Cardio-synchronous impedance measurement system for an implantable stimulation device

摘要

In a pacing system, the pacing controller induces the leads to deliver an impedance measurement pulse to the right ventricle of the heart at at least a 15 ms interval during a window of time following detection of the R-wave or the delivery of a pacing pulse. The window of time corresponds to a period of ventricular ejection. The two or three measured impedance values are then used to determine an impedance slope that has a strong biological correlation to the contractility of the heart. The impedance slope is then used by the controller of the pacing system to adjust the delivery of pacing pulses for purposes such as maximizing contractility for a given AV delay, PV delay and pacing rate of pacing pulses.