RECONSTRUCTION OF A SURFACE ELECTROCARDIOGRAM BASED UPON AN ENDOCARDIAL ELECTROGRAM

• US 20080114259A1
• Filed: 09/25/2007
• Published: 05/15/2008
• Est. Priority Date: 09/25/2006
• Status: Active Grant

• Current Assignee: Sorin CRM USA (MicroPort Scientific Corp.)
• Original Assignee: Sorin CRM SAS
• Inventors: DAL MOLIN, RENZO, Carrault, Guy, Bourguiba, Anissa, Hernandez, Alfredo, Poree, Fabienne
• Granted Patent: US 8,050,749 B2
• Time in Patent Office: Days
• US Class Current: 600/523
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/327 Generation of artificial ECG signals based on measured signals, e.g. to compensate for missing leads
• CPC Class Codes: A61B 5/341 Vectorcardiography [VCG]
• CPC Class Codes: A61N 1/3702 Physiological parameters A61N1/365 takes precedence; evoked response A61N1/371
• CPC Class Codes: G06F 2218/22 Source localisation; Inverse modelling

Abstract

The reconstruction of a surface electrocardiogram based upon an endocardial electrogram. This method includes: (a) acquisition (10) of a plurality of endocardial electrogram signals (EGM) through a plurality of endocardial derivations defined based upon endocardial electrodes; (b) calculation (12), by combining the endocardial electrogram (EGM) signals acquired at step (a), of the corresponding endocardial vectogram (VGM); (c) angular resealing (14) of the orthonormated mark of the endocardial vectogram (VGM) with that of the surface vectocardiogram (VCG); (d) estimation (16), based upon the endocardial vectogram (VGM) calculated at step (b), of a reconstructed surface vectocardiogram (VCG_{reconstructed}), and (e) calculation (18) of the surface electrocardiogram (ECG) corresponding to said reconstructed surface vectocardiogram (VCG_{reconstructed}).

Claims

1. A process for processing signal'"'"'s representative of cardiac myocardium depolarization potentials, said signals being signals collected by a plurality of endocardial electrodes of an active implantable medical device such as an implantable pacemaker, device for resynchronization, cardioversion and/or defibrillation, comprising:

a) acquiring a plurality of endocardial electrogram signals (EGM) through a plurality of endocardial or intravascular derivations, defined based upon said endocardial electrodes;

b) calculating, through a combination of the endocardial electrogram signals (EGM) acquired at step a), corresponding endocardial vectogram (VGM);

d) estimating, based upon the endocardial vectogram calculated at step b), a reconstructed surface vectocardiogram (VCG_{reconstructed}); and

e) calculating surface electrocardiogram signals (ECG) corresponding to said reconstructed surface vectocardiogram (VCG_{reconstructed}).

2. The process of claim 1, wherein step b) of calculating the endocardial vectogram (VGM) further comprises performing an orthogonalization process.

3. The process of claim 2, wherein performing said orthogonalization process further comprises performing a Karhuen-Loeve transform of said combination of EGM signals.

4. The process of claim 1, further comprising, between steps b) and d):

c) angular rescaling the orthonormated mark of the endocardial vectogram (VGM) upon that of the surface vectocardiogram (VCG).

5. The process of claim 4, further comprising a preliminary step of calibration comprising determining parameters of said angular rescaling.

6. The process of claim 5, wherein determining angular rescaling parameters further comprises:

i) obtaining a set of reference data through simultaneous acquisition of endocardial electrogram signals (EGM) and surface electrocardiogram signals (ECG);

ii) calculating, through a combination of the surface electrocardiogram signals (ECG) acquired at step i), a corresponding surface vectocardiogram (VCG_real);

iii) calculating, through a combination of endocardial electrogram signals (EGM) acquired at step i), a corresponding endocardial vectogram (VGM);

iv) angular resealing the orthonormated mark of the endocardial vectogram (VGM) upon that of the surface vectocardiogram (VCG_real);

v) estimating, based upon the endocardial vectogram (VGM) calculated at step iii), of a reconstructed surface vectocardiogram (VCG_{reconstructed}); and

vi) adjusting the angular resealing parameters of step iv) so as to minimize the deviation between the surface vectocardiogram (VCG_real) calculated at step ii) and the reconstructed surface vectocardiogram (VCG_{reconstructed}) calculated at step v).

7. The process of claim 6, wherein said deviation to be minimized is the root-mean-square deviation.

8. The process of claim 6, further comprising providing an adaptive neural network for the determination of said angular resealing parameters.

9. The process of claim 1, wherein, at step d), estimating the reconstructed surface vectocardiogram (VCG_{reconstructed}) further comprises applying a non-linear filtering to the endocardial vectogram calculated at step b).

10. The process of claim 9, further comprising providing an adaptive neural network to implement said non-linear filtering.

11. The process of claim 9, further comprising a preliminary calibration step comprising determining parameters of said non-linear filtering.

12. The process of claim 11, wherein determining non-linear filtering parameters further comprises:

i) obtaining a set of reference data through simultaneous acquisition of endocardial electrogram signals (EGM) and surface electrocardiogram signals (ECG);

ii) calculating, through a combination of the surface electrocardiogram signals (ECG) acquired at step i), a corresponding surface vectocardiogram (VCG_real);

iii) calculating, through a combination of endocardial electrogram signals (EGM) acquired at step i), a corresponding endocardial vectogram (VGM);

iv) conducting a possible angular rescaling of the orthonormated mark of the endocardial vectogram (VGM) upon that of the surface vectocardiogram (VCG_real);

v) estimating, through applying non-linear filtering to the endocardial vectogram calculated at step iii), a reconstructed surface vectocardiogram (VCG_{reconstructed}); and

vi) adjusting the non-linear filtering parameters of step v) so as to minimize the deviation between the surface vectocardiogram (VCG_real) calculated at step ii) and the reconstructed surface vectocardiogram (VCG_{reconstructed}) calculated at step v).

13. The process of claim 9, further comprising providing to said non-linear filtering as an input, at least one of the parameters selected from among:

a respiratory signal, information on the position of the endocardial sensing electrodes, the P, QRS or T phase of the cardiac cycle; and

a signal representative of intracardiac impedance.

14. The process of claim 1, wherein said intracardiac derivations are defined based upon a plurality of electrodes chosen among:

right ventricular distal and/or proximal electrode, right atrial distal and/or proximal electrode, left ventricular distal and/or proximal electrode, ventricular or atrial defibrillation coil, and supra-ventricular defibrillation coil.

15. Apparatus for processing signals representative of cardiac myocardium depolarization potentials, comprising:

a) means for acquiring a plurality of endocardial electrogram signals (EGM) representative of a plurality of endocardial or intravascular derivations;

b) means for calculating, based on a combination of said acquired endocardial electrogram signals (EGM), a corresponding endocardial vectogram (VGM);

c) means for estimating, based upon the calculated endocardial vectogram, a reconstructed surface vectocardiogram (VCG_{reconstructed}); and

d) means for calculating surface electrocardiogram signals (ECG) corresponding to said reconstructed surface vectocardiogram (VCG_{reconstructed}).

16. The apparatus of claim 15, wherein said means for calculating the endocardial vectogram (VGM) further comprises means for performing an orthogonalization process.

17. The apparatus of claim 16, wherein said means for performing said orthogonalization process further comprises means for performing a Karhuen-Loeve transform of said combination of EGM signals.

18. The apparatus of claim 15, further comprising:

means for angular rescaling the orthonormated mark of the endocardial vectogram (VGM) upon that of the surface vectocardiogram (VCG) prior to estimating said reconstructed surface vectocardiogram.

19. The apparatus of claim 18, further comprising means for determining parameters of said angular rescaling during a preliminary calibration.

20. The apparatus of claim 15, wherein, the means for, estimating the reconstructed surface vectocardiogram (VCG_{reconstructed}) further comprises means for applying a non-linear filtering to the calculated endocardial vectogram, said means for nonlinear filtering further comprising a neural network.

22. The software control module of claim 20, wherein said second instruction set further comprises instructions performing an orthogonalization process by performing a Karhuen-Loeve transform of said combination of EGM signals.

23. The software control module of claim 20, further comprising:

an instruction set for angular resealing the orthonormated mark of the endocardial vectogram (VGM) upon that of the surface vectocardiogram (VCG) prior to estimating said reconstructed surface vectocardiogram.

24. The software control module of claim 18, further comprising an instruction set for determining parameters of said angular resealing during a preliminary calibration.

25. The software control module of claim 24, wherein the instruction set for determining angular resealing parameters further comprise instructions for:

i) obtaining a set of reference data through simultaneous acquisition of endocardial electrogram signals (EGM) and surface electrocardiogram signals (ECG);

ii) calculating, through a combination of the surface electrocardiogram signals (ECG) acquired at step i), a corresponding surface vectocardiogram (VCG_real);

iii) calculating, through a combination of endocardial electrogram signals (EGM) acquired at step i), a corresponding endocardial vectogram (VGM);

iv) angular resealing the orthonormated mark of the endocardial vectogram (VGM) upon that of the surface vectocardiogram (VCG_real);

v) estimating, based upon the endocardial vectogram (VGM) calculated at step iii), of a reconstructed surface vectocardiogram (VCG_{reconstructed}); and

vi) adjusting the angular resealing parameters of step iv) so as to minimize the deviation between the surface vectocardiogram (VCG_real) calculated at step ii) and the reconstructed surface vectocardiogram (VCG_{reconstructed}) calculated at step v).

21. A software control module for processing signals representative of cardiac myocardium depolarization potentials, comprising:

a) a first instruction set for acquiring a plurality of endocardial electrogram signals (EGM) representative of a plurality of endocardial or intravascular derivations;

b) a second instruction set for calculating, based on a combination of said acquired endocardial electrogram signals (EGM), a corresponding endocardial vectogram (VGM);

c) a third instruction set for estimating, based upon the calculated endocardial vectogram, a reconstructed surface vectocardiogram (VCG_{reconstructed}); and

d) a fourth instrtuction set for calculating surface electrocardiogram signals (ECG) corresponding to said reconstructed surface vectocardiogram (VCG_{reconstructed}).