Implantable medical device having means for suppressing thermally induced signals from piezoelectric sensors and method thereof
AssigneePacesetter, Inc.
InventorsSaid Mortazavi, Gene A. Bornzin
Life of this patent
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Abstract
A pyroelectric suppressor circuit for preventing undesirable thermally induced signals generated by a piezoelectric physical activity sensor from reaching processor circuitry within an implantable medical device is provided. The thermally induced signals typically have frequencies below a frequency in the range from about 0.1 mHz to about 10 mHz. The suppressor circuit provides a high-pass filter that rejects signals that have frequencies associated with thermally induced signals. Signals having frequencies greater than a frequency in the range from about 0.1 mHz to about 10 mHz, which correspond to patient activity, are passed on to processing circuitry of the implantable medical device.
Claims23
A rate-responsive pacemaker comprising:
- a piezoelectric sensor for generating sensor signals, the sensor signals including signals representative of physical activity and thermally induced signals;
- pulse generating circuitry for generating pacing pulses at an adjustable rate;
- processor circuitry for determining the rate at which the pulse generating circuitry generates pacing pulses in accordance with sensor signals generated by the piezoelectric sensor;
- and
- pyroelectric suppressor circuitry, coupled to the piezoelectric sensor and to the processor circuitry, for substantially limiting the sensor signals received by the processor circuitry to the signals representative of physical activity.
A method of providing rate-responsive pacing therapy for use with a pacemaker, the pacemaker including a piezoelectric sensor that generates sensor signals including signals representative of physical activity and thermally induced signals, and a pulse generator that generates pacing pulses at an adjustable rate, the method comprising the steps of:
- substantially limiting the signals generated by the piezoelectric sensor to the signals representative of physical activity;
- and
- determining the rate at which the pulse generator generates pacing pulses in accordance with the limited sensor signals, the rate thereby being determined in accordance with the signals representative of physical activity.
An implantable medical device comprising:
- a processor circuit;
- a piezoelectric activity sensor that generates sensor signals including signals representative of physical activity and signals representative of temperature fluctuations;
- and
- a suppressor circuit, the suppressor circuit comprising:
- first and second input terminals for receiving the sensor signals from the piezoelectric activity sensor;
- first and second output terminals for providing the signals representative of physical activity to the processor circuit;
- and
- a high-pass filter circuit disposed between the first and second input terminals and the first and second output terminals for limiting the sensor signals to those representative of physical activity.
A rate-responsive pacemaker, the rate-responsive pacemaker comprising:
- a processor circuit;
- means for providing pacing pulses to a heart, the providing means being electrically connected to the processor circuit;
- a piezoelectric activity sensor that generates sensor signals including signals representative of physical activity and signals representative of temperature fluctuations;
- and
- a suppressor circuit comprising:
- first and second input terminals for receiving the sensor signals from the piezoelectric activity sensor;
- first and second output terminals for providing the signals representative of physical activity to the processor circuit;
- and
- means disposed between the first and second input terminals and the first and second output terminals for limiting the sensor signals to those representative of physical activity.
Dependencies are inferred from the claim text.