Identifying ambiguous cardiac signals for electrophysiologic mapping

1. A system for use in cardiac monitoring, comprising:

an electrode apparatus comprising a plurality of electrodes configured to be located proximate tissue of a patient and to provide signals each corresponding to one of a plurality of channels;

a display apparatus comprising a graphical user interface, wherein the graphical user interface is configured to present information corresponding to one or more of the plurality of channels;

computing apparatus coupled to the electrode apparatus and display apparatus, wherein the computing apparatus is configured to determine a maximum for each beat of one of the signals corresponding to one of the plurality of channels, the one of the signals comprising a plurality of time-indexed samples, wherein, to determine the maximum for each of the beats, the computing apparatus is configured to:

calculate a square of a first derivative and a maximum of the square of the first derivative of the one of the signals;

analyze the one of the signals to identify at least ones of the time indexed samples of the one of the signals where the square of the first derivative is greater than a ratio value (R) times the maximum of the square of the first derivative (M 2 );

in response to the one of the signals having been analyzed, calculate a second derivative of the one of the signals;

determine local maximums of the the one of the signals using the second derivative;

determine an index difference between an index of a first local maximum of the local maximums and an index of a second local maximum of the local maximums and determine if the index difference is greater than a first preselected number or less than a second preselected number;

in response to the index difference being less than the first preselected number and greater than the second preselected number, determine a maximum for each of the beats; and

in response to the index difference being greater than the first preselected number or less than the second preselected number, modify the R resulting in a modified R.

2. The system of claim 1 , wherein the index difference being greater than the first preselected number indicates a beat was missed.

3. The system of claim 2 , wherein, in response to the indication that there is a missed beat, decreasing the R to result in the modified R.

4. The system of claim 1 , wherein the index difference being less than the second preselected number indicates data between at least two beats are artifacts.

5. The system of claim 4 , wherein, in response to the indication that the data between at least two beats are artifacts, increasing the R to result in the modified R.

6. The system of claim 1 , wherein the first preselected number is greater than the second preselected number.

7. A method for use in cardiac monitoring, comprising:

providing an electrode apparatus configured to provide signals each corresponding to one of a plurality of channels and locating the electrode apparatus proximate tissue of a patient;

acquiring the signals using the electrode apparatus, wherein each of the signals comprises a plurality of time indexed samples;

channels,

determining a maximum for each beat of one of the signals corresponding to one of the plurality of channels, wherein determining a maximum for each beat of the signal comprises:

calculating a square of a first derivative and a maximum of the square of the first derivative of the one of the signals;

analyzing the one of the signals to identify ones of the time indexed samples of the one of the signals where the square of the first derivative is greater than a ratio value (R) times the maximum of the square of the first derivative (M 2 );

in response to the one of the signals having been analyzed, calculating a second derivative of the one of the signals;

determining local maximums of the one of the signals using the second derivative;

determining an index difference between an index of a first local maximum and an index of a second local maximum of the local maximums and determining if the index difference is greater than a first preselected number or less than a second preselected number;

in response to the index difference being less than the first preselected number and greater than the second preselected number, determining a maximum for each of the beats; and

in response to the index difference being greater than the first preselected number or less than the second preselected number, modify the R resulting in a modified R.

8. The method of claim 7 , wherein the index difference being greater than the first preselected number indicates a beat was missed.

9. The method of claim 8 , wherein, in response to the indication that there is a missed beat, decreasing the R to result in the modified R.

10. The method of claim 7 , wherein the index difference being less than the second preselected number indicates data between at least two beats are artifacts.

11. The method of claim 10 , wherein, in response to the indication that the data between at least two beats are artifacts, increasing the R to result in the modified R.

12. The method of claim 7 , wherein the first preselected number is greater than the second preselected number.

13. The method of claim 7 , wherein the electrode apparatus is located around the patient's torso.

14. The method of claim 7 , wherein the signal is acquired from a patient diagnosed with atrial fibrillation.

15. The method of claim 7 , wherein the method is used to locate optimal electrode placement for cardiac therapy.