Apparatus and methods are described including a blood pump that is placed inside a body of subject. The blood pump includes an impeller that includes proximal and distal bushings, and that defines an axial lumen that extends from the proximal bushing to the distal bushing, a frame disposed around the impeller, and an axial shaft that passes through the proximal and distal bushings of the impeller. A distal end of a delivery catheter, and the frame and the impeller, are configured to be moved with respect to one another, to thereby cause the frame to assume a radially-constrained configuration by the frame becoming axially elongated, and cause the impeller to assume a radially-constrained configuration by the impeller becoming axially elongated. Other applications are also described.

A blood flow assist system can include an impeller assembly including an impeller shaft and an impeller on the impeller shaft, a primary flow pathway disposed along an exterior surface of the impeller. The system can include a rotor assembly at a proximal portion of the impeller shaft. A secondary flow pathway can be disposed along a lumen of the impeller shaft. During operation of the blood flow assist system, blood can be pumped proximally along the primary flow pathway and the secondary flow pathway. The system can include a sleeve bearing distal the impeller. The system can include a drive unit having a distal end disposed distal a proximal end of the second impeller. The drive unit comprising a drive magnet and a drive bearing between the drive magnet and the impeller assembly.

A blood flow assist system can include an impeller assembly including an impeller shaft and an impeller on the impeller shaft, a primary flow pathway disposed along an exterior surface of the impeller. The system can include a rotor assembly at a proximal portion of the impeller shaft. A secondary flow pathway can be disposed along a lumen of the impeller shaft. During operation of the blood flow assist system, blood can be pumped proximally along the primary flow pathway and the secondary flow pathway. The system can include a sleeve bearing distal the impeller. The system can include a drive unit having a distal end disposed distal a proximal end of the second impeller. The drive unit comprising a drive magnet and a drive bearing between the drive magnet and the impeller assembly.

A blood flow assist system can include an impeller assembly including an impeller shaft and an impeller on the impeller shaft, a primary flow pathway disposed along an exterior surface of the impeller. The system can include a rotor assembly at a proximal portion of the impeller shaft. A secondary flow pathway can be disposed along a lumen of the impeller shaft. During operation of the blood flow assist system, blood can be pumped proximally along the primary flow pathway and the secondary flow pathway. The system can include a sleeve bearing distal the impeller. The system can include a drive unit having a distal end disposed distal a proximal end of the second impeller. The drive unit comprising a drive magnet and a drive bearing between the drive magnet and the impeller assembly.

A blood flow assist system can include an impeller assembly including an impeller shaft and an impeller on the impeller shaft, a primary flow pathway disposed along an exterior surface of the impeller. The system can include a rotor assembly at a proximal portion of the impeller shaft. A secondary flow pathway can be disposed along a lumen of the impeller shaft. During operation of the blood flow assist system, blood can be pumped proximally along the primary flow pathway and the secondary flow pathway. The system can include a sleeve bearing distal the impeller. The system can include a drive unit having a distal end disposed distal a proximal end of the second impeller. The drive unit comprising a drive magnet and a drive bearing between the drive magnet and the impeller assembly.

A blood flow assist system can include an impeller assembly including an impeller shaft and an impeller on the impeller shaft, a primary flow pathway disposed along an exterior surface of the impeller. The system can include a rotor assembly at a proximal portion of the impeller shaft. A secondary flow pathway can be disposed along a lumen of the impeller shaft. During operation of the blood flow assist system, blood can be pumped proximally along the primary flow pathway and the secondary flow pathway. The system can include a sleeve bearing distal the impeller. The system can include a drive unit having a distal end disposed distal a proximal end of the second impeller. The drive unit comprising a drive magnet and a drive bearing between the drive magnet and the impeller assembly.

A blood pump system includes a blood pump and a corresponding controller. The blood pump includes an impeller that is sealed within the pump housing and hydrodynamically suspended within the pump housing. The pump impeller includes magnets, and is the rotor of a brushless direct current (DC) motor that is driven by electrical signals through stator wire coils in the pump housing, which creates a rotating magnetic field. The rotating magnetic field attracts the magnetized impeller and spins it with the rotating field. The controller provides field-oriented control for the brushless DC motor in the blood pump. The field-oriented control in the controller is provided in a programmable logic device separate from a control processor so that a software or hardware failure related to the control processor does not stop the blood pump. The field-oriented control allows sensing blood flow through the pump without having sensors in the blood stream.

A blood pump system includes a blood pump and a corresponding controller. The blood pump includes an impeller that is sealed within the pump housing and hydrodynamically suspended within the pump housing. The pump impeller includes magnets, and is the rotor of a brushless direct current (DC) motor that is driven by electrical signals through stator wire coils in the pump housing, which creates a rotating magnetic field. The rotating magnetic field attracts the magnetized impeller and spins it with the rotating field. The controller provides field-oriented control for the brushless DC motor in the blood pump. The field-oriented control in the controller is provided in a programmable logic device separate from a control processor so that a software or hardware failure related to the control processor does not stop the blood pump. The field-oriented control allows sensing blood flow through the pump without having sensors in the blood stream.

Methods and apparatuses for determining operational parameters of a blood pump comprising a rotor which transports the blood are provided. The change in the behaviour of at least one first and one second operational parameter, independently from each other, of the pump, is determined. A determination of the flow through the pump and/or the difference in pressure across the pump and/or the viscosity of the blood takes into account the determined change in behaviour of the at least two operational parameters. A modelling for a dynamic model of the known quantities may be carried out and an estimation method using a Kalman filter may be used.

Methods and apparatuses for determining operational parameters of a blood pump comprising a rotor which transports the blood are provided. The change in the behaviour of at least one first and one second operational parameter, independently from each other, of the pump, is determined. A determination of the flow through the pump and/or the difference in pressure across the pump and/or the viscosity of the blood takes into account the determined change in behaviour of the at least two operational parameters. A modelling for a dynamic model of the known quantities may be carried out and an estimation method using a Kalman filter may be used.