Method and device for determining a spatial distribution of cardiac function parameters

Abstract

The invention relates to methods, devices, systems and computer program products for determining a spatial distribution of a cardiac function parameter. The spatial distribution of the cardiac function parameter comprises values of the cardiac function parameter along a plurality of spatial directions. The method comprises the steps of: providing electrocardiography data which allows for the determining of a time curve of length and direction of a sum vector; determining a time curve for each of a plurality of components of the sum vector from the electrocardiography data, wherein each component is associated with a respective one of the plurality of spatial directions; determining a plurality of values of the cardiac function parameter for the plurality of spatial directions, wherein a value of the cardiac function parameter is determined for each of the spatial directions from the respective time curve of the associated component of the sum vector, thereby obtaining the spatial distribution of the cardiac function parameter.

Description

[0001] METHOD AND DEVICE FOR DETERMINING A SPATIAL

[0002] DISTRIBUTION OF A CARDIAC FUNCTION PARAMETER

[0003] Description

[0004] Field of invention

[0005] The present invention relates generally to methods, computer program products, devices and systems for determining spatial distributions of cardiac function parameters based on electrocardiography data.

[0006] Background of the invention

[0007] A spatial distribution of activation time can be determined, for example, using an electrocardiography vest. An electrocardiography vest is usually not used for diagnostic purposes, but rather in combination with imaging techniques.

[0008] An electrocardiography vest comprises numerous electrodes (in one example, 252) that are placed on the body. The electrical potentials are measured simultaneously and displayed as a map. To determine the positional relationship between the vest and the heart, the electrocardiogram is projected onto a CT / MRI scan. For this to work, the electrocardiography vest must be worn during the scan. While the electrodes themselves are invisible to the CT / MRI scanner, the electrode heads are designed to be identifiable within the scan. Alternatively, the electrode positions can be measured using a camera system.

[0009] Alternatively, intracardiac mapping is used. In intracardiac mapping, potentials are measured directly in the heart muscle using electrodes, which are typically attached to a catheter or implanted. Activation times can then be calculated from these measurements. A catheter with multiple electrodes is placed in the atrium or ventricle. The electrodes then rest against the heart wall and measure the potentials against one of the other electrodes.

[0010] This is often supplemented by the automated creation of a patient-specific 3D model of the heart, which is generated during the procedure using a catheter. The catheter's position in space can be determined using magnetic fields. Finally, a 12-lead electrocardiogram (ECG) can be used in combination with a camera. The position of the electrodes is recorded by the camera. An MRI / CT scan would also be possible in principle. However, a complete map cannot be calculated with a 12-lead ECG because the electrodes are not positioned appropriately on the body.

[0011] There are also electrocardiography vests that allow for diagnoses in the traditional sense. These vests can, for example, measure ST segments across the chest to ensure more comprehensive infarction diagnostics. However, these applications are very complex and are generally only used in research.

[0012] Summary of the invention

[0013] The present invention provides methods, computer program products, devices and systems for determining a spatial distribution of a cardiac function parameter.

[0014] According to a first aspect, the present invention provides a method for determining a spatial distribution of a cardiac function parameter, wherein the spatial distribution of the cardiac function parameter comprises values ​​of the cardiac function parameter along a plurality of spatial directions.The procedure comprises the following steps: providing electrocardiographic data that allows the determination of a temporal profile of length and direction of a sum vector; determining a temporal profile for each of a multitude of components of the sum vector from the electrocardiographic data, wherein each component is assigned to one of the multitude of spatial directions; determining a multitude of values ​​of the cardiac function parameter for the multitude of spatial directions, wherein for each of the spatial directions a value of the cardiac function parameter is determined from the respective temporal profile of the assigned component of the sum vector, while preserving the spatial distribution of the cardiac function parameter.

[0015] The electric field of the heart can be represented as a superposition of electric dipoles. The electric field resulting from this superposition is, to a good approximation, itself a dipole field. The vector of the dipole moment of the electric field resulting from the superposition (i.e., the vector of the summed dipole moment) is called the sum vector. The sum vector varies in length and direction over time. Over short periods, the variation is approximately periodic, with the period corresponding to the inverse of the heart rate. In three-dimensional space, the endpoint of the sum vector traces a curve over time, also known as a vector loop.

[0016] The components of the sum vector are scalar and time-dependent quantities. For the purposes of this application, a component of the sum vector is preferably the projection of the sum vector onto the spatial direction associated with the component. However, a component of the sum vector can also be a quantity that is mathematically related to the projection of the sum vector onto the spatial direction associated with the component, preferably injectively (i.e., one value of the component does not map two different values ​​of the projection). In particular, a component of the sum vector can be a quantity that is proportional to the projection of the sum vector onto the spatial direction associated with the component.

[0017] Components that are assigned to a few, very specific spatial directions can thus correspond to the previously known, classical ECG leads (according to Einthoven, Goldberger, Wilson).

[0018] The value of the cardiac function parameter can be determined from the time course of each component along the spatial direction associated with that component. For example, the extent of ST segment elevation or depression can be determined from the time course of a component.

[0019] By determining the spatial distribution of the cardiac function parameter (along a multitude of spatial directions), a much more complete picture of cardiac function is obtained than is the case when limiting oneself to the classical leads. In particular, functional disorders or changes become visible that manifest only along a spatial direction not covered by the directions of the classical leads.

[0020] This procedure can be used particularly in connection with a pacemaker. It allows for functional testing of the pacemaker, as well as positioning and / or setting up a pacemaker, each with support for the spatial distribution of cardiac function parameters.

[0021] Furthermore, the method according to the invention is capable of real-time measurement. A measurement can be evaluated and displayed beat by beat. In contrast, with intracardiac measurements, a spatial distribution only emerges through the combination of many measurement results, which must be acquired sequentially, thus precluding real-time capability. When using an electrocardiography vest, determining a spatial distribution in real time requires considerable electronic resources for digitization and data transmission.

[0022] The method according to the invention also has the advantage that the resolution can be increased almost arbitrarily. This represents a considerable advantage, particularly compared to an electrocardiography vest, where the number of data points or directions is determined by the number of electrodes and is therefore limited by purely practical considerations, e.g., the adhesive options and the electronics for measurement.

[0023] In one variant of the procedure, the first step comprises: measuring a set of several electrical signals from several, preferably four, electrodes on the subject, wherein each of the several electrical signals originates from one of the several electrodes, while obtaining the electrocardiographic data.

[0024] The electrodes can be placed or attached, in particular, on the patient's skin.

[0025] Preferably, the four electrodes can be placed at easily identifiable locations. This increases reproducibility. Furthermore, determining the electrode positions becomes unnecessary. For example, it is not required to use a camera to capture their placement. If a CT scan is performed to project the spatial distribution onto an image of the heart, this can be done before the electrocardiography data is measured. It is not necessary to wear the electrodes during the CT scan to determine their position. Simple mapping of the electrodes onto a CT scan can be achieved, in particular, by identifying the placement or adhesive points using bones: for example, the upper end of the sternum, the lower end of the sternum, etc.In contrast, maps created with a vest can only be projected onto the CT scan if the scan itself was performed while wearing the vest, as only then is the position of the electrodes visible. Compared to using an electrocardiography vest, the procedure is significantly simplified according to the invention, and the projection can also be applied to a historical CT / MRI scan.

[0026] In a further development of this variant, the electrodes are arranged locally on the subject in such a way that the connecting lines between the electrodes represent a spatial basis.

[0027] Such an arrangement has the advantage that only four electrodes are sufficient to obtain a complete (or essentially complete) spatial distribution of the cardiac function parameter.

[0028] The use of four electrodes (especially in an arrangement where the connecting lines between the electrodes form a spatial basis) has numerous advantages over the use of an electrocardiography vest:

[0029] To diagnose a cardiac arrhythmia using an electrocardiography vest, the vest must be worn during the arrhythmia, and the CT / MRI scan must be performed with the electrodes in place. According to research, measurements and MRI scans can be performed independently, and the arrhythmia can still be visualized on the MRI scan.

[0030] Furthermore, measurements can be taken independently of complex infrastructure or medical qualifications (even by private individuals). Availability is therefore significantly higher than with an electrocardiography vest.

[0031] Furthermore, diagnostics are significantly faster than with an electrocardiography vest. Correctly applying an electrocardiography vest can take over an hour. This is particularly important for the prognosis of ischemic patients (time is muscle). Additionally, the physical strain of a measurement with an electrocardiography vest is considerably higher (especially for patients who are already severely ill or unstable).

[0032] Finally, electrocardiography vests must be manufactured in a wide variety of sizes (this is particularly problematic for female subjects or subjects with obesity). The user must therefore have many different electrocardiography vests on hand or even have a custom-made electrocardiography vest manufactured.

[0033] In comparison to intracardiac measurement, the method according to the invention has the advantage of being non-invasive.

[0034] In another variant of the method, the plurality of components comprises at least 30, preferably at least 100, more preferably at least 1000, more preferably at least 10000, more preferably at least 100000, more preferably at least 1000000 components.

[0035] In another variant of the method, the spatial distribution of the cardiac function parameter essentially covers a solid angle of TI sr, preferably 2 sr, more preferably 3 sr, more preferably 3.5K sr, more preferably 4K sr.

[0036] The limitation "substantially covers" takes into account the fact that the spatial distribution can also be discrete. Substantial coverage is preferably understood to mean a coverage of at least 30 / (4K sr), preferably at least 100 / (4K sr), more preferably at least 1000 / (4K sr), more preferably at least 100000 / (4K sr), more preferably at least 1000000 / (4K sr), components per solid angle.

[0037] Preferably, the spatial distribution of the cardiac function parameter covers a solid angle of K sr, preferably 2K sr, more preferably 3K sr, more preferably 3.5K sr, more preferably 4K sr.

[0038] In another variant of the method, the spatial resolution of the spatial distribution of the cardiac function parameter is at least so high that the angle between adjacent directions is less than 50°, preferably less than 10°, more preferably less than 5°, more preferably less than 1°, and more preferably less than 0.1°.

[0039] In another variant of the procedure, the cardiac function parameter is a temporal parameter, preferably the activation time.

[0040] If the cardiac function parameter is the activation time, it can be defined and measured according to one of the following variants (but not necessarily):

[0041] - Time of the minimum of the first lead of the signal within the QRS complex against the time of a pacemaker pulse or the position of the baseline.

[0042] - Time of the R-wave against the time of a pacemaker pulse or the position of the baseline.

[0043] In another variant of the procedure, the cardiac function parameter is a voltage parameter.

[0044] In a further development of this variant, the stress parameter is a height of an ST section, a depth of a Q wave, or a height of an R wave.

[0045] If the voltage parameter is a voltage difference, it can be determined, for example, as follows:

[0046] - Measurement of the voltage difference between the zero line and the R-wave or the ST section.

[0047] - Measurement of the voltage difference between the S-wave and the R-wave or Q-wave and the R-wave, preferably also of opposing vectors or specific areas, as this increases the diagnostic value.

[0048] If the voltage parameter is a voltage curve, it can be determined by discrete integration as follows:

[0049] - Summing of the voltage profile from one periodic feature (for example, an R-wave) to the next, summation of all spatial directions, and subsequent normalization. The stroke energy of the heart muscle can also be determined using the method according to the invention. In particular, the stroke energy can be determined by the summation described above. Ideally, this energy is constant; only the frequency changes. If the stroke energy weakens significantly with increasing frequency, this indicates a potential problem.

[0050] The cardiac function parameter can preferably be one of the following: activation time, heart rate at peak R-wave, P-wave amplitude, P-wave duration, PQ-PR duration, Q-wave amplitude, Q-wave duration

[0051] (Q WaveDuration), R-wave Amplitude (R Wave Amplitude), R-wave duration

[0052] (R WaveDuration), QR Ratio, QRS Duration, S Amplitude, ST-60N Amplitude, ST-80N Amplitude, T Amplitude, T Direction Up, QT Duration, QTc Bazett Duration, QTc Fridericia Duration, Heart Axis.

[0053] In another variant of the procedure, this also includes outputting a representation of the spatial distribution of the cardiac function parameter.

[0054] In a further development of this variant, the representation is a three-dimensional representation.

[0055] The three-dimensional representation can, in particular, be a three-dimensional representation of a spherical surface, the surface of a stylized heart, or the surface of a real heart, the latter for example captured by a computed tomography scan, wherein the value of the cardiac function parameter is indicated on the respective surface along the corresponding direction (for example by means of color coding).

[0056] The three-dimensional representation can be displayed using a two-dimensional medium, such as a screen. Preferably, user input is captured, allowing the user to rotate and / or move the representation, for example, to adopt a different perspective.

[0057] However, output via stereoscopic (e.g. virtual glasses) or holographic display is also possible.

[0058] In an alternative further education, the representation is a two-dimensional representation, in particular a map, wherein the representation preferably comprises one or more of the following: a polar diagram, a map resulting from a length-preserving map projection, a map resulting from an angle-preserving map projection, a map resulting from an area-preserving map projection, a set of several maps, each showing a part of the solid angle range covered by the spatial distribution of the cardiac function parameter.

[0059] In particular, the two-dimensional representation can be a map resulting from a Mercator projection, a Miller projection, or a Mollweide projection. Intermediate projections such as the Winkel Tripel projection can also be used. Even lobed representations, for example, resulting from a Dymaxion projection, are possible.

[0060] In another variant of the procedure, the spatial representation features a color coding for the parameter values.

[0061] The color coding assigns a color value to each value of the cardiac function parameter via a color key ("color map"). In the case of a two-dimensional representation, this representation can be, in particular, a heat map.

[0062] The color key used for color coding can be chosen, in particular, so that the representation is suitable for perception by colorblind individuals and / or for black-and-white reproduction. Specifically, the color key can be chosen so that changes in the value of the cardiac function parameter are (also) conveyed by changes in luminance / brightness. For example, the smallest value can be mapped to the darkest color value and the largest value to the brightest color value, with the transition between them preferably being monotonous. The color key is preferably uniform, such that seemingly equal differences in color and / or brightness correspond essentially equally large differences in the value of the cardiac function parameter.

[0063] The color key can optionally consist of two or more discrete color values. Specifically, a value above a threshold can be coded in a first color (e.g., red), and a value below the threshold in a second color (e.g., blue) (two-color representation). This is particularly useful when, after processing or optimization, all values ​​should be below or above the threshold (resulting in a monochromatic representation in the target state).

[0064] In another variant of the procedure, the following steps are repeated: providing electrocardiography data that allows the determination of the temporal profile of the length and direction of a sum vector; determining a temporal profile for each of a multitude of components of the sum vector from the electrocardiography data, where each component is assigned to one of the multitude of spatial directions; determining a multitude of values ​​of the cardiac function parameter for the multitude of spatial directions, whereby for each of the spatial directions, a value of the cardiac function parameter is determined from the respective temporal profile of the assigned component of the sum vector, while preserving the spatial distribution of the cardiac function parameter. In addition, this variant of the procedure includes outputting a temporal change in the representation.

[0065] By repeating the procedural steps and recording the changes over time, the development of cardiac function can be observed. In particular, improvements or deteriorations in a subject's condition can be tracked. For example, differences in cardiac function under varying stress conditions, especially at different heart rates, can also be visualized.

[0066] According to the invention, spatial distributions or representations thereof can be used to compare cardiac function parameters by subtracting them from one another or by other means. This allows, for example, the identification of trends or changes. Comparisons can be made, for instance, between spatial distributions or representations under stress and those without stress, or between historical (baseline map) and current spatial distributions or representations.

[0067] In another variant of the procedure, this also includes issuing a recommendation for action based on the spatial distribution of the cardiac function parameter.

[0068] According to another aspect, the present invention provides a computer program product. The computer program product is stored on a computer-readable medium. The computer program product comprises program code which, when executed by a computer, performs the steps of the method according to the invention.

[0069] According to a further aspect, the present invention provides a device for determining the spatial distribution of a cardiac function parameter. The device comprises a controller configured to: determine a temporal profile for each of a plurality of components of a sum vector of electrocardiographic data, wherein the electrocardiographic data allow the determination of the temporal profile of the length and direction of the sum vector, and each component is assigned to one of the plurality of spatial directions; determine a plurality of values ​​of the cardiac function parameter for the plurality of spatial directions by determining a value of the cardiac function parameter for each of the spatial directions from the respective temporal profile of the assigned component of the sum vector, while preserving the spatial distribution of the cardiac function parameter.

[0070] In one embodiment, the device includes an output device for outputting a representation of the spatial distribution of the cardiac function parameter.

[0071] According to a further aspect, the present invention provides a system for determining the spatial distribution of a cardiac function parameter. The system comprises: several, preferably four, electrodes for measuring electrical signals from the subject; a controller configured to: measure a set of the several electrical signals from the electrodes on the subject, wherein each of the several electrical signals originates from a respective electrode, thereby obtaining electrocardiographic data; determine a time course for each of a plurality of components of a sum vector from the electrocardiographic data, wherein the electrocardiographic data allow the determination of a time course of length and direction of the sum vector, and each component is assigned to one of the plurality of spatial directions.To determine a multitude of values ​​of the cardiac function parameter for the multitude of spatial directions by determining a value of the cardiac function parameter for each of the spatial directions from the respective time course of the associated component of the sum vector, while preserving the spatial distribution of the cardiac function parameter.

[0072] In one embodiment, the system includes an output device for displaying a representation of the spatial distribution of the cardiac function parameter. Preferably, the control system is configured to output a representation of the spatial distribution of the cardiac function parameter via the output device.

[0073] In another aspect, the present disclosure also relates to methods for monitoring a cardiac function parameter of a subject. The method comprises the following steps:

[0074] (a) Measuring a set of several electrical signals from several electrodes on the subject, wherein each of the several electrical signals originates from one of the several electrodes and the electrodes are spatially arranged such that the connecting lines between the electrodes form a spatial basis,

[0075] (b) Determining, based on the set of several electrical signals, a first value of a cardiac function parameter by combining the several electrical signals in the spatial basis such that the first value is assigned to a first spatial direction,

[0076] (c) Repeat step (b) for a variety of combinations of the electrical signals, so that a variety of values ​​of the cardiac function parameter are obtained, each of which is assigned to a different spatial direction.

[0077] In a preferred embodiment, the combination of the multiple electrical signals is a linear combination of potential differences.

[0078] Furthermore, the respective spatial directions can preferably be derived from the weightings of the corresponding linear combinations and the spatial basis. To determine and display a temporal change in the spatial representation, the method can further include a repetition of steps (a) to (c) and an output of the temporal change.

[0079] Furthermore, the preferred embodiments described above with regard to the first aspect can also be applied to this aspect.

[0080] Detailed description

[0081] They show:

[0082] Fig. 1 is an illustration of a human torso of a subject with sum vector and vector loop of the heart;

[0083] Fig. 2 is a schematic representation of the time course of components of the sum vector;

[0084] Fig. 3 is an illustration of a two-dimensional representation of the spatial distribution of a cardiac function parameter;

[0085] Fig. 4 shows a schematic representation of a variant of the inventive method for determining a spatial distribution of a cardiac function parameter;

[0086] Fig. 5 shows a schematic representation of a further variant of the inventive method for determining a spatial distribution of a cardiac function parameter;

[0087] Fig. 6 is an illustration of a human torso with multiple electrodes for measuring a set of several electrical signals while obtaining electrocardiographic data.

[0088] Fig. 7 shows a schematic representation of an embodiment of the device according to the invention for determining a spatial distribution of a cardiac function parameter;

[0089] Fig. 8 shows a schematic representation of an embodiment of the system according to the invention for determining a spatial distribution of a cardiac function parameter. In Figure 1, a human torso of a subject 1 is schematically represented with the sum vector S, i.e., the vector of the summed dipole moment of the electric field of the heart of subject 1. The sum vector S varies in length and direction over time and traverses a curve in three-dimensional space, which is referred to as the vector loop V.

[0090] Also shown is a component K of the sum vector S. A spatial direction n is assigned to component K. In the example shown, component K is the projection of the sum vector onto the spatial direction n.

[0091] Figure 2 schematically depicts the time histories Zx,x of 17 x 14 components K of the sum vector S. For clarity, only the time histories Zi,i, Zi7,i4, and Zijo of selected components K are labeled with reference symbols. The direction of time for each component K is indicated by an arrow 3. The gray circles correspond to previously known derivatives. For clarity, only some of the derivatives are explicitly labeled, namely derivatives VI, aVr, aVR, and II.

[0092] Figure 3 shows a two-dimensional representation 5 of the spatial distribution 7 of a cardiac function parameter t, which was determined from measured electrocardiographic data using the inventive method. In the example shown, the cardiac function parameter t is the activation time. Furthermore, the two-dimensional representation 5 is, by way of example, a map resulting from a Mercator projection. Alternatively, other projections or three-dimensional representations are also possible. The spatial distribution 7 here includes, by way of example, values ​​of the cardiac function parameter t for more than 22,000 directions.

[0093] The spatial representation shown here uses color coding as an example. A color key 9 is used for this color coding. The spatial distribution 7 in the example shown is discrete, i.e., a set of points 11 (where, for clarity, only two of the points are labeled with a reference symbol). Each point 11 corresponds to the value of the cardiac function parameter t for a spatial direction n, where the value was determined from the time course Zx,x of the associated component K of the sum vector S. The cardiac function parameter t, in the form of the activation time, varies here, for example, between 0 ms and 250 ms. Individual spatial directions n correspond to known derivatives (VI, V2, V3, V4, V5, V6, V7, V8, V9, VR3, VR4, VR5, VR6, VR7, VR8, VR9), which are labeled accordingly.

[0094] Figure 4 schematically illustrates a variant of the inventive method for determining a spatial distribution 7 of a cardiac function parameter t. The spatial distribution 7 of the cardiac function parameter t comprises values ​​of the cardiac function parameter t along a plurality of spatial directions n.

[0095] The procedure comprises the following steps: providing 13 electrocardiography data 15 that allow the determination of a temporal course of length and direction of a sum vector S; determining 17 a temporal course Zx,x for each of a plurality of components K of the sum vector S from the electrocardiography data 15, wherein each component K is assigned to one of the plurality of spatial directions n; determining 19 a plurality of values ​​of the cardiac function parameter t for the plurality of spatial directions n, wherein for each of the spatial directions n a value of the cardiac function parameter t is determined from the respective temporal course Zx,x of the assigned component K of the sum vector S, while preserving the spatial distribution 7 of the cardiac function parameter t.

[0096] Figure 5 schematically illustrates another variant of the method according to the invention. Compared to the method shown in Figure 4, the method shown in Figure 5 additionally includes the following step prior to the aforementioned process steps 13, 17, and 19: measurement 21 of a set of several electrical signals from several, preferably four, electrodes on the subject, wherein each of the several electrical signals originates from one of the respective electrodes, while obtaining the electrocardiographic data 15. For a further description, reference is made to the description of Figure 4.

[0097] Figure 6 shows three views of a human torso of a subject 1 with four electrodes El, E2, E3, E4, one each being attached at the upper end of the sternum (electrode El), at the lower end of the sternum (electrode E2), at the right mid-axillary line at the level of the lower sternal border (corresponding to the level of electrode E2) (electrode E3), and at the left mid-axillary line at the level of the lower sternal border (corresponding to the level of electrode E2) (electrode E4). Other sensor arrangements for measuring a set of several electrical signals to obtain electrocardiographic data 15, for example, ten electrodes, are known and can also be used for the purposes of the present invention. The electrodes El, E2, E3, E4 can, for example, be designed as disposable adhesive electrodes and comprise a wet or dry gel.

[0098] Such an arrangement represents an example of an arrangement at easily identifiable positions.

[0099] In the example shown, the electrodes El, E2, E3, E4 were arranged on the subject in such a way that the connecting lines between the electrodes El, E2, E3, E4 represent a spatial basis (i.e., are linearly independent).

[0100] Preferably, electrical signals in the form of three voltages (SR, SM, SL) are detected using electrodes El, E2, E3, E4. Specifically, these can be the voltage (SR) between electrode E3 and electrode El, the voltage (SM) between electrode E2 and electrode El, and the voltage (SL) between electrode E4 and electrode El. The time course of these three voltages (SR, SM, SL) determines the time course of the length and direction of the sum vector S.

[0101] As mentioned above, electrodes El, E2, E3, and E4 are each positioned at specific locations on the torso defined by the subject's bones. This allows an electrode-based measurement (for example, determining the spatial distribution of a cardiac function parameter according to the present invention) to be correlated with an imaging technique (for example, a computed tomography scan, which shows, for instance, the positions of both the heart and the aforementioned bones), even if the electrodes are not attached to the subject during the imaging measurement. This also allows an imaging measurement taken at a different time (e.g., a historical or future one) to be correlated with the electrode-based measurement.

[0102] Figure 7 shows an exemplary embodiment of the device 23 according to the invention for determining a spatial distribution 7 of a cardiac function parameter t. The device 23 comprises a controller 25, which is configured to: determine a temporal profile Zx,x for each of a plurality of components K of a sum vector S from electrocardiographic data 15, wherein the electrocardiographic data 15 allow the determination of a temporal profile of length and direction of the sum vector S and each component K is assigned to one of the plurality of spatial directions n; determine a plurality of values ​​of the cardiac function parameter t for the plurality of spatial directions n by determining a value of the cardiac function parameter t for each of the spatial directions n from the respective temporal profile Zx,x of the assigned component K of the sum vector S, while preserving the spatial distribution 7 of the cardiac function parameter t.

[0103] By way of example, but not necessarily, the device 23 includes an output device 27 for outputting a representation 5 of the spatial distribution 7 of the cardiac function parameter t, wherein in the example shown the output device 27 is a screen.

[0104] Figure 8 shows an exemplary embodiment of the system 29 according to the invention for determining a spatial distribution 7 of a cardiac function parameter t.

[0105] System 29 includes, for example, four electrodes El, E2, E3, E4 for measuring electrical signals on a subject 1. The use of a different number of electrodes is possible. A relatively small number of electrodes can be advantageous to facilitate application to the subject and minimize potential sources of error. The system also includes a controller 25.

[0106] In the example shown, electrodes El, E2, E3, E4 and the controller 25 are connected to each other by cable 31. In other embodiments, a wireless connection (e.g., Bluetooth) can be used alternatively or additionally. This can be advantageous for maintaining sterile conditions on the subject 1.

[0107] The control unit 25 is configured to: measure a set of the multiple electrical signals of the electrodes El, E2, E3, E4 on the subject 1, wherein each of the multiple electrical signals originates from one of the multiple electrodes El, E2, E3, E4, thereby obtaining electrocardiographic data 15; determine a temporal profile Zx,x for each of a plurality of components K of a sum vector S from the electrocardiographic data 15, wherein the electrocardiographic data 15 allow the determination of a temporal profile of length and direction of the sum vector S and each component K is assigned to one of the plurality of spatial directions n;To determine a multitude of values ​​of the cardiac function parameter t for the multitude of spatial directions n by determining a value of the cardiac function parameter t for each of the spatial directions n from the respective time course Zx,x of the associated component K of the sum vector S, while preserving the spatial distribution 7 of the cardiac function parameter t.;

[0108] By way of example, but not necessarily, system 29 includes an output device 27 for displaying a representation 5 of the spatial distribution 7 of the cardiac function parameter t, where in the example shown, the output device 27 is a screen. Furthermore, the controller 25 is also configured by way of example to display a representation 5 of the spatial distribution 7 of the cardiac function parameter t by means of the output device 27.

Claims

Claims 1. A method for determining the spatial distribution of a cardiac function parameter, the spatial distribution of the cardiac function parameter comprising values ​​of the cardiac function parameter along a multitude of spatial directions, comprising the steps: Provision of electrocardiography data that allows the determination of a temporal course of length and direction of a sum vector; determination of a temporal course for each of a multitude of components of the sum vector from the electrocardiography data, wherein each component is assigned to one of the multitude of spatial directions; Determination of a multitude of values ​​of the cardiac function parameter for the multitude of spatial directions, wherein for each of the spatial directions a value of the cardiac function parameter is determined from the respective temporal course of the associated component of the sum vector, while preserving the spatial distribution of the cardiac function parameter.

2. The method of claim 1, further comprising as a first step: Measurement of a set of several electrical signals from several, preferably four, electrodes on the subject, wherein each of the several electrical signals originates from one of the several electrodes, obtaining the electrocardiographic data.

3. Method according to claim 2, characterized in that the electrodes are arranged locally on the subject such that the connecting lines between the electrodes form a spatial basis.

4. Method according to one of claims 1 to 3, characterized in that the plurality of components comprises at least 30, preferably at least 100, more preferably at least 1000, more preferably at least 10000, more preferably at least 100000, more preferably at least 1000000 components.

5. Method according to any one of claims 1 to 4, characterized in that the spatial distribution of the cardiac function parameter essentially follows a solid angle of TI sr, preferably covers 2 sr, further preferably 3K sr, further preferably 3.5K sr, further preferably 4K sr.

6. Method according to one of claims 1 to 5, characterized in that the spatial resolution of the spatial distribution of the cardiac function parameter is at least so high that the angle between adjacent directions is less than 50°, preferably less than 10°, more preferably less than 5°, more preferably less than 1°, more preferably less than 0.1°.

7. Method according to one of claims 1 to 6, characterized in that the cardiac function parameter is a temporal parameter, preferably the activation time, more preferably the propagation speed, and more preferably the refractory period.

8. Method according to one of claims 1 to 6 characterized in that the cardiac function parameter is a voltage parameter, wherein preferably the voltage parameter is determined by summing the voltage profile from one periodic property to the next, wherein optionally summation over all spatial directions is also performed and subsequently normalization.

9. Method according to claim 8, characterized in that the stress parameter is a height of an ST section, a depth of a Q peak or a height of an R peak.

10. Method according to any one of claims 1 to 9, further comprising outputting a representation of the spatial distribution of the cardiac function parameter.

11. Method according to claim 10, characterized in that the representation is a three-dimensional representation.

12. The method of claim 10, characterized in that the representation is a two-dimensional representation, in particular a map, wherein the representation preferably comprises one or more of the following: a polar diagram, a map resulting from a length-preserving map projection, a map resulting from an angle-preserving map projection, a map resulting from an area-preserving map projection, a set of several maps, each representing a part of the area represented by the spatial distribution of the cardiac function parameter covered solid angle range.

13. Method according to one of claims 10 to 12, wherein the spatial representation has a color coding for the values ​​of the parameter.

14. Method according to any one of claims 10 to 13, further comprising a repetition of the method steps according to claim 1 and an output of a temporal change of the representation.

15. Method according to any one of claims 1 to 14, further comprising outputting a recommendation for action based on the spatial distribution of the cardiac function parameter.

16. Computer program product stored on a computer-readable medium and comprising program code which, when executed by a computer, performs the steps of the method defined in any one of claims 1 to 15.

17. Device for determining a spatial distribution of a cardiac function parameter, comprising a control unit configured to To determine a temporal profile for each of a plurality of components of a sum vector of electrocardiographic data, wherein the electrocardiographic data allow the determination of a temporal profile of length and direction of the sum vector and each component is assigned to one of the plurality of spatial directions; To determine a multitude of values ​​of the cardiac function parameter for the multitude of spatial directions by determining a value of the cardiac function parameter for each of the spatial directions from the respective temporal course of the associated component of the sum vector, while preserving the spatial distribution of the cardiac function parameter.

18. System for determining a spatial distribution of a cardiac function parameter, comprising: Several, preferably four, electrodes for measuring electrical signals in a subject; Control system configured to: o Measure a set of several electrical signals from the electrodes on the subject, wherein each of the several electrical signals originates from one of the several electrodes, while obtaining electrocardiography data; o Determine a time course for each of a plurality of components of a sum vector from the electrocardiography data, wherein the electrocardiography data allow the determination of a time course of length and direction of the sum vector and each component is assigned to one of the plurality of spatial directions; o Determine a plurality of values ​​of the cardiac function parameter for the plurality of spatial directions by determining a value of the cardiac function parameter for each of the spatial directions from the respective time course of the assigned component of the sum vector, while preserving the spatial distribution of the cardiac function parameter. TI

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