Accurate time annotation of intracardiac ECG signals

1. A method for analyzing signals, comprising:

sensing a time-varying intracardiac potential signal;

finding a fit of the time-varying intracardiac potential signal to a predefined oscillating waveform; and

estimating a reference time of occurrence of a characteristic of the signal responsive to the fit,

wherein the time-varying intracardiac potential signal comprises a bipolar signal, and

the predefined oscillating waveform comprises a difference between a first single complete oscillation and a second single complete oscillation.

2. The method according to claim 1 , wherein the first single complete oscillation comprises a first single local maximum, a first single local minimum, and a first inflection separating the first local maximum and minimum, and wherein the second single complete oscillation comprises a second single local maximum, a second single local minimum, and a second inflection separating the second local maximum and minimum.

3. The method according to claim 1 , wherein the first single complete oscillation and the second complete oscillation are separated by a temporal difference.

4. The method according to claim 3 , wherein the temporal difference is a function of a spatial separation of electrodes generating the bipolar signal.

5. The method according to claim 3 , wherein the temporal difference is a function of an electrode orientation relative to a propagation direction of an activation wave.

6. A method for analyzing signals, comprising:

sensing a time-varying intracardiac potential signal;

finding a fit of the time-varying intracardiac potential signal to a predefined oscillating waveform; and

estimating a reference time of occurrence of a characteristic of the signal responsive to the fit,

wherein the time-varying intracardiac potential signal comprises a bipolar signal, and

the predefined oscillating waveform comprises a difference between a first Gaussian function first differential and a second Gaussian function first differential.

7. The method according to claim 6 , wherein the first Gaussian function first differential is skewed by a first asymmetry factor and the second Gaussian function first differential is skewed by a second asymmetry factor.

8. A method for analyzing signals, comprising:

sensing a time-varying intracardiac potential signal;

finding a fit of the time-varying intracardiac potential signal to a predefined oscillating waveform; and

estimating a reference time of occurrence of a characteristic of the signal responsive to the fit,

wherein the time-varying intracardiac potential signal comprises three or more unipolar signals having temporal differences therebetween, and wherein a propagation direction of an activation wave is a function of the temporal differences.

9. The method according to claim 8 , wherein respective electrodes having respective positions generate the three or more unipolar signals, and wherein the respective positions comprise parameters of the function.

10. Apparatus for analyzing signals, comprising:

a sensor configured to sense a time-varying intracardiac potential signal; and

a processor configured to:

find a fit of the time-varying intracardiac potential signal to a predefined oscillating waveform, and estimate a reference times of occurrence of a characteristic of the signal responsive to the fit,

wherein the time-varying intracardiac potential signal comprises a bipolar signal, and

the predefined oscillating waveform comprises a difference between a first single complete oscillation and a second single complete oscillation.

11. The apparatus according to claim 10 , wherein the first single complete oscillation comprises a first single local maximum, a first single local minimum, and a first inflection separating the first local maximum and minimum, and wherein the second single complete oscillation comprises a second single local maximum, a second single local minimum, and a second inflection separating the second local maximum and minimum.

12. The apparatus according to claim 10 , wherein the first single complete oscillation and the second complete oscillation are separated by a temporal difference.

13. The apparatus according to claim 12 , wherein the temporal difference is a function of a spatial separation of electrodes generating the bipolar signal.

14. The apparatus according to claim 12 , wherein the temporal difference is a function of an electrode orientation relative to a propagation direction of an activation wave.

15. An apparatus for analyzing signals, comprising:

a sensor configured to sense a time-varying intracardiac potential signal; and

a processor configured to:

find a fit of the time-varying intracardiac potential signal to a predefined oscillating waveform, and estimate a reference times of occurrence of a characteristic of the signal responsive to the fit,

wherein the time-varying intracardiac potential signal comprises a bipolar signal, and

wherein the predefined oscillating waveform comprises a difference between a first Gaussian function first differential and a second Gaussian function first differential.

16. The apparatus according to claim 15 , wherein the first Gaussian function first differential is skewed by a first asymmetry factor and the second Gaussian function first differential is skewed by a second asymmetry factor.

17. An apparatus for analyzing signals, comprising:

a sensor configured to sense a time-varying intracardiac potential signal; and

a processor configured to:

find a fit of the time-varying intracardiac potential signal to a predefined oscillating waveform, and estimate a reference times of occurrence of a characteristic of the signal responsive to the fit,

wherein the time-varying intracardiac potential signal comprises three or more unipolar signals having temporal differences therebetween, and wherein a propagation direction of an activation wave is a function of the temporal differences.

18. The apparatus according to claim 17 , wherein respective electrodes having respective positions generate the three or more unipolar signals, and wherein the respective positions comprise parameters of the function.