Microbubbles detached from a blood circuit and a blood purification unit are discharged with the use of a backflow generated at the instant that a roller of a blood pump releases a squeezable tube. In a normal rotation step, a region filled with a priming solution after a priming step is closed by a closing unit, and a rotor of a blood pump is rotated normally until a roller of the blood pump releases a squeezable tube to generate a backflow. After the backflow is generated at the release of the squeezable tube by the roller of the blood pump, bubbles are moved by reversely rotating the rotor while disabling the closing by the closing unit. Thus, the bubbles are discharged through a discharge unit.

Microbubbles detached from a blood circuit and a blood purification unit are discharged with the use of a backflow generated at the instant that a roller of a blood pump releases a squeezable tube. In a normal rotation step, a region filled with a priming solution after a priming step is closed by a closing unit, and a rotor of a blood pump is rotated normally until a roller of the blood pump releases a squeezable tube to generate a backflow. After the backflow is generated at the release of the squeezable tube by the roller of the blood pump, bubbles are moved by reversely rotating the rotor while disabling the closing by the closing unit. Thus, the bubbles are discharged through a discharge unit.

Apparatus and methods are described including a blood pump that includes at least one motor configured to be disposed outside a body of a subject, a catheter, a proximal impeller disposed on the catheter and configured to pump blood by rotating, and a distal impeller disposed on the catheter. The distal impeller is configured to pump blood by rotating and is disposed on the catheter distally to the proximal impeller such that longitudinal centers of the proximal and distal impellers are separated from each other by at least 3 cm. Other applications are also described.

Apparatus and methods are described including a blood pump that includes at least one motor configured to be disposed outside a body of a subject, a catheter, a proximal impeller disposed on the catheter and configured to pump blood by rotating, and a distal impeller disposed on the catheter. The distal impeller is configured to pump blood by rotating and is disposed on the catheter distally to the proximal impeller such that longitudinal centers of the proximal and distal impellers are separated from each other by at least 3 cm. Other applications are also described.

Apparatus and methods are described including a blood pump that includes a catheter, a first impeller disposed on the catheter, and a second impeller disposed on the catheter, proximally to the first impeller. A motor drives the first and second impellers to pump blood of a subject, by driving the first and second impellers to rotate. The blood pumps is configured such that (a) the first and second impellers are shaped differently from each other when the first and second impellers are in non-radially-constrained configurations, (b) the first and second impellers are sized differently from each other when the first and second impellers are in non-radially-constrained configurations, and/or (c) the first and second impellers are driven by the motor to rotate under respective rotation conditions that are different from each other. Other applications are also described.

Apparatus and methods are described including a blood pump that includes a catheter, a first impeller disposed on the catheter, and a second impeller disposed on the catheter, proximally to the first impeller. A motor drives the first and second impellers to pump blood of a subject, by driving the first and second impellers to rotate. The blood pumps is configured such that (a) the first and second impellers are shaped differently from each other when the first and second impellers are in non-radially-constrained configurations, (b) the first and second impellers are sized differently from each other when the first and second impellers are in non-radially-constrained configurations, and/or (c) the first and second impellers are driven by the motor to rotate under respective rotation conditions that are different from each other. Other applications are also described.

Apparatus and methods are described including a catheter, and first and second impellers configured to be inserted into a subject's body via the catheter, the first and second impellers being disposed in series with each other. A first impeller cage is disposed around the first impeller, and a second impeller cage is disposed around the second impeller. A sleeve extends longitudinally along more than 50 percent of a distance between the first and second impellers. Other applications are also described.

Apparatus and methods are described including a catheter, and first and second impellers configured to be inserted into a subject's body via the catheter, the first and second impellers being disposed in series with each other. A first impeller cage is disposed around the first impeller, and a second impeller cage is disposed around the second impeller. A sleeve extends longitudinally along more than 50 percent of a distance between the first and second impellers. Other applications are also described.

Methods and devices for supporting circulation. The methods may include positioning a blood pump in the arterial vasculature or the venous vasculature. The methods may include positioning a pump portion of the blood pump in a descending aorta, an inferior vena cava, a renal artery, and/or a renal vein. The methods include delivering a pump portion of a blood pump to a target location and rotating one or more impellers to move blood through the pump portion.

A blood pump-oxygenator system comprises at least one blood pump, an oxygenator, inflow and outflow cannulas, connected to form a closed series circuit operable as a cardiopulmonary bypass system for extracorporeal processing of the patient's blood. The blood pump conveys blood through the circuit from the patient into the inflow cannula, through the oxygenator and out of the outflow cannula back into the patient. A manifold is connected between the inflow and outflow cannulas so blood passes through the manifold, wherein the manifold accommodates the blood pump and the oxygenator to form a recirculation loop configured to recirculate at least part of the blood in the circuit so the blood passes over the oxygenator multiple times. An extra blood pump is positioned at the outflow cannula to deliver a set volume to the patient, controllable independently from the blood pump that circulates the blood in the manifold including the oxygenator.