Frame for blood pump
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.
1. An apparatus for use with a delivery catheter, the apparatus comprising: a blood pump comprising: an impeller configured to pump blood through a subject's body; a frame disposed around the impeller, the impeller and frame defining non-radially-constrained configurations in which the impeller is configured to pump blood within the subject's body, and defining radially-constrained configurations in which the impeller and frame are inserted and removed from the subject's body using a delivery catheter, the frame defining 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 being configured such that, in response to a distal end of the delivery catheter and the frame being moved into overlapping positions with respect to each other, the frame is configured to assume its radially-constrained configuration by becoming axially elongated, and the frame is configured to cause the impeller to assume its radially-constrained configuration by causing the impeller to become axially elongated wherein, in its radially-non-constrained configuration, the frame defines a proximal conical portion, a distal conical portion, and a cylindrical portion between the proximal conical portion and the distal conical portion, wherein a density of the struts increases from the proximal conical portion to the cylindrical portion, and from the distal conical portion to the cylindrical portion, and wherein during operation of the blood pump, the impeller is configured to move with respect to the frame, and a range of movement of the impeller is such that at least a portion of the impeller is disposed within the proximal conical portion of the frame during at least some of the operation of the blood pump, and at least a portion of the impeller is disposed within the cylindrical portion of the frame during at least some of the operation of the blood pump.
2. The apparatus according to claim 1 , wherein the structure of the struts of the frame is configured such that, in response to a distal end of the delivery catheter and the frame being moved into overlapping positions with respect to each other, the frame is configured to assume its radially-constrained configuration by becoming axially elongated, and is configured to cause the impeller to assume its radially-constrained configuration by becoming axially elongated, by the pairs of struts that branch from the junctions being configured to pivot about the junction and move closer to each other such as to close.
3. The apparatus according to claim 1 , wherein, within the cylindrical portion of the frame, a strut density of the frame is constant.
4. The apparatus according to claim 1 , wherein throughout the operation of the blood pump, at a location at which a span of the impeller is at its maximum, the impeller is configured to be disposed within the cylindrical portion of the frame.
5. The apparatus according to claim 1 , wherein a width of each of the cells within the cylindrical portion as measured around a circumference of the cylindrical portion is less than 2 mm.
6. The apparatus according to claim 5 , wherein the width of each of the cells within the cylindrical portion as measured around the circumference of the cylindrical portion is between 1.4 mm and 1.6 mm.
7. The apparatus according to claim 5 , wherein the width of each of the cells within the cylindrical portion as measured around the circumference of the cylindrical portion is between 1.6 mm and 1.8 mm.