Patent Description:
Current organ preservation techniques typically involve hypothermic storage of the organ in a chemical perfusate solution on ice. However, uses of conventional approaches results in injuries that increase as a function of the length of time an organ is maintained ex-vivo. These time restrictions limit the number of recipients who can be reached from a given donor site, thereby restricting the recipient pool for a harvested heart. Even within the few hour time limit, the heart may nevertheless be significantly damaged.

Effective preservation of an ex-vivo organ would also provide numerous other benefits. For instance, prolonged ex-vivo preservation would permit more careful monitoring and functional testing of the harvested organ. This would in turn allow earlier detection and potential repair of defects in the harvested organ, further reducing the likelihood of transplantation failure. The ability to perform simple repairs on the organ would also allow many organs with minor defects to be saved, whereas current transplantation techniques require them to be discarded. In addition, more effective matching between the organ and a particular recipient may be achieved, further reducing the likelihood of eventual organ rejection.

Improved ex-vivo organ care has been achieved through the use of an ex-vivo organ care system which maintains organs at physiologic or near-physiologic conditions. Not only does the system maintain the organ at physiologic temperatures, but in the case of the heart, the system maintains perfusate flow through the organ. In addition the system measures and monitors electric stimulation in the heart. The ex vivo organ care system where the heart sustained ex vivo at physiologic or near-physiologic conditions are described in <CIT> entitled "Systems for monitoring and applying electrical currents in an organ perfusion system," <CIT> entitled "Method for ex-vivo organ care and for using lactate as an indication of donor organ status," and <CIT> entitled "Compositions, methods and devices for maintaining an organ".

To maintain physiologic or near-physiologic perfusate flow through the heart, the organ must interface with the system via the aorta. This interface is achieved via an aortic cannula. Current aortic cannula designs lead to organ slippage, difficulties in maintaining a liquid tight seal, and damage to the aorta. Often these designs rely solely upon a cable tie in contact with the aorta to tighten the aorta to the aortic cannula. Depending on the size of the aorta and the size of the aortic cannula, there is a risk of laceration due to the cable ties exerting too much tension on aortic tissue, or the risk of leakage if they do not exert sufficient tension. Thus, there exists a need for an aortic cannula that is easy for health care workers to deploy, creates a tight seal with the aorta, reduces aortic slipping, and causes minimal damage to the aorta.

<CIT> relates to a cannula including a first circumferential portion, a second circumferential portion, and a seal with a first clamping surface. The first circumferential portion and the second circumferential portion are configured to mutually cooperate to support a circumference of vasculature, and form a second clamping surface. The first clamping surface and the second clamping surface are configured to cooperate to secure an end of the vasculature.

In view of the foregoing, improved devices for attaching the aorta to the system and methods of use in ex vivo organ care systems are needed.

The present invention provides an aortic cannula for use with an ex vivo organ care system. The aortic cannula comprises a cannula body which further comprises, a fitting adapted to connect to an organ care system, an aorta interface to contact an aorta, and a pivot arm comprising a pivot arm strap operably connected to a pivot mount, wherein the pivot mount allows the pivot arm strap to uniformly contact the aorta to hold the aorta on the aorta interface. In one embodiment, the pivot arm is configured such that when the pivot arm is moved toward the cannula body by rotation around the pivot mount the pivot arm strap moves away from the cannula body. In another embodiment of the aortic cannula the pivot arm and the pivot arm strap are parts of a single piece. In accordance with the invention, the aortic cannula comprises a spring which applies pressure to the pivot arm strap to hold the aorta on the aorta interface. In another embodiment of the aortic cannula a dowel pin communicates with the spring to allow the pivot arm to rotate around the dowel pin. In another embodiment of the aortic cannula the pivot arm further comprises a grip pad used to depress the top of the pivot arm. In another embodiment of the aortic cannula the grip pad is textured. In another embodiment of the aortic cannula the grip pad is removable. In another embodiment of the aortic cannula the pivot arm straps further comprise a loop and guide which retain a cable tie around the pivot arm strap. In another embodiment, the aortic cannula further comprises windows sized to normalize the compression exerted on the aorta by the cable tie such that the same amount of pressure will be exerted on the aorta regardless of the size of the pivot arm strap for a given cable tie tension. In another embodiment, the aortic cannula further comprises a connector used to reversibly secure the aortic cannula to an organ chamber. In another embodiment of the aortic cannula the connector is a threaded locking nut. In another embodiment of the aortic cannula the aorta interface is textured.

One aspect of the disclosure, which does not form part of the present invention, includes a method of using an aortic cannula to place a heart in fluid communication with an organ care system the method comprising, selecting an aortic cannula sized to fit the aorta of the heart the aortic cannula comprising, a cannula body further comprising, a fitting adapted to connect to an organ care system, an aorta interface to contact an aorta, and a pivot arm strap operably connected to a pivot mount, wherein the pivot mount allows the pivot arm strap to uniformly contact the aorta to hold the aorta on the aorta interface, depressing the pivot arm such that it rotates around the dowel pin and the pivot arm strap moves away from the cannula body, placing the cannula in the aorta, releasing the pivot arm, tightening a cable tie around the pivot arm strap to hold the aorta in place, and inserting the tapered fitting into an organ care system. In one embodiment, the method further comprises the step of suturing surgical felt pledgets on the aorta before placing the aorta on the aortic cannula.

The following figures depict illustrative embodiments of the invention.

<FIG> is a diagram depicting the aortic cannula <NUM> in one embodiment. The aortic cannula device <NUM> comprises a cannula body <NUM>, a locking nut <NUM>, and a pivot arm <NUM>. The cannula body <NUM> may contain three sub-sections, a tapered fitting <NUM>, a tapered midsection <NUM> and an aorta interface <NUM>. These subsections can be seen in <FIG> as well as in various side views of the cannula body <NUM> depicted in <FIG>. In one embodiment, the cannula body <NUM> is made from injection molded clear polycarbonate. However, one of skill in the art would understand that the cannula body can be made from other types of plastic or any other suitable material.

One of skill in the art would recognize that the while the shape of the cannula body <NUM> should be generally cylindrical, the opening need not be perfectly circular. The three sub-sections, tapered fitting <NUM>, tapered midsection <NUM>, and aorta interface <NUM>, may be of different lengths relative to one another. In addition the different subsections may be made from one piece and they may have the same diameter. One of skill in the art would also recognize that the taper angle in the sub-sections, tapered fitting <NUM>, tapered midsection <NUM>, and aorta interface <NUM>, may vary so long as the aorta interface reaches a diameter within the typical range of the diameter of an human aorta.

One end of the aortic cannula <NUM> forms tapered fitting <NUM>. The tapered fitting is sized to couple to a female connector on an organ chamber (not shown) to create a seal. A threaded locking nut <NUM>, pictured in <FIG>, is used to reversibly secure the aortic cannula <NUM> to the organ chamber (not shown). In one embodiment, the locking nut <NUM> has four wings <NUM> extending from its outer surface that are used for gripping and turning the locking nut <NUM>. In one embodiment the wings <NUM> are rectangular. One of skill in the art would understand that the wings <NUM> could be any shape or omitted. The locking nut <NUM> may have a lip protruding inward from its bottom edge that snaps over locking ridge <NUM> and into the locking groove <NUM> on the cannula body <NUM>. The locking groove <NUM> and the locking ridge <NUM> can be seen in <FIG> and <FIG>. Alternatively, the locking nut <NUM> may be secured to the cannula body <NUM> using other mechanisms known to one skilled in the art. Once the locking nut <NUM> is seated in the locking groove <NUM>, the aortic cannula <NUM> is securely fastened to the organ chamber (not shown) by turning the locking nut <NUM>. Perfusate can be perfused through the cannula into the heart without leaking. One of skill in the art would understand that other designs can be used to attach the aortic cannula <NUM> to the organ chamber to prevent leakage.

One of skill in the art would understand that the aortic cannula <NUM> can be connected to an organ care system or any other tube, device, or path of flow. In addition, one of skill in the art would appreciate that the locking nut <NUM> may be omitted in embodiments where the male-female connection between the aortic cannula <NUM> and the organ care system (not shown) is tight enough to prevent leakage. One of skill in the art would also recognize that the locking nut <NUM> could be replaced with other types of connectors generally used in the art to create a flow path between two tubes.

The tapered midsection <NUM> extends from the bottom edge of the tapered fitting <NUM> to the top edge of the aorta interface <NUM>. The tapered midsection <NUM> reaches a final diameter the size of the aorta interface <NUM>. The tapered midsection <NUM> helps to ensure smooth fluid flow from the aorta interface <NUM> to the tapered fitting <NUM>. The tapered midsection <NUM> also helps minimize air trap and hemolysis and improve hemodynamics due to the smooth transition in flow path. The tapered midsection <NUM> has a pivot mount <NUM> and a spring pocket <NUM>. The pivot mount <NUM> and the spring pocket <NUM> may be integrated with the tapered midsection <NUM>. In one embodiment, the tapered midsection <NUM> has two pivot mounts <NUM> and two spring pockets <NUM>, shown in <FIG> and <FIG>. The pivot mounts <NUM> are located on each side of the cannula body <NUM>. One of ordinary skill in the art would understand that one or more pivot mounts <NUM> and spring pockets <NUM> could be used. As shown in <FIG>, in one embodiment the pivot mount <NUM> has a circular center hole <NUM> sized to receive a dowel pin <NUM>. The spring pocket <NUM> is located on the cannula body <NUM> and provides a space for a torsional spring (not shown). The dowel pin <NUM> fits through one side of the center hole <NUM> on the integrated pivot mount <NUM>, through the center of the torsional spring in the spring pocket <NUM>, and through the other side of the center hole <NUM> on the integrated pivot mount <NUM>. The torsional spring is oriented in spring pocket <NUM> such that depressing the pivot arm compresses the spring. One end of the torsional spring rests in the spring end pocket <NUM> on the thumb pad <NUM> seen in <FIG>. One of ordinary skill in the art would understand that there are various ways to attach the pivot mount <NUM> to the cannula body <NUM> that allows the pivot mount <NUM> to pivot or move so that the aorta can be fit onto the cannula body <NUM> in operation. In one embodiment, the pivot mount <NUM> is made from injection molded polycarbonate, acetyl, or any suitable material.

One of skill in the art would also recognize that the torsional spring could be replaced with other types of spring loading mechanisms. The torsional spring could also be replaced by a molded leaf spring on the pivot arm or on the grip pad. With the use of a molded leaf spring the dowel pin would be omitted and cylindrical bosses on the cannula body <NUM> or a similar structure could be used to perform the same function.

The aorta interface <NUM> is located adjacent the tapered midsection <NUM>. The aorta interface <NUM> may be of a constant diameter and sized to fit within the aorta. The diameter of the aorta interface <NUM> can be between <NUM> and <NUM> (<NUM> and <NUM> inches). In some embodiments the diameter of the aorta interface <NUM> can be between <NUM> and <NUM> (<NUM> and <NUM> inches). Preferably, in some embodiments the diameter of the aorta interface is <NUM> (<NUM> inches), <NUM> (<NUM> inches), <NUM> (<NUM> inch), or <NUM> (<NUM> inches). The aorta interface <NUM> may be smooth or textured. <FIG> illustrates a texture <NUM> on the aorta interface <NUM> to help prevent the aorta from slipping off of the cannula body <NUM>. In the embodiment shown in <FIG>, the aortic cannula <NUM> is placed in the aorta so that the aorta does not rise above the end of the texture <NUM>. <FIG> is a cross sectional view of one embodiment of the texture <NUM>. The texture <NUM> may be of any shape. In one embodiment the texture <NUM> comprises concentric ridges extending around the aorta interface <NUM> that are sloped at a <NUM> degree angle on their lower side and are perpendicular to the cannula body <NUM> on their upper face. This design allows the aorta to slide onto the aorta interface <NUM> easily, but prevents the aorta from sliding off the aorta interface <NUM>. Preferably the ridges are about <NUM> (<NUM> inches) tall. However, one of skill in the art would understand that the texture features could be of any shape and size to allow the aorta to be situated around the aorta interface <NUM> and to help hold the aorta in place while minimizing damage to the tissue. In one embodiment, the radial edge of the aortic interface <NUM> does not have a ridge to minimize trauma to the tissue. Alternatively, one of skill in the art would recognize that a ridge could be designed to minimize tissue trauma and to hold the aorta in place.

A pivot arm <NUM> is coupled to the pivot mount <NUM>. <FIG> illustrate different views of a pivot arm and pivot arm strap (discussed below) in one embodiment. The pivot arm <NUM> allows the device <NUM> to adjust and grip aortas of different thicknesses. In one embodiment the cannula body <NUM> includes two pivot arms <NUM> coupled to two pivot mounts <NUM> on the cannula body. One of ordinary skill would understand that the number of pivot arms <NUM> corresponds to the number of pivot mounts <NUM>. The pivot arm <NUM> comprises a grip pad <NUM>, a sliding pivot window <NUM>, and a strap <NUM>. The sliding pivot window <NUM> allows the strap <NUM> to maintain uniform contact with the aorta through a range of motion. The grip pad <NUM> can be smooth, or contain features such as molded ridges or other texture to stop the user's fingers from slipping. The grip pad can be any shape, preferably round. In some embodiments the grip pad <NUM> may be detachable. In other embodiments a reusable tool that attaches to the pivot arms <NUM> could be used in place of the grip pads <NUM>. The dowel pin <NUM> allows the pivot arm <NUM> to rotate around the dowel pin <NUM> when it is actuated. The pivot arm <NUM> is made from injection molded acetyl or any material with similar properties. One of skill in the art would recognize that while the sliding pivot provides certain advantages over a fixed pivot point, a fixed pivot point could also be used. Some embodiments may include a locking mechanism to hold the pivot arm <NUM> in an open position.

The pivot arm strap <NUM> is coupled to the pivot arm <NUM>. The pivot arm strap is best seen in <FIG> and <FIG>. As shown in <FIG>, in one embodiment the cannula body <NUM> includes two pivot arm straps <NUM> coupled to two pivot arms <NUM>. One of ordinary skill would understand that the number of pivot straps <NUM> corresponds to the number of pivot arms <NUM>. The pivot arm strap <NUM> and the sliding pivot window <NUM> allow the cannula body <NUM> to uniformly grip the aorta. The pivot arm strap <NUM> is designed to be stiff enough to hold the aorta, while maintaining enough flexibility to conform to the aorta and minimize tissue damage. The pivot arm straps <NUM> are curved. The pivot arm strap <NUM> optionally has a loop <NUM> and a guide <NUM> to retain a cable tie (not shown) around the pivot arm strap <NUM>. The cable tie is made from a flexible nylon material or material with similar properties. Once the cable tie has been threaded through the loop <NUM> and slotted in the guide <NUM>, it is tightened to the desired tension. The amount that the cable tie is tightened is the same for all sizes of cannulas. Windows <NUM> in the pivot arm strap <NUM> normalize the pressure exerted on the aorta by altering the surface area of the strap in contact with the aorta. Accordingly, the size of the windows <NUM> vary depending on the size of the aorta. The size of the windows <NUM> are calculated so that when the cable tie is tightened, it exerts the same compression on the aorta for every size device <NUM>. Thus, the compression exerted on the aorta holds it in place without damaging the tissue. One of ordinary skill would understand that alternatively, the cable tie may be tightened to a specific tension for each size of the device <NUM>. In addition, other mechanisms of clamping to hold the aorta in place could be used in place of the cable tie, for example a hose clamp or a tension strap. Additionally, the pivot arm strap <NUM> and the windows <NUM> could be of different shapes and sizes. Alternatively, the windows could be omitted. One of skill in the art would also understand that the pivot arm <NUM> and the pivot arm strap <NUM> could be sections of a single piece. In addition, one of skill in the art would understand that the inner surface of the pivot arm strap <NUM> could be smooth, or textured for additional traction.

In use, the aorta is secured to the cannula body. The grip pad <NUM> is depressed by the user causing the pivot arm <NUM> to move around the sliding pivot window <NUM> and to compress torsional spring. The pivot arm <NUM> rotates around the dowel pin <NUM> in the sliding pivot window <NUM> and the pivot arm straps <NUM> move away from the cannula body <NUM>, which makes room to place the cannula in the aorta in a preferred manner than if the pivot point were fixed. When the grip pad <NUM> is released the torsional spring (not shown) exerts pressure on the pivot arm strap <NUM> and temporarily holds the aorta in place. The straps closes on the aorta and the sliding pivot window <NUM> allows the pivot point to change in order to compensate for variations in tissue thickness and maintain alignment and concentricity of pivot arm <NUM> to cannula body <NUM> through the full range of rotation. This allows the strap <NUM> to seat uniformly on the aorta. Then, the cable tie is threaded through the loop <NUM> and between the guide <NUM>. The cable tie is tightened to a predetermined tension. One of skill in the art would understand that the cable tie could be replaced with other mechanisms for securing the pivot arm straps <NUM>. In some embodiments the cable tie can come preassembled in the loops <NUM>.

The user may suture surgical felt pledgets on the aorta. The pledgets serve as an additional measure to retain the aorta on the cannula body <NUM> because the pledgets provide a barrier that does not slide between the pivot arm strap <NUM> and the cannula body <NUM>. Four sets of two (one inside, one outside) pledgets are equally spaced around the aorta and sutured. One of skill in the art will recognize that more or fewer pledgets may be used. In one embodiment, the aorta is positioned onto the cannula body <NUM> so that the pledgets are not directly above a space between the pivot arms <NUM> to prevent the pledgets from sliding through the space between the two sides of the pivot arm straps <NUM>. It will be recognized by one of skill in the art that the pledgets may be placed anywhere on the aorta and end up in any orientation with respect to the pivot arm straps. The pledgets may be standard, surgical felt pledgets. Alternatively, they may be injected molded, rigid, elastomeric pledgets made of a high Durometer material, such as silicone, or a similar material. One of skill in the art would understand that the pledgets could be replaced with other materials that attach to the tissue, and that provide an anchor to prevent the device from sliding between the strap and the cannula body or damaging the tissue. Examples of these materials include, but are not limited to, a continuous ring of material that attaches to the tissue or a staple.

<FIG> depicts a tip holder <NUM>. The tip holder <NUM> is generally cylindrical, though it may have other shapes. The tip holder has a handle <NUM>. The handle may take any shape that allows a user to hold the tip holder <NUM>. The tip holder <NUM> can also have threads <NUM>. The locking nut <NUM> can be screwed onto the threads <NUM>. The tip holder <NUM> can also have a stopper <NUM> which protrudes from the tip holder <NUM> and serves as a stopping point for the locking nut <NUM>. One of skill in the art would understand that other designs can be used to attach the locking nut to the tip holder. Alternatively, the tip holder may be secured to the aortic cannula <NUM> using other mechanisms known to one skilled in the art. Once secured, the tip holder can be used to hold the aortic cannula <NUM> with or without a heart positioned on the aortic cannula <NUM>.

Claim 1:
An aortic cannula (<NUM>) for use in an ex vivo organ care system, the aortic cannula comprising:
a cannula body (<NUM>) comprising:
a fitting (<NUM>) configured to connect to the organ care system; and
an aorta interface (<NUM>) configured to fit within an aorta;
a pivot arm (<NUM>) comprising a pivot arm strap (<NUM>), wherein the pivot arm strap is operably connected to a pivot mount (<NUM>), wherein the pivot mount is configured to allow the pivot arm strap to uniformly contact the aorta on the aorta interface; and
a spring configured to apply pressure to the pivot arm strap to hold the aorta on the aorta interface.