04686987 is referenced by 243 patents and cites 6 patents.

A biomedical apparatus capable of sensing changes in the heart's ventricular volume or stroke volume and then changing the operating performance of the device in a fashion as a function of stroke volume. A relatively low frequency signal (under 5 KHz) is applied between spaced electrodes disposed in the heart and the beating action of the heart serves to modulate this signal due to changes in impedance being sensed between these or other electrodes within the heart. The modulated carrier signal is then processed to remove R-wave and other electrical artifacts and then demodulated to remove the carrier frequency component leaving the envelope which is proportional to instantaneous ventricular volume. This envelope signal then contains stroke volume and ventricular volume information which can be used by the biomedical apparatus to vary its operating parameters. For example, a current proportional to changes in stroke volume may be injected into the timing circuit of a demand-type cardiac pacer pulse generator whereby the interpulse interval of the pulse generator is varied as a function of stroke volume.

Title
Biomedical method and apparatus for controlling the administration of therapy to a patient in response to changes in physiologic demand
Application Number
274875
Publication Number
4686987
Application Date
March 29, 1982
Publication Date
August 18, 1987
Inventor
Brian D Pederson
St. Paul
MN, US
Rodney W Salo
Columbia Heights
MN, US
Agent
Thomas J Nikolai
Orrin M Haugen
Assignee
Cardiac Pacemakers
MN, US
IPC
A61N 1/36
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