Distal tip element for blood pump

#Some applications of the present invention generally relate to medical apparatus. Specifically, some applications of the present invention relate to a ventricular assist device and methods of use thereof.

#Ventricular assist devices are mechanical circulatory support devices designed to assist and unload cardiac chambers in order to maintain or augment cardiac output. They are used in patients suffering from a failing heart and in patients at risk for deterioration of cardiac function during percutaneous coronary interventions. Most commonly a left-ventricular assist device is applied to a defective heart in order to assist left-ventricular functioning. In some cases, a right-ventricular assist device is used in order to assist right-ventricular functioning. Such assist devices are either designed to be permanently implanted or mounted on a catheter for temporary placement.

#In accordance with some applications of the present invention, a ventricular assist device includes an impeller disposed upon an axial shaft, with a frame disposed around the impeller. The ventricular assist device typically includes a tube, which traverses the subject's aortic valve, such that a proximal end of the tube is disposed in the subject's aorta and a distal end of the tube is disposed within the subject's left ventricle. The impeller, the axial shaft and the frame are disposed within a distal portion of the tube inside the subject's left ventricle. Typically, the impeller is configured to pump blood from the left ventricle into the aorta by rotating. The tube typically defines one or more blood inlet openings at the distal end of the tube, via which blood flows into the tube from the left ventricle, during operation of the impeller. For some applications, the proximal portion of the tube defines one or more blood outlet openings, via which blood flows from the tube into the ascending aorta, during operation of the impeller.

#FIGS. 1A and 1B are schematic illustrations of a ventricular assist device, a distal end of which is disposed in a subject's left ventricle, in accordance with some applications of the present invention;

#FIGS. 2A, 2B, and 2C are schematic illustrations of a pump portion of a ventricular assist device, in accordance with some applications of the present invention;

#FIGS. 3A, 3B and, 3C are schematic illustrations of an impeller of a ventricular assist device, in accordance with some applications of the present invention;

#Reference is now made to FIGS. 1A and 1B, which are schematic illustrations of a ventricular assist device 20, a distal end of which is disposed in a subject's left ventricle 22, in accordance with some applications of the present invention. The ventricular assist device includes a tube 24, which traverses an aortic valve 26 of the subject, such that a proximal end 28 of the tube is disposed in an aorta 30 of the subject and a distal end 32 of the tube is disposed within left ventricle 22. Tube 24 (which is sometimes referred to herein as a “blood-pump tube”) is typically an elongate tube, an axial length of the tube typically being substantially larger than its diameter. The scope of the present invention includes using the apparatus and methods described herein in anatomical locations other than the left ventricle and the aorta. Therefore, the ventricular assist device and/or portions thereof are sometimes referred to herein (in the specification and the claims) as a blood pump.

#As shown in FIG. 1B, which shows steps in the deployment of the ventricular assist device in the left ventricle, typically the distal end of the ventricular assist device is guided to the left ventricle over a guidewire 10. During the insertion of the distal end of the device to the left ventricle, a delivery catheter 143 is disposed over the distal end of the device. Once the distal end of the device is disposed in the left ventricle, the delivery catheter is typically retracted to the aorta, and the guidewire is withdrawn from the subject's body. The retraction of the delivery catheter typically causes self-expandable components of the distal end of the device to assume non-radially-constrained configurations, as described in further detail hereinbelow. Typically, the ventricular assist device is inserted into the subject's body in order to provide an acute treatment to the subject. For some applications, in order to withdraw the left ventricular device from the subject's body at the end of the treatment, the delivery catheter is advanced over the distal end of the device, which causes the self-expandable components of the distal end of the device to assume radially-constrained configurations. Alternatively or additionally, the distal end of the device is retracted into the delivery catheter which causes the self-expandable components of the distal end of the device to assume radially-constrained configurations.

#Reference is also made to FIGS. 2A, 2B, and 2C, which are schematic illustrations of a blood pump portion 27 of ventricular assist device 20, in accordance with some applications of the present invention. Typically, an impeller 50 is disposed within a distal portion 102 of tube 24 and is configured to pump blood from the left ventricle into the aorta by rotating. The tube typically defines one or more blood inlet openings 108 at the distal end of the tube, via which blood flows into the tube from the left ventricle, during operation of the impeller. For some applications, the proximal portion of the tube defines one or more blood outlet openings 109, via which blood flows from the tube into the ascending aorta, during operation of the impeller.