Means and method for the detection of cardiac events
First Claim
1. A system for identifying an ischemic event in a human patient including:
- at least two electrodes implanted in the patient for obtaining an electrical signal from the patient'"'"'s heart;
an implanted device including;
(a) analog-to-digital converter circuitry for digitizing the electrical signal to produce a multiplicity of segments, each having a duration of least 1 second, each of the periods between successive segments being at least as long as the segment duration;
(b) memory means designed to store a first segment at a first predetermined time;
(c) memory means designed to store a recently collected segment at a second time that is later than the first predetermined time;
(d) processor means coupled to said memory means for comparing the ST segment voltage of at least one beat of the recently collected segment at the second time with the average ST segment voltage of at least two beats of the first segment stored in the memory means at the first predetermined time; and
,(e) means for identifying that the ischemic event has occurred by applying a test that is based on whether the difference between the ST segment voltage of the at least one beat of the recently collected segment and the average ST segment voltage of the at least two beats of the first segment exceeds a detection threshold, wherein the detection threshold is a preset percentage of the average signal amplitude of the at least two beats of the first segment.
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Accused Products
Abstract
Disclosed is a system for the detection of cardiac events that includes an implanted device called a cardiosaver, a physician'"'"'s programmer and an external alarm system. The system is designed to provide early detection of cardiac events such as acute myocardial infarction or exercise induced myocardial ischemia caused by an increased heart rate or exertion. The system can also alert the patient with a less urgent alarm if a heart arrhythmia is detected. Using different algorithms, the cardiosaver can detect a change in the patient'"'"'s electrogram that is indicative of a cardiac event within five minutes after it occurs and then automatically warn the patient that the event is occurring. To provide this warning, the system includes an internal alarm sub-system (internal alarm means) within the cardiosaver and/or an external alarm system (external alarm means) which are activated after the ST segment of the electrogram exceeds a preset threshold.
29 Citations
16 Claims
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1. A system for identifying an ischemic event in a human patient including:
- at least two electrodes implanted in the patient for obtaining an electrical signal from the patient'"'"'s heart;
an implanted device including;(a) analog-to-digital converter circuitry for digitizing the electrical signal to produce a multiplicity of segments, each having a duration of least 1 second, each of the periods between successive segments being at least as long as the segment duration; (b) memory means designed to store a first segment at a first predetermined time; (c) memory means designed to store a recently collected segment at a second time that is later than the first predetermined time; (d) processor means coupled to said memory means for comparing the ST segment voltage of at least one beat of the recently collected segment at the second time with the average ST segment voltage of at least two beats of the first segment stored in the memory means at the first predetermined time; and
,(e) means for identifying that the ischemic event has occurred by applying a test that is based on whether the difference between the ST segment voltage of the at least one beat of the recently collected segment and the average ST segment voltage of the at least two beats of the first segment exceeds a detection threshold, wherein the detection threshold is a preset percentage of the average signal amplitude of the at least two beats of the first segment. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
- at least two electrodes implanted in the patient for obtaining an electrical signal from the patient'"'"'s heart;
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10. A system for identifying an ischemic event in a human patient including:
- at least two electrodes implanted in the patient for obtaining an electrical signal from the patient'"'"'s heart;
an implanted device including;(a) analog-to-digital converter circuitry for digitizing the electrical signal; (b) a memory; (c) a processor configured to; (i) compute ST segment deviation of a first plurality of beats within the electrical signal; (ii) compute a measure of QRS amplitude for the first plurality of beats; (iii) compute ST segment deviation of a second plurality of beats within the electrical signal, wherein the second plurality of beats occur after the first plurality of beats; (iv) compute a measure of the difference between the ST segment deviations of the first plurality of beats and the ST segment deviations of the second plurality of beats; (v) apply an ischemia detection test that is based on a comparison of the measure of the difference and a threshold, wherein the test is further based on the measure of QRS amplitude of the first plurality of beats. - View Dependent Claims (11, 12, 13, 14, 15, 16)
- at least two electrodes implanted in the patient for obtaining an electrical signal from the patient'"'"'s heart;
Specification