Abstract:
Medical treatment device with an ablation catheter and a visualization device for joint display of the ablation catheter and the anatomy of a part of a patient&#39;s body to be treated, whereby the visualization device is embodied for detection of areas of risk of the part of the body to be treated and for displaying the areas of risk jointly with the ablation catheter and the anatomy.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims priority of German application No. 10 2005 045 363.5 filed Sep. 22, 2005, which is incorporated by reference herein in its entirety.  
       FIELD OF THE INVENTION  
       [0002]     The invention relates to a medical treatment device with an ablation catheter and a visualization device for jointly displaying the ablation catheter and the anatomy of the part of a patient&#39;s body to be treated.  
       BACKGROUND OF THE INVENTION  
       [0003]     The use of medical treatment devices in electrophysiological procedures is known. In such cases one or more catheters are introduced for the purpose of electrophysiological mapping or for performing an ablation into anatomical areas of the body of a patient, especially in the heart. An ablation, i.e. a removal of intracardiac tissue, is performed with the aid of an ablation catheter in order to provide permanent therapies for arrhythmias.  
         [0004]     However ablation involves a not-insignificant risk for the patient during use close to risky areas, of causing irreparable undesired injuries by the ablation. For treating atrial fibrillation the ablation on the posterior wall of the left atrium can cause a perforation of feed pipes, if the ablation is carried out in the vicinity of the feed pipes against the epicard. Similarly ablation in the vicinity of the pulmonary veins opening out into the left atrium can cause stenoses of the pulmonary veins. Generally ablation in the vicinity of heart valves (mitral valve, tricuspid valve) or in the vicinity of vessel valves (aorta valves, vein valves) can cause valve stenoses or other damage to the valves.  
         [0005]     To limit the risk of injuries to the patient as much as possible it is already being proposed that ablation should not be performed exclusively in accordance with electrophysiological criteria, but should also include anatomical criteria. Thus atrial fibrillation is no longer treated by circular lesions around the pulmonary veins in the immediate vicinity of the pulmonary veins, with the risk of causing stenoses of the pulmonary veins, but instead linear lesions are made in the antrum of the left atrium further away from the mouths of the pulmonary veins. Electroanatomical mapping systems are used for this purpose in order to visualize the ablation catheter during the ablation procedure in a representation of the cardiac anatomy.  
       SUMMARY OF THE INVENTION  
       [0006]     The problem underlying the invention is thus that of specifying a medical treatment device with which ablations can be carried out with a reduced risk of injury to the patient.  
         [0007]     To resolve this problem there is provision in accordance with the invention, with a medical treatment device of the type mentioned at the start, for the visualization device to be embodied for detection of areas of risk of the part of the body to be treated and for display of the areas of risk jointly with the ablation catheter and the anatomy.  
         [0008]     The invention is based on the knowledge that the risk of injuries can be significantly reduced if both the region to be treated, for example a heart chamber, and also anatomical risk areas, for example pulmonary veins, the feed tubes, heart or vessel valves, can be jointly mapped by a visualization device or an electroanatomical mapping system. This produces a real-time visualization of the ablation catheter jointly with the region to be treated and areas of risk. In this way an electrophysiologist is able to see the position of the ablation catheter relative to areas of risk. He can thus carry out the treatment with corresponding care in the vicinity of these areas of risk or he can position the ablation in a less dangerous area. In individual cases he can also decide not to carry out any ablation at all in a risk area.  
         [0009]     For the inventive treatment device there can be provision for the visualization device to be embodied for continuous display. Accordingly the ablation catheter, the anatomy of the patient and areas of risk are permanently displayed for the user. This process visualization in real time provides a continuous current image of the area to be treated which reduces the risk of injuries.  
         [0010]     It is also within the scope of the invention for the real-time display of the inventive treatment device to be based on intraprocedural 2D imaging or pre-procedural 3D imaging. The use of intraprocedural 3D imaging is preferred however. Where 2D real-time imaging is used, this can be based on intracardiac and/or intraesophageal ultrasound and/or on an x-ray image. Where 3D real-time imaging is used, this can be based on intracardiac ultrasound. Where pre-procedural 3D imaging is used, this can be based on computer tomography examination and/or a magnetic resonance examination and/or an x-ray rotation angiography examination. Pre-procedural 3D imaging is preferably used with relatively movement-invariant structures such as the pulmonary veins for example.  
         [0011]     The visualization device of the inventive treatment device can be embodied for carrying out an image registration and/or image diffusion of the display of the ablation catheter and the anatomy of the part of the body to be treated and of the risk areas. This enables both 2D and 3D data to be registered as well as pre-procedural image data with intraprocedural image data.  
         [0012]     To guarantee the function of the inventive treatment device it can be embodied for extraction of the areas of risk from the display of the anatomy, with an area of risk preferably being embodied as a point, line, surface or as a volume. The important aspect here is that the extraction of areas of risk is undertaken automatically, so that this is a permanent process not requiring any user input.  
         [0013]     In a further embodiment of the invention there can be provision for the treatment device to be embodied for determining a degree of risk with reference to the distance between the extracted area of risk and the ablation catheter. The distance between the ablation catheter and the area of risk is used in this case as a criterion for assessing the danger. A small distance in such cases corresponds to a higher level of danger, conversely a larger distance corresponds to a lower level of danger.  
         [0014]     To avoid injury to the patient there can be provision in the inventive treatment device, if a limit value for the degree of danger is exceeded, for a warning signal to be output. The requirement for this is that the degree of danger is calculated continuously in real time, which in its turn requires a continuous recording of the current position of the ablation catheter and of the area or areas of risk. If the limit value is exceeded, a visual and/or audible and/or tactile warning signal can be output. This warning signal allows the user to slow down at the ablation procedure and/or emit less energy to be tissue to be ablated, to break off the procedure entirely or to carry it out at a less dangerous location. Especially preferred is an audible and/or tactile warning signal which can be perceived particularly easily by the user.  
         [0015]     In a further embodiment of the invention there can be provision for the intensity of the warning signal to be modified depending on the degree of danger. In this way a progressive warning signal is obtained, in which case, with an audible warning signal for example, the volume increases as the degree of danger becomes greater. In a similar way the tactile feedback can become stronger as the degree of danger increases.  
         [0016]     To ensure an especially low-risk treatment there can be provision in the inventive treatment device for the function of the ablation catheter to be influenced depending on the degree of danger. In this case the part of the ablation catheter and/or the duration of its effect and/or the temperature on ablation and can be reduced in particular. If the degree of danger is particularly high the ablation catheter can also be switched off automatically.  
         [0017]     In addition the invention relates to a method of operation for a medical treatment device with an ablation catheter and a visualization device for a joint display of the ablation catheter and the anatomy of a part of the body of a patient to be treated.  
         [0018]     The inventive method for operation of the medical treatment device comprises the following steps:  
         [0019]     Displaying at least one area of risk, calculating the degree of danger, if a threshold value is exceeded for the degree of danger, outputting a warning signal. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]     Further advantages and details of the invention will be explained on the basis of an exemplary embodiment which refers to the figures. The figures are schematic diagrams and show:  
         [0021]      FIG. 1  the joint visualization of ablation catheter, heart chamber and areas of risk during use of the inventive medical treatment device, and  
         [0022]      FIG. 2  the layout of the inventive medical treatment device. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0023]      FIG. 1  shows the joint visualization of ablation catheter, heart chambers and areas of race at when the medical treatment devices being used.  
         [0024]     The diagram shows the left atrium  1  of a patient&#39;s heart, pulmonary veins  2  to  5  and the esophagus  6 . Likewise an ablation catheter  7  is shown, with which atrial fibrillation can be treated by cauterization of intracardiac tissue.  
         [0025]     As shown in  FIG. 1 , both the region to be treated, namely the heart chamber, and also the anatomical areas a risk, namely the pulmonary veins  2  to  5  and the esophagus  6 , are mapped by an imaging system. The esophagus  6  is among the areas of risk for which movement is possibly variable, thus intraprocedural 2D and 3D real-time imaging is used in such cases. To this end and intracardiac ultrasound system (ICE) is used which delivers two-dimensional or three-dimensional images of the left atrium. Optionally the esophagus can also be mapped with the ICE-US system in addition to the cardiac anatomy. In addition a transesophageal echocardiography ultrasound system (TEE) can be used which delivers a corresponding visualization of the esophagus  6 . If the intervention concerned only affects the pulmonary veins  2  to  5 , these could also be mapped with pre-procedural 3D imaging, e.g. with a conventional x-ray system. The process visualization of the esophagus through pre pre-procedural 3D imaging is also possible, if the movement variance of the esophagus is estimated to be insignificant.  
         [0026]     A registration and subsequently an image fusion are carried out by the treatment device in order to combine the different image data or representations. This is done using normal registration methods for a 2D-3D or a 3D-3D registration. As shown in  FIG. 1 , the electrophysiologist can recognize the current position of the ablation catheter  7  relative to potential areas of risk and perform the ablation with the appropriate care in the vicinity of these areas of risk, e.g. by a reduced ablation time or a reduced ablation power. Provided it makes sense in medical terms, the ablation can also be performed at a slightly offset location or not at all.  
         [0027]     Areas of risk  8 ,  9 ,  10  are extracted by the medical treatment device from the recorded image data. An area of risk can be a surface, for example the area of risk in the case of the esophagus  6  can be defined by a surface. With a heart valve the area of risk can be defined by a specific point. In the area of the mouths of the pulmonary veins  2  to  5  the area of risk can also be a three-dimensional surface. Areas of risk can also be represented as flat surfaces (e.g. cross section of pulmonary veins) or as lines (e.g. center line of the esophagus).  
         [0028]     In the exemplary embodiment shown real-time imaging is used for mapping the areas of risk  8 ,  9 ,  10 , the extraction of the areas of risk is thus also undertaken continuously during the ablation procedure, meaning that the visualization and the determination of the areas of risk  8 ,  9 ,  10  is constantly being updated.  
         [0029]     A mapping of the esophagus is achieved by swallowing a stomach probe with a corresponding sensor of the mapping system. The surface or the position of the areas of risk  8 ,  9 ,  10  can be identified by this position sensor, the relative position of the area or areas of risk to the position of the ablation catheter  7  can then be determined at the same time. This gives the user a visualization of the anatomy, of the areas of risk  8 ,  9 ,  10  and of the ablation catheter  7 .  
         [0030]     Since the relative position of the ablation catheter  7  to the areas of risk  8 ,  9 ,  10  is known, the treatment device can give the user feedback about this spatial relationship. In this case the distance between the current position of the ablation catheter  7  or its tip and the surface or position of an area of risk  8 ,  9 ,  10  is determined. If this distance falls below a predetermined limit value the ablation catheter  7  can be blocked, meaning that the power can be reduced, alternatively or additionally the temperature can be reduced or the ablation catheter  7  can switched off entirely. The primary aim of this is to give the user a warning, and therefore the blocking of the ablator can be cancelled by active operation of a user interface.  
         [0031]     If the distance between the current position of the ablation catheter  7  and the position or the surface of areas of risk  8 ,  9 ,  10  falls below a predetermined limit value, a visual, tactile or audible signal is output.  
         [0032]     In the medical treatment device different threshold values are provided for different areas of risk, different applications and for the imaging modalities used in each case for mapping the areas of risk. Likewise the limit values can be configured or set differently for different users or user groups.  
         [0033]     The visual warning signal can be reproduced at one or more of the medical systems used during the ablation procedure, e.g. at the x-ray system, at an electromagnetic mapping-system or at an electrophysiological recording system.  
         [0034]     A tactile warning signal is output if the catheter is being guided with remote navigation, e.g. with a magnetic remote navigation system or a mechanical remote navigation system. In these cases the tactile feedback can be provided to the user via a user interface of the remote navigation system. The user interface can be a joystick or a 6D mouse for guiding the catheter for example.  
         [0035]     The warning signals or the power reduction for safety reasons is tailored to the different uses, this feedback or the blocking of the ablation catheter  7  is thus only initiated after a specific power has been output or if the ablation catheter has a specific temperature. Where a limit value for the distance between the position of the ablation catheter  7  and the surface or position of an area of risk  8 ,  9 ,  10  is undershot, the duration of the ablation or power output is automatically limited.  
         [0036]      FIG. 2  shows the layout of the medical treatment device.  
         [0037]     Since the interaction of different medical engineering systems, devices and components which are used in an electrophysiological procedure is required for the treatment device  11  for imaging, 3D-3D registration, determining distances from areas of risk, the treatment device  11  includes a communication interface  12  embodied as a data bus, via which information is exchanged between the different medical engineering systems, terminals or components involved which are used for electrophysiological ablation procedures. This information or messages is transmitted synchronously or asynchronously and contains status notifications, ECG information 2D or 3D information about anatomical or image-based features determined or position or orientation of instruments, registration information for reconciliation and for registration of device-internal coordinate systems or device-internal configuration information.  
         [0038]     To achieve ongoing joint visualization of the heart chamber to be treated, the areas of risk and the position of the ablation catheter  7 , an electroanatomical mapping system  13  is provided in the exemplary embodiment shown, in addition 2D real-time imaging is provided. In addition an x-ray system  14  and a intracardiac ultrasound system (ICE)  15  are also used. Furthermore a Transesophageal echocardiography system (TEE)  16  can be connected to the communication interface  12 . In addition the ablation catheter  7 , a stimulator  17  and an electrophysiological recording system  18  are networked with each other via the communication interface  12 .  
         [0039]     The treatment device keeps the user informed continuously during an electrophysiological ablation procedure about the distance between the ablation catheter  7  and areas of risk  8 ,  9 ,  10 . If necessary precautionary measures are taken automatically by the device, which prevent or restrict ablation in the vicinity of areas of risk  8 ,  9 ,  10 . In this way the risk of injury to the patient in ablation procedures is significantly reduced.