aluminum a preferred shape memory alloy is nickel titanium shape memory alloys of nickel titanium in tubing form may be obtained from advanced cardiovascular systems inc santa clara calif the reinforcing member 28 surrounds the core 22 from the proximal end of the drive shaft 20 to the distal end of the drive shaft 20 the reinforcing member 28 is attached to the core 22 at least at two points the attachment is made by solder welding epoxy or other suitable method with reference to fig2 there is shown a first attachment point 30 at one end of the composite drive shaft 20 a second attachment is made at a second attachment point 32 at the opposite end of the drive shaft 20 the attachment of the core 22 and the reinforcing member 28 has the effect of combining the axial and torsional characteristics of the core 22 and the reinforcing member 28 the result is such that the composite drive shaft 20 behavior is improved as will be explained below with reference to fig2 4 and fig1 the elastic core 22 is generally an elongated cylinder the reinforcing member 28 is wound helically around the core 22 in the form of a spring as illustrated in fig1 4 a coating 34 of polymeric material such as polyethylene or the like is applied to the core 22 and reinforcing member 28 the coating 34 provides two functions first the coating 34 forms a smooth surface for providing low surface friction for sliding in a catheter not shown second the coating 34 is applied to penetrate and impregnate the interstices 36 depicted in fig5 and 7 between the reinforcement member 28 and the core 22 this penetration and impregnation binds the core 22 and member 28.