Accurate cardiac event detection in an implantable cardiac stimulus device
Inventors
Allavatam, Venugopal • Palreddy, Surekha • Sanghera, Rick • Warren, Jay A.
Assignees
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Publication Number
US-11413468-B2
Publication Date
2022-08-16
Expiration Date
Abstract
Signal analysis in an implanted cardiac monitoring and treatment device such as an implantable cardioverter defibrillator. In some examples, detected events are analyzed to identify changes in detected event amplitudes. When detected event amplitudes are dissimilar from one another, a first set of detection parameters may be invoked, and, when detected event amplitudes are similar to one another, a second set of detection parameters may be invoked. Additional examples determine whether the calculated heart rate is “high” or “low,” and then may select a third set of detection parameters for use when the calculated heart rate is high.
Core Innovation
The invention relates to event detection in an implantable medical device having a plurality of electrodes and operational circuitry coupled to the electrodes to receive cardiac signals. The operational circuitry detects a first cardiac electrical event and a second cardiac electrical event from the cardiac signal captured using the electrodes, and prepares to detect a third cardiac electrical event by selecting between first and second threshold shapes used for detecting cardiac electrical events.
The selection between the first and second threshold shapes is based on comparing the first cardiac electrical event to the second cardiac electrical event, where the first threshold shape is different from the second threshold shape. The operational circuitry selects the first threshold shape for detecting the third cardiac electrical event if the first and second cardiac electrical events are similar, and selects the second threshold shape if the first and second cardiac electrical events are dissimilar.
The disclosed approach can further refine the threshold shapes by specifying relative sensitivity between the threshold shapes and by configuring different threshold-shape dynamics via decay initiation time and decay time constant. The threshold shapes can be scaled based on an estimated peak amplitude of cardiac signals, and cardiac cycles can be detected, cardiac rate can be determined from the detected cardiac cycles, and therapy can be determined to be indicated based on the cardiac rate and issued accordingly.
Claims Coverage
The independent claim set includes 2 independent claims. The claims cover detecting a third cardiac electrical event by comparing a first and a second cardiac electrical event for similarity or dissimilarity and selecting between two different threshold shapes accordingly, resulting in detection of the third event using the selected threshold shape.
Selecting between first and second threshold shapes based on similarity of cardiac events
Preparing to detect a third cardiac electrical event by selecting between first and second threshold shapes used for detecting cardiac electrical events, comparing the first cardiac electrical event to the second cardiac electrical event, selecting the first threshold shape if the first and second cardiac electrical events are similar, selecting the second threshold shape if the first and second cardiac electrical events are dissimilar, and detecting the third cardiac electrical event using the selected threshold shape.
Configuring decay portion differences between threshold shapes
The first threshold shape and the second threshold shape include a decay portion starting at a decay initiation time with different decay initiation times, and each decay portion has a time constant of decay with different decay time constants between the first and second threshold shapes.
Scaling threshold shapes using estimated peak amplitude
Scaling first and second threshold shapes relative to an estimated peak amplitude of cardiac signals, and calculating the estimated peak amplitude by averaging a stored value with a first peak amplitude found for a cardiac electrical event.
Detecting cardiac cycles to determine cardiac rate and indicate therapy
Determining cardiac rate from detected cardiac cycles, determining that therapy is indicated based on the cardiac rate, and issuing therapy when therapy is indicated.
Across the independent claims, the core coverage is the event-by-event comparison of two cardiac electrical events to decide whether detected events are similar or dissimilar, and then selecting between two different threshold shapes to detect a third event. Dependent claim coverage further refines the two threshold shapes by relative sensitivity, decay initiation time and decay time constant differences, by scaling with an estimated peak amplitude, and in further dependents by converting detected cardiac cycles into a cardiac rate used to determine and issue therapy.
Stated Advantages
Not explicitly described in patent.
Documented Applications
Not explicitly described in patent.
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