Andros Incorporated

Novacor Medical Corporation

World Heart Corporation

Baxter International Inc.

Jal S Jassawalla

Peer M Portner

Phillip J Miller

Herbert Chen

David H LaForge

David H Laforge

Donald T Shannon

Tofy Mussivand

Kenneth D Clark

Ingvar Olaffson

A pumping system for assisting either or both ventricles of the heart. In one embodiment, separate devices are provided for each ventricle. In another embodiment, one device provides both right and left pumping. The pumping system is small, efficient, atraumatic, and fully implantable. In addition, the pumping system can provide pulsatile flow during systole. The ventricular assist device includes an actuator plate between a pair of serially connected pumping chambers that operate in a two-stroke mode, specifically a power stroke and a transfer stroke. The ventricular assist device also includes an electromagnetic drive system that provides adjustment to the pump pressure according to the current through an electromagnet. For the pumping system, springs provide a 'spring force' on the actuator plate that is towards the high-pressure pump chamber. The bias force allows the springs to store and deliver energy from the electromagnetic drive system to provide better utilization of the pump components, and to reduce the pump size and consumption of electricity.

Miniature, pulsatile implantable ventricular assist devices and methods of controlling ventricular assist devices

An implantable ventricular assist device (VAD) has a small size to provide full-implantable capabilities. The VAD has two variable-volume chambers and an actuator for expelling blood from the chambers in sequence and to a common outlet, thus operating as a positive-displacement pump. The variable-volume chambers may be flexible sacs and the pump is operable at a substantially continuous flow, such as during the systolic phase of the assisted ventricle. A method of operation includes operating the pump at a first frequency during systole and a second lower frequency during diastole. The VAD pump includes a pair of coils housed within a frame and disposed in a spaced relationship to generate a coil flux through a pair of poles. A plate including an armature and a magnet is disposed within the frame such that the armature is between the poles and the magnet is between the coils. Gaps are defined between the armature and each of the poles and the coil flux displaces the armature across the gap. The coil flux follows a donut-shaped path including the frame, one of the poles, one of the gaps, the armature, the other the gap, and the other the pole, and no coil flux passes through the magnet. The magnet is not subject to depolarization and may be made substantially smaller than those of conventional devices. The magnet generates a bias flux that offsets a portion of the coil flux around the frame. A spring may be provided to counteract the unstable action of the bias magnet. The volume of the chambers is a fraction of the ventricular volume, and may be about 20 ml. To pump a typical 80-ml volume of a left ventricle, the controller may activate the coils four times during systole, or once every 40 msec.

Implantable ventricular assist device

A smooth-walled non-crimped inflow conduit for an implantable ventricular assist system. The conduit has an internally smooth lumen surface for enhanced washing of the conduit under irregular blood flow conditions. The conduit includes a tubular graft body that may be formed of a knitted fabric sealed with bovine collagen or gelatin, or formed of closed structured PTFE. The conduit may include external ribbing or support to prevent inward collapse under negative pressure conditions and also protect against damage from inadvertent physical contact in the operating room. The external support may be bonded to the exterior or formed integrally with the tubular graft body. An outer reinforcement cage may be provided to help prevent gross distortion or damage to the tubular graft body. The ends of the tubular graft body are left unsupported and wrapped around opposed lips of conduit coupling structure to minimize blood contacting surfaces at junctions with other conduits or with the heart. The conduit may be provided in an implantable left ventricular assist system also including a pumping device, valved conduits, and a power supply.

Smooth ventricular assist device conduit

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.

Blood pumping system and method

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.

Implantable infusion device

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. With closure of the armatures, and with the sac still in an expanded condition, the main springs are disengaged from the associated preload spring and placed in a more stressed, more planar configuration, with the increased stress in each main spring being relieved by movement of the pusher plates toward one another.

Pump actuator

An infusion system is disclosed for delivering precisely regulated and variable dosages of drugs. The device includes a reservoir for containing the drug, a catheter for delivering drug to the body, and actuating means responsive to a signal applied externally of the body for initiating delivery of a precisely regulated dosage. The actuating means include; a solenoid driven miniature pump which is controlled by an implanted controller and driven by an implanted power source. The implanted controller provides a basal dosage rate which itself may be variable or constant and which may be altered by telemetry signals delivered from outside the body. In addition, the internal device is operable by an external unit which may be set at a different rate from that which the internal or implanted controller is set and which, in addition, provides power for operating the implanted device. The reservoir is maintained at zero gauge or slightly negative gauge pressure to prevent loss of the contents of the reservoir into the body in which the device is implanted in the event of a failure. A tube communicating between the reservoir and the catheter is bent around on itself in such a way as to prevent bubbles from entering the tube. The implanted power and control electronics may be overridden to provide power from an extra corporeal unit and is also programmable from the extra corporeal unit to adjust dosage rates. A bellows is used to maintain a constant pressure within the reservoir, and suitable plates are utilized to produce a capacitive signal indicating the volume remaining of the contents of the reservoir.

A medical infusion system is described employing a pump for conducting fluid or semi-solids from an upstream portion to a downstream portion of the system. The pump includes upstream and downstream conduit means and a removable cassette communicating between the two. The cassette has a window therein and a diaphragm spans the window. The cassette has inlet and outlet openings valvelessly communicating with the pumping chamber or cavity of the cassette. Fluid in the conduit is pumped by restricting and opening the conduit means at upstream and downstream locations, and displacing the contents of the cassette pumping chamber appropriately.

Medical infusion system

Multiple embodiments of an implantable infusion device for delivering precisely regulated dosages of drugs are disclosed, each device including reservoir means for containing the drug, catheter means for delivering the drug to the body and an actuating means which is responsive to a signal applied externally of the body for initiating delivery of a precisely regulated dosage. In one embodiment, the device is implanted subcutaneously to permit actuation by a solenoid driven element responsive to coded telemetry signal applied through the skin. In additional embodiments, the reservoir is pressurized for example, by means of vapor pressure or a mechanical spring, the drug under pressure in the reservoir being released in response to an externally applied signal.

A medical infusion system is described employing a pump for conducting fluid or semi-solids from an upstream portion to a downstream portion of the system. The pump includes conduit means defining, in part, a removable cassette having a window therein and a diaphragm spanning the window. The cassette has inlet and outlet openings valvelessly communicating with the pumping chamber or cavity of the cassette. Fluid in the conduit is pumped by restricting and opening the conduit means at three different locations, one of which is before the cassette and one of which is after the cassette and the third of which is at the diaphragm of the cassette.

A blood pumping device is described for internal use in humans or animals and which is particularly suitable for use as a left ventricular assist device. The device is comprised of a unitary pancake-shaped deformable sac of flexible resilient, blood compatible material. A pair of oppositely acting plates on each side of the pancake-shaped sac are moved toward and away from each other by the action of driving means to deform the sac and provide the pumping action. Inlets and outlets are arranged in the annular side wall of the sac.

Blood pumping device

A compensator designed to be implanted within a living body and connected to an implanted reciprocating blood pump. A housing defines a gas-tight chamber which is separated into front and rear portions by a flexible membrane. A piston attached to the membrane guides the movement of the membrane, and a spring mechanism which links the piston and the housing is designed to maintain substantially constant pressure in the front chamber throughout the discharge and fill strokes of the reciprocating blood pump. Two pivoted, diametrically opposed, compression springs are compressed at rest at the end of the fill stroke and exert a force on the membrane which overcomes the differential pressure acting in the opposite direction when the membrane moves so as to expand the rear chamber volume.

Compensator for implanted blood pump

A cassette is described for use in an intravenous delivery system having a pump. The volume of a main chamber defined by the cassette body is varied by a membrane in a wall thereof while unidirectional inlet and outlet valves maintain the direction of fluid flow into and out of the main chamber. A prechamber is positioned above the inlet port in order to accumulate air from the upstream portion of the intravenous delivery system in which the cassette is used.

Cassette for intravenous delivery system

A cassette is described for use in an intravenous delivery system having a pump. The volume of a main chamber defined by the cassette body is varied and unidirectional inlet and outlet valves maintain the fluid direction into and out of the main chamber. In the operating position of the cassette, the outlet valve is positioned to be in communication with any gas present in the main chamber. For the purpose of accumulating air from the upstream portion of the intravenous delivery system in which the cassette is used, a prechamber is positioned above the inlet port communicating therewith.

Cassette chamber for intravenous delivery system

An intravenous and intra arterial delivery system is described having a disposable cassette actuated by a pump and control electronics for providing positive but variable delivery rates. The cassette is self-priming and provides protection against the delivery of air by being unable to impel air, and means provide an indication of excessive air in the cassette. The electronics has low power consumption so as to be suitable for battery operation, such as by way of rechargeable batteries. A pressure sensor in the delivery line may be used to sense infiltration. The system further features a provision for predetermining the amount of fluid to be delivered, and a detection system for detecting an empty supply bottle.

Growing community of inventors

San Francisco, CA, United States of America

Jal S Jassawalla