Patent Description:
Microwave ablation antennae are a well-known mechanism for treating cancerous lesions and tumors in the body. For example, treatment of liver tumors is often undertaken by the placement of one or more microwave ablation antennae proximate the tumor and then treatment with microwave radiation up to and exceeding 150W of power for a duration sufficient to coagulate and kill the tissue of the tumor and some margin of healthy tissue.

Some microwave ablation antennae are cooled using compressed or liquefied CO<NUM> gas, which during expansion absorbs energy from the antenna and particularly the coaxial cabling to help limit damage to healthy tissue proximate the radiating section which is normally formed on a distal portion of the antenna. The actual radiator of such devices is often separated from the cooling gas flow.

In an alternative arrangement, a circulating fluid, generally saline or deionized water, is pumped through the microwave ablation antenna assembly. One such configuration has been described in detail in commonly assigned <CIT> <FIG> depicts a microwave ablation antenna assembly <NUM> configured for circulating a fluid therethrough. As shown in <FIG>, the microwave ablation assembly <NUM> includes a transition <NUM>, which connects via a coaxial cable to a microwave ablation generator (not shown). The transition <NUM> allows for a <NUM>° change in direction of the coaxial cable entering the transition <NUM> to the coaxial cable <NUM> of the microwave ablation assembly <NUM>. The coaxial cable <NUM> extends perpendicularly from the transition <NUM> and concludes at a radiating section <NUM>. The radiating section <NUM> may take many forms including monopole, dipole, symmetric and asymmetric configurations. The coaxial cable <NUM> extends through a first tubular member <NUM>, which is itself housed within a second tubular member <NUM>. Between the coaxial cable <NUM> and the first tubular <NUM> member is a first fluid channel <NUM> and between the first tubular <NUM> member and the second tubular member <NUM> is a second fluid channel <NUM>. The transition <NUM> is received within a first end of a hub <NUM>, a hub cap <NUM> is received at a second end of the hub <NUM>, and is itself designed to receive and secure the second tubular member <NUM>. O-rings <NUM> and <NUM> formed on the hub cap <NUM> and the transition <NUM>, form seals creating a watertight compartment <NUM> therebetween.

Further, as shown in <FIG>, the watertight compartment <NUM> is separated into inflow chamber <NUM> and outflow chamber <NUM> by hub divider <NUM>. The hub divider <NUM> receives the first tubular member <NUM> and maintains it in alignment with the second tubular member <NUM>. The hub divider <NUM> is formed of an elastomeric material and forms a seal around the first tubular member <NUM> which, in combination with a compression fit within the hub <NUM>, restricts the egress of fluid in inflow chamber <NUM> to the first fluid channel <NUM>, and prevents fluid returning through second fluid channel <NUM> and entering outflow chamber <NUM> from re-entering the inflow chamber <NUM>. Also shown in <FIG> are inflow port <NUM> and outflow port <NUM> which connect to inflow chamber <NUM> and outflow chamber <NUM>, respectively. A wire <NUM> is depicted extending through the hub <NUM> and inflow chamber <NUM> and entering the first tubular member <NUM> where it will terminate at a point proximate the radiating section <NUM> and include a thermocouple (not shown) to detect the temperature or the microwave ablation assembly <NUM>. The entire hub <NUM>, hub cap <NUM>, and transition <NUM>, once assembled, are placed within a handle assembly <NUM> for ease of gripping and other ergonomic concerns.

Though the microwave ablation antenna assembly <NUM> is quite successful commercially and is currently sold by Medtronic as part of the EMPRINT™ ablation system, improvements are always desirable.

<CIT> discloses a microwave ablation system including an antenna assembly configured to deliver microwave energy from an energy source to tissue and a coolant source operably coupled to the energy source and configured to selectively provide fluid to the antenna assembly via a fluid path. The system also includes a controller operably coupled to the energy source and a piezoelectric transducer operably coupled to the fluid path to detect a force of fluid flow through the fluid path. The piezoelectric transducer is configured to generate a signal based on the detected force of fluid through the fluid path. The controller is configured to control the energy source output based on the generated signal.

The present disclosure is directed to a microwave ablation antenna assembly. In accordance with one aspects of the disclosure the assembly includes a coaxial cable terminating in a radiating section, a first (inner) tubular member circumscribing the coaxial cable and spaced therefrom to permit fluid flow therebetween, and a second (outer) tubular member circumscribing the first tubular member and spaced therefrom to permit fluid flow therebetween. The assembly further includes a hub configured to receive the coaxial cable, first tubular member, and second tubular member, the hub including a fluid inflow chamber and a fluid outflow chamber, a hub divider separating fluid inflow chamber from the fluid outflow chamber, and an inflow tube insert adhered to the inflow tube member and interacting with the hub divider to form a seal prohibiting fluid flow between the inflow chamber and outflow chamber except via the spacing between the coaxial cable and the first tubular member and between the first tubular member and the second tubular member. A proximal portion of the integrated hub divider and hub cap is secured in the hub.

In accordance with a further aspect of the disclosure the microwave ablation antenna assembly includes a wall extending from the hub and interfacing with the hub divider to prevent movement of hub divider. Fluid flow is directed from a fluid inflow chamber into the space formed between the coaxial cable and the inner tubular member, and the fluid flow may extend to the radiating section. Further, the fluid flow may return from the radiating section in the spacing between the outer tubular member and the inner tubular member. The microwave ablation antenna assembly may further include a hub cap configured to receive the outer tubular member and be received in the hub to form the outflow chamber.

A further aspect of the present disclosure is directed to a microwave ablation antenna assembly including a coaxial cable terminating in a radiating section, a first tubular member circumscribing the coaxial cable and spaced therefrom to permit fluid flow therebetween, and a second tubular member circumscribing the first tubular member and spaced therefrom to permit fluid flow therebetween. The assembly includes a hub configured to receive the coaxial cable, first tubular member, and second tubular member, the hub including a fluid inflow chamber and a fluid outflow chamber. Still further the assembly includes an integrated hub divider and hub cap separating the fluid inflow chamber from the fluid outflow chamber and prohibiting fluid flow between the inflow chamber and outflow chamber except via the spacing between the coaxial cable and the first tubular member and between the first tubular member and the second tubular member.

In accordance with a further aspect of the present disclosure the microwave ablation antenna assembly includes at least one rib formed on an interior surface of the hub and engaging at least one groove formed on the integrated hub divider and hub cap. The assembly may further include at least one o-ring forming a seal in combination with the integrated hub divider and hub cap to prevent fluid flow between the fluid inflow chamber and the fluid outflow chamber. Fluid flow is directed from a fluid inflow chamber into the space formed between the coaxial cable and the inner tubular member. Fluid flow may extend to the radiating section and may return from the radiating section in the spacing between the outer tubular member and the inner tubular member.

The integrated hub divider and hub cap may include a window fluidly connecting the spacing between the outer tubular member and the inner tubular member with the outflow chamber. The proximal portion of the inner tubular member may be adhered to a proximal portion of the integrated hub divider and hub cap and a proximal portion of the outer tubular member may be adhered to a distal portion of the integrated hub divider and hub cap.

A further aspect of the present disclosure is directed top a microwave ablation antenna assembly including a coaxial cable terminating in a radiating section, a first tubular member circumscribing the coaxial cable and spaced therefrom to permit fluid flow therebetween, and a second tubular member circumscribing the first tubular member and spaced therefrom to permit fluid flow therebetween. The assembly further includes a hub configured to receive the coaxial cable, first tubular member, and second tubular member, the hub including a fluid inflow chamber and a fluid outflow chamber and an integrated transition cap and hub divider located substantially within the hub and separating the fluid inflow chamber from the fluid outflow chamber and prohibiting fluid flow between the inflow chamber and outflow chamber except via the spacing between the coaxial cable and the first tubular member and between the first tubular member and the second tubular member, wherein the transition cap is secured to the hub.

In accordance with a further aspect of the present disclosure the assembly includes at least one rib formed on an interior surface of the hub and engaging at least one groove formed on the integrated transition cap and hub divider. The assembly may further include at least one o-ring forming a seal in combination with the integrated transition cap and hub divider to prevent fluid flow between the fluid inflow chamber and the fluid outflow chamber, wherein fluid flow is directed from a fluid inflow chamber into the space formed between the coaxial cable and the inner tubular member.

In accordance with a further aspect of the disclosure, the fluid flow returns to the hub outflow chamber in the spacing between the outer tubular member and the inner tubular member. Further, integrated transition cap and hub divider may include a window fluidly connecting the spacing between the inner tubular member and the coaxial cable with the fluid inflow chamber. Still further, the proximal portion of the inner tubular member may be adhered to a hub divider portion of the integrated transition cap and hub divider.

Objects and features of the present disclosure will become apparent to those of ordinary skill in the art when descriptions of various embodiments thereof are read with reference to the accompanying drawings, of which:.

<FIG> depicts a first embodiment of the present disclosure. Handle assembly <NUM> is depicted enclosing a hub <NUM>. Note common numbering conventions are used where possible amongst all embodiments of the present disclosure. The hub <NUM> is mated on a first end to a transition <NUM>, which connects a coaxial cable extending to a microwave generator (not shown) to a second coaxial cable <NUM> at a <NUM>° angle. The transition <NUM> mates with the hub <NUM> using an o-ring <NUM>. Extending up through the opening in the handle assembly <NUM> for receiving the first coaxial cable is a wire <NUM> which extends into the hub <NUM> and terminates at a thermocouple (not shown) for sensing the temperature of the microwave ablation assembly <NUM>, and more particularly the temperature proximate the radiating section <NUM> (<FIG>).

As depicted in <FIG>, the hub <NUM> has a different internal configuration than that depicted in <FIG>. One difference is the formation of a wall <NUM> separating the inflow chamber <NUM> from the outflow chamber <NUM>. In accordance with this embodiment of the present disclosure, an inflow tube insert <NUM>, is received within a hub divider <NUM>. The inflow tube insert <NUM> includes a flange <NUM> formed on one end. The flange <NUM> forms a surface upon which fluid in the inflow chamber <NUM> acts, and when the inflow chamber <NUM> is pressurized, compresses the hub divider <NUM> forming a water tight seal. As a result of this seal between the flange <NUM> and the hub divider <NUM>, the circulated fluid is forced into the spacing between the first tubular member <NUM> and the coaxial cable <NUM>. After flowing to the distal portion of the microwave ablation assembly <NUM>, the fluid flows back in the spacing between the first tubular member <NUM> and the second tubular member <NUM>, to be released into the outflow chamber <NUM>, in much the same fashion as the device shown in <FIG>. The inflow tube insert <NUM> may be adhered or bonded (e.g., with a two part adhesive) to first tubular member <NUM>, effectively securing the first tubular member <NUM> within the handle assembly <NUM>. In addition to the pressure applied to the flange <NUM> to create a seal between the inflow tube insert <NUM> and the hub divider <NUM>, the opening in the hub divider <NUM> through which the inflow tube insert <NUM> is placed can be sized such that it has a smaller inner diameter than the outer diameter of the inflow tube insert <NUM>. In addition, the outer diameter of the hub divider <NUM> may be larger than the space <NUM> within the hub <NUM> which receives the hub divider <NUM>. The hub divider <NUM>, being made of an elastomeric material, compresses to be received within the space and compresses again to receive the inflow tube insert <NUM>. In this manner fluid is prevented from passing from the inflow chamber <NUM> to the outflow chamber <NUM> without first traversing the lengths of the first and second tubular members <NUM> and <NUM> respectively. Again a hub cap <NUM> secures the second tubular member <NUM> in the hub <NUM>, and may employ an o-ring <NUM> to prevent fluid flow out of the hub <NUM> other than out the outflow port <NUM>. Ribs <NUM> formed on the hub <NUM> help secure the hub cap <NUM> by mating with corresponding grooves <NUM> formed in the hub cap <NUM>.

<FIG> depicts a second embodiment of the present disclosure. The primary difference between the embodiment of <FIG> and the embodiment described above in <FIG> is again the internal configuration of the hub <NUM>. Unlike the embodiment of <FIG>, where wall <NUM> separated the inflow chamber <NUM> from the outflow chamber <NUM>, in <FIG> this separation is formed by an integrated hub divider and hub cap <NUM>. The integrated hub divider and hub cap <NUM> has a distal portion <NUM> which is substantially similar to the hub cap <NUM> shown in <FIG>. The distal portion <NUM> is adhered to the second tubular member <NUM> and forms a seal with the hub <NUM> in conjunction with ribs <NUM> and grooves <NUM> formed on the hub <NUM> and distal portion <NUM>. To ensure water tight integrity of the seal an o-ring <NUM> is employed in addition to the grooves <NUM> and ribs <NUM>. The proximal portion of the second tubular <NUM> member terminates in an intermediate portion <NUM> of the integrated hub divider and hub cap <NUM>. The intermediate portion <NUM> has one or more openings or windows <NUM> formed therein permitting the flow of fluid from the spacing between the outer tubular member <NUM> and the inner tubular member <NUM> and into the out flow port <NUM>.

The intermediate portion <NUM> of the integrated hub divider and hub cap <NUM> connects to a proximal portion <NUM>. The proximal portion <NUM> is secured in the hub <NUM> by mating ribs <NUM> formed on an interior surface of the hub <NUM> with a groove <NUM> formed in the proximal portion <NUM>. As shown in <FIG>, an o-ring <NUM> forms a seal between the proximal portion <NUM> and the hub <NUM> which effectively separates the inflow chamber <NUM> from the out flow chamber <NUM>. The proximal portion <NUM> is adhered to an outer surface of the first tubular member <NUM> and in conjunction with the remaining portions of the integrated hub divider and hub cap <NUM> secure the inner tubular member <NUM>.

<FIG> depicts a further embodiment of the present disclosure. Again one of the main differences is the shape of the hub <NUM>. As depicted, the hub <NUM> is shaped such that the hub cap <NUM> is completely eliminated. The outer tubular member <NUM> may be received in and adhered to a bore <NUM> formed in a portion of the hub <NUM>. On the opposite end of the handle assembly <NUM>, an integrated transition cap and hub divider <NUM> connects to the transition <NUM> and helps hold the coaxial cable <NUM> in the transition <NUM>. The integrated transition cap and hub divider <NUM> is formed of three integrated sections. The first is a transition cap <NUM>, which as noted above, secures the coaxial cable <NUM> in the transition <NUM>. The embodiments of <FIG> and <FIG> also incorporate transition caps that perform similar functionality but play no role in separating the inflow chamber <NUM> from the out flow chamber <NUM>, and thus are not described above. As shown the transition cap <NUM> is secured to the hub <NUM> by a rib <NUM> formed on the hub <NUM> which is received into a groove <NUM> formed on the transition cap <NUM>. An o-ring <NUM> prevents fluid from flowing from the fluid inflow chamber <NUM> out of the handle assembly <NUM>.

Extending from the transition cap <NUM> is an intermediate portion <NUM> of the integrated transition cap and hub divider <NUM>. The intermediate portion <NUM> includes one or more openings or windows <NUM> permitting fluid to enter the integrated transition cap and hub divider <NUM> and reach the spacing between the coaxial cable <NUM> and the inner tubular member <NUM>. The proximal portion of the inner tubular member <NUM> terminates proximate the window <NUM>. In one embodiment a parallel flange <NUM> forms a proximal portion of the hub divider portion <NUM> of the integrated transition cap and hub divider <NUM>. The inner tubular member <NUM> may be adhered to an inner surface of a bore <NUM> formed in the hub divider portion <NUM> of the integrated transition cap and hub divider <NUM>. The hub divider portion <NUM> is secured to the hub <NUM> by a rib <NUM> formed on an inner surface of the hub <NUM> and a groove <NUM> formed in the hub divider <NUM>. An o-ring <NUM> creates a seal between the inflow chamber <NUM> and the outflow chamber <NUM>.

In accordance with the present disclosure there are several instances described of hub dividers (e.g., <NUM>, <NUM>, and proximal portion <NUM>). Each of these is formed of an elastomeric material and may be adhered to an inner tubular member <NUM> or inflow tube insert <NUM> using one or more adhesives. The inner tubular member <NUM> and inflow tube insert may be formed of a variety of materials including fiberglass, carbon fiber, stainless steel, thermoplastics, other extruded and un-extruded materials, and the like. The adhesives may be selected for their bonding properties for the materials selected as well as their heat resistance as the coaxial cable <NUM> will become heated during usage. Similar materials and adhesives may be employed for the hub cap <NUM> and the outer tubular member <NUM>. Further, while the hub <NUM> is formed of a harder more durable medical grade plastic, in the embodiment of <FIG>, an adhesive may be chosen for the connecting of the hub <NUM> to the outer tubular member <NUM>. Similarly, the inflow tube insert <NUM> in the embodiment of <FIG> may be adhered to the wall <NUM> of the hub <NUM> by selection of appropriate adhesives.

Claim 1:
A microwave ablation antenna assembly (<NUM>) comprising:
a coaxial cable (<NUM>) terminating in a radiating section (<NUM>);
a first tubular member (<NUM>) circumscribing the coaxial cable and spaced therefrom to permit fluid flow therebetween;
a second tubular member (<NUM>) circumscribing the first tubular member and spaced therefrom to permit fluid flow therebetween;
a hub (<NUM>) configured to receive the coaxial cable, first tubular member, and second tubular member, the hub including a fluid inflow chamber (<NUM>) and a fluid outflow chamber (<NUM>);
further comprising an integrated hub divider and hub cap component (<NUM>) separating the fluid inflow chamber from the fluid outflow chamber to prohibit fluid flow between the inflow chamber and outflow chamber except via the spacing (<NUM>; <NUM>) between the coaxial cable and the first tubular member and between the first tubular member and the second tubular member, wherein a proximal portion (<NUM>) of the integrated hub divider and hub cap component (<NUM>) is secured in the hub, anc wherein a distal portion (<NUM>) of the integrated hub divider and hub cap component (<NUM>) forms a hub cap (<NUM>) received at the distal end of the hub.