METHOD AND SYSTEM FOR MEASURING CARDIAC ELECTROGRAM DEPOLARIZATION VOLTAGE
A system and a method for determining cardiac tissue health based on a depolarization wave within an electrogram (EGM) is disclosed. The method comprises selecting a portion of a depolarization wave demarcated by a start time and end time and computing a Peak-to-Peak (P2P) voltage for the electrogram by computing a difference in voltages of the EGM corresponding to the start time and the end time.
1 . A method for determining cardiac tissue health based on a depolarization wave within an electrogram (EGM), the method comprising:
receiving the EGM of a user;
extracting a portion of the depolarization wave from the received EGM;
determining a local activation time (LAT), wherein determining the LAT comprises:
determining a minimum value and a maximum value of a first derivative wave of the EGM;
calculating a ratio by dividing a magnitude of the minimum value by the maximum value;
comparing the ratio with at least a threshold value; and
determining the LAT based on an outcome of the comparison;
determining a start time of the depolarization wave;
determining an end time of the depolarization wave;
computing a Peak-to-Peak (P2P) voltage for the EGM by computing a difference in voltages of the EGM at the start time and the end time; and
outputting the computed P2P voltage and the determined LAT for determining the cardiac tissue health of the user.
2 . The method of claim 1 , wherein comparing the ratio with the at least a threshold value comprises determining if the ratio is above a first threshold, below a second threshold, or in between the first threshold and the second threshold.
3 . The method of claim 1 , wherein:
the EGM comprises a unipolar EGM; and
determining the LAT further comprises setting the LAT as a time associated with the minimum value of the first derivative wave.
4 . The method of claim 3 , wherein:
determining the start time comprises setting the start time based on a first inflection point of the EGM immediately before the LAT; and
determining the end time of comprises setting the end time based on a second inflection point of the EGM immediately after the LAT.
5 . The method of claim 1 , wherein:
the EGM comprises a bipolar EGM; and
determining the LAT comprises averaging a first time and a second time, wherein the first time is associated with the minimum value and the second time is associated with the maximum value.
6 . The method of claim 1 , wherein determining the start time comprises determining the start time by searching backwards relative to the LAT.
7 . The method of claim 6 , wherein searching backwards relative to the LAT comprises:
searching through the EGM as a function of conditions comprising the first derivative wave having a value greater than zero, a presence of a first peak in the first derivative wave, and a presence of a second peak in the EGM; and
setting the start time as a time at which any one of the conditions is first met.
8 . The method of claim 1 , wherein determining the end time comprises determining the end time by searching forwards relative to the LAT.
9 . The method of claim 8 , wherein searching forwards relative to the LAT comprises:
searching through the EGM as a function of conditions comprising the first derivative wave having a value greater than zero, a presence of a first nadir in the first derivative wave, and a presence of a second nadir in the EGM; and
setting the end time as a time at which any one of the conditions is first met.
10 . A system for determining cardiac tissue health based on a depolarization wave within an electrogram (EGM), the system comprising:
one or more processors; and
a memory coupled to one or more processors, wherein the memory is programmed with executable instructions configuring the one or more processors to:
receive an EGM of a user;
extract a portion of a depolarization wave from the received EGM;
determine a local activation time (LAT), wherein determining the LAT comprises:
determining a minimum value and a maximum value in a first derivative wave of the EGM;
calculating a ratio by dividing a magnitude of the minimum value by the maximum value;
comparing the ratio with at least a threshold value; and
determining the LAT based on an outcome of the comparison;
determine a start time of the depolarization wave;
determine an end time of the depolarization wave;
compute a P2P voltage for the EGM by computing a difference in voltages of the EGM corresponding to the start time and the end time; and
output the computed P2P voltage and the determined LAT to determine the cardiac tissue health of the user.
11 . The system of claim 10 , wherein comparing the ratio with the at least a threshold value comprises determining if the ratio is above a first threshold, below a second threshold, or in between the first threshold and the second threshold.
12 . The system of claim 10 , wherein:
the EGM comprises a unipolar EGM; and
determining the LAT further comprises setting the LAT as a time associated with the minimum value of the first derivative wave.
13 . The system of claim 12 , wherein:
determining the start time comprises setting the start time based on a first inflection point of the EGM immediately before the LAT; and
determining the end time of comprises setting the end time based on a second inflection point of the EGM immediately after the LAT.
14 . The system of claim 10 , wherein:
the EGM comprises a bipolar EGM; and
determining the LAT comprises averaging a first time and a second time, wherein the first time is associated with the minimum value and the second time is associated with the maximum value.
15 . The system of claim 10 , wherein determining the start time comprises determining the start time by searching backwards relative to the LAT.
16 . The system of claim 15 , wherein searching backwards relative to the LAT comprises:
searching through the EGM as a function of conditions comprising the first derivative wave having a value greater than zero, a presence of a first peak in the first derivative wave, and a presence of a second peak in the EGM; and
setting the start time as a time at which any one of the conditions is first met.
17 . The system of claim 10 , wherein determining the end time comprises determining the end time by searching forwards relative to the LAT.
18 . The system of claim 17 , wherein searching forwards relative to the LAT comprises:
searching through the EGM as a function of conditions comprising the first derivative wave having a value greater than zero, a presence of a first nadir in the first derivative wave, and a presence of a second nadir in the EGM; and
setting the end time as a time at which any one of the conditions is first met.
19 . A non-transitory computer readable storage medium, having stored thereon, a set of computer-executable instructions that configures a computer to:
receive an EGM of a user;
extract a portion of a depolarization wave from the received EGM;
determine a local activation time (LAT), wherein determining the LAT comprises:
determining a minimum value and a maximum value in a first derivative wave of the EGM;
calculating a ratio by dividing a magnitude of the minimum value by the maximum value;
comparing the ratio with at least a threshold value; and
determining the LAT based on an outcome of the comparison;
determine a start time of the depolarization wave;
determine an end time of the depolarization wave;
compute a P2P voltage for the EGM by computing a difference in voltages of the EGM corresponding to the start time and the end time; and
output the computed P2P voltage and the determined LAT to determine cardiac tissue health of the user.
20 . The non-transitory computer readable storage medium of claim 19 , wherein comparing the ratio with the at least a threshold value comprises determining if the ratio is above a first threshold, below a second threshold, or in between the first threshold and the second threshold.