WO2009148317A1

WO2009148317A1 - Automatic catheter positioning system

Info

Publication number: WO2009148317A1
Application number: PCT/NL2009/050314
Authority: WO
Inventors: Borut Gersak; Mauro Sette; Hugo Furtado; Nele Famaey; Thomas P. Stüdeli; Eigil Samset
Original assignee: Technische Universiteit Delft; Universitetet I Oslo; Katholieke Universiteit Leuven
Priority date: 2008-06-05
Filing date: 2009-06-05
Publication date: 2009-12-10

Abstract

A system for positioning a distal end of a catheter (1) at a predetermined location within a passage, and for maintaining said distal end at the predetermined location, the system comprising: a position sensor (2) located at or near said distal end; location determining means for determining an actual location of said distal end of said catheter within the passage based on said position sensor,- difference determining means for determining a difference between the actual determined location of said distal end of said catheter and said predetermined location; an actuator attached (13) to said catheter for moving said catheter within the passage; controlling means for controlling said actuator; wherein, if said difference determining means determines a difference between the actual determined location of said catheter and said predetermined location, said controlling means controls said actuator to move said catheter to said predetermined location.

Description

Automatic Catheter Positioning System

FIELD OF THE INVENTION

The present invention relates generally to medical de^¬ vices, and more particularly to medical devices for Minimal In^¬ vasive Cardiac Surgery (MICS) , and common interventional cardiac surgery, and more particularly to a system to visualize the position of a catheter to perform aortic clamping or administer substances for medical treatment or place a medical treatment device, and to control the position of such a catheter.

BACKGROUND OF THE INVENTION

In many types of cardiac surgery the heart has to be stopped. For the heart to be stopped the patient must be placed under Cardio Pulmonary Bypass (CPB), that is, an external machine (often called heart-lung machine) is oxigenating and pumping blood into the body.

For the patient to be under CPB and for the heart to be stopped, no blood must enter the coronary arteries. Instead of blood, the coronary arteries will be perfused with Cardioplegia, a solution which protects the myocardium. Because of this, the aorta has to be sectioned isolating the heart from the rest of the aorta. This sectioning guarantees that blood is flowing through the aorta, to the brachiocephalic branch and also through the descending aorta towards the lower part of the body but it is not entering the coronary arteries. The classic way to perform this sectioning is by means of a clamp applied directly on the aorta walls, more particularly in the aortic arch, between the aortic valve and the brachiocephalic arteries. The clamp thus isolates the two sec^¬ tions in the aorta from another. In MICS the access to the xnside of the chest is re^¬ duced. A set of incisions, often called ports are made but these are too small for the use of a conventional clamp.

One of the ways to implement aortic clamping in MICS has been disclosed in US patent no. 57661511 where a catheter having a balloon in its distal part is advanced until the place where the sectioning should be done and is then inflated. The inflated balloon provides the same kind of sectioning as the clamp and on the same location. One alternative technique for performing MICS that is used nowadays is by enlarging one incision or making an extra incision to insert the classical clamp.

The balloon catheter represents a good possibility of performing the surgery with the smallest incisions possible, but it has some drawbacks. These are mostly related with difficulties in placement and monitoring during the surgery.

As said before, the balloon should section the aorta between the aortic valve and the brachiocephalic artery. Serious complications could arise should the balloon be placed or move towards the heart or in the opposite direction. It is extremely important then, to guarantee its correct placement at all times. If the balloon is placed or moves towards the heart it might occlude the coronary arteries blocking the delivery of cardiople- gia to the myocardium thus impairing its protection while being stopped. If the balloon is placed or moves towards the other side, it might occlude the brachiocephalic artery stopping the flow of oxygenated blood to the brain through that artery. The consequences could range from none (because there is redundancy on the blood supply chain to the brain) to death (because there is no guarantee that the redundancy is not malfunctioning also) .

There are two important situations that can cause the balloon to be misplaced. The first is at the initial placement itself where difficulties in controlling its behaviour can lead to it stabilizing its position in the wrong location. The other is during the surgery. The balloon is in the correct location and by some event (pushing by the surgeon, too big difference in pressure, etc.) it migrates away from it.

As said, the first situation is at the initial balloon placement. In the beginning, the surgeon inserts the catheter through the femoral artery and pushes it forward until it reaches its intended position in the ascending aorta. Then inflation is started and the drugs to stop the heart administered. The patient is already under CPB so the machine is pumping oxy- genated blood into the descending aorta to all the body. As the heart is stopping, there is a drop of pressure upstream of the balloon because the heart is not pumping anymore. Because the balloon is inflating and the CPB machine is pumping blood downstream, there is a lot of instability due to the irregular blood flow paths. This instability causes the balloon to move irregularly, especially to be dragged with inconstant forces towards the aortic valve. This motion has to be compensated by the surgeon who has to pull the catheter with the correct force with the objective of leaving it in the correct location as soon as the instability stops (which will be the moment in which the balloon is sealing the ascending aorta) . This is a hard task and many times, when sealing starts, the balloon rests in the incorrect location. The surgeon has to rely solely on haptic feedback for control of applied forces, pushing too hard has a risk of rupturing the aorta. The second situation is balloon migration. During the surgery, the balloon catheter is in a stable situation most of the time. There is more pressure downstream as the CPB machine is pumping the blood, but the balloon is held tight, with friction with the walls of the aorta and its own wire held with a suture close to the groin. At regular intervals, cardioplegia solution has to be administered to the coronary arteries in order to maintain myocardium protection. Depending on the flow of cardioplegia, the force created by this delivery can break the equilibrium and push the balloon downstream leading to a possi- ble occlusion of the brachiocephalic artery. Also, the surgeon might unintentionally touch and push the balloon.

Similar problems occur with Balloon Valvuloplasty. Balloon valvuloplasty, also called percutaneous balloon valvuloplasty, is a surgical procedure used to open a narrowed heart valve. The procedure is sometimes referred to as balloon enlargement of a narrowed heart valve.

Balloon valvuloplasty is performed on patients who have a narrowed heart valve, a condition called stenosis. The goal of the procedure is to improve valve function and blood flow by enlarging the valve opening. It is sometimes used to avoid or delay open heart surgery and valve replacement.

A balloon valvuloplasty procedure consists of placing one or two special catheters across a narrowed heart valve. The narrowing usually occurs when parts of the valve, which are called leaflets, fuse (stick together) .

The first part of a balloon valvuloplasty or angioplasty is identical to a standard heart catheterization. Blood pressure readings are taken within the heart to determine the degree of narrowing or tightness across the valve or vessel. A deflated balloon catheter then is placed across the narrowed area. The balloon is inflated, and as it expands, it stretches open the narrowed area. The balloon then is rapidly deflated and blood pressure readings again are measured to determine the results. If necessary, the balloon procedure can be repeated to further decrease the tightness across the valve or vessel. During the procedure aortic root angiography is performed and displayed to facilitate subsequent positioning of the balloon.

During any heart catheterization, complications can result such as infection, bleeding, perforation through a blood vessel or heart wall, blood clots (which could result in a stroke), disturbances of the heart rhythm and even death. The risk of these complications occurring is greater during balloon valvuloplasty than during a standard heart catheterization and are mainly due to incorrect positioning or driving of the cathe- ter.

Percutaneous Valve Implantation

When the valve stenosis cannot be treated with valvu- loplasty, the complete replacement of the natural valve with an artificial one is necessary.

In the current state of the art the valve replacement is performed through sternotomy or minimally invasive access.

It is also possible to use a stent mounted valve, that can be implanted by means of a catheter procedure.

The deployment device is a balloon catheter on which is crimped the stent valve. For the transarterial approach, the occlusive fabric skirt must be mounted distally on the balloon catheter . A deflectable guiding catheter is used to facilitate passage of the prosthesis through the arterial system and aortic valve. Active deflection is accomplished by rotation of an external handle. The prosthesis, balloon, and deflection catheter are introduced into the femoral sheath as a unit through a haemostatic loader catheter.

During the procedure aortic root angiography is performed and displayed to facilitate subsequent positioning of the prosthesis. Balloon valvuloplasty is performed in a standard manner with a balloon slightly smaller than the diameter of the planned prosthesis. After valvuloplasty, the femoral access site is sequentially dilated to allow introduction of the large sheath to a position beyond the iliac arteries into the aorta. A steerable deflection catheter is used to actively direct the prosthesis through the tortuous aorta.

The prosthesis is positioned such that it is coaxial within the calcified native valve leaflets.

During prosthesis implantation, rapid right ventricular pacing as well as delivery of medicament, e.g. cardioplegia are used to minimize pulsatile transaortic flow which would otherwise act to eject the inflated device-deployment balloon.

When the catheter is in the correct position, the crimped valve is expanded and stabilized against the aortic wall. Then the balloon is deflated. Only when the balloon is fully deflated and the pacing is terminated the catheter system is withdrawn.

The prosthesis is positioned such that its midpoint is adjacent to fluoroscopically visible native leaflet calcification. Aortography that used hand injections through a pigtail catheter placed immediately above the valve is often helpful. The posteroanterior view is used most commonly; however, at times, other angulations are useful to visualize the valve plane. Transesophageal echocardiography is used but sometimes is limited in its ability to clearly distinguish the prosthesis while mounted on the balloon catheter. Echocardiographic visualization of the native valve leaflets is of particular value when valve calcification is mild and fluoroscopic positioning difficult .

An unsuccessfully deployed prosthetic valve can result in embolization. Potential contributors to embolization include native annulus/prosthesis mismatch, aggressive predilation of the native valve, and excessively high positioning.

Optimal positioning of the prosthetic valve is critical and embolization, paravalvular insufficiency, and coronary ob- struction are to be avoided. Dependence on fluoroscopic visualization of the native valve is problematic owing to variability in the amount and location of calcification. Aortography and transesophageal echocardiographic assessment may yet be helpful. Stent Graft

Positioning problems are also eminent when placing stents . A stent graft is a tubular device, which is composed of special fabric supported by a rigid structure, usually metal. The rigid structure is called a stent. An average stent on its own has no covering, and therefore is usually just a metal mesh. Although there are many types of stents, these stents are used mainly for vascular intervention.

The device is used primarily in endovascular surgery. Stent grafts are used to support weak points in arteries, com^¬ monly known as an aneurysm. Stent grafts are most commonly used in the repair of an abdominal aortic aneurysm, in a procedure called an EVAR. The theory behind the procedure is that once in place inside the aorta, the stent graft acts as a false lumen for blood travel through, instead of into the aneurysm sack.

The deployment device is a balloon catheter on which is crimped the stent graft. The catheter is inserted into the groin and push up into the aorta until it reaches the aneurism.

Then the balloon is inflated causing the expansion of the stent.

Once the stent is in the correct position the balloon is deflated and the catheter is withdrawn. Risks connect to this procedure are occlusion of blood vessels efferent the aorta with subsequent spinal cord ischemia. Because of the difficulties in placement and monitoring described above we propose a system aiming at making it easier for the surgical team to cope with these difficulties.

SUMMARY OF THE INVENTION

We propose a system intended to assist the surgical team during the initial placement and/or during the intervention. Embodiments of the system will preferably provide visualisation of the catheter position at all times and automatic position control in the vascular system.

Thus, embodiments of the system preferably provide a method for visualisation of the catheters position at all times. Also, embodiments of the proposed system preferably automatically control the initial placement of the catheter. Additionally, embodiments preferably to provide an automatic keep-in-place mechanism that will warn the team of any displacement of the catheter and will try to compensate for it automatically. For the visualization of the catheter's position, we propose to use the data collected in real time from a position sensor placed at the distal end of the catheter and to represent it in a 3D visualization environment, superimposed on the body structures which will be rendered from pre-operative 3D scans of the patient's thorax.

The position sensor can be magnetic but other sensors can be used.

For this we make the assumption that the patient's organs do not move significantly and that we can relate the 3D im- aging obtained pre-operatively with the organs structure and position at the time of the surgery. If this assumption proves to be wrong, a method for deformable registration can be used to represent the catheter, or at least its distal end embedded in the body structures. If the registration is correct, the catheter's position can be represented in real-time and the representation will correspond to the location of the catheter's distal part inside the patient. Like this, the team will have a visual feedback on the catheter' s position and can determine easily - when the catheter has a balloon - whether this balloon is stable or if it has moved and lodged in a different location. This system can also be used to see the catheter's progression through the vascular system during the initial placement. Said approach will increase the control of applied forces and reduce the risk of (aortic) ruptures.

A sensor should preferably also be placed in the guide wire so that it can also be visualized in the display.

For the automatic control of the positioning a feedback control loop, based on the catheter's position, can be used. The catheter' s position can also be acquired in real time when the position sensor is inside the balloon. Such a balloon can be inflated either manually or by a mechanical pump. A mechanical actuator can pull or push the catheter according to the signal generated by the feedback control loop, thus controlling its po- sition. For the keeping in place during the surgery the control principle can be the same as for the initial placement. A feedback control loop based on the position of the catheter's distal part can be used, also when the catheter is provided with a bal- loon that is inflated. Additionally, if this position needs to be changed, the system also allows for the pressure within the balloon to be reduced, manually or automatically, so that the balloon at least partially deflates, which facilitates movement of the catheter.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the invention will become more apparent hereinafter from the following de- tailed disclosure of a preferred, though not exclusive, embodiment of the invention which is illustrated, by way of indicative, but not limitative, example in the accompanied drawings, where :

Figure 1 shows the location of the prefered aorta physical sectioning.

Figure 2 shows a catheter inserted with the balloon deflated 2 and with the balloon inflated 3.

Figure 3 shows the balloon occluding coronary arteries 4 and occluding brachiocephalic artery 5. Figure 4 shows the balloon well placed and deflated.

The CPB machine is pumping and heart is pumping also. We can see an indication of the flow of blood via the arrows.

Figure 5 shows the balloon in the same position as figure 4 but it is now a bit inflated. Also the aproximate flow 6 is shown in a situation where the heart is not pumping anymore .

Figure 6 represents the delivery of cardioplegia from one of the lumens of the balloon 1.

Figure 7 shows a close view of the balloon 1 with one possibility for the position sensor 7.

Figure 8 shows in possible user interface for the visualization of the balloon. We can see two 2D views 8 and 9 and a 3D view 10. Also there are controls to select the target 11 and to start and stop the controller, 12. Figure 9 shows a possible realization of an actuator for pushing and pulling. Figure 10 is a conceptual schematic of a negative feedback control loop.

Figure 11 shows a schematic representing the information flow in the whole system. Figure 12 shows one possible physical realization of the system.

Figure 13 shows the position of the balloon and of the catheter when it is used in the procedure of balloon valvuloplasty . Figure 14 shows the position of the catheter, balloon and stent-graft when it is used in the procedure of placing a stent graft.

Figure 15 shows the position of the catheter, balloon and stent valve when it is used in the procedure of placing a percutaneous stent valve.

Figure 16 shows a possible realization of an actuator for pushing, pulling and rotating a catheter.

DESCRIPTION OF THE PREFERED EMBODIMENTS

Although the following discussion illustrates the system and its use particularly with reference to Minimally Invasive Port Access Surgery (MIPAS) it is clear for the artisan that the system and its use is not restricted thereto, and that it can be used in many other surgical procedures, some of which will also be briefly referred to (partly also with reference to the drawings) .

Two important concepts that the present invention provides the surgical team with when performing MIPAS should be noted. First, the position of the balloon is preferably known at all times inside the patient. Second, and profiting from the first one, we can have automatic position control of the endo- clamp catheter .

The surgery is preferably performed like a conventional Minimally Invasive Port Access ™ Surgery with some minor exceptions .

As in normal Minimally Invasive Heartport™ surgery, the heart-lung machine is functioning normally but the oxygenated blood input into the aorta is done by a catheter in the femoral artery and not in the aortic arch. As said before, the clamping of the Aorta is done preferably using a known device, such as the Endoaortic Port Access™ Catheter. This device has a balloon at its tip, that will be referred herein simply as the balloon. The system as seen in figure 12 preferably comprises the referred catheter 1, a position sensor 2 added to it, a piece of software 14 responsible for the managing of the tracking data and the visualization of the same data, a mechanical actuator 13 that can be controlled by software, a mechanical pump to inflate and deflate the balloon that can be controlled by software 14 and a piece of software 15 that implements the control algorithm.

The piece of software 14, which we will call manager software, is itself a system used to manage and visualise the position data and used also to interact with the user. The software is capable of receiving a data stream with data regarding the position of a sensor in 3D space that will be simply referred as tracking data. The software is also able to read 3D datasets of a patient's anatomy and display them in a 3D view or only slices of the datasets in a 2D view.

Also, the software is able, to represent a virtual object which position is locked to the position indicated by the tracking data and, to superimpose this object in the patient's dataset with the correct alignment, given that a certain mathe- matical transformation is defined.

In the software, using for instance the user interface in figure 8, the user can define a target point in space where he desires the balloon (see for instance Figs. 4, 5, 13) and/or eventually a stent or stent-valve (see Figs. 14, 15) to be placed. The software is then able to calculate the distance between the measured position of the distal end of the catheter and this target point. This distance we call position error.

Another piece of software referred as 15 in figure 12 will implement the control algorithm. This software that we will call control software implements a given control algorithm which is responsible for generating the numerical signals that will bring the balloon (with or without a stent) to the target. Both the manager software and the control software can communicate through a certain protocol to share data regarding the error in position of the balloon at the distal end of the catheter. One possible though not exclusive communication protocol is TCP/IP. By receiving the error value from the manager software, the control software can try to minimize this error. This is done by converting the numerical signals generated by the control software into electrical signals that will control the actuator 13 resulting in catheter movement. The control software can try at all times that the movement is always in the direction required to minimize the position error.

The proximal end of the catheter that is outside the patient can either be controlled by hand during one stage of the procedure or attached to the actuator so it can be driven by it, in a latter phase of the procedure.

The catheter can be inserted as usual under monitoring the position of the catheter on the user interface (if wanted) . The insertion for instance is done until a position in the aor- tic arch similar to the one shown in figure 2. At this point, the surgeon can inform the system via the user interface of figure 8 that everything is ready to be taken over automatically. A target point where the balloon (and/or the stent) is required to be is preferably defined via the user interface 11. From the point in time where the user tells the system to take over, the actuator will preferably always try to have the distal end of the catheter in the defined position.

The inflation (or deflation) of the balloon can either be done by hand as usual or can be done with a pump which is also controlled by the system. In case of manual inflation, first the user should preferably tell the system to take over and then start inflation. In case of automatic inflation, the system controls the inflation by means of a mechanical pump and a pressure sensor. The pressure sensor measures the pressure in- side the balloon. An electrical signal generated by a pressure feedback loop is used to control the pump. It is possible to provide the system also with maximum, minimum and optimum (target) values for the pressure.

Inflation or deflation of the balloon in case of plac- ing a percutaneous valve stent-graft (Fig. 14) or stent-valve (Fig. 15) can either be done by hand as usual or can be done with a mechanical pump controlled by the system. The user can choose if he wants to deliver the stent or expand the valve manually or let the system do it. If so, he can control the ac- tion via real-time imaging of the working area and interrupt or slow down the automatic placement or take it over and finish the placement manually in case it is needed.

The delivery of the stent-graft or stent-valve can be performed using a deflectable guiding catheter either with ac- tive degrees of freedom or classic catheter. The user can choose to control the degrees of freedom manually or let the system do it.

It should be noted that even when the system is not on automatic mode, when the catheter is being inserted by hand, that the visualization system is always working, meaning than the surgical team always can have information of the location of the distal end of the catheter with the balloon and/or the stent inside the vascular system. This presents a major advantage in relation to the prior art. From the last point, it should be noted that the use of the invention or part of it is not exclusive to cardiac surgery but can be used to visualize and/or control other catheters in other interventions as well.

One preferred option for position measuring is the use of magnetic tracking. As seen in figure 7, a coil 7 is inserted in the catheter to sit in the middle point of the balloon 1. The magnetic tracking system provides 6 degrees of freedom, that is, 3 values for position and 3 values for orientation, position information. Of course, other tracking systems may be used to im- plement the invention.

In the preferred embodiment, a 3D dataset of the patient's thorax should be available. This dataset can be obtained by Computerized Tomography of Magnetic Resonance, for instance. The position in space measured by the magnetic tracking should preferably be matched numerically to the coordinates of the patient's dataset in a process known as registration.

Registration can, but doesn't necessarily have to, be done rigidly by placing the catheter with the sensor at known reference locations in the patient, and marking these locations in the dataset. The details of this process are not relevant to the invention and other methods of registration might also be used .

In the preferred embodiment, the system has the option to manually register or re-register different kinds of 2D or 3D images (most likely real-time images such as echography, an- giography) to the pre-operatively acquired 3D dataset of the pa^¬ tient .

After registration is completed successfully there is the guarantee that, apart from a measuring error, the position reported corresponds to the position in real space, within the measuring volume of the magnetic tracking system. With this, the distal end of the catheter can be represented embedded in the 3D dataset and also a virtual view of the balloon position can thus be created. This is what can be seen in the user interface of a preferred embodiment according with the present invention as seen in figure 8.

The correct information about the location in space of the catheter's distal end is also used to control its position. The difference between the position and the intended position is the position error. This difference is calculated in the piece of software that manages the data. The two software programs communicate and the error is passed on to the program that implements the feedback control loop. The control loop tries to minimize the error thus bringing the balloon closer to the in- tended position. To minimize the error, the control loop gener^¬ ates electrical signals to the actuator that will push or pull the catheter .

Additionally, the program that implements the control loop also preferably includes software for automatically reduc- ing the pressure within the balloon when a balloon is applied and is intended to being moved. Reducing the pressure within the balloon deflates the balloon, at least partially, which enables the balloon to be moved more easily and safer. After the balloon is located in the desired position, the pressure is increased to hold the balloon at the desired position. Such pressure increases and decreases are preferably performed automatically, and are controlled by the software. However, manually increasing and decreasing of the pressure is also contemplated. For the control of the pressure in the balloon, the pressure line of the Endoclamp Catheter ™ can be used and the pressure measured using a Strain Gauge Pressure Sensor, but also other kind of sensors can be used.

Figure 9 shows in a preferred embodiment the device used to physically control the movements of the catheter. The object is used to push or pull catheters or guidewires. The catheter driver is constituted by 6 or more rollers and a cen- tral pulley. The central pulley and the rollers can be with flat profile or with grooves. The central wheel and/or the rollers can be actuated manually or by motors. The catheter is placed between the rollers and the central pulley. The relative rota- tion of the central pulley respect to the rollers creates the motion of the catheter or guidewire. The control of the catheter driver is done via position or force feedback.

This design for the actuator is not exclusive and it should be noted that any way to automatically push and pull the catheter could be used in the scope of the invention to perform this action.

An example of another preferred embodiment is shown in Fig. 16.

Figure 16 shows in a preferred embodiment an actuator which can be used to physically control the movements of the catheter (push, pull and rotate) . It has a spindle 15 connected to an engine 16 with a moving part 17. The catheter is attached to the moving part via a grip 18 to perform pushing, pulling and rotating movements. This design for the actuator is not exclu- sive and it should be noted that any way to automatically push, pull and rotate the catheter could be used in the scope of the invention to perform this action.

Finally, in figure 11 we see how the information is flowing in this realization of the system. The catheter with the sensor is inside the patient, out of direct view. The magnetic tracking measures the position of the sensor in space and the 3D visualisation software acquires this data. The same software represents the catheter's distal end position (possibly with the balloon) on the screen by superimposing it with the pre- operative 3D images. The 3D visualisation software calculates the error between the catheter' s position and its desired position and passes on this error to the control loop that in turn will generate the appropriate signal to push or pull the catheter in order to minimize the error, as well as the appropriate control.

While various embodiments of the present invention have been shown and described, it should be understood that other modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art. Such modifications, substitu- tions and alternatives can be made without departing from the spirit and scope of the invention.

Claims

1. A system for positioning a distal end of a catheter at a predetermined location within a passage, and for maintaining said distal end at the predetermined location, the system comprising: a position sensor located at or near said distal end; location determining means for determining an actual location of said distal end of said catheter within the passage based on said position sensor; difference determining means for determining a difference between the actual determined location of said distal end of said catheter and said predetermined location; an actuator attached to said catheter for moving said catheter within the passage; controlling means for controlling said actuator; wherein, if said difference determining means determines a difference between the actual determined location of said catheter and said predetermined location, said controlling means controls said actuator to move said catheter to said pre- determined location.

2. The system, as defined in claim 1, wherein the distal end of the catheter is provided with a balloon, and said position sensor is located in or near to said balloon.

3. The system, as defined in claim 2, wherein there is a pressure sensor located in or on said inflatable balloon and said controlling means also controls inflation and deflation of said inflatable balloon, wherein further said controlling means is configured and arranged to automatically deflate said inflatable balloon, at least partially, when said actuator is moving said inflatable balloon, and said controlling means is configured and arranged to automatically inflate said inflatable balloon when said inflatable balloon is located at said predetermined location.

4. The system as defined in anyone of claims 1-3, wherein it is arranged for the delivery at the pre-determined location of a substance for medical treatment, and/or a medical treatment device.

5. The system according to claim 4, wherein the medical treatment device is a stent or a stent-valve.

6. The system according to claim 5, wherein the stent or stent-valve is positioned at a predetermined position by in^¬ flating the balloon.

7. The system according to anyone of claims 1-6, wherein there is a display that displays the actual location of the distal end of said catheter within the passage.