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.

Apparatus and methods are described including a blood pump catheter that includes an axial shaft, and an impeller disposed on the axial shaft. A motor drives the impeller to pump blood, by rotating the impeller. A drive cable extends from the motor to the axial shaft, the drive cable being configured to impart rotational motion from the motor to the impeller by rotating. A distal tip portion is disposed at a distal end of the blood pump catheter. The drive cable, the axial shaft, and the distal tip portion define a continuous lumen therethrough from outside the subject's body to the distal end of the blood pump catheter. The continuous lumen facilitates insertion of the blood pump catheter into the subject's body over a guidewire, and, subsequently, provides a channel through which the purging fluid flows. Other applications are also described.

Apparatus and methods are described including a blood pump catheter that includes an axial shaft, and an impeller disposed on the axial shaft. A motor drives the impeller to pump blood, by rotating the impeller. A drive cable extends from the motor to the axial shaft, the drive cable being configured to impart rotational motion from the motor to the impeller by rotating. A distal tip portion is disposed at a distal end of the blood pump catheter. The drive cable, the axial shaft, and the distal tip portion define a continuous lumen therethrough from outside the subject's body to the distal end of the blood pump catheter. The continuous lumen facilitates insertion of the blood pump catheter into the subject's body over a guidewire, and, subsequently, provides a channel through which the purging fluid flows. Other applications are also described.

Apparatus and methods are described including a ventricular assist device that includes a tube configured to traverse a subject's aortic valve. The tube defines a generally-cylindrical central portion, and a proximal conical portion that narrows from a proximal end of the central portion to a proximal end of the tube. The tube defines one or more blood inlet openings in a vicinity of a distal end of the tube, and one or more blood outlet openings that extend axially from the central portion of the tube at least partially into the proximal conical portion of the tube. A blood pump pumps blood into the tube from the subject's left ventricle through the one or more blood inlet openings, and from the tube into the aorta through the one or more blood outlet openings. Other applications are also described.

Apparatus and methods are described including a ventricular assist device that includes a tube configured to traverse a subject's aortic valve. The tube defines a generally-cylindrical central portion, and a proximal conical portion that narrows from a proximal end of the central portion to a proximal end of the tube. The tube defines one or more blood inlet openings in a vicinity of a distal end of the tube, and one or more blood outlet openings that extend axially from the central portion of the tube at least partially into the proximal conical portion of the tube. A blood pump pumps blood into the tube from the subject's left ventricle through the one or more blood inlet openings, and from the tube into the aorta through the one or more blood outlet openings. Other applications are also described.

Apparatus and methods are described including a blood pump that includes an impeller, and a motor configured to drive the impeller to pump blood by rotating the impeller. The impeller is configured to undergo axial motion, in response to changes in a pressure against which the impeller is pumping. A sensor detects the axial motion of the impeller, and generates a sensor signal in response thereto. A computer processor receives the sensor signal and generates an output in response thereto. Other applications are also described.

Apparatus and methods are described including a blood pump that includes an impeller, and a motor configured to drive the impeller to pump blood by rotating the impeller. The impeller is configured to undergo axial motion, in response to changes in a pressure against which the impeller is pumping. A sensor detects the axial motion of the impeller, and generates a sensor signal in response thereto. A computer processor receives the sensor signal and generates an output in response thereto. Other applications are also described.

A method for operating a pump assembly, wherein the pump assembly has at least one first drive means for conveying a fluid and an electric motor for driving the first drive means, the electric motor comprising at least one stator and one rotor, the rotor being connected at least to the first drive means via a driveshaft. The electric motor draws power at least: i. in order to heat the rotor by means of induction; or ii. in order to drive the rotor, the driveshaft and the first drive means so that these components rotate about a common rotation axis at a speed of more than 0 revolutions per minute.

A vertical molten sulfur pump assembly includes a pump motor disposed in a top portion and an impeller disposed in a bottom portion, within an impeller casing. A pump inlet is disposed at the second end below the impeller casing. The vertical molten sulfur pump assembly is configured to pump molten sulfur into the inlet and upwards through a discharge passageway by rotation of the impeller. A vibration sensor and a temperature sensor are disposed on an external surface of the bottom portion, on or proximate to the impeller casing and the pump inlet. A temperature sensor is configured to measure a temperature of the molten sulfur proximate to the pump inlet. A vibration sensor includes a substrate comprising a polymer and a resonant layer, and resonant layer includes an electrically conductive nanomaterial and is configured to produce a resonant response in response to receiving a radio frequency signal.