Patent Application
20120296196
This application claims priority of German application No. 10 2011 076 217.5 filed May 20, 2011, which is incorporated by reference herein in its entirety.
The invention relates to a method for assisting a person performing a minimally invasive intervention with a catheter involving a puncture of a septum, in particular of a heart, and an X-ray device.
Mitral valve insufficiency, often also called “mitral regurgitation”, is a cardiac valve defect that may occur in humans. It involves an inability to close or a “leakiness” of the mitral valve of the heart, which, during the so-called ejection phase (systole), leads to a reverse flow of blood from the left ventricle into the left atrium.
The mitral valve functions as a valve between the left atrium and the left ventricle of the heart. In the filling phase (diastole) of the ventricle, it opens and thus enables the inflow of blood from the left atrium. At the onset of the ejection phase (systole), the suddenly rising pressure in the ventricle leads to closure of the mitral valve and thus to a “sealing off” of the atrium. In this way, the pressure in the atrium is only about 8 mmHg, while, at the same time, in the ventricle the systolic pressure of approximately 120 mmHg drives the blood into the main artery (aorta) in the usual way.
To classify mitral insufficiency by degrees of severity, it is known to differentiate between three or four degrees, for example mild, moderately severe and severe mitral insufficiency. In the case of mild mitral insufficiency, the physiological processes are only slightly affected and neither the extent of the leakiness or (regurgitation opening) nor the quantity of blood flowing back (regurgitation volume) reach degrees that could lead to an anomaly of the pressure in the left atrium and in the pulmonary veins and the pumping capacity of the heart.
Severe mitral insufficiency, which can, for example, be defined as a regurgitation opening of more than 40 mm2 and a regurgitation volume of more than 60 ml, can result in serious and sometimes life-threatening changes. In such cases, there is principally a considerable increase in the pressure in the atrium and hence also in the pulmonary veins, wherein the pressure can be as high as 100 mmHg, which, even when the pulmonary vessels are in a normal condition, can result in immediate pulmonary edema. In addition, the resulting predominant reverse flow of blood can cause inadequate ejection output into the aorta and consequently deficient perfusion of other organs. Such problems occur in the acute stage.
If the acute stage is withstood or if the mitral insufficiency develops over a longer period of time, the result is a series of chronic adaptation processes in the heart and the pulmonary vessels. Persistent pressure and volume loading of the atrium causes the enlargement thereof, wherein the atrium volume can often triple or quadruple in size within months or years. Over the course of time, this dilation also reduces the pressure-increasing effect of the regurgitation volume in pulmonary circulation. In addition, the pressure loading also causes an enlargement of the left ventricle, which now, with every heart beat, in addition to the actual quantity of blood required, also has to pump the regurgitation volume. Although, by means of the so-called Frank-Starling mechanism, this dilation is able, on the one hand, to increase the stroke volume, it leads, on the other hand, to a “vicious circle”, if on the expansion of the ventricle, the geometry of the mitral valve is also disturbed and in this way its insufficiency is increased still further.
In order to avoid serious and high-risk interventions as far as possible in the case of mitral valve insufficiency, researchers have turned to the field of minimally invasive cardiac valve interventions. For this, it has been suggested that a clip be used to in order to clamp together the leaflets of the mitral valve in a minimally invasive way. A clip of this kind is known under the name MitraClip and is described, for example, in more detail in US 2005/0149014 A1 and US 2006/0184203 A1. The procedure for using a clip device of this kind is described, for example, in the article “Step-by-Step Guide for Percutaneous Mitral Leaflet Repair” by Mehmet Cilingiroglu et al., Cardiac Interventions Today, edition dated July/August 2010, pages 69-76. According to this, the aforementioned MitraClip is used to clamp the leaflets of the mitral valve in a minimally invasive intervention. This results in better closure of the mitral valve and prevents or reduces the reverse flow of blood from the left ventricle to the left atrium.
The procedure described in the cited article uses an X-ray device with a C-arm to record fluoroscopic images and an ultrasound device; the MitraClip is brought to the site to be treated by a guide catheter. The workflow described therein entails the introduction of the guide catheter into the right atrium using fluoroscopy, following which the septum (the partition wall) of the heart is punctured using fluoroscopy and ultrasound imaging in order to move the guide catheter from the right atrium into the left atrium. Again using fluoroscopy and ultrasound imaging, the MitraClip is positioned above or on the leaflets of the mitral valve. Finally, the MitraClip is clamped on the leaflets of the mitral valve, following which the tightness of the closed mitral valve and the permeability of the open mitral valve are checked using Doppler ultrasound imaging, wherein repositioning may be necessary. If the results are satisfactory, the MitraClip is finally secured and the catheter can be removed again under fluoroscopic monitoring, wherein it is possible to check in a final fluoroscopic image whether all the catheters and tools have been completely removed.
One drawback of these devices and the associated workflow is the fact that fluoroscopy and ultrasound imaging (frequently echocardiography through the esophagus, “transesophageal echocardiography—TEE”) are not able to depict the anatomy of the right and left atria sufficiently well. Therefore, it is, on the one hand, difficult to identify a suitable puncture site in the septum and, on the other, it is difficult to check how far the catheter reaches into the left atrium so that there is a risk of damage to the left wall of the atrium. If the puncture site is poorly chosen, for example too high or too low, there is a risk that, due to the restricted mobility of the catheter, the MitraClip cannot be correctly positioned or correctly secured on the mitral leaflets.
The aforementioned article by Mehmet Cilingiroglu et al. refers to the importance of optimum positioning of the transseptal puncture with respect to the outcome of the procedure: “Because of the need to approach the mitral valve at appropriate angles in all three planes of the valve to ensure successful and adequate grasping of the mitral leaflets, it is critical that the transseptal puncture is placed relatively posterior and relatively high in the fossa ovalis. This high puncture allows an adequate working space and distance above the mitral leaflets (ideal height from the annulus should be 3.5-4 cm) for the delivery catheter manipulations, clip opening, and clip retraction during the grasping.”
The later-published US patent application with the U.S. application Ser. No. 12/881,925 of the applicant, the disclosure content of which is fully incorporated by reference into the disclosure content of the present invention, describes a device and a method for minimally invasive therapy of mitral regurgitation and proposes that it is no longer mandatory to use an ultrasound device, but instead an X-ray device with a C-arm can be used in order to take both CT-like and fluoroscopic images, wherein a CT-like image is superimposed on a fluoroscopic image during the use of the catheter. Here, it can be provided that segmentation is performed and is also visible in the superimposed representation. The superimposed data is used to assist the guidance of the catheter. Therefore, although it is suggested that features are extracted from the three-dimensional CT-like image data record by segmentation which can then be superimposed on fluoroscopic images, even this does not disclose a specific, advantageous variant for finding a suitable puncture site.
The invention is therefore based on the object of disclosing an improved method for assisting in the identification and use of a suitable puncture site.
To achieve this object, according to the invention, the following steps are provided with a method of a type named in the introduction:
It is, therefore, proposed that a three-dimensional image data record in particular of the heart be used to determine essential information to enable the correct puncture of the septum. It is possible, on the one hand, to determine, either manually or preferably automatically, septum information that describes the position of the septum in three-dimensional space at least approximately. This determination of the position of the septum as an anatomical structure can now be further supplemented by additional information, which influences or even shows the selection of the puncture site and which is derived from the position of at least one anatomical structure. However, it is also conceivable that the additional information is determined and superimposed regardless of the position of the septum, that is also without the determination of septum information, wherein then the person performing the intervention can himself identify the position of the septum from the image. Therefore, a manual or preferably automatic evaluation of the three-dimensional image data record is performed which results in the additional information, which is, for example, an auxiliary line or another auxiliary superimposition, which assists in the selection of the puncture site and the guidance thereto. In particular, a desired puncture site can itself be specified as additional information, in particular during planning, at least partially automatically. Suitable superimposition of the septum information and the additional information into the current fluoroscopic images, from which the position of the catheter is evident, provides the person performing the intervention with an excellent aid that improves the guidance of the catheter in that the difficult task of selecting and finding the puncture site can be made much easier for him.
It is therefore possible according to the present invention to plan the puncture site on a three-dimensional representation of the three-dimensional image data record, that is the relevant heart structure, and to visualize this planning optimally to the person performing the intervention on the fluoroscopic image as guidance. This enables a better selection of a puncture site and more precise guidance of the catheter to the puncture site.
The method according to the invention can be used particularly advantageously for the treatment of mitral valve insufficiency. As described in the introduction, in this case it is, for example, conceivable, to clamp together the leaflets of the mitral valve, in particular by means of a MitraClip. To do this, it is necessary, to go from the right atrium through the septum into the left atrium of the heart. In this context, it can with particular advantage be provided that, when treating mitral valve insufficiency, in particular when clamping together the leaflets of the mitral valve, as an intervention, at least one item of mitral valve information is determined describing the position of the mitral valve and at least one item of additional information is derived therefrom. In the case of an intervention on the mitral valve, the relevant anatomical structure is, therefore, the mitral valve itself, wherein, in the example of the application of a MitraClip to the leaflets of the mitral valve, it is necessary to navigate very precisely with the catheter, wherein this has to be introduced into the left atrium and then can, for example, be bent so that the MitraClip ideally lies precisely in the region of the closing mitral leaflets. Therefore, as already explained in the representation of the prior art, the distance of the puncture site from the mitral valve, in particular the height above the mitral valve, can play an important role.
In order to facilitate improved planning and guidance, it can be provided that the mitral valve information is determined as the course of the annulus of the mitral valve and from this additional information is determined, allowing for a predefined distance and/or distance range, as a one- or two-dimensional orientation range of the septum and/or the wall of the left atrium and/or an orientation plane intersecting the septum and/or the wall of the left atrium. Therefore, when the position of the mitral valve has been determined as an anatomical structure, it is proposed that this be described by the course of the annulus, that is of the edge, of the mitral valve. This is used as a basis in order to determine, as additional information, for example, an orientation range, in which the puncture site should ideally lie, or an orientation plane, the line of intersection whereof with the septum (as a one-dimensional orientation range) offers orientation when identifying a suitable puncture site. If this additional information is determined at an early stage, it is possible, for example by manual interaction in the planning phase, in particular in a three-dimensional representation of the anatomy, on the basis of the three-dimensional image data record, to determine manually or also automatically an optimal puncture site as further additional information.
In a concrete embodiment of the present invention, it is suggested that a mitral valve plane derived from the course of the annulus is determined, wherein the orientation range and/or the orientation plane are at the predetermined distance or distance range from the mitral valve plane. A plane of this kind can be determined from the annulus of the mitral valve, which usually has an approximately saddle-like shape, for example as an equalization plane using methods that are known in principle, but other possibilities are also conceivable, for example the selection of at least three points through which the plane should extend or the like. It is then particularly simple to use the predetermined distance or distance range. When positioning a MitraClip, a preferable predetermined distance or distance range is in particular a distance from three to five centimeters, for example 3.5-4 cm, as suggested in the article by Mehmet Cilingiroglu et al. cited in the introduction. However, it is also noted at this point that the optimal puncture site does not necessarily have to lie in the center of the orientation range inside the septum or in the center of the line of intersection of the orientation planes with the septum.
In a particularly advantageous embodiment of the present invention, it can also be provided that further intervention information relevant for the intervention is determined in the image data record and shown superimposed on the current fluoroscopic image. Therefore, further concrete embodiments are conceivable to simplify the planning and the navigation for the person performing the intervention and permit a more exact intervention. For example, it can be provided that risk information showing a position of regions at risk from the catheter, in particular the auricle and/or the pulmonary veins, is used as intervention information. In particular in the example of the positioning of a MitraClip, here reference is made to the auricle and the pulmonary veins, which are at risk if the catheter is inserted too far into in the left atrium. Therefore, such regions can be particularly advantageously shown highlighted in the fluoroscopic image in order to avoid problems here at an early stage. It is further advantageous for navigation information showing the position of a navigation target, in particular a valve line to which the leaflets of the mitral valve are connected, and/or the surrounding anatomy, to be determined. In an intervention to rectify a mitral valve insufficiency, it is particularly advantageous to extract navigation information describing the valve line (coaptation line), wherein this determines, for example, how a catheter bearing a MitraClip should be correctly oriented. Therefore, additional information of this kind also enables an important display providing improved assistance to the person performing the intervention. However, further anatomical structures in the environment could also serve as navigation aids and hence corresponding navigation information can also be determined in this regard.
To determine the position of at least one anatomical structure in the three-dimensional image data record, advantageously segmentation and/or the use of an anatomical atlas can be provided, wherein particularly advantageously the determination is performed at least partially automatically. Basic procedures for the automatic and/or manual segmentation of anatomical structures are known. In particular in cases where anatomical structures cannot be determined with sufficient clarity from the image data record, it can be advantageous to refer to an anatomical atlas in order to be able to at least approximate their position. If, for example, an intra-operative image data record recorded with an X-ray device with a C-arm is used as a three-dimensional image data record, frequently the septum cannot be clearly identified therein so that here it may be advantageous to refer to an anatomical atlas and then to approximate the septum, for example with a simple shape such as a circle or an ellipse. This is also conceivable with other anatomical features, for example the annulus of the mitral valve, which can be approximated as a circle, or the like. Concrete algorithms for segmentation in three-dimensional image data records do not need to be explained in more detail here since they are already known to the person skilled in the art from the prior art.
A preoperative magnetic resonance image data record and/or a computed tomography image data record and/or an ultrasound image data record can be used as a three-dimensional image data record, wherein in principle obviously also a plurality of three-dimensional image data records can be used. In this case, preoperative image data records generally have the advantage that they are selected such that the relevant anatomical structures can be clearly identified and therefore simple, in particular fully automatic, segmentation is enabled. However, in this case another registration with the fluoroscopic images is necessary so that it can be provided that, when using a preoperative image data record, registration is performed with the fluoroscopic images by 3D-2D registration or by 3D-3D registration with a three-dimensional registration data record recorded by means of the X-ray device used to record the fluoroscopic images.
Methods for 3D-2D registration and for 3D-3D registration are already known in principle from the prior art. If a registration data record, which can also be used as an image data record, is to be recorded, the X-ray device used to record the fluoroscopic images can advantageously be an X-ray device with a C-arm so that a CT-like (computed-tomography-like) registration data record can be generated in that projection images are recorded from different projection directions and reconstructed to form a three-dimensional registration data record. A registration data record of this kind to be recorded on a patient who is already in position directly before the intervention is advantageously generated at a low dose.
However, additionally or alternatively it is also conceivable for the three-dimensional image data record to be recorded at the site of intervention by means of a X-ray device comprising a C-arm, which is also used to record the fluoroscopic images. In this case, only one single image recording device, namely the X-ray device, is necessary, wherein a rotation of the C-arm enables the recording of projection images from different directions from which a CT-like three-dimensional image data record can be reconstructed. Since the fluoroscopic images are also recorded with the X-ray device and the three-dimensional image data is recorded with a patient who is already in position, that is intraoperatively, no further registration is required. The data are registered inherently with each other.
In a particularly expedient development of the method according to the invention it can further be provided that, when using a X-ray device adjustable for different projection directions, in particular comprising a C-arm, to record the fluoroscopic images, at least one projection direction to record the fluoroscopic images is determined and adjusted automatically as a function of the septum information and/or at least one item of additional information and/or determined manually with reference to a representation of the three-dimensional data record and/or the septum information and/or the additional information. It is therefore advantageously conceivable to select a suitable C-arm angulation based on the extracted structures and additional information so that the fluoroscopic images represent an ideally suitable viewing direction for the current phase of the intervention. In this case, the determination does not mandatorily have to take place automatically; it is also possible that for this to take place manually with reference to a representation of the three-dimensional image data record or a representation derived therefrom. Then, for example, the representation can be turned in a specific direction, which the person performing the intervention wishes to see. A projection direction, and hence an angulation, of the C-arm, is then automatically determined and actuated.
In this case, it is advantageous if, to assist the puncture of the septum, a first projection direction standing perpendicularly to the septum and/or parallel to a plane dependent upon the position of the mitral valve, in particular parallel to the mitral valve plane and/or the orientation plane, is selected. In a projection direction of this kind, ideally standing perpendicularly to the septum, it can be checked in an excellent way whether a planned or currently desired puncture site has actually been correctly reached. Since the necessary backgrounds are known anyway from the septum information and the additional information, this adjustment can particularly advantageously take place automatically as can the preceding determination of the optimal projection direction.
In this context, it is further expedient for at least one fluoroscopic image from another second projection direction, in particular standing perpendicularly to the first projection direction, to be recorded and displayed. This is particularly useful if it is advisable to check from another direction, if, therefore, it is to be determined, for example, whether the catheter has already moved from the right atrium into in the left atrium or how far it has advanced, in particular also with respect to risk information, as already described above. Such control recording is preferably performed parallel to the septum so that a puncture of the septum is easily identified.
In this context, reference is made to the fact that with the method according to the invention, in particular with respect to the exemplary embodiments showing the angulation of the C-arm of an X-ray device derived from the information, it can be advantageous to use a biplane-X-ray device since then it can, for example, be provided that fluoroscopic images can be recorded perpendicularly to the septum and parallel to the septum simultaneously hence achieving optimal orientation for the person performing the intervention.
In addition to the method, the invention also relates to an X-ray device comprising a control device designed to carry out the method according to the invention. This is particularly advantageously an X-ray device with a C-arm opposite to which an X-ray tube and X-ray detector are arranged. The C-arm can be swiveled around a patient positioned on a patient bed so that projection images can be recorded from different projection directions from which the three-dimensional image data record can then be reconstructed. In addition, different angulations of the C-arm are possible from which the fluoroscopic images can then be recorded. The control device is particularly advantageously embodied to determine the septum information, the additional information and optionally further information from the three-dimensional image data record at least partially or even wholly automatically and to display it at least partially additionally to the fluoroscopic images and superimposed thereon, for which a corresponding display and operating device is provided. All embodiments relating to the method according to the invention can be similarly transferred to the X-ray device according to the invention so that these are also able to achieve the advantages of the present invention.
Further advantages and details of the present invention will emerge from the exemplary embodiments described below and with reference to the drawing, which shows:
The present invention will now be discussed using the example of a minimally invasive intervention in which the leaflets of the mitral valve are to be clamped together by means of a so-called MitraClip in order to treat mitral valve insufficiency. Here, a guide catheter is used, which is initially introduced into the right atrium of the heart where the septum is punctured and the catheter is then guided into the left atrium from where the actual treatment is performed. Here, it is important that the puncture of the septum takes place at a suitable puncture site, for which the method according to the invention provides a plurality of assistance options, wherein however, assistance options extending beyond the object of the present invention are also provided during the performance of the minimally invasive intervention.
The operation of the X-ray device 1 is controlled by a control device 7, which not only the controls the image recording but is simultaneously designed to evaluate image data and to generate suitable representations to be displayed, specifically to carry out the method according to the invention, which will be described in more detail below.
Initially, in a step 16, a three-dimensional image data record of the heart, in particular of the left atrium, is recorded. In this case, there are substantially two possibilities. On the one hand, it is conceivable to record the three-dimensional image data record preoperatively, for example as a magnetic resonance image data record, a computed tomography image data record or an ultrasound image data record. Alternatively or additionally, it is preferred according to the invention to use the current information to record an intraoperative three-dimensional image data record with a patient 6 who is already in position by means of the X-ray device 1.
In a step 17, the annotation and the planning of the minimally invasive intervention are performed. For this, initially, anatomical structures are segmented, preferably automatically by the control device 7, in such a way that their position is known and further information can be derived therefrom. In addition to the actual three-dimensional image data record, here account is taken of data from an anatomical atlas 18, for example in order to be able to identify the septum at least approximately if the septum 13 cannot be clearly identified on the three-dimensional image data record recorded by the X-ray device 1.
In this case, the position of the following relevant anatomical structures is determined by segmentation or approximation: left atrium 9, mitral valve 10, septum 13, auricle 14 and pulmonary veins 15, wherein obviously other further anatomical structures can also be considered. Septum information indicates the position of the septum 13. Corresponding further information is available with respect to the wall of the left atrium 9, the mitral valve 10, the auricle 14 and the pulmonary veins 15.
In a step 19, this position information, which is already available, is now further processed in order to determine additional information with respect to the septum puncture and intervention information, concrete risk information and navigation information.
This is explained in more detail by the schematic representation in
Now, it is known that it is advantageous to introduce the catheter 8 into the left atrium 9 at a certain distance or distance range above the mitral valve plane 21. In the example shown in
It is noted at this point that additional information, which in the present case is determined completely automatically by the control device 7 can also, in particular in conjunction with the three-dimensional image data record or a representation derived therefrom, be displayed to the person performing the intervention for purposes of further planning, who can then, for example, also manually select as further additional information a desired puncture site as one of the points of intersection 24. However, an automatic determination of a puncture site by the control device 7 is also conceivable.
In the present case, further useful intervention information for assisting the person performing the intervention is derived, wherein, in the present case, the position of the actual pulmonary vein 15 represents risk information, exactly like the boundary 25 of the auricle 14, since these anatomical structures should not be damaged by the catheter 8 during the intervention, that is they indicate regions that are better avoided. As further navigation information (as part of the intervention information), in the present case, the valve line 12 is automatically determined by the control device 7, which represents important information with respect to the orientation of the catheter 8 and therefore of the MitraClip.
In a step 28, the planning is then completed and the actual intervention with the catheter 8 starts. Then, in an optional step 29, if a preoperative three-dimensional image data record was used, a registration of the preoperative three-dimensional image data record (and therefore of the information determined) with the fluoroscopic images to be recorded is achieved, for example by a known 3D-2D registration algorithm or by a 3D-3D registration algorithm in conjunction with a three-dimensional registration data record recorded by means of the X-ray device 1. If a three-dimensional image data record of the X-ray device 1 recorded anyway on a patient 6 already in position is now used as the three-dimensional image data record, no further registration is required since the same X-ray device 1 is used.
While the intervention is now being performed, which means the catheter 8 is brought to the mitral valve 10, continuous monitoring is performed by recording fluoroscopic images and displaying these on a display device of the X-ray device 1, for example a monitor. This takes place in step 30. Here, initially the catheter 8 is introduced into the right atrium of the heart under fluoroscopic monitoring. From this time at the latest, at least a part of the information determined is displayed superimposed on the current fluoroscopic image as is explained in more detail for example by
It is advantageous if, at the latest after the puncture of the septum 13 and the penetration of the catheter 8 into the left atrium 9, another setting is selected, for example a setting running substantially parallel to the septum 13, as indicated by
It should also be noted at this point that it also possible within the scope of the present invention to work without septum information so that only the additional information is determined and superimposed on the image. For example, here, a plane or a circular area of a specific size can be determined above the mitral valve and superimposed on the fluoroscopic images without concrete details of the location of the septum.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102011076217.5 | May 2011 | DE | national |
