Patent Description:
In patients suffering from late stage liver cirrhosis, a treatment that is commonly used is the creation of a TIPS (Transjugular Intrahepatic Portosystemic Shunt) shunt. Such a TIPS shunt is an artificial channel that is created between the hepatic and the portal vein and that allows for blood to bypass the liver. It has been shown that such shunts improve the life expectancy of patients diagnosed with liver cirrhosis since it is a treatment for portal hypertension (which is often due to liver cirrhosis) which frequently leads to intestinal bleeding, life-threatening esophageal bleeding (esophageal varices) and the buildup of fluid within the abdomen (ascites).

Such shunts are typically created by advancing a puncture needle through the patient's vasculature to the puncture site. A surgeon will then puncture the diseased liver tissue with the aim of the puncture reaching the portal vein. If the puncture attempt is unsuccessful, the needle is withdrawn from the patient's vasculature and will be reshaped, for example by manual bending.

Once the TIPS shunt has been created, a specialised TIPS stent graft is placed within the puncture so as to keep it open. Through that shunt, blood can bypass the liver, which ameliorates portal hypertension.

However, it is also to be noted that there are numerous other fields of surgery where puncture devices are needed. <CIT>, <CIT>, <CIT> and <CIT> disclose devices of the prior art.

The present inventor has realised that the creation of a TIPS shunt is often rather complicated. It is frequently the case that the surgeon does not manage to puncture the portal vein on the first attempt. Accordingly, the puncture needle needs to be withdrawn somewhat and rotated (or, in some cases, completely withdrawn and bent). Afterwards, another puncture attempt can be made. It is clear that the time consumption is significant. Furthermore, withdrawing the needle and manually bending it also comes with a risk of injuring the surgeon. Given that a patient's blood can contain pathogens such as viruses, it is thus highly desirable to reduce the number of times a TIPS puncture needle needs to be withdrawn.

It is also often difficult to rotate the puncture needle when inside the patient's vasculature. Diseased liver tissue is generally very congested, so that rotating a bent puncture needle inside the patient is difficult, if not impossible, due to a lack of space. Accordingly, the needle needs to be withdrawn to a less congested space, with a corresponding time consumption. Furthermore, the limited visualization of the space makes the procedure even more complicated.

The present invention aims at alleviating or even solving at least some of those problems.

Additional embodiments are described in the dependent claims. No surgical methods are claimed.

Embodiments described herein relate to a puncture device that is arranged for being advanced to a puncture site through the human vasculature. Accordingly, it needs to be sufficiently low profile and sufficiently flexible for such an advancement. In optional embodiments, the puncture device is sufficiently stiff for penetrating diseased liver tissue.

The puncture device comprises a puncture means which is that component of the puncture device that is meant for creating a puncture through tissue. Such a puncture means can take the form of a hollow needle. The puncture means has a pointed distal end that is arranged for creating a puncture in a patient's tissue.

Furthermore, a sheath is provided. This sheath surrounds the puncture means and has the puncture means slidably arranged inside the sheath. Accordingly, when the puncture device is used for puncturing tissue, and when it is thus inside the human body, the sheath can be slidably moved relative to the puncture means.

The puncture device furthermore comprises a tissue expansion means that is arranged so that it can be selectively activated, wherein when in the activated state, the tissue expansion means pushes away the patient's tissue to thereby allow a reorientation of the puncture means.

Accordingly, with the inventive puncture device, the tissue expansion means can push tissue away so as to create a space within which the puncture means can be reoriented. Thus, the orientation of the puncture means can be changed without having to completely withdraw the puncture means by activating the tissue expansion means and by then rearranging the puncture means, for example by rotating it. Such a puncture device allows for some degree of reorientation of the puncture means and hence minimizes the number of times the puncture device has to be withdrawn during use. This reduces the time required for the puncture procedure.

In embodiments, the tissue expansion means is slidably arranged inside the sheath and is arranged so that it can be slid out of the sheath so as to extend distally relative to the distal end of the puncture means. In that way, the tissue expansion means can be shielded from the outside of the puncture device by means of being inserted into the sheath, which therefore allows for a certain protection of the expansion means. Furthermore, the sheath can serve as a way of avoiding premature expansion of the expansion means by restraining it. The sheath can in particular be made of polyethylene terephthalate (PET) or polyether ether ketone (PEEK).

According to one embodiment, the tissue expansion means is arranged so as to expand when heated above a threshold temperature to thereby push away tissue. Such a heating up of the tissue expansion means can be achieved, for example by having a heating coil installed as part of the puncture device. Accordingly, this is an easy to implement way of actuating the tissue expansion means of the puncture device.

In some embodiments, the tissue expansion means comprises a shape memory alloy, e.g. nitinol. Such materials are well characterised and find wide application in the technical field of puncture devices and stent/stent grafts. Furthermore, they have good capabilities of creating implants that will expand when heated above a certain threshold temperature.

In that context, in embodiments, there is a means for selectively heating up the tissue expansion means. Such a means, which could take the form of or include a coil, is an easy to implement way of heating up tissue expansion means and can thus be used as a simple actuation mechanism.

In embodiments, the threshold temperature above which the expansion of a tissue expansion means occurs is higher than <NUM>, in embodiments higher than <NUM>, e.g. of about <NUM>. Transition temperatures of <NUM> or even <NUM> can also be used in the case of severely diseased liver. Each °C change from the transition temperature could change the radial forces by approximately <NUM> N/mm<NUM>. By having such a temperature threshold, premature expansion of the tissue expansion means due to heating to body temperature is avoided. Furthermore, choosing a transition temperature that is higher than body temperature ensures that an active heating of the tissue expansion means is needed to keep it in the activated state. Accordingly, if it is no longer desired to use the tissue expansion means, it suffices to no longer actively heat it. In that situation, it will cool down to body temperature and thus no longer be activated. Furthermore, in the context of shape memory alloys, it is known that the higher the transition temperature, the higher the resulting stiffness of the tissue expansion means and hence the higher the force it applies to surrounding tissue (cf. Accordingly, having a higher transition temperature leads to a higher force that is applied to the tissue to be pushed away, which increases the space available for reorienting the puncture means. Furthermore, the higher the difference between the transition temperature and body temperature, the easier it is to control the system. In embodiments, a temperature difference of more than <NUM> is envisaged.

In embodiments, the tissue expansion means has, in the activated configuration, a shape where the cross-sectional area of the tissue expansion means increases when moving from a proximal end to a distal end of the tissue expansion means. As used herein, the proximal end is closer to the handle of the puncture device which will be held by the surgeon, whereas the distal end is closest to the tip of the puncture device. By having such a shape where the cross-sectional diameter increases, the area over which a rearrangement of the puncture device can be achieved increases, which gives greater manoeuvrability for the puncture device.

In embodiments, the tissue expansion means can be brought back to its non-activated state (which a correspondingly reduced cross-sectional diameter) by means of advancing the sheath relative to the puncture device and thus relative to the tissue expansion means. This makes it easier to reduce the cross-sectional diameter of the tissue expansion means when needed.

In embodiments, the tissue expansion means comprises an expandable lattice structure similar to that of a stent. Since such stents have been well-characterised and are used widely in medicine, the generally well-known manufacturing techniques for such devices can also be supplied to such tissue expansion means.

According to an alternative embodiment, a puncture device comprises:.

<FIG> shows a puncture device according to a first embodiment of the present invention. The puncture device <NUM> comprises a puncture means <NUM> that has the form of a hollow needle having a lumen <NUM> extending longitudinally therethrough. This lumen <NUM> can be used for aspirating blood to check whether a puncture attempt has been successful.

Provided so as to surround the puncture means <NUM> is a tube <NUM>. This tube <NUM> serves to prevent the puncture means <NUM> from coming into contact with those components of the puncture device <NUM> that are further towards the outside.

The tube <NUM> is surrounded by a tissue expansion means <NUM> that has the shape of a tubular mesh work made of nitinol. The whole assembly of the puncture means <NUM>, tube <NUM> and tissue expansion means <NUM> is surrounded by a sheath <NUM>. The sheath <NUM> has, at its distal end, a flared-out distalmost end <NUM> that corresponds to a widening opening. The sheath <NUM> is slidable relative to the puncture means <NUM> as well as relative to the tube <NUM> and the tissue expansion means <NUM>.

<FIG> shows a longitudinal cross-section of what is shown in <FIG>. As can be seen, the puncture means <NUM> extends distally from the distal most ends of the sheath <NUM>, the tube <NUM>, and the tissue expansion means <NUM>. As can be furthermore seen, wires <NUM> are connected to a proximal end of the puncture device. Using electricity conducted through those wires <NUM>, a heating means (not shown) can be heated up which will cause the tissue expansion means <NUM> to heat up and to thus expand to thereby push away patient tissue surrounding it.

In <FIG>, some of the components described previously with respect to <FIG> have been shown. As can be seen, a sheath <NUM>, a tissue expansion means <NUM>, a tube <NUM> and a puncture means <NUM> are arranged inside the puncture device <NUM> which can, as shown in <FIG>, be arranged concentrically.

<FIG> shows a configuration in which the tissue expansion means <NUM> has been positioned distally relative to the sheath <NUM>. In that configuration, in which the tissue expansion means <NUM> has also expanded outwardly, the tissue expansion means <NUM> assumes a flared-out shape that is similar to a trumpet. The widest diameter portion is at that position of the tissue expansion means <NUM> that is furthest away from the sheath <NUM>. Any tissue that would surround the tissue expansion means <NUM> will be pushed away in the circumferential and/or radial direction, resulting in free space for reorienting the puncture means <NUM>. Accordingly, in that configuration, if a puncture attempt of the portal vein has been unsuccessful, the puncture means <NUM> can be reoriented, and another puncture attempt can be made.

What can also be seen from <FIG> are radiopaque markers <NUM> that are provided at the distalmost end of the tissue expansion means <NUM>. They serve to localise the tissue expansion means <NUM> inside a body and aid a surgeon in knowing where in the body the puncture device is arranged. They can be visualized using, for example, radiography. Such markers can use tantalum or gold as the radiopaque material. The radiopaque markers <NUM> aid in indirectly localizing the puncture means <NUM> since they surround the puncture means <NUM>.

The tissue expansion means <NUM> can be brought into this expanded state by means of proximally withdrawing the sheath <NUM> whilst activating the non-illustrated heating means by means of conducting electricity through the wires <NUM>. When the tissue expansion means <NUM> is heated above the transition temperature of nitinol, it will expand to its expanded state, which is illustrated in <FIG>. Any bodily tissue that surrounds the tissue expansion means <NUM> will thus be pushed away in the radial and/or circumferential direction. Accordingly, the puncture means <NUM> can be reoriented comparatively freely. It is to be noted that a portion of the tissue expansion means <NUM> stays underneath the sheath <NUM> even when the tissue expansion means <NUM> is expanded so as to aid in compressing and, finally, retracting it.

If the tissue expansion means <NUM> is to be reduced in its diameter, for example if it is to be withdrawn, it will be sufficient to advance the sheath <NUM> relative to the tissue expansion means <NUM> whilst also ensuring that heating means provided as part of the puncture device <NUM> is deactivated. The tissue expansion means <NUM> will quickly cool down so that it be comparatively easy retracted into the sheath <NUM>. The flared-out distalmost end <NUM> will act so as to aid in compressing the expansion means <NUM> so that it can be retracted and retained inside the sheath <NUM>. If need be, the tissue expansion means <NUM> can be redeployed as described in the previous paragraph.

<FIG> shows a puncture device <NUM>' according to a second embodiment of the invention. It is to be noted that the same reference numerals will be used that were also used when describing the first embodiment, and a detailed description of the corresponding components will be omitted.

As can be seen from <FIG>, the puncture means <NUM> does not have a uniform cross-section but becomes thinner at a thinning portion <NUM> when moving from the distal end of the puncture means <NUM> to the proximal end. Furthermore, the tube <NUM> has a flared-out portion <NUM> at its distal end. By the puncture means <NUM> becoming thinner at the thinning portion <NUM>, the distal end of the puncture means <NUM> can have a greater degree of bent, which gives a greater degree of freedom for a surgeon when reorienting it by rotating the puncture means <NUM> as indicated by the arrow. The flared-out portion <NUM> makes it easier to retract the puncture means <NUM> into the tube <NUM>. The maximum degree of freedom is defined by the angle between the expanded tissue expansion means <NUM> and the center line (which is indicated by a dashed line).

<FIG> shows exemplary steps in the use of the puncture device.

As a first step (step S110), the puncture device is advanced, typically through a patient's vasculature, to an intended puncture location.

Subsequently (step S112), the surgeon attempts a puncture. If desired, it can be checked whether the puncture was successful by means of aspirating blood through a lumen of the puncture means of the puncture device. If successful, further procedures such as the placement of a device such as the TIPS stent graft take place.

If, however, the puncture attempt is unsuccessful, in step S114, the tissue expansion means is expanded so as to push away tissue to thereby create a space for reorienting the puncture means.

Subsequently (step S116), the puncture means is reoriented and brought into a position that is, in the surgeon's assessment, more likely to result in a successful puncture.

Subsequently (step S118), another puncture attempt is made. If this step is unsuccessful, steps S116 and S118 can be performed repeatedly, until the surgeon succeeds in puncturing the blood vessel to be punctured. Subsequently (not shown in the flow chart), once the shunt has been created, the tissue expansion means <NUM> is retrieved, as is the rest of the puncture device, whilst typically leaving a guidewire in place to aid in placing an implant.

Claim 1:
Puncture device (<NUM>) that is arranged for being advanced to a puncture site through the human vasculature, the puncture device comprising:
- a puncture means (<NUM>), the puncture means comprising a distal end that is arranged for creating a puncture in a patient's tissue,
- a sheath (<NUM>), the sheath (<NUM>) being arranged so as to surround the puncture means (<NUM>), the puncture means (<NUM>) being slidably arranged inside the sheath (<NUM>),
- a tissue expansion means (<NUM>), the tissue expansion means (<NUM>) being arranged so that it can be selectively activated, wherein in the activated state, the tissue expansion means (<NUM>) pushes away the patient's tissue to thereby allow a re-orientation of the puncture means (<NUM>), the tissue expansion means (<NUM>) being arranged so as to expand when heated above a threshold temperature to thereby push away tissue, the tissue expansion means (<NUM>) comprising a shape memory alloy.