Abstract: Impedance, e.g. sub-threshold impedance, is measured across the heart at selected cardiac cycle times as a measure of chamber expansion or contraction. One embodiment measures impedance over a long AV interval to obtain the minimum impedance, indicative of maximum ventricular expansion, in order to set the AV interval. Another embodiment measures impedance change over a cycle and varies the AV pace interval in a binary search to converge on the AV interval causing maximum impedance change indicative of maximum ventricular output. Another method varies the right ventricle to left ventricle (VV) interval to converge on an impedance maximum indicative of minimum cardiac volume at end systole. Another embodiment varies the VV interval to maximize impedance change. Other methods vary the AA interval to maximize impedance change over the entire cardiac cycle or during the atrial cycle.

Abstract: An air flow device for use in recording, analyzing, replicating, and generating breathing patterns. A piping structure provides receipt and transfer of pressurized gas through the device. The piping structure has a source connection for receiving a single constant source of pressurized gas. Aspirators are connected to the piping structure for receiving pressurized gas from the source connection and for selectively creating an output pressurization comprising a positive pressure gas flow and a negative pressure gas flow at a proportional solenoid valve. A balancing valve is connected to the piping structure for controlling and calibrating the output pressurization of the aspirators. A control system provides control of the aspirators, the balancing valve, and a solenoid valve. A solenoid valve is mechanically connected to the piping structure with pneumatic input and output connections and electronically connected to the control system with data input and output connections.