TRANSCATHETER DEVICE AND MINIMALLY INVASIVE METHOD FOR CONSTRICTING AND ADJUSTING BLOOD FLOW THROUGH A BLOOD VESSEL

Abstract

A pulmonary artery flow restrictor system includes a funnel shaped membrane with a proximal base and a restrictive distal opening which is stretchable to larger sizes. A self-expanding frame is attached to the proximal base of the membrane for securing the membrane within the pulmonary artery.

Claims

1. A pulmonary artery flow restrictor device for treating congenital heart disease, the device comprising: a funnel shaped membrane including: a wide area base with an opening and configured to contact the inner wall of the pulmonary artery, a narrower area distal opening resisting blood flow through the pulmonary artery to lower the blood flow rate therein, and membrane material between the wide area base opening and the narrower area distal opening forcing blood in the pulmonary artery to only flow out the narrower area distal opening; and the membrane made of an inelastic material which is irreversibly stretchable to enlarge the size of the narrower area distal opening.

2. The device of claim 1 further including a self-expanding frame associated with the funnel shaped membrane for positioning the membrane in the pulmonary artery.

3. The device of claim 2 in which the self-expanding frame is made of a shaped memory alloy.

4. The device of claim 3 in which the shaped memory alloy is Nitinol.

5. The device of claim 2 in which the self-expanding frame includes a wire bent to form a series of spaced lower apexes and a series of spaced upper apexes.

6. The device of claim 5 in which the spaced lower apexes are secured to the base of the funnel shaped membrane.

7. The device of claim 2 further including one or more flexible lines connected to the self-expanding frame for collapsing the self-expanding frame.

8. The device of claim 1 in which the wide area base opening is about 10-18 mm in diameter and the distal narrower area opening is about 0.5-6 mm in diameter.

9. The device of claim 1 in which the funnel-shaped membrane is made of a polymer.

10. The device of claim 9 in which the polymer is polytetrafluoroethylene (ePTFE).

11. The device of claim 1 in which the blood flow rate through the narrower area distal opening is about 1.5-2 L/min.

12. A method of treating congenital heart disease in infants, the method comprising: using a transcatheter device to deploy a collapsed funnel shaped membrane to the pulmonary artery of an infant or child; expanding the funnel shaped membrane in the pulmonary artery so a wide area base of the funnel shaped membrane contacts the inner wall of the artery and the membrane forces blood in the pulmonary artery to only flow out a narrower area distal opening resisting blood flow through the pulmonary artery to lower the blood flow rate therein; and as the infant grows, using a balloon catheter to expand the narrower area distal opening to increase the blood flow rate through the funnel shaped membrane.

13. The method of claim 12 in which expanding the funnel shaped membrane includes the use of a self-expanding frame associated with the funnel shaped membrane.

14. The method of claim 12 in which the self-expanding frame is made of a shaped memory alloy.

15. The method of claim 13 in which the self-expanding frame includes a wire bent to form a series of spaced lower apexes and a series of spaced upper apexes.

16. The method of claim 15 in which the spaced lower apexes are secured to the base of the funnel shaped membrane when the frame and funnel shaped membrane are deployed and expanded.

17. The method of claim 13 further including using one or more flexible lines connected to the self-expanding frame to collapse the self-expanding frame.

18. The method of claim 12 in which, when the funnel shaped membrane is expanded, the wide area base opening is about 10-18 mm in diameter and the distal narrower area opening is about 0.5-6 mm in diameter.

19. The method of claim 12 in which the funnel-shaped membrane is made of a polymer.

20. The method of claim 12 in which the blood flow rate through the narrower area distal opening is about 1.5-2 L/min when the funnel shaped membrane is expanded.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0013] Other objects, features and advantages will occur to those skilled in the art from the following description of a preferred embodiment and the accompanying drawings, in which:

[0014] FIG. 1 a schematic view showing an example of a pulmonary artery flow resistor in accordance with the invention;

[0015] FIG. 2 is a schematic view showing the resistor of FIG. 1 deployed and in place within the pulmonary artery;

[0016] FIG. 3 is a schematic view of a transcatheter device for delivery a pulmonary resistor into the pulmonary artery;

[0017] FIGS. 4A-4H are schematic views showing the delivery of the pulmonary artery flow resistor into the pulmonary artery; and

[0018] FIG. 5 is a schematic view showing another example of a pulmonary artery flow resistor.

DETAILED DESCRIPTION OF THE INVENTION

[0019] Aside from the preferred embodiment or embodiments disclosed below, this invention is capable of other embodiments and of being practiced or being carried out in various ways. Thus, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of components set forth in the following description or illustrated in the drawings. If only one embodiment is described herein, the claims hereof are not to be limited to that embodiment. Moreover, the claims hereof are not to be read restrictively unless there is clear and convincing evidence manifesting a certain exclusion, restriction, or disclaimer.

[0020] One or more embodiments of the transcatheter device and minimally invasive method for constricting and adjusting blood flow through a blood vessel of this invention provides a minimally invasive surgery (MIS) device which can be implanted within the main pulmonary artery in order to elevate flow resistance to palliate the patient's CHD symptoms and move toward systemic flow. The device includes a self-expanding metal frame or skeleton which constrains the device radially and axially attached to a balloon-expandable membrane, also referred to herein as a pulmonary artery resistor, that interacts with the blood flow and provides flow constriction. The pulmonary artery resistor facilitates MIS intervention for modification of flow resistance.

[0021] The device may be deployed minimally invasively via catheter by a cardiac surgeon. As initially configured, the pulmonary artery resistor may provide the highest level of flow resistance possible. The highest level resistance would palliate patients with the most severe CHD symptoms, such as multiple and large septal tears the highest spectrum CHD cases. However, in those cases where less restriction is desired, the surgeon may use a balloon catheter of the desired size to incrementally expand the size of the resistor in situ. An adequate sized balloon is chosen and delivered over a guidewire to a location inside the resistor. The balloon is then dilated to expand the resistor. The balloon is then deflated and finally removed. This cycle ensures that the adjustment is performed quickly since a fully expanded balloon in the middle of the main pulmonary artery (Main PA) may cause an acute spike in pulmonary pressure and stress on the heart. Evaluation of the sufficiency of the resistance change provided by the pulmonary artery resistor is obtained after the dilation balloon has performed the expansion task and is fully removed from the patient, while the guidewire and femoral introducer catheter remain in place. A surgeon may incrementally alter the resistance further by stepping up the size of the balloon and repeating the dilation procedure. The expansion cycles continue until a satisfactory pulmonary arterial pressure is reached while adequate oxygenated blood flow to the aorta is also satisfactory.

[0022] Future follow on MIS procedures to reduce resistance may be periodically necessary to maintain desired apportionment of blood flow between the lungs and the remainder of the body as the patient grows. The minimally invasive procedure to correct the flow resistance should reduce or eliminate post-surgery recovery time in an intensive care unit and hospital stay duration when compared to conventional pulmonary artery banding which requires open surgery. The pulmonary artery resistor incorporates the flow constriction geometry necessary to create the desired flow without distorting the pulmonary artery wall.

[0023] In one embodiment, the frame of the resistor may be a tubular closed or open celled lattice made out of a shape memory alloy such as nitinol. The frame may be plated in gold or other radiopaque material or alloy to improve visibility inside the vessel. The frame may include eyelets with inserted radiopaque rivets that enhance visibility for the surgeon. In one embodiment the frame preferably includes at least two crossing arms, which preferably extend beyond its tubular radius. The arms may include slots for improved adhesion to the vasculature walls. The distal ends of the arms may feature tips that have an increased surface area and a backwards bend, essentially forming feet that reduce the contact pressure against the vessel wall. The arms may be tied together in the center to prevent the frame from collapsing under high pressure.

[0024] The resistor membrane may be a 2D annular shape or an annular shape stretched along the third axis forming a conical tube or funnel. The membrane may be made of an inelastic material that retains its new shape after deformation by the balloon as described above. The material may be woven or otherwise structured in such a way that the membrane preferentially stretches in the radial direction while minimizing foreshortening. The material may be an expanded polytetrafluoroethylene (ePTFE) or similar type material. The membrane may be attached to the frame chemically such as an adhesive bond, mechanically such as stitching, hook and loop, thermal bonding or related technology. The membrane may be extruded, wrapped, or otherwise formed separately from the frame and then attached in a post process. The membrane may also be formed directly on the frame via sputtering, wrapping, or other means. The expandable membrane may be attached on the proximal side of the device such that in the conical configuration the narrow end of the funnel extends distally down the center of the frame.

[0025] The resistor may be deployed through a transcatheter procedure by which the device is collapsed between an inner guidewire lumen and outer sheath lumen. In one embodiment, there may include two or more proximally located eyelets on the frame which may extend axially beyond the main body of the frame to interact with pins, hooks, recesses, or some other attachment mechanism attached to the guidewire lumen. When the frame is collapsed inside the catheter, with such an attachment mechanism engaged, the mechanism constrains the axial and rotational motion of the frame such that any motion of the attachment device translates into corresponding motion by the frame. This link may be used for ejection of the device out the distal end of the deployment catheter, for axially repositioning or rotating a semi-deployed device, or for re-sheathing a semi-deployed device.

[0026] FIG. 1 shows an example of a pulmonary artery flow resistor 10 including funnel shaped membrane 12 and self-expanding frame 14. Membrane 12 has proximal base 16 having a wide opening 17 (e.g., with a diameter of between 10 and 18 mm) and a distal narrow opening or spout 18 (e.g., having a diameter of between 0.5 and 6 mm). Preferably, frame 14 is secured to the base 16 of the membrane. In one example, base 16 was 14 mm in diameter and restricted opening was 2 mm in diameter.

[0027] The membrane functions to resist blood flow through the pulmonary artery 20, FIG. 2 since, when the flow resistor is in place in the pulmonary artery 20, blood is restricted to only flow out distal narrow opening 18 of membrane 12 since base 16 is urged against the inner wall of the artery. Frame 14 functions to retain membrane 12 in place in the pulmonary artery. Also, using a balloon catheter, the distal narrow opening 18 of membrane 12 can be enlarged in diameter by placing a balloon catheter inside opening 18 and expanding the balloon catheter whereupon the material of the membrane in the area of opening 18 stretches via the balloon catheter and retains its new, now larger diameter, Thus, preferably, membrane 12 is made of polytetrafluoroethylene (ePTFE) or similar type polymer material typically between 0.3 thousandths of an inch and 3 thousandths of an inch thick. Other polymers may be used.

[0028] Frame 14 may be made of a shape memory alloy such as Nitinol. Frame 14 may further include inwardly bent arms 22a and 22b extending upward over membrane 12 and crossing above restricted opening 18 as shown in FIGS. 1 and 2. The arms may each extend into a branch of the pulmonary artery as shown. The arms 22a, 22b have a large surface area to reduce pressure on the pulmonary artery wall and function to anchor membrane 12 in place against the normal blood flow.

[0029] As shown in FIGS. 1-2, frame 14 is a stent like in structure and being self-expanding it expands the membrane 12 and maintains contact with pulmonary artery wall even as the pulmonary artery grows in size.

[0030] Preferably, frame 14 includes circumferential lower spaced apexes 30a, 30b, 30c and the like and upper spaced apexes 32a, 32b, 32c, and the like each between adjacent lower apexes. The lower apexes may be secured to the proximal base 16 of membrane 12. Arms 22a, 22b may include members extending from select upper apexes of the frame. So, for example, arm 22b includes member 34a extending from apex 32a and member 34b extending from adjacent apex 32b. Crossing arms 22a, 22b may be include downwardly bent distal eyelet tips 36a, 36b, respectively. Furthermore, lower apexes 30a, 30b, 30c, and the like may include eyelets 38a, 38b, and 38c, and the like, respectively. Eyelet 38a and the eyelet directly across from it may be slightly enlarged and constitute deployment eyelets which fit over deployment pins associated with a deployment device. The other eyelets (e.g., 38b, 38c, and the like) may be used to secure the frame 14 to be base of member 12. The entire frame including the arms may be formed by cutting a single thin tube of Nitinol which is then expanded on a mandrel and then heat treated so that it naturally retains this expanded shape. Radiopaque stripes 15a, 15b may be included (printed on or adhered to) on membrane 12 to enable visualization of the membrane during deployment into the pulmonary artery. Frame 14 may include a radiopaque coating to enable visualization of the frame during deployment into the pulmonary artery. In some examples, the flow resistor reduces the effective diameter of the pulmonary artery to 2 mm, a diameter which can be changed by using a balloon catheter to expand the flow resistor. The flow resistor may provide a maximum pressure drop of 40-50 mm Hg in the pulmonary artery and resist the blood flow rate to a maximum of 1.5-2 L/min. If the membrane is fully expanded, the flow resistor would produce no pressure drop and no flow rate reduction. In testing, the flow restrictor shown in FIG. 1 could be collapsed down into a 2 mm diameter package and then expanded such that base 16 and frame 14 were 13 mm-14 mm in diameter (or equal to the vessel diameter). The height of the membrane may be 8-16 mm. The frame may be 5-15 mm (from upper apex to lower apex) and the arms may be 15-30 mm long. The system may further include transcatheter device 60, FIG. 3 for delivering the membrane and the frame into the pulmonary artery. The delivery device preferably includes inner braided guide wire lumen about guide wire 65 and retractile lumen 66 (e.g., 3-5 Fr) which is retractable relative to inner lumen 62 and flared at its tip (to, e.g., 5-9 Fr) forming a garage section. The frame is releasably attached to the inner lumen, for example, by placing opposing deployment eyelets on pins 68a, 68b. Thus the frame and the membrane are collapsed and reside between lumen 66 and lumen 62. An outer support sheath 70 may also be provided. Braided guide wire lumen 62 may be thinned out just before a garage section giving maximum space between the garage section and guide wire lumen 62 in order to fit the restrictor device. The tip of the transcatheter device and the deployment pins 68a, 68b are attached to the thinned portion of guide wire lumen 62. The outer most lumen 70 serves to reduce friction for the retractile lumen 66 as it retracts relative to outer lumen 70. Outer lumen 70 terminates before the garage section giving space for the translation. The retractile sheath 66 slides along the lubricious outer lumen inner liner rather than along the vessel walls.

[0031] FIG. 4A shows catheter 60 following the guide wire 20 to the artery. In FIG. 4B the catheter continues past the valve to just beyond the split in the pulmonary artery. In FIG. 4C the lumen 66 is pulled back to reveal the arms of the restrictor frame. In FIG. 4D the lumen 66 is pulled back more until the arms begin to separate and in FIG. 4E the catheter is gradually pushed forward keeping the outer sheath back. The inner lumen 62 is then advanced, FIG. 4F until the deployment pins reach the end of the sheath and in FIG. 4G the lumen 66 is pulled back allowing the frame and the membrane to spring into position. In FIG. 4H, the catheter and the guide wire are removed leaving the flow restrictor in place.

[0032] FIG. 5 shows a design where one or more flexible lines (e.g., sutures) 80 are connected to frame 14 for collapsing the frame and removing the frame and the membrane 12 from the pulmonary artery 20. As shown in the example of FIG. 5 a suture 80a, 80b, 80c are each secured to the lower apexes 38a, 38b, 38c, respectively of frame 14 to form a web with a hook, loop, ball, knot, or other feature 82 tying the other end of all the sutures together in the center. This feature 82 may be snared by a standard transcatheter snare. Also in this embodiment, arms 22a, 22b may be flared members in a light bulb shape as shown with two or three arms intersecting in the center where they are sutured together as shown as 84. The suture keeps the arms in place and acts as a hinge allowing the arms to collapse into the outer lumen during deployment or during retrieval. The light bulb shape of the arms fit into the T of the artery. A snare may be guided through an outer lumen to grab onto feature 82 and then pulled back into the outer lumen whereupon frame 14 collapses by the force on sutures 80.

[0033] Although specific features of the invention are shown in some drawings and not in others, this is for convenience only as each feature may be combined with any or all of the other features in accordance with the invention. The words “including”, “comprising”, “having”, and “with” as used herein are to be interpreted broadly and comprehensively and are not limited to any physical interconnection. Moreover, any embodiments disclosed in the subject application are not to be taken as the only possible embodiments.

[0034] In addition, any amendment presented during the prosecution of the patent application for this patent is not a disclaimer of any claim element presented in the application as filed: those skilled in the art cannot reasonably be expected to draft a claim that would literally encompass all possible equivalents, many equivalents will be unforeseeable at the time of the amendment and are beyond a fair interpretation of what is to be surrendered (if anything), the rationale underlying the amendment may bear no more than a tangential relation to many equivalents, and/or there are many other reasons the applicant cannot be expected to describe certain insubstantial substitutes for any claim element amended.

[0035] Other embodiments will occur to those skilled in the art and are within the following claims.