Abstract: There is provided a system and method for continually monitoring the occurrence of contraction during stimulation of skeletal muscle which is employed in a cardiac assist-type system. During delivery of a periodic burst, or train of stimulus pulses, the impedance of the muscle between the electrodes through which the pulses are delivered is monitored, and evaluated to determine whether or not stimulation has been achieved. In a particular embodiment, the impedance and impedance derivative values are accumulated throughout the burst, and assessed to determine whether the impedance change corresponded to a full muscle contraction. In the event of failure to stimulate the muscle to contraction, the system can automatically adjust the pulse output parameters to achieve reliable contraction.

Abstract: A cardiac assist device having circadian muscle stimulation. In particular the present invention operates in one of two states, either day mode or night mode. During the day mode, muscle stimulation and conditioning are performed according to a first schedule. During the night mode, muscle stimulation and conditioning are performed according to a second schedule. In addition, the night mode is only reached if the night mode is permitted, a set number of sensed beats are less than the night mode rate, and the time of day is nighttime. The night mode is interrupted if the night mode is turned off, the time of day is daytime, or a set number of beats are greater than the night rate. In short, the present invention provides for skeletal muscle stimulation at a less fatiguing level during the night than during the day.

Abstract: A device and algorithm for a combined cardiomyostimulator and a cardiac pacer-cardioverter-defibrillator.

Abstract: An implantable heart-assist device including extra-aortic balloon pump (EAB pump) for use in cooperation with a fluid pump is disclosed. The extra-aortic balloon pump includes a rigid, generally cylindrical housing and a flexible, generally cylindrical diaphragm residing generally within a longitudinal passageway in the rigid housing and secured to the rigid housing so as to create a plurality of separate expansion chambers. A plurality of fluid communication ports are provided for passing fluid into and out of the respective expansion chambers. The rigid housing includes interior and exterior surfaces, proximal and distal ends, and a longitudinal passageway. The diaphragm has an inner surface which defines a longitudinal lumen within the longitudinal passageway. The longitudinal lumen has a longitudinal axis and the respective expansion chambers and corresponding fluid communication ports are oriented axisymmetrically in respect to the longitudinal axis.