Apparatus and methods are described including an impeller (50) that includes a proximal bushing (64) and a distal bushing (58). Two or more helical elongate elements (52) extend from the proximal bushing (64) to the distal bushing (58), and an axial structure (54) is disposed inside of the two or more helical elongate elements (52), and along an axis around which the helical elongate elements (52) wind. The impeller (50) includes an impeller-overexpansion-prevention element (72). The impeller-overexpansion-prevention element is a single integrated structure that includes a ring (73) disposed around the axial structure (54), and a plurality of elongate elements (67) each of the elongate elements (67) extending from the ring to a respective helical elongate element (52) and being coupled to the respective helical elongate element (52) so as to prevent radial expansion of the impeller (50). Other applications are also described.

Apparatus and methods are described including an impeller (50) that includes a proximal bushing (64) and a distal bushing (58). Two or more helical elongate elements (52) extend from the proximal bushing (64) to the distal bushing (58), and an axial structure (54) is disposed inside of the two or more helical elongate elements (52), and along an axis around which the helical elongate elements (52) wind. The impeller (50) includes an impeller-overexpansion-prevention element (72). The impeller-overexpansion-prevention element is a single integrated structure that includes a ring (73) disposed around the axial structure (54), and a plurality of elongate elements (67) each of the elongate elements (67) extending from the ring to a respective helical elongate element (52) and being coupled to the respective helical elongate element (52) so as to prevent radial expansion of the impeller (50). Other applications are also described.

This disclosure is directed to systems and techniques for detecting changes in patient health based upon monitoring patient sleep activities. One example medical system comprises one or more sensors configured to sense patient activity; sensing circuitry configured to provide patient activity data based on the sensed patient activity; and processing circuitry configured to: determine, from the patient activity data, for each of a plurality of intervals, a respective activity classification, wherein each activity classification indicates whether the patient activity data during the interval satisfies at least one predetermined criterion indicative of patient movement; for each of a plurality of timeslots, determine a number of intervals that satisfy the at least one predetermined criterion, each timeslot including a consecutive subset of the plurality of intervals; and identify transitions between an inactive state and an active state of the patient based on the determined numbers of intervals within the plurality of timeslots.

A heart pump including a housing forming a cavity including at least one inlet and at least one outlet, an impeller provided within the cavity, the impeller including vanes for urging fluid from the inlet to the outlet upon rotation of the impeller, a drive that rotates the impeller within the cavity, a magnetic bearing including at least one bearing coil that controls an axial position of the impeller within the cavity and a controller. The controller includes an electronic processing device that monitors changes in a bearing indicator in response to a perturbation in blood flow, the bearing indicator being at least partially indicative of operation of the magnetic bearing and controls the drive to thereby selectively change a rotational speed of the impeller at least partially in accordance with changes in the bearing indicator.

Systems and methods are provided herein for estimating a position of a heart pump system in a patient. The system receives first data indicative of a time-varying motor current during a first time period. The motor current corresponds to an amount of current delivered to a motor, while the heart pump system is operating in the patient. The system receives second data indicative of a time-varying differential pressure during the first time period. The differential pressure is indicative of a position of the heart pump system relative to patient's heart. The system receives third data indicative of time-varying motor current during a second time period, and determines an estimate of differential pressure during the second period of time from the third data and a relationship between the first data and the second data. The estimate is usable to predict the position of the heart pump system in the patient.

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 generally 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. Other applications are also described.

Apparatus and methods are described including a ventricular assist device that includes a frame having struts that define a plurality of cells. In its non-radially-constrained configuration, the frame includes a generally cylindrical portion. A tube defines blood outlet openings, and a portion of the tube is disposed outside the frame and is coupled to the generally cylindrical portion of the frame, such that the portion of the tube conforms with a structure of struts of the frame. An inner lining is coupled to an inside of the generally cylindrical portion of the frame, such as to provide the generally cylindrical portion of the frame with a smooth inner surface. An impeller is disposed at least partially inside the generally cylindrical portion of the frame and is configured to pump blood through the tube and out of the one of more blood outlet openings. Other applications are also described.

Apparatus and methods are described including a ventricular assist device configured to assist ventricular functioning of a subject. The ventricular assist device includes an impeller and a frame disposed around the impeller. An axial shaft extends from a proximal end of the frame to a distal end of the frame, the impeller being coupled to the axial shaft. The axial shaft includes a proximal portion and a distal portion, which are coupled to each other via a joint. The proximal portion and the distal portion of the axial shaft are configured to flex with respect to each other via the joint. Other applications are also described.

Apparatus and methods are described including a ventricular assist device that includes a blood pump configured to be placed inside a left ventricle of a subject and to pump blood from the subject's left ventricle to an aorta of the subject. A blood pressure sensor measures aortic pressure of the subject. A computer processor varies a flow rate that is that is generated by the blood pump, and determines a relationship between arterial pulsatility of the subject and the flow rate that is generated by the blood pump, based upon aortic pressure that is measured by the blood pressure sensor as the flow rate that is generated by the blood pump is varied. The computer processor estimates native cardiac output of the subject at least partially based upon the relationship. Other applications are also described.

Apparatus and methods are described including a ventricular assist device that includes a blood pump configured to be placed inside a left ventricle of a subject and to pump blood from the subject's left ventricle to an aorta of the subject. A blood pressure sensor measures aortic pressure of the subject. A computer processor varies a flow rate that is that is generated by the blood pump, and determines a relationship between arterial pulsatility of the subject and the flow rate that is generated by the blood pump, based upon aortic pressure that is measured by the blood pressure sensor as the flow rate that is generated by the blood pump is varied. The computer processor estimates native cardiac output of the subject at least partially based upon the relationship. Other applications are also described.