Pacemaker with morphological filtering of sensed cardiac signals
First Claim
1. A cardiac pacemaker which utilizes sensed P-waves for control of pacing operation, the cardiac pacemaker further having P-wave sense means operative cyclically, said P-wave sense means comprising:
- signal means for obtaining an atrial signal from the patient'"'"'s atrium;
sampling means for providing a sampled atrial signal;
morphological filter means for filtering out the P-wave portion from said sampled atrial signal to obtain a residual signal without said P-wave portion; and
subtracting means for subtracting said residual signal from said sampled signal to obtain a P-wave signal without any substantial FFR-wave portion, andmeans for providing electrical stimulation to a patient'"'"'s heart.
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Accused Products
Abstract
A system and method are provided, particularly useful for an implantable cardiac pacemaker, for morphological filtering of sensed signals to reliably and accurately identify one or more specified wave portions of the sensed signals. In a first pacemaker embodiment, morphological filtering is done on the sensed atrial signal, whereby the P-wave peak is discriminated out, with the resulting signal minus the P-wave peak being then subtracted from the inputted atrial signal to provide the atrial peak, thereby effectively eliminating sensing of FFR-wave portions. By setting the morphological filter length to correspond to about the duration of the P-wave peak, or just slightly larger, and by adjusting sampling frequency to correspond to cardiac rate variations, there is provided optimized filtering consistent with low power consumption in an implantable device. In other embodiments, FFR-waves, T-waves, VT, SVT and sinus tachycardia are identified by using templates matched to the wave to be identified. The invention can be performed with either analog or digital embodiments, analog embodiments providing for lower power consumption.
120 Citations
42 Claims
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1. A cardiac pacemaker which utilizes sensed P-waves for control of pacing operation, the cardiac pacemaker further having P-wave sense means operative cyclically, said P-wave sense means comprising:
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signal means for obtaining an atrial signal from the patient'"'"'s atrium; sampling means for providing a sampled atrial signal; morphological filter means for filtering out the P-wave portion from said sampled atrial signal to obtain a residual signal without said P-wave portion; and subtracting means for subtracting said residual signal from said sampled signal to obtain a P-wave signal without any substantial FFR-wave portion, and means for providing electrical stimulation to a patient'"'"'s heart. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. An implantable pacemaker for delivering pace pulses to the patient'"'"'s heart, said pacemaker having sensing means for sensing atrial signals from said patient and control means for controlling pace pulse delivery as a function of sensed P-waves, comprising:
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sample means for sampling said atrial signal to provide sample pulses representative of said atrial signal; and filter means for filtering said sampled signal to provide P-wave signals representative of P-waves pulses contained within said atrial signal, said filter comprising a morphological filter with an M width of at least about the duration the peak of said P-waves pulses. - View Dependent Claims (17)
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18. A cardiac pacemaker having pulse generator means for delivering pace pulses to a patient'"'"'s heart, sensing means for sensing atrial and ventricular cardiac signals from said patient'"'"'s heart, and control means for controlling said pulse generator as a function of said sensed signals, said sensing means comprising:
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atrial sensing means for obtaining a P-wave portion of each atrial wave when a P-wave occurs, said atrial sensing means further comprising a first morphological filter circuit for capturing a peak portion of each said P-wave; ventricular sensing means for sensing at least one selected portion of the ventricular signal, said ventricular sensing means comprising a second morphological filter circuit for separating out a peak portion of said selected portion each time that it occurs; and template means for controlling each of said first and second morphological filters. - View Dependent Claims (19, 20, 21)
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22. A cardiac pacemaker having stimulus means for delivering stimulus pulses to a patient'"'"'s heart, comprising;
atrial sensing means having an electrode adapted to be positioned in an atrial chamber of said patient for obtaining atrial signals, a first morphological filter for identifying FFR-wave portions of said signals, and a second morphological filter for identifying P-wave portions of said atrial signals.
- 23. A cardiac pacemaker comprising stimulus means for delivering stimulus pulses to a patient'"'"'s heart, sensing means for sensing cardiac signals from at least one chamber of said patient'"'"'s heart, and a plurality of morphological filters, each of said filters being connected to receive said cardiac signals and having a template adapted to discriminate a respective feature of said cardiac signals.
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31. An implantable medical device which senses P-waves, the device having P-wave sense means operative cyclically, the P-wave sense means comprising:
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signal means for obtaining an atrial signal from the patient'"'"'s atrium; sampling means for providing a sampled atrial signal; morphological-type filter means for filtering out the P-wave portion from the sampled atrial signal to obtain a residual signal without the P-wave portion, the morphological-type filter comprising an open-close filter; and subtracting means for subtracting the residual signal from the sampled signal to obtain a P-wave signal without any substantial FFR-wave portion. - View Dependent Claims (32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42)
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Specification