Thoracic or intracardiac impedance detection with automatic vector selection
First Claim
1. A method comprising:
- measuring a first impedance signal between at least first and second electrodes, which define a first electrode configuration, in a subject'"'"'s thorax;
extracting from the first impedance signal, a first cardiac stroke signal and a corresponding first respiration signal, if a corresponding heartbeat is not deemed arrhythmic;
computing a first comparative measurement between the first cardiac stroke signal and the first respiration signal;
measuring a second impedance signal between at least third and fourth electrodes, which define a second electrode configuration, in a subject'"'"'s thorax, wherein at least one of the third and fourth electrodes is a different electrode from at least one of the first and second electrodes;
extracting from the second impedance signal, a second cardiac stroke signal and a corresponding second respiration signal, if a corresponding heartbeat is not deemed arrhythmic;
computing a second comparative measurement between the second cardiac stroke signal and the second respiration signal; and
using the first and second comparative measurements as a basis for selecting of the first and second electrode configurations for subsequent extraction of at least one of the respiration and cardiac stroke signals.
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Abstract
Vector selection is automatically achieved via a thoracic or intracardiac impedance signal collected in a cardiac function management device or other implantable medical device that includes a test mode and a diagnostic mode. During a test mode, the device cycles through various electrode configurations for collecting thoracic impedance data. At least one figure of merit is calculated from the impedance data for each such electrode configuration. In one example, only non-arrhythmic beats are used for computing the figure of merit. A particular electrode configuration is automatically selected using the figure of merit. During a diagnostic mode, the device collects impedance data using the selected electrode configuration. In one example, the figure of merit includes a ratio of a cardiac stroke amplitude and a respiration amplitude. Other examples of the figure of merit are also described.
81 Citations
13 Claims
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1. A method comprising:
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measuring a first impedance signal between at least first and second electrodes, which define a first electrode configuration, in a subject'"'"'s thorax; extracting from the first impedance signal, a first cardiac stroke signal and a corresponding first respiration signal, if a corresponding heartbeat is not deemed arrhythmic; computing a first comparative measurement between the first cardiac stroke signal and the first respiration signal; measuring a second impedance signal between at least third and fourth electrodes, which define a second electrode configuration, in a subject'"'"'s thorax, wherein at least one of the third and fourth electrodes is a different electrode from at least one of the first and second electrodes; extracting from the second impedance signal, a second cardiac stroke signal and a corresponding second respiration signal, if a corresponding heartbeat is not deemed arrhythmic; computing a second comparative measurement between the second cardiac stroke signal and the second respiration signal; and using the first and second comparative measurements as a basis for selecting of the first and second electrode configurations for subsequent extraction of at least one of the respiration and cardiac stroke signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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Specification