Device for identifying the site of cardiac arrhythmias

Abstract

The device for locating cardiac arrhythmias comprises a three-dimensional reconstruction of the patient's torso and a number of surface electrodes, wherein the three-dimensional reconstruction of the patient's torso is generated through a number of images obtained by means of at least one camera. In particular, the device comprises elements for locating the surface electrodes, which detect the position of the electrodes with respect to the patient's torso, and data processing elements that generate, on the basis of the three-dimensional reconstruction and the position of the electrodes, a surface electrocardiographic map, and said surface electrocardiographic map has a number of data corresponding to readings of the surface electrodes related to areas of the three-dimensional reconstruction.

Claims

1. A device for locating and detecting the cardiac regions responsible for irregular cardiac arrhythmias, the device comprising: a three-dimensional reconstruction element that generates a three-dimensional reconstruction of a surface of a patient's torso through processing a plurality of images, including a number of images of the surface of the patient's torso obtained by at least one camera, wherein at least one camera is a visible imaging camera, wherein the number of images is at least two and wherein images are taken from different positions; image analysis element for locating a plurality of surface electrodes, wherein the plurality of surface electrodes are positioned on the patient's torso and whereby the image analysis element detects the position of the electrodes with respect to the surface of the patient's torso, wherein the image analysis element detects the position of the electrodes by processing the images with which the three-dimensional reconstruction of the patient's torso is performed; data processing elements that correlate a number of readings of the surface electrodes to the three-dimensional reconstruction and the position of the surface electrodes to generate a surface electrocardiographic map, and a display for receiving and displaying the surface electrocardiographic map.

2. The device of claim 1, further comprising an angiographic camera.

3. The device of claim 1, wherein the device comprises processing elements for locating the area of the torso that presents a cardiac arrhythmia.

4. The device of claim 1, comprising at least one intracavity catheter having at least one electrode that takes intracavity readings.

5. The device of claim 4, comprising elements for locating intracavity catheters.

6. The device of claim 5, comprising elements for generating an intracavity anatomical reconstruction on the basis of the intracavity readings and the elements for locating the intracavity catheters.

7. The device of claim 6, wherein, by correlating the data from the intracavity anatomical reconstruction and the surface electrocardiographic map, the processing elements generate an electroanatomical map wherein the electrical activity of each area is identified.

8. The device of claim 7, comprising elements for detecting cardiac arrhythmias in the electroanatomical map.

9. The device of claim 6 further comprising a processor receiving information from the intracavity readings and the surface electrocardiographic map and performing an iterative estimation of a transfer matrix between a plurality of atrial epicardium potentials (U.sub.A) and torso potentials (U.sub.T) using an equation: MU.sub.A=U.sub.T.

10. The device of claim 9, wherein performing the iterative estimation further comprises solving the following equation:
min{|MU.sub.A(λ)−U.sub.T∥.sup.2+λ∥BU.sub.A(λ)∥.sup.2} Where λ is a regularization parameter and B is a spatial regularization matrix.

Description

DESCRIPTION OF THE DRAWINGS

(1) In order to supplement the description being made, and to contribute to a better understanding of the characteristics of the invention, according to a preferred embodiment thereof, a set of drawings is attached to said description as an integral part thereof, where the following is represented for illustrative, non-limiting purposes:

(2) FIG. 1.—Shows a schematic view of the device for detecting cardiac arrhythmias according to the present invention, as well as the detection method.

PREFERRED EMBODIMENT OF THE INVENTION

(3) FIG. 1 shows a preferred embodiment of the present invention. In this embodiment, it may be observed that the device essentially involves taking three measurements.

(4) The first measurement involves performing a three-dimensional reconstruction (4) of the patient's torso by means of a set of images (1), for example, two-dimensional images obtained by means of a camera. This reconstruction is performed by means of at least two photographs taken using image processing techniques that are widely known in the prior art.

(5) The second measurement is a surface electrocardiographic map. This map is performed by taking data from a number of surface electrodes (2) and associating the data taken from said electrodes with a particular area of the patient's body. The data obtained by means of said electrodes are a number of electrical signals (5) obtained non-invasively (without any surgical procedure whatsoever). Moreover, as mentioned above, it is important to find a correlation between the electrical signals (5) and the position of the electrode that has taken each of the signals, in order to determine to which part of the heart each signal corresponds.

(6) Consequently, the present invention considers elements for detecting the position of the electrodes. This detection of the position of the electrodes is most preferably performed by means of image analysis, in particular, analysis of the images (1) with which the three-dimensional reconstruction (4) of the patient's torso is performed, or, alternatively, of other images obtained using the same elements for obtaining images. On the basis of this detection, a correlation between the electrical data and the position of the electrodes with respect to the patient's body may be performed, i.e. we may obtain a three-dimensional reconstruction (4) of the patient's torso, the position of the electrodes on the torso and the electrical signals measured for each of the points of the torso, and, with these data, obtain a surface electrical map that is nothing less than the combination of all these data into a graphic representation.

(7) Although on the basis of these data we could already have a three-dimensional representation of the functioning of each of the areas of the heart and locate cardiac arrhythmias, the present invention considers that, in order to increase the accuracy in locating the area wherein said arrhythmias appear, intracavity records may be taken (3) by using at least one catheter. Although this process is intrusive, it requires less intrusion than the mapping processes in the prior art.

(8) Basically, for this measurement, there is a catheter inside the heart that sequentially measures the activity at various points in the atrium. The position of this catheter at each moment may be determined using elements for detecting the position of the catheter (for example, using two-dimensional photographs of the type used to perform the three-dimensional reconstruction (4)). Once the activity has been measured at several points and recorded in several intracavity records (3), we may obtain an intracavity anatomical reconstruction (6), which may be used for the reconstruction of the epicardium (i.e. an intracavity anatomical reconstruction) on the basis of the non-invasive records, using a regularisation of the solution of the inverse problem (8) based on quadratic and non-quadratic stabilisation functions under spatio-temporal discontinuity conditions. In this way, the signals calculated on the basis of the non-invasive records are used for the representation of the epicardial electroanatomical maps (11).

(9) It is worth mentioning that the intracavity mapping (3) is not essential for the system to calculate the epicardial potentials, which are calculated on the basis of the non-invasive surface records by solving the inverse problem, but using a few intracavity points is very helpful for a reliable reconstruction of the mathematical problem, which guarantees reliability even during irregular arrhythmias, such as atrial fibrillation.

(10) Once the activity has been measured at several intracavity points (3), we may obtain an intracavity anatomical reconstruction (6), which may be used for the reconstruction of the epicardium on the basis of the non-invasive records, by using a regularisation of the solution of the inverse problem based on quadratic and non-quadratic stabilisation functions under spatio-temporal discontinuity conditions, i.e. an electroanatomical correlation (8) is made taking into consideration the data obtained by means of the surface electrocardiographic map (7) and the intracavity anatomical reconstruction (6).

(11) Specifically, the solution of the inverse problem is performed by means of the iterative estimation of the transfer matrix between the potentials in the atrial epicardium (U.sub.A) and the potentials on the torso (U.sub.T):
MU.sub.A=U.sub.T

(12) This is an ill-conditioned problem, since the number of estimated points on the surface of the epicardium (e.g. 2000 epicardial points) is much larger than the number of potentials on the torso (e.g. 120 electrodes on the torso). For this reason, calculation of the inverse transfer matrix is performed by minimising the error according to the following equation:
min{|MU.sub.A(λ)−U.sub.T∥.sup.2+λ∥BU.sub.A(λ)∥.sup.2}

(13) where λ is a regularisation parameter and B is the spatial regularisation matrix. Calculation of the optimal transfer matrix M is performed by means of the iterative solution of the problem for various temporal and spatial regularisation values, in order to ensure an appropriate representation of the power distribution within the frequency spectrum.

(14) In addition to what has been discussed above, the intracavity electrical signals (10) obtained by means of the intracavity catheter may be taken as an anchor and validation point for the reconstruction of the entire epicardial map on the basis of the non-invasive signals, in order to perform a stabilisation (9) of the inverse problem through the spatio-temporal correlation of the intracavity recording points according to the time, phase, modulus, spectrum and causality information. This makes it possible to reconstruct the activity of the entire atrium in a quick, reliable manner, even during irregular arrhythmias, such as atrial fibrillation.