Implantable medical device having reduced chance of late inflammatory response

• US 9,216,238 B2
• Filed: 04/14/2014
• Issued: 12/22/2015
• Est. Priority Date: 04/28/2006
• Status: Active Grant

• Current Assignee: Abbott Cardiovascular Systems Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Abbott Cardiovascular Systems Incorporated (Abbott Laboratories Incorporated)
• Inventors: Huang, Bin, Gale, David C.
• Primary Examiner(s): Arnold, Ernst V
• Application Number:
  US14/252,700
• Publication Number:
  US 20140228938A1
• Time in Patent Office: 617 Days
• US Class Current: 1/1
• CPC Class Codes: A61F 2/915 with bands having a meander structure, adjacent bands being connected to each other
• CPC Class Codes: A61L 31/06 obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds A61L31/041 takes precedence
• CPC Class Codes: A61L 31/148 Materials at least partially resorbable by the body
• CPC Class Codes: B23K 2103/42 Plastics B23K2103/16 takes precedence
• CPC Class Codes: B23K 2103/50 Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26
• CPC Class Codes: B23K 26/402 involving non-metallic material, e.g. isolators
• CPC Class Codes: B29B 13/02 by heating B29B13/06, B29B13/08 take precedence
• CPC Class Codes: B29C 71/0063 for changing crystallisation
• CPC Class Codes: B29L 2031/7532 Artificial members, protheses
• CPC Class Codes: C08L 67/04 Polyesters derived from hydroxycarboxylic acids, e.g. lactones C08L67/06 takes precedence

Abstract

The invention provides a method for fabricating an implantable medical device to increase biocompatibility of the device, the method comprising: heat setting a polymer construct, wherein the polymer construct is at a temperature range of from about Tg to about 0.6(Tm−Tg)+Tg such that the set polymer construct comprises a crystalline structure having crystals at a size less than about 2 microns; and fabricating an implantable medical device from the heat set polymer construct.

Claims

1. A biodegradable stent comprising:

a cylindrically-shaped scaffold comprising a biodegradable polymer including a poly(L-lactide) based polymer,

wherein the scaffold includes a pattern comprising a network of interconnected struts, the pattern formed by cutting a tube including the poly(L-lactide) based polymer,

wherein a crystallinity of the tube is increased by processing, the processing comprising heating and radially expanding the tube prior to forming the pattern,

wherein the scaffold has induced molecular orientation in the circumferential direction due to the radially expanding,

wherein the biodegradable polymer after the processing has a crystallinity between 5% and 60% and comprises crystals dispersed in an amorphous domain, the crystals having a size less than 10 microns, and

wherein the scaffold is radially expandable and has adequate radial strength from the increased crystallinity and induced circumferential orientation to hold open a blood vessel in a body when the scaffold is radially expanded in a blood vessel.

2. The stent of claim 1, wherein the biodegradable polymer after the processing has a crystallinity between 45% and 55%.

3. The stent of claim 1, wherein the crystals have a size less than 6 microns.

4. The stent of claim 1, wherein a majority of the crystals are of a crystal size less than 2 microns.

5. A method of treating atherosclerotic stenosis in a blood vessel with a biodegradable stent comprising:

identifying a patient in need of treatment of atherosclerotic stenosis having an atherosclerotic segment in a blood vessel; and

expanding the segment with a biodegradable stent including a cylindrically-shaped scaffold comprising a biodegradable polymer including a poly(L-lactide) based polymer,

wherein the scaffold includes a pattern comprising a network of interconnected struts, the pattern formed by cutting a tube including the poly(L-lactide) based polymer,

wherein the biodegradable polymer of the scaffold has a crystallinity between 5% and 60% and comprises crystals that are less than 2 microns dispersed in an amorphous domain,

wherein when the amorphous domain is preferentially eroded compared to the crystals, the crystals that are left behind of less than 2 microns are small enough to be digested by macrophages which reduces a late inflammatory reaction, and

wherein the scaffold has adequate radial strength from the crystallinity to hold open the blood vessel.

6. The method of claim 5, wherein the biodegradable polymer of the scaffold has a crystallinity between 45% and 55%.

7. The method of claim 5, wherein a majority of the crystals are of a crystal size less than 2 microns.