| 摘要 |
A catheter includes a spring having a plurality of convolutions disposed along a longitudinal axis, and a first modulus. A sheath overlying the spring engages the convolutions of the spring and imparts to the spring axial compressive stresses which increase the modulus of the spring. The catheter can be manufactured by inserting the spring into a tube of Hytrel TM material, stretching the tube at a transition region which advances along thhe tube causing the tube to neck down onto the spring. The stretching develops internal stresses which are utimately imparted to the spring thereby increasing the modulus of the catheter.
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