Collapsible and self-expanding cannula for a percutaneous heart pump and method of manufacturing

Abstract

An expandable cannula for a percutaneous heart pump includes a substantially open proximal end, a substantially open distal end and an elongate central portion disposed between the proximal end and the distal end. The elongate central portion has an inner surface and an opposing outer surface. The expandable cannula is made of a shape memory alloy having an austenite finish temperature Af that is at or below the body temperature of a human patient.

What is claimed is: 
     
         1 . An expandable cannula for a percutaneous heart pump, the expandable cannula comprising:
 a substantially open proximal end;   a substantially open distal end; and   an elongate central portion disposed between the proximal end and the distal end, the elongate central portion having an inner surface and an opposing outer surface;   wherein the expandable cannula comprises a shape memory alloy having an austenite finish temperature A f  that is at or below the body temperature of a human patient.   
     
     
         2 . The expandable cannula according to  claim 1 , wherein A f  is 37° C. 
     
     
         3 . The expandable cannula according to  claim 2 , wherein A f  is from 5° C. to 30° C. 
     
     
         4 . The expandable cannula according to  claim 2 , wherein A f  is from 10° C. and 25° C. 
     
     
         5 . The expandable cannula according to  claim 2 , wherein A f  is from 10° C. to 20° C. 
     
     
         6 . The expandable cannula according to  claim 1 , wherein the shape memory alloy is selected from the group consisting of nickel-titanium (nitinol), copper-zinc, copper-zinc-aluminum, copper-aluminum-nickel, and gold-cadmium. 
     
     
         7 . The expandable cannula according to  claim 1 , wherein the elongate central portion has an outer diameter of approximately 3.5 mm when the shape memory alloy is in a martensite phase. 
     
     
         8 . The expandable cannula according to  claim 1 , wherein the elongate central portion has an outer diameter of approximately 7 mm when the shape memory alloy is at or above the A f  temperature. 
     
     
         9 . The expandable cannula according to  claim 1 , wherein the elongate central portion comprises a cage or mesh structure. 
     
     
         10 . The expandable cannula according to  claim 9 , wherein the elongate central portion is encapsulated in a fluid impermeable membrane. 
     
     
         11 . The expandable cannula according to  claim 9 , wherein the cage or mesh structure is at least one of a braided mesh, a woven mesh, or a laser-cut interconnected maze-like pattern. 
     
     
         12 . The expandable cannula according to  claim 1 , wherein the substantially open proximal portion and the substantially open distal portion each comprise a plurality of struts. 
     
     
         13 . The expandable cannula according to  claim 12 , wherein the struts are comprised of the shape memory alloy. 
     
     
         14 . A percutaneous heart pump, comprising:
 an expandable cannula comprising a substantially open proximal end, a substantially open distal end and an elongate central portion disposed between the proximal end and the distal end, the elongate central portion having an inner surface and an opposing outer surface, at least the elongate central portion comprising a shape memory alloy having an austenite finish temperature A f  that is at or below the body temperature of a human patient; and   a collapsible impeller rotatably fixed within the elongate central portion of the cannula.   
     
     
         15 . The percutaneous heart pump according to  claim 14 , wherein A f  is 37° C. 
     
     
         16 . The percutaneous heart pump according to  claim 15 , wherein the elongate central portion has an outer diameter of approximately 7 mm when the shape memory alloy is at or above the A f  temperature. 
     
     
         17 . The percutaneous heart pump according to  claim 16 , wherein the elongate central portion has an outer diameter of approximately 3.5 mm when the shape memory alloy is in a martensite phase. 
     
     
         18 . The percutaneous heart pump according to  claim 14  further comprising a fluid impermeable membrane that encapsulates the elongate central portion of the cannula, the fluid impermeable membrane selected from the group consisting of a thermoplastic, segmented polyurethane block copolymer, a poly(ether-b-amide) copolymer, poly(ether ester) block copolymer, a functionalized olefinic thermoplastic elastomer having polar functional groups, a styrenic thermoplastic elastomer functionalized by polar functional groups, and combinations thereof, wherein the polar functional groups are selected from the group consisting of maleic anhydride, acrylate, epoxy, amine, and combinations thereof. 
     
     
         19 . The percutaneous heart pump according to  claim 18 , wherein the fluid impermeable layer comprises at least two layers. 
     
     
         20 . The percutaneous heart pump according to  claim 19 , wherein the at least two layers are thermally bonded to the elongate central portion.