered to allow introduction of tube 64 into the upper portion of filter 72, while assuring the establishment of a tight fit with ring 74f, and possibly to provide a sealed connection between tube 64 and ring 74f, thereby preventing the escape of embolic debris from filter 72 during valve implantation.
The manner in which filter 72 is used will be explained with reference to
Filter 72 is employed together with system 60, sheath 32, catheter 40 and low compliance or noncompliant balloon 44, all of which are shown in
After filter 72 has been installed and positioned to surround the entire region through which the replacement valve will be deployed, catheter 40 carrying balloon 44 is advanced over guidewire 10 to the location shown in
Then, system 66 is operated to install the replacement heart valve.
At the completion of this operation, after system 66 has been withdrawn back into tube 64, balloon 44 is at least partially inflated and catheter 40 is withdrawn to bring balloon 44 into contact with ring 74c. Before or after balloon 44 has been brought to the proper position, it may be further inflated in order to form a tight seal at the location of ring 74c. Then assembly 60 can be fully withdrawn, after which filter 72, with balloon 44 still in place and inflated, begins to be withdrawn into sheath 32 by pulling on control wires 74g.
After the top portion of filter 72 has been introduced into sheath 32, balloon 44 is deflated while, preferably, suction is produced within sheath 32 in order to withdraw any debris being held within filter 72.
After deflation of balloon 44, filter 72 and catheter 40 are completely withdrawn into sheath 32, and sheath 32 can then be withdrawn from the patient's body.
The invention as described above offers a number of other advantages. For example, it will allow injection of clot lysing material into the filter and if catheter 40 is provided with an orifice above filter 2, it can be used to continuously monitor the arterial blood pressure.
The filter disclosed herein may also be used to trap embolic debris, or blood clots, in other procedures, such as in treating children or young adults with congenital heart disease who have pulmonary stenosis and on whom is performed a similar procedure that may generate blood clots.
In
Balloon 44 should be one with a reasonably low compliance such that it does not rupture and does not expand the bottle neck, which is preferably made of nitinol but has a firm surface.
The components of the embodiment shown in
A further embodiment of the invention is shown in
According to this embodiment, components 60 and 80, to be described below, can be introduced along the same path, for example along the femoral artery and into the aorta via an incision made in the groin, or through one subclavian artery, as described earlier herein.
The components shown in
Sheath 68 contains a filter 80 somewhat similar to filter 2 shown in
Filter 80, which will be described in greater details below with reference to
After sheath 64 has been brought to its desired position in the aorta, sheath 68 will be advanced to bring its lower, or distal, end to a location close to the defective heart valve, at least approximately where the lower end of filter 80 is to be deployed. Then, sheath 68 is retracted while filter 80 is held in place by a holding force, possibly manual, on control wires 82. As filter 80 thus exits the lower end of sheath 68, the filter expands while it is being deployed to bring it to the desired position to collect debris.
Then, sheath 68 may be withdrawn from the patient's body.
Referring now to
Filters having a nitinol frame can generally expand radially by a maximum factor of 8 and filter 80 is dimensioned so that in the deployed, or expanded state, lower ring 86 has a diameter of the order of 32 mm and upper ring 84 has a diameter of the order of 7 mm Sheath 64 is brought to a position in which, as shown in
After filter 80 has been thus deployed and sheath 64 has been brought into the position shown in
Typically, introduction of system 66 will be aided by a guidewire such as guidewire 62 shown in
During implantation of the heart valve, debris will be released and this debris will be confined by filter 80 and will be carried off with blood through sheath 64 to a suction device located outside of the patient's body. This blood and debris can pass through at a conventional device such as a Coulter counter, which detects and counts the debris particles. Suction will be continued until the output of the measuring device indicates that no further debris is present in the blood flow.
With the arrangement shown in
After such an indication has been produced, filter 80 can be withdrawn, by acting on the control wires 82, into sheath 64 and all components can then be withdrawn from the patient's body.
After filter 80 has been deployed at the desired location, a guidewire (not shown) is introduced , for example through the groin or the subclavian, and then passed though ring 88 into the region enclosed by filter 80.
Outside of the patient's body, debris in the blood exiting thought the top of filter 80 can be filtered out of the blood and the filtered blood can be returned to the patient's circulatory system, as will be described subsequently herein.
A further embodiment of the invention is illustrated in
Filter 90 is provided with a control wire 92 at its apex, where it is closed. Filter 90 can be introduced through a subclavian artery, for example the left subclavian artery.
Filter 90 is provided with an entry cone 100 and a side opening 104 in which filter fabric is not present. Side opening 104 is closed by a series of flaps of a suitable material, constructed to normally be closed, together with a tube 108, which may be corrugated, and which is open at its inner end 112, as shown most clearly in
Referring to
Then, in the manner described previously, for example with respect to
During implantation, sheath 120 may be placed in contact with filter 90 to stabilize the position of the filter.
After implantation, suction is maintained through tube 64 to extract debris mixed with blood and, as in the case of the embodiment of
Then, assembly 60 is withdrawn from the patient's body, filter 90 is retracted into sheath 120, and sheath 120, with retracted filter 90, is withdrawn from the patient's body.
According to an alternative valve implantation procedure, the heart may be punctured at its apex and valve assembly 60 can be inserted through the puncture opening in the apex from a location below the existing valve. In this case, the filter structure shown in
In further accordance with the invention, a wall stent or stent graft may be initially deployed to protect the aorta during valve implantation and an inflatable sheath may be employed in place of sheath 32 to facilitate retraction of filter 2, 72, 80, 90. In addition, the filter may be provided with additional structures to control blood flow from the heart in a manner to assure that the filter is not displaced by the force of the blood flow. These features will be described in detail below.
Two well known stent-grafts are: the Cook Zenith Flex graft and the Medtronics graft for the ascending aorta.
In each embodiment of the invention, the framework may be coated or impregnated with radiopaque material, or could be provided with individual radiopaque studs, or beads, lining the top and/or the bottom rings of the filter framework to facilitate guidance of the filter to its desired position and introduction of wire 62. i.e. guidance of system 66 through the hole at the top of the filter and into the existing valve.
Filters according to the present invention may be positioned to surround the entire circumference of the valve that is deployed, with the result of preventing blood clots from entering the coronary arteries.
In the case of the embodiment shown in
A further embodiment of the invention is composed of a debris filter 150, shown in
The filter shown in
The lower end of filter 150, enclosed by ring 156, is open to receive blood and debris from the region being treated, such as the heart valve region and the area of the aortic wall into which vein bypasses are customarily attached or implanted.
Filter 150 differs from filter 80 essentially only in that the upper end of filter 150, enclosed by ring 154, is covered with the same type of filter fabric as described earlier herein, with a pore size of, for example 100 μm. The upper end of filter 150 may be provided with a small diameter ring 170 secured to ring 154 by at least four radial spokes 174. The outer ends of spokes 174 are bonded to ring 154 in any suitable manner to secure ring 170 in place. Ring 170 and spokes 174 may be made of nitinol wires. Filter fabric is not present in the region enclosed by ring 170.
Ring 170 is dimensioned to receive a small diameter tube, or catheter, 176, which may have a diameter of the order of 5-6 Fr. and is preferably dimensioned to achieve a sufficiently close fit between ring 170 and tube 176 to prevent the escape of debris therebetween. Tube 176 may be of a type known as a “pigtail” catheter.
After filter 150 has been deployed at the desired location, a guidewire (not shown) is introduced, for example along the same path as filter 150, and then passed though ring 170 into the region enclosed by filter 150. Then tube 176 is passed over the guidewire and through ring 170, also into the region enclosed by filter 150.
Filter 150 is provided at its side with a plate 160 provided with a through opening 162 that is not covered with filter fabric.
Tube 176 is employed to inject a contrast fluid that facilitates visualization of the surgery site, such as the aorta and the aortic valve. It can also be utilized to work with a TAVI catheter assembly which is inserted through opening 162. Thus, the tube 176 and the TAVI catheter can be used simultaneously to permit observation of the natural valve and to cross it, respectively.
After the need to inject contrast fluid has ended, tube 176 can be pulled up so that its lower end is still within filter 150 and so that it continues to obturate the opening defined by ring 170. Tube 176 can be connected to a suction device outside the patient's body to suction debris, inevitable accompanied by blood, through tube 176. Outside of the patient's body, debris can be filtered out of the blood and the blood can be returned to the patient's circulatory system
The device shown in
A procedure according to the invention, using the devices shown in
A first guidewire is inserted along a blood vessel path to a point close to the heart valve that is to be replaced and then a sheath, such as sheath 32 shown in
Then, a second guidewire, such as guidewire 62 shown in
After the valve has been implanted, assembly 60 and guidewire 62 are removed from the patient's body.
All of the guidewires employed in the practice of all of the embodiments disclosed herein may be any commercially available guidewires intended for use in blood vessels, such as CharterTM Guidewires marketed by Navilyst Medical of Marlborough, Massachusetts.
The following table lists the blood vessel passages that can be used for introduction of each of the devices described above.
If, in the procedure described with reference to
It is important to point out that the TAVI catheter and the pigtail catheter are in proximity to each other prior to and immediately after the valve is implanted. This is an essential part of the procedure which ensures appropriate positioning during the process of implanting the valve. It is also to be noted that in either event, namely, using the subclavian or the groin, due to the constraints of space, the TAVI catheter assembly 60 and the filter enter through the same artery, with the filter sheath being withdrawn from the artery before introduction of the valve implantation assembly 60, while, the pigtail catheter is introduced through a different artery. This ensures that the diameter of the blood vessel in either case is not stretched to the point of injury.
In the case of the embodiment shown in
A further embodiment of a device incorporating a filter according to the present invention is illustrated in
The embodiment shown in
A purpose of this embodiment is to avoid the adverse, and potentially fatal, effects of bypass surgery caused by the migration of emboli into the brain, resulting in strokes and cognitive disorders.
This embodiment includes a filter 302 that will be deployed at a location downstream of the surgical site. Filter 302 is somewhat similar in form to filter 2 shown in
Large diameter end 304 may have a deployed diameter of 32-40 mm, while small diameter end 306 and tube 308 may have a diameter of the order of 4 mm
The proximal end of tube 308, i.e. the end that will be outside of the patient's body, is secured to a filter 312. The assembly composed of filter 302 and tube 308 may be introduced through a suitable sheath 320 into an artery to a point downstream of a location where debris will be produced by the surgical procedure and upstream of vessels that carry blood to the brain.
When filter 302 has been introduced to the desired location and deployed, and the surgical procedure is being performed, debris produced by the procedure will be conveyed, along with blood, into filter 302. A portion of the blood will then pass through the filter mesh, or fabric, that covers the circumference of filter 302 between ends 304 and 306 while the debris, along with some blood, will flow through small diameter end 306 and tube 308 to filter 312. In filter 312, debris will be separated from blood and the filtered blood may then be conducted into an artery or vein to be returned to the circulatory system. Filter 312 may be constructed according to principles already well known in the art.
The device shown in
Filter 302 could also be introduced on the right side of the heart in the pulmonary artery as a potential means of preventing blood clots from entering the lungs and for right heart surgery. The device could be introduced in this case through a peripheral vein.
In all cases, filter 302 would be deployed downstream from the locations where emboli would be produced during the surgical procedure.
The assembly shown in
The assemblies shown in
In all of the procedures employing filters according to the invention, any opposition to deployment and positioning of the filter can be minimized by temporarily halting or reducing the flow of blood from the aorta. This can be achieved, for example, by employing a pacemaker to produce a high pacing rate, for example of the order of 220 beats/minute.
The present invention provides the possibility of using at most two to three entry passages to completely implant and stabilize the filter, trap and withdraw debris and deploy an artificial valve. These entry points can be selected from one groin and the radial artery that leads into the subclavian to carry the pigtail catheter for introducing contrast fluid, or one groin, which carries the TAVI catheter and the sheath for implantation of the filter. In the event that the both groins are blocked and cannot be used, use can be made of one subclavian to deploy the filter and TAVI catheter and the other subclavian to introduce and advance the pigtail catheter. In either of these cases, the ability exists to perform two processes: To use the TAVI catheter and filter through a single groin or subclavian and the other to implant the pigtail catheter through the opposite groin or subclavian. In either case the ability to use the TAVI catheter with the filter depends on the ability to initially advance the filter with its sheath which encloses a guide wire, to deploy the filter and after this, to withdraw the sheath which surrounds the guidewire all the way to the origin of the point of insertion of the filter, thus, creating adequate space to advance the TAVI catheter with or without its own guide wire alongside this guidewire and to enter the orifice described in the filter.
However, the TAVI catheter can be inserted into the right groin and the filter can be inserted into the left groin or vice versa or under exceptional circumstances into the right or left subclavian. It would still be possible to use the radial artery on the right or left side to implant the pigtail catheter depending on the points of insertion of the filter and the TAVI catheter. These circumstances will depend on the recently developed 12 Fr. TAVI catheters and changes in the expansibility of the modified nitinol to create the filter. These are currently not in common use.
Filters according to the present invention can have a radial expansion ratio of 8:1. If the compressed diameter is, for example, 4.5 mm, the expanded filter can obturate the aorta with a lower ring such that it is inserted to apply pressure on the circumference of the aorta to stabilize it.
The catheter that may be a pigtail catheter can be used both for injecting contrast fluid for withdrawing debris from the filter in a safe and sterile way into an artery of the wrist, namely, the radial, which allows the observer to visually see the debris and subject it to quantitative and qualitative analysis and/or filtration. The debris can be analyzed by a cell counter such as a Coulter counter, which can enable a temporal estimation of debris production and clearance.
Relative to the use of a filter on the right side of the heart, it is possible to use a filter similar to the one described previously composed of nitinol and fabric and introduced through a sheath, which filter does not incorporate orifices, or openings, as previously described. This filter is introduced, enclosed by a sheath, through a vein which carries blood to the heart and which is located in an arm, the neck or the legs.
The sheath and filter can be introduced under fluoroscopic control into the right side of the heart, traversing one of the two main veins entering the heart and is manipulated under fluoroscopic control into the pulmonary artery which supplies the lungs. The filter is deployed in a similar manner by withdrawing the sheath and allowing it to stabilize in the pulmonary artery. Since the pulmonary artery divides into left and right branches, these arteries to the left and right lung are protected from emboli. This technique is particularly applicable in cardiac surgery for congenital heart disease to prevent blood clots from entering the lungs, which is a known complication of this type of surgery. The filter is deployed and removed using the same techniques explained above with the TAVI filter and the other described filters, namely, by pulling the filter into a sheath to close it or expressing the filter out of the sheath, to deploy it.
As shown in
The embodiment further includes a wire 516 that will be guided through sheath 512 and that carries, at its distal end, as shown in
Struts 518 and 530 are preferably made of nitinol.
The filter is constructed, similar to the filters described earlier herein, to have a radially compressed state and a radially expanded state and to automatically assume the radially expanded state when unconstrained.
In the embodiment shown in
After the medical procedure has been completed and the flow of debris has subsided, the appliance may be removed in one of the following ways:
Wire 516 will be pulled back while sheath 512 is held stationary to withdraw the filter into sheath 512, while the filter is brought to its radially compressed state with the aid of struts 530, or sheath 512 will be advanced over the filter to place the filter in its radially compressed state within sheath 512. Then, sheath 512, with the filter held therein, is withdrawn from the patient's body in the reverse direction along the insertion path; or
A slit is made in the pulmonary artery to access the filter, the filter is radially compressed and wire 515 is cut by suitable instruments, after which the filter is withdrawn through the slit in the artery. Then, sheath 512 and the remainder of wire 516 are withdrawn in the reverse direction along the insertion path.
Sheath 512 may, for example, have a diameter of 10 Fr. The proximal end of sheath 512 may be connected to a suction device 550 that helps to suction debris collected in the filter.
Suction device 550 may, in turn, be connected to an arrangement such as components 410, 412 and 414, as shown in
With respect to all embodiments of the invention, if a filter having a larger compression ratio, e.g. 16:1, is used, the filter sheath may have a correspondingly smaller diameter.
The presently disclosed embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims, rather than the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
Claims
1. A collapsible and deployable filter for blocking debris and passing blood in a blood vessel in a patient's body, said filter comprising;
- a framework of a flexible material, said framework being constructed to have a radially compressed state, in which said framework is radially compressed by radial deforming forces, and a radially expanded state; and
- a flexible filter material secured to said framework and having pores dimensioned to prevent the passage of debris therethrough while allowing the passage of blood, wherein:
- said filter has, in the radially expanded state of said framework, a generally conical or frustoconical form with a large diameter end, a small diameter end opposite to said large diameter end, and a side surface extending between said large diameter end and said small diameter end;
- said flexible filter material covers at least a major part of said side surface;
- said large diameter end is open to receive blood and debris and is dimensioned to prevent flow of blood between said large diameter end and the blood vessel wall when said framework is in the radially expanded state; and
- said filter has an opening that is free of filter material at said small diameter end or in said side surface.
2. A device for removing debris from a blood vessel, comprising:
- the filter according to claim 1; and
- a sheath having an internal diameter selected to house said filter in the radially compressed state, said sheath having a length sufficient to extend out of a patient's body when said filter is at a desired location in a blood vessel.
3. The device of claim 2, wherein said opening is at said small diameter end of said filter, and said device further comprises:
- a tube having a distal end communicating with said opening for removal of debris collected in said filter, said tube having a proximal end and having a length sufficient to enable said proximal end to extend out of a patient's body when said filter is at a desired location in the blood vessel.
4. The device of claim 3, further comprising:
- a second filter connected to said proximal end of said tube for separating debris conveyed through said tube from blood conveyed through said tube.
5. The device of claim 4, further comprising:
- a source of contrast fluid connectable to said tube.
6. The device of claim 5, further comprising a valve member installed in said tube in proximity to said proximal end of said tube, said valve member having a first operating state for placing said source of contrast fluid in fluid flow communication, through said tube, with the region enclosed by said filter and blocking flow to said second filter, and a second operating state placing the region enclosed by said filter in fluid flow communication, through said tube, with said second filter and blocking flow to and from said source of contrast fluid.
7. A procedure for removing debris from a blood vessel in a patient's body and allowing blood to pass through the blood vessel, comprising, in the order recited:
- providing the device according to claim 6;
- introducing said filter into the blood vessel;
- placing said valve member in the first operating state and passing contrast fluid from said source of contrast fluid through said tube; and
- placing said valve member in the first operating state and causing debris to flow through said tube from the region enclosed by said filter to said second filter.
8. The procedure of claim 7, further comprising passing blood that has been separated from the debris in said second filter to a second blood vessel.
9. Apparatus for removing debris from blood flowing through a blood vessel, comprising:
- the device according to claim 2; and
- a debris removal device operative to extend into the space enclosed by said filter and to conduct debris from the space enclosed by said filter to a location outside the patient's body
10. The apparatus of claim 9, further comprising an assembly for implanting a prosthetic aortic valve in the patient's heart.
11. A procedure for implanting a prosthetic aortic valve in the patient's heart while blocking flow of debris through the aorta, comprising:
- providing the apparatus of claim 10,
- inserting said filter, in its radially compressed state in said sheath, along a blood vessel path into the aorta;
- withdrawing said sheath to cause said filter to assume the radially expanded state at a desired location on the aorta;
- inserting said assembly for implanting a prosthetic aortic valve in the patient's heart into the aorta through said opening of said filter, and through said large diameter end of said filter and passed an existing heart valve;
- operating said assembly to implant the prosthetic aortic valve;
- withdrawing said assembly from the patient's body;
- conveying debris resulting from said inserting and operating steps, with debris removal device, from the region enclosed by said filter to a location outside the patient's body; and
- withdrawing said assembly from the patient's body.
12. The procedure of claim 11, further comprising supplying contrast medium to the location where the valve is implanted.
13. The procedure of claim 12, wherein the contrast medium is supplied through the debris removal device.
14. The apparatus of claim 9, wherein said opening is at said small diameter end of said filter, and said debris removal device comprises a tube having a distal end communicating with the region enclosed by said filter through said opening and dimensioned to have a proximal that extends out of the patients body when said filter is in the desired location in a blood vessel.
15. The filter of claim 1 wherein said opening is at said small diameter end of said filter.
16. The filter of claim 15, further comprising at least one control wire having a distal end connected to said framework at the small diameter end of said filter.
17. A device for removing debris from a blood vessel, comprising;
- the filter according to claim 16; and
- a sheath having an internal diameter selected to house said filter in the radially compressed state, said sheath having a length sufficient to extend out of a patient's body when said filter is at a desired location in a blood vessel.
18. The filter of claim 1 wherein said opening is in said side surface of said filter.
19. A filter for blocking debris and passing blood in a blood vessel in a patient's body, said filter having a generally conical form and comprising: a large diameter end; a small diameter end and a side surface, said filter being open at said large diameter end and being provided with an opening in small diameter end or on said side surface.
20. A device for trapping debris produced during a surgical procedure performed on a patient, said device comprising:
- a collapsible and deployable filter for blocking debris and passing blood in a blood vessel in a patient's body, a guidewire connected to said filter, and a sheath in which said filter is housed,
- said filter comprising; a framework of a flexible material, said framework being constructed to have a radially compressed state, in which said framework is radially compressed by radial deforming forces, and a radially expanded state; and a flexible filter material secured to said framework and having pores dimensioned to prevent the passage of debris therethrough while allowing the passage of blood, wherein: said filter has, in the radially expanded state of said framework, a generally conical form with a large diameter end, a closed end opposite to said large diameter end, and a side surface extending between said large diameter end and end; said flexible filter material covers the entirety of said side surface from said large diameter end to said closed end; and said large diameter end is open to receive blood and debris and is dimensioned to prevent flow of blood between said large diameter end and the blood vessel wall when said framework is in the radially expanded state;
- said sheath having a distal end and having a length and flexibility sufficient to extend through the patient's blood vessels and heart from a point outside the patient's body to the patient's pulmonary artery;
- said guidewire extending through said sheath and having a distal end connected to said closed end of said filter with said filter being oriented,
- wherein said filter is extendable from said distal end of said sheath and is movable, with the aid of said guidewire, between said radially compressed state within said sheath and said radially expanded state when said filter is extended from said distal end of said sheath, and said filter is oriented such that said large diameter end faces said distal end of said sheath when said filter is extended from said distal end of said sheath.
21. A method for blocking debris in a pulmonary artery of a patient undergoing a surgical procedure on the heart, using said device as defined in claim 20, said method comprising:
- advancing said sheath with said filter in the radially compressed state within said sheath, through a vein and the heart of the patient to bring said distal end of said sheath into the pulmonary artery of the patient;
- bringing said filter to a location in the pulmonary artery of the patient outside of said distal end of said sheath to move said filter to the radially expanded state;
- performing the surgical procedure; and
- after the surgical procedure, withdrawing said device from the patient's body.
Type: Application
Filed: Mar 15, 2013
Publication Date: Oct 31, 2013
Inventor: Anthony DON MICHAEL (Bakersfield, CA)
Application Number: 13/835,816
International Classification: A61F 2/01 (20060101); A61F 2/24 (20060101);