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Publication Number
US-9937068-B2
Publication Date
2018-04-10
Expiration Date
Abstract
The present patent application relates to a method of crimping a tubular stent having a stent lumen onto an inflatable balloon of a stent delivery catheter.
Core Innovation
The invention relates to a method of crimping a bioresorbable polymeric tubular stent having a stent lumen onto an inflatable balloon of a stent delivery catheter. The tubular stent has deployed diameter and a crimped diameter smaller than the deployed diameter, with stent struts evenly distributed around the stent lumen and interstices between the stent struts. The inflatable balloon has a wall material arranged into folds and evenly distributed around the stent lumen.
The method inserts the inflatable balloon of the stent delivery catheter into the stent lumen of the tubular stent with the inflatable balloon at a deflated diameter while the tubular stent is approximately at the deployed diameter. The tubular stent is heated to a temperature at or above the glass transition temperature (Tg) of the bioresorbable polymer, and the inflatable balloon is inflated to an inflation pressure between 0.1 to 5 bars within the stent lumen while the tubular stent is crimped from the deployed diameter to the crimped diameter.
After crimping, the tubular stent is cooled to a temperature below the glass transition temperature while maintaining the inflation pressure within the inflatable balloon. The inflatable balloon is then deflated while maintaining the tubular stent at the crimped diameter, to retain the crimped diameter configuration. The disclosed crimping approach is positioned against prior art metal-stent crimping and polymer crimping that inflates the balloon differently, including a contrast directed to retention and homogeneity of crimping and deployment and distribution.
Claims Coverage
The document includes one independent method claim, describing an ordered sequence with heating to at or above Tg, controlled inflation during crimping, cooling below Tg, and deflating while maintaining the stent at the crimped diameter; dependent claims further refine material selection, pressure conditions, precrimping, and removal steps.
Crimping sequence using Tg heating, low-pressure balloon maintenance, cooling below Tg, and deflation at retained crimped diameter
A method comprising, in order, inserting the deflated inflatable balloon into the stent lumen with the tubular stent at approximately the deployed diameter; heating the tubular stent to a temperature at or above the glass transition temperature (Tg); inflating the inflatable balloon to an inflation pressure between 0.1 to 5 bars and crimping from the deployed diameter to the crimped diameter while maintaining the inflation pressure; cooling the tubular stent to a temperature below Tg while maintaining the inflation pressure; and deflating the inflatable balloon while maintaining the tubular stent at the crimped diameter.
Precrimping with a crimping machine to form a precrimped diameter relation to the deployed diameter
The method further includes precrimping the tubular stent before inserting the inflatable balloon, by placing the tubular stent in a crimping machine at about the deployed diameter to form a precrimped diameter slightly smaller than the deployed diameter.
Post-crimp pressure increase before deflating while maintaining the stent at crimped diameter
The method further increases the inflation pressure of the inflatable balloon to approximately 3.0 to 7.0 bars after crimping and before deflating, while keeping the tubular stent at its crimped diameter.
Quantified balloon inflation and integrated precrimping, cooling, and deflating workflow with removal
The method includes precrimping at the deployed diameter after heating to at least the glass transition temperature, maintaining balloon inflation at about 0.2 to 2.0 bars during crimping, then increasing balloon inflation to about 3.0 to 7.0 bars, cooling below the glass transition temperature, and removing the tubular stent and inflatable balloon from the crimping machine after deflation.
Specific bioresorbable polymer material as poly(lactic acid)
The method further uses a tubular stent made from a poly(lactic acid) (PLA) polymer.
Post-deflation removal of stent and inflatable balloon from the crimping machine
After a deflating step, removing the tubular stent and the inflatable balloon of the stent delivery catheter from the crimping machine.
Claim coverage centers on an ordered crimping method for a bioresorbable polymeric tubular vascular stent using Tg-based heating and cooling and controlled balloon inflation to retain a crimped diameter, with dependent claims refining PLA material, precrimping via a crimping machine, specified inflation-pressure ranges during and after crimping, and removal of the stent and balloon from the crimping machine.
Stated Advantages
Improved retention.
More homogeneous crimping and deployment.
Improved expansion and tracking.
Reduced risk of uneven drug distribution.
Documented Applications
No documented applications found
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