Patent Description:
<CIT> discloses methods and devices for pericardial access. <FIG> depicts access device (<NUM>) which comprises a tissue-piercing member (<NUM>), a first guide element (<NUM>), a second guide element (<NUM>), a sheath (<NUM>), a tissue-piercing member actuator (<NUM>), a sheath actuator (<NUM>), and a tissue-engaging member (not shown). <FIG> depicts one variation of a tissue-piercing member (<NUM>) that may be used with the access device (<NUM>) described immediately above. As shown there, the tissue-piercing member (<NUM>) comprises a body (<NUM>) having a tissue-piercing distal tip (<NUM>), a plurality of side apertures (<NUM>), and one or more working longitudinal lumens (not shown) extending at least partially therethrough.

In order that the invention may be readily understood, embodiments of the invention are illustrated by way of examples in the accompanying drawings, in which:.

The present invention is defined by the appended claims only, in particular by the scope of appended independent claim <NUM>. Reference(s) to "embodiments" throughout the description which are not under the scope of the appended claims merely represents possible exemplary executions and are therefore not part of the present invention.

Minimally invasive access to the pericardial space is required for diagnosis and treatment of a variety of arrhythmias and other conditions. Access to the space may be initiated using a large diameter (for example, about 17Ga) Tuohy-style needle via the subxiphoid approach. A guidewire (for example, about <NUM> inches (about <NUM>) in outer diameter) is then advanced to the heart through the needle lumen. After gaining access to the pericardial space, the operator removes the Tuohy-needle then advances and secures a sheath (for example, <NUM>. 5Fr) to facilitate use of treatment devices such as ablation and mapping catheters.

Mechanical puncture using large bore needles, as described above, is associated with a high clinical complication rate. Although the stiff needle provides some stability and some tactile feedback to the user, unwanted tissue damage is possible if the needle inadvertently punctures or unintentionally lacerates tissue.

As a consequence of the challenges and uncertainties of using mechanical puncture for accessing the pericardial space, physicians may resort to common endocardial ablation in situations where epicardial ablation is a preferred treatment, such as ventricular tachycardias. New devices or methods to improve the safety and predictability of gaining access to the pericardial space would be of benefit.

The problem of improving the ease of use, safety, and predictability of gaining access to the epicardium is solved, at least in part, by a needle for gaining epicardial access, the needle having an elongate member (e.g. a main shaft) defining a lumen and a side-port in communication with the lumen; a blunt atraumatic tip for delivering energy for puncturing tissue; and a guiding surface (e.g. a ramp) for directing a device (e.g. a guidewire) through the side-port.

The present inventors have conceived, and reduced to practice, embodiments of such a medical device. Some embodiments of the needle have a blunt tip of <NUM>, <NUM><NUM>, or <NUM> Ga. The blunt tip prevents any premature mechanical puncture to the pericardium when pressed against it. Also, a needle with a blunt tip provides better tactile feedback than a needle with a sharp tip. The side-port allows delivery of contrast agent and facilitates deployment of a device (e.g. a guidewire) through the needle to confirm access to the pericardial space. Physicians typically use fluoroscopy to check that the guidewire (or other device) is wrapped around the heart to confirm pericardial access. Physicians may also confirm access via tactile feedback which may indicate incorrect needle position or obstruction. Physicians may also deliver contrast medium to confirm access and determine needle location.

In one broad aspect, embodiments of the present invention comprise a needle for gaining access to the pericardial cavity of a heart, the needle having a blunt tip for delivering energy for puncturing, and a side-port for confirming, gaining, or facilitating epicardial access.

As a feature of this aspect, the needle comprises a guiding surface feature (e.g. a ramp) within the side-port configured to guide the guidewire (or other device) out the side of the needle and in a forward direction. Some embodiments of the guiding surface have a generally S-shaped surface.

In a second broad aspect, embodiments of the present invention comprise a needle for gaining epicardial access, the needle comprising: an elongate member defining a lumen and a side-port in communication with the lumen; a blunt tip for delivering energy for puncturing tissue; and a guiding surface for directing a device through the side-port. In some embodiments, the elongate member is comprised of a metal, and the needle further comprises an insulation covering outside of the elongate member, with the blunt tip being electrically exposed to define an electrode, wherein the needle is operable for delivering energy through a metal side wall of elongate member to the electrode. In some such embodiments, the electrode has greater radiopacity than the elongate member. Some embodiments of this broad aspect include an insulation portion covering a proximal part of the side-port to define an aperture, with the insulation portion being configured to reduce abrasive friction between the device and a proximal edge of the side-port as the device travels through the side-port.

As features of the second broad aspect, some embodiments further comprise insulation on an inner surface of the elongate member adjacent to the side-port to reduce electrical leakage, with some embodiments further comprising insulation on the inner surface of most or substantially all the elongate member to reduce electrical leakage, and some embodiments including a part of the elongate member adjacent and distal of the side-port being electrically exposed to define an elongate member exposed portion.

As features of the second broad aspect, some embodiments include the lumen terminating at the side-port. Some embodiments include a single side-port operable for the device to travel therethrough. In some embodiments, the side-port is capsule-shaped. Some examples have a distal edge of the side-port including a bevel, and in some such examples, the bevel includes a combination of rounded and flat portions.

Some embodiments of the needle comprise a distal edge of the side-port being located at a distance of about <NUM> to <NUM> inches (about <NUM> to <NUM>) from an electrode distal tip, and in some such embodiments, the distal edge of the side-port is located at a distance of about <NUM> inches (about <NUM>) from the electrode distal tip.

As features of the second broad aspect, some embodiments include a proximal edge of the side-port being beveled; the guiding surface having a generally S-shaped surface; and an insulation portion covering a proximal part of the side-port and a distal end of the guiding surface being beveled, whereby the device is guided out of a side of the needle and in a forward direction when advanced out of the side-port.

An explanatory method is disclosed for accessing a pericardial cavity, the method comprising the steps of: (<NUM>) contacting a pericardium with a needle, (<NUM>) tenting the pericardium with the needle and delivering energy through a blunt tip of the needle, (<NUM>) puncturing the pericardium with the needle and injecting a contrast flow into a pericardial cavity through a side-port of the needle, (<NUM>) advancing a guidewire through the needle and into the pericardial cavity, and (<NUM>) withdrawing the needle while leaving the guidewire in the pericardial cavity.

An explanatory method is disclosed for accessing a pericardial cavity, the method comprising the steps of: (<NUM>) contacting a pericardium with a needle, (<NUM>) tenting the pericardium with the needle and delivering energy through a blunt tip of the needle, (<NUM>) puncturing the pericardium with the needle and injecting a contrast flow into a pericardial cavity through a side-port of the needle, (<NUM>) advancing a small diameter guidewire into the pericardial cavity, (<NUM>) withdrawing the needle and advancing a dilator to dilate the puncture through the pericardium, (<NUM>) advancing a sheath over the dilator into pericardial cavity, (<NUM>) withdrawing the small diameter guidewire and advancing a relatively larger guidewire into the pericardial cavity, and (<NUM>) withdrawing the sheath.

A further explanatory method is disclosed having the steps of contacting a pericardium with a needle, using the needle for tenting the pericardium and delivering energy, using the needle for puncturing the pericardium and injecting a contrast flow into a pericardial cavity, advancing a guidewire (or other device) through the needle and into the pericardial cavity, and withdrawing the needle while leaving the guidewire (or other device) in the pericardial cavity.

As features of this aspect, some explanatory methods disclosed further include the steps of advancing a mapping catheter or some other diagnostic device, and/or advancing an ablation catheter or some other treatment device, and/or placing leads or other medical devices.

With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of certain embodiments of the present invention only.

<FIG> shows a top view of a needle <NUM> having a side-port <NUM> in elongate member <NUM>. <FIG> shows a side view of the same needle with a guidewire <NUM> extending out of side-port <NUM>. The side-port of <FIG> is a slotted hole. The dimensions of the slot are dependent on the needle gauge and guidewire outer diameter. Some embodiments of needle <NUM> are 17Ga, have a side-port width of about <NUM> inches (about <NUM>), a radius of about <NUM> inches (about <NUM>), a slot length of about <NUM> inches (about <NUM>), and can accommodate deployment and retraction of a <NUM> inches (about <NUM>) guidewire, and of guidewires having a smaller outer diameter. Such an embodiment may also accommodate, with a smaller clearance, a guidewire with an outer diameter of <NUM> inches (about <NUM>). Guidewires used in the disclosed method are typically comprised of spring stainless steel. In some embodiments, the distal tip of the guidewire is made of nitinol to provide a softer tip than steel. Some alternative embodiments comprise an insulated guidewire having a lubricous coating on the insulation. Embodiments of needle <NUM> typically have only a single side-port operable for advancing a guidewire (or other device) therethrough.

While this disclosure, for explanatory purposes, focuses on the use of needle <NUM> with guidewires, other devices can be advanced through needle, for example, flexible devices operable to delivery energy or monitor physiological variables.

The embodiment of the side-port <NUM> of <FIG> is a rounded slot or a slotted hole (i.e. capsule-shaped) having a constant side-port width. This configuration provides a flat wall with a minimal edge profile, thereby reducing the potential for generating debris when deploying or retracting a guidewire. Typically, side-port <NUM> and guidewire <NUM> are configured such that the clearance of the side-port <NUM> from the guidewire will be at least about <NUM> inches (about <NUM>). If using a smaller outer diameter guidewire, the clearance will be greater.

Detail A-V1 and detail A-V2 show alternative views for cut-away line A-A of <FIG>. Details A-V1 and A-V2 illustrate a guiding surface <NUM> (or ramp) within side-port <NUM>, which functions to guide an advancing guidewire <NUM> through side-port <NUM>. The guiding surface embodiment may be straight (e.g. detail A-V1) or curved (e.g. detail A-V2). The portion of guiding surface <NUM> visible from external sideview (from outside of the needle) has a length of about <NUM> inches (about <NUM>) for the embodiment of <FIG>. Please note, that while not all of the figures show a layer of insulation since it is not necessary for an understanding of the features illustrated by those figures, typical embodiments of needle <NUM> include insulation.

Guidewire <NUM> is placed under a bending moment when exiting the side port. To reduce this force, a bevel <NUM> (shown in <FIG>) is located at the distal edge of side-port <NUM>. In some embodiments, a bevel <NUM> of <NUM> degrees is located about <NUM> inches (about <NUM>) from the distal edge of side-port <NUM>. Some such embodiments have been shown to be effective in reducing the bending moment. In some embodiments the bevel is generally flat, while in other embodiments the bevel is rounded, and in yet further embodiments the bevel includes a combination of rounded and flat portions.

<FIG> is a cut-away view including distal tip <NUM> of needle <NUM>, wherein elongate member <NUM> defines lumen <NUM>, guiding surface <NUM>, and side-port <NUM>. The embodiment of guiding surface <NUM> of <FIG> has a generally S-shaped surface. In general, side-port <NUM> is located close to the distal tip of the needle, which is advantageous for confirming the position of distal tip <NUM> because it allows contrast fluid to be delivered close to the needle's tip. In contrast, a device having a side-port that is relatively further away from the tip is more likely to encounter a situation where the side-port is still covered by tissue even though the distal tip has punctured a layer of tissue. A side-port <NUM> located close to the distal tip, in combination with the previously described bevel <NUM>, also allows for a curved or 'J' tip wire extended through side-port <NUM> to travel a short distance forward before curving, which prevents potential piercing of the epicardium with the wire tip. While a curved tip wire that easily bends or is floppy at the distal tip is advantageous for reducing unwanted tissue trauma, needle <NUM> may also be used with guidewire having a straight tip.

<FIG> is a cross-section showing a guidewire <NUM> that has been advanced through the lumen <NUM> and the side-port of needle <NUM>. Enlarged sections C1 and C2 show guidewire <NUM> in contact with two different embodiments of the proximal edge <NUM> of side-port <NUM>. Enlarged section C1 includes a proximal edge <NUM> having an approximately <NUM>° angle. This angle is sharp enough to scrape a guide-wire as it is advanced or retracted through the side-port, which may result in some debris creation. It is advantageous for proximal edge <NUM> to be beveled (as shown, for example, in enlarged section C2) to reduce debris generation when translating the guidewire through the needle. Some embodiments include a straight beveled edge or a rounded bevel located about <NUM> inches (about <NUM>) from a proximal edge <NUM>. In some such embodiments, these bevels have proven effective in reducing debris formation.

<FIG> illustrates needle <NUM> with insulation <NUM> (typically a polymer) covering the needle shaft, leaving an area around side-port <NUM> exposed, and a distal tip area exposed to define an electrode <NUM> which may be used for channeling into and puncturing tissue. In some alternative embodiments, insulation <NUM> is a ceramic.

Typical embodiments of needle <NUM> have a elongate member <NUM> (i.e. a main shaft) comprised of <NUM>, <NUM> or <NUM> stainless steel, and an electrode <NUM> comprised of the same steel as the elongate member <NUM>, with electrode <NUM> being dome welded. Alternative embodiments of elongate member <NUM> are comprised of other metals, including copper, titanium and nickel-titanium alloys, amongst others. In typical embodiments, energy (e.g. electricity) is delivered to electrode <NUM> through the metal side wall of needle <NUM>. In some alternative embodiments, the needle's elongate member <NUM> is comprised of a stiff polymer and electrical energy is delivered to electrode <NUM> through an electrically conductive wire. Some alternative embodiments have an electrode <NUM> comprised, at least in part, of material more radiopaque than the elongate member such as platinum, platinum and Iridium alloys, gold, or silver to provide radiopaque visibility under fluoroscopy to determine the location of the needle's tip (i.e. the electrode has greater radiopacity than the elongate member). Such materials also improve reduction potential when collecting ECG data. Round tipped electrodes and the use of such round tipped electrodes for cutting tissue is described in <CIT>.

In one specific embodiment of needle <NUM>, side-port <NUM> in elongate member <NUM> has a length of about <NUM> inches (about <NUM>), the distance between side-port <NUM> and electrode <NUM> is about <NUM> inches (about <NUM>), electrode <NUM> has a hemispherical shape with a radius of about <NUM> inches (about <NUM>), whereby distal tip <NUM> of needle <NUM> has an outer diameter of about <NUM> inches (about <NUM>), and there is distance of about <NUM> inches (about <NUM>) between electrode distal tip <NUM> (<FIG>) and side-port <NUM>. In alternative embodiments, the distance between side-port <NUM> and electrode <NUM> is about <NUM> to <NUM> times the outer diameter of the needle tip; the length of side-port <NUM> depends on the inner diameter of the needle and the outer diameter of the an intended guide-wire, and ranges from about <NUM> to <NUM> inches, or about <NUM> to <NUM> (about the equivalent of <NUM> to <NUM> times the outer diameter of a <NUM> inch (about <NUM>) guidewire); the distance between electrode distal tip <NUM> and side-port <NUM> ranges from about about <NUM> to <NUM> inches (about <NUM> to <NUM>); and the electrode <NUM> has a size of about <NUM> to <NUM> Gauge (about <NUM> inches (about <NUM>) to about <NUM> inches (about <NUM>)). The electrode is large enough to provide bumper support against heart tissue.

<FIG> also illustrates insulation portion 32a, which covers a proximal part of side-port <NUM> to define an aperture <NUM> having a length of about <NUM> inches (about <NUM>). Aperture <NUM> is smaller than side-port <NUM> (uncovered). If contrast fluid is delivered through needle <NUM> under a constant lumen fluid pressure, the contrast will expel in a narrower stream and closer to the distal tip through an aperture <NUM> than through a relatively longer side-port <NUM>.

Insulation portion 32a also reduces the amount of abrasive friction between guidewire <NUM> and proximal edge <NUM> of the side-port. First, while guidewire <NUM> can still rub against proximal edge <NUM> as it travels through the side-port, insulation portion 32a reduces the frictional forces between the guidewire and proximal edge <NUM>. Second, when guidewire <NUM> travels through the side-port, it glides over insulation portion 32a, which is comprised of a polymer that is softer and less abrasive than the metal of the proximal edge <NUM>. Insulation portion 32a further functions to direct an advancing guidewire forward, as to be further explained below.

In addition, insulation portion 32a reduces electrical leakage through side-port <NUM>. In typical embodiments of needle <NUM> the tubular metal shaft tube is not insulated, which allows some electricity to leak out of the metal immediately adjacent to the side-port (i.e. metal forming the edge of the side-port), and some electricity to leak through fluid within the lumen and out of side-port <NUM>. Insulation portion 32a covers some of the metal immediately adjacent the side-port to reduce electrical leakage therefrom. Insulation portion 32a also reduces the amount of fluid inside the lumen that is exposed to the environment outside the needle, thereby reducing electrical leakage through the fluid. Some alternative embodiments of needle <NUM> include insulation on an inner surface of the metal shaft tube in the area of the side-port (i.e. adjacent to) to reduce electrical leakage. Some other alternative embodiments include insulation on an inner surface of most or substantially all the metal shaft tube to reduce electrical leakage.

Another feature of needle <NUM> illustrated in <FIG> is that insulation <NUM> leaves a part of needle <NUM> adjacent to side-port <NUM> exposed to define elongate member exposed portion 20a. Another way to describe elongate member exposed portion 20a is that insulation <NUM> is trimmed back from the distal edge of side-port <NUM> to reduce the profile (or surface area) of the distal face of side-port <NUM>. A reduced profile for the distal face allows a guidewire to exit the side-port at a reduced angle, i.e., closer to needle <NUM>. Furthermore, including elongate member exposed portion 20a may help avoid a metallic guidewire adhering to insulation immediately adjacent to the side-port if a physician inadvertently electrifies the guidewire.

<FIG> illustrates an embodiment of needle <NUM> having a lubricious coating to enhance tactile feedback. <FIG> show some of the uses of needle <NUM>. <FIG> illustrates a guidewire <NUM> that has been advanced out of the side-port and is being advanced forwards. Guidewire <NUM> is guided forward by insulation portion 32a and bevel <NUM> of guiding surface <NUM>. In more detail, the insulation portion 32a covers a proximal part of the side-port and a distal end of the guiding surface (or ramp) is beveled, whereby a device (e.g. a guidewire) is guided out of a side of the needle and in a forward direction when advanced out of the side-port. <FIG> illustrates contrast fluid injected using the side-port to create a contrast flow <NUM>. <FIG> illustrates that a blunt tip comprised of electrode <NUM> can be used for ECG monitoring and recording. <FIG>, consisting of <FIG>, illustrates some monitoring situations and the associated ECG signals. <FIG>, consisting of <FIG>, shows ECG readings for different locations of the distal tip <NUM> of needle <NUM> within a pig to illustrate the advantage of ECG usage in identifying a puncture of a pericardium.

One explanatory method to fabricate a distal portion of a needle having the described geometry is to weld a metal billet, placed inside the needle lumen and flush with the needle's distal tip, to the distal end of the needle's metal shaft. The metal billet has a prefabricated guiding surface produced using milling or electrical discharge machining (EDM), and the needle shaft has a prefabricated side-port.

Another explanatory method to fabricate a distal portion of a needle is to first weld a solid metal billet flush with the distal tip of the needle's shaft, and then form the side port slot and guiding surface with an EDM electrode having a geometry corresponding to the side port and guiding surface.

<FIG> is an illustration showing an eight step explanatory method of using five devices, including a needle <NUM> disclosed herein. <FIG> shows a step <NUM> of contacting a pericardium <NUM> with needle <NUM>. The heart is typically approached using a subxiphoid approach. Step <NUM> (<FIG>) includes tenting pericardium <NUM> with the needle and delivering energy (shown in broken line) through the blunt tip of needle <NUM>. Step <NUM> (<FIG>) includes puncturing the pericardium <NUM> with the needle and injecting a contrast flow <NUM> into pericardial cavity <NUM> through a side-port of needle <NUM>. In this example of the method, needle <NUM> is not touching myocardium <NUM>, while in alternative embodiments, needle <NUM> touches but does not tent the myocardium <NUM>. <FIG> illustrates step <NUM>, advancing a small diameter guidewire <NUM> through the side-port and into the pericardial cavity <NUM>. After the small diameter guidewire <NUM> is advanced, the method further includes a step <NUM> (<FIG>) of withdrawing needle <NUM> and advancing dilator <NUM> to dilate the puncture through pericardium <NUM>. Sheath <NUM> may be advanced with dilator <NUM> or the sheath may be advanced afterwards to arrive at the illustration of <FIG>. Once the puncture is dilated, the method includes step <NUM> of advancing sheath <NUM> over the dilator into pericardial cavity <NUM> to arrive at the illustration of <FIG>. Step <NUM> includes withdrawing small diameter guidewire <NUM> and advancing guidewire <NUM> into pericardial cavity <NUM> (<FIG>). Step <NUM> (<FIG>) includes withdrawing the sheath, and leaving the guidewire <NUM> in pericardial cavity <NUM>. In some embodiments guidewire <NUM> has a diameter of about <NUM> inches (about <NUM>) and small diameter guidewire <NUM> has a diameter of about <NUM> inches (about <NUM>). In some alternative embodiments, small diameter guidewire <NUM> has a diameter smaller than <NUM> inches (about <NUM>). Once guidewire <NUM> has been advanced into pericardial cavity <NUM> to provide access, other steps may include advancing a mapping catheter or some other diagnostic device, advancing an ablation catheter or some other treatment device, or placing leads or other medical devices.

<FIG> is an illustration showing a five step explanatory method of using two devices, needle <NUM> and guidewire <NUM>. Step <NUM> (<FIG>) includes contacting a pericardium <NUM> using needle <NUM>. Step <NUM> (<FIG>) includes tenting pericardium <NUM> with the needle and delivering energy (shown in broken line) through the blunt tip of needle <NUM>. Step <NUM> (<FIG>) includes puncturing the pericardium <NUM> with the needle and injecting a contrast flow <NUM> into pericardial cavity <NUM> through a side-port of needle <NUM>. <FIG> illustrates a step <NUM> of advancing a guidewire <NUM> through the needle and into pericardial cavity <NUM>. After the guidewire <NUM> is advanced, the method further includes a step <NUM> of withdrawing needle <NUM> while leaving guidewire <NUM> in pericardial cavity <NUM> to arrive at the illustration of <FIG>. In some embodiments guidewire <NUM> has a diameter of about <NUM> inches (about <NUM>). As with the above method, once guidewire <NUM> has been advanced into pericardial cavity <NUM> to provide access, other steps may include advancing a mapping catheter or some other diagnostic device, advancing an ablation catheter or some other treatment device, or placing leads or other medical devices for example at the epicardium. Guidewire used in the two above described methods may have a straight tip or a curved tip.

The embodiments of the invention described above are intended to be exemplary only. The scope of the invention is therefore intended to be limited solely by the scope of the appended claims.

Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination.

Claim 1:
A needle (<NUM>) for gaining epicardial access, the needle (<NUM>) comprising: an elongate member defining a lumen (<NUM>) and a side-port (<NUM>) in communication with the lumen (<NUM>) wherein the elongate member is comprised of a metal; a blunt tip for delivering energy for puncturing tissue wherein the blunt tip of the needle (<NUM>) is electrically exposed to define an electrode (<NUM>); and a guiding surface (<NUM>) for directing a device through the side-port (<NUM>),
characterized in that the needle further includes an insulation (<NUM>) a portion of which covers an outside of the elongate member as an insulation portion (32a), and which covers a proximal part of the side-port (<NUM>) to define an aperture (<NUM>), the insulation portion (32a) configured to reduce abrasive friction between the device and a proximal edge of the side-port (<NUM>) as the device travels through the side-port (<NUM>).