Abstract: A heart-assist system and a method for operating same are described in which a pump is connected to a ventricle to receive output therefrom. An actuator operates to cause the pump to conduct a fill cycle in which it receives output from the ventricle to which it is connected, and to conduct an eject cycle in which the contents of the pump are expelled. The time of initiation of at least one of the fill cycle and the eject cycle is varied in relation to systole of the ventricle to which the pump is connected to thereby vary the loading of the ventricle. Several techniques for detecting termination of systole are described including a compliant stop on the pump.

Abstract: A biventricular circulatory support system for a human patient is described. A mechanical first pump for assuming at least a part of the pumping load of the patient's left ventricle is implanted in the patient. A second pump for assuming at least a part of the pumping load of the patient's right ventricle is also implanted. The second pump includes a surgically prepared skeletal muscle pedicle with nerves and blood supply substantially intact. The muscle pedicle is applied directly to the right ventrical or is applied to an artificial pump sac. Electrical signals are applied to the first and second pumps as appropriate to cause pumping action in a predetermined relationship.

Abstract: An implanted blood pump system is described wherein power for driving the pump is provided by a transcutaneous transformer having an external primary winding and an implanted secondary winding. Control of the driving voltage to the pump is provided by an implanted shunt regulator. Voltage applied to the primary winding is controlled in accordance with the power factor sensed in the primary winding.

Abstract: An improved implantable infusion device for delivering precisely regulated doses of fluid into the body of a patient is disclosed. The device utilizes a resilient non-compliant pump bellows that is directly coupled by a gear train to a motor. The bellows is biased toward the expanded position and this factor, combined with the mechanical inertia of the gear train, substantially eliminates the danger of an overdose of infusate being released into the patient.

Abstract: An actuator is described for use in a pump having a pump chamber whose contents are expelled by movement of a pair of pusher plates toward one another. The actuator includes opposed solenoid armatures which are operable for movement between open and closed positions. The armatures are each operatively connected to an associated pusher plate by a main spring which is attached at one end to the back end of the armature, extends through a front-to-back slot in an armature core, and is connected at its opposite end to the pusher plate. A pair of preload springs carried on each armature and disposed on either side of the associated main spring acts to hold the main spring in a prestressed condition prior to solenoid actuation.

Abstract: A chamber structure in a blood pump or the like is described. The structure includes a deformable sac having an annular side wall which is held in a rigid condition, and a pair of opposed circular walls, each joined to the annular side wall through a flexible annular wall portion. A circular pusher plate acting against each circular wall has an initial deflection position at which the associated flexible wall portion in the sac takes the form of a circumferentially uniform roll having an outwardly convex, bulged cross sectional curvature. The rolls in the sac maintain their circumferentially uniform, bulge-like character as the pusher plates are moved toward inwardly moved positions.

Abstract: The invention discloses a novel process for producing covalently bonded laminated structures composed of polyurethane elastomer and vulcanized rubber layers. As the joining means for covalently bonding the polyurethane elastomer and vulcanizable rubber laminates the process utilizes novel grafted polyurethane joining compositions comprised of polyurethane elastomer, a polyisocyanate, and a hydroxyl containing polybutadiene difunctional linker molecule. In practicing the process of the invention, the grafted polyurethane joining composition is first prepared by means that create covalent chemical bonds between the polyurethane elastomer and a first functional (NCO) group on the polyisocyanate, as well as between a hydroxyl on the polybutadiene difunctional linker molecule and a second functional (NCO) group on the polyisocyanate. This novel grafted polyurethane composition is then used to bond layers of polyurethane elastomer to layers of vulcanizable rubber.

Abstract: A solenoid closure servo control eliminates impact of the solenoid poles against each other upon closure of the device. A model of the device closure is obtained from a parameter of initial gap. During closure of the device, the rate of closure of the gap of the solenoid and the force in balance between the spring and magnetic force is calculated and compared to the model. Imbalances are corrected by applying a corrective voltage to the solenoid coils.

Abstract: Real time servo control in a nonlinear, cyclical dynamic system adjusts the energy applied to a prime mover from a source of the energy as a linear function of an error between the measured load characteristics and modeled load characteristics. The modeled load characteristics are linearized as a function of the initial conditions of the load at the beginning of each cycle.

Abstract: A pump is described in which a flexible enclosure defines a pump chamber whose contents are expelled by movement of a pusher plate engaged with the enclosure. The pusher plate is moved by an elongate beam spring interconnecting the pusher plate with a solenoid drive mechanism. Solenoid actuation causes flexing of the beam spring from a relatively less stressed to a relatively more stressed position, the increased stress in the spring being relieved by pusher element movement. A preferred embodiment of the invention includes a symmetrical arrangement of opposed pusher elements and associated beam springs.