Blood pump housing
Apparatus and methods are described for manufacturing a housing for an impeller of a blood pump. A mandrel is placed inside an inner lining, with a central cylindrical portion of a frame disposed around the inner lining, the mandrel being shorter than a length of the inner lining. A portion of an elongate tube is placed around at least a portion of the frame. The inner lining, the frame and the portion of the elongate tube are heated, via the mandrel, and, while heating the inner lining, the frame, and the portion of the elongate tube, pressure is applied from outside the portion of the elongate tube, such as to cause the portion of the elongate tube to become coupled to the frame. Other applications are also described.
1 . A method, comprising:
manufacturing a housing for an impeller of a blood pump by:
placing a mandrel inside an inner lining, with a central cylindrical portion of a frame disposed around the inner lining, the central cylindrical portion of the frame including struts that define a generally cylindrical shape,
wherein the mandrel is shorter than a length of the inner lining;
placing a portion of an elongate tube around at least a portion of the frame, the elongate tube including a proximal portion that defines at least one blood outlet opening;
while the portion of the elongate tube is disposed around at least the portion of the frame, heating the inner lining, the frame and the portion of the elongate tube, via the mandrel; and
while heating the inner lining, the frame, and the portion of the elongate tube, applying pressure from outside the portion of the elongate tube, such as to cause the portion of the elongate tube to become coupled to the frame.
2 . The method according to claim 1 , wherein struts of the central cylindrical portion of the frame define cells which are configured such that, in a non-radially-constrained configuration of the frame, a width of each of each of the cells within the central cylindrical portion of the frame as measured around a circumference of the central cylindrical portion of the frame is less than 2 mm.
3 . The method according to claim 1 , wherein applying pressure from outside the portion of the elongate tube, while heating the inner lining, the frame and the portion of the elongate tube, comprises causing the portion of the elongate tube to conform with a structure of the struts of the frame.
4 . The method according to claim 1 , wherein placing the mandrel inside the inner lining comprises placing the mandrel within the inner lining such that margins are left outside of the mandrel at each end of the inner lining.
5 . The method according to claim 4 , wherein placing the mandrel within the inner lining such that margins are left outside of the mandrel at each end of the inner lining comprises preventing the mandrel from coming into direct contact with the frame or the pump-outlet tube, thereby protecting the pump-outlet tube from being overheated and becoming damaged by the heating of the mandrel.
6 . The method according to claim 1 , further comprising, prior to placing the mandrel inside the inner lining:
treating the frame in order to enhance bonding between an inner surface of the frame and the inner lining; and
coupling the inner lining to the inner surface of the frame along at least a portion of the central cylindrical portion of the frame.
7 . The method according to claim 6 , wherein coupling the inner lining to the inner surface of the frame along at least a portion of the central cylindrical portion of the frame comprises coupling the inner lining to the inner surface of the frame along at least a portion of the central cylindrical portion of the frame, such that the inner lining has a substantially circular cross section.
8 . The method according to claim 6 , wherein coupling the inner lining to the inner surface of the frame along at least a portion of the central cylindrical portion of the frame comprises coupling the inner lining to the inner surface of the frame along at least a portion of the central cylindrical portion of the frame, such that the inner lining provides a smooth inner surface to the portion of the central cylindrical portion of the frame to which the inner lining is coupled.
9 . The method according to claim 6 , wherein coupling the inner lining to the inner surface of the frame along at least a portion of the central cylindrical portion of the frame comprises avoiding air bubbles, folds, and other discontinuities in a smoothness of a surface provided by the inner lining.
10 . The method according to claim 6 , wherein treating the frame in order to enhance bonding between the inner surface of the frame and the inner lining comprises applying a plasma treatment to the frame.
11 . The method according to claim 6 , wherein coupling the inner lining to the inner surface of the frame along at least a portion of a central cylindrical portion of the frame comprises:
placing the inner lining over a mandrel;
placing the frame over the inner lining; and
applying pressure via a heat shrinking process.
12 . The method according to claim 6 , wherein treating the frame in order to enhance bonding between the inner surface of the frame and the inner lining comprises dipping the frame in a solution that contains the material from which the inner lining is made.
13 . The method according to claim 12 , wherein the inner lining comprises polyurethane and wherein dipping the frame in the solution comprises dipping the frame in a polyurethane solution.
14 . The method according to claim 6 , wherein treating the frame in order to enhance bonding between the inner surface of the frame and the inner lining comprises spraying the inner surface of the portion of the central cylindrical portion of the frame with a solution that contains the material from which the inner lining is made.
15 . The method according to claim 14 , wherein the inner lining comprises polyurethane and wherein spraying the inner surface of the portion of the central cylindrical portion of the frame comprises spraying the inner surface of the portion of the central cylindrical portion of the frame with a polyurethane solution.
16 . The method according to claim 6 , wherein treating the frame in order to enhance bonding between the inner surface of the frame and the inner lining comprises dipping the frame in a coupling agent that has at least two functional groups that are configured to bond respectively with the frame and with a material form which the inner lining is made.
17 . The method according to claim 16 , wherein the inner lining comprises polyurethane and wherein dipping the frame in the coupling agent comprises dipping the frame in the coupling agent comprises dipping the frame in a silane solution.