| http://www.w3.org/ns/prov#value | - U.S. Pat. No. 3,757,768, to de Toledo, shows a unitary, combined spring guide-catheter that includes an inner wall portion formed as a continuous helical spring with the helices in contact with each other and an outer wall portion formed from an inert plastic material enclosing the spring in such a manner as to become firmly bonded to the spring while having its outer surface smooth.
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