The disclosure relates to devices and methods for the treatment of edema using a purge-free system. The invention provides devices and methods useful for treating edema by means of an indwelling catheter that is placed in a blood vessel of a patient and used to pump blood to cause a decrease in pressure at an outlet of a lymphatic duct. The catheter pumps blood by means of an impeller but is purge-free in that the catheter does not include a system for purging or flushing catheter components with a purge fluid. The purge-free catheter avoids blood-related mechanical complications such as clotting or thrombosis by means of an impermeable sleeve or shroud that protects moving parts of the impeller drive system.

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. In a radially-non-constrained configuration of the frame, the frame defines a proximal conical portion and a cylindrical portion disposed distally to the proximal conical portion. The blood pump is configured such that such that, during at least some of the operation of the blood pump, at least a portion of the impeller is disposed within the proximal conical portion of the frame. 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. In a radially-non-constrained configuration of the frame, the frame defines a proximal conical portion and a cylindrical portion disposed distally to the proximal conical portion. The blood pump is configured such that such that, during at least some of the operation of the blood pump, at least a portion of the impeller is disposed within the proximal conical portion of the frame. Other applications are also described.

A system for measuring of arterial and venous blood constituent concentration based first on measuring cardiac blood flow balance parameter between the right chamber of the heart and the left chamber of the heart, which includes a sensor device for measuring one of blood pressure and blood flow rate and blood constituent concentration of a patient so as to generate an arterial pulse signal. A processing unit is responsive to the arterial pulse signal for generating full arterial pulse plethysmography waveforms, arterio-venous pulse plethysmography waveforms, and balance parameters. A computational device that is responsive to plethysmography waveforms generating a plurality of state space linear transfer functions by applying system identification between plethysmography waveforms at various wavelengths representing a plurality of models of the blood constituent concentration, including oxygen, carbon dioxide, hemoglobin, and glucose, and displaying related useful information.

Apparatus and methods are described including a left-ventricular assist device configured to assist left-ventricular functioning of a subject. The left-ventricular assist device includes a frame, a rigid axial shaft extending from a proximal end of the frame to a distal end of the frame, and an impeller disposed on the rigid axial shaft. A motor is disposed outside the subject's body, and a flexible drive cable extends from outside the subject's body to the axial shaft. The drive cable imparts rotational motion from the motor to the rigid axial shaft, to thereby rotate the impeller. Other applications are also described.

Apparatus and methods are described including a left-ventricular assist device configured to assist left-ventricular functioning of a subject. The left-ventricular assist device includes a frame, a rigid axial shaft extending from a proximal end of the frame to a distal end of the frame, and an impeller disposed on the rigid axial shaft. A motor is disposed outside the subject's body, and a flexible drive cable extends from outside the subject's body to the axial shaft. The drive cable imparts rotational motion from the motor to the rigid axial shaft, to thereby rotate the impeller. Other applications are also described.

Apparatus and methods are described including a left-ventricular assist device. A pump pumps blood from the subject's left ventricle to the subject's aorta, via a tube. A distal-tip element is disposed distally to the pump and defines a straight proximal portion that defines a longitudinal axis, and a curved distal portion that is shaped such as to curve in a first direction with respect to the longitudinal axis of the straight proximal portion before passing through an inflection point and curving in a second direction with respect to the longitudinal axis of the straight proximal portion, such that the curved distal portion defines a bulge on one side of the longitudinal axis of the straight proximal portion. Other applications are also described.

Apparatus and methods are described including a left-ventricular assist device. A pump pumps blood from the subject's left ventricle to the subject's aorta, via a tube. A distal-tip element is disposed distally to the pump and defines a straight proximal portion that defines a longitudinal axis, and a curved distal portion that is shaped such as to curve in a first direction with respect to the longitudinal axis of the straight proximal portion before passing through an inflection point and curving in a second direction with respect to the longitudinal axis of the straight proximal portion, such that the curved distal portion defines a bulge on one side of the longitudinal axis of the straight proximal portion. Other applications are also described.

Apparatus and methods are described including a blood pump configured to be placed inside a subject's body. The blood pump includes an impeller, a frame disposed around the impeller, a distal-tip portion disposed distally with respect to the frame, and a valve disposed within the distal-tip portion. Other applications are also described.

Apparatus and methods are described including a blood pump configured to be placed inside a subject's body. The blood pump includes an impeller, a frame disposed around the impeller, a distal-tip portion disposed distally with respect to the frame, and a valve disposed within the distal-tip portion. Other applications are also described.