Pacemaker with conditional atrial tracking capability
First Claim
1. A heart pacemaker, comprising:
- means for sensing atrial and ventricular electrical signals;
timing means for timing a preselected atrial rate limit interval in response to each sensed atrial signal, the timing of said interval being restarted for each sensed atrial signal;
means for pacing the ventricle in response to atrial signals sensed when said timing means has timed out said interval;
means for pacing the ventricle at a preselected demand rate when atrial signals are sensed while said interval is being timed out;
means for pacing the atrium at a preselected time following a paced or sensed ventricular signal if said interval has timed out before said preselected time; and
means for skipping a pace of the atrium if said interval is being timed at said preselected time.
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Accused Products
Abstract
An implantable microprocessor-controlled dual chamber heart pacemaker is programmed to control the timing of the pacing of the ventricle in response to high rate atrial signals. The microprocessor operates in conjunction with an atrial timer to detect atrial signals which occur at a rate in excess of a predefined atrial rate limit. The microprocessor paces the ventricle at a predefined desirable demand rate and inhibits pacing of the atrium in response to the high rate atrial activity. The microprocessor also controls the timing of an atrial refractory interval which includes an absolute refractory portion during which atrial signals are not detected and a relative refractory portion during which atrial signals are detected but are not tracked. The combined absolute and relative atrial refractory portions insure that relatively high rate atrial signals are detected and spurious signals conducted from the ventricle are ignored.
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Citations
21 Claims
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1. A heart pacemaker, comprising:
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means for sensing atrial and ventricular electrical signals; timing means for timing a preselected atrial rate limit interval in response to each sensed atrial signal, the timing of said interval being restarted for each sensed atrial signal; means for pacing the ventricle in response to atrial signals sensed when said timing means has timed out said interval; means for pacing the ventricle at a preselected demand rate when atrial signals are sensed while said interval is being timed out; means for pacing the atrium at a preselected time following a paced or sensed ventricular signal if said interval has timed out before said preselected time; and means for skipping a pace of the atrium if said interval is being timed at said preselected time. - View Dependent Claims (2, 3, 4, 5)
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6. A method for operating a dual chamber heart pacemaker comprising the steps of:
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detecting electrical signals in the atrium of the heart; restarting the timing of a preselected atrial rate limit interval for each detected atrial signal; pacing the atrium in a demand mode at a preselected point in time following each sensed or paced ventricular signal, unless one or more predetermined atrial skip pace conditions occur; skipping a pace of the atrium when at least one of said atrial skip pace conditions occurs; ignoring for ventricular pacing purposes atrial signals which occur while the atrial rate limit interval is being timed; ignoring for ventricular pacing purposes atrial signals which occur in one pacer timing cycle immediately following a previous cycle during which an atrial pace was skipped and a sensed or paced ventricular signal occurred while the atrial rate limit interval was being timed; pacing the ventricle at a preselected nominal rate in a demand mode when atrial signals are ignored and therefore cannot initiate a pace of the ventricle; and pacing the ventricle in a demand mode in response to each detected atrial signal which is not ignored. - View Dependent Claims (7, 8, 9)
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10. A heart pacemaker, comprising:
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means for detecting atrial electrical signals in the atrium of the heart; atrial timing means for detecting atrial signals which occur at a rate in excess of a preselected atrial rate limit; means for detecting electrical signals in the ventricle of the heart; means for pacing the ventricle, in the absence of superceding ventricular signals, in response to detected atrial signals which occur at a rate less than or equal to said atrial rate limit, said means for pacing including means for pacing the ventricle, in the absence of superceding ventricular signals, at a preselected rate less than said atrial rate limit in response to detected atrial signals which occur at a rate in excess of said atrial rate limit; and means for pacing the atrium at a preselected time following each detected ventricular signal or ventricular pace, in the absence of superceding atrial signals, unless said pace of the atrium would occur at a rate in excess of said atrial rate limit.
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11. A method for operating a dual chamber heart pacemaker, comprising:
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sensing atrial signals in the atrium of the heart; timing a preselected atrial rate limit interval in response to each sensed atrial signal; restarting the timing of the atrial rate limit interval if an atrial signal is sensed while the atrial rate limit interval is being timed; pacing the atrium in a demand mode at a preselected time after a sensed or paced ventricular signal, unless the atrial rate limit interval is being timed at said preselected time or a predefined stoppace condition exists at said preselected time; skipping a pace of the atrium when the atrial rate limit is being timed at said preselected time or when said predefined stoppace condition exists at the preselected time; pacing the ventricle in a demand mode in response to sensed atrial signals, unless the atrial signals occur while the atrial rate limit interval is being timed or occur in a timing cycle in which a predefined DDI condition exists; defining said DDI condition as existing in any timing cycle which is preceded by a timing cycle in which a pace of the atrium is skipped and a sensed or paced ventricular signal occurs while the atrial rate limit interval is being timed; timing an atrial refractory interval after each sensed or paced ventricular event; timing a preselected VA interval after each sensed or paced ventricular signal; and defining said stoppace condition as existing in any timing cycle in which the DDI condition exists and in which at least one atrial signal is detected during said VA interval and following said atrial refractory interval for the cycle. - View Dependent Claims (12, 13)
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14. A method for operating a dual chamber heart pacemaker, comprising the steps of:
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detecting electrical signals in the atrium and ventricle of a heart; pacing the ventricle in response to atrial signals which occur at a rate less than a predefined atrial rate limit; and pacing the atrium at a predefined time following each paced or sensed ventricular signal, unless an atrial signal is detected within a predefined atrial rate limit interval preceding said time, in which case the atrial pace is skipped. - View Dependent Claims (15)
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16. A method for operating a dual chamber pacemaker, comprising the steps of:
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detecting atrial and ventricular electrical signals; pacing the ventricle in response to atrial signals which occur at a rate less than a predefined atrial rate limit; timing an atrial rate limit interval in response to each atrial signal; pacing the atrium at a predefined time following each paced or sensed ventricular signal, unless said predefined time occurs when said atrial rate limit interval is being timed, in which case the atrial pace is skipped; setting an ASKIP flag when an atrial pace is skipped and clearing the flag in response to a succeeding paced or sensed ventricular signal; setting a DDI flag during one timing cycle following a timing cycle in which the ASKIP flag was set and a sensed or paced ventricular signal occurred while said atrial rate limit interval was being timed; while said DDI flag is set, preventing atrial signals from initiating a pace of the ventricle; timing an atrial refractory interval following each paced or sensed ventricular signal; setting a STOPPACE flag during said one timing cycle when the DDI flag is set and at least one atrial signal occurs after said atrial refractory interval for said one cycle; and skipping an atrial pace for said one timing cycle in which said STOPPACE flag is set.
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17. A dual chamber pacemaker for selectively tracking atrial signals and inhibiting pacing of the atrium, comprising:
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means for sensing atrial and ventricular electrical signals; timing means for timing a preselected atrial rate limit interval in response to each sensed atrial signal, the timing of said interval being restarted for each sensed atrial signal; means for tracking atrial signals sensed when said timing means has timed out said interval and for preventing tracking of atrial signals sensed when said timing means is timing out said interval; means for pacing the ventricle in response to tracked atrial signals; means for pacing the atrium at a preselected time following paced or sensed ventricular signals; and means for preventing pacing of the atrium at said preselected time when said timing means is timing out said interval. - View Dependent Claims (18, 19, 20, 21)
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Specification