Methods for crimping a polymeric scaffold to a delivery balloon and achieving stable mechanical properties in the scaffold after crimping
First Claim
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1. A method for crimping a balloon-expanded scaffold to a balloon, comprising the steps of:
- providing a tube comprising PLLA-(Poly(L-lactide)) characterized by a glass transition temperature (TG) range having a lower limit of TG-low;
radially expanding the tube to increase its radial stiffness;
forming the scaffold from the radially-expanded tube; and
crimping the scaffold to the balloon while the scaffold has a crimping temperature of between about TG-low to about 5 degrees Celsius above TG-low including maintaining a pressure in the balloon as the scaffold diameter is being reduced in size.
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Abstract
A medical device-includes a polymer scaffold crimped to a catheter having an expansion balloon. The scaffold is crimped to the balloon by a process that includes inflating the delivery balloon during a diameter reduction to improve scaffold retention. A crimping temperature is maintained at about the onset of glass transition of the polymer material to facilitate more rapid stabilization of mechanical properties in the scaffold following crimping.
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Citations
21 Claims
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1. A method for crimping a balloon-expanded scaffold to a balloon, comprising the steps of:
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providing a tube comprising PLLA-(Poly(L-lactide)) characterized by a glass transition temperature (TG) range having a lower limit of TG-low; radially expanding the tube to increase its radial stiffness; forming the scaffold from the radially-expanded tube; and crimping the scaffold to the balloon while the scaffold has a crimping temperature of between about TG-low to about 5 degrees Celsius above TG-low including maintaining a pressure in the balloon as the scaffold diameter is being reduced in size. - View Dependent Claims (2, 3, 4, 5)
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6. A method for making a medical device comprising the steps of:
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providing a balloon having a deployed diameter when the balloon is inflated; providing a scaffold comprising a polymer having a lower range of a glass transition temperature (TG-low), the scaffold having a pre-crimp diameter that is equal to or larger than the deployed diameter; crimping the scaffold to the balloon while the scaffold has a temperature of between about TG-low to about 5 degrees Celsius above TG-low, the crimping step including the steps of (a) reducing the scaffold diameter from the pre-crimp diameter to a first diameter, (b) maintaining the first diameter for a first dwell period to allow for stress relaxation in the polymer, (c) reducing the scaffold diameter from the first diameter to a second diameter, and (d) maintaining the second diameter for a second dwell period to allow for stress relaxation in the polymer. - View Dependent Claims (7, 8, 9, 10, 11, 12)
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13. A method for crimping, comprising the steps of:
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providing a scaffold comprising a polymer characterized by a glass transition temperature (TG) range having a lower limit of TG-low; and crimping the scaffold to a balloon while the scaffold has a crimping temperature of between about TG-low and about 5°
C. above TG-low to accelerate a stress relaxation in the crimped scaffold, including the steps of;crimping the scaffold from a first diameter to a second diameter, after crimping to the second diameter and before crimping to a final crimp diameter, removing the scaffold from the crimping device, returning the scaffold to the crimping device, wherein the scaffold is aligned on the balloon when the scaffold is returned to the crimping device, and crimping the scaffold from the second diameter to the final crimp diameter. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21)
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Specification