Rate adaptive pacemaker using impedance measurements and stroke volume calculations
First Claim
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1. A rate adaptive pacemaker comprising:
- an arrangement adapted for interaction with a subject for obtaining an electrical signal representing cardiac demand of said subject;
a computing unit supplied with said signal for calculating an actual cardiac output CO, and a cardiac output COrest for said subject at rest;
a pacing rate controller also supplied with said signal for generating, as an output, a pacing rate dependent on said cardiac demand; and
a pacing rate limiter connected to said computing unit and to said pacing rate controller for downwardly limiting said pacing rate, said pacing rate limiter calculating a stroke volume SV and a stroke volume SVrest for said subject at rest, and downwardly limiting said pacing rate so that a first predetermined relation CO>
COrest and a second predetermined relation SV/SVrest<
L are satisfied, wherein L is a predetermined constant in a range between 1.2 and 1.5.
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Abstract
A rate adaptive pacemaker comprises a means (2) for determining the demand of the patient'"'"'s organism, a pacing rate controlling means (16) for controlling the pacing rate in response to the patient'"'"'s demand, and a pacing rate limiting means (20) for preventing the pacing rate from becoming too low. The pacing rate limiting means is adapted to limit the pacing rate downwards such that a first predetermined relation is satisfied between actual cardiac output (CO) and cardiac output (COrest) for the patient in rest conditions and a second predetermined relation is satisfied between actual stroke volume (SV) and rest stroke volume (SVrest).
21 Citations
6 Claims
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1. A rate adaptive pacemaker comprising:
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an arrangement adapted for interaction with a subject for obtaining an electrical signal representing cardiac demand of said subject; a computing unit supplied with said signal for calculating an actual cardiac output CO, and a cardiac output COrest for said subject at rest; a pacing rate controller also supplied with said signal for generating, as an output, a pacing rate dependent on said cardiac demand; and a pacing rate limiter connected to said computing unit and to said pacing rate controller for downwardly limiting said pacing rate, said pacing rate limiter calculating a stroke volume SV and a stroke volume SVrest for said subject at rest, and downwardly limiting said pacing rate so that a first predetermined relation CO>
COrest and a second predetermined relation SV/SVrest<
L are satisfied, wherein L is a predetermined constant in a range between 1.2 and 1.5. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification