Patent Description:
Certain optional features of the invention are defined in the dependent claims. The methods described herein do not form part of the invention.

The written disclosure herein describes illustrative embodiments that are nonlimiting and non-exhaustive. Reference is made to certain of such illustrative embodiments that are depicted in the figures, in which:.

Known systems, devices and methods for providing access to a region beneath a tissue layer, or more particularly, for accessing a space (e.g., the pericardial space or pericardial cavity) between a tissue layer (e.g., the parietal pericardium) and an underlying structure (e.g., the epicardium), suffer from a variety of drawbacks. In the field of cardiac medicine, for example, minimally invasive therapies for treating conditions at the heart's surface, or epicardium, have been developed or contemplated. Example treatments include epicardial ablation, left atrial appendage ligation, lead placement, and drug delivery. An important element of these procedures is safely gaining access to the pericardial space through the pericardium, which is a thin, protective, multi-layer membrane surrounding the heart. The outermost layer is the fibrous pericardium and the inner surface facing the pericardial space is a serous membrane called the parietal layer or pericardium. Opposing the parietal pericardium is another serous membrane called the visceral layer, which forms the outer surface of the epicardium. The pericardial space between the visceral and parietal layers is a thin film of serous fluid that provides lubrication. Because of its close proximity to the epicardium, creating an access port through the very thin pericardium can be difficult without injuring the underlying epicardium, heart muscles (myocardium tissue) and other structures such as blood vessels and nerves. The movement of the beating heart, breathing motions, presence of fatty surface tissue on the external surface of the fibrous pericardium, and toughness of the pericardium are some of the additional factors that can increase access difficulty.

Non-minimally invasive procedures for accessing the pericardial space are considered surgical methods and can use a thorascope to create an opening in the pericardium called a pericardial window. One accepted minimally invasive method for accessing the pericardial space between the pericardium and epicardium for purposes other than draining effusions (pericardiocentesis) involves carefully inserting a needle with fluoroscopic guidance. This procedure, which has been used for many years and is still performed at present, employs a commercially available Tuohy needle (typically <NUM> gauge or <NUM> gauge) that accommodates a standard <NUM> inch (<NUM> millimeter) guide wire. Other epicardial access procedures are performed with a <NUM> gauge micropuncture needle which, because of the much smaller diameter, is more benign to unintended heart puncture, but very difficult to use because it is less stiff and requires exchanging to a larger, more stable <NUM> inch (<NUM> millimeter) guide wire. Using either needle type requires a high degree of skill and practice, and can be very time-consuming, and therefore this procedure has not been widely adopted, limiting the use of emerging epicardial therapies.

These and other known devices and procedures suffer from a variety of drawbacks, as will be apparent from the disclosure herein. These limitations can be ameliorated or eliminated by embodiments disclosed hereafter.

The present disclosure relates generally to tissue engagement devices, systems, and methods. In particular, certain embodiments disclosed herein can be used for creating or enlarging a space between two tissue layers and, additionally, can be used to access the space.

For purposes of illustration, much of the disclosure herein pertains to creating or enlarging the pericardial space and also accessing this space. Certain devices can engage the pericardium (i.e., the parietal pericardium), which can be pulled away from the heart, or stated otherwise, away from underlying tissue (e.g., the visceral pericardium or epicardium) to expand the pericardial cavity, which may also be referred to as the pericardial space. Enlarging the pericardial space in this manner can reduce the risk of puncturing the underlying tissue (e.g., the epicardium) when a needle is advanced through the pericardium to provide access to this space. Numerous procedures can benefit from providing access to the pericardial space in this manner, such as, for example, collection of pericardial fluid, pericardial biopsy, diagnostic and therapeutic agent delivery, placement of electrical leads, electrophysiology mapping and/or ablation, angioplasty, restenosis reduction, coronary vessel stent placement, coronary vessel bypass grafting, etc. Disclosures provided herein in the context of pericardial access, however, should not be construed as limiting, as other or further embodiments can be used for engaging other tissue layers and providing access to other spaces between tissue layers in a patient.

<FIG> is a perspective view of an embodiment of a tissue engagement system <NUM>. As more fully described hereafter, the tissue engagement system <NUM> can be used to engage a tissue layer and to pierce the tissue layer to provide access to a region beneath the tissue layer. Certain embodiments can be particularly well suited for engaging and piercing tissue layers that are relatively thin and/or are closely situated to an underlying structure. For example, some embodiments are well suited for engaging and piercing the pericardium, and can be configured to do so without contacting or damaging the underlying epicardium. Other features and advantages of various embodiments will be apparent from the disclosure that follows.

In the illustrated embodiment, the tissue engagement system <NUM> includes a tunneling system <NUM> and a tissue engagement system <NUM>. Stated otherwise, each of the tunneling system <NUM> and the tissue engagement system <NUM> is a subset of the tissue engagement system <NUM>. In the illustrated embodiment, a tunneler cannula <NUM> is common to both the tunneling system <NUM> and the tissue engagement system <NUM>. That is, the tunneler cannula <NUM> can be used with the tunneling system <NUM> to tunnel a path to a target tissue layer, and can further be used with the tissue engagement system <NUM> in the subsequent engagement and piercing of the target tissue layer.

In addition to the tunneler cannula <NUM>, the tunneling system <NUM> includes an obturator <NUM>, and the tunneling system <NUM> includes a tissue engagement device <NUM>. In the illustrated embodiment, each of the obturator <NUM> and the tissue engagement device <NUM> is configured to be selectively coupled with the tunneler cannula <NUM>.

In some embodiments, the tissue engagement system <NUM> is provided as a kit <NUM>. For example, the tunneler cannula <NUM>, the obturator <NUM>, and the tissue engagement device <NUM> can be assembled as a set and distributed together, such as in unitary sterile packaging. In other embodiments, the kit <NUM> may exclude one or more of the obturator <NUM> or the tunneler cannula <NUM>. In other instances, one or more of the tunneler cannula <NUM>, the obturator <NUM>, or the tissue engagement device <NUM> can be distributed separately.

With reference to <FIG>, the tunneling system <NUM> is shown in greater detail In the illustrated embodiment, the tunneler cannula <NUM> includes a cannula, shaft, or tube <NUM> that defines a lumen <NUM>.

The tunneler cannula <NUM> can further include a connector <NUM> at a proximal end of the tube <NUM>. The connector <NUM> can be of any suitable variety and can be configured to selectively couple/decouple the tunneler cannula <NUM> to/from the obturator <NUM>. In the illustrated embodiment, the connector <NUM> comprises a female snap fitting <NUM> that includes two resilient prongs 115a, 115b that are configured to flex outwardly relative to a longitudinal axis of the tunneler cannula <NUM>. A proximal end of each resilient prong 115a, 115b includes an inwardly directed ridge <NUM> that can engage a complementary portion of the obturator <NUM>. The illustrated snap fitting <NUM> includes a pair of diametrically opposed channels <NUM> (only one of which is shown in <FIG>). The channels <NUM> can facilitate flexion of the prongs 115a, 115b. In some embodiments, the tunneler cannula <NUM> can include one or more depth markings <NUM> of any suitable variety.

The illustrated obturator <NUM> includes a rod <NUM> that is sized to substantially fill the lumen <NUM> of the tunneler cannula <NUM>. For example, an outer diameter of the rod <NUM> can be slightly smaller than an inner diameter of the tube <NUM> to permit the obturator <NUM> to be readily inserted into and removed from the tube <NUM>, while still filling the lumen <NUM> to prevent coring thereby as the tube <NUM> is advanced through tissue (e.g., soft or connective tissue) of a patient.

As used herein, the term "diameter" is used in its broadest sense, and includes the definition of a straight line from one side of something to the other side that passes through the center point, or the distance through the center of something from one side to the other. That is, the term diameter does not necessarily imply a circular configuration. Although the drawings generally depict circular or cylindrical symmetries, such as for the tube <NUM> and the rod <NUM>, the present disclosure contemplates non-circular configurations. For example, various embodiments can have non-circular cross-sectional profiles such as triangular, rectangular, polygonal, oval, etc. Unless otherwise specified, the term "diameter" refers to the maximum diameter of a given feature, or portion thereof, as will be apparent from context.

The obturator <NUM> can include a dull or blunt tip <NUM> that may be rounded at a distal end thereof. The tip <NUM> may have a sufficiently steep pitch (e.g., be sufficiently sharp) to permit the obturator <NUM> to be readily advanced through tissue. In some embodiments, the tip <NUM> is, nevertheless, sufficiently blunt to prevent inadvertent puncturing or perforation of a target tissue layer when the tip <NUM> presses against the target tissue layer. For example, in some embodiments, the tip <NUM> may be readily advanced through tissue of a patient toward the heart of the patient (e.g., by application of about <NUM> or <NUM> pounds (<NUM> or <NUM>) of force), but when the tip <NUM> comes into contact with the heart (e.g., the pericardium) with the same amount of force, the tip <NUM> is stopped thereby and does not puncture the heart.

The obturator <NUM> can include a connector <NUM> that is configured to be selectively coupled with the connector <NUM> of the tunneler cannula <NUM>. The illustrated connector <NUM> is a male snap fitting <NUM> that is complementary to the female snap fitting <NUM> of the tunneler cannula <NUM>. The snap fitting <NUM> includes an inclined or camming surface <NUM> that spreads apart the prongs 115a, 115b until the ridges <NUM> are received into a groove <NUM> at a proximal end of the camming surface <NUM>. Any other suitable connection interface between the obturator <NUM> and the tunneler cannula <NUM> is contemplated.

In the illustrated embodiment, the obturator <NUM> includes a pair of diametrically opposed ridges <NUM>, which may act as grips that can permit ready twisting of the tunneling system <NUM> during a tunneling event. The obturator <NUM> can include an enlarged base <NUM>, which may be substantially flat, which may facilitate application of distally directed force to the tunneling system <NUM> during a tunneling event.

With reference to <FIG>, the tissue engagement device <NUM> can include coupling features similar or identical to those of the obturator <NUM>. For example, in the illustrated embodiment, the tissue engagement device <NUM> includes a connector <NUM> having a camming surface <NUM> and a groove <NUM> that are the same as like-numbered, like-named features of the obturator. Accordingly, after a tunneling event, the obturator <NUM> can be readily removed from the tunneler cannula <NUM> and replaced with the tissue engagement device <NUM>.

The tissue engagement device <NUM> can include an elongated housing or sheath <NUM> that defines a lumen <NUM>. In order to diminish the profile of a distal portion of the tissue engagement system <NUM> that is inserted in a patient, the sheath <NUM> can have an outer diameter that is slightly smaller than an inner diameter of the tube <NUM>. Such an arrangement can permit the sheath <NUM> to be readily inserted into and removed from the tube <NUM>, while providing a large amount of space for components of the tissue engagement device <NUM> that are housed within the sheath <NUM>. In various embodiments, an outer diameter of the sheath <NUM> can be no greater than about <NUM>, <NUM>, or <NUM> inches (<NUM>, <NUM>, or <NUM> millimeters). In some embodiments, the outer diameter of the sheath <NUM> is about <NUM> inches (<NUM> millimeters).

A thickness of a sidewall of the sheath <NUM> may also be selected to provide the sheath <NUM> with sufficient stiffness or rigidity to resist bending, while being narrow to provide a large amount of space for the components housed within the sheath <NUM>. In various embodiments, the thickness of the sidewall of the sheath <NUM> is no greater than about <NUM>, <NUM>, or <NUM> inches (<NUM>, <NUM>, <NUM> millimeters).

The sheath <NUM> may be formed of any suitable material. In some embodiments, the sheath <NUM> comprises stainless steel.

The tissue engagement device <NUM> can include an actuation mechanism <NUM> that can include an actuation interface <NUM> via which a user can deploy a portion of the tissue engagement device <NUM>. In the illustrated embodiment, the actuation interface <NUM> comprises a button that can be pushed distally to actuate engagement arms or pulled proximally to retract the engagement arms after actuation, as further discussed below. The actuation mechanism <NUM> can further include an access assembly <NUM>, which can be used to deploy an access device, such as a needle. In the illustrated embodiment, the access assembly <NUM> can be pushed distally to deploy the needle and can be pulled proximally to retract the needle after deployment, as discussed further below.

With reference to <FIG>, the actuation mechanism <NUM> of the tissue engagement device <NUM> can include a housing <NUM> within which various components are received. In the illustrated embodiment, the housing <NUM> includes an upper shell <NUM> and a lower shell <NUM>. The upper and lower shells <NUM>, <NUM> can be secured to each other in any suitable fashion, including one or more of friction-fit engagement, snap-fit engagement, adhesive, welding (e.g., ultrasonic welding), etc..

Use of directional terms herein, such as "upper" and "lower," are generally relative to the orientations depicted in the drawings. Such directional terms are not necessarily intended to limit the possible orientations of the devices or components. For example, in some instances, a user may prefer to orient the upper shell <NUM> downwardly, and the lower shell upwardly <NUM>, during use of the actuation mechanism.

In some embodiments, the assembled housing <NUM> can be sized to fit within the curvature of one or more curled, clenched, or gripped fingers of a user's hand. For example, an external width of the assembled housing <NUM> can be no greater than about <NUM>/<NUM> inch, <NUM>/<NUM> inch, <NUM>/<NUM> inch, <NUM> inch, or <NUM> inches (<NUM>, <NUM>, <NUM>, <NUM>, or <NUM> centimeters). In some embodiments, the width is about <NUM>/<NUM> inches. In some embodiments, an external length of the assembled housing <NUM> can simultaneously contact up to <NUM> or up to <NUM> curled, clenched, or gripped fingers of one of a user's hands. Such a configuration can provide the user with a firm handle on the housing <NUM> and can permit stable, reliable, and/or ergonomic usage of the engagement device <NUM>. In various embodiments, a gripping region of the assembled housing (e.g., the substantially parallepiped central portion of the illustrated embodiment) can have a length that is no greater than about <NUM>, <NUM>, or <NUM> inches (<NUM>, <NUM>, or <NUM> centimeters). In some embodiments, the length is about <NUM> inches.

As further discussed hereafter, the actuation interface <NUM> can be movably coupled with the housing <NUM>. For example, in the illustrated embodiment, the actuation interface <NUM> can be configured to be selectively translated distally (for actuation) or proximally (for retraction). A location of the actuation interface <NUM> relative to the housing <NUM> can be ergonomically designed for ease of use. In the illustrated embodiment, the actuation interface <NUM> is configured to pass substantially through a center point of an upper surface of the upper shell <NUM>. The actuation interface <NUM> may further be configured to move approximately equal distances from the center point in each of the distal and proximal directions. Other suitable configurations are also contemplated. The actuation interface <NUM> may be conveniently located for single-handed operation thereof. For example, in the illustrated embodiment, the housing can be gripped by multiple fingers of one hand of a user and the actuation interface <NUM> can be controlled by the thumb of that hand.

The lower shell <NUM> of the housing <NUM> can define the connector <NUM>. In the illustrated embodiment, the sheath <NUM> is fixedly secured to the connector <NUM> in any suitable manner. An engagement element <NUM> can be received within the lumen <NUM> of the sheath <NUM>, and may be fixedly secured to the connector <NUM> and/or the sheath <NUM>. Stated otherwise, the engagement element <NUM> can be fixed relative to the sheath <NUM> and/or relative to the housing <NUM>. In the illustrated embodiment, a proximal end of the engagement element <NUM> is attached to a proximal end of the sheath <NUM>.

4B depicts a distal portion of the engagement element <NUM> in greater detail. The engagement element <NUM> comprises a base <NUM>, which defines the proximal portion of the engagement element <NUM>. In the illustrated embodiment, the base <NUM> is a substantially tubular or cannular structure, and thus the base <NUM> may also be referred to as a cannular base. The cannular base <NUM> defines a lumen <NUM>. In the illustrated embodiment, an outer diameter of the base is slightly smaller than an inner diameter of the sheath <NUM>.

In the illustrated embodiment, a plurality of flexible arms 108a, 108b extend distally from a distal end of the base <NUM>. The arms 108a, 108b may also be referred to as tines or prongs. As further discussed below, the arms 108a, 108b may be integrally connected to the base <NUM>, in some embodiments, or stated otherwise, the base <NUM> and the arms 108a, 108b may be integrally formed from a unitary piece of material. For example, the arms 108a, 108b may be formed by cutting away (e.g., laser cutting) portions of a tube (see <FIG>) and then bending the remaining protrusions. In some embodiments, prior to insertion of the engagement element <NUM> into the sheath <NUM>, the arms 108a, 108b may retain a bent configuration that extends transversely outward beyond an outer perimeter of the base <NUM>, such as, for example, the configuration depicted in <FIG> and <FIG>.

Each arm 108a, 108b can include a tissue engaging member 109a, 109b that can embed within, pierce, or otherwise attach to a target tissue layer. The tissue engaging members can each include a pointed element, such as an angled end, spike, or barb, that can pierce into the target tissue layer. In the illustrated embodiment, each tissue engaging member 109a, 109b includes an angled distal end of the respective arm 108a, 108b.

With reference again to <FIG>, the engagement device <NUM> can include an actuation member <NUM> that communicates movement of the actuation interface <NUM> at a proximal end thereof to a distal end of the actuation member <NUM>. As further discussed below, the actuation member <NUM> can be configured to deploy the arms 108a, 108b of the engagement element <NUM>. In some embodiments, such as that illustrated in <FIG>, the actuation member <NUM> comprises a tube or cannula. Accordingly, the actuation member <NUM> may also be referred to as an actuation cannula.

Further, the illustrated embodiment includes a piercing member or access device <NUM> that is configured to create an access opening through the target tissue layer when deployed. In the illustrated embodiment, the access device <NUM> is a needle. Any suitable needle or other piercing member may be used. The actuation member <NUM> can be positioned within the lumen <NUM> of the sheath <NUM>, and can be sized to slide or otherwise translate freely therein. The access device <NUM> can be positioned within the lumen <NUM> of the actuation member <NUM>, and can be sized to slide or otherwise translate freely therein.

The actuation mechanism <NUM> can include multiple components that are configured to constrain operation of the tissue engagement device <NUM>. In particular, in the illustrated embodiment, the actuation mechanism <NUM> includes components that control the movement of the actuation member <NUM> relative to the engagement element <NUM>, and also relative to the access device <NUM>. Further, the actuation mechanism <NUM> includes components control the movement of the access device <NUM> relative to the actuation member <NUM> and the engagement element <NUM>. In the illustrated embodiment, the actuation mechanism includes a gate <NUM> that is received within the lower shell <NUM> of the housing, a shuttle <NUM> that is coupled with the actuation member <NUM>, and a hub <NUM> that is coupled with the access device <NUM>. At least a portion of each of these components is positioned within the housing <NUM>. Various features of these components and their functions are discussed further below with respect to <FIG>. The access assembly <NUM> includes the hub <NUM> and the access device <NUM>. The actuation interface <NUM>, the shuttle <NUM>, and the actuation member <NUM> may be referred to collectively herein as an actuation assembly <NUM>.

<FIG> depict the tissue engagement system <NUM> in various operational states, which can correspond with method steps for using the system <NUM>. These figures depict a distal end of the assembled engagement system <NUM>. Although illustrative examples for achieving the operational states depicted in <FIG> can be achieve via the illustrated actuation mechanism <NUM>, as described further below with respect to <FIG>, it should be understood that any suitable systems and methods for achieving the operational states discussed are contemplated.

<FIG> depicts a distal portion of the tissue engagement device <NUM> positioned within a distal portion of the tunneler cannula <NUM>. The tube <NUM> of the tunneler cannula is shown as the outermost tube. The outer surfaces of the sheath <NUM>, the cannular base <NUM>, the actuation member <NUM>, and the access device <NUM> are depicted in broken lines. This view depicts the compact configuration achieved by the nested, telescopic, or coaxial arrangement of the tube <NUM>, the sheath <NUM>, the cannular base <NUM>, the actuation member <NUM>, and the access device <NUM>.

The arms 108a, 108b and the tissue engaging members 109a, 109b are also identified in <FIG>. In this operational configuration of the tissue engagement system <NUM>, the tissue engagement device <NUM> may either be in the process of being advanced distally toward or through a distal end of the tube <NUM> or retracted proximally through the tube <NUM>. In either case, the pointed ends of the tissue engaging members 109a, 109b are at an interior of the tube <NUM>, or stated otherwise, are within the lumen <NUM>. In this arrangement, the pointed ends cannot inadvertently contact tissue (i.e., tissue at an exterior of the tube <NUM>) during advancement through the tube <NUM> or retraction through the tube <NUM>.

<FIG> depicts the distal end of the tissue engagement device <NUM> advanced past a distal end of the tube <NUM> of the tunneler cannula <NUM>. As with <FIG>, the tissue engagement device <NUM> is depicted in a fully retracted or unactuated state. In the fully retracted state, neither the arms 108a, 108b nor the access device <NUM> is deployed. The illustrated configuration can represent a point in time after the system <NUM> has been advanced to the target tissue layer and just before deployment of the arms 108a, 108b.

In the illustrated embodiment, the engaging members 109a, 109b of the arms 108a, 108b are positioned slightly external to a distal end of the sheath <NUM> when the tissue engagement device <NUM> is in the fully retracted configuration. Stated otherwise, the engaging members 109a, 109b are positioned distally relative to a distal end of the sheath <NUM>. The exposed pointed tips of the engaging members 109a, 109b may readily engage a target tissue layer upon contact therewith as the distal end of the sheath <NUM> is advanced into contact with the target tissue layer. Indeed, in the illustrated embodiment, the pointed tips are directed in a slightly distal direction, such that initial contact of the pointed tips with the target tissue layer as the engagement device <NUM> is advanced distally through the tunneler cannula <NUM> can urge the pointed tips into the target tissue layer. Further, due to the slight exposure of the pointed tips past the distal end of the sheath <NUM>, abutting contact of the distal end of the sheath <NUM> against the target tissue layer can provide tactile feedback to the user that the tissue layer has been initially engaged and that deployment of the arms 108a, 108b can proceed.

Although the engaging members 109a, 109b in the illustrated embodiment extend in a longitudinal direction, or distally, beyond the distal tip of the sheath <NUM>, the engaging members 109a, 109b are nevertheless restrained to a low-profile configuration in which they either do not extend or do not significantly extend laterally outward beyond a perimeter of the sheath <NUM>. For example, if the arrangement depicted in <FIG> were shown in an end-on view (directed proximally), similar to the view depicted in <FIG> and <FIG>, the full perimeter of the distal end of the sheath <NUM> would be visible in situations where the engaging members 109a, 109b do not extend laterally outward beyond the perimeter. In this view, the engaging members 109a, 109b would appear to be interior to the perimeter. Stated otherwise, if an outer surface of the sheath <NUM> were projected distally beyond the distal end of the sheath <NUM>, either all or substantially all (e.g., no less than <NUM> percent) of the engaging members 109a, 109b would be encompassed or circumscribed thereby. Such an arrangement can inhibit or avoid interaction (e.g., snagging, tearing, etc.) between the engaging members 109a, 109b and tissue that is positioned outside the perimeter of the sheath <NUM>. This can be advantageous either during deployment of the tissue engagement device <NUM> beyond the distal end of the tunneler cannula <NUM> or during retraction of the engagement device <NUM> into the tunneler cannula <NUM>.

The remainder of the arms 108a, 108b are positioned within the lumen <NUM> of the sheath <NUM>. As discussed further below, and as depicted in <FIG>, the arms 108a, 108b cross each other at a position that is within the lumen <NUM> and that is distal to a distal end of the actuation member <NUM>.

<FIG> depicts the tissue engagement system <NUM> after the arms 108a, 108b have been deployed. In particular, the actuation member <NUM> has been advanced distally beyond the position at which the arms 108a, 108b crossed each other, thereby uncrossing the arms 108a, 108b and deforming them from the undeployed configuration depicted in <FIG>. The actuation member <NUM> has forced a proximal portion of the arms 108a, 108b into an annular region between an outer surface of the actuation member <NUM> and an inner surface of the sheath <NUM>.

In the illustrated embodiment, the arms 108a, 108b are at diametrically opposite sides of the device <NUM> (e.g., at opposite sides of the cannular base <NUM>). As further discussed below, deployment of the arms 108a, 108b moves the engaging members 109a, 109b in substantially opposite directions. The engaging members 109a, 109b thus can embed within and/or apply tension to the target tissue layer in substantially opposite directions. The arms 108a, 108b are in a high-profile configuration in which they extend laterally outwardly beyond a perimeter of the sheath <NUM>.

In the illustrated configuration, the tissue engagement device <NUM> is in a partially deployed state, in that the arms 108a, 108b are deployed, but the access device <NUM> remains retracted. Deployment of the arms 108a, 108b clears the engaging members 109a, 109b away from the distal end of the actuation member <NUM> to provide an unobstructed passageway for deployment of the access device <NUM>. Stated otherwise, in the configuration depicted in <FIG>, the arms 108a, 108b cover a distal end of the actuation member <NUM>. Deployment of the arms 108a, 108b effectively uncovers the distal end of the actuation member <NUM> to provide an access pathway for the access device <NUM>.

As used herein, the term "cover" does not require direct contact against a surface (e.g., the distal end of the actuation member <NUM>), although such an arrangement is subsumed within this term. The term "cover" is used more broadly herein, and includes situations of obstruction without direct contact. For example, if the arrangement depicted in <FIG> were shown in an end-on view (directed proximally), similar to the view depicted in <FIG>, rather than perspective, much of the opening in the distal end of the actuation member <NUM> would be obstructed from view by the arms 108a, 108b. Of more pertinence, viewed in the opposite direction-namely, from the perspective of the distal end of the access device <NUM>, the distal opening of the actuation member <NUM> would appear to be obstructed. Stated otherwise, if an inner surface of the actuation member <NUM> that defines the distal opening of the actuation member <NUM> were projected distally beyond the distal end of the actuation member <NUM>, the arms 108a, 108b would be encompassed or circumscribed thereby.

In some embodiments, the actuation mechanism <NUM> can prevent deployment of the access device <NUM> prior to deployment of the arms 108a, 108b via the actuation member <NUM>. This can be a safety measure to ensure that the user does not inadvertently partially deploy the arms 108a, 108b by moving the access device <NUM> distally past the arms. That is, because the outer diameter of the access device <NUM> is only slightly smaller than the outer diameter of the actuation member <NUM>, deployment of the access device <NUM> prior to deployment of the actuation member <NUM> could extend the engaging members 109a, 109b laterally outwardly to a relatively high-profile configuration, though potentially not quite as wide or as high-profile an arrangement as can be achieved by deployment of the actuation member <NUM>.

<FIG> depicts the tissue engagement device <NUM> in a fully deployed state. In particular, the engagement arms 108a, 108b are deployed and the access device <NUM> is also deployed. The access device <NUM> has been advanced distally through the actuation member <NUM> and beyond the distal end thereof.

In some embodiments, the actuation mechanism <NUM> can prevent the actuation member <NUM> from retracting the engagement arms 108a, 108b unless the access device <NUM> is first retracted. This can serve as a safety precaution, as retraction of the actuation member <NUM> without first retracting the access device <NUM> could leave the arms 108a, 108b in a partially deployed state. For example, in the illustrated embodiment, the access device <NUM> has an outer diameter that is slightly smaller than an outer diameter of the actuation member <NUM>. Thus, if the actuation member <NUM> were to be withdrawn while the access device <NUM> is in the deployed state, the resilient arms 108a, 108b would begin to return to the low-profile configuration upon retraction of the actuation member <NUM>, but would be prevented from reaching this configuration by instead coming into contact with the outer surface of the access device <NUM>. The user could potentially think that the arms 108a, 108b had been fully retracted at this stage, due to the retraction of the actuation member <NUM>, and could withdraw the tissue engagement device <NUM> with the arms 108a, 108b in the partially deployed state. Distal movement of the tissue engagement device <NUM> in this state could potentially damage the target tissue layer, overlying tissue, and/or the engagement device <NUM> itself.

In certain embodiments, a method of retracting the system <NUM> from a patient can follow the stages depicted in <FIG> in reverse order. For example, beginning with the configuration depicted in <FIG>, the access device <NUM> can be retracted to the orientation depicted in <FIG>. Thereafter, the actuation member <NUM> can be retracted to the orientation depicted in <FIG>. In certain embodiments, due to resilience of the arms 108a, 108b, this retraction of the actuation member <NUM> will also case the arms 108a, 108b to naturally or automatically return from the deformed condition in <FIG> to the configuration depicted in <FIG>. Thereafter, the tissue engagement device <NUM> can be withdrawn through the lumen of the tunneling cannula <NUM>, as depicted in <FIG>.

<FIG> depict an illustrative embodiment of the actuation mechanism <NUM> for the tissue engagement device <NUM>. As previously mentioned, other suitable mechanisms are also contemplated and are within the scope of the present disclosure. The illustrated actuation mechanism <NUM> is capable of preventing two potentially undesirable configurations of the tissue engagement device <NUM>. In particular, the actuation mechanism <NUM> is configured to prevent the access device <NUM> from being deployed prior to deployment of the arms 108a, 108b via the actuation member <NUM>, which can avoid the potentially undesirable results for such a configuration discussed above. The illustrated actuation mechanism <NUM> is further configured to prevent retraction of the actuation member <NUM> and the resultant retraction of the arms 108a, 108b, which can avoid the potentially undesirable results for such a configuration discussed above. The illustrated actuation mechanism <NUM> may be referred to as a dual interlock system. Stated otherwise, the actuation mechanism <NUM> can serve as a lock to prevent a first potentially undesirable configuration of the tissue engagement device <NUM>, and can further serve as a lock to prevent a second potentially undesirable configuration of the tissue engagement device <NUM>. In other embodiments, an interlock device may prevent only one of the potentially undesirable configurations. In still other embodiments, the actuation mechanism <NUM> may not function as an interlock device for either potentially undesirable configuration.

<FIG> depicts an exploded perspective view of an embodiment of the housing <NUM>, which includes the upper shell <NUM> and the lower shell <NUM>. The lower shell <NUM> can include the connector <NUM> at a distal end thereof, as previously described. The connector <NUM> can define a lumen 133a through which the actuation member <NUM> and the access device <NUM> can pass for advancement to a deployed state or retraction to a retracted state.

With reference to <FIG> and <FIG>, the lower shell <NUM> can define a cavity 150a into which certain components of the actuation mechanism <NUM>, or portions thereof, can be received. The upper shell <NUM> likewise defines a cavity 150b into which certain components or portions thereof can be received. When the upper and lower shells <NUM>, <NUM> are coupled to each other, the cavities 150a, 150b define a unitary volume of space.

The dual interlock property of the illustrated embodiment of the actuation mechanism <NUM> generally operates on two levels or planes. The upper level is generally defined by a lower portion of the upper shell <NUM>. The lower level is defined by the lower shell <NUM>. For example, the lower shell <NUM> includes an actuator stop <NUM>, which is a rounded protrusion that extends upwardly from a substantially flat base wall of the lower shell <NUM>. As further discussed below, the actuator stop <NUM> is configured to interact with a component in the lower level.

The lower shell <NUM> further includes a coupling protrusion <NUM> that is configured to connect with the gate <NUM>, as further discussed below. A proximal end of the lower shell <NUM> can include a key slot region 155a defined by a keying surface 153a. A proximal end of the upper shell <NUM> likewise can include a key slot region 155b defined by a keying surface 155b. When the upper and lower shells <NUM>, <NUM> are coupled to each other, the key slot regions 155a, 155b define a unitary key slot, and the keying surfaces 153a, 153b cooperate to maintain a fixed rotational orientation of the hub <NUM> as portions thereof are advanced distally into or retracted proximally from the housing <NUM>.

The upper shell <NUM> defines a recess <NUM> within which the actuation interface <NUM> can translate forward or backward. The upper shell <NUM> further defines a longitudinal channel <NUM> along which the actuation interface <NUM> can be translated forward or backward. The upper shell <NUM> also includes a transverse channel <NUM> through which a portion of the actuation interface <NUM> can be advanced.

With reference to <FIG>, the upper shell <NUM> defines a pair of stops 159a, 159b that can selectively prevent proximal movement of the shuttle <NUM>, as further described below. The stops 159a, 159b reside within the upper level along which the dual interlock mechanism operates.

With reference to <FIG>, the illustrated actuation interface <NUM> is formed as a button <NUM>, which may also be referred to as a slider. The illustrated button <NUM> is particularly well suited for actuation via a thumb of a user while the housing <NUM> is held by fingers of the hand, although other actuation grips are possible. The button <NUM> includes a proximal surface <NUM> that is contoured to receive a thumb tip of a user. The proximal surface <NUM> rises in a distal direction toward a grip <NUM>, which can provide traction for the user. While any suitable grip arrangement is contemplated, the illustrated grip includes transversely directed grooves. A distal surface <NUM> drops steeply from the apex. The user can readily grip the apex and/or upper portions of the distal surface <NUM> to apply rearward directed force for retraction of the actuation assembly <NUM>.

With reference to <FIG>, the button <NUM> can include a longitudinal guide <NUM> that is sized to slide within the longitudinal channel <NUM> of the upper shell <NUM>. The button <NUM> can further include a lateral retainer or transverse bar <NUM> that cooperates with a bottom surface of the button <NUM> to define a channel <NUM> on either side of the guide <NUM>. The channels <NUM> can receive a portion of the upper shell <NUM> that borders the longitudinal channel <NUM>.

<FIG> depict the gate <NUM> in two different operational states. In <FIG>, the gate <NUM> is closed, whereas the gate <NUM> is open in <FIG>. The gate <NUM> is positioned within the lower shell <NUM>. Accordingly, the gate <NUM> operates in the lower level of the dual interlock mechanism.

The gate <NUM> includes a base <NUM> from which two resilient arms 171a, 171b extend in the proximal direction. The base <NUM> defines an opening <NUM> sized to receive the coupling protrusion <NUM> of the lower shell <NUM> to connect the gate <NUM> to the lower shell <NUM>. The distal ends of the arms 171a, 171b cooperate with an inner surface of the base <NUM> to define a receptacle <NUM>. When the gate <NUM> is coupled to the lower shell <NUM>, the actuator stop <NUM> resides within the receptacle <NUM>.

Generally central portions of the arms 171a, 171b include inwardly projecting camming surfaces 174a, 174b, respectively. The camming surfaces 174a, 174b are configured to interact with a portion of the shuttle <NUM> to selectively open the gate <NUM>, as further described below.

The proximal ends of the arms 171a, 171b include stops 175a, 175b that are configured to abut a portion of the hub <NUM> to prevent distal movement of the hub <NUM> when the gate <NUM> is in the closed state of <FIG>. When the gate <NUM> is in the open state of <FIG>, the stops 175a, 175b are separated from each other to define a passageway <NUM> through which the portion of the hub <NUM> can pass in the distal direction.

<FIG> depicts a portion of the actuator <NUM>, which includes the actuation member <NUM> and the shuttle <NUM>. As previously mentioned, the actuator <NUM> further includes the actuation interface <NUM>.

As previously mentioned, in the illustrated embodiment, the actuation member <NUM> is a cannula that defines a lumen <NUM>. The lumen <NUM> is sized to permit passage of the access device <NUM>. A proximal end of the actuation member <NUM> can be coupled to a body <NUM> of the shuttle <NUM> in any suitable manner.

The shuttle <NUM> includes a pair of upwardly projecting sidewalls <NUM> that cooperate to define a longitudinal channel <NUM> and a lateral channel <NUM>. The channels <NUM>, <NUM> are sized to receive the longitudinal guide <NUM> and the transverse bar <NUM> that project downwardly from the button <NUM>.

With reference to <FIG> and <FIG>, in coupling the button <NUM> with the shuttle <NUM> and the upper shell <NUM> of the housing <NUM>, the longitudinal guide <NUM> and the transverse bar <NUM> are inserted through the longitudinal channel <NUM> and the transverse channel <NUM> of the upper shell <NUM> and into the longitudinal channel <NUM> and the lateral channel <NUM> of the shuttle <NUM>. The button <NUM> and the shuttle <NUM> can be connected together in any suitable manner, including one or more of friction fit, snap fit, adhesive, etc. Once the button <NUM> and the shuttle <NUM> are connected, the button <NUM> is free to slide forward and rearward within the longitudinal channel <NUM> of the upper shell.

With reference again to <FIG>, the shuttle <NUM> further includes a downward protrusion, such as a wedge <NUM>. The wedge <NUM> is configured to operate on the lower plane of the interlock mechanism. In particular, the wedge <NUM> can be positioned between the proximal portions of the arms 171a, 171b of the gate <NUM>. The wedge <NUM> can include camming surfaces that interact with the camming surfaces 174a, 174b of the gate <NUM> to urge apart the resiliently flexible arms 171a, 171b. The wedge <NUM> can interact with the actuator stop <NUM> (<FIG>) to prevent the shuttle from traveling too far in a distal direction. In particular, the stop <NUM> may be positioned so as to ensure that a distal end of the actuation member <NUM> stops at a desired position relative to the actuated arms 108a, 108b (see <FIG>), such as, for example, a position that is slightly proximal of the tissue engaging members 109a, 109b of the actuated arms 108a, 108b. Such as position may, for example, avoid pushing an engaged portion of the target tissue layer off of the actuated engaging members 109a, 109b.

With continued reference to <FIG>, the illustrated embodiment of the shuttle <NUM> includes a pair of laterally and proximally projecting resiliently flexible arms 185a, 185b. The arms 185a, 185b include stops 186a, 186b at the proximal ends thereof. The arms 185a, 185b and stops 186a, 186b are positioned to operate on the upper level of the interlock mechanism. In particular, the arms 185a, 185b may be flexed inwardly as the actuator <NUM> is advanced distally to deploy the arms 108a, 108b via the actuation member <NUM> via contact with a portion of the hub <NUM>, as discussed further below. Upon distal advancement of the hub <NUM> to deploy the access device <NUM>, however, the arms 108a, 108b can automatically return to a natural extended state, at which point the stops 186a, 186b engage the stops 159a, 159b of the upper shell <NUM>. The shuttle <NUM> can be retained in this position until the hub <NUM> is returned to a proximal position to free the stops 186a, 186b from the stops 159a, 159b, as discussed further below with respect to <FIG>.

<FIG> depicts the access assembly <NUM>, which includes the access device <NUM> or piercing member and the hub <NUM>. A proximal end of the access device <NUM> can be coupled to a body <NUM> of the hub <NUM> in any suitable manner. The access device <NUM> can define a lumen <NUM> through which communication with a region beneath the target tissue layer (e.g., the pericardial space) can be established once the access device <NUM> pierces through the target tissue layer. For example, a guide wire may be delivered through the lumen <NUM>.

The hub <NUM> includes a neck <NUM> that is shaped to fit within the key slot defined by the keying surfaces 153a, 153b of the lower and upper shells <NUM>, <NUM>. The neck <NUM> can include outwardly projecting flanges that, in cooperation with the keying surfaces 153a, 153b, prevent rotational movement of the hub <NUM> about a longitudinal axis thereof.

The hub <NUM> can include a grip <NUM>, which may be positioned proximal of the neck <NUM>. The grip <NUM> can be sized and configured to be readily manipulated by a user, such as by using a second hand while the user holds the housing <NUM> with a first hand. In the illustrated embodiment, a medical connector <NUM> is positioned at a proximal end of the hub <NUM>. Any suitable connection interface is contemplated for the medical connector <NUM>, which can serve to couple the hub <NUM> with any suitable medical device(s) or equipment for delivering and/or withdrawing fluid to/from a region accessed by the distal end of the access device <NUM>. In the illustrated embodiment, the connector <NUM> comprises a Luer fitting <NUM>.

With continued reference to <FIG>, the hub <NUM> includes three distally projecting tines, prongs, or arms <NUM>, 194a, 194b. In the illustrated embodiment, the arms <NUM>, 194a, 194b substantially form a trident shape. The central arm <NUM> is shorter than the outer arms 194a, 194b and includes a stop <NUM> at a distal end thereof. The stop <NUM> operates at the lower level of the interlock system, and is configured to interact with the stops 175a, 175b of the gate <NUM>.

An upward protrusion 196a, 196b is positioned at the distal end of each of the side arms 194a, 194b. The protrusions 196a, 196b are positioned to operate at the upper level of the interlock system. In particular, the protrusions 196a, 196b are configured to bend the proximal ends of the arms 185a, 186a inward when the hub <NUM> is drawn proximally to a retracted state, thereby permitting proximal movement of the shuttle to a retracted state, as shown in and discussed further with respect to <FIG>.

Some of the features of the illustrated actuation mechanism <NUM> include a pair of elements to accomplish a given function. For example, the two arms 185a, 186a interact with the two stops 159a, 159b to prevent retraction of the actuation member <NUM> under certain conditions. In other embodiments, only a single set of interacting features may be used. In some instances, however, a redundant set of interacting features can provide strength, stability, and/r balance to the system and/or act a as a backup or failsafe.

<FIG> demonstrate various stage of operation of the actuation mechanism <NUM>. Many details regarding these stages of operation have already been provided. <FIG> and the discussion that follows are to provide further clarity regarding to the manners in which the various components interact (e.g., to achieve a dual interlock mechanism). Certain features that were discussed with respect to at least <FIG> may not be repeated in the following discussion, as the purpose of the present discussion is to provide a streamlined understanding of the illustrated actuation mechanism <NUM>. The further details disclosed with respect to at least <FIG> are fully applicable here, but will be omitted for the sake of brevity and clarity.

<FIG> is a cross-sectional view of the tissue engagement device <NUM> along the view line 7A-7A in <FIG>, as coupled with the tunneler cannula <NUM>, which is also shown in cross-section. This drawing depicts the shuttle <NUM> in a fully retracted configuration. Correspondingly, the drawing depicts the actuation member <NUM> in the retracted configuration. Likewise, the access device <NUM> and the hub <NUM> are in the retracted configuration. Accordingly, the tissue engagement device <NUM> is in the fully retracted configuration. <FIG> corresponds with the view of the distal end of the tissue engagement device <NUM> depicted in <FIG>. In this operational state, the gate <NUM> is closed and interacts with the central prong <NUM> of the hub <NUM> to prevent deployment of the access device <NUM>.

In <FIG>, the tissue engagement device <NUM> is in a partially deployed state. In particular, the shuttle <NUM> has been advanced distally, but not yet to its distal-most orientation. That is, the shuttle <NUM> has been advanced to an intermediate phase of deployment. The gate <NUM> has begun to open, but is not yet open sufficiently wide to permit the distal passage of the central prong <NUM> of the hub <NUM>.

<FIG> depicts the actuation mechanism <NUM> of the tissue engagement device <NUM> in another partially deployed state. In this state, the shuttle <NUM> has been advanced to its distal-most position, and is thus fully deployed. However, the hub <NUM> and the access device <NUM> remain in their retracted state. The full distal movement of the shuttle <NUM> has opened the gate <NUM> to create the passageway <NUM>, which is now sufficiently large to permit passage of the central prong <NUM> of the hube <NUM> in a distal direction. <FIG> corresponds with the view of the distal end of the tissue engagement device <NUM> depicted in <FIG>.

<FIG> depicts the actuation mechanism <NUM> of the tissue engagement device <NUM> in a fully deployed state. Specifically, the shuttle <NUM> and the actuation member <NUM> are in their distal-most orientations, and the hub <NUM> has been moved distally to at least partially deploy the access device <NUM>.

In this operational mode, the hub <NUM> is able to move distally and proximally in an unconstrained manner, or at least unconstrained within a range permitted by the confines of the housing <NUM>. Unconstrained distal movement permits a user to select the amount of force to be applied to the access device <NUM> to pierce the target tissue layer, as well as the distance (within a limited range) to which the access device <NUM> will be inserted through the tissue layer.

Unconstrained proximal movement can be an advantageous safety feature, in some instances. For example, if a user inserts the access device <NUM> through the tissue layer, but then becomes distracted or otherwise inadvertently releases the hub <NUM>, the underlying layer can be protected from damage, such as by pushing the access device <NUM> in the proximal direction. In the context of pericardial access, for example, a distal tip of the access device <NUM> may be readily pushed rearward by the beating heart if the practitioner maintains a grip on the housing <NUM>, but releases a grip on the hub <NUM>.

Movement of the hub <NUM> and its upward protrusions 196a, 196b in the distal direction releases the arms 185a, 185b of the shuttle <NUM> to automatically resiliently expand outwardly into contact with the sides of the housing <NUM>. The proximal ends of the arms 185a, 185b come into contact with the distal faces of the stops 159a, 159b, which prevents the shuttle <NUM> from moving distally in the present configuration.

<FIG> depicts the actuation mechanism <NUM> in a partially deployed state again, with the hub <NUM> having been withdrawn distally to a configuration that permits retraction of the actuation member <NUM>. Moreover, movement of the hub <NUM> and its upward protrusions 196a, 196b in the proximal direction compresses the arms 185a, 185b of the shuttle <NUM> to be displaced inward and out of contact from the distal faces of the stops 159a, 159b. This configuration permits proximal movement of the shuttle <NUM> to draw the actuation member <NUM> into the retracted position.

<FIG> depict various stages of illustrative methods for engaging a target tissue layer and accessing a space beneath the same. Many details regarding these method stages have already been provided. <FIG> and the discussion that follows are to provide further clarity regarding to the methods. Certain features that were discussed with respect to at least <FIG> may not be repeated in the following discussion, as the purpose of the present discussion is to provide a streamlined understanding of the illustrated method stages. The further details disclosed with respect to at least <FIG> are fully applicable here, but will be omitted for the sake of brevity and clarity.

One illustrative method includes each stage depicted in <FIG> in the sequential order shown. In the illustrative method, the pericardial space of the heart of a patient is accessed. Other methods are contemplated, including some that do not employ each method stage illustrated and/or that use additional stages. Moreover, other suitable contexts (e.g., target tissue layers other than the pericardium) are contemplated.

<FIG> depicts an early stage of an illustrative method for accessing a region beneath a tissue layer. In particular, the method is used to access the pericardial space <NUM> between the pericardium <NUM> and the epicardium <NUM> of the heart <NUM> of a patient P.

In the illustrated method, the tunneling assembly <NUM> is provided, such as by being removed from sterile packaging. In some embodiments, the obturator <NUM> and the tunneling cannula <NUM> are provided in a preassembled state. In other instances, an earlier stage of the method include coupling the obturator <NUM> to the tunneling cannula <NUM> into the configuration show.

In some embodiments, an anterior approach may be used in directing the tunneling assembly <NUM> toward the heart <NUM>. In other embodiments, an inferior or posterior approach is used, which can require passing the tunneling assembly <NUM> through the diaphragm. Such an approach may also referred to as a transdiaphragmatic or subdiaphragmatic approach. Each such approach may be referred to as a subxiphoid approach. The different approaches may result in different angles relative to the heart. In still further instances, an intercostal approach, e.g., between the 6th and 7th ribs may be used and may provide direct access to different areas of the heart. In some instances, the intercostal space allows the apex of the heart to be accessed, and so such an approach is also called a transapical approach.

In view of the foregoing, a number of different approaches to the heart are contemplated. The tissue engagement systems <NUM>, <NUM> and tissue engagement devices <NUM> disclosed herein can be particularly well suited for any such approach to the heart. In particular, the systems <NUM>, <NUM> and devices <NUM> can be particularly well suited to engage, grasp, pull, and or otherwise manipulate the pericardium <NUM> at any number of different approach angles. For example, the tissue engagement devices <NUM> can work effectively at shallow angles of approach or steep angles of approach. Indeed, certain embodiments are capable of functioning well at approach angles of from <NUM> degrees (e.g., a fully transverse orientation) through <NUM> degrees (e.g., a fully orthogonal orientation). With respect to a <NUM>-degree approach, a distal end of the device <NUM> can come into contact with the pericardium and create a ripple, or a substantially vertical (or upwardly extending) wall of tissue ahead of the distal end of the device. This phenomenon is similar to pushing a piece of fabric along a tabletop using a finger to generate a ripple or wave response. A local wave or ripple can create an at least somewhat transverse surface, relative to a distal end of the device <NUM>, to which the tines can engage (e.g., grasp, grab, embed within, snag, catch, etc.).

<FIG> depicts a stage at which the tunneling assembly <NUM> has been advanced through an incision <NUM> in the skin <NUM> of the patient. The blunt tip <NUM> of the obturator <NUM> has been urged through the connective tissue <NUM> of the patient P into contact with an external surface of the pericardium <NUM>.

<FIG> depicts a stage at which the obturator <NUM> is decoupled from the tunneling cannula <NUM> and removed therefrom. The tube <NUM> portion of the tunneling cannula <NUM> is left in the tissue <NUM> to provide a channel to the pericardium <NUM>.

<FIG> depicts a stage in which the tissue engagement device <NUM> is coupled with the tunneler cannula <NUM>. In particular, the sheath <NUM> is advanced through the tube <NUM> and toward the pericardium <NUM>.

<FIG> depicts another stage in which the tissue engagement device <NUM> is in the fully retracted configuration, such as that of <FIG> and <FIG>, with the tissue engagement members 109a, 109b (e.g., the distal tips) of engagement arms 108a, 108b positioned at the target tissue layer, which in this instance is the pericardium <NUM>. The tissue engagement device <NUM> is fully coupled with the tunneler cannula <NUM>.

<FIG> depicts another stage in which the tissue engagement device <NUM> is in the partially deployed state, such as that of <FIG>, with the actuation member <NUM> advanced distally to an intermediate position to embed the tissue engagement members 109a, 109b arms in the pericardium <NUM>. In the illustrated embodiment, the tissue engagement members 109a, 109b do not extend through a full thickness of the pericardium <NUM> to pass into the pericardial space <NUM>. Stated otherwise, the engagement members 109a, 109b do not pass through an interior or bottom surface of the pericardium <NUM>. This can result from the initial shallow angle of the engagement members 109a, 109b relative to the pericardium <NUM>, and further, from a shallow deployment path for each of the engagement members 109a, 109b. By "shallow deployment path," it is meant that the path traced by the engagement members 109a, 109b (e.g., a distal tip thereof) extends only a small longitudinal distance from the distal end of the actuation member <NUM>, or from the starting point of the respective engagement member 109a, 109b. In various embodiments, each engagement member 109a, 109b progresses distally from its staring point to a maximum longitudinal distance (i.e., a distance as measured only in the longitudinal direction, or in a direction that is collinear with or parallel to a longitudinal axis of the actuation member <NUM>) that is no greater than <NUM>, <NUM>, <NUM>, or <NUM> millimeters. Indeed, in some embodiments, an entirety of the path traced by each engagement member 109a, 109b may have no longitudinal component (e.g., may be entirely lateral), or may have a longitudinal component that progresses only in the proximal direction, or stated otherwise, only moves laterally and proximally from the starting point.

In various embodiments, each engagement member 109a, 109b defines a maximum length. For example, in the illustrated embodiment, the maximum length of each engagement member 109a, 109b is the distance from the distal point thereof to a primary bend (e.g., the only bend in each arm 108a, 108b that is readily apparent in <FIG>). In various embodiments, each engagement member 109a, 109b progresses distally from its starting point to a maximum longitudinal distance that is no greater than <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> times the maximum length of the engagement member 109a, 109b.

It may alternatively be stated that each engagement member 109a, 109b follows a deployment path that is substantially transverse to the surface of the target tissue layer. The substantially transverse deployment of the engagement members 109a, 109b can embed the engagement members 109a, 109b within the tissue layer and can put the tissue layer under tension in the transverse direction. A substantially transverse deployment path also reduces the risk of contacting and/or damaging an underlying tissue layer, such as the epicardium <NUM>.

In other embodiments, at least a portion of one or more of the engagement members 109a, 109b may extend through a full thickness of the target tissue layer. Stated otherwise, in other embodiments, the engagement members 109a, 109b may pierce through the bottom or inner surface of the tissue layer.

<FIG> depicts a stage in which the tissue engagement device <NUM> is in the further partially deployed state, such as that of <FIG> and <FIG>, with the actuation member <NUM> advanced to the distal-most position to further embed the engagement members 109a, 109b in the pericardium <NUM>. In the illustrated embodiment, the engagement members 109a, 109b extend laterally outward at an angle of approximately <NUM> degrees relative to the adjacent, proximal portions of the arms 108a, 108b. Other angles relative to the arms 108a, 108b in this fully deployed state are also contemplated, as further discussed below.

<FIG> depicts a stage in which the tissue engagement device <NUM> is in the same configuration as that depicted in <FIG> and in which the tissue engagement device <NUM> is drawn proximally to enlarge the pericardial space <NUM> between the pericardium <NUM> and the epicardium <NUM> in the vicinity of the engagement members 109a, 109b. Such a separation event may result in tenting of the pericardium <NUM> at the engagement position. This tenting is shown only schematically in <FIG>, as the tenting can be quite steep in some instances, such as may result from vacuum or other forces within the pericardial space <NUM> as the pericardium <NUM> is drawn upward in the manner shown.

<FIG> depicts a stage in which the tissue engagement device <NUM> has been moved to the fully deployed state, such as that of <FIG> and <FIG>, in that both the actuation member <NUM> and the access device <NUM> have been advanced distally. At the illustrated stage, the access device <NUM> has pierced the pericardium <NUM> to provide access to the pericardial space <NUM>. Communication with pericardial space <NUM>, such as for the introduction or removal of fluid, can be achieved via the medical connector <NUM>.

As discussed with respect to <FIG>, tenting in the vicinity of the actuation arms 108a, 108b may be quite steep. However, the region between the arms 108a, 108b may be substantially planar due to tension provided by the arms 108a, 108b. The access device <NUM> thus may be readily advanced through the portion of the pericardium <NUM> that is held in tension, which is relatively unaffected by the neighboring tenting.

In particular, a distal end of the access device <NUM> may be pointed, or angled relative to a longitudinal axis of the device. As a result, insertion of the device <NUM> is much easier through a planar region that is substantially orthogonal to the longitudinal axis of the device-e.g., through the region between the arms 108a, 108b-than it is through regions that have shallower angles relative to the tip, such as the steep tented surfaces that surround the region that is held between the arms 108a, 108b. For this reason, it can be advantageous in some embodiments to ensure that a tip of the access device <NUM> passes through a line that extends between the arms 108a, 108b when the arms 108a, 108b are in the deployed state.

<FIG> depicts a stage in which the tissue engagement device <NUM> remains in the fully deployed state and a distal end of a guidewire <NUM> has been advanced distally through the access device <NUM> into the pericardial space <NUM>. The guidewire 200may be of any suitable variety or size. In various embodiments, a thickness of the guidewire can be <NUM> inches (<NUM> millimeters) or <NUM> inches (<NUM> millimeters).

<FIG> depicts another stage in which the tissue engagement device <NUM> has been returned to the partially deployed state, such as that of <FIG> and <FIG>. In particular, the access device <NUM> has been retracted. From this stage, the actuation member <NUM> may subsequently be retracted and then the device <NUM> can be removed from the patient P. The distal end of the guidewire <NUM> can remain in place within the pericardial space <NUM> as the tissue engagement device <NUM> is withdrawn. Although the arms will be in a retracted state during removal of the device <NUM>, positioning of the guidewire <NUM> will be relatively unaffected during withdrawal of the device <NUM>. In particular, as the device <NUM> is withdrawn, the arms 108a, 108b pass by the guidewire <NUM>. State dotherwise, the guidewire <NUM> can pass through openings <NUM>, <NUM> defined by the arms 108a, 108b, even though the arms 108a, 108b cover the distal opening of the actuation member <NUM>. The openings <NUM>, <NUM> can be seen, for example, in <FIG> and <FIG>.

<FIG> depicts an embodiment of an engagement element <NUM> during a stage of a manufacturing process therefor. In the illustrated embodiment, the engagement element <NUM> is formed from a unitary piece of material. Any suitable material is contemplated. The material can desirably exhibit the properties described herein. In some embodiments, the engagement element <NUM> is formed from a unitary piece of stainless steel that has been formed as a tube.

Prior to the stage of the manufacturing method depicted in <FIG>, portions of the tube are cut or otherwise removed to form the arms or tines 108a, 108b (the tine 108b is hidden in <FIG>, but is shown in other figures, such as <FIG>). In some embodiments, the tines are laser cut. The tines 108a, 108b can extend distally from the remaining portion of the original tube, which is also referred to herein as the cannular base <NUM>.

The tines 108a, 108b can each include a relatively wide base region <NUM>, which can extend distally from a distal end of the cannular base <NUM>. In various embodiments, a width of the base region <NUM> can be no greater than about <NUM>/<NUM>, <NUM>/<NUM>, or <NUM>/<NUM> of a diameter of the cannular base <NUM>. The base region <NUM> can have an angled step down to a displacement region <NUM>. The displacement region <NUM> of each arm is the region of greatest displacement during use. A thinner displacement region <NUM> can permit a compact or low profile design. In particular, a thin displacement region can be desirable where the tines 108a, 108b cross one another in the retracted orientation and move past each other during deployment. In various embodiments, a thickness of the displacement region is no greater than about <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, or <NUM>/<NUM> of the diameter of the cannular base <NUM>.

Removal of portions of the original tube can also yield a piercing surface 214a, 214b (see also, e.g., <FIG>). In the illustrated embodiment, the piercing surfaces 214a, 214b are fashioned as pointed ends or barbs at the distal tips of each tine 108a, 108b. An attack angle α of the piercing surfaces 214a, 214b can be selected to provide ready engagement with the target tissue layer. In various embodiments, the attack angle α is no greater than about <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> degrees.

<FIG> is a side elevation view of the engagement element <NUM> after further processing, and <FIG> is a top plan view thereof. In further process stages that result in the configuration depicted in <FIG> and <FIG>, the tines 108a, 108b are bent about multiple axes. In some embodiments, a primary bend 216a, 216b is made by rotating the distal end of the tines 108a, 108b about the y-axis. In particular, the tine 108a is rotated in a first direction about the y-axis, and the tine 108b is rotated in an opposite direction about the y-axis. In various embodiments, an angle of plastic deformation that results from the bending can be within a range of from about <NUM> degrees to about <NUM> degrees, from about <NUM> degrees to about <NUM> degrees, or may be no more than about <NUM>, <NUM>, <NUM>, or <NUM> degrees.

The primary bends 216a, 216b can yield the engaging members 109a, 109b. Retention surfaces 219a, 219b at the proximal sides of the engaging members 109a, 109b may vary in effectiveness at holding the target tissue layer, depending on the angle of plastic deformation of the bends 216a, 216b.

The tines 108a, 108b can be rotated and permanently bent in the same direction about the z-axis. Additionally, or alternatively, the tines 108a, 108b can be rotated and permanently bent in opposite directions about the x-axis. The latter bending may be referred to as splining, and can permit the tines 108a, 108b to move past one another when an additional permanent bend, or secondary bend 218a, 218b (<FIG>) is formed.

As shown in <FIG>, in some embodiments, the tines 108a, 108b define a natural orientation in which the lateral width at a distal end of the tines 108a, 108b is greater than a diameter of the cannular base <NUM>. As a result, when the tines 216a, 216b are received within the sheath <NUM>, which has an interior diameter that only slightly exceeds the outer diameter of the base <NUM>, the tines 108a, 108b are spring-loaded. That is, the tines 108a, 108b naturally attempt to assume the configuration shown in <FIG> and <FIG>, but are prevented from doing so by the sheath <NUM> (see <FIG>). Providing such a pre-load to the tines 108a, 108b allows them to naturally return to the constrained orientation depicted in <FIG> after the actuation member <NUM> is retracted.

<FIG> depict various views of the engagement element <NUM> when in the constrained configuration that is provided by the sheath <NUM>, such as in the arrangement depicted in <FIG>. For clarity, the sheath <NUM> is not shown in these views. In this operative state, the tines 108a, 108b cross each other at a position distal of the distal end of the cannular base <NUM>. In this particular embodiment, the tines 108a, 108b contact one another at a crossing point <NUM>. Other embodiments may cross one another near a crossing point, but not contact each other thereat. The crossing point in such arrangements may be the midpoint of a minimum distance between the tines 108a, 108b where they cross. As previously mentioned, the tines 108a, 108b can define openings <NUM>, <NUM> through which a guidewire may readily pass during use.

As can be appreciated from the foregoing, in certain embodiments, the tines 108a, 108b can be positioned diametrically opposite one another. When in a retracted state, the tines 108a, 108b can be in a substantially bent configuration. When actuated, a proximal portion of each tine 108a, 108b that is constrained within the sheath <NUM> can be substantially straightened. The straightened tines may be substantially parallel to each other and/or substantially parallel to a longitudinal axis of the cannular base <NUM>. A length of each tine 108a, 108b may be sufficiently long to prevent plastic deformation of the tines 108a, 108b during deployment. The tines are formed in an elastically resilient fashion that permits them to automatically and naturally return to the pre-deployment state after deployment.

With reference to <FIG>, certain embodiments of the engagement element <NUM> can include a centering protrusion <NUM>. In the illustrated embodiment, the centering protrusion <NUM> is an inwardly directed bump <NUM> that is impressed into the cannular base <NUM>. In other embodiments, the centering protrusion <NUM> may instead be formed from a different material and fixedly secured to the inner wall of the cannular base <NUM>.

As shown in <FIG>, the centering protrusion <NUM> constrains movement of the actuation member <NUM> (e.g., constrains lateral movements relative to a longitudinal axis), which in turn constrains movement of the access device <NUM>. This arrangement can ensure that a distal tip <NUM> of the access device <NUM> is substantially centered relative to the engagement element <NUM>. In some embodiments, during actuation of the access device <NUM>, the distal tip <NUM> can pass through a line L that extends through the distal tips of the tines 108a, 108b. Such an arrangement can aid in delivering the tip <NUM> through a portion of the pericardium that is between the tines 108a, 108b and is in tension due thereto. For example, this can permit the tip <NUM> to pass through a relatively flat or plateaued region at the apex of a tented portion of the pericardium, as previously discussed.

As shown in <FIG>, in some embodiments, the access device <NUM> can be a needle <NUM> having a centered distal tip <NUM>. In some instances, the needle <NUM> is formed with a bevel <NUM> (e.g., one or more of a bias grind, a lancet grind, etc.), and is then bent to move the distal tip <NUM> into alignment with a longitudinal axis of the needle <NUM>.

<FIG> depict another embodiment of a tissue engagement system <NUM> that can resemble the tissue engagement systems discussed above in many respects. Accordingly, like features are designated with like reference numerals, with the leading digits incremented to "<NUM>. " Relevant disclosure set forth above regarding similarly identified features thus may not be repeated hereafter. Moreover, specific features of the tissue engagement system <NUM> may not be shown or identified by a reference numeral in the drawings or specifically discussed in the written description that follows. However, such features may clearly be the same, or substantially the same, as features depicted in other embodiments and/or described with respect to such embodiments. Accordingly, the relevant descriptions of such features apply equally to the features of the tissue engagement system <NUM>. Any suitable combination of the features and variations of the same described with respect to the tissue engagement systems discussed above can be employed with the tissue engagement system <NUM>, and vice versa.

Referring to <FIG>, the system <NUM> for engaging a tissue layer and for providing access to a region beneath the tissue layer includes a tissue engagement element <NUM> having a cannular base or housing <NUM> with integrated tissue engaging members 308a, 308b, and a cannula <NUM> to activate the tissue engaging members 308a, 308b within the lumen of the housing <NUM>, and a tissue piercing member <NUM> within with lumen of the cannula <NUM>, to secure access to the region beneath the tissue layer.

Referring to <FIG> there is depicted an embodiment of a system <NUM> with the cannula <NUM> and the tissue piercing member <NUM> retracted within the housing <NUM>, such that the cannula <NUM> and the tissue piercing member <NUM> are not in contact with the tissue engaging members 308a, 308b.

Referring to <FIG> there is shown an embodiment of the housing <NUM> with the tissue engaging members 308a, 308b fully deployed. The distal end of the cannula <NUM> is advanced to the distal end of the housing <NUM>, thereby causing the tissue engaging members 308a, 308b to deploy outward.

Referring to <FIG> there is shown an embodiment of the system <NUM>, with the distal end of the cannula <NUM> advanced from the proximal end 310a of the tissue engaging member 308a to the distal end of the housing <NUM>, thereby deploying the tissue engaging member 308a. The tissue engaging member 308b is deployed in like manner. The tissue piercing member <NUM> is advanced beyond the distal end of the housing <NUM>.

Referring to <FIG> there is shown a front view of one embodiment depicting the offset nature of the tissue engaging members 308a, 308b at the distal end of the housing <NUM>.

Referring to <FIG> there is depicted a side view of the engagement of a tissue layer <NUM> by the tissue engaging members 308a, 308b, and the deployment of the tissue piercing member <NUM> into the space under the tissue layer <NUM>.

As shown in these drawings, the illustrated system <NUM> includes an elongated housing <NUM>, which may also be referred to as a cannula, having a proximal and distal end. The distal end terminates at a distal tip of the needle <NUM> when said needle <NUM> is extended as in <FIG> and the distal end terminates at the distal tip of the housing <NUM> when said needle <NUM> is retracted as in <FIG>. The needle <NUM> can be advanced to aid insertion into the patient skin as in <FIG>, and then retracted as in <FIG> as the device <NUM> is moved towards the tissue layer <NUM> to be engaged, to reduce damage to tissues that could be caused by an extended needle. The illustrated embodiment is particularly well suited for providing access to the pericardial space using a subxiphoid approach. The non-deployed tissue engaging members 308a, 308b as shown in <FIG> may effectively pass through soft tissue of a patient until contacting the pericardium, and can be sufficiently blunt to inhibit puncture or piercing of the pericardium or other tissues when advanced.

The housing <NUM> may be formed of any suitable material. In some embodiments, the housing <NUM> is metallic, whereas in other or further embodiments, the housing <NUM> can be formed of a substantially rigid plastic.

The needle <NUM> may be formed of any suitable material. For example, in some embodiments, the needle <NUM> is formed of stainless steel. The material is chosen such that it is sufficiently rigid to pierce the tissue layer.

The cannula <NUM> may be formed of any suitable material. For example, in some embodiments, the cannula <NUM> is formed of stainless steel. The material chosen such thatis sufficiently rigid and strong to deploy the tissue engaging members 308a, 308b.

During use of the system <NUM>, the needle <NUM> may be extended past the housing <NUM> to be inserted into a patient to the desired location, and the proximal end of the housing <NUM> can remain at an exterior of the patient. In one embodiment, the system is inserted into the patient with the needle <NUM> in the retracted position as shown in <FIG> via an incision in the patient at the desired location. In some embodiments, the system <NUM> includes one or more actuators at the proximal end by which a user can deploy the needle <NUM> and/or the cannula <NUM>. Any suitable actuator arrangement is possible. In other or further embodiments the cannula <NUM> and the access needle <NUM> may be manipulated directly by a user and advanced through the housing <NUM> without relying on any actuators.

In one embodiment, the system <NUM> comprises a first actuator at the proximal end of the system that is configured to deploy and/or retract the needle <NUM>. While any suitable actuator arrangement is contemplated, the illustrated actuator comprises a button, switch, tab, or protrusion that is coupled to a proximal portion of the needle <NUM>. In the illustrated embodiment, a relatively large annular space is depicted between an exterior surface of the access needle <NUM> and an interior surface of the cannula <NUM> and the interior surface of the housing <NUM>. In some embodiments, this annular space is proportionally much smaller, minimized, or substantially eliminated. For example, a snug fit, a loose fit, or a minimal gap may be provided between at least a portion of an interior surface of the sidewall of the housing <NUM> and at least a portion of an exterior surface of the cannula <NUM>, and the access needle <NUM>, which can desirably reduce an overall diameter (e.g., maximum cross-sectional width, where the cross-section is not necessarily circular) of the system <NUM>, or more particularly, an outer diameter of the housing <NUM>. Such an arrangement also can reduce or avoid coring of tissue by the housing <NUM> as the system <NUM> is advanced into a patient.

<FIG> depicts the distal end of the system <NUM> as having been advanced into the patient and as having engaged the tissue layer <NUM>. The tissue layer <NUM> is pulled back and the needle <NUM> is advanced into the space created under the tissue layer <NUM>. A guidewire may be advanced through the lumen of the tissue piercing layer into the space under the tissue layer.

With reference again to <FIG>, it is preferable that the length of the tissue engagement member 308a, 308b as it extends along the housing <NUM> is sufficiently long to prevent plastic deformation of the tissue engagement member 308a, 308b during actuation by the cannula <NUM>.

With reference again to <FIG>, the shape of the distal end of the tissue engagement members 308a, 308b are sharp such that they can cut into the tissue layer <NUM>. The prongs are sufficiently long to engage the tissue layer <NUM>, but they are not longer than the diameter of the housing <NUM>, such that they do not extend beyond the border of the housing <NUM> when non-actuated as shown in <FIG>. The prongs that engage the tissue layer may be bent at <NUM> degrees as shown, or they may be bent between <NUM> degrees to <NUM> degrees to enable tissue engagement and retention. The sharp tip of the prong may be cut from the center as shown, or it may be cut a variety of angles, or it may not be cut at any angle, to enable tissue engagement and retention. The prong profile and sharpness are designed to engage the tissue layer <NUM> at a low angle or a high angle. This allows for low and high approach angles, but particularly low-angles that can be particularly suitable for a low-angle, subxiphoid approach to the heart, for example.

With reference again to <FIG> and <FIG>, the tissue engaging members 308a, 308b may be offset as shown, or they may not be offset such that they do not pass each other during activation by the cannula <NUM>. The length of the prongs at the distal end of the tissue engaging members 308a, 308b constructed such that they do not extend beyond the diameter of the housing <NUM> when not activated by the cannula.

Any methods disclosed herein comprise one or more steps or actions for performing the described method. The method steps and/or actions may be interchanged with one another. In other words, unless a specific order of steps or actions is required for proper operation of the embodiment, the order and/or use of specific steps and/or actions may be modified.

References to approximations are made throughout this specification, such as by use of the terms "about" or "approximately. " For each such reference, it is to be understood that, in some embodiments, the value, feature, or characteristic may be specified without approximation. For example, where qualifiers such as "about," "substantially," and "generally" are used, these terms include within their scope the qualified words in the absence of their qualifiers. For example, where the term "substantially planar" is recited with respect to a feature, it is understood that in further embodiments, the feature can have a precisely planar orientation.

Any reference throughout this specification to "certain embodiments" or the like means that a particular feature, structure or characteristic described in connection with that embodiment is included in at least one embodiment. Thus, the quoted phrases, or variations thereof, as recited throughout this specification are not necessarily all referring to the same embodiment or embodiments.

Claim 1:
A tissue engagement device (<NUM>, <NUM>) comprising:
a sheath (<NUM>);
a cannular base (<NUM>, <NUM>);
a first arm (108a, 308a) that extends from the cannular base (<NUM>, <NUM>), at least a proximal portion of the first arm (108a, 108b) being within the sheath (<NUM>), the distal end of the first arm (108a, 308a) comprising a first tissue engaging member (109a) with a distal tip, said distal tip having a first piercing surface (214a);
a second arm (108b, 308b) that extends from the cannular base (<NUM>, <NUM>), at least a proximal portion of the second arm (108b, 308b) being within the sheath (<NUM>), the distal end of the second arm comprising a second tissue engaging member (109a) with a distal tip, said distal tip having a second piercing surface (214b); and
an actuation cannula (<NUM>, <NUM>) within the sheath (<NUM>), the actuation cannula (<NUM>, <NUM>) being configured to move within the sheath (<NUM>) between a retracted position and an extended position,
wherein the first arm (108a, 308a) and the second arm (108b, 308b) cover a distal end of the actuation cannula (<NUM>, <NUM>) when the actuation cannula (<NUM>, <NUM>) is in the retracted position,
characterized in that distal movement of the actuation cannula (<NUM>, <NUM>) to the extended position moves at least a portion of each of the first and second arms (108a, 308a, 108b, 308b) into a region between an exterior surface of the actuation cannula (<NUM>, <NUM>) and an interior surface of the sheath (<NUM>) and uncovers the distal end of the actuation cannula (<NUM>, <NUM>),
wherein the first and second engaging members extend laterally outward at an angle relative to the respective first and second arms (108a, 308a, 108b, 308b) such that each of the first piercing surface (214a) and the second piercing surface (214b) is configured to embed within a layer of tissue and move in a direction transverse to the surface of the target tissue layer as the actuation cannula (<NUM>, <NUM>) moves distally to the extended position to put a region of the layer of tissue under tension between the first arm (108a, 308a) and the second arm (108b, 308b).