title: Role of the "dogbone" effect of balloon-expandable stents: quantitative coronary analysis of DUET and NIR stent implantation introducing a novel indexing system.
abstract: Stent design and deployment characteristics of balloon-expandable stents may play an important role in determining both early and late outcomes of stenting. The purpose of this study was to compare the percent residual stenosis (RS) of two new-generation stent delivery systems, DUET and NIR, in patients with CAD. From September 1998 1999, a total of 100 consecutive patients with CAD receiving either a DUET (18 or 23 mm length; n = 50) or NIR stent (16 or 25 mm length; n = 50) using a 3.0 or 3.5 mm stent delivery system were compared by quantitative coronary analysis. The ability of each balloon delivery system to fully expand the stent was assessed using a new scoring index entitled the stent delivery balloon expansion ratio (SDBR; %). A high SDBR correlates with the angiographic appearance of a "dogbone" that is sometimes seen during stent deployment. A stent "scalloping" score was developed to quantitatively assess the cobblestone appearance observed angiographically with plaque protrusion after stent implantation. Mean deployment pressures were 14 +/- 2 atm (DUET) and 13 +/- 2 atm (NIR) (p=NS). Extent of elastic recoil was similar (6 +/- 5% for DUET vs. 6 +/- 4% for NIR; (p=NS). "Scalloping" was more pronounced in the DUET stent (score, 0.66 +/- 0.6 for DUET vs. 0.24 +/- 0.4 for NIR; p < 0.001). SDBR and RS were higher with DUET than with NIR stent implantation (SDBR, 15 +/- 5% vs. 12 +/- 5%; RS, 14 +/- 5% vs. 11 +/- 6%; p < 0.01). Multivariate analysis showed that SDBR and stent recoil, but not "scalloping", were associated with increased RS after stent implantation (r = 0.45 and p < 0.001 for "dogbone" effect; r = 0.39 and p < 0.001 for stent recoil).
  
  
  CONCLUSIONS
  The second-generation DUET and NIR stents and their respective delivery systems show angiographically different acute performance characteristics. Insufficient deployment of stents visualized by the "dogbone" effect plays a role in the extent of RS after stenting. The introduced angiographic indexes require further validation.
authors.affiliation: Department of Cardiology, University of Freiburg, Hugstetterstr. 55, 79106, Freiburg, Germany. hehrlein@medl.ukl.uni-freiburg.de
authors.forename: Christoph
authors.initials: C
authors.lastname: Hehrlein
authors.forename: Jennifer J
authors.initials: JJ
authors.lastname: DeVries
authors.forename: Amina
authors.initials: A
authors.lastname: Arab
authors.forename: Scott D
authors.initials: SD
authors.lastname: Haller
authors.forename: Ann
authors.initials: A
authors.lastname: Kloostra
authors.forename: Michael A
authors.initials: MA
authors.lastname: Lauer
authors.forename: Malcom T
authors.initials: MT
authors.lastname: Foster
authors.forename: Tim A
authors.initials: TA
authors.lastname: Fischell
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D019917:Blood Vessel Prosthesis Implantation / Q000295:instrumentation / Q000379:methods; D002404:Catheterization / Q000295:instrumentation*; D017023:Coronary Angiography; D003324:Coronary Artery Disease / Q000150:complications / Q000000981:diagnostic imaging / Q000628:therapy; D023903:Coronary Restenosis / Q000000981:diagnostic imaging / Q000209:etiology; D004867:Equipment Design / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012720:Severity of Illness Index; D015607:Stents; D016896:Treatment Outcome