Abstract: A processing system and method are provided for deriving an improved hemodynamic indicator from cardiac wall acceleration signals. The cardiac wall acceleration signals are provided by a cardiac wall motion sensor that responds to cardiac mechanical activity. The cardiac wall acceleration signals are integrated over time to derive cardiac wall velocity signals, which are further integrated over time to derive cardiac wall displacement signals. The cardiac wall displacement signals correlate to known hemodynamic indicators, and are shown to be strongly suggestive of hemodynamic performance. An implantable cardiac stimulating device which uses cardiac wall displacement signals to detect and discriminate cardiac arrhythmias is also provided.

Abstract: An accelerometer-based, multi-axis physical activity sensor for use with a rate-responsive pacemaker, and a method for fabricating the sensor, are provided. The multi-axis physical activity sensor includes a cantilever beam having a film of a piezoelectric polymer adhered to each surface of an electrically conductive substrate. The piezoelectric films are highly resistant to fracturing during manufacture and in use, and they provide a strong output signal when stressed in response to bodily accelerations. A mass is mounted to a free end of the cantilever beam, and is substantially offset with respect to a planar surface of the beam so as to impart multi-axis sensitivity to the physical activity sensor. The accelerometer-based, multi-axis physical activity sensor provides an output signal that is communicated to pacemaker circuitry using a pair of electrical conductors.

Abstract: A miniature, hybrid-mountable, accelerometer-based, physical activity sensor for use with a rate-responsive implantable stimulation device is provided. The physical activity sensor is constructed as a cantilever beam having a film of a piezoelectric polymer adhered to each surface of an electrically conductive substrate. The piezoelectric films are highly resistant to fracturing during manufacture and in use, and they provide a strong output signal when stressed in response to bodily accelerations. A pair of electrically conductive supports serve to anchor the physical activity sensor to a substrate and deliver the output signal provided by the sensor to circuitry within the rate-responsive implantable stimulation device. The physical activity sensor is adapted to be mounted directly to conductive traces on a suitable substrate, preferably an implantable stimulation device hybrid.