Pacemaker system and method with improved capture detection and threshold search
First Claim
1. A pacemaker system for pacing a patient, having stimulus means for generating and delivering stimulus pulses to said patient, ER means for sensing when a delivered stimulus pulse has evoked a response, and threshold means for determining a measure of pacing threshold to delivered stimulus pulses, said threshold means comprising:
- pulse pair means for controlling said stimulus means to cyclically generate and deliver pairs of stimulus pulses, the first pulse of each said pair being variable in output and the second pulse of said pulse pairs being a regular pacing pulse at an output level above the pacing threshold;
stabilization means for determining when said pulse pairs have been delivered for at least a predetermined stabilization period;
detection means operable at the end of said stabilization period for detecting which pulse of a said pulse pair delivered after said stabilization period evoked a heart response;
repeat means operable following a detection that said regular pulse evoked a cardiac response, for incrementing said first pulse output and for enabling said stabilization means to determine when stimulus pulse pairs with an incremental first pulse output have been delivered for a stabilization period following said incrementing;
threshold measuring means for determining when said incremented first pulse results in an evoked response, and for then storing the first pulse output value as said measure of pacing threshold; and
setting the output value of said stimulus pulses as a function of said measure of threshold.
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Abstract
There is provided a pacemaker system with capture verification and threshold testing, in which the pacemaker waits after each change in delivered pace pulses for a stabilization interval, in order to minimize polarization and enhance capture verification. The threshold test utilizes a pace pulse pair, comprising a prior search pulse which is varied during the test, and the regular pacing pulse which is above threshold. When delivery of the pulse pairs is initiated, the search pulse is adjusted to optimize polarization, and the pacemaker waits for predetermined stabilization period of time in order to allow for minimum polarization and to optimize capture detection. The search pulse is increased incrementally in output value toward threshold, and following each such increase the pacemaker waits for a stabilization interval. The pacemaker detects when capture is achieved by the search pulse, thereby providing an indication of threshold.
56 Citations
20 Claims
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1. A pacemaker system for pacing a patient, having stimulus means for generating and delivering stimulus pulses to said patient, ER means for sensing when a delivered stimulus pulse has evoked a response, and threshold means for determining a measure of pacing threshold to delivered stimulus pulses, said threshold means comprising:
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pulse pair means for controlling said stimulus means to cyclically generate and deliver pairs of stimulus pulses, the first pulse of each said pair being variable in output and the second pulse of said pulse pairs being a regular pacing pulse at an output level above the pacing threshold; stabilization means for determining when said pulse pairs have been delivered for at least a predetermined stabilization period; detection means operable at the end of said stabilization period for detecting which pulse of a said pulse pair delivered after said stabilization period evoked a heart response; repeat means operable following a detection that said regular pulse evoked a cardiac response, for incrementing said first pulse output and for enabling said stabilization means to determine when stimulus pulse pairs with an incremental first pulse output have been delivered for a stabilization period following said incrementing; threshold measuring means for determining when said incremented first pulse results in an evoked response, and for then storing the first pulse output value as said measure of pacing threshold; and setting the output value of said stimulus pulses as a function of said measure of threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method used in an implanted cardiac pacemaker for detecting when a stimulus pulse delivered to an electrode positioned in the patient'"'"'s heart evokes a cardiac response, comprising:
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adjusting said stimulus pulse to minimize resulting polarization sensed at said electrode following the delivered pulse; pacing with adjusted stimulus pulses for a predetermined stabilization interval; upon conclusion of the stabilization interval, delivering a next adjusted stimulus pulse, sensing the signal at said electrode; and determining from said sensed signal whether it represents an evoked cardiac response. - View Dependent Claims (12, 13, 14, 15, 16)
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17. A cardiac pacemaker system, having a stimulus generator for generating stimulus pulses, lead delivery means for delivering said pulses to at least one electrode positioned in a patient'"'"'s heart,
sensing means for sensing electric signals at said electrode following delivery of a stimulus pulse, and capture means for determining when a delivered stimulus has evoked a cardiac response, said capture means comprising: -
polarization control means for adjusting at least one parameter of said stimulus pulses so as to minimize polarization at said electrode resulting from a delivered pace pulse, stabilization control means for determining when said stimulus generator has generated said adjusted stimulus parameters for at least a predetermined stabilization interval, and detection means operative after said stabilization interval for sensing the signals at said electrode following one or more delivered adjusted stimulus pulses, and for determining from said sensed signal or signals whether said stimulus pulse is capturing the patient'"'"'s heart. - View Dependent Claims (18, 19, 20)
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Specification