Patent Description:
Cannula and electrode assemblies are known and have been used for some time for tissue ablation. Among these are cannula and electrode assemblies in which the cannula is provided with a side opening a short distance away from the distal tip of the cannula through which the electrode is guided such that the distal tip of the electrode extends out of the side opening. When current is supplied to such an assembly, ablation current flows through a volume larger than would otherwise be affected by an assembly in which the electrode extends out of the distal end of the cannula.

<CIT> discloses an RF electrode having a straight shaft to generate an RF heat lesion that is asymmetric about the central axis of the cannula through which the RF electrode is introduced into bodily tissue. An electrode can be inserted into a cannula, and an electrosurgical generator can apply current between the active tip of the electrode and the active tip of the cannula to heat tissue.

<CIT> discloses an ablation element that comprises an elongated cannula having a proximal end and a distal end and defines an internal lumen within the cannula and a cannula axis; a plurality of ablation stylets that each have a proximal end and a distal end, and each coupled at the respective proximal end of the stylet to the distal end of a respective conductor; and a trocar point defined proximate the distal end of the cannula with a deflection surface positioned between the trocar point and the proximal end of the cannula, the deflection surface being configured and positioned to deflect, in response to axial movement of the stylets in a direction from the proximate end of the cannula to the distal end of the cannula, at least some of the stylets laterally with respect to the cannula axis in different directions along substantially straight paths, the paths defining an ablation volume.

The present invention relates to a cannula that comprises (a) a cannula tube comprising a proximal end, a distal end, a cannula tube lumen, a sidewall, and a sidewall opening extending through the sidewall, the sidewall opening having a proximal end and distal end and (b) a cannula tip secured to the distal end of the cannula tube, the cannula tip comprising a proximal tip portion that is inserted into the cannula tube lumen and a distal tip portion that extends beyond the distal end of the cannula tube, the cannula tip being configured to allow fluid to flow therethrough, wherein the proximal tip portion of the cannula tip comprises a ramp at a proximal end thereof, wherein the ramp is configured to eject a distal tip of an elongated device through the sidewall opening of the cannula tune as the elongated device is inserted through the cannula tube from the proximal end of the cannula tube.

In some embodiments, the cannula tip is secured to the cannula tube by a weld.

In some embodiments, which can be used in conjunction of any of the above aspects and embodiments, the distal end of sidewall opening is beveled.

In some embodiments, which can be used in conjunction of any of the above aspects and embodiments, the sidewall opening extends around a circumference of the cannula tube by and angle ranging from <NUM> to <NUM> degrees,.

In some embodiments, which can be used in conjunction of any of the above aspects and embodiments, the cannula tube is bent at proximal end of the sidewall opening by an angle ranging from <NUM> to <NUM> degrees.

In some embodiments, which can be used in conjunction of any of the above aspects and embodiments, the proximal tip portion has a first outer diameter and the distal tip portion has a second outer diameter that is larger than the first outer diameter, and there is a step-up in diameter between the proximal tip portion and the distal tip portion such that the proximal tip portion is inserted into a distal end of the cannula tube and such that the proximal end of the distal tip portion abuts the distal end of the cannula tube portion.

In some embodiments, which can be used in conjunction of any of the above aspects and embodiments, the distal tip portion has an outer diameter that is the same as an outer diameter of the cannula tube.

In some embodiments, which can be used in conjunction of any of the above aspects and embodiments, the cannula tip comprises a lumen that allows fluid to flow therethrough, a channel that allows fluid to flow therethrough, a slot that allows fluid to flow therethrough, a combination of a lumen and a slot that allow fluid to flow therethrough, a combination of a lumen and a channel that allow fluid to flow therethrough, a combination of a channel and a slot that allow fluid to flow therethrough, or a combination of a lumen, a channel and a slot that allow fluid to flow therethrough.

In some embodiments, which can be used in conjunction of any of the above aspects and embodiments, the proximal tip portion comprises a slot and the distal tip portion comprises a distal tip lumen in fluid communication with the slot.

In some embodiments, which can be used in conjunction of any of the above aspects and embodiments, the ramp has a proximal end and a distal end. In some of these embodiments, the slot bisects the ramp and/or the distal end of the ramp terminates proximal to the distal end of the sidewall opening.

In some embodiments, which can be used in conjunction of any of the above aspects and embodiments, the slot does not extend to the distal end of the proximal tip portion.

In some embodiments, which can be used in conjunction of any of the above aspects and embodiments, the distal end of the slot comprises a circular recess that is axially aligned with and has same diameter as the distal tip lumen.

In some embodiments, which can be used in conjunction of any of the above aspects and embodiments, the cannula further comprises a hub that is attached to the proximal end of the cannula tube.

In some aspects, the present disclosure further provides a system that comprises: (a) a cannula in accordance with any of the above aspects and embodiments and (b) an electrode having a distal electrode tip, wherein the electrode is configured to be inserted into a proximal end of the cannula and through the cannula tube, and wherein the cannula tip is configured to eject the distal electrode tip through the sidewall opening of the cannula tube as the electrode is inserted through the cannula tube from the proximal end of the cannula. In some embodiments, the distal electrode tip is rounded.

In some aspects, the present disclosure further provides an assembly that comprises: (a) a cannula in accordance with any of the above aspects and embodiments and (b) a stylet having a stylet tip, wherein the stylet is configured to be inserted into a proximal end of the cannula and through the cannula tube such that the stylet tip is proximate the sidewall opening when fully inserted.

In some embodiments, the cannula further comprises a hub that is attached to the proximal end of the cannula tube, wherein the stylet comprises a stylet cap that is attached to a proximal end of the stylet. In some of these embodiments, the stylet cap engages the cannula hub.

These and other aspects, embodiments and advantages of the present disclosure will become immediately apparent to those of ordinary skill in the art upon review of the detailed description and claims to follow.

As discussed in more detail below, in one aspect, the present disclosure pertains to cannulas that are useful for guiding an elongated internal device such that the elongated internal device is ejected through a sidewall opening in the cannulas instead of extending through a distal end of the cannulas. In various embodiments described herein, the elongated internal device is an RF electrode. However, it should be understood that the cannulas described herein may be used in systems that include internal devices other than RF electrodes.

Cannulas in accordance with the present disclosure include (a) a cannula tube comprising a proximal end, a distal end, a cannula tube lumen, a sidewall and a sidewall opening extending through the sidewall and (b) a cannula tip secured to a distal end of the cannula tube, the cannula tip having proximal tip portion that is inserted into the cannula tube lumen and a distal tip portion extending beyond the distal end of the cannula tube. The cannula tip is configured to allow fluid to flow through the cannula tip and is also configured to eject a distal tip of an elongated device (e.g., an electrode) through the sidewall opening as the device is inserted through the cannula tube from a proximal end of the cannula tube. In this way, the cannulas of the present disclosure allow fluid that is injected though the lumen of the cannula tube to be dispensed from a distal end of the cannula while at the same time disallowing the electrode from proceeding past the side port to the distal end of the cannula.

With reference now to the drawings, a cannula <NUM> in accordance with the present disclosure is shown in <FIG>. The cannula shown in <FIG> is formed from a cannula tube <NUM> as shown in <FIG> and a cannula tip <NUM> as shown in <FIG>. A variety of materials may be used to form the cannula tube <NUM> and cannula tip <NUM>, including various metallic and polymer materials.

Turning now to <FIG> (also seen, for example, in <FIG>), a distal portion of a cannula tube <NUM> in accordance with an embodiment of the present disclosure is schematically illustrated therein. The cannula tube <NUM> includes a cannula tube lumen <NUM>, a sidewall <NUM>, and a sidewall opening 110o having a proximal end 110op and distal end 110od. The outer diameter of the cannula tube will vary widely, depending on the application, and may range, for example, between <NUM> gauge (<NUM>) and <NUM> gauge (<NUM>), among other values. The thickness of the sidewall <NUM> and the diameter of the inner lumen <NUM> will depend on the gauge selected. Typically sidewall <NUM> thickness may range from <NUM> (e.g., for a <NUM> gauge regular wall) to <NUM> (e.g., for a <NUM> gauge thin wall), among other values. Typically, the diameter of the inner lumen <NUM> ranges may range from <NUM> (e.g., for a <NUM> gauge regular wall) to <NUM> (e.g., for a <NUM> gauge thin wall), among other values. The length 110ol of the sidewall opening will also vary depending on the gauge selected. In some embodiments, the length 110ol of the sidewall opening may range, for example, from <NUM> to <NUM>, for example <NUM> (based on a <NUM> gauge prototype) to <NUM> (based on a <NUM> gauge prototype), among other values.

The sidewall opening 110o will extend around a circumference of the cannula tube <NUM> by various angles 110oa, extending, for example, from <NUM> to <NUM> degrees, preferably from <NUM> to <NUM> degrees, more preferably from <NUM> to <NUM> degrees, around a circumference of the cannula tube <NUM>, among other values.

The sidewall opening 110o may be formed by any suitable process, including machining, wire EDM, grinding, or laser cutting. Once formed, the edges of the sidewall opening 110o may be beveled via grinding and/or an electropolishing process. In various embodiments, the distal end 110od of the sidewall opening 110o may be provided with a bevel angle that matches an angle of a ramp of the cannula tip <NUM> (described below).

In certain embodiments, a distal end of the cannula tube <NUM> may be bent at an angle 110a (see <FIG>) to assist with the expulsion of the electrode. For example, the cannula tube <NUM> may be bent at an angle 110a ranging, from <NUM> to <NUM> degrees, typically ranging from <NUM> to <NUM> degrees, among other values.

In particular embodiments, the materials for cannula tube <NUM> may be formed from metallic materials including iron-chromium alloys, such as stainless steel, nickel-titanium alloys, such as nitinol, and nickel-chromium alloys, such as inconel.

Turning now to <FIG> (see also <FIG>), a cannula tip <NUM> in accordance with an embodiment of the present disclosure is schematically illustrated. The cannula tip <NUM> has a proximal end 110p and a distal end 110d. The cannula tip <NUM> is configured to allow fluid flow therethough as discussed in more detail below. The cannula tip <NUM> also comprises a ramp <NUM> at a proximal portion 120p thereof that is configured to assist with expelling an internal device such as an electrode from the sidewall opening 110o of the cannula <NUM>, by nudging a tip of the electrode in a direction of the sidewall opening 110o. In certain embodiments, a proximal face of the ramp is provided with a ramp angle 122a (see <FIG>) relative to a longitudinal axis of the cannula tip <NUM>. For example, the ramp <NUM> may be provided with a ramp angle 122a ranging, for example, from <NUM> to <NUM> degrees, typically ranging from <NUM> to <NUM> degrees, among other values.

Moreover, the cannula tip <NUM> typically comprises a bevel <NUM> at a distal tip thereof that is configured to enhance the ability of the cannula <NUM> to pierce tissue.

In particular embodiments, the materials for cannula tip <NUM> may be formed from metallic materials including iron-chromium alloys such as stainless steel, nickel-titanium alloys such as nitinol, and nickel-chromium alloys such as inconel.

As seen from <FIG>, upon assembly of the cannula tube <NUM> and the cannula tip <NUM>, the distal end 110od of the sidewall opening 110o will be a predetermined distance 100d from the distal-most tip of the cannula tip <NUM>. In some embodiments, the distance 100d may range from <NUM> to <NUM>.

In the embodiment shown, the cannula tip <NUM> mates with the distal tip 110dt of the cannula tube <NUM>. In order to provide this feature, a proximal portion 120p of the cannula tip <NUM> is formed such that a diameter of the proximal portion 120p is less than an inner diameter of the cannula tube <NUM> (i.e., the diameter of the lumen <NUM>) at a distal end of the cannula tube 110d, such that that the proximal portion 120p of the cannula tip <NUM> can be inserted into the distal end 110d of the cannula tube <NUM>.

In various embodiments, a distal portion 120d of the cannula tip <NUM> is formed with a diameter that is greater than an inner diameter of the cannula tube <NUM> (i.e., the diameter of the lumen <NUM>) at a distal end 110d of the cannula tube <NUM>. In other words, there is a step-up in the diameter of the cannula tip <NUM> at a point where the distal portion 120d of the cannula tip <NUM> transitions to the proximal portion 120p of the cannula tip <NUM>. In this way, the proximal portion 120p of the cannula tip <NUM> can be inserted into the distal 120d of cannula tube <NUM>, but only to a point where a proximal tip 120dp of the distal portion 120d of the cannula tip <NUM> abuts the distal tip 110dt of the cannula tube <NUM>. In various embodiments, an outer diameter at the proximal tip 120dp of the distal portion 120d matches an outer diameter of the cannula tube <NUM> at a distal tip 110dt of the cannula tube <NUM>.

The cannula tip <NUM> may be secured to the distal end 110d of the cannula tube <NUM> by a variety of methods including, for example, by welding (e.g., laser welding) by friction fit, of by use of a suitable adhesive, among other methods.

As previously noted, in various embodiments, cannulas <NUM> in accordance with the present disclosure are configured are configured to allow fluid to flow therethough, such that fluid flows from a distal end of the cannulas <NUM>. As an initial matter, it is noted that in order to provide the cannulas described herein with this feature, some mechanism must be provided to allow for fluid to flow through and/or around the cannula tip <NUM>. The present inventors have developed various strategies for providing the cannulas described herein with this feature, including lumens, channels, slots, and combination of these features.

For example, referring to <FIG>, in one embodiment, a cannula tip <NUM> is provided having a lumen <NUM> extending therethrough. Although the lumen <NUM> shown has an increase in diameter between the proximal portion 120p of the cannula tip <NUM> and the distal portion 120d of the cannula tip <NUM>, other designs are possible in which the lumen <NUM> decreases in diameter between the proximal portion 120p of the cannula tip 120and the distal portion 120d of the cannula tip <NUM>, or in which the lumen <NUM> is of constant diameter within the proximal portion 120p of the cannula tip 120and the distal portion 120d of the cannula tip <NUM>.

As another example, as seen in <FIG>, a cannula tip <NUM> may be provided that has a channel 120c extending along the proximal portion 120p of the cannula tip 120and the distal portion 120d of the cannula tip <NUM>.

As another example, as seen in <FIG>, a cannula tip <NUM> may be provided that has a channel 120c within the proximal portion 120p of the cannula tip <NUM> and a lumen <NUM> within the distal portion 120d of the cannula tip <NUM>.

In other embodiments shown in <FIG>, <FIG> and <FIG>, a cannula tip <NUM> may be provided having a slot <NUM> within the proximal portion 120p of the cannula tip <NUM> and a lumen 120ld in the distal portion 120p of the cannula tip <NUM>. It is noted that the slot <NUM> in <FIG> extends along the entire length of the proximal portion 120p of the cannula tip <NUM> (i.e., all the way to the proximal tip 120dp of the distal portion 120d of the cannula tip <NUM> where there is a step-up in the diameter of the cannula tip <NUM>).

In <FIG>, <FIG>, on the other hand, the slot <NUM> does not extend all the way to the proximal tip 120dp of the distal portion 120d (i.e., the slot <NUM> terminates at a point proximal to the step-up in the diameter of the cannula tip <NUM>). Consequently, the proximal portion 120p of the cannula tip <NUM> contains a section of lumen 120lp, which opens into the slot <NUM> and which is an extension of the lumen 120ld in the distal portion 120p of the cannula tip <NUM>. In other embodiments (not shown), the slot <NUM> may only extend the axial length of the ramp <NUM>. A potential advantage of terminating the slot <NUM> at a point proximal to the step-up in the diameter of the cannula tip <NUM> is that potential issues may be avoided that can arise when the cannula tip <NUM> is welded to the cannula tube <NUM>.

As can be further seen from <FIG> and <FIG>, in the design shown, a circular recess 120r is formed at the distal end of the slot <NUM>, which is is axially aligned with and has same diameter as the lumen 120lp/120ld.

In certain embodiments, cannula tips <NUM> in accordance with the present disclosure can be machined from a solid rod of material, for example, by drilling a hole in a distal end of the material, forming a bevel in the distal end of the material, reducing a diameter of the proximal end of the material, grinding a ramp in the proximal end of the material, and forming a slot in the proximal end of the material.

As can be seen, for example, from <FIG>, <FIG> and <FIG>, a length of the proximal portion 120p of the cannula tip <NUM> is beneficially dimensioned such that, upon insertion of the proximal portion 120p of the cannula tip <NUM> into the distal end 110d of the cannula tube <NUM>, the ramp <NUM> is positioned such that a distal end 122d of the ramp <NUM> lies at or just proximal to the distal end 110od of the sidewall opening 110o (see, e.g., <FIG>). Moreover, as noted above, the distal end 110od of the sidewall opening 110o may be beveled at an angle that approximately matches the angle of the ramp <NUM>, in certain beneficial embodiments.

Turning now to <FIG>, in various embodiments, cannulas <NUM> in accordance with the present disclosure may be provided with a cannula hub <NUM>, which is attached to a proximal end 110p of the cannula tube <NUM>. In various embodiments, an assembly <NUM> may be provided which further includes a stylet <NUM> having a stylet cap <NUM>. The stylet <NUM> may be inserted into the cannula hub <NUM> and cannula tube <NUM> of a cannula <NUM> in accordance with the present disclosure. Moreover the stylet cap <NUM> can be configured to engage with the cannula hub <NUM> as shown. Materials for forming the stylet cap <NUM> and cannula hub <NUM> include any suitable material, with plastics, for example, acrylic polymers and polycarbonate being particularly beneficial in some embodiments. Materials for forming the stylet <NUM> include polypropylene, polycarbonate, acrylonitrile butadiene styrene (ABS), and ABS/polycarbonate blends. The stylet <NUM> can provide structural rigidity to the cannula <NUM> during insertion into a patient. Moreover, by having a distal tip of the stylet <NUM> terminate at (but not extend from) the sidewall opening 110o, coring of tissue during insertion of the cannula <NUM> can be reduced or prevented.

Turing now to the embodiments shown schematically in <FIG>, <FIG>, and <FIG>, in some aspects, the present disclosure provides systems that include a cannula <NUM> in accordance with the disclosure and an electrode <NUM> this is insertable into the cannula <NUM>. In certain of these embodiments, the electrode <NUM> is provided with a rounded (e.g., hemispherical) distal tip 125d. In certain of these embodiments, the electrode <NUM> is straight with no bend. Materials for forming the electrode <NUM> include metals and metal alloys as stainless steel, Inconel, or nitinol.

In some embodiments the electrode <NUM> can be operated in unipolar fashion, for example, in conjunction with one or more return electrodes positioned on a patient's body. In some embodiments, the electrode <NUM> can be operated in a bipolar fashion, for example, with a distal tip <NUM> of the cannula <NUM> acting as the other member of the bipolar pair, in which case the electrode <NUM> and/or cannula <NUM> will be suitably insulated to avoid shorting the electrode <NUM> and cannula <NUM>.

When the distal tip 125d of an electrode <NUM> that has been inserted through a cannula tube <NUM> from a proximal end of a cannula <NUM> in accordance with the present disclosure (e.g., by being inserted through a hub <NUM> like that shown in <FIG> at a proximal end 110p of the cannula tube <NUM>) has traveled though the cannula tube <NUM> to a point where the distal tip 125d reaches the ramp <NUM> of the cannula tip <NUM>, the ramp <NUM> acts to deflect the electrode distal tip 125d out through the sidewall opening 110o of the cannula tube <NUM>, rather than allowing the electrode distal tip 125d of the electrode <NUM> to continue traveling into the cannula tip <NUM>. In these embodiments, the width of the electrode <NUM> is narrower than the width of the cannula tube <NUM> lumen <NUM> and is wider than the slot that is formed in the ramp <NUM> (or the channel or hole that is formed in the ramp <NUM> in other embodiments). In this regard, a top view of a cannula <NUM> in accordance with the present disclosure is illustrated <FIG>, in which can be seen the sidewall opening 110o of the cannula tube <NUM> and the ramp <NUM> of the inserted cannula tip <NUM>. A weld W securing the cannula tip <NUM> to the cannula tube <NUM> can be seen in the right-hand portion of the photograph. As seen from <FIG>, when an electrode <NUM> that has been inserted into a proximal end of the cannula <NUM> reaches the ramp <NUM>, the ramp acts to deflect the distal tip 125d of the electrode <NUM> out through the sidewall opening 110o of the cannula tube <NUM>.

In some embodiments, the system is further provided with a container of fluid for injection, for example, a container of anesthetic fluid, saline, contrast media (including radiopacity fluid), dye-containing fluid, or steroid-containing fluid. For example, injection fluid can be provided in a syringe that is engageable with the cannula hub <NUM>. As noted above, the cannula designs of the present disclosure are advantageous in that they allow fluid that is injected though the lumen of the cannula tube to be dispensed from a distal end of the cannula while at the same time preventing an inserted electrode to proceed beyond the side port to the distal end of the cannula.

Claim 1:
A cannula comprising (a) a cannula tube (<NUM>) comprising a proximal end, a distal end (110dt), a cannula tube lumen (<NUM>), a sidewall (<NUM>), and a sidewall opening (110o) extending through the sidewall, the sidewall opening having a proximal end and distal end and (b) a cannula tip (<NUM>) secured to the distal end of the cannula tube, the cannula tip comprising a proximal tip portion (120p) that is inserted into the cannula tube lumen and a distal tip portion (120d) that extends beyond the distal end of the cannula tube, the cannula tip being configured to allow fluid to flow therethrough, wherein the proximal tip portion of the cannula tip comprises a ramp (<NUM>) at a proximal end thereof, wherein the ramp is configured to eject a distal tip of an elongated device through the sidewall opening of the cannula tube as the elongated device is inserted through the cannula tube from the proximal end of the cannula tube.