Patent ID: 6045512
Filing Date: 2000-04-04
Classification: A61B

Abstract:
A method for estimating a cardiac ejection fraction comprising the following steps:generating an injected indicator signal x(t) having a predetermined, time-varying signal profile and a predetermined duration;injecting an indicator at an upstream position in a heart according to the predetermined injected indicator signal x(t);sensing with an indicator concentration sensor a local indicator concentration signal y(t) at a downstream position, the region from and including the upstream position to and including the downstream position forming a channel for the blood;measuring a heart rate HR over the duration of the indicator signal x(t);generating a model of the channel as a predetermined function of the injected indicator signal x(t) and the indicator concentration signal y(t);continuously updating the model to provide as an output a modeled indicator decay parameter .tau. of the channel; andcontinuously estimating the cardiac ejection fraction EF of the heart as a predetermined function of the heart rate and of the modeled decay parameter .tau..