Patent Application
20110040241
The present invention relates generally to the field of medical devices. In particular, the invention relates to cardiac medical devices and systems for use in artificial lung (AL) and right ventricular assist device (RVAD) applications.
It is known to provide assemblies for removing blood from a patient for oxygenation and removal of carbon dioxide via an artificial lung, and/or passing blood through an artificial heart-like device such as a right ventricular assist device to support the pumping function of a failing heart. Such assemblies utilize various cannula designs to remove blood from the patient and to return blood to the patient. In particular, it is known to provide various designs of dual lumen cannulae, whereby oxygen-depleted blood is removed via the first lumen, and oxygenated blood is returned via the second lumen. Conventional cannulae for use in such blood access assemblies during extracoiporeal blood oxygenation and like procedures typically are implanted in a peripheral blood vessel such as the jugular vein.
Disadvantageously, such systems are unsuited for long term, repeated use. Rather, during use, patient mobility is restricted and at the end of a treatment session, the cannula must be removed. In the event of subsequent treatment sessions, another cannula must be implanted, requiring multiple instances of cannula implantation and removal, with associated discomfort, trauma, and potential issues of infection to the patient. Thus, there remains a need in the art for novel devices, and methods and systems incorporating them, for providing routine, repeated access to an interior of the heart for procedures such as right ventricular assist procedures, artificial lung procedures, and the like, provided over a longer time period.
Alternatively, there are situations wherein access through the heart via the chest wall is not desirable. For example, such a surgical procedure may represent an untenable risk to a particular patient. Further, there are situations wherein an extreme surgical procedure such as accessing the heart via the chest wall, while one potential option, is undesirable due to the short-term nature of the problem to be solved. As an example, in the event of left heart failure, a left heart assist device may be implanted to provide support to one or more of the left chambers of the heart. In such situations, it is common, once the problem with the left side of the heart is ameliorated, for the right side of the heart to experience failure. This tends to occur one or two days after the left heart procedure is completed. Typically, with use of an RVAD, the problem with the right side of the heart can be corrected in approximately a week. In such situations, while it is possible to open the patient's chest to install a support device such as an RVAD, the surgery is extensive and requires extended recovery time. In such situations where providing short-term assistance to the blood pumping function of the heart is needed, percutaneous access to the heart interior may be more desirable. The present disclosure provides also improved cannula designs for accomplishing this goal.
The present invention provides a system for accessing an interior of a heart, intended to allow routine repeated treatment sessions. The system of the invention comprises a selectively occludable conduit and a dual lumen cannula. In one aspect of the invention, a conduit is passed through the chest wall and through the wall of the right atrium (or other chamber) of the heart of a patient. The conduit is anastomosed to the skin of the chest wall on a first end, and to the right atrium on a second end. A closure mechanism is provided in an interior of the conduit to prevent leakage of blood. In the one embodiment, the closure is an occlusion balloon arrangement which may be deflated when the conduit is required to be open, and which may be inflated to occlude the conduit lumen and prevent blood leakage, or partially inflated to prevent leakage around an exterior of a cannula passed through the conduit.
A cannula having an introducer held within a central lumen thereof may then be passed through the conduit (with the balloon closure at least partially deflated) to introduce the cannula into the right atrium, after which the introducer may be withdrawn. Similarly, the occlusion balloon arrangement prevents leakage of blood at the site of anastomosis of the conduit to the right atrium of the heart.
In another aspect of the invention, cannulae for use with the described conduit are provided, defining a first lumen (drainage lumen) for withdrawal of blood from the patient and delivery of that blood to an extracoiporeal device, and a second lumen (infusion lumen) for delivery of blood from the extracoiporeal device. In one embodiment, the dual lumen cannula includes a selectively flexible portion for redirecting an extendable infusion sleeve of the second lumen to deliver blood or other fluids to a blood vessel. The flexible portion may be any suitably flexible polymer, or may include an element formed of a shape memory alloy material which, when subjected to a temperature change, such as by application of an electrical stimulus, by exposure to body temperature, or by exposure to a chilled fluid such as sterile saline, contracts and bends to the desired shape. This embodiment is contemplated for use in a right ventricular assist device (RVAD).
In another embodiment, the second, infusion lumen is configured for passing through a heart septum to access the interior of the left atrium, for use with an artificial lung (AL). This embodiment may be used in patients with such compromised lung function that it is necessary to bypass pulmonary circulation entirely until a suitable donor match can be found for a lung transplant.
These and other embodiments, aspects, advantages, and features of the present invention will be set forth in the description which follows, and in part will become apparent to those of ordinary skill in the art by reference to the following description of the invention and referenced drawings or by practice of the invention. The aspects, advantages, and features of the invention are realized and attained by means of the instrumentalities, procedures, and combinations particularly pointed out in the appended claims. Various patent and non-patent citations are discussed herein. Unless otherwise indicated, any such citations are specifically incorporated by reference in their entirety into the present disclosure.
The accompanying drawings incorporated in and forming a part of the specification, illustrate several aspects of the present invention, and together with the description serve to explain the principles of the invention. In the drawings:
a-d show a side cross-sectional view of a selectively occludable conduit according to the present invention (
In the following detailed description of the illustrated embodiments, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. Also, it is to be understood that other embodiments may be utilized and that process, reagent, software, and/or other changes may be made without departing from the scope of the present invention.
In one aspect, the present invention provides a system 10 (see
The system 10 of the invention further includes a dual lumen cannula 110, adapted for passing through the interior lumen 102 of the conduit 100 to provide access to an interior of a heart, or for providing percutaneous access to an interior of the heart via a blood vessel, to allow delivering a fluid into and removing a fluid from the interior of the heart. Typically, the dual lumen cannula 110 defines a first, drainage lumen 112 for for establishing fluid communication with an interior of the heart for removing a fluid from the interior of the heart, and a second, delivery lumen 116 for establishing fluid communication with an interior of the heart for delivering a fluid into the interior of the heart.
The first lumen 112 is typically manufactured to provide a desired degree of stiffness to allow passing same through the conduit 100 described above, or through a lumen of a blood vessel, without sacrificing the required degree of flexibility. Any number of materials suitable for fabricating the first lumen 112 to provide the desired combination of flexibility and stiffness are known to the skilled artisan in this field. Still further, the first lumen 112 may include a surrounding reinforcing material or an integral reinforcing material (not shown for convenience) to provide the desired degree of stiffness and to prevent kinking. Suitable reinforcing materials which may be incorporated on or within the materials from which first lumen 112 is fabricated include without limitation wire, wire mesh, reinforcing polymers, and the like.
With reference to
A translatable closure 115 (see
In the depicted embodiment, the first lumen 112 and the second lumen 116 are arranged whereby at least a portion of the second lumen 116 is disposed in an interior of the first lumen 112. The second lumen 116 may be connected to the first lumen 112 along a length thereof, whereby at least a portion of the second lumen 116 is supported by the first lumen 112 (see
A distal end of the second lumen 116 terminates a distance beyond the draining end of the first lumen 112. In one embodiment of the invention, the second lumen 116 is provided with a selectively flexible portion 120 extending beyond the draining aperture 114 of the first lumen 112. This selectively flexible portion 120 may be induced to selectively assume a predetermined angle or curvature. The skilled artisan will appreciate that any number of structures or mechanisms may be employed to provide that flexible portion 120, and such structures or mechanisms are contemplated for use herein. For example, it is known to provide a spring elbow to create a predetermined angle or curvature in a lumen of a cannula, which elbow is kept in a straightened configuration by an introducer 202 (see FIG. 2) sleeved in an interior of the cannula lumen. Upon removal of the introducer 202 from an interior of the lumen, the spring elbow assumes a predetermined shape or angle as shown in
Similarly, it is known to provide a selectively flexible spring elbow (not shown in this figure) comprising a shape memory alloy such as nickel-titanium (NiTi). When kept at a first temperature, the NiTi sleeve remains in a substantially straightened position. However, upon exposure to a temperature change, such as by an electrical stimulus, body temperature, or sterile saline at an appropriate temperature, the NiTi sleeve or segment contracts to assume the predetermined shape or angle. Such devices for providing bends or predetermined angles/curvatures in cannulae are known in the art (see, for example, U.S. Pat. No. 7,090,659). The predetermined angle is intended to alter a direction of travel of the extendable infusion sleeve 118 to a sufficient degree to deliver an end of the extendable infusion sleeve 118 into an interior of a blood vessel, allowing delivery of a fluid into that blood vessel while a fluid is removed from a different portion of the interior of the heart via the first lumen 112. This will be described in detail below.
The second lumen 116 may also include at least a portion which is fabricated at least in part from a suitable membrane material, a portion of which defines an infusion sleeve 118 for delivering a fluid such as oxygenated blood into an interior of the heart. That infusion sleeve 118 is extendable at least beyond the apertures 114 disposed at the draining end of the first lumen 112 (see
When coupled to one or more pumps and tubing as are known in this art, fluids such as oxygenated blood may be delivered through the second lumen, and fluids such as oxygen-depleted blood may be removed via the first lumen. Such operations will be described in greater detail below.
In use, the selectively occludable conduit 100 may be implanted in the chest wall of a patient (see
The above positioning of the selectively occludable conduit 100 provides an access conduit for various procedures relating to removal of fluid from and introduction of fluid into the heart 308. Typically, the fluid removed will be oxygen-depleted blood. The fluid introduced will typically be blood which has at least been oxygenated and had excess carbon dioxide removed, although other fluids are contemplated. Such procedures are well known in the medical arts.
Use of the conduit 100 and the described system 10 in one such procedure, a right ventricular assist procedure, will now be described. As is well known in the art, a right ventricular assist procedure is intended to aid the pumping action of a weakened heart right ventricle, either for shorter term support of a failing heart until a donor heart becomes available, or for longer term therapy in heart failure patients who are not candidates for heart transplant.
The dual lumen cannula 110, including an introducer 202, is inserted through lumen 102 of the selectively occludable conduit 100, with occlusion balloons 108 deflated (see
The introducer 202 is then removed (see
In another embodiment, the presently described selectively occludable conduit 100 may be used in an alternative procedure such as for artificial lung purposes. The selectively occludable conduit 100 is implanted substantially as described above. Next (see
After removal of the introducer 202 and operative connection of the dual lumen cannula 110 to one or more pumps (not shown) in the manner described above, it will be appreciated that oxygen-depleted blood may be withdrawn via first lumen 112 from the right atrium 306, and oxygenated blood may be delivered to the left atrium 702 via second lumen 116. Thus, an artificial lung function is established. In this embodiment of the dual lumen cannula 110, flexible portion 120 and extendable infusion sleeve 118 are unnecessary.
Of course, the skilled artisan will appreciate that the presently described dual lumen cannula 110 is suitable also for providing access to an interior of the heart via a percutaneous route, which as noted above may be desirable in certain situations. The depicted dual lumen cannula 110, with an atraumatic introducer 202 sleeved therein, may be advanced through an incision or puncture providing access to a jugular vein of the body, and therethrough into an interior of the heart, wherein the drainage aperture 114 of the first lumen 112 is disposed substantially at a juncture of the superior vena cava 311, die right atrium 306, the right ventricle 312, and the inferior vena cava 313. The precise positioning of the dual lumen cannula 110 may be monitored by any acceptable method, including without limitation X-ray, ultrasound, etc.
The introducer 202 is removed, and the selectively flexible portion 120 is caused to assume the predetermined angle or curvature as described above, whereby the extendable infusion sleeve 118 of second lumen 116 is disposed substantially at an opening of the pulmonary artery 314. Again, the desired positioning of the second lumen 116 may be visualized/confined by any suitable method. Passing a fluid through second lumen 116 causes tie extendable infusion sleeve 118 to extend into an interior of the pulmonary artery 314, for delivery of the fluid thereinto. This describes use of the dual lumen cannula 110 of the present invention in a right ventricular assist function, wherein the interior of the heart is accessed via a percutaneous route.
Similarly, an alternative embodiment of the dual lumen cannula 110 may be adapted for percutaneous access to an interior of the heart for an artificial lung function. The dual lumen cannula 110 having an atraumatic inducer 202 sleeved therein is passed through the jugular vein substantially as described above, with the exception that a dual lumen cannula 110 is provided having a second lumen 116 which is of sufficient length that, after the drainage opening 114 of the first lumen 112 is positioned substantially at a juncture of juncture of the superior vena cava 311, the right atrium 306, the right ventricle 312, and the inferior vena cava 313. The introducer 202 is removed, the selectively flexible portion 120 is caused to assume the predetermined angle or curvature as described, and the second lumen 116 is advanced into an interior of the left atrium 702 through an incision or puncture (not shown for convenience) traversing the atrial septum substantially as shown in
After operative connection of the dual lumen cannula 110 to one or more pumps in the manner described above, it will be appreciated that oxygen-depleted blood may be withdrawn via first lumen 112 from at least one of the superior vena cava 311, the right atrium 306, the right ventricle 312, and the inferior vena cava 313, and oxygenated blood may be delivered to the left atrium 702 via second lumen 116 and extendable infusion sleeve 118. Thus, an artificial lung function is established.
There is accordingly provided a system 110 for providing access to an interior of a patient's heart which allows repeated access for procedures such as right ventricular assist and artificial lung procedures, and which may be incorporated into devices and systems for such procedures. Unlike conventional procedures, which require repeated implantation and removal of cannulae with associated risk of pain, sepsis, and the like, the present disclosure provides a substantially permanent or semi-permanent port (selectively occludable conduit 100) which allows such access without repeated implantation and removal of cannulae, such as in a blood vessel of the patient. Thus, patient comfort and mobility are improved, and risk of complicating factors such as sepsis and the like are substantially reduced. Alternatively, in situations where percutaneous access to the heart interior is more desirable, the present disclosure provides improved cannula designs allowing such percutaneous access.
One of ordinary skill in the art will recognize that additional embodiments of the invention are also possible without departing from the teachings herein. This detailed description, and particularly the specific details of the exemplary embodiments, is given primarily for clarity of understanding, and no unnecessary limitations are to be imported, for modifications will become obvious to those skilled in the art upon reading this disclosure and may be made without departing from the spirit or scope of the invention. Relatively apparent modifications, of course, include combining the various features of one or more figures or examples with the features of one or more of other figures or examples.
