THORACIC OR INTRACARDIAC IMPEDANCE DETECTION WITH AUTOMATIC VECTOR SELECTION
First Claim
1. A system comprising:
- an implantable medical device (IMD), the IMD comprising;
an impedance detector circuit, including inputs configured to receive impedance signals from different electrode configurations in a subject'"'"'s thorax;
a cardiac stroke signal filter circuit, coupled to the impedance detector circuit to receive the impedance signals and extract therefrom corresponding cardiac stroke signals;
a respiration signal filter circuit, coupled to the impedance detector circuit to receive the impedance signals and to extract therefrom corresponding respiration signals;
a cardiac stroke amplitude measurement circuit, coupled to the cardiac stroke signal filter circuit to receive the cardiac stroke signals and to extract therefrom corresponding cardiac stroke amplitudes;
a respiration amplitude measurement circuit, coupled to the respiration signal filter circuit to receive the respiration signals and to extract therefrom corresponding respiration amplitudes; and
a processor circuit, including instructions executable or otherwise interpretable to compute a comparative measurement between each cardiac stroke amplitude and each corresponding respiration amplitude from the same electrode configuration, and based on relative values of the comparative measurement associated with each electrode configuration to select a particular electrode configuration for use in obtaining at least one of a cardiac stroke signal and a respiration signal for use in a diagnostic or therapeutic algorithm.
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Abstract
This document discusses, among other things, 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.
85 Citations
20 Claims
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1. A system comprising:
an implantable medical device (IMD), the IMD comprising; an impedance detector circuit, including inputs configured to receive impedance signals from different electrode configurations in a subject'"'"'s thorax; a cardiac stroke signal filter circuit, coupled to the impedance detector circuit to receive the impedance signals and extract therefrom corresponding cardiac stroke signals; a respiration signal filter circuit, coupled to the impedance detector circuit to receive the impedance signals and to extract therefrom corresponding respiration signals; a cardiac stroke amplitude measurement circuit, coupled to the cardiac stroke signal filter circuit to receive the cardiac stroke signals and to extract therefrom corresponding cardiac stroke amplitudes; a respiration amplitude measurement circuit, coupled to the respiration signal filter circuit to receive the respiration signals and to extract therefrom corresponding respiration amplitudes; and a processor circuit, including instructions executable or otherwise interpretable to compute a comparative measurement between each cardiac stroke amplitude and each corresponding respiration amplitude from the same electrode configuration, and based on relative values of the comparative measurement associated with each electrode configuration to select a particular electrode configuration for use in obtaining at least one of a cardiac stroke signal and a respiration signal for use in a diagnostic or therapeutic algorithm. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A system comprising:
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an implantable medical device (IMD), the IMD comprising; an impedance detector circuit, configured to; measure a first impedance signal between at least first and second electrodes, which define a first electrode configuration, in a subject'"'"'s thorax; and measure 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; and a processor circuit, coupled to the impedance detector circuit, the processor circuit configured to; calculate a first figure of merit using the first impedance signal; calculate a second figure of merit using the second impedance signal; and use values of the first and second figures of merit as a basis for automatically selecting one of the first and second electrode configurations for subsequent diagnostic extraction of one of the first and second impedance signals; wherein the first and second figures of merit comprise at least one of;
(1) an amplitude measurement of a respiration component of the first and second impedance signals, respectively;
(2) an amplitude measurement of a cardiac stroke component of the first and second impedance signals, respectively;
or (3) an amplitude measurement of a near-DC fluid status component of the first and second impedance signals, respectively. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification