Methods and apparatus for sensing intracardiac signals for an inplantable cardiac pacemaker
First Claim
1. An apparatus for acquiring and detecting intracardial cardiac activity signals comprising:
- a passive filter having a passband width of from 0.1 Hz to 80 Hz, an input for receiving cardiac activity signals, and an output for providing filtered signals;
an amplifier integrated circuit including switched capacitors and having an input for receiving the filtered signals, a gain lower than 50, and an output for providing amplified signals in a dynamic range of approximately 0.8V;
an analog-to-digital converter with delta modulation, having a controllable frequency and step for converting an input analog signal to a digital value, an input for receiving the amplified signals, and an output for providing digital values corresponding to the amplified signals;
processor means for processing the digital values; and
means for detecting spontaneous cardiac events based on the processed digital values.
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Abstract
A circuit for use in an implantable cardiac pacemaker for use in processing intracardiac signals and methods of processing such signals. The circuit includes a passive filter 1 has a bandwidth of 0.1 to 80 Hz approximately. An amplifier 2 with switched capacitors presents at the output a dynamics of 0.8V approximately and a gain lower than 50. An analog-to-digital converter 3 with delta modulation, which is controllably variable in step and functions at two frequencies, one of 1 kHz approximately, the other of 4 kHz approximately. The circuit may be used for both processing said signals to identify spontaneous cardiac events and to telemeter an intracardiac ECG.
130 Citations
41 Claims
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1. An apparatus for acquiring and detecting intracardial cardiac activity signals comprising:
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a passive filter having a passband width of from 0.1 Hz to 80 Hz, an input for receiving cardiac activity signals, and an output for providing filtered signals; an amplifier integrated circuit including switched capacitors and having an input for receiving the filtered signals, a gain lower than 50, and an output for providing amplified signals in a dynamic range of approximately 0.8V; an analog-to-digital converter with delta modulation, having a controllable frequency and step for converting an input analog signal to a digital value, an input for receiving the amplified signals, and an output for providing digital values corresponding to the amplified signals; processor means for processing the digital values; and means for detecting spontaneous cardiac events based on the processed digital values. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A method of processing electrical signals corresponding to intracardiac activity comprising:
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(a) filtering the electrical signals to suppress frequencies below 0.1 Hz and above 80 Hz; (b) providing an amplifier integrated circuit having switched capacitors, a dynamic range of 0.8V and a gain of less than 50, and amplifying the filtered signal by said amplifier; (c) providing a digital to analog converter (ADC) having delta modulation and a controllable frequency and step; (d) selecting the ADC frequency and step based on previously sensed amplified signals; (e) converting said amplified signals to digital values by said ADC at the selected frequency and step; and (f) processing said digital values to identify the occurrence of spontaneous atrial and/or ventricular cardiac events. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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35. A circuit for processing electrical signals corresponding to intracardiac activity for an implantable cardiac pacemaker comprising:
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a band pass filter having low cutoff frequency at about 0.1 Hz and a high cutoff frequency at about 80 Hz; an amplifier integrated circuit having switched capacitors, a low gain of less than 50, and a dynamic range on the order of 0.8V, said amplifier being connected to the filter to amplify the filtered electrical signals; a digital to analog converter (ADC) having delta modulation and a controllable frequency and step for converting an analog signal to a digital value, said ADC being controlled to convert said amplified signals to digital values. - View Dependent Claims (36, 37, 38)
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39. An implantable cardiac monitoring device comprising:
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a lead for receiving electrical signals corresponding to intracardiac electrical activity; a band pass filter having low cutoff frequency at about 0.1 Hz and a high cutoff frequency at about 80 Hz, the filter having an input connected to said lead and an output; an amplifier integrated circuit having switched capacitors, a low gain of less than 50, and a dynamic range on the order of 0.8V, said amplifier being connected to the filter output to amplify the filtered electrical signals; a analog to digital converter (ADC) having delta modulation and a controllable frequency and step for converting an analog signal to a digital signal, said ADC being controlled to convert said amplified signals to digital values. - View Dependent Claims (40, 41)
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Specification