Siemens-pacesetter, Inc.

Anders Lekholm

Roland Heinze

An implantable rate-responsive pacemaker is disclosed wherein two or more sensors indicative of physiological demand are utilized in a fashion designed to realize the advantages of both sensors in a circuit producing a rate command signal which is used to operate the pacemaker at an optimum pacing rate which will closely match physiological need of the patient. A rate matrix is used to produce a specific selected rate which is unique to the particular combination of sensor inputs which are being measured at the particular time. In the preferred embodiment, a plurality of rate matrices are provided, with the appropriate rate matrix to be used being selected by a switch matrix which monitors the logic-processed and time-processed signals from the sensors, the outputs of the processing circuitry being used to select a cell in the switch matrix which corresponds to the exact set of conditions currently being encountered by the sensors.

Rate-responsive pacemaker with circuitry for processing multiple sensor

An implantable rate-responsive pacemaker is disclosed wherein two or more sensors indicative of physiological demand are utilized in a fashion designed to realize the advantages of both sensors in a circuit producing a rate command signal which is used to operate the pacemaker at an optimum pacing rate which will closely match physiological need of the patient. A switch matrix monitors processed signals from the sensors to select a unique set of numerical coefficients indicated by the processed sensor signals. The selected set of numerical coefficients are used as weighting factors to weight the impact of each of the sensor signals in the calculation of a selected rate.

A rate-responsive pacing method and system senses the minimum blood oxygen saturation in the right atrium of a patient's heart and uses such minimum blood oxygen saturation as a control parameter for indicating the muscular activity of a patient. Because the oxygen content of the venous blood in the right atrium varies significantly as venous blood from all parts of the body is introduced therein, evidencing differing levels of oxygen demand throughout the patient's body, the minimum oxygen content of the venous blood provides an accurate and reliable measure of those portions of the patient's body experiencing the greatest oxygen demand, i.e., experiencing muscular activity. A rate-responsive pacing system includes means for sensing the minimum oxygen content in the right atrium over a prescribed time interval, and using such minimum oxygen content as a control parameter for adjusting the rate of the pacemaker.

Rate-responsive pacing method and system employing minimum blood oxygen

A flexible, planar patch electrode for cardiac defibrillation is fabricated from conductive wire mesh covered on an insulation side by a flexible layer of insulation. The electrode provides a substantial electrical contact area of 2-4 square inches and is shaped to provide an essentially rectangular base region with a plurality of protrusions extending longitudinally therefrom. he protrusions may be readily flexed to follow natural heart contours and slots between protrusions may be positioned to avoid features such as arteries near the surface of the heart. Central attachment of a lead within the base region minimizes current density and corresponding I.sup.2 R energy losses.

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Northridge, CA, United States of America

Anders Lekholm