Apparatus and methods are described including a left-ventricular assist device that includes a tube configured to traverse a subject's aortic valve, with a distal portion of the tube within the subject's left ventricle. A frame disposed within the distal portion of the tube defines cells, and a width of each of the cells within a cylindrical portion of the frame is less than 2 mm. An inner lining lines at least some of the cylindrical portion of the frame. An impeller is disposed inside the frame such that a gap between an outer edge of the impeller and the inner lining is less than 1 mm. The impeller is stabilized with respect to the frame, such that, during rotation of the impeller, the gap between the outer edge of the impeller and the inner lining is maintained and is substantially constant. Other applications are also described.

Apparatus and methods are described including manufacturing an impeller by forming a structure having first and second bushings at proximal and distal ends that are connected to one another by at least one elongate element. The elongate element is made to radially expand and form a helical elongate element. An elastomeric material is coupled to the helical elongate element, such that the helical elongate element with the elastomeric material coupled thereto defines a blade of the impeller. The coupling is performed such that a layer of the material disposed around a radially outer edge of the helical elongate element forms the effective edge of the impeller blade. A step is performed to enhance bonding of the elastomeric material to the helical elongate element in a manner that does not cause a protrusion from the effective edge of the impeller blade. Other applications are also described.

Apparatus and methods are described including a blood pump that includes an impeller configured to pump blood through a subject's body, and a frame disposed around the impeller. The frame defines struts having a structure that is such that, as the frame transitions from a proximal end of the frame toward a center of the frame, the struts pass through junctions, at which the two struts branch from a single strut, in a Y-shape. The structure of the struts of the frame is configured such that, in response to a distal end of a delivery catheter and the frame being moved into overlapping positions with respect to each other, the frame assumes a radially-constrained configuration by becoming axially elongated, and the frame causes the impeller to assume a radially-constrained configuration by becoming axially elongated. Other applications are also described.

Apparatus and methods are described including manufacturing a housing for an impeller of a blood pump by placing an inner lining around a mandrel, placing a cylindrical portion of a frame around the inner lining, and placing a distal portion of an elongate tube around a portion of the frame. While the distal portion of the elongate tube is disposed around the portion of the frame, the inner lining, the frame, and the distal portion of the elongate tube are heated, via the mandrel, and pressure is applied from outside the distal portion of the elongate tube, such as to cause the distal portion of the elongate tube to conform with a structure of the struts of the frame, and to cause the inner lining and the distal portion of the elongate tube to become coupled to the frame. Other applications are also described.

Apparatus and methods are described including coupling a rigid tube to a drive cable that comprises a plurality of coiled wires, by placing ends of the drive cable and the rigid tube at a given location within a butt-welding overtube. The ends of the drive cable and the rigid tube are visible when they are disposed at the given location within the butt-welding overtube, via a window defined by the butt-welding overtube. The placement of the drive cable within the butt-welding overtube is such that a helical groove within a portion of the butt-welding overtube is disposed over the drive cable. Welding rings are formed around the butt-welding overtube. Other applications are also described.

A pressure differential across a blood pump and/or a flow rate of blood pumped by the blood pump is estimated based at least in part on impeller thrust load. A blood pump for a circulation assist system includes a housing forming a blood flow channel, an impeller, one or more support members coupled to the housing, a sensor, and a controller operatively coupled with the sensor. At least one of the one or more support members react a thrust load applied to the impeller by blood impelled through the blood flow channel by the impeller. The sensor generates output indicative of the magnitude of the thrust load. The controller is configured to process the sensor output to estimate at least one of a pressure differential across the blood pump and a flow rate of blood pumped by the blood pump.

A pump is provided for conveying body fluids, in particular blood, wherein the pump has a pump housing and a rotor mounted in the pump housing. The rotor comprises at least one sensor for detecting flow and/or movement parameters. Also provided is a method for operating the pump.

A heart pump including: a housing forming a cavity including: at least one inlet aligned with an axis of the cavity; and, at least one outlet provided in a circumferential outer wall of the cavity; an impeller provided within the cavity, the impeller including vanes for urging fluid from the inlet to the outlet; and, a drive for rotating the impeller in the cavity and wherein a flow path through the pump has a minimal cross-sectional area of at least 50 mm.sup.2.

Methods for operating a liquid pump having a rotor are provided for conveying liquids. The viscosity of the conveyed liquid, such as blood, may be determined while taking into account measured values of operating parameters of the pump. The pump may be operated in a predetermined region of a family of characteristic curves. The family of characteristic curves may link at least two operating parameters of the pump to each other, and, in the predetermined region, at least three parameters of the pump may be sensed and taken into account in order to determine the viscosity. Because of the operation in a predetermined region of a family of characteristic curves, the viscosity of the conveyed liquid can be determined in addition to the volumetric flow rate through the pump and the pressure difference across the pump when an appropriate selection is made from a sufficient number of sensed operating parameters.

Disclosed herein is an implantable blood pump assembly that includes a housing defining an inlet, an outlet, a flow path extending from the inlet to the outlet, and an internal compartment separated from the flow path. The blood pump assembly further includes a rotor positioned within the flow path and operable to pump blood from the inlet to the outlet, a stator positioned within the internal compartment and operable to drive the rotor, and an inlet conduit connected to the housing inlet and having a downstream end that has a reduced cross-sectional area that produces a localized region of high velocity blood flow. The blood pump assembly further includes at least one pressure sensor positioned between the inlet and the outlet and configured to detect a pressure of blood flowing through the flow path. The pressure sensor is located adjacent the downstream end of the inlet conduit.