Radiofrequency ablation device

Abstract

A device is described herein comprising a plurality of radio frequency ablation (RFA) elements, wherein the plurality of RFA elements are longitudinally disposed at a distal end of the device and a proximal end of the device coupled to a radiofrequency (RF) generator, wherein an intermediate section of the device independently couples each element of the plurality of RFA elements to the RF generator, wherein the plurality of RFA elements are configured to generate respective elliptical ablation zones when powered by the RF generator.

Description

[0001] UNITED STATES PATENT APPLICATION FOR:

[0002] RADIOFREQUENCY ABLATION DEVICE

[0003] Inventors: Matthew G. Cable

[0004] RELATED APPLICATIONS

[0005] This application claims the benefit of United States Application No. 63 / 638,848, filed April 25, 2024.

[0006] TECHNICAL FIELD

[0007] The disclosure herein relates to radiofrequency ablation devices.

[0008] INCORPORATION BY REFERENCE

[0009] Each patent, patent application, and / or publication mentioned in this specification is herein incorporated by reference in its entirety to the same extent as if each individual patent, patent application, and / or publication was specifically and individually indicated to be incorporated by reference.

[0010] BACKGROUND

[0011] Existing radiofrequency probes were originally designed for use in the spine, lung, and liver. They have been adapted for use in the appendicular skeleton but were intended to ablate spherical shaped tumors or cancer metastasis 25mm diameter or smaller. A long bone is a contained tubular region that cannot easily be ablated with existing probes. The length of the wire connecting current probes is not long enough to extend down the intramedullary canal of long bones, requiring surgeons to drill into the bone sideways to accommodate existing probes. Ablations also must be done individually over the length of involved bone. For this reason, bones with extensive metastasis are frequently managed with radiation rather than radiofrequency ablation. Radiation requires many individual treatments over several days and is associated with other morbidities such as swelling, pain, scarring, and skin changes. SUMMARY OF THE INVENTION

[0012] A device is described herein comprising under an embodiment a plurality of radio frequency ablation (RFA) elements, wherein the plurality of RFA elements are longitudinally disposed at a distal end of the device and a proximal end of the device coupled to a radiofrequency (RF) generator, wherein an intermediate section of the device independently couples each RFA element of the plurality of RFA elements to the RF generator, wherein the plurality of RFA elements are configured to generate respective elliptical ablation zones when powered by the RF generator.

[0013] In embodiments, longitudinally disposed RFA elements are uniformly spaced apart by a common interval.

[0014] In embodiments, the plurality of RFA elements comprise a length of 20 millimeters.

[0015] In embodiments, a powered RFA element of the plurality of RFA elements generates an elliptical ablation zone that longitudinally and proximally extends 4 millimeters.

[0016] In embodiments, the powered RFA element generates an elliptical ablation zone that longitudinally and distally extends 5 millimeters.

[0017] In embodiments, the common interval of 8 millimeters between adjacently powered RFA elements of the plurality of RFA elements provides an overlapping ablation zone.

[0018] In embodiments, the plurality of RFA elements comprise a length of 15 millimeters.

[0019] In embodiments, a powered RFA element of the plurality of RFA elements generates an elliptical ablation zone that longitudinally and proximally extends 3 millimeters.

[0020] In embodiments, the powered RFA element generates an elliptical ablation zone that longitudinally and distally extends 4.3 millimeters.

[0021] In embodiments, the common interval of 6 millimeters between adjacently powered RFA elements of the plurality of RFA elements provides an overlapping ablation zone.

[0022] In embodiments, the plurality of RFA elements comprise a length of 10 millimeters.

[0023] In embodiments, a powered RFA element of the plurality of RFA elements generates an elliptical ablation zone that longitudinally and proximally extends 1.3 millimeters.

[0024] In embodiments, the powered RFA element generates an elliptical ablation zone that longitudinally and distally extends 4.3 millimeters.

[0025] In embodiments, the common interval of 5 millimeters between adjacently powered RFA elements of the plurality of RFA elements provides an overlapping ablation zone. In embodiments, the plurality of RFA elements comprise a length of 7 millimeters.

[0026] In embodiments, a powered RFA element of the plurality of RFA elements generates an elliptical ablation zone that longitudinally and proximally extends 1.5 millimeters.

[0027] In embodiments, the powered RFA element generates an elliptical ablation zone that longitudinally and distally extends 2.9 millimeters.

[0028] In embodiments, the common interval of four millimeters between adjacently powered RFA elements of the plurality of RFA elements provides an overlapping ablation zone.

[0029] In embodiments, each RFA element of the plurality of elements is selectively powered by the RF generator.

[0030] In embodiments, the intermediate section comprises 30 cm.

[0031] In embodiments, the intermediate section provides couples the plurality of RFA elements to a water supply.

[0032] A method of ablating lesions in a column of bone using the device is described herein under an embodiment, the method comprising placing the plurality of RFA elements within and along an intramedullary space of a long bone and powering the plurality of RFA elements using the RF generator, wherein the powered plurality of RFA elements are configured to generated a continuous tubular ablation zone along the intramedullary space.

[0033] In embodiments, the bone includes a humerus, a tibia, and a femur.

[0034] BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1A is a side view of a probe with radio frequency ablation elements equally spaced at its distal end, under an embodiment.

[0036] Figure IB shows equally spaced radio frequency ablation elements at a distal end of a probe, under an embodiment.

[0037] Figure 1C shows equally spaced radio frequency ablation elements at a distal end of a probe, under an embodiment.

[0038] Figure ID shows equally spaced radio frequency ablation elements at a distal end of a probe, under an embodiment.

[0039] Figure 2A illustrates an ablation zone with all four radio frequency ablation elements utilized, under an embodiment. Figure 2B illustrates a bifurcated ablation zone with only three of four radio frequency ablation elements utilized, under an embodiment.

[0040] Figure 3 illustrates an ellipsoid ablation zone, under an embodiment.

[0041] DETAILED DESCRIPTION

[0042] Adaptation of existing radiofrequency ablation probe technology is described herein for use on tumors that involve more than one region in a long bone (i.e., femur, humerus, or tibia) or pelvis. Current probes are confined to 2cm or smaller ablation zones. When cancer spreads to bone, it often does so at multiple sites and can involve the entire shaft of a long bone or column of bone in the pelvis. Current treatment for bones diffusely involved by cancer is radiation or chemotherapy. A series of longitudinally stacked probes more easily treats an entire shaft or column of bone. Each probe in the series is powered independently to allow for customization of the bony region treated (i.e. skip lesions or avoiding treatment of an uninvolved segment of bone).

[0043] The device described herein incorporates existing singular, independently controllable, internally cooled, radiofrequency probes, in a new serial configuration that allows longer and large ablation zones. This is more ideally suited for metastatic bone disease outside of the spine, where involved segments of bone are not isolated and spherically shaped. Metastatic bone disease in the appendicular skeleton and pelvis involves multiple lesions arranged over longitudinal columns of bone. Current probes are designed primarily for spherically isolated lesions in the spine. To accommodate extraspinal bone lesions, currently available single probes need to be placed individually along the length of the bone via separate holes made into the bone, and the length of the probe can be insufficient to allow optimal access to the lesions. This product will offer an alternative to radiation, or an additional treatment if previous radiation has failed.

[0044] This novel device uses four existing radiofrequency probe elements, similar to Medtronic’s OsteoCool probe design, but arranged longitudinally on a single device. The spacing between the probes allows for overlapping ablation zones, so that if all probes are used, a single tubular shaped ablation zone will be formed without any gaps. Each probe can be controlled individually, if desired, allowing for tailoring the ablation zones required in cases where uninvolved segments of bone exist between metastatic lesions. The serial arrangement of four probes over a longer length allows for ablation of metastatic tumor along long bones (femur, humerus), with access longitudinally down the central “canal” of a long bone rather than drilling sideways into the bone shaft, which will prevent weakening of the bone and tumor contamination into surrounding tissues. This can also be applied to pelvic tumors involving anatomic “columns” of bone. The device can be used in conjunction with orthopedic management of pathologic or impending fractures to prevent tumor spread.

[0045] Individual probe sizes are currently 7mm, 10mm, 15mm, and 20mm in size, and each have a reproducible ellipsoid ablation zone and can each be monitored for temperature, power consumption, and tissue impedance. The proposed device will use four identical probes (i.e. four 7mm probes, or four 20mm probes). The maximum power applied to each probe is 20 watts, making the device compatible with existing radiofrequency generators capable of supporting 4 probes at up to 20 watts each.

[0046] Figure 1A provides an image of the probe device, under an embodiment. A proximal end of the probe device is coupled to a power source (or Radio Frequency (RF) generator) and also receives water inflow and outflow tubing. A distal end of the probe device features four overlapping radio frequency ablation (RFA) elements. An intermediary section of the probe device comprises a section of overlapping intermediary sections leading to longitudinally disposed RFA elements. (The intermediate section couples the RFA elements to the RF generator and also provides water flow to the RFA elements for cooling purposes). Under an embodiment, the intermediate section and distal RFA elements comprise a continuous and integrally formed shaft. The intermediate section comprises a length between 30 and 50 mm, but embodiments are not so limited. These lengths allow the distally oriented probe tip configuration to extend fully down a long bone intramedullary canal (humerus of femur). Under an embodiment, the four RFA elements are each 20 mm in length and are spaced apart at 8 mm intervals.

[0047] The spacing between RFA elements is determined by existing measured ablation zones from current probes. As an example, a 20 mm element generates a 29x21 mm ellipsoid ablation zone. These zones respectively extend 4 mm behind and 5 mm ahead of each element. Accordingly, an 8 mm spacing between elements generates overlapping ablation zones.

[0048] Under an embodiment, the four RFA elements are each 15 mm in length and are spaced apart at 6 mm intervals. A 15 mm element generates a 23 xl8 mm ellipsoid ablation zone. These zones respectively extend 3 mm behind (see Figure 3, 304) and 4.3 mm ahead (see Figure 3, 302) of each element. Accordingly, a 6 mm spacing between elements generates overlapping ablation zones. (See Figure IB).

[0049] Under an embodiment, the four RFA elements are each 10 mm in length and are spaced apart at 5 mm intervals. A 10 mm element generates a 17 xl3 mm ellipsoid ablation zone. These zones respectively extend 1.3 mm behind and 4.3 mm ahead of each element. Accordingly, a 5 mm spacing between elements generates overlapping ablation zones. (See Figure 1C).

[0050] Under an embodiment, the four RFA elements are each 7 mm in length and are spaced apart at 4 mm intervals. A 7 mm element generates a l l xlO mm ellipsoid ablation zone. These zones respectively extend 1.5 mm behind and 2.9 mm ahead of each element. Accordingly, a 4 mm spacing between elements generates overlapping ablation zones. (See Figure ID).

[0051] Note that the length of probe elements and the spacing therebetween may vary according to application.

[0052] Figure 2A illustrates a proposed ablation zone with all 4 elements utilized. The overlapping probe tip configuration extends along an intramedullary canal of a long bone. Each element of the configuration is independently activated and controlled to suit the patient’s anatomy. Figure 2A demonstrates that four activated elements generate a longitudinally continuous ablation zone. Figure 2B shows a bifurcated ablation zone resulting from activating elements one, three, and four, while maintaining element two in an inactive state.

[0053] Individual probe sizes are currently 7mm, 10mm, 15mm, and 20mm in size, and each have a reproducible ellipsoid ablation zone and can each be monitored for temperature, power consumption, and tissue impedance. As indicated above, the device uses four identical probes (i.e. four 7mm probes, or four 20mm probes). The maximum power applied to each probe is 20 watts, making the device compatible with existing radiofrequency generators capable of supporting 4 probes at up to 20 watts each.

[0054] Tissue impedance is variable depending on the patient. It is measured in real time by the probe element, along with power and temperature. The generator used varies power consumption depending on tissue resistance (impedance) and temperature to allow a slow and controlled temperature increase so that the tissue is not charred. The temperature reached is up to the clinician, and can range from 55 degrees C up to 85 degrees C. The only thing the generator can vary is the power, which has a maximum of 20 watts to each probe. The main application of the device is ablation of lesions in intramedullary spaces of long bones (humerus, tibia, femur, etc.). Secondary uses include the sacrum and pelvis, where long columns of bone exist but selective control of the probes is needed if the spanned length abuts a critical neurovascular structure, so one of the probe elements may need to be turned "off1. Under an embodiment, the device may be used for prophylactic and palliative management of painful bony cancer metastasis in the long bones and pelvis. The device may also be used in conjunction with impending and realized fractures of long bones and periacetabular cancer metastasis.

[0055] A device is described herein comprising a plurality of radiofrequency (RF) ablation probes coupled to a radiofrequency (RF) generator, where each probe of the plurality of RF ablation probes comprises a radiofrequency (RF) probe tip element, wherein each activated RF probe tip element generates an ablation zone, the plurality of RF ablation probes longitudinally disposed along a long bone intramedullary canal such that the respective longitudinally disposed RF ablation probe tips are equally spaced from each other, and the RF generator activating the plurality of RF ablation probe tip elements, wherein the activated RF ablation probe tip elements generate a continuous ablation zone.

Claims

CLAIMSWhat is claimed is:

1. A device comprising, a plurality of radio frequency ablation (RFA) elements, wherein the plurality of RFA elements are longitudinally disposed at a distal end of the device; a proximal end of the device coupled to a radiofrequency (RF) generator, wherein an intermediate section of the device independently couples each RFA element of the plurality of RFA elements to the RF generator, wherein the plurality of RFA elements are configured to generate respective elliptical ablation zones when powered by the RF generator.

2. The device of claim 1, wherein the longitudinally disposed RFA elements are uniformly spaced apart by a common interval.

3. The device of claim 2, wherein the plurality of RFA elements comprise a length of 20 millimeters.

4. The device of claim 3, wherein a powered RFA element of the plurality of RFA elements generates an elliptical ablation zone that longitudinally and proximally extends 4 millimeters.

5. The device of claim 3, wherein the powered RFA element generates an elliptical ablation zone that longitudinally and distally extends 5 millimeters.

6. The device of claim 5, wherein the common interval of 8 millimeters between adjacently powered RFA elements of the plurality of RFA elements provides an overlapping ablation zone.

7. The device of claim 2, wherein the plurality of RFA elements comprise a length of 15 millimeters.

8. The device of claim 7, wherein a powered RFA element of the plurality of RFA elements generates an elliptical ablation zone that longitudinally and proximally extends 3 millimeters.

9. The device of claim 8, wherein the powered RFA element generates an elliptical ablation zone that longitudinally and distally extends 4.3 millimeters.

10. The device of claim 9, wherein the common interval of 6 millimeters between adjacently powered RFA elements of the plurality of RFA elements provides an overlapping ablation zone.

11. The device of claim 2, wherein the plurality of RFA elements comprise a length of 10 millimeters.

12. The device of claim 11, wherein a powered RFA element of the plurality of RFA elements generates an elliptical ablation zone that longitudinally and proximally extends 1.3 millimeters.

13. The device of claim 12, wherein the powered RFA element generates an elliptical ablation zone that longitudinally and distally extends 4.3 millimeters.

14. The device of claim 13, wherein the common interval of 5 millimeters between adjacently powered RFA elements of the plurality of RFA elements provides an overlapping ablation zone.

15. The device of claim 2, wherein the plurality of RFA elements comprise a length of 7 millimeters.

16. The device of claim 15, wherein a powered RFA element of the plurality of RFA elements generates an elliptical ablation zone that longitudinally and proximally extends 1.5 millimeters.

17. The device of claim 16, wherein the powered RFA element generates an elliptical ablation zone that longitudinally and distally extends 2.9 millimeters.

18. The device of claim 17, wherein the common interval of four millimeters between adjacently powered RFA elements of the plurality of RFA elements provides an overlapping ablation zone.

19. The device of claim 1, wherein each RFA element of the plurality of elements is selectively powered by the RF generator.

20. The device of claim 1, wherein the intermediate section comprises 30 cm.

21. The device of claim 1, wherein the intermediate section provides couples the plurality of RFA elements to a water supply.

22. A method of ablating lesions in a column of bone using the device of claim 1, the method comprising placing the plurality of RFA elements within and along an intramedullary space of a long bone; powering the plurality of RFA elements using the RF generator, wherein the powered plurality of RFA elements are configured to generated a continuous tubular ablation zone along the intramedullary space.

23. The method of claim 22, wherein the bone includes a humerus, a tibia, and a femur.

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