Abstract: A ventricular assist device includes a housing including a pumping chamber. A stator assembly is supported in the housing. The stator assembly includes a core having a length measured along a pump axis. A rotating assembly is rotatable relative to the stator assembly about the pump axis. The rotating assembly includes an impeller positioned in the pumping chamber and a rotor magnet. The rotating assembly is movable axially along the pump axis relative to the pump housing and the stator assembly. The rotating assembly includes a rotor magnet configured and arranged such that the magnetic attraction of the rotor magnet to the core urges the rotating assembly to move axially relative to the stator assembly such that a flow regulating portion of the rotating assembly engages with a corresponding portion of the housing to block flow through the pumping chamber when the pump is at rest.

Abstract: A system and method of controlling the operation of a pump system includes modulating the speed of the pump and calculating a system condition parameter having a value related to the area of a hysteresis loop generated by a system operating parameter that varies in response to pump speed. The condition of the system is determined in response to the value of the system condition parameter.

Abstract: A method is provided of controlling a pump including a electrical motor coupled to a rotor which carries first and second impellers at opposite ends thereof. The method includes: (a) driving the rotor using the motor, so as to circulate fluid from the first impeller through a first fluid circuit, the second impeller, a second fluid circuit, and back to the first impeller; (b) determining a resistance of the first fluid circuit, based on a first motor parameter which is a function of electrical power delivered to the motor; (c) determining a flow rate through the first fluid circuit based on a second motor parameter which is a function of electrical power delivered to the motor; and (d) varying at least one operational parameter of the pump so as to maintain a predetermined relationship between the flow rate and the resistance of the first fluid circuit.

Abstract: A pump includes a housing, a stator supported in the housing, and a rotor assembly including a rotor supported in the housing for rotation relative to the stator about an axis. The stator includes a stator core, a first lamination wound around an axial portion of the stator core, and a second lamination wound around a second axial portion of the stator core. The first and second laminations are spaced from each other along the length of the stator core. The rotor includes a rotor core, a first magnet assembly that extends around an axial portion of the rotor core, and a second magnet assembly that extends around a second axial portion of the rotor core. The first and second magnet assemblies are spaced from each other along the length of the rotor.

Abstract: A method is provided of controlling a pump including a electrical motor coupled to a rotor which carries first and second impellers at opposite ends thereof. The method includes: (a) driving the rotor using the motor, so as to circulate fluid from the first impeller through a first fluid circuit, the second impeller, a second fluid circuit, and back to the first impeller; (b) determining a resistance of the first fluid circuit, based on a first motor parameter which is a function of electrical power delivered to the motor; (c) determining a flow rate through the first fluid circuit based on a second motor parameter which is a function of electrical power delivered to the motor; and (d) varying at least one operational parameter of the pump so as to maintain a predetermined relationship between the flow rate and the resistance of the first fluid circuit.

Abstract: A method is provided of controlling a pump including a electrical motor coupled to a rotor which carries first and second impellers at opposite ends thereof. The method includes: (a) driving the rotor using the motor, so as to circulate fluid from the first impeller through a first fluid circuit, the second impeller, a second fluid circuit, and back to the first impeller; (b) determining a resistance of the first fluid circuit, based on a first motor parameter; (c) determining a flow rate through the first fluid circuit based on a second motor parameter; and (d) varying at least one operational parameter of the pump so as to maintain a predetermined relationship between the flow rate and the resistance of the first fluid circuit.

Abstract: A pump includes a housing, a stator supported in the housing, and a rotor assembly including a rotor supported in the housing for rotation relative to the stator about an axis. The stator includes a stator core, a first lamination wound around an axial portion of the stator core, and a second lamination wound around a second axial portion of the stator core. The first and second laminations are spaced from each other along the length of the stator core. The rotor includes a rotor core, a first magnet assembly that extends around an axial portion of the rotor core, and a second magnet assembly that extends around a second axial portion of the rotor core. The first and second magnet assemblies are spaced from each other along the length of the rotor.

Abstract: A pump (10) includes a housing, a stator (20) supported in the housing, and a rotor assembly (30). The rotor assembly (30) includes a rotor (32) supported in the housing for rotation relative to the stator (20) about an axis (12). The rotor assembly (30) also includes a first impeller (34) operatively coupled to a first axial end of the rotor (32) for rotation with the rotor about the axis (12). The rotor assembly further includes a second impeller (36) operatively coupled to a second axial end of the rotor (32), opposite the first axial end, for rotation with the rotor about the axis (12). The rotor assembly (30) is movable along the axis (12) relative to the housing to adjust hydraulic performance characteristics of the pump (10).

Abstract: A method is provided of controlling a pump including a electrical motor coupled to a rotor which carries first and second impellers at opposite ends thereof. The method includes: (a) driving the rotor using the motor, so as to circulate fluid from the first impeller through a first fluid circuit, the second impeller, a second fluid circuit, and back to the first impeller; (b) determining a resistance of the first fluid circuit, based on a first motor parameter; (c) determining a flow rate through the first fluid circuit based on a second motor parameter; and (d) varying at least one operational parameter of the pump so as to maintain a predetermined relationship between the flow rate and the resistance of the first fluid circuit.

Abstract: A pump (10) includes a housing, a stator (20) supported in the housing, and a rotor assembly (30). The rotor assembly (30) includes a rotor (32) supported in the housing for rotation relative to the stator (20) about an axis (12). The rotor assembly (30) also includes a first impeller (34) operatively coupled to a first axial end of the rotor (32) for rotation with the rotor about the axis (12). The rotor assembly further includes a second impeller (36) operatively coupled to a second axial end of the rotor (32), opposite the first axial end, for rotation with the rotor about the axis (12). The rotor assembly (30) is movable along the axis (12) relative to the housing to adjust hydraulic performance characteristics of the pump (10).

Abstract: A pump (10) includes a housing, a stator (20) supported in the housing, and a rotor assembly (30). The rotor assembly (30) includes a rotor (32) supported in the housing for rotation relative to the stator (20) about an axis (12). The rotor assembly (30) also includes a first impeller (34) operatively coupled to a first axial end of the rotor (32) for rotation with the rotor about the axis (12). The rotor assembly further includes a second impeller (36) operatively coupled to a second axial end of the rotor (32), opposite the first axial end, for rotation with the rotor about the axis (12). The rotor assembly (30) is movable along the axis (12) relative to the housing to adjust hydraulic performance characteristics of the pump (10).

Abstract: In a left ventricular assist device (LVAD) a rotodynamic blood pump (10) is powered by a brushless DC motor (12). A power supply (14) supplies power to the motor (12). Three feedback channels, one for each of voltage, current, and motor speed lead to a microcontroller or microprocessor (18). The three feedback waveforms are analyzed, and from these waveforms, motor input power, patient heart rate, current pump flow rate, and systemic pressure are determined. The microprocessor (18) then calculates a desired flow rate proportional to the patient heart rate. The microprocessor communicates a new power output to a commutation circuit (16), which regulates power to the motor (12). The pump (10) also includes safety checks that are prioritized over desired pump flow. These include prevention of ventricular suction, low pulsatility, minimum and maximum pump speed, minimum speed-relative pump flow, minimum absolute pump flow, minimum and maximum motor input power.

Abstract: A system for pumping blood to assist or assume the cardiac function of a patient is characterized by a blood pump that exhibits a steep performance curve such that only small changes in pump flow occur for large changes in differential pressure across the pump. The pump therefore exhibits flow-limiting characteristics to protect the physiological system against harmful flow rates or pressures. Pump flow may also be limited by controlling the current provided to a driver from a power supply or by suitable restrictions within or external to the pump housing.

Abstract: A pump (10) includes a housing, a stator (20) supported in the housing, and a rotor assembly (30). The rotor assembly (30) includes a rotor (32) supported in the housing for rotation relative to the stator (20) about an axis (12). The rotor assembly (30) also includes a first impeller (34) operatively coupled to a first axial end of the rotor (32) for rotation with the rotor about the axis (12). The rotor assembly further includes a second impeller (36) operatively coupled to a second axial end of the rotor (32), opposite the first axial end, for rotation with the rotor about the axis (12). The rotor assembly (30) is movable along the axis (12) relative to the housing to adjust hydraulic performance characteristics of the pump (10).

Abstract: In a centrifugal flow blood pump, usable in left ventricular assist applications, blood is pumped from an inlet (16) to an outlet (22) by a primary impeller (18). A portion of the blood that enters the pump follows a secondary channel (24) where a secondary impeller (70) routes the blood to lubricate a bearing between an impeller assembly (14) and a post formed by a component of the pump housing. The unique shape of the secondary impeller (70) prevents blood stagnation and provides for a well-washed fluid bearing.

Abstract: In a left ventricular assist device (LVAD) a rotodynamic blood pump (10) is powered by a brushless DC motor (12). A power supply (14) supplies power to the motor (12). Three feedback channels, one for each of voltage, current, and motor speed lead to a microcontroller or microprocessor (18). The three feedback waveforms are analyzed, and from these waveforms, motor input power, patient heart rate, current pump flow rate, and systemic pressure are determined. The microprocessor (18) then calculates a desired flow rate proportional to the patient heart rate. The microprocessor communicates a new power output to a commutation circuit (16), which regulates power to the mortor (12). The pump (10) also includes safety checks that are prioritized over desired pump flow. These include prevention of ventricular suction, low pulsatility, minimum and maximum pump speed, minimum peed-relative pump flow, minimum absolute pump flow, minimum and maximum motor input power.

Abstract: In a centrifugal flow blood pump, usable in left ventricular assist applications, blood is pumped from an inlet (16) to an outlet (22) by a primary impeller (18). A portion of the blood that enters the pump follows a secondary channel (24) where a secondary impeller (70) routes the blood to lubricate a bearing between an impeller assembly (14) and a post formed by a component of the pump housing. The unique shape of the secondary impeller (70) prevents blood stagnation and provides for a well-washed fluid bearing.

Abstract: A system for pumping blood to assist or assume the cardiac function of a patient is characterized by a blood pump that exhibits a steep performance curve such that only small changes in pump flow occur for large changes in differential pressure across the pump. The pump therefore exhibits flow-limiting characteristics to protect the physiological system against harmful flow rates or pressures. Pump flow may also be limited by controlling the current provided to a driver from a power supply or by suitable restrictions within or external to the pump housing.

Abstract: A blood pump incorporates a blood lubricated journal bearing that is characterized by a non-circular geometry. In one embodiment, the stationary bearing element, or stator, of the bearing is provided with a semi-elliptical shaped outer surface in an area opposite the load bearing film. The journal bearing configuration ensures that the blood flow therethrough is adequate, that the integrity of the blood is preserved and that bearing stability is maintained.

Abstract: A sealless centrifugal blood pump is provided in which a rotatable impeller is supported in a pump housing by fluid bearings during operation. Rotational movement of the impeller is accomplished with an inverted motor for magnetically driving of the impeller and maintenance of the axial running position of the impeller relative to the housing. In an alternative embodiment, the axis of the rotor housing is radially displaced relative to the axes of drive element of the motor and the motor housing.