Apparatus and method for collecting data useful for determining the parameters of an alert window for timing delivery of ETC signals to a heart under varying cardiac conditions
First Claim
1. A method for obtaining from a patient'"'"'s heart data useful for on-line determining of the parameters of an alert time window in an excitable tissue control device, the method comprising the steps of:
- Applying electrodes to a first cardiac site and a second cardiac site of said patient and electrically connecting said electrodes to a data collecting device;
Operating said device under a plurality of different cardiac conditions to obtain a plurality of different histogram data sets, each histogram data set of said plurality of histogram data sets represents a cumulative time distribution histogram of cardiac depolarization events detected at said second cardiac site in a plurality of cardiac beats, each histogram data set of said plurality of histogram data sets is associated with a plurality of histogram parameters, said histogram parameters have values indicative of the cardiac conditions common to said plurality of cardiac beats used to obtain said histogram data set, said histogram parameters include a sensitivity level parameter having a value indicative of the detection sensitivity level used for detecting said cardiac depolarization events of said plurality of cardiac beats at said second cardiac site; and
Processing said plurality of histogram data sets to compute a set of data usable for on-line determination of the parameters of said alert time window.
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Abstract
Apparatus and method for obtaining from a patient'"'"'s heart data useful for on-line setting of the parameters of a detection time window in an excitable tissue control device. The method includes applying electrodes to a first cardiac site and a second cardiac site of a patient and electrically connecting the electrodes to a data collecting device. The device is then operated under a plurality of different cardiac conditions to obtain a plurality of different histogram data sets. Each histogram data set represents a cumulative time distribution histogram of cardiac depolarization events detected at the second cardiac site in a plurality of cardiac beats. Each histogram data set is defined by a plurality of histogram parameters having values indicative of the cardiac conditions common to the plurality of cardiac beats used to obtain the histogram data set. The histogram parameters include a sensitivity level parameter representing the sensitivity level used for detecting the cardiac depolarization events of the plurality of cardiac beats at the second cardiac site. Another histogram parameter represents the range of values of the beat to beat time interval for the beats who'"'"'s data is included in the histogram data set. Another histogram parameter has values indicating if the beats who'"'"'s data is included in the histogram data set were acquired under conditions in which the delivery of non-excitatory ETC signals substantially affected or did not substantially affect the velocity of propagation of depolarization waves in the myocardium. Another histogram parameter, which may be used in devices having pacing capability has values indicating whether the beats who'"'"'s data is included in the histogram data set are paced beats or non-paced beats. The histogram data sets are processed for computing a set of data usable for on-line setting of the parameters of a detection time window. This set of data may then be used for operating an implanted or external ETC device operatively connected to the electrodes.
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Citations
21 Claims
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1. A method for obtaining from a patient'"'"'s heart data useful for on-line determining of the parameters of an alert time window in an excitable tissue control device, the method comprising the steps of:
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Applying electrodes to a first cardiac site and a second cardiac site of said patient and electrically connecting said electrodes to a data collecting device;
Operating said device under a plurality of different cardiac conditions to obtain a plurality of different histogram data sets, each histogram data set of said plurality of histogram data sets represents a cumulative time distribution histogram of cardiac depolarization events detected at said second cardiac site in a plurality of cardiac beats, each histogram data set of said plurality of histogram data sets is associated with a plurality of histogram parameters, said histogram parameters have values indicative of the cardiac conditions common to said plurality of cardiac beats used to obtain said histogram data set, said histogram parameters include a sensitivity level parameter having a value indicative of the detection sensitivity level used for detecting said cardiac depolarization events of said plurality of cardiac beats at said second cardiac site; and
Processing said plurality of histogram data sets to compute a set of data usable for on-line determination of the parameters of said alert time window. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
Setting a selected value for said detection sensitivity level parameter, by selecting a value from a plurality of values indicative of the plurality of detection sensitivity levels operatively available in said data collecting device and adjusting said data collecting device to use the detection sensitivity level indicated by said selected value;
Updating the values of said histogram parameters in accordance with the current cardiac conditions;
selecting a histogram data set to be updated based on the current values of said plurality of histogram parameters;
triggering a data collection time interval having a first duration, said data collection time interval comprises a plurality of contiguous time bins having a second duration smaller than said first duration, each of said time bins is associated with a single data element of a plurality of data elements included in said histogram data set, the value stored in a data element of said plurality of data elements represents the number of depolarization events detected in a plurality of beats at said second cardiac site within said second duration of the time bin associated with said data element;
using the times of detection of depolarization events at said second cardiac site within the duration of said data collection time interval to update the number of detected depolarization events recorded in appropriate data elements of said histogram data set; and
repeating said steps of setting, updating, selecting, triggering and using for a desired number of cardiac beats.
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3. The method according to claim 2 wherein said triggering of said step of triggering a data collection time interval is initiated upon detecting a depolarization event at said first cardiac site.
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4. The method according to claim 2 wherein said selecting of said step of setting comprises randomly or pseudo-randomly selecting a value from said plurality of values indicative of the plurality detection sensitivity levels operatively available in said data collecting device.
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5. The method according to claim 2 wherein said selecting of said step of setting comprises selecting a single optimized value from said plurality of values based on the determining by an operator of said data collecting device of an optimal detection sensitivity level in a data collection session occurring prior to said step of setting.
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6. The method according to claim 2 wherein said selecting of said step of setting comprises selecting a value from said plurality of values in accordance with a predetermined schedule for periodically changing the detection sensitivity level, wherein said schedule is arranged to result in sufficient data being recorded for each different value of detection sensitivity level during the period of time used for data acquisition in said patient.
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7. The method according to claim 2 further including between said step of setting and said step of updating the step of delivering a pacing pulse to said heart.
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8. The method according to claim 2 further including the step of delivering a non-excitatory ETC signal to said heart after said data collection time interval is terminated.
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9. The method according to claim 1 wherein one of said plurality of histogram parameters is a cycle length category parameter, the value of said cycle length category parameter may be one of a plurality of preset values, each value of said plurality of preset values represents a predetermined range of beat to beat time intervals, and wherein the current value of said cycle length category represents a cycle length category having a range within which the current beat to beat time interval falls, wherein said current beat to beat time interval is defined as the time interval between the currently detected depolarization event at said first cardiac site and the depolarization event detected at said first cardiac site in the cardiac beat preceding the current cardiac beat.
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10. The method according to claim 9 wherein said first cardiac site is the right ventricle of said heart, said second cardiac site is the left ventricle of said heart and wherein said beat to beat time interval is the R-R interval computed from the time of detection of the right ventricular depolarization event of the current cardiac beat and the time of detection of the right ventricular depolarization event of the cardiac beat preceding said current cardiac beat.
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11. The method according to claim 9 wherein said first cardiac site is the right atrium of said heart, said second cardiac site is the left ventricle of said heart and wherein said beat to beat time interval is the A-A interval computed from the time of detection of the right atrial depolarization event of the current cardiac beat and the time of detection of the right atrial depolarization event of the cardiac beat preceding said current cardiac beat.
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12. The method according to claim 1 wherein one of said plurality of histogram parameters may have two possible different values, a first value representing a first cardiac condition in which any excitable tissue control signals which were applied to the heart prior to the current cardiac beat did not substantially change the conduction velocity of the depolarization wave through the myocardium and a second value different than said first value representing a second cardiac condition in which any excitable tissue control signals which were applied to the heart prior to the current cardiac beat substantially changed the conduction velocity of the depolarization wave through the myocardium.
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13. The method according to claim 1 wherein one of said plurality of histogram parameters may have a value equal to one of two possible different values, one value representing a third cardiac condition in which the current cardiac beat is evoked by the natural pacemaker of the heart and another value representing a fourth cardiac condition in which the current cardiac beat is evoked by a pacing pulse delivered to the myocardium by said data collecting device through one of said electrodes.
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14. The method according to claim 2 wherein said triggering of said step of triggering a data collecting time interval is initiated upon delivering by said data collection device of a pacing pulse to said heart through one of said electrodes.
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15. The method according to claim 1 wherein said step of operating further includes the step of pacing said heart thorough one of said electrodes.
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16. The method according to claim 15 wherein said step of pacing includes changing the A-V delay used for said pacing to change the ratio of paced and non-paced beats.
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17. The method according to claim 16 wherein said changing of said A-V delay is performed manually by the operator of said data collecting device.
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18. The method according to claim 16 wherein said changing of said A-V delay is performed automatically by said data collecting device.
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19. The method according to claim 1 wherein said data collecting device is implanted in said patient.
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20. The method according to claim 1 wherein said plurality of different histogram data sets obtained in said step of operating is telemetrically transmitted to an analyzing unit external to the body of said patient prior to said step of processing.
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21. The method according to claim 1 wherein said data collecting device connected to said electrodes is an analyzing unit disposed external to the body of said patient.
Specification