Balloon dilation device

The invention related to a balloon dilation device having a distal end and a proximal end. The balloon dilation device comprises a handle, a shaft, an inflatable balloon and at least one sensor coil. The handle extends from the proximal end of the balloon dilation device towards the distal end of the balloon dilation device. The shaft extends from the distal end of the balloon dilation device towards the proximal end of the balloon dilation device, said shaft having an inflation lumen. The inflatable balloon is fixedly arranged at the shaft. The balloon is fluidly connected to the inflation lumen such that the balloon can be inflated and deflated by feeding a fluid through the inflation lumen into the balloon. The at least one sensor coil is arranged at the shaft. The at least one sensor coil is configured for capturing an electromagnetic field and for providing a sensor coil signal representing position and orientation of the sensor coil.

TECHNICAL FIELD

The invention relates to a balloon dilation device, a medical system comprising a balloon dilation device and a method for determining position and orientation of a balloon dilation device.

BACKGROUND OF THE INVENTION

Balloon dilation refers to the dilation of a cavity or passageway of a human body with a balloon.

By way of example, the human skull comprises a group of four paired air-filled spaces known as paranasal sinuses that surround the nasal cavity. Each of the paranasal sinuses opens into the nasal cavity via small orifices.

Normal drainage of mucus from these paranasal sinuses can be interrupted or even become blocked which can result in an infection of the mucus membrane known as sinusitis.

Sinusitis can be treated, e.g., by means of balloon sinuplasty. Sinuplasty often includes using a balloon over-a-wire catheter to dilate sinus passageways to restore the normal drainage. Typically, in sinuplasty a flexible guide wire is inserted through the nostril and guided to a sinus cavity. For correct placement of the guide wire in the sinus cavity, often guide wires are used that have a light source at their tip for emitting light that can be seen by a surgeon through the patient's skin. The surgeon can thus follow the guide wire tip through the skin of a patient. After positioning of the guide wire, a balloon catheter is advanced over the guide wire and positioned in the blocked sinus cavity. When the balloon catheter is positioned in the sinus cavity, its balloon is inflated to dilate the sinus openings and to restore normal drainage.

Balloon catheters that include a movable shaft and methods for treating a sinus cavity of a subject with such a balloon catheter are described inter alia in U.S. Pat. No. 10,022,525 B2 and US 2017/0028112 A1.

A passageway in the human skull that can be dilated with a balloon is the Eustachian tube which links the nasopharynx to the middle ear. Normally, the Eustachian tube is closed, however, it can open, e.g., during swallowing. In its open state the Eustachian tube can provide pressure equalization between the middle ear and the atmosphere. Another function of the Eustachian tube is to drain mucus from the middle ear. The function of the Eustachian tube can be disrupted, e.g., by swelling or by blockage, e.g., as a result of a cold or allergies. If the function of the Eustachian tube is disrupted, e.g., caused by a disease of the middle ear such as otitis media, the Eustachian tube can be dilated with a balloon of a balloon dilation catheter to restore normal drainage and to achieve pressure equalization.

A method for dilating a Eustachian tube of a patient with a dilation device is described, e.g., in US 2010/0274188 A1. A device including a guide catheter and a balloon dilation catheter for dilating a Eustachian tube of a patient is disclosed in US 2018/0296811 A1.

SUMMARY OF THE INVENTION

It is an object to provide an improved balloon dilation device, to provide an improved medical system comprising a balloon dilation device and to provide an improved method for determining position and orientation of a balloon dilation device.

Regarding the balloon dilation device, the object is achieved by a balloon dilation device having a distal end and a proximal end. The balloon dilation device comprises a handle, a shaft, an inflatable balloon and at least one sensor coil. The handle extends from the proximal end of the balloon dilation device towards the distal end of the balloon dilation device. The shaft extends from the distal end of the balloon dilation device towards the proximal end of the balloon dilation device, said shaft having an inflation lumen. The inflatable balloon is fixedly arranged at the shaft. The balloon is fluidly connected to the inflation lumen such that the balloon can be inflated and deflated by feeding a fluid through the inflation lumen into or out of the balloon. The at least one sensor coil is arranged at the shaft. The at least one sensor coil is configured for capturing an electromagnetic field and for providing a sensor coil signal representing position and orientation of the sensor coil.

The balloon dilation device according to the invention is suitable for dilating a sinus cavity and the Eustachian tube of a patient. The balloon dilation device does not need to be modified in order to dilate either a sinus cavity or a Eustachian tube. For dilating a sinus cavity or for dilating a Eustachian tube, the balloon dilation device can be inserted through the nostril of a patient and guided to either the sinus cavity or a Eustachian tube.

The invention includes the recognition that a balloon dilation device such as a balloon catheter has to be guided through the human body in minimal invasive surgery and positioned in a sinus cavity before inflating the balloon. For positioning the balloon dilation device in a sinus cavity, commonly, first, a guide wire has to be inserted into the human body over which, in a second step, the balloon dilation device is advanced. A typical guide wire used in sinuplasty has a light source at its tip. To find the sinus cavity with the guide wire, the surgeon, typically, has to rely on a light spot as seen from outside through the skin. Thus, the surgeon cannot follow the guide wire or balloon dilation device inside the human body while guiding the guide wire or balloon dilation device.

Since the balloon dilation device according to the invention is equipped with at least one sensor coil, position and orientation of the balloon dilation device in relation to a human body can be determined by means of an electromagnetic position detection system. For determining position and orientation of the balloon dilation device, position and orientation of the at least one sensor coil are determined with the position detection system. Based on the determined position and orientation of the at least one sensor coil, position and orientation of the balloon dilation device can be calculated. With a position detection system, positions of the at least one sensor coil can be determined while moving the at least one sensor coil relative to, e.g., a field generator generating an electromagnetic field. From repeatedly determined positions of the at least one sensor coil, positions of the balloon dilation device moved relative to a position detection system can be determined and, thus, the position of the balloon dilation device can be tracked while guiding the balloon dilation device.

For example, for determining position and orientation of the at least one sensor coil, an electromagnetic position detection system can be used that comprises a field generator for generating an alternating electromagnetic field.

When exposing the balloon dilation device equipped with the at least one sensor coil to an alternating electromagnetic field, a current is induced in the at least one sensor coil. The current induced in the at least one sensor coil depends on the position and orientation of the sensor coil in the alternating electromagnetic field. Thus, from a sensor coil signal representing the induced current, position and orientation of the at least one sensor coil can be determined. When knowing the spatial relation between the balloon dilation device and the at least one sensor coil, e.g., the relative distance from the distal end of the balloon dilation device to the at least one sensor coil, position and orientation of the balloon dilation device can be calculated by a position detection system based on the detected position and orientation of the at least one sensor coil.

For supporting a surgeon in navigating the balloon dilation device, e.g., inside a patient's body, position and orientation of the balloon dilation device equipped with at least one sensor coil can be detected by means of such a position detection system and the position of the balloon dilation device can be displayed in sectional images of a patient's body part obtained, e.g., by tomography. Thus, the surgeon using the balloon dilation device according to the invention can follow the position of the balloon dilation device inside a human body on a monitor displaying sectional images and a digital representation of the balloon dilation device while guiding the balloon dilation device through the human body. Advantageously, a surgeon can adapt the way of the moving the balloon dilation device, e.g., an applied pressure or an angle of the balloon dilation device to a body part, according to the determined actual position and orientation of the balloon dilation device inside the human body.

Advantageously, since position and orientation of the balloon dilation device equipped with at least one sensor coil can be directly tracked with a position detection system, initially using a guide wire for finding a cavity becomes obsolete. Thus, with the balloon dilation device according to invention the number of steps necessary to position a balloon dilation device in a balloon cavity can be reduced and likewise surgery time can be saved.

In the following preferred embodiments of the balloon dilation device according to the invention are described.

Within the framework of this specification a fluid can be a gas or a liquid. Thus, for inflating the balloon either a gas, e.g., air, can be fed into the balloon through the inflation lumen or a liquid can be fed into the balloon through the inflation lumen. When inflating the balloon, balloon and inflation lumen are in fluid communication. Likewise, through the lumen the fluid inside the balloon can be removed, i.e., fed out of the balloon, to deflate the balloon.

It is advantageous if the handle comprises an attachment for attaching a fluid source to the inflation lumen, e.g., via a tube, for feeding a fluid through the inflation lumen into the balloon. The inflation lumen can extend from said attachment for attaching a fluid source through the handle and the shaft up to a connecting point where the balloon is fluidly connected to the inflation lumen.

It is preferred that the balloon is fixedly arranged at the shaft such that the balloon cannot be shifted along the shaft in longitudinal direction.

Preferably, the shaft is attached to the handle. For example, the shaft can extend at least through a part of the handle. The shaft can also extend through the handle along the full length of the handle up to the proximal end of the balloon dilation device.

Preferably, the shaft has a length between 80 mm and 220 mm. It can be advantageous if the shaft has a length that is between 90 mm and 180 mm. For various applications it is beneficial if shaft has a length that is between 110 mm and 140 mm, e.g., 130 mm. The shaft length refers to the distance between the distal end of the balloon dilation device and the distal end of the handle and, thus, refers to the visible part of the shaft.

In particular, the shaft can have an outer diameter between 1.2 mm and 1.8 mm. It is advantageous if the shaft has an outer diameter that is between 1.2 mm and 1.6 mm. For various applications it is beneficial if the shaft has an outer diameter that is between 1.2 mm and 1.4 mm. It is possible that the shaft has various sections, the sections having different outer diameters. For example, if the shaft has a malleable tip region, in the malleable tip region the shaft can have an outer diameter that is smaller than the outer diameter of the rest of the shaft. The shaft can be made of one piece, e.g., one hypo tube. It is also possible that the shaft comprises different pieces, e.g., two hypo tubes having different outer diameters that are chosen such that one hypo tube can be arranged at last partly inside the lumen of the other hypo tube.

A shaft with the dimensions specified above is suitable for being inserted into a nostril and guided to a sinus cavity or a Eustachian tube also with a deflated balloon being arranged at the shaft.

The shaft can comprise at least one hypo tube that is made of, e.g., polytetrafluoroethylene (PTFE), steel or nitinol. Typically, a hypo tube is a long metal tube with micro-engineered features along its length that shall provide the desired mechanical properties of the hypo tube. If the shaft comprises more than one hypo tube, the hypo tubes can be made of different materials.

It is preferred that the shaft is configured such that external forces as to be expected during use of the balloon dilation device do not cause a plastic deformation of the shaft. Accordingly, the shaft shall not deform plastically when exposed to external forces having a magnitude typically occurring when the shaft is inserted into a cavity or passageway. However, the shaft can be configured such that it deforms elastically when an external force typically occurring during surgery is exerted on the shaft. In this case, after release of the force the shaft returns to its rest position.

The handle, preferably, has a length that is between 100 mm and 200 mm, preferably, between 120 mm and 130 mm. For various applications it is advantageous if the shaft and the handle have a similar length.

From its distal end to its proximal end the balloon dilation device can have a total length that is between 180 mm and 440 mm. However, it is preferred that the total length of the balloon dilation device is between 200 mm and 300 mm.

It is particularly preferred that the shaft has a malleable tip region extending from a distal end of the balloon dilation device towards the proximal end of the balloon dilation device. If the shaft has a malleable tip region the inflatable balloon, preferably, is fixedly arranged at the shaft in the malleable tip region. It is preferred that the balloon is arranged in the malleable tip region adjacent to the distal end of the balloon dilation device.

In particular, a shaft with the dimensions (length and diameter) as specified above can have a malleable tip region extending from a distal end of the balloon dilation device towards the proximal end of the balloon dilation device in which the balloon is fixedly arranged.

The malleable tip region can have a length of between 10 mm and 60 mm. It is advantageous if the length of the malleable tip region is between 20 mm and 50 mm. In various embodiments, the malleable tip region has a length of between 25 mm and 35 mm, e.g. 30 mm. The length of the malleable tip region is included into the length of the shaft and, thus, does not add to the shaft length. In particular, in the malleable tip region, the shaft can have an outer diameter that is smaller than the outer diameter in the rest of the shaft.

The malleable tip region can be produced, e.g., by treating the shaft with heat. For example, if the shaft comprises a hypo tube that is made of steel, the shaft can be annealed at its distal end for fabricating the malleable tip region. For example, if the shaft is made of one piece, the shaft can be annealed in a selected region, e.g., in a region adjacent to the tip of the balloon dilation device, to produce the malleable tip region.

That the shaft can comprise a completely annealed inner hypo tube and an outer hypo tube. The inner hypo tube can be at least partly arranged inside a lumen of the outer hypo tube. Thus, the inner hypo tube can extend only partly into the lumen of the outer hypo tube or can extend along the full length of the outer hypo tube. Preferably, the outer hypo tube is attached to the handle.

Preferably, the length of the outer hypo tube is shorter than the total length of the shaft. In particular, it is preferred that the outer hypo tube ends before the distal end of the balloon dilation device. In case the outer tube ends before the distal end of the balloon dilation device it is preferred that at least a part of the inner hypo tube extends from the distal end of the outer hypo tube to the distal end of the balloon dilation device. Thus, the total length of the shaft is the sum of the lengths of the visible parts of the inner and outer hypo tubes.

That part of the inner hypo tube that extends from the distal end of the outer hypo tube to the distal end of the balloon dilation device, i.e., the visible part of the inner hypo tube, preferably, forms the malleable tip region of the shaft. An advantage of a shaft that comprises an inner hypo tube that is completely annealed and an outer hypo tube that is configured to not to deform plastically under an external force typically acting on the shaft when being guided through the human body is, that the length of the malleable tip region can be designed with high accuracy. Thus, the starting point of the malleable tip region can be selected and implemented very accurately.

In case the shaft comprises an inner and an outer hypo tube, the balloon of the balloon dilation device, preferably, is attached to the inner hypo tube, only.

After annealing, i.e., after heat treatment, the malleable tip region of the shaft, preferably, is made from a material having an ultimate tensile strength of up to 750 Nmm−2. It is also possible that the shaft comprises a different material or material composition in the malleable tip region as in the rest of the shaft. However, it is preferred that the shaft is made of only one material or material composition and that the malleable tip region is produced by heat treatment of the shaft in that region.

Preferably, in the malleable tip region the shaft can be deformed plastically without modifying the shape of the rest of the shaft. Thus, the shape of the malleable tip region of the shaft can be designed in a way that is suitable for surgery with the balloon dilation device. For example, it is preferred that an angle is formed in the malleable tip region of the shaft. Accordingly, the tip of the shaft can be arranged at an angle with respect to the rest of the shaft. During surgery, the shaft can be rotated to position the tip of the shaft at an angle suitable for entering a certain passageway, e.g. a passageway branching off a first passageway.

For plastically shaping the malleable tip region of the shaft and, thus, for implementing a new rest position of the malleable tip region, an external force can be exerted on the malleable tip region of the shaft that is sufficient to deform the malleable tip region of the shaft plastically.

Preferably, the amount of external force required to be exerted at the malleable tip region of the shaft in order to change the malleable tip region shape with respect to the rest of the shaft, still, is greater than a force that typically acts on the shaft during insertion into the sinuses. Thus, after the malleable tip region of the shaft is formed into the desired shape, the malleable tip region will not plastically change shape during insertion into the desired sinus cavity. Elastic deformation of the malleable tip region may occur, however, while using the device.

If the malleable tip region of the shaft can only be deformed when an external force is applied that is larger than forces typically occurring during surgery, while inserting the shaft into a cavity or passageway the malleable tip region of the shaft is deformed elastically, only. Thus, after releasing an external force during surgery the malleable tip region of the shaft returns to its prior defined rest position.

For the plastically shaping of the malleable tip region of the shaft into a desired shape, an external shaping tool can be used. A shaping tool can comprise a region for inserting the malleable tip region of the shaft. Such shaping tool can be used to apply an external force to the malleable tip region of the shaft for shaping of the malleable tip region of the shaft with respect to the rest of the shaft. Preferably, the shaping tool comprises a number of pre-fixed shaping position options for shaping the malleable tip region of the shaft into one of the pre-fixed shapes. Such pre-fixed shape positions can be defined for a suitable angle degree needed for accessing, e.g., particular sinuses, for example, 120-130 degrees bend for accessing the maxillary sinuses, 70-90 degrees bend for accessing the frontal sinuses, and 10-15 degrees for accessing the sphenoid sinuses. The shaping tool, preferably, is designed to take account of potential recoil or spring back due to elastic deformation.

It is preferred that at the distal end of the balloon dilation device the shaft has a rounded and smoothed tip. This advantageous as tissue or other body parts of a human body are less likely to become damaged during surgery with the balloon dilation device.

Preferably, the at least one sensor coil is arranged at the shaft at the distal end or at least close to the distal end of the balloon dilation device. This is preferred since for guiding and positioning the balloon dilation device, typically, the position of the tip of the balloon dilation device has to be determined which can be achieved with high accuracy when the at least one sensor coil is arranged at the distal end of the balloon dilation device. Further, if the shaft comprises a malleable tip, the at least one sensor coil being arranged at the distal end or at least close to the distal end of the balloon dilation device is arranged at that point of the shaft that typically is bend most with respect to the rest of the shaft under an external force.

Preferably, the at least one sensor coil is connected to electrical wiring running up to the proximal end of the balloon dilation device and being configured for transmitting sensor coil signals. The electrical wiring can be connected to a cable, e.g., at an electrical connection, the cable connecting the balloon dilation device to a position detection system.

With one sensor coil, typically, five degrees of freedom can be detected, namely, three translations and two rotations. Based on the detected translations and rotations, position and orientation of the sensor coil can be determined. However, the rotation around the longitudinal axis of a sensor coil cannot not be detected. This sixths degree of freedom can be obtained, e.g., by simultaneously determining position and orientation of a second sensor coil that is arranged at a non-zero angle to the first sensor coil.

In various embodiments, it is of advantage if the balloon dilation device, additionally to the at least one sensor coil, comprises a second sensor coil that is arranged at the shaft. Preferably, the second sensor coil is displaced at a distance in longitudinal direction from the at least one sensor coil. Thus, in a situation when the first sensor coil and the second sensor coil are arranged at a non-zero angle to each other, the respective rotational degree of freedom representing rotations around a respective longitudinal axis of a respective sensor coil can be determined from the position and orientation determined for the respective other sensor coil. For example, two sensor coils can be arranged at the shaft such that after plastically shaping the shaft in its malleable tip region, the respective longitudinal axis of the two sensor coils having a non-zero angle to each other.

The second sensor coil can be displaced in longitudinal direction from the first sensor coil either more towards the tip or more towards the handle.

In various embodiments, it is preferred that the balloon is arranged between the two sensor coils. In particular, it is preferred that—if the shaft has a malleable tip region—the second sensor coil is arranged at the shaft adjacent to the malleable tip region. Thus, when bending the malleable tip region, the second sensor coil does not follow the bending but stays fixed relative to, e.g., the rest of the shaft and the handle. However, the first sensor coil that is arranged in the malleable tip region, e.g., at the distal end of the balloon dilation device, follows the bending and thus changes its angle with respect to the second sensor coil. From the determined position and orientation of the first sensor coil and from the determined position and orientation of the second sensor coil a bending of the shaft in the malleable tip region can be calculated and thus the shape of the shaft in the malleable tip region can be reconstructed and visualized on a monitor.

The balloon dilation device can have a central lumen extending from the distal end of the balloon dilation device towards the proximal end of the balloon dilation device. Preferably, the central lumen extends between the distal end and the proximal end of the balloon dilation device and has a distal opening at the distal end of the balloon dilation device and a proximal opening at the proximal end of the balloon dilation device. In other words, the central lumen, preferably, extends from an opening in the shaft at the distal end of the balloon dilation device to an opening in the handle at the proximal end of the balloon dilation device. At the opening at the proximal end of the balloon dilation device an attachment can be provided, e.g., at the handle for inserting, e.g., a marker carrier equipped with a sensor coil and/or fluoroscopically detectable markers, a light fibre or a suction tube into the central lumen.

Preferably, the central lumen has a diameter between 0.5 mm and 1.0 mm. It can be advantageous if the central lumen has a diameter that is between 0.6 mm and 1.0 mm. In various embodiments it is beneficial if the central lumen has a diameter that is between 0.7 mm and 1.0 mm. The diameter of the central lumen likewise constitutes an inner diameter of the shaft or—if the shaft comprises a hypo tube—an inner diameter of the hypo tube.

The central lumen can be used for various purposes. For example, advantageously a marker carrier can be removably arranged in the central lumen. A marker carrier comprises at least one sensor coil and can thus be used to connect a balloon dilation device to a position detection system. A balloon dilation device whose position and orientation could not be determined with a position detection system before can then be used with a position detection system. A surgeon using the balloon dilation device with a marker carrier can be supported by a position detection system in guiding the balloon dilation device to a cavity inside a human body. After positioning the balloon dilation device in, e.g., a sinus cavity, the marker carrier can be removed and the central lumen can be used for other purposes. A passable lumen can, e.g., be used for suction and irrigation purposes, i.e., for inserting a fluid, e.g. medication, into or removing a fluid from a sinus cavity.

In particular, if the balloon dilation device comprises a central lumen it is preferred that the balloon dilation device comprises a marker carrier that is removably arranged inside and extends along the length of the central lumen. It is further preferred that the marker carrier comprises the at least one sensor coil. When the balloon dilation device is position inside a sinus cavity, the at least one sensor coil sometimes is not needed anymore and can be removed as part of the marker carrier from the central lumen as not to require space in the balloon dilation device. A balloon dilation device with marker carrier can be delivered in calibrated state such that it can be directly used within a position detection system. Calibrating the at least one sensor coil to the distal tip of the balloon dilation device before surgery then is not necessary. For example, calibration data can be fed into and used by a position detection system for determining position and orientation of the balloon dilation device in relation to the position detection system.

For example, a marker carrier that is arranged in the central lumen can be a marker carrier that has a proximal end and a distal end, the marker carrier comprising at least one sensor coil that is configured for capturing an alternating electromagnetic field. Position and orientation of the at least one sensor coil can be determined with a position detection system. The at least one sensor coil is arranged at the distal end of the marker carrier or at least close to the distal end of the marker carrier. Advantageously, the at least one sensor coil is then likewise arranged at the or at least close to the distal end of the balloon dilation device having the marker carrier arranged in its central lumen. Preferably, a distal end region of the marker carrier extends from the distal end of the marker carrier to the proximal end of the at least one sensor coil such that the at least one sensor coil is arranged within the distal end region of the marker carrier. The distal end region of the marker carrier can have the same length as a malleable tip region of the shaft of the balloon dilation device. The distal end region of the marker carrier can also have a smaller length than a malleable tip region of the shaft of the balloon dilation device such that the distal end region of the marker carrier lies within the malleable tip region of the shaft.

Preferably, in the distal end region in which the at least one sensor coil is arranged, the marker carrier has at least in one section a bending stiffness of less than 10 Nmm2.

It is also preferred that the at least one sensor coil of the marker carrier is connected to electrical wiring running up to the proximal end of the marker carrier for transmitting sensor coil signals.

The electrical wiring can be connected to an electrical connection located at the proximal end of the marker carrier, the electrical connection serving for connecting the marker carrier to a cable of a position detection system.

Preferably, the at least one sensor coil of the marker carrier has a length that is at least ten times greater than the diameter of the sensor coil. Preferably, the at least one sensor coil has an induction that is between 2 mH and 4 mH.

A marker carrier is an auxiliary device that can be removably arranged in the central lumen of the balloon dilation device for using the balloon dilation device together with a position detection system. Due the marker carrier that is arranged in the central lumen of the balloon dilation device, position and orientation of the balloon dilation device can be determined with a position detection system.

Preferably, the balloon of the balloon dilation device has a length of between 10 mm and 25 mm. It can be advantageous if the balloon has a length that is between 15 mm and 20 mm. In various embodiments a length of 18 mm is preferred.

The balloon can be made, e.g., of polyester or nylon or polyurethanes. For certain applications it is of advantage if the balloon is made of polyurethane or silicone.

Preferably, —when inflated—the balloon has a maximum diameter that is between 3 mm and 10 mm, preferably between 5 mm and 8 mm, even more preferably of 6 mm. It is also preferred that the balloon is configured for holding an inflation pressure of up to 12 atm.

In particular, in various embodiments it is preferred if the balloon is configured for withstanding bending multiple times at angles of up to 120 degrees. This is of particular importance if the balloon is arranged in the malleable tip region of the shaft and thus is exposed to bending of the shaft under an external force.

The balloon dilation device can advantageously be used in balloon sinuplasty. Thus, the balloon dilation device according to the invention can be used for the treatment of blocked sinuses by inflating the balloon inside the human body. Since the balloon dilation device is equipped with at least one sensor coil, position and orientation of the balloon dilation device can be determined with an electromagnetic position detection system while a surgeon guides and positions the balloon dilation device inside a human body. Advantageously, the position of the balloon dilation device can be displayed in sectional images, e.g., of a 3D model, of a patient to assist a surgeon in guiding and positioning the balloon dilation device inside a patient's body.

With regard to the medical system, the aforementioned object is achieved by a medical system comprising a balloon dilation device, a position detection system, a fluid source and a visualization unit comprising a monitor. The balloon dilation device has an inflatable balloon and at least one sensor coil. The position detection system is configured for determining position and orientation of the balloon dilation device based on sensor coil signals provided by the at least one sensor coil of the balloon dilation device. The fluid source is attached to the balloon dilation device for feeding a fluid into the balloon. The visualization unit is configured for visualizing at least a part of the balloon dilation device on a monitor based on the determined position and orientation of the balloon dilation device.

Preferably, the balloon dilation device of the medical system is configured according to one of the embodiments of the balloon dilation device according to the invention as described before.

In particular, it is preferred if the visualization unit is configured for visualizing at least a part of the balloon dilation device on a monitor together with a preoperatively obtained model or images of a body part of a patient. Visualizing at least a part of the balloon dilation device refers to visualizing a digital representation of a part of the balloon dilation device, e.g., the balloon dilation device tip, that can also be visualized as an icon.

The medical system can comprise a device shape reconstruction unit. The device shape reconstruction unit is configured for reconstructing the shape of the balloon dilation device based on position and orientation of the balloon dilation device as determined by the position detection system. The visualization unit, preferably, is configured for visualizing the balloon dilation device in its reconstructed shape. Preferably, the device shape reconstruction unit is configured for reconstructing the shape of the balloon dilation device based on position and orientation determined for at least two sensor coils that are arranged at a relative distance from each other along the shaft of the balloon dilation device. In particular, based on position and orientation determined for at least two sensor coils, the shape of the part of balloon dilation device that lies between the two sensor coils can be reconstructed. If further sensor coils, e.g. a third and a fourth sensor coil are arranged at the shaft it is possible that the accuracy of reconstructing the shape can be improved, e.g., comparable to a spline interpolation. In particular, if the shaft comprises a malleable tip region it is preferred that at least one coil is arranged at the tip, thus, at the distal end of the balloon dilation device. At least a second sensor coil, preferably, is arranged adjacent to the malleable tip region. Under an external force, e.g., exerted by a shaping tool, the malleable tip region is bend such that the first sensor coil is displaced with respect to the second sensor coil. The displacement of the first sensor coil with respect to the second sensor coil yields that the first sensor coil is positioned at a non-zero angle to the second sensor coil with respect to their respective longitudinal axis such that a degree of bending of the part of the shaft that lies between these two sensor coils can be determined and the shape of the shaft in the malleable tip region reconstructed. The determined degree of bending can be used to visualize a digital representation of the balloon dilation device on a monitor taking into account the bending of the shaft as reconstructed with the device shape reconstruction unit.

It is advantage, if the fluid source comprises at least one fluid sensor for measuring a physical quantity of a fluid that is provided by the fluid source for inflating or deflating the balloon. Preferably, the at least one fluid sensor is configured for providing fluid sensor signals representing the measured a physical quantity. In particular, if the fluid source comprises at least one fluid sensor, the medical system, preferably, comprises a balloon shape computation unit.

The balloon shape computation unit is configured for computing the shape of the balloon based on fluid sensor signals provided by the at least one fluid sensor of the fluid source. The fluid sensor can be an inflation pressure sensor for measuring an inflation pressure. The fluid sensor can also be a fluid volume sensor for measuring an amount of fluid that has been fed into the balloon. From the measured inflation pressure and/or the amount of fluid that has been fed into or out of the balloon, the shape of the balloon can be calculated by means of the balloon shape computation unit, in particular, when further taking into account the constraints of the balloon geometry.

In particular, if the medical system comprises a balloon shape computation unit it is preferred that the visualization unit is configured for visualizing the balloon dilation device having a balloon shape as computed by the balloon shape computation unit. Thus, the balloon dilation device can be visualized with a balloon in its inflated or deflated state as computed by the balloon shape computation unit.

Regarding the method, the aforementioned object is achieved by a method for determining position and orientation of a balloon dilation device.

The method comprises the steps of

generating an electromagnetic field,

exposing the balloon dilation device to the electromagnetic field, the balloon dilation device having an inflatable balloon and at least one sensor coil,

detecting position and orientation of the at least one sensor coil,

determining position and orientation of the balloon dilation device based on the detected position and orientation of the at least one sensor coil, and

visualizing at least a part of the balloon dilation device on a monitor based on the determined position and orientation of the balloon dilation device.

Preferably, a digital representation of at least a part of the balloon dilation device, e.g., the device tip, is visualized on a monitor together with images of a patient, e.g., sectional images obtained preoperatively or intraoperatively by tomography. This allows a surgeon to guide the balloon dilation device inside a human body while orienting oneself on the displayed position of the balloon dilation device in respective images of a patient.

Preferably, the method comprises at least one of the steps of

calculating future position and orientation of the balloon dilation device with an inflated balloon based on the determined position and orientation of the balloon dilation device with a deflated balloon, or

calculating future position and orientation of the balloon dilation device with a deflated balloon based on the determined position and orientation of the balloon dilation device with an inflated balloon.

The determined position and orientation of the balloon dilation device with inflated or deflated balloon can be used to calculate a future position of the balloon dilation device. The calculated future position of the balloon dilation device can be used to visualize the balloon dilation device in a possible future state, e.g., located at a possible future position inside a cavity. Thereby, a surgeon is able to see in advance the outcome of inflating or deflating the balloon of the balloon dilation device at a certain position of the balloon dilation device, e.g., inside a cavity. Additionally, a measured inflation pressure and/or an amount of fluid fed into the balloon as well as the balloon geometry can be taken into account for calculating future positions of the balloon dilation device. A surgeon can thus estimate the consequence of inflating or deflating the balloon at a certain of the balloon dilation device inside, e.g., a sinus cavity. If a surgeon is not convinced of the possible future result, the surgeon can amend the actual position of the balloon dilation device such that a further future position of the balloon dilation device can be calculated starting from this amended actual position of the balloon dilation device.

Additionally or alternatively to the step of calculating possible future positions of the balloon dilation device, the method according to the invention can comprise the step of

determining a shape of at least a part of the balloon dilation device based on detected position and orientation of the at least one sensor coil and on detected position and orientation of a second sensor coil that are arranged at a shaft of the balloon dilation device.

Preferably, position and orientation of the first and second sensor coils are determined simultaneously.

Preferably, the second sensor coil is displaced at a distance in longitudinal direction from the at least one sensor coil. It is particularly preferred that if the balloon dilation device comprises a malleable tip region, the at least one sensor coil is arranged at the distal end of the balloon dilation device. When the shaft is bend in the malleable tip region, e.g., using a shaping tool, preferably, the at least one sensor coil arranged in the malleable tip region is displaced with respect to the rest of the shaft. For determining a shape of at least a part of the balloon dilation device and, in particular, of the shaft in the malleable tip region it is therefore preferred that the second sensor coil is arranged at the shaft outside the malleable tip region, preferably, adjacent to the malleable tip region such that the first sensor coil is also displaced with respect to the second sensor coil. The second sensor coil then represents position and orientation of the rest of the shaft that stays unbend and provides a reference for determining the bending of the shaft in its malleable tip region.

Thus, at the time of determining position and orientation of the first and second sensor coils the two sensor coils are arranged at an angle with respect to each other. From position and orientation of the two sensor coils that with the shaft being bend in the malleable tip region are displaced at an angle to each other, the shape of the balloon dilation device with bended shaft can be determined. Preferably, the method then comprises the step of

visualizing the balloon dilation device in a shape as determined based on position and orientation of the at least one sensor coil and of the second sensor coil.

Advantageously, this allows a surgeon to see the actual shape of the balloon dilation device having a bend shaft and adapt the use of the balloon dilation device accordingly. If the surgeon can see the balloon dilation device in its actual shape on a monitor, the surgeon can decide more reliably whether or not the actual position in a cavity or passageway is suitable for inflating the balloon.

Optionally, the method can comprise the step of

visualizing the shape of the balloon based on an applied inflation pressure and/or based on the amount of fluid that has been fed into the balloon.

A surgeon can thus see the balloon dilation device with inflated balloon in images of a patient. It is also possible to follow the inflation state on a monitor while increasing the inflation pressure and/or the amount of fluid feed into the balloon. Preferably, the 3D shape of balloon is visualized in the 3D model of patient. A 3D model can be generated, e.g., by overlying multiple 2D computer tomography (CT) orthogonal views of a patient.

The method can comprise the step of

visualizing a preview of the inflated balloon before actually inflating the balloon based on the determined position and orientation of the balloon dilation device.

A preview of the expanded balloon can be visualized before dilation. Advantageously, a surgeon can estimate whether inflation of the balloon yields the desired effect and if not, change the position of the balloon dilation device.

The balloon dilation device can be used in balloon sinuplasty.

The balloon dilation device can be used for dilating a Eustachian tube.

DETAILED DESCRIPTION

FIG.1schematically shows a balloon dilation device100having a balloon102and a sensor coil (not shown) arranged at the distal end106of the balloon dilation device100.

The balloon dilation device100can be used for dilating a sinus cavity and a Eustachian tube.

The balloon dilation device100comprises a shaft108, the shaft108comprising a hypo tube110. The hypo tube110can be made of, e.g., polytetrafluoroethylene (PTFE), steel, or nitinol. The hypo tube110has an outer diameter of 1.4 mm. In various other embodiments that are not shown the balloon dilation device is realised with a hypo tube having an outer diameter of between 1.2 mm and 1.5 mm. The hypo tube110has a central lumen (not visible) having a diameter of 0.8 mm thus constituting an inner diameter of the hypo tube. In various other embodiments that are not shown the balloon dilation device is realised with a hypo tube having an inner diameter of between 0.7 mm and 1.0 mm. Alternatively, the shaft can be realized without a central lumen and with the at least one sensor coil, e.g., being embedded into or attached to the shaft, preferably, at or close to the distal end of the balloon dilation device. Alternatively, the shaft of the balloon dilation device100can be configured the same way as the shafts being described with respect toFIGS.6,7,8, and9, thus, having an inner and an outer hypo tube.

The hypo tube110is attached to a handle112, the handle extending from the proximal end114of the balloon dilation device100towards the distal end106of the balloon dilation device100. The central lumen extends through the handle112to an attachment116for inserting, e.g., a marker carrier (equipped with one or more sensor coils), a light fibre or a suction tube. The handle112has a length L1of 130 mm and a diameter D1of 19 mm.

The handle112comprises an attachment118for attaching a fluid source (not shown) to the balloon dilation device, e.g., via a tube. From the attachment118, an inflation lumen (not visible) extends through the handle112and the shaft108to a connecting point (not visible) for feeding a fluid into or out of a balloon102that is arranged adjacent to the distal end106of the balloon dilation device100. The balloon102can be inflated by feeding a fluid through the inflation lumen into the balloon102. Respectively, the balloon102can be deflated by feeding a fluid out of the balloon102through the inflation lumen.

When being inflated, the balloon has a diameter D2of 6 mm. In other embodiments that are not shown the diameter of the balloon in its inflated state can be different, e.g., the diameter can lie between 3 mm and 10 mm. The balloon102is fixedly arranged at the shaft108and has a length L2of 18 mm. In various embodiments, however, the balloon can have a different length that, e.g., is between 10 mm and 25 mm, preferably, between 15 mm and 20 mm.

The shaft108has a length L3of 128 mm. Extending from the distal end106of the balloon dilation device100towards the proximal end114of the balloon dilation device100, the shaft108comprises a malleable tip region122having a length L4of 30 mm. Preferably, the malleable tip region122of the shaft108is produced by heat treatment of the shaft108.

A balloon dilation device having a shaft with a length of 128 mm can also have a malleable tip region having different length, e.g., a length that is between 10 mm and 60 mm, preferably between 20 mm and 50 mm, even more preferably between 25 mm and 35 mm. The balloon dilation device can also have a shaft having a different length, e.g., a length of between 1.2 mm and 1.8 mm, preferably between 1.2 mm and 1.6 mm, even more preferably between 1.2 mm and 1.4 mm. A balloon dilation device having a shaft with a length of between 1.2 mm and 1.8 mm can also have a malleable tip region extending from the distal end of the balloon dilation device towards the proximal end of the balloon dilation device, the malleable tip region having a length that is between 10 mm and 60 mm.

Since the balloon dilation device100is equipped with the sensor coil, position and orientation of the balloon dilation device100can be determined with a position detection system (not shown). In particular, position and orientation of the balloon dilation device100can be calculated using a determined position and orientation of the sensor coil. Therefore, the balloon dilation device100is exposed to an alternating electromagnetic field such that a current is induced in the sensor coil. The current induced depends on position and orientation of the sensor coil in relation to the alternating electromagnetic field. When a current is induced, a sensor coil signal is transmitted from the sensor coil to the position detection system, e.g., via a cable connecting the sensor coil to the position detection system. The sensor coil signal can be processed by the position detection system to determine position and orientation of the sensor coil. Having calculated position and orientation of the balloon dilation device based on the determined position and orientation of the sensor coil, the position of the balloon dilation device can be displayed in images of a patient for supporting a surgeon in navigating the balloon dilation device inside a human body.

FIG.2schematically shows a balloon dilation device200in a longitudinal sectional view with a marker carrier202, the marker carrier202comprising two sensor coils204,206that are displaced in longitudinal direction along the shaft208.

The marker carrier202is arranged in a central lumen210, the central lumen210extending from the distal end212of the balloon dilation device200to the proximal end214of the balloon dilation device200. The marker carrier202extends through the full length of the central lumen210and can be removed from the lumen through an opening216at the proximal end214of the balloon dilation device200, e.g., after having positioned the balloon dilation device200, e.g., in a sinus cavity. Because the central lumen210also has an opening218at the distal end of the balloon dilation device200, after removing the marker carrier202the central lumen210can be used for suction or irrigation purposes. For example, after removing the marker carrier202from the central lumen a suction tube can be inserted into the central lumen210for drainage of mucus from the paranasal sinuses. The central lumen210extends through the shaft208and through the handle220from the distal end212of the balloon dilation device200to the proximal end214of the balloon dilation device200. By way of example, the shaft can comprise one hypo tube as described with reference toFIG.1or can have an inner and an outer hypo tube as described with reference toFIG.5,6,7,8, or9.

Furthermore, an inflation lumen (not shown) extends from the proximal end214of the balloon dilation device200to a connecting point (not shown). At the connecting point the inflation lumen is fluidly connected to a balloon222that is arranged at the shaft208. Through the inflation lumen a fluid can be fed into or out of the balloon for inflating and deflating the balloon222, respectively.

The balloon222is arranged within a malleable tip region224of the shaft208. In the malleable tip region, the shaft can be plastically deformed to facilitate accessing passageways and positioning of the balloon dilation device200, e.g., in sinus cavities.

The first sensor coil204is arranged at the distal end212of the balloon dilation device200such that when the shaft is plastically deformed in the malleable tip region224, e.g., using a shaping tool, the sensor coil204is displaced with respect to the rest of the shaft.

The second sensor coil206is arranged at the shaft but adjacent to the malleable tip region224. Hence, if the shaft208is bend in the malleable tip region224, the second sensor coil206is not displaced with respect to the rest of the shaft208. Position and orientation of the second sensor coil thus represent position and orientation of the part of the shaft that stays unbend. However, when plastically deforming the shaft in the malleable tip region224, the first204sensor coil is displaced with respect to the second sensor coil206such that the two sensor coils204,206have a non-zero angle enclosed between their longitudinal axis.

By determining position and orientation of the first and second sensor coils204,206, the degree of bending of the shaft208can be calculated from the determined position and orientation of each of the two sensor coils204,206. In particular, the shape of the balloon dilation device in that section of the shaft that lies between the two sensor coils204,206can be reconstructed based on the determined position and orientation of each of the two sensor coils204,206. Using the reconstructed shape of the balloon dilation device, the balloon dilation device200can be visualized on monitor in its actual shape thus having a bend malleable tip region224.

This is of advantage since a surgeon can decide more reliably when to inflate or deflate the balloon222inside a sinus cavity based on the actual position and shape of the balloon dilation device200positioned inside, e.g., a sinus cavity.

FIG.3schematically shows a medical system300comprising a balloon dilation device302, the balloon dilation device302comprising a sensor coil304and a balloon306.

The balloon dilation device302can be configured the same way as the balloon dilation device described with reference toFIG.1or the balloon dilation device described with reference toFIG.2or the balloon dilation device as described with reference toFIG.5.

The balloon dilation device302is connected to a fluid source308via a tube. The fluid source is configured for providing a fluid, i.e., a gas or a liquid. For inflating the balloon306, a fluid is fed into the balloon306. The fluid source308comprises an optional fluid sensor310for measuring a physical quantity of a fluid that is fed into the balloon. The fluid sensor can be an inflation pressure sensor for measuring an inflation pressure or a fluid volume sensor for measuring an amount of fluid that has been fed into or out of the balloon. Also both sensors can be present at the same time. Additionally or alternatively to one or more fluid sensors comprised by the fluid source, the balloon dilation device itself can have one or more fluid sensors. These fluid sensor of the balloon dilation device can likewise be an inflation pressure sensor or a fluid volume sensor. The balloon dilation device can also comprise a sensor that is configured for directly detecting the shape of the balloon. Fluid sensor310of the fluid source308and, if present, fluid sensors comprised by the balloon dilation device302itself are configured for providing fluid sensor signals representing the measured a physical quantity of the fluid.

Fluid sensor signals representing a measured physical quantity of the fluid can be transmitted to a balloon shape computation unit312, e.g., via a cable or wireless. The balloon shape computation unit312is configured for computing the shape of the balloon306based on fluid sensor signals provided by the fluid sensor310of the fluid source308. If no fluid sensor310for measuring a physical quantity of the fluid is present in the medical system300, also no balloon shape computation unit312needs to be present which is thus an optional element.

The balloon shape computation unit312is connected to a visualization unit314, the visualization unit314, preferably, being configured to access and use the computed balloon shape. Thus, the visualization unit314is configured to process the computed balloon shape, in particular, for visualizing the balloon dilation device302having a balloon shape as computed by the balloon shape computation unit308on a monitor316.

The medical system300comprises a position detection system318for determining position and orientation of the balloon dilation device302based on sensor coil signals provided by the sensor coil304Preferably, the sensor coil304is arranged at the shaft of the balloon dilation device302at the distal end of the balloon dilation device302. The position detection system318can comprise a field generator (not shown) for generating an alternating electromagnetic field. For determining position and orientation of the balloon dilation device302, the balloon dilation device302equipped with the sensor coil304is exposed to the alternating electromagnetic field such that a current is induced in the sensor coil304. When a current is induced, respective a sensor coil signal can be transmitted to the position detection system318, e.g., via a cable or wirelessly. The position detection system318is configured for processing a received sensor coil signal for calculating position and orientation of the balloon dilation device302. This often includes that position and orientation represented by the sensor coil signal are determined and used together with transformation functions obtained by calibrating the sensor coil to the tip of the balloon dilation device302to calculate position and orientation of the balloon dilation device302relative to the position detections system318.

The position detection system318is connected to the visualization unit314. The visualization unit314is configured for visualizing a digital representation of at least a part of the balloon dilation device302, e.g., the balloon dilation device tip, on the monitor316based on the position and orientation of the balloon dilation device302as determined by the position detection system318. Preferably, a digital representation of the balloon dilation device302is visualized together with images of a patient to support a surgeon in handling the balloon dilation device302while guiding the balloon dilation device302inside the human body.

In particular, if the balloon dilation device302comprises several sensor coils, preferably, at least two sensor coils, arranged at and distributed along the length of the shaft of the balloon dilation device302, the medical system can comprise an optional device shape reconstruction unit320. The device shape reconstruction unit320is connected to the position detection system318and to the visualization unit314. The device shape reconstruction unit320is configured for reconstructing the shape of the balloon dilation device302based on position and orientation of the sensor coil304determined by the position detection system318. In particular, the device shape reconstruction unit320is configured for accessing the determined position and orientation for each sensor coil present in the balloon dilation device302and to process the determined positions and orientations of the sensor coils for reconstructing the shape of the balloon dilation device302.

Preferably, if a device shape reconstruction unit320is present, the visualization unit314is configured for visualizing the balloon dilation device302in its reconstructed shape. In particular, the shape of the balloon dilation device can be reconstructed taking into account a possible bending of the shaft in its malleable tip region.

FIG.4shows a flow diagram representing a method for determining position and orientation of a balloon dilation device. The method described in the following can be implemented using a medical system as described with reference toFIG.3.

The method comprises the steps of

generating an electromagnetic field S1,

exposing the balloon dilation device to the electromagnetic field, the balloon dilation device having an inflatable balloon and at least one sensor coil S2,

detecting position and orientation of the at least one sensor coil S3,

determining position and orientation of the balloon dilation device based on the detected position and orientation of the at least one sensor coil S4, and

visualizing a digital representation of at least a part of the balloon dilation device on a monitor based on the determined position and orientation of the balloon dilation device S5.

FIG.5shows a balloon dilation device500comprising a balloon502, a shaft504, a handle506and at least one sensor coil (not shown).

The shaft504extends from the distal end508of the balloon dilation device500towards the proximal end510of the balloon dilation device500and has an inflation lumen (not visible). The shaft504comprises an inner hypo tube512and an outer hypo tube514. The inner hypo tube512has an outer diameter that is equal to or smaller than the diameter of a lumen of the outer hypo tube514. The inner hypo tube512is at least partly arranged inside the lumen of the outer hypo tube514. At least with the outer hypo tube514, the shaft504is attached to the handle506. The outer hypo tube514does not extend up to the distal end508of the balloon dilation device500but ends before. The inner hypo tube512extends up to the distal end508of the balloon dilation device500. The total length of the shaft504thus is the sum of the lengths of the visible part of the outer hypo tube514and the visible part of the inner hypo tube512.

The inner hypo tube512is completely annealed such that it has an ultimate tensile strength of up to 750 N/mm2. That part of the inner hypo tube512that extends between the distal end508of the balloon dilation device500and the distal end of the outer hypo tube514, i.e., the visible part of the inner hypo tube512, forms a malleable tip region516of the shaft.

In the malleable tip region516the inflatable balloon502is fixedly arranged at the shaft504, i.e., attached to the inner hypo tube512of the shaft504. The balloon502has a length that is approximately equal to the length of the malleable tip region516. Thereby, when plastically deforming the shaft504in the malleable the region516, the balloon502itself also deforms accordingly. In particular, if the malleable tip region516is formed to have an angle, typically, the balloon502, too, shows a corresponding bend.

The balloon502is fluidly connected to the inflation lumen of the balloon dilation device500such that the balloon502can be inflated and deflated by feeding a fluid through the inflation lumen into or out of the balloon502. The fluid for inflating the balloon502can be provided by a fluid source (not shown) that is connect to the inflation lumen, e.g., via a tube, at the attachment518arranged at the handle506. The inflation lumen thus extends from the attachment518through the handle506and the shaft504to a connecting point (not visible) for feeding a fluid into or out of a balloon502.

The balloon dilation device500comprises a central lumen (not visible). The central lumen extends from an opening of the inner hypo tube512at the distal end508of the balloon dilation device500to an attachment520that is arranged at the handle506. Alternatively, the central lumen can extend from the attachment520through the handle506and the shaft and end before the distal end508of the balloon dilation device500. In that embodiment the shaft can be closed at the distal end508of the balloon dilation device500, i.e., in this case no opening is present at the distal end508of the balloon dilation device500.

In the central lumen at least one sensor coil (not shown) is arranged that is configured for capturing an electromagnetic field and for providing a sensor coil signal representing position and orientation of the sensor coil. By means of the at least one sensor coil, the balloon dilation device500can be connected to a position detection system that is configured for determining position and orientation of the balloon dilation device500in an electromagnetic field.

The at least one sensor coil can also be comprised in a marker carrier that is arranged inside the central lumen of the balloon dilation device500. In particular, through the attachment520, a marker carrier comprising, e.g., two sensor coils can be inserted into the central lumen to be removably arranged inside the central lumen.

If a marker carrier comprises at least one sensor coil that is configured for capturing an electromagnetic field, position and orientation of the sensor coil can be determined with an electromagnetic position detection system. In particular, the at least one sensor coil of a marker carrier can be used to connect the balloon dilation device500to a position detection system in order to track the position of the balloon dilation device500. By connecting the balloon dilation device500to a position detection system, it is possible to display the position of the balloon dilation device500in sectional images of a model of a patient in order to assist a surgeon in navigating the balloon dilation device500. Since the marker carrier can be arranged removably inside the central lumen, after having positioned the balloon dilation device500in a cavity, the marker carrier can be removed from the central lumen and, e g., a suction tube can be inserted into the central lumen.

If a marker carrier comprising sensor coils is arranged inside the central lumen, preferably, one sensor coil is arranged at the distal end508of the at least balloon dilation device500and a second coil is arranged adjacent to the malleable tip region516, i.e., in that part of the shaft504in which the outer hypo tube514is present. Preferably, the sensor coils of the marker carrier are arranged inside the central lumen such that, if the malleable tip region of the shaft is deformed plastically, a non-zero angle is enclosed between the longitudinal axis of the two coils. From the determined position and orientation of the two sensor coils with respect to each other, it is possible to determine a bending of the shaft504, in particular, in the malleable tip region516and to reconstruct the shape of the balloon dilation device500having a shaft with a plastically deformed malleable tip region.

FIG.6shows a shaft600that has an inner hypo tube602and an outer hypo tube504. The shaft600can be attached to a handle (not shown) of a balloon dilation device, e.g., of a balloon dilation device as described with respect toFIG.1or of a balloon dilation device as described with respect toFIG.5.

The inner hypo tube602is completely annealed. The outer hypo tube604is configured such that it does not plastically deform if an external force of a magnitude typically acting on the shaft during surgery is exerted on the outer hypo tube604. The inner hypo tube602is at least partly arranged inside a lumen of the outer hypo tube604.

The outer hypo tube604ends before the distal end606of the shaft600. The inner hypo tube602extends up to the distal end606of the shaft600such that the shaft's total length is the sum of the visible parts of the inner hypo tube602and the outer hypo tube604.

That part of the inner hypo tube602that extends from the distal end of the outer hypo tube604to the distal end606of the shaft600forms a malleable tip region608of the shaft600. In particular, in the malleable tip region608, the shaft can be plastically deformed, e.g., using a shaping tool. It is preferred that prior surgery, the shaft in its malleable tip region608is plastically deformed so that the shape of the shaft is suitable for a specific procedure to be carried out with a balloon dilation device.

For example, for different procedures in the malleable tip region608the shaft600can be plastically deformed to have a specifically selected angle with respect to the rest of the shaft, i.e., with respect to the outer hypo tube604. For example, a shaping tool can be used having several pre-fixed shape positions that are suitable, e.g., for accessing a particular cavity.

Fixed to the shaft600in the malleable tip region608there is an inflatable balloon610. The balloon610has a length that corresponds to the length of the malleable tip region608. The balloon610is fluidly connected to the inflation lumen (not visible) of the shaft600such that the balloon610can be inflated and deflated by feeding a fluid through the inflation lumen into or out of the balloon600.

At the shaft600, at least one sensor coil (not visible) is arranged, the at least one sensor coil being configured for capturing an electromagnetic field and for providing a sensor coil signal representing position and orientation of the sensor coil in an electromagnetic field. For example, the shaft600can comprise two sensor coils that are arranged at the shaft600as described with reference toFIG.7.

InFIG.7, a shaft700is shown in a longitudinal sectional view, the shaft700having an inner hypo tube702and an outer hypo tube704that are arranged and configured as described with reference toFIG.6. Also as described with reference toFIG.6there is a balloon706fixedly arranged at the shaft700.

The shaft700has a central lumen708and an inflation lumen (not visible). In the central lumen708two sensor coils710,712are arranged. The first sensor coil710is arranged at the distal end714of the shaft700and the second sensor coil712is arranged adjacent to the malleable tip region716of the shaft700. If the malleable tip region716is plastically deformed to have an angle with respect to the rest of the shaft700, preferably, the two sensor coils are displaced such that their longitudinal axis enclose a non-zero angle.

Each of the sensor coils710,712is connected to electrical wiring (not shown) running from the respective sensor coil710,712towards a proximal end of the shaft700. Preferably, if the shaft700is attached to a handle of a balloon dilation device, the electrical wiring run up to an electrical connection of the balloon dilation device at which the electrical wiring can be connected to a cable for connecting the balloon dilation device to a position detection system. Via the electrical wiring, sensor coil signals provided by the sensor coils710,712can be transmitted to a position detection system that is configured for determining position and orientation of each of the sensor coils710,712by analysing respective sensor coil signals. Based on determined position and orientation of the two sensor coils it is possible to determine the bending of the shaft700and to reconstruct the actual shape of the shaft700in case the malleable tip region716of the shaft700is plastically shaped.

The sensor coils710,712can be part of a marker carrier that is removably arranged inside the central lumen708of the shaft700to connect a balloon dilation device to a position detection system.

It is also possible that the shaft comprises only one of the sensor coils710,712or additional sensor coils that are distributed along the length of the shaft.

InFIG.8, a shaft800is shown having a completely annealed inner hypo tube802and an outer hypo tube804. The outer hypo tube804is configured such that it does not plastically deform if an external force of a magnitude typically acting on the shaft800during surgery is exerted on the outer hypo tube804. The shaft800can be attached to a handle (not shown) of a balloon dilation device, e.g., of a balloon dilation device as described with reference toFIG.1or of a balloon dilation device as described with reference toFIG.5.

The inner hypo tube802is arranged at least partly in a lumen of the outer hypo tube804. The outer hypo tube804ends before the distal end806of the shaft800. The completely annealed inner hypo tube802extends up to the distal end806of the shaft800and that part of the inner hypo tube802that extends from the distal end of the outer hypo tube804to the distal end806of the shaft800forms the malleable tip region808of the shaft800.

In the malleable tip region808, a balloon810is fixedly arranged at the shaft800. The balloon810is fluidly connected to the inflation lumen (not visible) of the shaft800such that the balloon810can be inflated and deflated by feeding a fluid through the inflation lumen into or out of the balloon800.

The balloon810is arranged adjacent to the distal end806of the shaft and has a length that is smaller than the length of the malleable tip region. As a result, the proximal end of the balloon810ends before proximal end of the malleable tip region808such that there is an exposed section812of the inner hypo tube802in which no balloon810is arranged. Preferably, this exposed section812of the inner hypo tube802forms a bending section in which the malleable tip region808can be plastically deformed several times for shaping the malleable tip region808.

If the malleable tip region808is deformed in the exposed section812such that the malleable tip region808has an angle to the rest of the shaft800, i.e., to the outer hypo tube804, the remaining part of the malleable tip region808in which the balloon810is arranged can maintain its shape. Advantageously, thereby, the balloon810itself is not mechanically stressed by shaping the malleable tip region808and can maintain its balloon shape.

At the shaft800, at least one sensor coil (not visible) is arranged. For example, the shaft800can comprise two sensor coils that are arranged at the shaft800as described with reference toFIG.9.

FIG.9shows a shaft900in a longitudinal sectional view, the shaft900having a completely annealed inner hypo tube902and an outer hypo tube904that are arranged and configured as described with reference toFIG.8.

The shaft900has a central lumen906and an inflation lumen (not visible). In the central lumen906two sensor coils908,910are arranged such that a first coil908is arranged at the distal end912of the shaft900and a second coil910is arranged adjacent to the malleable tip region914. The two sensor coils908,910are connected to electrical wiring (not shown) for connecting the two sensor coils908,910to a position detection system. From sensor coil signals provided by the sensor coils908,910, position and orientation of each of the sensor coils can be determined with a connected position detection system.

In the malleable tip region914, a balloon916is fixedly arranged at the shaft900and fluidly connected to the inflation lumen such that the balloon916can be inflated and deflated by feeding a fluid through the inflation lumen into or out of the balloon916.

As described with reference toFIG.8, the balloon912is arranged adjacent to the distal end912of the shaft900and ends before the distal end of the outer hypo tube904. Thereby, a section918of the inner hypo tube902that extends between the proximal end of the balloon916and the proximal end of the malleable tip region914is exposed, i.e., is visible from outside. In particular, in the exposed section918, the shaft can be plastically deformed to shape the malleable tip region914to have an angle to the rest of the shaft900.