Abstract: An improved apparatus and method for evaluating the need for, and performing as applicable, defibrillation. In one aspect, an improved defibrillation apparatus utilizing cardiographic impedance waveforms for determining cardiac output and accurately correlating this output to shockable or non-shockable cardiac conditions is disclosed. One exemplary embodiment uses electrodes having optimal spacing to enhance the accuracy of the impedance measurement. Another exemplary embodiment uses time-scale processing of the waveforms to identify fiducial points therein. Yet another embodiment uses advanced decision logic (such as fuzzy logic) to perform the aforementioned evaluation. The use of pacing spike detection and beat parsing based thereon is also disclosed.

Abstract: An improved apparatus and method for evaluating, tuning and operating a physiologic stimulator such as an implantable pacemaker or defibrillator. In one exemplary embodiment, an impedance cardiography system is used to measure one or more cardiac functions such as stroke volume or mitral regurgitation as the parameters determining the operation of the pacemaker are varied, such as via a non-invasive pacemaker programming device. After a plurality of the parameters have been programmed in and corresponding measurements of stroke volume or mitral regurgitation obtained, the data is evaluated to determine one or more optimized parameter values.