Late Stent Expansion and Neointimal Proliferation of Oversized Nitinol Stents in Peripheral Arteries

For peripheral endovascular intervention, self-expanding (SE) stents are commonly oversized in relation to target arteries to assure optimal wall apposition and prevent migration. However, the consequences of oversizing have not been well studied. The purpose of this study was to examine the effects...

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Bibliographic Details
Published in:Cardiovascular and interventional radiology 2009-07, Vol.32 (4), p.720-726
Main Authors: Zhao, Hugh Q., Nikanorov, Alexander, Virmani, Renu, Jones, Russell, Pacheco, Erica, Schwartz, Lewis B.
Format: Article
Language:English
Subjects:
ALLOYS
ANESTHETICS
ANIMALS
ANTICONVULSANTS
ARTERIES
AZINES
BARBITURATES
BIOMEDICAL RADIOGRAPHY
BLOOD VESSELS
BODY
Cardiology
CARDIOVASCULAR SYSTEM
CENTRAL NERVOUS SYSTEM AGENTS
CENTRAL NERVOUS SYSTEM DEPRESSANTS
DIAGNOSTIC TECHNIQUES
DOMESTIC ANIMALS
DRUGS
EXPANSION
Fluoroscopy
HETEROCYCLIC COMPOUNDS
HYPNOTICS AND SEDATIVES
Imaging
Laboratory Investigation
Linear Models
MAMMALS
MEDICINE
Medicine & Public Health
NICKEL ALLOYS
NUCLEAR MEDICINE
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
ORGANS
Peripheral Vascular Diseases - etiology
Peripheral Vascular Diseases - pathology
PHENOBARBITAL
PROLIFERATION
Prosthesis Design
Prosthesis Fitting
PYRIMIDINES
RADIOLOGY
RADIOLOGY AND NUCLEAR MEDICINE
Stents - adverse effects
SWINE
TITANIUM ALLOYS
TRANSITION ELEMENT ALLOYS
TUBES
Tunica Intima - pathology
Ultrasound
Vascular Patency
VERTEBRATES
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Summary:For peripheral endovascular intervention, self-expanding (SE) stents are commonly oversized in relation to target arteries to assure optimal wall apposition and prevent migration. However, the consequences of oversizing have not been well studied. The purpose of this study was to examine the effects of SE stent oversizing (OS) with respect to the kinetics of late stent expansion and the long-term histological effects of OS. Pairs of overlapped 8 × 28-mm Nitinol SE stents were implanted into the iliofemoral arteries of 14 Yucatan swine. Due to variations in target artery size, the stent-to-artery ratio ranged from 1.2:1 to 1.9:1. Lumen and stent diameters were assessed by quantitative angiography at the time of implantation. Following angiographic assessment at 6 months, stented arteries were perfusion-fixed, sectioned, and stained for histological analysis. Immediately following implantation, the stents were found to be expanded to a range of 4.7–7.1 mm, largely conforming to the diameter of the recipient target artery. The stents continued to expand over time, however, and all stents had enlarged to nearly their 8-mm nominal diameter by 6 months. The histological effects of OS were profound, with marked increases in injury and luminal area stenosis, including a statistically significant linear correlation between stent-to-artery ratio and area stenosis. In this experimental model of peripheral endovascular intervention, oversized Nitinol SE stents are constrained by their target artery diameter upon implantation but expand to their nominal diameter within 6 months. Severe OS (stent-to-artery ratio >1.4:1) results in a profound long-term histological response including exuberant neointimal proliferation and luminal stenosis.
ISSN:0174-1551
1432-086X
DOI:10.1007/s00270-009-9601-z