Patent Description:
During thermal treatment of the prostate, energy is delivered from an energy-delivery device to eliminate or reduce the diseased cells in the prostate. An unwanted side effect of heating the diseased tissue can be over-heating adjacent non-diseased tissue and organs. For example, in the thermal therapy of the prostate, the rectum and other healthy tissues near the prostate can be heated beyond what is safe or healthy for the patient. It is desired to limit the thermal dose or maximum temperature applied to these tissues, such as the rectal wall proximal to the prostate.

Endorectal cooling devices (ECDs) can be used to maintain the temperature of the rectum and surrounding tissue at a safe level. These devices generally include an elongated body and an internal fluid circuit. An example of an ECD is disclosed in <CIT>.

When existing ECDs are inserted into the rectum, a volume of air is introduced into the rectal cavity to form gas bubbles (e.g., air bubbles). The gas bubbles rise in the rectal cavity and become disposed between the ECD and the rectal wall proximal to the prostate. In addition, gas bubbles from intestinal gases naturally exist in the rectal cavity and behave similarly to the gas bubbles formed during ECD insertion. For example, <FIG> illustrates gas bubbles <NUM> disposed between the cooling surface <NUM> of ECD <NUM> and the rectal wall <NUM> of rectum <NUM> proximal to prostate <NUM>. For purpose of this illustration and for clarity, the distance between the ECD's cooling surface <NUM> and the rectal wall <NUM> is illustrated as larger than it is in practice. In operation, the ECD's cooling surface <NUM> is disposed proximal or adjacent to the rectal wall <NUM>, and gas bubbles <NUM> becomes trapped therebetween. For completeness, <FIG> illustrates a thermal applicator <NUM> inserted transurethrally through the upper and lower portions of prostate <NUM>. These gas bubbles reduce the effectiveness of the ECD by impeding the heat transfer between the ECD and the rectal wall. Gas bubbles also create an acoustic impedance which can reflect ultrasound energy and affect tissue heating.

To remove the gas bubbles <NUM>, the ECD <NUM> can be swept side to side. <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT> describe prior art.

It would be desirable to reduce or eliminate the gas bubbles in the rectal cavity.

Example embodiments described herein have innovative features, no single one of which is indispensable or solely responsible for their desirable attributes. The following description and drawings set forth certain illustrative implementations of the disclosure in detail, which are indicative of several exemplary ways in which the various principles of the disclosure may be carried out. The illustrative examples, however, are not exhaustive of the many possible embodiments of the disclosure. Without limiting the scope of the claims, which define the invention, some of the advantageous features will now be summarized. Other objects, advantages and novel features of the disclosure will be set forth in the following detailed description of the disclosure when considered in conjunction with the drawings, which are intended to illustrate, not limit, the invention.

An aspect of the invention is directed to an endorectal cooling device (ECD) comprising: an elongated body having an insertable portion for insertion into a rectum of a patient and an external portion that remains external to the rectum, the insertable portion having an external cooling surface; a cooling fluid circuit in the elongated body that extends from the external portion to the insertable portion, the cooling fluid circuit circulating a cooling fluid to regulate a temperature of the cooling surface; and a gas bubble removal means disposed on or defined in the cooling surface.

In one or more embodiments, the gas bubble removal means comprises a tube or a coil disposed on the cooling surface. In one or more embodiments, the tube or the coil is fluidly coupled to a vacuum pump, and at least one hole is defined in the tube or the coil. In one or more embodiments, the at least one hole is aligned with a rectal wall proximal to a prostate. In one or more embodiments, the gas bubble removal means comprises the coil, and the coil is wrapped around an insertable portion of the ECD in a spiral.

In one or more embodiments, the gas bubble removal means comprises the tube, and the tube comprises a loop of tubing. In one or more embodiments, the loop of tubing is elongated along an axis that is parallel to a length of an insertable portion of the ECD. In one or more embodiments, the ECD further comprises a plurality of the loops disposed laterally from each other along the cooling surface.

In one or more embodiments, the gas bubble removal means comprises a mesh structure disposed in a gap in the cooling surface. In one or more embodiments, the mesh structure is fluidly coupled to a vacuum pump via a tube. In one or more embodiments, the gas bubble removal means comprises a plurality of holes defined in the cooling surface, and the holes are fluidly coupled to a low-pressure source via a gas bubble removal channel, the gas bubble removal channel defined in a housing of the ECD.

Another aspect of the invention is directed to an endorectal cooling device (ECD) comprising: an elongated body having an insertable portion for insertion into a rectum of a patient and an external portion that remains external to the rectum, the insertable portion having an external cooling surface; a gas bubble removal channel defined in the elongated body; a plurality of holes defined in the cooling surface, the holes extending from the cooling surface to the gas bubble removal channel; a low-pressure source fluidly coupled to the holes via the gas bubble removal channel; and a cooling fluid circuit defined in the elongated body, the cooling fluid circuit in thermal communication with the cooling surface.

In one or more embodiments, the low-pressure source comprises a Venturi structure that is formed in a proximal end of the elongated body. In one or more embodiments, the low-pressure source comprises a vacuum pump.

In one or more embodiments, the cooling fluid circuit comprises a cooling fluid channel that extends in a loop from a proximal end to a distal end of the elongated body. In one or more embodiments, a portion of the cooling fluid channel is disposed between the cooling surface and the gas bubble removal channel. In one or more embodiments, an internal wall defines each hole, the internal wall extending to the gas bubble removal channel such that the holes are only fluidly coupled to the gas bubble removal channel. In one or more embodiments, each internal wall forms a cone that defines each hole.

In one or more embodiments, the ECD further comprises an ultrasound coupling fluid channel defined in the elongated body, the ultrasound coupling fluid channel extending from the proximal end to the distal end of the elongated body. In one or more embodiments, an outlet of the ultrasound coupling fluid channel is disposed adjacent a distal end of the cooling surface. In one or more embodiments, an ingress portion of the cooling fluid channel is between the ultrasound coupling fluid circuit and the gas bubble removal channel. In one or more embodiments, the gas bubble removal channel is between the ingress portion of the cooling fluid and an egress portion of the cooling fluid.

For a fuller understanding of the nature and advantages of the present concepts, reference is made to the following detailed description of preferred embodiments in connection with the accompanying drawings.

A gas bubble removal device is disposed on or defined in the ECD's external cooling surface, which is disposed proximal to the prostate when the ECD is inserted into a patient's rectum. The gas bubble removal device includes one or more features for removing gas bubbles after the ECD is inserted into the patient's rectum.

In some embodiments, the gas bubble removal device includes a coil or a tube (in general, coil) that is disposed on the ECD's external cooling surface. The gas bubble removal coil causes a gap to form between the ECD's cooling surface and the rectal wall proximal to the prostate. In addition, the gas bubble removal coil can provide an irregular path for the gas bubbles to travel, which is energetically more favorable than the smooth ECD external surface. In some embodiments, the gas bubble removal coil can be fluidly coupled to a vacuum pump to remove the gas bubbles. For example, the gas bubble removal coil can include one or more holes that is/are aligned with the rectal wall proximal to the prostate. A vacuum can be applied to the gas bubble removal coil which causes fluid, including the gas bubbles, to enter the hole(s) and flow through the coil to an external fluid reservoir.

In another embodiment, the gas bubble removal device includes a mesh structure disposed on the ECD's external cooling surface. For example, the mesh structure can form a portion of the ECD's external cooling surface. Alternatively, the mesh structure can form a portion of the ECD's housing. The mesh structure is fluidly coupled to a vacuum pump (e.g., via one or more tubes) to remove the gas bubbles. A vacuum can be applied to the mesh structure which causes fluid, including the gas bubbles, to flow through the mesh structure to an external fluid reservoir (e.g., via one or more tubes).

In another embodiment, the gas bubble removal device includes a plurality of holes defined in the ECD's external cooling surface and/or housing. The holes are fluidly coupled to a first end of a gas bubble removal channel. A low-pressure source, such as a vacuum pump or a Venturi structure, is fluidly coupled to a second end of the gas bubble removal channel. The low-pressure source causes fluid and gas bubbles to flow through the holes and the gas bubble removal channel for collection in an external reservoir.

In some embodiments, the gas bubble removal device includes a combination of two or more of the features described above. For example, the gas bubble removal device can include a combination of any of the coil, tube, mesh, and/or holes.

In some embodiments, ultrasound-visible markers can be disposed on the ECD that allow the ECD to be visible with ultrasound imaging. In addition, the ECD can include an ultrasound coupling fluid channel that introduces ultrasound coupling fluid between the ECD and the rectal wall. Additionally or alternatively, the ECD can include a cooling fluid circuit that circulates cooling fluid in the ECD to cool and/or regulate the temperature of the cooling surface to thereby cool and/or regulate the temperature of the rectal wall and surrounding anatomy.

<FIG> illustrates an elongated ECD <NUM> having a gas bubble removal coil <NUM> according to one or more embodiments. The gas bubble removal coil <NUM> is wrapped around an insertable portion <NUM> of ECD <NUM> in a spiral manner. For example, the gas bubble removal coil <NUM> has a central axis that is generally parallel to an axis <NUM> that defines the length of the insertable portion <NUM>. When the insertable portion <NUM> is inserted into the rectum <NUM>, the gas bubble removal coil <NUM> is disposed between the rectal wall <NUM> and the ECD's cooling surface <NUM> (e.g., on the housing of ECD <NUM>) in a gap <NUM> therebetween. The gas bubble removal coil <NUM> can provide a surface along which the gas bubbles <NUM> can travel to escape that is energetically preferable to the smooth cooling surface <NUM> of the ECD <NUM>. The gas bubble removal coil <NUM> can comprise a single tube or multiple tubes. For example, multiple tubes can be disposed next to each other and run in parallel to form the gas bubble removal coil <NUM>. Alternatively, multiple tubes can be connected (e.g., serially) end-to-end to form the gas bubble removal coil <NUM>.

The coil <NUM> includes one or more optional holes <NUM> that is/are in fluid communication with a vacuum pump <NUM> or other low-pressure source to extract the gas bubbles <NUM>. In the embodiment where the gas bubble removal coil <NUM> includes multiple tubes disposed next to each other, one, some or all of the tubes can include a hole <NUM>, and such tube(s) can be in fluid communication with the vacuum pump <NUM>. The holes <NUM> can be distributed along the length of the coil <NUM> or they can be disposed only in certain portions of the coil <NUM>. The vacuum pump <NUM> can be powered electrically or manually. In some embodiments, the vacuum pump <NUM> is disposed on or in the housing of the ECD <NUM>. A vacuum tube <NUM> fluidly couples the vacuum pump <NUM> to the coil(s) <NUM>. The vacuum tube <NUM> can be disposed on the exterior surface of the ECD <NUM> and/or in a chamber or channel that extends through the ECD <NUM>.

A cooling fluid circuit <NUM> circulates cooling fluid through the ECD <NUM>. The cooling fluid circuit <NUM> includes a cooling fluid reservoir <NUM> and a pump <NUM> for circulating the cooling fluid through the cooling fluid circuit <NUM>. The cooling fluid circuit <NUM> can extend from a proximal end <NUM> to a distal end <NUM> of the ECD <NUM> including through the insertable portion <NUM>. The cooling fluid circuit <NUM> can pass proximally to the cooling surface <NUM> so that the cooling fluid is in thermal communication with the cooling surface <NUM> to reduce and/or regulate the temperature thereof, and thus to reduce and/or regulate the temperature of the rectal wall <NUM> and nearby patient anatomy.

The ECD <NUM> also includes optional ultrasound-visible markers <NUM>. The ultrasound-visible markers <NUM> have a higher acoustic impedance than the housing of the ECD <NUM>, which allows them to be visible using ultrasound. For example, the ultrasound-visible markers <NUM> can comprise titanium or another high-acoustic-impedance material.

<FIG> illustrates an example of an elongated ECD <NUM> having a gas bubble removal tube <NUM> according to an alternative embodiment. The tube <NUM> is disposed partially or fully on the external surface of an insertable portion <NUM> of the ECD <NUM>. The tube <NUM> comprises an elongated loop of tubing that extends along at least a portion of the length of the ECD <NUM>. For example, the tube <NUM> can form a rectangular or oval shape that is elongated along an axis <NUM> that is parallel to axis <NUM>. In some embodiments, the tube <NUM> can include two or more loops. For example, a first loop can be disposed inside a second loop (i.e., the first loop is wider, such as along an axis that is orthogonal to axis <NUM>, than the second loop such that the first loop fits within the second loop).

Alternatively, the first and second loops can be disposed adjacent or laterally from each other along the cooling surface <NUM> of the ECD <NUM>. In another embodiment, a plurality of loops can be disposed along the elongated length of the ECD <NUM> (e.g., along the cooling surface <NUM>), for example in an end-to-end configuration or in an overlapping configuration.

When the ECD <NUM> is inserted into the rectum <NUM>, at least some of the tube <NUM> is disposed between the rectal wall <NUM> and the ECD's cooling surface <NUM> (e.g., on the housing of ECD <NUM>) in a gap <NUM> therebetween. The tube <NUM> can provide a surface along which the gas bubbles <NUM> can travel to escape that is energetically preferable to the smooth cooling surface <NUM> of the ECD <NUM>.

One or more of the loops in tube <NUM> can include one or more holes <NUM> that is/are in fluid communication with a vacuum pump <NUM> to extract the gas bubbles <NUM>, for example as described above with respect to coil <NUM>. The ECD <NUM> can include ultrasound-visible markers such as ultrasound-visible markers <NUM>. In addition or in the alternative, the ECD <NUM> can include a cooling fluid circuit such as cooling fluid circuit <NUM>, which is not illustrated in <FIG> for clarity purposes only.

<FIG> illustrates an example of an elongated ECD <NUM> having a mesh or porous material <NUM> for removing gas bubbles according to an alternative embodiment. The mesh or porous material <NUM> is disposed in a gap <NUM> of the cooling surface <NUM> in the insertable portion <NUM> of the ECD <NUM> such that the mesh or porous material <NUM> faces the rectal wall <NUM> when the ECD <NUM> is inserted into the rectum <NUM>. The mesh or porous material <NUM> provides a surface along which the gas bubbles <NUM> can travel to escape that is energetically preferable to the smooth cooling surface <NUM> of the ECD <NUM>. In addition, the gas bubbles <NUM> can flow through the mesh or porous material <NUM> and into an internal or external channel <NUM> when a vacuum is applied by vacuum pump <NUM>. In some embodiments, the channel <NUM> is an internal channel that can be fluidly coupled (e.g., via a manifold) to other channels in the ECD <NUM>, such as for circulating cooling fluid. In some embodiments, the mesh or porous material <NUM> comprises a woven plastic sheet or a woven fabric.

The ECD <NUM> can include ultrasound-visible markers such as ultrasound-visible markers <NUM>. In addition or in the alternative, the ECD <NUM> can include a cooling fluid circuit such as cooling fluid circuit <NUM>, which is not illustrated in <FIG> for clarity purposes only.

<FIG> illustrates an example of an elongated ECD <NUM> having a plurality of holes <NUM> for removing gas bubbles according to an alternative embodiment. The holes <NUM> are defined in the housing <NUM> on the insertable portion <NUM> of the ECD <NUM> such as in cooling surface <NUM> and/or other portions of the elongated body. The holes <NUM> can be disposed in a regular or irregular arrangement. For example, the holes <NUM> can be disposed in an array, a pattern, or another regular arrangement. Alternatively, the holes <NUM> can be disposed irregularly in the housing <NUM>. Regardless of the arrangement, the holes <NUM> can have the same sizes and/or different sizes. For example, the holes can have (a) the same and/or different widths (e.g., diameters) and/or (b) the same and/or different cross-sectional profiles. In some embodiments, the holes <NUM> can be formed by 3D printing.

The holes <NUM> are fluidly coupled to a low-pressure source such that fluid in the rectum <NUM>, and any bubbles <NUM> in the fluid, is drawn through the holes <NUM> to one or more channels that extend(s) between the holes <NUM> and the low-pressure source.

<FIG> is a cross-section of ECD <NUM> through plane <NUM>-<NUM> in <FIG>. As illustrated in <FIG>, ECD <NUM> includes a plurality of channels defined in the housing <NUM>. For example, an ultrasound coupling fluid channel <NUM> is a first channel defined in the housing <NUM> and extends from a proximal end <NUM> to a distal end <NUM> of the ECD <NUM>. The proximal end <NUM> of the ultrasound coupling fluid channel <NUM> is fluidly coupled to an ultrasound coupling fluid reservoir <NUM> which can include a pump that causes the ultrasound coupling fluid to flow through the ultrasound coupling fluid channel <NUM> from the proximal end <NUM> to the distal end <NUM> of the ECD <NUM>. Additionally or alternatively, the ultrasound coupling fluid reservoir <NUM> can be disposed higher than the ECD <NUM> to gravity feed the ultrasound coupling fluid into the ultrasound coupling fluid channel <NUM>. The ultrasound coupling fluid can comprise a biocompatible liquid such as saline solution that has approximately the same acoustical impedance as the bodily fluids in the rectum <NUM>, for example to minimize acoustic reflection or scatter.

At or near the distal end <NUM>, the ultrasound coupling fluid channel <NUM> has a U-shaped bend <NUM> so that an outlet <NUM> of the ultrasound coupling fluid channel <NUM> is adjacent to a distal end <NUM> of the cooling surface <NUM>. The outlet <NUM> is preferably configured so that the ultrasound coupling fluid generally flows parallel to or towards the cooling surface <NUM> so that at least some ultrasound coupling fluid contacts the cooling surface <NUM> and/or other surfaces of the ECD <NUM> to improve ultrasound imaging and thermal coupling of tissue to the ECD <NUM>. In other embodiments, the ultrasound coupling fluid channel <NUM> can be configured so that the ultrasound coupling fluid is directed away from the cooling surface <NUM>. For example, the outlet <NUM> can be configured so that the ultrasound coupling fluid is directed towards the rectal wall <NUM> and away from the cooling surface <NUM>. In some embodiments, the flow or "current" of the ultrasound coupling fluid can move the bubbles towards the holes <NUM> or away from the cooling surface <NUM>, which can be an advantage of the ECD <NUM> configuration. In other embodiments, the ultrasound coupling fluid channel <NUM> can include a first exit that directs the ultrasound coupling fluid parallel to the cooling surface <NUM> and a second exit that directs the ultrasound coupling fluid away from the cooling surface <NUM>. The ultrasound coupling fluid provides an acoustic coupling medium to transfer ultrasound energy to and/or from the ECD <NUM>, such as during ultrasound imaging to position the cooling surface <NUM> of the ECD <NUM> with respect to the rectal wall <NUM>.

A cooling fluid channel <NUM> is a second channel defined in the housing <NUM> and extends from the proximal end <NUM> to the distal end <NUM> of the ECD <NUM> in a loop. At the proximal end <NUM>, the cooling fluid channel <NUM> is fluidly coupled to a cooling fluid reservoir <NUM> which can include a pump that causes the cooling fluid to flow through the cooling fluid channel <NUM> from the proximal end <NUM> to the distal end <NUM> of the ECD <NUM>. Additionally or alternatively, the cooling fluid reservoir <NUM> can be disposed higher than the ECD <NUM> to gravity feed the cooling fluid into the cooling fluid channel <NUM>. The cooling fluid can comprise a biocompatible liquid such as saline solution that can transfer thermal energy to and/or from the cooling surface <NUM>.

At or near the distal end <NUM>, the cooling fluid channel <NUM> has a U-shaped bend <NUM> that redirects the cooling fluid back towards the proximal end <NUM> of the ECD <NUM>. After the U-shaped bend <NUM>, the cooling fluid channel <NUM> is disposed adjacent to the cooling surface <NUM> such that thermal energy can be transferred between the cooling surface <NUM> and the cooling fluid. At the proximal end <NUM>, the cooling fluid channel <NUM> includes an optional Venturi structure <NUM> that causes a reduction in pressure, which can function as a vacuum pump to suck the ultrasound coupling fluid, entrained gas bubbles, and/or gas bubbles out of the interface between the rectal wall and the ECD and into the cooling fluid channel <NUM>. The cooling fluid exiting the cooling fluid channel <NUM> can flow into the cooling fluid reservoir <NUM> for recirculation back through the cooling fluid channel <NUM>. In some embodiments, the ultrasound coupling fluid and vacuum generating device are coupled to separate fluid circuits. In some embodiments, a heat exchanger can be disposed between the Venturi structure <NUM> and the cooling fluid reservoir <NUM> to reduce the temperature of the cooling fluid. In alternative embodiments, the Venturi structure <NUM> can be replaced with a vacuum pump, which can be disposed internally or externally with respect to the ECD <NUM>.

In some embodiments, when the ultrasound coupling fluid and the cooling fluid comprise the same or compatible types of fluid (e.g., saline), the ultrasound coupling fluid channel <NUM> and the cooling fluid channel <NUM> can be combined at the proximal end <NUM> of the ECD <NUM> such that the ultrasound coupling fluid channel <NUM> and the cooling fluid channel <NUM> having a single inlet. The single inlet can be fluidly coupled to a single fluid reservoir, which can be the same as the ultrasound coupling fluid reservoir <NUM> or the cooling fluid reservoir <NUM>. An internal wall that separates the ultrasound coupling fluid channel <NUM> and the cooling fluid channel <NUM> can be disposed between the proximal end <NUM> and the distal end <NUM> of the ECD <NUM>. Alternatively, the internal wall can be disposed at or after the U-shaped bend.

A gas bubble removal channel <NUM> is a third channel defined in the housing <NUM> and extends from the proximal end <NUM> to the distal end <NUM> of the ECD <NUM>. The gas bubble removal channel <NUM> is disposed between the ingress <NUM> and egress <NUM> portions of the cooling fluid channel <NUM>. The gas bubble removal channel <NUM> is in fluid communication with the fluids and gas bubbles <NUM>, disposed between the cooling surface <NUM> and the rectal wall <NUM>, via the holes <NUM> which extend from the cooling surface <NUM> to the gas bubble removal channel <NUM>. Near the proximal end <NUM>, the gas bubble removal channel <NUM> merges with the cooling fluid channel <NUM>. The low-pressure caused by the Venturi structure <NUM> causes fluids and gas bubbles <NUM> to flow through the holes <NUM> and out through the gas bubble removal channel <NUM>.

<FIG> is a detailed view of the cross-section illustrated in <FIG> at the distal end <NUM> of the ECD <NUM>. Representative arrows indicate the direction of fluid flow in the ultrasound coupling fluid channel <NUM>, the cooling fluid channel <NUM>, and the gas bubble removal channel <NUM>. In addition, <FIG> illustrates that the holes <NUM> are defined by an internal wall <NUM> that forms optional cones <NUM> having a tube <NUM> that extends from a cone opening <NUM> to the gas bubble removal channel <NUM> through the egress <NUM> portion of the cooling fluid channel <NUM>. The internal wall <NUM> fluidly couples the holes <NUM> to the gas bubble removal channel <NUM> but not to the cooling fluid channel <NUM>. In other embodiments, some or all of the holes <NUM> can be formed by a tube, such as tube <NUM>, without the cone opening <NUM>. In addition or in the alternative, the cone opening <NUM> can have a rectangular or square cross section instead of a circular cross section. In addition or in the alternative, the tube <NUM> can have a rectangular or square cross section instead of a circular cross section.

<FIG> is a detailed view of the cross-section illustrated in <FIG> at the proximal end <NUM> of the ECD <NUM>. Representative arrows indicate the direction of fluid flow in the ultrasound coupling fluid channel <NUM>, the cooling fluid channel <NUM>, and the gas bubble removal channel <NUM>. In addition, <FIG> illustrates that the Venturi structure <NUM> includes an inlet cone <NUM> having a tapered cross-sectional width for fluid flow, a generally cylindrical throat or neck <NUM> having a narrowed cross-section width for fluid flow, and an outlet cone <NUM> having an expanding cross-sectional width for fluid flow.

In some embodiments, the ECD <NUM>, <NUM>, and/or <NUM> can include an internal channel that introduces ultrasound coupling fluid between the respective ECD and the rectal wall <NUM>, such as ultrasound coupling fluid channel <NUM>.

The invention should not be considered limited to the particular embodiments described above, but rather is defined by the independent claim.

Claim 1:
An endorectal cooling device (ECD) (<NUM>) comprising:
an elongated body having an insertable portion (<NUM>) for insertion into a rectum of a patient and an external portion that remains external to the rectum, the insertable portion (<NUM>) having an external cooling surface (<NUM>);
a gas bubble removal channel (<NUM>) defined in the elongated body;
a plurality of holes (<NUM>) defined in the cooling surface, the holes extending from the cooling surface (<NUM>) to the gas bubble removal channel;
a low-pressure source fluidly coupled to the plurality of holes (<NUM>) via the gas bubble removal channel; and
a cooling fluid circuit (<NUM>) defined in the elongated body, the cooling fluid circuit (<NUM>) in thermal communication with the cooling surface (<NUM>),
wherein the cooling fluid circuit comprises a cooling fluid channel (<NUM>) that extends in a loop from a proximal end (<NUM>) to a distal end (<NUM>) of the elongated body, and wherein a portion of the cooling fluid channel (<NUM>) is disposed between the cooling surface (<NUM>) and the gas bubble removal channel (<NUM>).