METHODS FOR UNIFORM CRIMPING AND DEPLOYMENT OF A POLYMER SCAFFOLD
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Abstract
A medical device-includes a scaffold crimped to a catheter having an expansion balloon. The scaffold is crimped to the balloon by a process that includes one or more balloon pressurization steps. The balloon pressurization steps are selected to enhance scaffold retention to the balloon while retaining, at least partially, the original balloon folds as the balloon is pressurized and de-pressurized within a crimper head. By at least partially retaining the original balloon folds, a uniformity of scaffold expansion by the balloon is improved.
11 Citations
29 Claims
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1-19. -19. (canceled)
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20. A method of crimping, comprising:
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using a balloon having a nominal balloon diameter; using a scaffold having a pre-crimp diameter and a network of rings having struts and crowns, and the rings are connected by links, wherein the rings and links are made from a polymeric material, and the pre-crimp diameter is larger than the nominal balloon diameter; and crimping the scaffold to the balloon to produce a crimped scaffold having a minimum crimped diameter (Dmin), wherein the scaffold is plastically deformed onto the balloon surface to form a fit that resists dislodgement of the scaffold from the balloon surface, and Dmin is equal to or less than a value derived from equation 1 for struts having an essentially square cross-section or from equation 2 for struts having a trapezoidal cross-section;
(Σ
Swi+Σ
Crj+Σ
Lwk)*(π
)−
1+2*WT
(equation
1)
(Σ
Swi+Σ
Crj+Σ
Lwk)*(π
)−
1
(equation
2)wherein Σ
Swi (i=1 . . . n) is the sum of n ring struts having width Swi;Σ
Crj (j=1 . . . m) is the sum of m crown inner radii having radii Crj (times
2);Σ
Lwk (k=1 . . . p) is the sum of p links having width Lwk; andWT is a ring wall thickness. - View Dependent Claims (21, 22, 23, 24)
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25. A method of crimping, comprising:
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using a balloon having N pre-set folds and a nominal balloon diameter; using a scaffold having a pre-crimp diameter and a plurality of rings, wherein adjacent ring pairs are connected by links, wherein the rings and links are made from a polymeric material, each ring comprises a pair of struts connected at a crown, and the pre-crimp diameter is larger than the nominal balloon diameter; and using a crimping mechanism, plastically deforming the scaffold onto the balloon surface to form a fit that resists dislodgement of the scaffold from the balloon, the crimping including the steps of; reducing the scaffold diameter from the pre-crimp diameter to an intermediate diameter, pressurizing the balloon while the scaffold diameter is equal to, or less than the intermediate diameter, reducing the scaffold diameter from the intermediate diameter to a final diameter, and after the scaffold has attained the final diameter, placing the scaffold and balloon within a restraining sheath, wherein the balloon'"'"'s N pre-set folds are retained when the scaffold and balloon are within the restraining sheath. - View Dependent Claims (26, 27, 28, 29)
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Specification