Implantable cardiac stimulation device having autocapture/autothreshold capability
First Claim
1. An implantable cardiac stimulation device for stimulating a patient'"'"'s heart through at least one electrode in electrical communication with selected cardiac tissue, the stimulation device comprising:
- a pulse generator that is configured to generate stimulation pulses at a selected amplitude for delivery to the at least one electrode;
a detection circuit that is configured to process cardiac signals to determine a presence or absence of an evoked response to each of the stimulation pulses; and
a controller coupled to the pulse generator, wherein the controller is operative to increase the amplitude of the stimulation pulses when an absence of evoked responses from at least X out of the last Y stimulation pulses exists, where Y is a value greater than 2 and X is a value less than Y, and wherein the controller is operative to maintain the amplitude of the stimulation pulses where there is no absence of evoked responses from X out of the last Y stimulation pulses.
1 Assignment
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Accused Products
Abstract
An improved system and method for performing autocapture/autothreshold detection in an implantable cardiac stimulation device or any device capable of stimulating some organ or tissue in the body. In some existing systems, loss-of-capture and capture decisions are based upon two consecutive cardiac events. However, such systems may be subject to subthreshold stimulation pulses that capture and lose capture on alternating pulses, trigeminy PVC sequences, or the like that require a higher stimulation pulse amplitude but cannot make this determination due to the two consecutive event requirement. Accordingly, in the present invention, the determination of whether there is a loss-of-capture is determined only according to paced events, i.e., ignoring intrinsic and PVC beats. Furthermore, the loss-of-capture determination is based upon X out of the last Y beats, where Y is greater than 2 and X is less than Y. Accordingly, consecutive loss-of-capture events are no longer required in determining the threshold level. In a further aspect, a preferred embodiment monitors cardiac events to detect a sequence of patterns that could indicate a trigeminy pattern and, if detected, the pacing rate is increased to attempt to break the pattern and thus permit the threshold level to be detected.
22 Citations
21 Claims
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1. An implantable cardiac stimulation device for stimulating a patient'"'"'s heart through at least one electrode in electrical communication with selected cardiac tissue, the stimulation device comprising:
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a pulse generator that is configured to generate stimulation pulses at a selected amplitude for delivery to the at least one electrode; a detection circuit that is configured to process cardiac signals to determine a presence or absence of an evoked response to each of the stimulation pulses; and a controller coupled to the pulse generator, wherein the controller is operative to increase the amplitude of the stimulation pulses when an absence of evoked responses from at least X out of the last Y stimulation pulses exists, where Y is a value greater than 2 and X is a value less than Y, and wherein the controller is operative to maintain the amplitude of the stimulation pulses where there is no absence of evoked responses from X out of the last Y stimulation pulses. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for stimulating a patient'"'"'s heart through at least one electrode in electrical communication with selected cardiac tissue, the method comprising:
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delivering a plurality of stimulation pulses to the patient'"'"'s heart, wherein each of the stimulation pulses has a selected amplitude; detecting a presence or absence of an evoked response for each stimulation pulse; increasing the amplitude of the stimulation pulses in response to an absence of evoked responses from at least X out of the last Y stimulation pulses, where Y is a value greater than 2 and X is a value less than Y; and maintaining the amplitude of the stimulation pulses where there is no absence of evoked responses from X out of the last Y stimulation pulses. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. An implantable cardiac stimulation device comprising:
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means for stimulating a patient'"'"'s heart at a selected amplitude; means for determining a presence or absence of an evoked response for each applied stimulation pulse; means for increasing the amplitude of the stimulation pulses when an absence of evoked responses from at least X out of the last Y stimulation pulses exists, where Y is a value greater than 2 and X is a value less than Y; and means for maintaining the amplitude of the stimulation pulses where there is no absence of evoked responses from at least X out of the last Y stimulation pulses. - View Dependent Claims (20, 21)
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Specification