Kizakevich, P., & Teague, S. M. (1990). IPC No. U.S.Impedance cardiometer (Patent No. 4905705.)
A heart monitoring system for assessing a patient's cardiaccondition. Bioimpedance components induce an electric currentthrough the thorax of a patient's body and a first signalrepresenting amplitude of transthoracic impedance as a function oftime is obtained. Electrocardiograph components obtain anelectrocardiograph signal from the patient simultaneously with thefirst signal. First processing circuitry is connected to thebioimpedance components for processing the first signal andproducing therefrom a second signal representing cardiovascularhemodynamic changes as a function of time. Second processingcircuitry is connected to the electrocardiograph components formeasuring changes in the electrocardiograph signal. An analyzer isconnected to the first and second processing circuits for producingan output indicating changes in a portion of the second signal overa period of time relative to changes in the electrocardiographsignal over the same period of time. A presentation device presentsa visualization of the output of the analyzer for use in providingan assessment of cardiac condition.