Devices, methods and systems for establishing supplemental blood flow in the circulatory system

Devices, systems and methods for establishing a blood flow conduit between a chamber in a heart of a patient and a remote location. A blood inflow cannula having an outer surface and proximal and distal end portions. The distal end portion is configured for insertion into the chamber of the heart. First and second anchor elements have respective maximum width dimensions extending outwardly from the outer surface of the cannula. The first anchor element is positioned more distally than the second anchor element defining a tissue receiving space therebetween. The maximum width dimension of the first anchor element may be larger than the maximum width dimension of the second anchor element in use. The first anchor element is configured to be positioned inside the heart chamber and the second anchor element is configured to be positioned outside the heart chamber with heart tissue held in the tissue receiving space therebetween.

TECHNICAL FIELD

This invention generally relates to medical devices and methods and, more particularly, to methods and devices for fluid coupling to the heart of a patient in systems for assisting blood circulation in a patient.

BACKGROUND

Various devices and methods have been utilized to conduct blood from the heart to assist with blood circulation in a patient. This is often desirable or necessary in cases where a patient is experiencing congestive heart failure and a transplant organ has either not been located, or the patient is not a suitable candidate for a transplant. The blood pumps are typically attached directly to the left ventricle of the heart, however, at least one blood pump system locates the pump remotely, such as subcutaneously in the manner of a pacemaker. In this regard, see U.S. Pat. No. 6,530,876, the disclosure of which is hereby fully incorporated by reference herein. In this situation or similar situations, a cannula may be used to create an inflow conduit from the heart (an intra-thoracic location) to a pump located in a superficial (non-thoracic cavity) location, which may be the so-called “pacemaker pocket.” Of course, other remote locations are possible as alternatives. The pacemaker pocket is a location usually accessed by a surgical incision generally parallel to and below the collarbone extending down toward the breast, and over the pectoral muscle. Sometimes the pacemaker pocket is made below the muscle. The pump, to which the cannula is connected, is intended to sit in the pectoral pocket, and is preferably but not limited to the right side of the chest.

One area in need of improvement is the anchoring mechanism used to fluidly connect the inflow conduit or cannula to the heart. The cannula can be connected and anchored to any chamber of the heart from which it is desired to conduct or conduit blood. One anchor point is the left side of the heart, such as the left atrium. This is shown in U.S. Pat. No. 6,530,876. It would be desirable to ensure that this connection is as secure and leakage free as possible. In addition, the procedure for making the connection should be as simple as possible under the circumstances.

General cannula implantation methods known and usable in connection with the present invention may involve many different approaches and several of the representative approaches are described further below. For example, the cannula may be implanted by directly invading the thoracic cavity. Other surgical methods include so-called open heart surgery in which a median sternotomy is made to fully expose the heart within the thoracic cavity. Still other surgical methods include less invasive surgical methods such as a thoracotomy, mini-thoracotomy, thoracoscopic, or any other less invasive approaches. Any of these surgical methods can be used to implant the cannula in fluid communication with any desired location of the heart as described herein.

Alternatively, a transluminal method of implanting the cannula may be used in which the thoracic cavity is not invaded directly, but rather the heart is accessed utilizing blood vessels naturally connecting into the heart. Translumial methods include so-called transvenous delivery of the cannula to the left side of the heart via the right side of the heart to which the major veins and the more distal peripheral veins provide natural conduits through which the cannula can be delivered. In this approach, the cannula may more precisely be referred to as a catheter. Transluminal methods generally utilize indirect visualization, such as by means of contrast-dye enhanced fluoroscopy and/or ultrasonic imaging to navigate devices through the vessels of the body.

SUMMARY

Generally, and in one of many alternative aspects, the present invention provides a device for establishing a blood flow conduit between a chamber in a heart of a patient and a remote location, such as a location at which a blood pump resides away from the heart. In this regard, the term “remote,” as used herein means away from the heart but is not limited to any particular distance from the heart. The device comprises an inflow cannula having an outer surface and proximal and distal end portions (relative to a surgeon implanting the cannula). The distal end portion is configured for insertion into the chamber of the heart. First and second anchor elements having respective maximum width dimensions extend outwardly from the outer surface of the inflow cannula at its distal end portion. The first anchor element is positioned more distally than the second anchor element and a tissue receiving space is defined between the first and second anchor elements. The maximum width dimension of the first anchor element is larger than the maximum width dimension of the second anchor element in this aspect of the invention. The first anchor element is configured to be positioned inside the heart chamber and the second anchor element is configured to be positioned outside the heart chamber with heart tissue held in the tissue receiving space therebetween. As with the other devices/systems of this invention, this device may be installed in a patient through any suitable type of surgical procedure.

In another aspect of the invention, the device as generally described immediately above is implemented in a catheter based system. In this aspect, the inflow cannula is more specifically a blood inflow catheter and the inflow catheter is configured to be directed into the venous system of the patient. The inflow catheter may be received by the delivery catheter for purposes of establishing the blood inflow conduit in a minimally invasive manner.

In another aspect of the invention, the devices and systems of the present invention may further include a blood pump having an inlet and an outlet. The outlet is adapted for connection to a remote location in the circulatory system of the patient via an outflow cannula or catheter and the inlet is adapted for connection to the inflow cannula.

In another aspect, the invention provides a method of establishing blood flow from a chamber in a heart of a patient to a remote location for providing supplemental blood flow from the heart. The method may comprise inserting at least a portion of a distal end portion of an inflow cannula into the chamber of the heart. The distal end portion includes first and second anchor elements each having a maximum width dimension in a direction perpendicular to a lengthwise axis of the inflow cannula, and the first anchor element has a larger maximum width dimension than the second anchor element. The method further comprises placing the first anchor element inside the chamber and against an inside surface of tissue defining the chamber, and placing the second anchor element outside the chamber and against an outside surface of the tissue defining the chamber.

In another method performed in accordance with the inventive aspects, a distal end portion of an inflow cannula is inserted into a chamber of the heart and includes first and second anchor elements with the first anchor element being located more distally than the second anchor element, and with a tissue receiving space located between the first and second anchor elements. This method further comprises pulling the more proximally located second anchor element out of the chamber. The more proximally located second anchor element is engaged against an outside surface of tissue defining the chamber, while the first anchor element is left inside the chamber to engage an inside surface of the chamber such that the tissue is retained in the tissue receiving space and the cannula is in fluid communication with the chamber. If needed, various manners of further securing the tissue between the anchor elements may be used. One manner may be the use of one or more purse string type suture connections.

Various additional features and aspects of the embodiments and scope of the invention will be more readily appreciated upon review of the following detailed description of the illustrative embodiments taken in conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS

FIG. 1Aillustrates one of many possible general configurations of a blood circulation assist system10implanted in accordance with the inventive aspects. Devices and systems configured in accordance with the teachings herein may be implanted in any suitable surgical manner, including but not limited to those discussed generally herein.FIG. 1Ashows the system10implanted in a transvenous endoluminal manner and, in particular, illustrates an inflow cannula12passing through the venous system into the left atrium14of the heart15via the superior vena cava16and subclavian vein18. Because cannula12passes through the venous system, it is more particularly referred to herein as a catheter12. The inflow catheter12exits at a site near the clavical of the patient20. The distal end12aof the catheter12is positioned across the interatrial septum30generally at the location of the fossa ovalis such that the distal tip12aof the catheter12is within the left atrium14. Access may be made, for example, into any portion within the left side of the heart (e.g., the left atrium and/or left ventricle) to access oxygenated blood. The proximal end12bof the catheter12is coupled to the inlet32of a blood pump34. As further shown, any suitable blood pump34may be used, including those described in U.S. Pat. Nos. 6,176,848; 6,116,862; 6,942,611; and 6,623,475 or DE 10 2004 019 721.0. An outflow catheter36is connected between the outlet38of the pump34and an artery, such as the superficial axillary artery40. Blood flow therefore travels in the direction of the arrows42from the left atrium14, through the pump34, and into the patient's arterial system through the outflow catheter36.

FIG. 1A-1illustrates an alternative system configuration in which the transvenous endoluminal implantation is performed via the jugular vein50. The inflow catheter12is brought from the jugular venous exit site52along a subcutaneous tunnel formed from the pectoral pocket where the pump34is situated. While the system implantation configurations shown inFIGS. 1Aand1A-1are representative and desirable, it will be appreciated that many other implantation configurations and schemes may be implemented depending on, for example, the needs of any particular patient or desires of the surgeon.

FIGS. 1B-1Dillustrate in a sequential fashion the technique and components used to perform a transeptal puncture into the left atrium14. For this application, the procedure may start from a subclavicular pectoral cut down60similar to that used for implantation of a pacemaker. More specifically,FIG. 1Billustrates a transceptal system including a sheath or delivery catheter62and a dilator device64received in the delivery catheter62. In this method, a needle (not shown) may be initially used to puncture the interatrial septum30generally at the location of the fossa ovalis. This needle may then be exchanged for a guidewire66that is directed into the left atrium14through the dilator device64.FIG. 1Cillustrates the step of advancing the dilator64across the interatrial septum30over the guidewire66. The guidewire66is typically looped within the left atrium14to help avoid any trauma to the heart tissue by the distal tip66aof the guidewire66.FIG. 1Dillustrates the subsequent steps of advancing the transceptal sheath or delivery catheter62across the septum30(i.e., the tissue structure between the atrial chambers) and then retraction of the dilator64as illustrated by the arrow70. The dilator64is completely removed leaving behind the sheath or delivery catheter62with the distal tip62alocated in the left atrium14and the guidewire66for use during the next step of the procedure to deliver the inflow catheter12.

As shown inFIG. 1E, the inflow catheter12, which is the pump inflow catheter of the system, may be introduced over the guidewire66and through the transceptal delivery catheter or sheath62. The inflow catheter12includes first and second anchor elements80,82fixed thereto with the first anchor element80being located more distally on the inflow catheter12than the second anchor element82. In this configuration, the anchor elements80,82may be retained in a compact state during delivery through the delivery catheter or sheath62and may be expanded either selectively or automatically as they emerge from the delivery catheter62during a subsequent step or steps.

FIG. 1Fillustrates the inflow catheter12is advanced until the most distal anchor element80, that is, the first anchor element, is deployed within the left atrium14from the distal tip62aof the delivery catheter62. In this aspect, the first or distal anchor element80may automatically expand due to an expanding mechanism associated therewith or due to the characteristics of the material forming the anchor element80itself as the anchor element80emerges from the delivery catheter62. Alternatively, a mechanism may be implemented for operation by the surgeon to selectively expand one or both anchor elements80,82as desired during the procedure. As shown inFIG. 1G, both anchor elements80,82may be deployed within the left atrium14as the inflow catheter12is pushed out from the distal tip62aof the delivery catheter or sheath62. Then, as indicated by the arrow90inFIG. 1G, the inflow catheter12is pulled proximally until the second anchor element82is pulled through the aperture92created in the interatrial septum30and resides against the outside surface (relative to the left atrial chamber) of the interatrial septum30as shown inFIG. 1H. For purposes of assisting transfer of the second or proximal anchor element82across the interatrial wall or septum30and providing perceptible feedback to the surgeon, the second anchor element82may be formed with a smaller maximum width dimension than the first anchor element80. For example, anchor element80may have an expanded diameter of 14 mm while element82has an expanded diameter of 12 mm, in the case in which elements80,82are substantially circular discs. This ensures that the smaller anchor element82may noticeably pop through the aperture92in the interatrial septum30leaving the larger anchor element80as a firm stop against the opposite side of the septum30within the left atrium14. The resulting connection will generally appear as shown inFIG. 1H, although it will be appreciated that the anchor elements80,82themselves may be of various shapes, designs and configurations, and the distal end12aof the inflow catheter12may or may not extend from the first anchor element80into the left atrium14, as shown, but may instead be flush with the atrial side of the anchor element80, or otherwise configured and shaped in any suitable manner.

To complete the system, an outflow catheter36is connected to the arterial system of the patient20, such as illustrated. For example, the outflow catheter36may be connected to the axillary artery40through a suitable surgical incision and attachment procedure which may involve the use of suitable grafts and suturing96. A supplemental blood flow pump34, having an inlet32and an outlet38is coupled to the inflow and outflow catheters12,36. The inflow and/or outflow catheters12,36may first be cut to a suitable length by an appropriate sterilized cutting tool98such that the system may be more easily implanted into, for example, a pectoral pacemaker pocket without kinking of catheters12,36as illustrated inFIG. 1J.

With reference toFIG. 2, like reference numerals indicate like elements as described above.FIG. 2illustrates an alternative anchoring method in which the first and second anchor elements80,82may reside on opposite sides of the tissue in a compact state, as shown, and then be selectively enlarged to anchor against and seal against the tissue which, in this example, is again the interatrial septum30. As another alternative, the first anchor element80which resides in the left atrium14(or other location in the left side of the heart) may be expanded and seated against the inside surface of the atrium14as the second anchor element82is pulled back through the aperture92in its compact state. The second anchor element82may then be expanded against the outside surface of the septum30(relative to the left atrial chamber14). In this embodiment, as with the previous embodiment, the anchor elements80,82may or may not be differently sized.

As mentioned above, the anchor elements80,82may comprise any suitable configuration and may involve any suitable deployment method. One desirable shape is a disc-shaped element that acts as a flange extending around the outside of the blood inflow cannula12and capable of forming a fluid tight seal against the heart tissue. The material of the anchor elements80,82may be, for example, a pliable and/or resilient material such as surgical grade silicone. Alternatively, any other material(s) may be used. For example, materials may be used that promote ingrowth of tissue or that are covered by a material that promotes ingrowth of tissue. The anchor elements may be self-expandable when removed from the delivery catheter62or may be expanded by any suitable mechanism operated by the surgeon. Other restraining members aside from the delivery catheter62may be used as well to initially restrain the anchor elements80,82in compact states during delivery to the attachment or anchoring site and optionally during initial portions of the anchoring procedure.

FIG. 3Aillustrating a fully implanted circulatory assist system100in accordance with another embodiment. Again, like numerals in the drawings described below represent like elements as previously described. Specifically, this system100comprises an inflow cannula102, a blood pump104, and an outflow cannula106. The outflow cannula106may be connected to a superficial artery, such as the axillary artery40as previously described through the use of grafts (not shown) or in other suitable manners. The inflow cannula102is attached directly to an exterior wall of the heart15on the left side, such as to the left atrial wall14a, as shown. The inflow cannula102, instead of being directed through the patient's venous system, is instead directed to this exterior area of the heart15through any desired surgical approach, such as one of the approaches generally discussed below. Once implanted, the operation of the system100is similar to that described above in terms of drawing oxygenated blood from the left side of the heart15into the inflow cannula102, through the pump104, and out to the arterial system via the outflow cannula106.

More specifically referring toFIGS. 3B-3F, one illustrative procedure for connecting the inflow cannula102is shown. In this regard, an access location110such as the so-called Waterson's groove is exposed or otherwise accessed during a surgical procedure. An incision may be made with a scalpel112to expose the access location further. As shown inFIG. 3C, a small incision120is made to access the interior of the left atrium14so as to allow for the insertion of the distal end portion102aof the inflow cannula102. The distal end portion102aof the inflow cannula102includes distal and proximal anchor elements122,124similar to those previously described, however, other designs and configurations may be used instead. As shown inFIG. 3D, one or more purse string sutures130,132may be secured around the incision120in preparation for the insertion of the cannula102, or after the insertion of the cannula102. The inflow cannula102may be inserted through the incision120such that both the distal and proximal anchor elements122,124are within the left atrium14as shown inFIG. 3E. Then, as shown inFIG. 3F, the inflow cannula102is withdrawn slightly proximally (toward the surgeon) to position the proximal anchor element124outside the left atrium14but leaving the distal anchor element122within the left atrium14. At this time, the purse string suture or sutures130,132may be tightened and tied off to fully secure the tissue140between the distal and proximal anchor elements122,124to provide a fluid tight or at least substantially fluid tight seal. It will be appreciated that any other aspects of the previously described embodiment may be used in this embodiment as well, such as the use of various materials including surgical grade silicone for the inflow cannula102and anchor elements122,124, with or without tissue ingrowth material to further aide in providing a leak tight connection to the left atrial chamber.

As further shown inFIGS. 4A and 4B, the purse string suture or sutures130,132may be tightened to a degree that is adequate to provide a leak tight seal. In this regard, the tightened tissue140should at least substantially fill or gather within the gap between the distal and proximal anchor elements122,124as schematically shown inFIG. 4B. If additional gathering of tissue140is necessary, additional tissue140may be gathered with one or more additional purse string sutures.

FIG. 5illustrates the inflow cannula102in greater detail. In this embodiment, the cannula102may be approximately 10 mm in diameter, with the proximal anchor element124being 12 mm in diameter and the distal anchor element122being 14 mm in diameter. The tip dimension d1extending outwardly from the distal anchor element122is approximately 2 mm, while the thicknesses t1, t2along the longitudinal axis of the cannula102of anchor elements122,124are each approximately 2.5 mm. The distance d2between the distal and proximal anchor elements122,124is approximately 4 mm. It will be appreciated that these dimensions are representative and illustrative in nature and may be changed according to the needs of any given case or patient. The inflow cannula102, which may be constructed from surgical grade silicone, may also include reinforcements in the form of stainless steel or Nitinol coils150. It is desirable to have the inflow cannula102as flexible as possible, but still of a design that prevents kinking. In view of the flexibility of the cannula102, it may be necessary to provide stiffness to at least the distal end portion102aduring insertion through the wall of the heart at access location110(or any other desired location). This stiffness may be provided only temporarily during the insertion procedure. For example, a trocar (not shown) may be inserted temporarily through the proximal end102bof cannula102and into the distal end portion102awhile inserting the cannula102into the heart15as described herein. To retain the distal end of the trocar in the distal end102aof the cannula102, there may be a balloon-like or other expandable element associated with the trocar that engages the interior of the distal end102aduring the cannula insertion process. After the cannula102is properly positioned as described herein, the trocar could be removed and the remainder of the implantation process, such as connection of the pump104and outflow cannula106could take place. A similar process may be used during a catheterization procedure as described herein.

Below, and as representative and nonlimiting examples, various surgical approaches are more fully described.

Surgical Open Sternotomy—This approach allows full access to the heart, especially the left atrium, and allows access to several different locations where a blood inflow cannula might be attached to the heart. However, due to the highly invasive nature of this approach, less invasive implantation approaches may be more desirable to a surgeon.

Surgical Open Thoracotomy—In this surgical approach, a relatively superior and caudal thoracotomy access is used to deliver the blood inflow cannula to the left atrium where it is anchored at a location on the roof of the atrium. This location on the atrium has specific benefit because the wall of the atrium is smooth and relatively large at this location, isolating the cannula tip from other structures within the atrium.

In another suitable surgical method, a relatively lateral thoracotomy access is used to deliver the blood inflow cannula to the left atrium where it is anchored at a location on the postero-medial wall near the interatrial septum. This location is often called “Waterson's groove” as discussed above and is a common location to make a left atriotomy when performing mitral valve repair surgery. Waterson's groove is accessed surgically by dissecting the left atrium away from the right atrium at this posterior aspect, between the superior vena cava and the left pulmonary veins.

Thoracoscopic Surgery—In this surgical method, the blood inflow cannula may be implanted in a similar location as described above in that a tubular trocar may be used to access the intra-thoracic location (Waterson's groove, for example) where the cannula would be anchored through the heart wall. In this minimally or less invasive surgical method, the entire operation is performed through these relatively small tubular trocars thereby minimizing the size of the opening in the patient's chest. Typically, additional small holes are made to deliver trocars used in conjunction with the main delivery trocar to allow placement of an endoscopic camera and specialized surgical tools for grasping, cutting, suturing, cauterizing, or performing other operations on tissue. Through the main trocar, the cannula can be delivered to the same location as in the open surgical technique (i.e. Waterson's groove) but with less invasive access across the chest wall.

Transluminal—This method of implantation can, for example, involve directing the blood inflow cannula from the heart to the superficial remote pump location via a transluminal route. This transluminal route may involve passing the cannula via the axillary and/or subclavian vein, through the superior vena cava into the left atrium and then anchoring the cannula into the left atrium by passing it through the intra-atrial septum, such as through the fossa ovalis. Alternatively, the cannula might enter/exit the venous vasculature at the jugular vein. The cannula proximal end may be routed to the superficial pectoral pump location by being tunneled under the skin or chest musculature.

Over-the-Wire (Seldinger) Technique—A method for implanting the cannula, whether in surgical or transluminal approaches, is to utilize a low profile and simple “over the wire” approach often called the Seldinger technique. The Seldinger technique for percutaneously placing a catheter into the lumen of a blood vessel involves inserting a needle into the vessel across its wall, and then following with a guide wire through the needle. Once the guide wire is placed across the skin into the vessel lumen, the needle can be removed and then a suitable catheter placed over the wire into the vessel lumen. This technique minimizes trauma to the vessel wall, as often the hole across the vessel wall is gently expanded or dilated by the catheter being introduced. Another key advantage of the technique is that blood loss is minimized because control of the hole size around whatever is inserted is maintained. As an example, the transluminal cannula could be introduced into the jugular or subclavian vein after access to the vessel is obtained using the percutaneous Seldinger technique, where the cannula would be adapted to be introduced into the vessel over the guide wire. Such adaptations would include an obturator or dilator within the inner lumen of the cannula and thereby providing support and lumen size matching to facilitate dilation and blood maintenance through the puncture site. Once the cannula is introduced via the percutaneous puncture site, a surgical tunnel from the pectoral pocket location of the pump may be made up to the subcutaneous location of the veinotomy, where the exposed end of the cannula would be secured and pulled through the tunnel to the pump pocket.

Alternatively, a variation of the Seldinger technique might be utilized in the various surgical implantation approaches described above, where the cannula system would be specifically adapted to facilitate this implantation technique. Although the Seldinger technique is most commonly associated with percutaneous access to blood vessels, an adapted version of the technique utilizing a specifically adapted cannula introduction system is a highly preferred approach to surgical implantation where direct access to the heart itself is utilized. Here, for example, an atriotomy could be made by inserting a needle across the heart wall and a guide wire then placed therethrough. After removal of the needle, with bleeding controlled and minimal, the cannula system with specialized introduction obturator within can be introduced over the wire thereby maintaining many of the advantages of the so-called Seldinger technique even in a surgical approach.

While the present invention has been illustrated by a description of various illustrative embodiments and while these embodiments have been described in some detail, it is not the intention of the Applicants to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The various features of the invention may be used alone or any combinations depending on the needs and preferences of the user. However, the invention itself should only be defined by the appended claims.