Cardiac arrhythmia detection system for an implantable stimulation device
First Claim
1. An implantable cardiac event detection system for eliminating sensing of high amplitude T-waves, the system including an implantable lead that transmits an electrogram signal from a heart, comprising:
- an amplifier, coupled to the implantable lead, for amplifying an electrogram signal;
threshold detection means, coupled to the amplifier, for detecting an occurrence of an R-wave in the electrogram signal whenever the magnitude of the electrogram signal exceeds a threshold value;
timing means for generating a delay period following the detection of an R-wave; and
control means, responsive to the detection of the R-wave, for dynamically changing the threshold value from an initial value to a temporary value following the delay period, and then gradually returning the threshold value from the temporary value back to the initial value in accordance with a prescribed slope, so that a high amplitude T-wave that follows the R-wave is not sensed.
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Abstract
A cardiac event and arrhythmia detection system and method detects arrhythmic cardiac activity or other information from an electrogram signal of a heart. The system senses the electrogram signal through an electrogram lead, preliminarily processes the signal, and converts it to a plurality of discrete digital signals, each of which represents the magnitude of the electrogram signal at a prescribed sample time. The discrete digital signals are applied to both a cardiac event detector which has a dynamic threshold which is programmably adjustable so that T-waves are not sensed and a morphology detector. The morphology detector detects selected changes in the morphology (shape) of the electrogram signal, wherein such changes automatically control the sensitivity (gain and/or threshold) used to detect cardiac events. The occurrence of a prescribed amount of change in the detected morphology over time indicates the occurrence of a prescribed arrhythmic cardiac condition.
111 Citations
22 Claims
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1. An implantable cardiac event detection system for eliminating sensing of high amplitude T-waves, the system including an implantable lead that transmits an electrogram signal from a heart, comprising:
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an amplifier, coupled to the implantable lead, for amplifying an electrogram signal; threshold detection means, coupled to the amplifier, for detecting an occurrence of an R-wave in the electrogram signal whenever the magnitude of the electrogram signal exceeds a threshold value; timing means for generating a delay period following the detection of an R-wave; and control means, responsive to the detection of the R-wave, for dynamically changing the threshold value from an initial value to a temporary value following the delay period, and then gradually returning the threshold value from the temporary value back to the initial value in accordance with a prescribed slope, so that a high amplitude T-wave that follows the R-wave is not sensed. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An implantable cardiac event detection system having an improved dual-sensing means for detecting cardiac arrhythmias, the system including an implantable lead that transmits an electrogram signal from a heart, the improvement comprising:
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an amplifier, coupled to the implantable lead, for amplifying an electrogram signal; threshold detection means, coupled to the amplifier, for detecting an occurrence of an R-wave in the electrogram signal whenever the magnitude of the electrogram signal exceeds a threshold value; control means for programmably selecting one of a semi-automatic sensing mode and an automatic sensing mode for the detection of cardiac arrhythmias, and for programmably changing the threshold value from an initial value to a temporary value in response to a detected R-wave, the initial value being programmable in the semi-automatic mode and fixed in the automatic mode, and then gradually returning the threshold value from the temporary value back to the initial value in accordance with a desired slope as defined by the programmed sensing mode, so that a high amplitude T-wave that follows the R-wave is not sensed and arrhythmias can be reliably detected in one of the automatic and the semi-automatic mode. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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Specification