Apparatus and methods are described for use with a tributary vessel of a subject that supplies a vein of the subject. Blood within the tributary vessel is mechanically isolated into a compartment that is separated from blood within the vein. Blood flow from the tributary vessel to the vein is controlled by pumping blood from the compartment to the vein. Other applications are also described.

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.

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.

Apparatus and methods are described including a blood pump (24) configured to be placed inside a blood vessel of a in subject, the blood pump including an impeller (28) configured to pump blood by rotating. A support cage (254) is shaped to define a narrow portion (256) that is configured to be disposed around the impeller, and to maintain a separation between a wall of the blood vessel and the impeller, and a radial extension (258) from the narrow portion of the support cage that extends radially outward with respect to the narrow portion of the support cage, the radial extension being configured to substantially maintain a longitudinal axis of the impeller in alignment with a local longitudinal axis of the blood vessel by contacting the wall of the blood vessel. Other applications are also described.

Apparatus and methods are described including a blood pump that includes an axial shaft, an impeller disposed on the axial shaft, a frame disposed around the impeller, and a motor disposed outside a subject's body, and configured to drive the impeller to pump blood from a distal end of the impeller to a proximal end of the impeller. A drive cable extends from outside the subject's body to the axial shaft, and is configured to impart rotational motion from the motor to the impeller by rotating. The drive cable is held in a preloaded state with respect to the frame, such that initiation of pumping of blood by rotation of the impeller does not cause the drive cable to axially elongate. Other applications are also described.

Apparatus and methods are described including a blood pump that includes an axial shaft, an impeller disposed on the axial shaft, a frame disposed around the impeller, and a motor disposed outside a subject's body, and configured to drive the impeller to pump blood from a distal end of the impeller to a proximal end of the impeller. A drive cable extends from outside the subject's body to the axial shaft, and is configured to impart rotational motion from the motor to the impeller by rotating. The drive cable is held in a preloaded state with respect to the frame, such that initiation of pumping of blood by rotation of the impeller does not cause the drive cable to axially elongate. Other applications are also described.

A blood pump is described that includes an impeller having proximal and distal bushings, at least one helical elongate element, a spring that is disposed inside of the helical elongate element and along an axis around which the helical elongate element winds, and a film of material supported between the helical elongate element and the spring. A frame is disposed around the impeller. A flexible elongate element extends radially from the spring to the helical elongate element, and maintains the helical elongate element within a given distance from the spring, to thereby maintain a gap between an outer edge of a blade of the impeller and an inner surface of the frame, during rotation of the impeller. Other applications are also described.

A blood pump is described that includes an impeller having proximal and distal bushings, at least one helical elongate element, a spring that is disposed inside of the helical elongate element and along an axis around which the helical elongate element winds, and a film of material supported between the helical elongate element and the spring. A frame is disposed around the impeller. A flexible elongate element extends radially from the spring to the helical elongate element, and maintains the helical elongate element within a given distance from the spring, to thereby maintain a gap between an outer edge of a blade of the impeller and an inner surface of the frame, during rotation of the impeller. Other applications are also described.

Various systems and methods are provided for reducing pressure at an outflow of a duct such as the thoracic duct or the lymphatic duct. A catheter system can include a catheter shaft configured to be at least partially implantable within a patient's vein, a flexible membrane attached to the catheter shaft, the flexible membrane being a collapsible, tube-like member having a lumen extending therethrough, and a single selectively deployable restriction member formed over a portion of the flexible membrane at substantially a midpoint between a proximal end of the flexible membrane and a distal end of the flexible membrane, the restriction member being configured to control a size of the lumen so as to direct a controlled volume of fluid from an upstream side of the restriction member to a downstream side the restriction member.

Apparatus and methods are described including a ventricular assist device that includes an impeller configured to be placed inside a subject's left ventricle. A frame is disposed around the impeller, the frame defining generally-cylindrical central portion, and a proximal conical portion that widens from a proximal end of the frame to a proximal end of the generally-cylindrical central portion. A motor drives the impeller to pump blood from the left ventricle to the subject's aorta, by rotation of the impeller. The impeller is configured to be disposed at least partially within the proximal conical portion of the frame during at least some of a time during which the impeller rotates. Other applications are also described.