Microprocessor controlled rate-responsive pacemaker having automatic rate ...

United States Patent [19]

Mann et al.

[li] Patent Number: [45] Date of Patent:

4,940,052 Jul. 10, 1990

[54] MICROPROCESSOR CONTROLLED

RATE-RESPONSIVE PACEMAKER HAVING
AUTOMATIC RATE RESPONSE
THRESHOLD ADJUSTMENT

[75] Inventors: Brian M. Mann, Los Angeles; John W. Poore, South Pasadena, both of Calif.

[73] Assignee: Siemens-Pacesetter, Inc., Sylmar, Calif.

[21] Appl. No.: 301,934

[22] Filed: Jan. 25, 1989

[51] Int. CI.* A61N1/00

[52] U.S. CI 128/419 PG; 128/419 PS

[58] Field of Search 128/419 P, 419 PG, 419 PS

[56] References Cited

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Servais et al., "Estimating Human Energy Expenditure

A rate-responsive pacemaker which includes a conventional programmable pulse generator, a physiological sensor, and a processor is disclosed which generates heart stimulation pulses on demand, or as otherwise programmed, as controlled by a rate control signal which is derived from the physiological sensor. The physiological sensor generates a raw signal which varies as a function of some physiological parameter, such as activity level to provide some indication of whether the heart rate should increase or decrease, and hence whether the pacemaker should change the rate at which pacing pulses are provided. The processor converts the raw signal to the sensor-indicated rate signal in accordance with a selectable transfer relationship which defines the sensor-indicated rate signal as a function of a set of discrete sensor level index signals. The sensorindicated rate signal remains at a minimum value or base rate for all sensor level index signals below a prescribed rate response threshold, with this rate response threshold being set automatically by the processor as a function of a running average of the sensor level index signals monitored over a prescribed time period.

47 Claims, 11 Drawing Sheets