SELF-SEALING CANNULA

Abstract

The present invention discloses a self-sealing cannula and methods of its use. The self-sealing cannula can be minimally invasively placed into the heart for drawing and/or returning blood with a self-sealing function at the interface of the blood access site. The disclosed cannula can be implemented as a single lumen cannula or a double lumen cannula, which can be used with ventricular assist devices for heart support or pump-oxygenators for ECMO and respiratory support. Through a self-sealing mechanism fixed on the ventricular wall or atrial wall, a cannula body is attached to the self-sealing fixture and blood is drawn into the lumen via an external pump and returned to the circulation system through a separate cannula. In the case of the double lumen cannula embodiment, the blood will be drawn into the drainage lumen of the double lumen cannula and returned through an infusion lumen at the desired location. The present invention achieves minimally invasive insertion without surgical sutures to the heart, and allows for optimal drainage of the blood from the heart. With use of the double lumen cannula, it prevents need for multiple cannulation sites, and greatly reduces the blood recirculation. Removal of the cannula is simplified without need for suturing or insertion of a plugging member.

Claims

1. A self-sealing cannula system, comprising: a first cannula having a distal end and a proximal end; and a flexible, self-sealing closure attached to said first cannula approximately at said distal end of said first cannula, said closure comprising a hollow, elongate structure defining an open interior, wherein said first cannula is removably attached to said interior of said closure, and wherein said closure is configured to automatically seal upon removal of said first cannula from said closure.

2. The self-sealing cannula system of claim 1, wherein said self-sealing closure is expandable from a compressed state, in which an outer wall of said closure defines an elongate, hollow cylinder, into an uncompressed state, in which an outer wall of said closure defines an upper disc, a lower disc, and a generally cylindrical wall extending between said upper disc and said lower disc.

3. The self-sealing cannula system of claim 2, further comprising a removable sheath encasing said closure and at least a portion of said first cannula, said removable sheath compressing said closure into said compressed state, and wherein said closure is further configured to automatically expand from said compressed state to said uncompressed state upon removal of said sheath within a patient's body.

4. The self-sealing cannula system of claim 3, wherein said closure is temperature-responsive and further configured to expand from said compressed state to said uncompressed state in response to a patient's body temperature.

5. The self-sealing cannula system of claim 2, said hollow cylinder further comprising a first connecting member on an interior of said hollow cylinder, and said first cannula further comprising a second connecting member on an exterior of said first cannula configured for removable attachment to said first connecting member.

6. The self-sealing cannula system of claim 5, wherein said first connecting member and said second connecting member comprise a mating threaded connection.

7. The self-sealing cannula system of claim 1, wherein said closure further comprises a distal end and a proximal end, and a self-closing iris at said closure proximal end.

8. The self-sealing cannula system of claim 7, wherein said iris is configured to automatically close said closure proximal end upon removal of said first cannula from said closure.

9. The self-sealing cannula system of claim 1, further comprising: a second cannula positioned within said first cannula and extendable from said distal end of said first cannula.

10. The self-sealing cannula system of claim 9, said second cannula having a distal end formed of an expandable wire frame.

11. The self-sealing cannula system of claim 10, wherein said expandable wire frame of said second cannula is temperature responsive and configured to expand in response to a patient's body temperature.

12. The self-sealing cannula system of claim 9, further comprising a blood pump attached to said first cannula, and a blood oxygenator attached to said second cannula.

13. The self-sealing cannula system of claim 1, wherein said closure is formed of temperature responsive wire mesh.

14. The self-sealing cannula system of claim 13, wherein said wire mesh further comprises a superelastic Nitinol alloy.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The numerous advantages of the present invention may be better understood by those skilled in the art by reference to the accompanying figures in which:

[0017] FIG. 1 is a schematic view of a double lumen cannula (“DLC”) assembly placed into the right heart and pulmonary artery and including a self-sealing cannula in accordance with aspects of an embodiment of the invention.

[0018] FIG. 2A is a close-up, cross-sectional view of the self-sealing DLC of FIG. 1 and its components.

[0019] FIG. 2B is a close-up, cross-sectional view of the self-sealing DLC of FIG. 1 packaged in a sheath with two dilators and a guide catheter.

[0020] FIG. 3A is a close-up, cross-sectional view of a self-sealing single lumen cannula in accordance with further aspects of an embodiment of the invention.

[0021] FIG. 3B is a close-up, cross-sectional view of the self-sealing single lumen cannula of FIG. 3A packaged in a sheath with a dilator and a guidewire.

[0022] FIG. 4A is a schematic view of the self-sealing DLC of FIG. 1 placed into the right ventricle and pulmonary artery.

[0023] FIG. 4B is a schematic view of the self-sealing DLC of FIG. 1 placed into the left ventricle and aorta.

[0024] FIG. 4C is a schematic view of the self-sealing single lumen cannula of FIG. 3A placed into the right ventricle as a drainage cannula.

[0025] FIG. 5A is a schematic view of the DLC of FIG. 1 during dilation of the insertion site with the first dilator for placement of the infusion cannula of the self-sealing DLC into the right ventricle.

[0026] FIG. 5B is a schematic view of the DLC of FIG. 1 during dilation of the insertion site with the second dilator for placement of the drainage cannula of the self-sealing DLC into the right ventricle.

[0027] FIG. 5C is a schematic view of the DLC of FIG. 1 during its placement into the right ventricle and pulmonary artery.

[0028] FIG. 5D is a schematic view of the DLC of FIG. 1 following its placement into the right ventricle and pulmonary artery.

[0029] FIG. 5E is a schematic view of the self-seal mechanism of FIG. 1 using the double umbrella after the DLC is removed from the right ventricle.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] The invention summarized above may be better understood by referring to the following description, claims, and accompanying drawings. This description of an embodiment, set out below to enable one to practice an implementation of the invention, is not intended to limit the preferred embodiment, but to serve as a particular example thereof. Those skilled in the art should appreciate that they may readily use the conception and specific embodiments disclosed as a basis for modifying or designing other methods and systems for carrying out the same purposes of the present invention. Those skilled in the art should also realize that such equivalent assemblies do not depart from the spirit and scope of the invention in its broadest form.

[0031] FIG. 1 is a schematic view of a self-sealing cannula in accordance with aspects of an embodiment of the invention, and more particularly a self-sealing double lumen cannula (DLC) configured to draw blood from the right ventricle through the outer lumen of the DLC and to return the blood to the pulmonary artery. A double umbrella fixture serves as the sutureless self-sealing mechanism and the holder of the DLC in place on the right ventricle.

[0032] In accordance with certain aspects of an embodiment of the invention, a DLC assembly is shown in FIG. 2. The DLC assembly 1 includes a circular drainage cannula whose internal surface forms a drainage lumen 2, a side fused tubular cannula 3 whose internal surface forms the infusion lumen 4, and a compressible double umbrella 6. The infusion cannula comprises a regular thick wall infusion port 7, a thin wall circular tube 4 embedded on the sidewall of the drainage lumen, and an extended circular portion 5. A portion of the infusion cannula runs through the lumen of the drainage cannula. The extended portion 5 is a thin wall circular tube, but re-enforced with a wire frame so that it is strong in the radial direction, but flexible and conforming in the axial direction. Furthermore, a small section of the extended infusion cannula 5 comprises a naked zig-zig wireframe (as shown) so that the returned blood from the infusion lumen can be distributed axially and radially in the targeted blood vessel and the returned blood flow is not blocked when the distal tip is positioned against the vessel wall. The double umbrella 6 is attached to the drainage cannula body. The double disc-like umbrella 6 comprises a pair of outer unfolding wire mesh umbrellas 10, a metal ring 9 and an inner recoiling wire mesh iris 11 (similar in configuration to a camera iris or shutter). The wire meshes are preferably formed of a shape memory alloy that may be compressed radially to a diameter less than its intended diameter during deployment, and recover to its intended functional shape when warmed to its transformation temperature as a result of the patient's own body temperature. In an embodiment of the invention, the wire mesh of the double umbrella 6 is particularly formed from Nitinol, an alloy typically made of approximately 55%-56% nickel and 44%-45% titanium by weight. The exterior configuration of double umbrella 6 is somewhat similar to atrial and ventricular septal defect occluder devices, such as the Amplatzer occluder device available from AGA Medical Corp. of Golden Valley, Minn., but as described in greater detail herein is significantly improved to provide for its use with a cannula assembly and allowing self-sealing after removal of a cannula that extends through the double umbrella 6.

[0033] Nitinol is an alloy of nickel and titanium. Nitinol has a superelastic property, which refers to the ability of recovering to its original shape above a certain temperature (transformation temperature) after a deformation at a lower temperature. A process called shape setting is used to make Nitinol remember a desired shape. Usually, this process comprises tightly constraining the material into the desired shape on a mandrel at 450-550° C. for 10-80 minutes depending on the Nitinol material from different brands, which process is known to persons skilled in the art. In at least one embodiment, the best condition of heat treatment for the Nitinol wire (Johnson Matthey Inc., West Chester, Pa.) with a diameter of 0.01 inch in cross-section is 500° C. for 70 minutes, which can make its transformation temperature equal to 27° C. In other embodiments, the transformation temperature can be between 30° C. and 37° C. Below the transformation temperature, the material is not stable and its shape can be changed easily. Cannula assemblies incorporating Nitinol wire mesh configurations, and methods of their use and manufacture, are described in international PCT Application No. PCT/US14/46978 titled “Self-Expanding Cannula,” the specification of which is incorporated herein by reference in its entirety.

[0034] Alternatively, the wire mesh may be sufficiently flexible so as to allow it to be radially compressed (such as by inserting the wire mesh and cannula into a tearable sheath for initial insertion of the cannula into a patient's ventricle, as further described below) and thereafter return to its expanded, normal shape after such radial compression is removed. When the wire mesh is released from the sheath introducer, it can expand in the radial direction to seal the insertion site on the ventricular wall and to conform to the epicardial and endocardial walls. Similarly, the iris 11 is preferably formed of the same shape memory alloy wire mesh as the double umbrella. A metal circular ring 9 may be attached to the wire mesh to provide a lock mechanism for the drainage cannula body to be affixed to the double umbrella 6. A male thread is preferably formed on the outer circular surface of the drainage cannula. A matching female thread is preferably formed on the inner surface of the ring of the double umbrella. Thus, the DLC can be locked in place or removed from double umbrella 6 by threading in or out. The iris 11 of the double umbrella 6 functions as the self-sealing shutter, which is similar to the circular shutter of a camera. When the DLC is in use, the iris is forced to expand by the drainage cannula body. When the drainage cannula is removed, the iris recoils back to close the central hole of the double umbrella 6. The drainage cannula tip is preferably made of biocompatible metal, such as titanium, and flush-mounted on the double umbrella 6. Therefore, the drainage tip slightly extrudes from the ventricular wall to provide excellent blood drainage and prevent tissue overgrowth into the cannula lumen. The remaining portion of the cannula is made of biocompatible polymer, such as polyurethane, PVC, etc. The circular body of the drainage cannula is wire re-enforced. The metal tip and cannula body are molded and fused together. FIG. 2B shows the self-sealing DLC 1 assembled in a sheath 12 with two dilators 13 and 14 and a guide catheter 15. The double umbrella 6 and its iris 11 are compressed in the sheath 12.

[0035] Alternatively, a section of vascular graft with the pre-set purse-string suture may be sewn on the double umbrella to serve the function of the above mentioned iris to seal the central hole of the double umbrella after the cannula body is removed. When the drainage cannula body is withdrawn from the double umbrella by unlocking the thread, the double purse-string is pulled and ligated the graft lumen to seal the hole.

[0036] In accordance with certain aspects of an embodiment of the invention, a single lumen cannula assembly is shown in FIG. 3A. The self-sealing single lumen cannula comprises a circular tube 16 whose internal surface 17 forms the drainage lumen or infusion lumen and a double umbrella 19 with iris 24. The proximal end is the connector port 18. FIG. 3B shows the self-sealing single lumen cannula 16 assembled in a sheath 20 with a dilator 21 whose central hole 22 is configured for passing a guide catheter or a guidewire 23. The double umbrella 19 is compressed by the sheath 20 and the iris 24 is expanded by the cannula body in the sheath 20. In this configuration, the single lumen cannula preferably includes a threaded connection to the interior of double umbrella 19 of similar configuration to that described above with respect to the DLC.

[0037] FIG. 4A is a schematic, cross-sectional view of the DLC placed on the right ventricular wall to draw blood from the right ventricle through the drainage lumen of the DLC and to return the blood to the pulmonary artery through the infusion lumen of the DLC. The double umbrella fixture seals the insertion site on both the endocardium side and the epicardium side through the pre-formed flexible and conforming double umbrella wire mesh. The self-seal iris is expanded.

[0038] FIG. 4B is a schematic, cross-sectional view of a DLC placed on the left ventricular apex to draw blood from the left ventricle through the drainage lumen of the DLC and return the blood to the aorta through the infusion lumen of the DLC. The flexible and conforming double umbrella again is placed on the apex and seals the insertion site. The DLC is placed in the same fashion as placed in the right ventricle as described above.

[0039] FIG. 4C is a schematic, cross-sectional view of the self-sealing cannula configured as a single lumen cannula which is placed on the right ventricle wall to draw blood from the right ventricle. The same self-sealing conforming double umbrella seals the insertion site.

[0040] FIG. 5 A-E show the deployment and removal of a self-sealing DLC according to aspects of an embodiment of the invention into the right ventricle and pulmonary artery. A needle is used to punch the right ventricle for passing a guidewire. A Swan-Ganz type balloon catheter can be used to run through a central lumen of the dilator inside the infusion lumen. The balloon guide catheter with an inflatable balloon is then inserted into the right ventricle and advanced into the pulmonary artery with the aid of the inflated balloon and the guidewire. Once the guidance catheter is in place (which can be verified by fluoroscope or echocardiography), the infusion lumen cannula with its dilator is advanced into contact with the right ventricular epicardium by following the guide catheter (FIG. 5A). Through its progressive conical tip of the dilator, the needle punch site is gradually enlarged as the infusion cannula is pressed into the right ventricle and then advanced into the pulmonary artery. At this time, the second dilator for the drainage lumen is approaching the insertion site (FIG. 5B). Through the semi-conical shape of the dilator, the insertion site is further enlarged by the dilator to allow the tip of the sheath of the DLC to advance into the right ventricle (FIG. 5C). Once the first half of the compressed double umbrella is located in the right ventricle, the sheath of the DLC can be withdrawn. A tearable sheath can be used here. After the sheath is removed, the first umbrella of the double umbrella unfolds inside the right ventricle and conforms to the endocardium. The second umbrella likewise unfolds outside the right ventricle and conforms to the epicardium once the sheath is completely removed (FIG. 5D). Then the DLC is in place for connection to a VAD for mechanical circulatory support or an ECMO system for respiratory support. If the support is no longer needed, the DLC can be removed by un-threading the cannula body and withdrawing the cannula body. Once the cannula body is out of the right ventricle, the iris on the exterior portion of the double umbrella (which has been expanded by the cannula body) recoils to its pre-formed shape to seal the central opening of the double umbrella (FIG. 5E).

[0041] Similarly, a DLC having the above features can be placed into the left ventricle (FIG. 4B) using the same approach. For the single lumen cannula, only one dilator is needed. The approach described above can be easily adapted for placing the single lumen cannula (FIG. 4C). Once the DLC or the single lumen cannula is placed in the circulation system, the respective ports (drainage port and infusion port) are connected to a VAD for heart support or an ECMO system for respiratory support.

[0042] Advantages of the invention may include any of the following:

[0043] 1. Minimally invasive insertion and sutureless self-sealing of direct heart cannulation;

[0044] 2. Avoidance of multiple heart cannulation sites;

[0045] 3. Drainage unimpeded by vein and wall obstruction;

[0046] 4. Less possibility of thrombosis and flush mounted drainage tip; and

[0047] 5. Minimal blood recirculation.

[0048] Having now fully set forth the preferred embodiments and certain modifications of the concept underlying the present invention, various other embodiments as well as certain variations and modifications of the embodiments herein shown and described will obviously occur to those skilled in the art upon becoming familiar with said underlying concept. It should be understood, therefore, that the invention may be practiced otherwise than as specifically set forth herein.