VEIN ABLATION

Abstract

The present invention relates to a method of ablating a vein in a subject. The method comprises introducing an ablation member into the vein, wherein the ablation member has an external diameter of less than 5 French Gauge (FG); and emitting thermal energy with a power output of less than 5.5 Watts from the ablation member to thereby ablate the vein.

Claims

1. A method of ablating a vein in a subject, the method comprising: introducing an ablation member into the vein, wherein the ablation member has an external diameter of less than 5 French Gauge (FG); and emitting thermal energy with a power output of less than 5.5 Watts from the ablation member to thereby ablate the vein.

2. The method according to claim 1, wherein the vein is disposed in the subject's forehead.

3. The method according to claim 2, wherein the ablation member is advanced along the vein until a first end of the ablation member is disposed substantially adjacent to the top of the nose and/or between the eyebrows of the subject.

4. The method according to claim 1, wherein the method initially comprises placing the subject in a head down position, where the subject's heart and legs are above the subject's forehead.

5. The method according to claim 1, wherein the method comprises: introducing a needle comprising a channel into the vein, thereby creating an aperture in the patient's skin; passing a guidewire through the channel of the needle, and thereby introducing it into the vein, and then removing the needle from the vein; disposing a cannula over a dilator comprising a channel; feeding the guidewire into the channel of the dilator, and thereby dilating the aperture and introducing the dilator and cannula into the vein; removing the dilator and guidewire from the vein; and introducing the ablation member into the vein comprises passing the ablation member through the cannula into the vein.

6. The method according to claim 1, comprising administering at least one of a local anaesthetic, bicarbonate and/or adrenaline to the subject adjacent to the vein.

7. The method according to claim 1, comprising locating the subject in a head-up position, where the subject's heart and legs are below the subject's forehead, after the ablation member is introduced into the vein.

8. The method according to claim 1, comprising moving the ablation member along the vein as the thermal energy is emitted at a speed of between 1 and 20 s/cm, or between 2 and 15 s/cm, or between 3 and 12 s/cm, or between 4 and 11 s/cm, or between 5 and 10 s/cm, or between 6 and 8 s/cm, and/or holding the ablation member stationary in the vein as the thermal energy is emitted.

9. The method according to claim 1, wherein the thermal energy is provided as a laser beam.

10. The method of claim 9, wherein the laser beam has a wavelength between 750 and 2500 m, optionally between 1600 and 2300 nm.

11. The method according to claim 1, wherein the thermal energy is emitted from the ablation member at a power output of between 0.5 and 5.5 Watts, between 1 and 5 Watts, between 1.5 and 4.5 Watts or between 2 and 4 Watts, and/or wherein the power output is measured at a first end of the ablation member.

12. The method of claim 1, wherein the method comprises delivering between 10 and 30 joules of energy per centimetre of vein.

13. The method according to claim 4, wherein the needle is introduced into the vein using an imaging technique, optionally wherein the imaging technique is ultrasound guidance.

14. The method according to claim 4, wherein the needle is inserted at an angle between 10° and 90°, between 20° and 70°, between 30° and 60°, or between 40° and 50° relative to the subject's skin.

15. The method according to claim 4, wherein the needle has a gauge of between 10 and 30 G, or between 12 and 25 G, or between 15 and 21 G.

16. The method according to claim 6, wherein the local anaesthetic, bicarbonate and/or adrenaline is administered after the cannula and/or the ablation member are introduced into the vein.

17. The method according to claim 6, wherein the volume of the at least one of local anaesthetic, bicarbonate and/or adrenaline administered is between 0.1 and 50 ml, between 0.5 and 10 ml, between 1 and 5 ml, between 1.25 and 3 ml, or between 1.5 and 2.5 ml per cm of vein to be treated.

18. The method according to claim 1, wherein the method comprises cooling the skin over the vein after the ablation member is introduced into the vein, optionally wherein the method comprises cooling the skin using a cold air blower.

19. The method according to claim 1, wherein the ablation member has an external diameter of between 1 and 5 FG, between 1.5 and 4.75 FG, between 2 and 4.5 FG, between 2.5 and 4 FG or between 3 and 3.5 FG.

20. The method according to claim 4, wherein the cannula comprises a first end and a second end defining a channel there between, wherein the cannula has an external diameter of less than 20 FG, an internal diameter which is at least as large as the external diameter of the ablation member and a length of less than 4.5 cm.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0063] For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the accompanying Figure, in which:

[0064] FIG. 1A shows a front view of a subject's head showing the typical anatomy of their forehead veins;

[0065] FIG. 1B shows a front view of a further subject's head showing the typical anatomy of their forehead veins;

[0066] FIG. 1C shows a front view of a still further subject's head showing the typical anatomy of their forehead veins;

[0067] FIG. 2 is a schematic side view of an embodiment of a vein ablation apparatus according to the invention, comprising an introduction cannula, a laser fibre and a dilator;

[0068] FIG. 3 is a cross-sectional side view of a section of a subject's forehead comprising a vein;

[0069] FIG. 4 shows a subject placing their hands on their cheeks so that they are resting next to the nose, creating pressure so that the forehead veins become more prominent—a manoeuvre previously published as the “Whiteley-Smith” sign;

[0070] FIG. 5 illustrates a subject on an operating table in the Trendelenburg position;

[0071] FIG. 6A illustrates a first step in a method of ablating forehead veins using the vein ablation apparatus shown in FIG. 2. As shown in the Figure, in the first step a hollow needle is inserted through the skin of the patient and passed into the vein to be treated;

[0072] FIG. 6B illustrates a second step in the method of ablating forehead veins, where a guidewire is passed through the channel of the needle;

[0073] FIG. 6C illustrates a third step in the method of ablating forehead veins, where the needle is removed;

[0074] FIG. 6D illustrates a fourth step in the method of ablating forehead veins, where a dilator is disposed with a cannula, and both are passed over the guidewire;

[0075] FIG. 6E illustrates a fifth step in the method of ablating forehead, where the dilator slightly enlarges the tract originally produced by the needle and enables the cannula to be placed within the vein;

[0076] FIG. 6F illustrates a sixth step in the method of ablating forehead veins, where the dilator and guidewire are removed leaving the cannula in position;

[0077] FIG. 6G illustrates a seventh step in the method of ablating forehead veins, where a slim laser fibre is passed through the cannula, down the vein, and is positioned with the tip at the top of the nose between the eyebrows;

[0078] FIG. 6H illustrates an eighth step in the method of ablating forehead veins, where local anaesthetic is injected around the vein; and

[0079] FIG. 7 shows cross-sectional views of a skin incision made using a hollow needle at both a 90 degree (A) and 45 degree angle (B) to the surface of the skin.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Examples

[0080] Referring first to FIG. 1, there are shown front views of three different subjects' heads 1a, 1b and 1c, showing the typical anatomy of their forehead veins 4.

[0081] An apparatus 22 for ablation of prominent forehead veins 4 is shown in FIG. 2, comprising an introduction cannula 26 and a laser fibre 24.

[0082] As shown in FIG. 2, the laser fibre 24 is an elongate member extending between a first end 25 and a second end (not shown). Due to the size of forehead veins, the laser fibre 24 would have a relatively small diameter, of about 3-4 FG (French Gauge).

[0083] The laser fibre 24 comprises a plastic coating 30 extending between the first end 25 and the second end. The plastic coating 30 coating defines a tip defining rounded or pointed shape at the first end, configured to aid insertion of the laser fibre 24. The plastic coating further defines an air bubble 34, disposed within or adjacent to the tip of the plastic coating 30.

[0084] The laser fibre 24 further comprises an optical fibre 28 and a source of thermal energy, such as a laser source (not shown). The optical fibre 28 is an elongate member disposed within the plastic coating and extends between a second end (not shown) and a first end 31. The second end of the optical fibre 28 is substantially adjacent to the second end of the laser fibre 24 and is connected or connectable to the laser source. The first end 31 of the optical fibre 28 is disposed in the air bubble 34. In some examples, the first end 31 of the optical fibre is in the shape of a cone 31, ensuring that the laser beam emerges from the tip radially. Accordingly, laser light may be emitted in a 360 degree range around the circumference of the fibre into the surrounding vein wall. This is enhanced by the shape of the first end 25 of the laser fibre 24 and the air bubble 34.

[0085] In one embodiment, the laser used for this technique is a diode laser. However, in other embodiments, the laser could be a crystal laser or liquid crystal laser. In addition, fibres other than a radial fibre could be used to perform this technique. For example, this method may be performed using a bare fibre, a forward firing fibre, a jacket-tipped fibre, a two ring radial fibre or a three ring radial fibre.

[0086] In other embodiments, the source of thermal energy source may not be a laser source. For example, a radiofrequency source may be used to generate radiofrequency radiation for the ablation of forehead veins. Alternatively, electromagnetic radiation or steam sclerotherapy may be used.

[0087] The cannula 26 is an elongate, tubular member, and is configured to enter a forehead vein of a subject. That is, the cannula may be dimensioned such that it may be inserted into a subject's vein. The standard cannula used for veins of the leg needs to pass through the skin and various layers of subcutaneous fat at an angle. Consequently, the cannula for ablation of leg veins is approximately 10 cm long, but can range from 5 cm to 50 cm or more. However, as a forehead vein can be quite short, in the region of 2-7 cm, and is very near the surface of the skin, the standard length cannula used for leg vein ablation may not be appropriate for this treatment. Therefore, the cannula 26 need only be very short, and can be in the region of 1-3 cm. The cannula 26 and laser fibre 24 are sized such that the laser fibre 24 may be reversibly disposed within the cannula 26. Accordingly, the internal diameter of cannula may be 3-4 FG. The external diameter of the cannula may be 3-6 FG. In contrast, the standard cannula used in leg vein ablation has an internal diameter of approximately 6 FG.

[0088] The apparatus 22 may further comprise a dilator 40. The dilator 40 comprises an elongate member 47 extending between a first end 39 and a second end 41. A channel 43 extends through the elongate member 47 between the first and second ends 39, 41. The elongate member 47 is sized such that it may be reversibly disposed within the cannula 26. Accordingly, it may have a diameter of 3-4 FG. The second end 41 of the elongate member 40 comprises a handle 45 sized to prevent the second end 41 of the elongate member 47 from passing through the cannula 26. The first end 39 of the elongate member 39 defines a pointed end configured to be inserted into and enlarge an aperture in a body. The first end 39 of the dilator 40 need only stand proud from a first end of the cannula 26 by approximately 1 cm. Conversely, a dilator used for leg veins should stand proud of a cannula by about 2-3 cm. If the dilator 40 is too long it could be difficult to position the cannula 26 within the forehead vein 4. Accordingly, the length of the elongate member 40 may be about 1 cm longer than the length of the cannula, i.e. it could be about 2 to 4 cm long.

[0089] When working with humans or animals, it is essential to maintain a sterile environment. Particularly, if an instrument is not sterile, the bacteria that may have collected on the instrument can be transferred to a tissue, cause infection. Therefore, medical instruments need to be easy to sterilise, or designed for one-time use. Sterilising instruments typically involves heating the instrument using steam in an autoclave. Clearly, this is not appropriate for instruments having electrical components. Methods of sterilization also include using gamma radiation and Ethylene Oxide (EtO) treatment, but these are costly and labour-intensive.

[0090] Therefore, in one embodiment, the cannula may be disposable. At least a portion of the plastic coating 30 comprising the tip may also be disposable. This prevents wastage of the optical fibre 28, which has not come into contact with a human or animal. The cannula and/or portion of the plastic coating may be encased in a sterile air-tight package prior to use.

[0091] To perform the procedure, a subject 18 is placed on the operating table 20. Although it is possible to do this with the patient supine, it is advantageous to place the patient in a head down position, known as the Trendelenburg position (FIG. 5). In this position, the heart and legs are above the forehead veins, making the veins more obvious and tense as they fill with venous blood. Consequently, the veins do not collapse when the initial part of the procedure is performed.

[0092] Alternatively or additionally, if, while the patient is sitting or standing, the central forehead veins are not visible, the patient may place their hands 16 on their cheeks so that they are resting next to the nose 8, as seen in FIG. 4. This pressure blocks draining of the facial veins and as a result, the forehead veins 4 become more prominent.

[0093] FIG. 6 illustrates a method of ablating forehead veins 4 using the vein ablation apparatus 22 and the Seldinger technique. It is possible to gain access to the veins with a variety of techniques. A direct intravenous cannulation can be performed using a cannula and needle combination (i.e. a standard intravenous cannulation). However, a Seldinger technique, as described below, is likely to be more successful.

[0094] A subject's skin 10 is prepared and any sterile drapes are put in position. FIG. 3 illustrates a cross-sectional side view of a forehead vein, in which the vein 4 is positioned within the frontalis muscle 12, that is located between the skin 10 and the skull bone 14. As shown in FIG. 6a, a hollow needle 36 is inserted through the skin and passed into the vein to be treated 4. As the vein of the forehead is short and small, it is optimal to use a very thin needle between 21-31 gauge. The needle 36 is inserted as high up on the scalp and as close to or above the hairline as is possible. The needle 36 may be inserted using direct vision or an imaging technique such as ultrasound guidance.

[0095] It may be advantageous to make a small skin incision at an angle to facilitate the passage of both the initial needle and the subsequent dilator. This angle is approximately 45° to the perpendicular and is slanted in the direction of the needle passing into the vein (FIG. 7). The incision is positioned this way because the skin of the forehead is tough. Making the slanted incision allows the needle and subsequent dilator to be passed directly into the vein without excessive resistance.

[0096] In addition, by making the incision at an angle to the perpendicular, healing is much improved and scars are far more likely to be cosmetically acceptable or even invisible. This is because an incision through the skin at an angle to the perpendicular, creates a very small surface area for healing, reducing the amount of scar tissue visible on the surface.

[0097] Alternatively, the inventors have found that it is possible to insert a dilator and cannula using the Seldinger technique through a single needle hole. Accordingly, a preliminary incision is not essential.

[0098] If a bare fibre or very thin laser fibre are being used, the Seldinger approach may be replaced by simple insertion of a hypodermic needle. A hypodermic needle, such as a 21 gauge needle, can be passed directly into the vein and a bare fibre or other similar very fine laser fibre can be passed directly through this hypodermic needle and into the vein.

[0099] Alternatively, if the Seldinger approach is followed, a guidewire 38 is then passed through the channel of the needle 36 (FIG. 6b), and once in place, the needle 36 is removed (FIG. 6c). Next, the dilator 40 is disposed with the cannula 26, and both are passed over the guidewire. The dilator 40 slightly enlarges the tract originally produced by the needle 36 (FIG. 6d) and enables the cannula to be placed within the vein 4 (FIG. 6e). Finally, the dilator 40 and the guidewire 38 are removed from the patient leaving the cannula 26 in position (FIG. 6f).

[0100] Once the cannula 26 is within the vein 4 to be treated, the slim laser fibre 24 is passed through the cannula 26, down the vein 4, and is positioned with the tip at the top of the nose between the eyebrows (FIG. 6g). There may be one vein or multiple veins that need treatment and so this process can be repeated for any number of veins that are being treated.

[0101] Once the cannula 26, and preferably also the laser fibre 24, are in place local anaesthetic 44 is injected around the veins (FIG. 6h). Bicarbonate can be added to the local anaesthetic to reduce pain and adrenaline (epinephrine), and to increase constriction of the vein around the fibre, thereby removing any venous blood still within the vein. A sufficient volume is used to separate the veins from the skin and skull, using the concept of “tumescence”. This protects the skin, skull and any other surrounding structures from thermal damage.

[0102] At this stage, it is advantageous to tip the patient into a “head-up” (reverse-Trendelenburg) position, further reducing the chance of any blood being in the vein during treatment. In addition, it is also useful to cool the skin 42 overlying the vein during treatment to reduce the risk of any skin damage or burns.

[0103] Once the patient is in an optimum position with tumescence in place and cooling of the skin, if required, the laser is fired producing continuous output energy at 1470 nm or 1940 nm and a constant power output of 2-4 Watts, preferably 3 Watts.

[0104] A power of between 2-4 Watts, and more specifically 3 Watts is optimal, with lower powers not causing enough damage to the vein and higher powers causing damage to the skin or surrounding structures. Comparatively, a power of 6-12 Watts is required in the ablation of leg veins.

[0105] The use of a laser with a wavelength of 1940 nm is advantageous because the chromophore of this wavelength is water. It is possible to use other wavelengths, however it is clear that those which use water as the chromophore have a significant advantage over those that use haemoglobin or other chromophores. Additionally, since a wavelength of 1940 nm has a higher affinity for water, heat does not spread as far out from the vein, resulting in a safer treatment as the risk of skin burns is reduced.

[0106] The optimal power output of 3 Watts is selected with the aim of delivering power between 18-24 joules per centimetre of vein, and more preferably between 20-22 joules per centimetre of vein. Energy transference to the vein wall is determined by the pullback speed. A pullback speed of seven seconds per centimetre is optimal. However, this may vary depending on the size and circumference of the vein and therefore, pullback can range from 3-12 seconds per centimetre.

[0107] Once the whole length of the vein or each vein has been treated, the skin is closed with glue or a simple plaster.

[0108] Advantages of the apparatus of the invention reside in the ability to carry out endovenous ablation of much smaller veins of the forehead, compared with the apparatus that is currently used for endovenous ablation of much larger veins of the leg. The shorter introduction cannula (1-3 cm) of the apparatus allows entry into small forehead veins, positioned close to the surface of the skin. In contrast, the apparatus for leg vein ablation comprises a much longer introduction cannula which would be very difficult to position within a vein of the forehead. In addition, the small diameter laser fibre of the apparatus can enter much smaller veins of the forehead and emit laser energy at a much lower power. This is very advantageous, since the leg vein ablation apparatus has a laser fibre with a diameter that is too large for entering forehead veins and emits laser energy at a much higher power which would cause damage to the skin of the forehead.