Won-Pil Park

Suggestion of Potential Stent Design Parameters to Reduce Restenosis Risk driven by Foreshortening or Dogboning due to Non-uniform Balloon-Stent Expansion

The foreshortening or dogboning of a stent that occurs due to transient non-uniform balloon-stent expansion can induce a vascular injury, resulting in restenosis of the coronary artery. However, previous studies rarely considered the effects of transient non-uniform balloon expansion on analysis of the mechanical properties and behaviors of stents during stent deployment, nor did they determine design parameters to minimize the restenosis risk driven by foreshortening or dogboning. The aim of the current study was, therefore, to suggest potential design parameters capable of reducing the possibility of restenosis risk driven by foreshortening or dogboning through a comparative study of seven commercial stents using finite element (FE) analyses of a realistic transient non-uniform balloon-stent expansion process. The results indicate that using stents composed of opened unit cells connected by bend-shaped link structures, in particular the MAC Plus stent, and controlling the geometrical and morphological features of the unit cell strut or the link structure at the distal ends of stent may prevent restenosis risk caused by foreshortening or dogboning. This study provides a first look at the realistic transient non-uniform balloon-stent expansion by investigating the mechanical properties, behaviors, and design parameters capable of reducing the possibility of restenosis risk induced by the foreshortening or the dogboning.

Comparative Studies of Different Vascular Stents in terms of Mechanical Performances: Finite Element Analysis

Seven representative commercialized stents were evaluated by FE analysis in terms of the criteria based on the itemized list of Food and Drug Administration (FDA) and European Standards (prEN). Tenax and MAC standard were generally excellent in various evaluation items. Palmaz-Schatz was the most excellent in fatigue durability, but its flexibility was a little inferior than that of other stents. This study may suggest a guideline for improvement in stent design and function.

DEVELOPMENT AND CLINICAL TESTING OF AN ULTRASONIC DIAGNOSTIC SYSTEM FOR FUNCTIONAL GASTROINTESTINAL DISORDERS

Functional gastrointestinal disorders (FGIDs) affect millions of people without regard for age, race or sex, but little information related to FGIDs and few methods are available for diagnosing FGIDs. Therefore, the aims of this study were to investigate any alterations to the gastrointestinal tracts induced by FGIDs and to develop and test an ultrasonic diagnostic system capable of detecting the alteration in the gastrointestinal tract. Palpation/percussion examinations were performed on 40 participants with or without FGIDs to identify any mechanical alterations to the gastrointestinal tract induced by FGIDs. An ultrasonic diagnostic system for FGIDs was developed and clinical trials were performed on same participants used in the palpation/percussion examinations to test the system under actual clinical conditions. The results obtained from the palpation/percussion examinations showed that a gastrointestinal tract with a FGID became more rigid than a healthy tract (p < 0.05). Clinical trials also showed that gastrointestinal tracts in the patient group with FGIDs were in fact more rigid than those in the control group without FGIDs (p < 0.05). These findings indicated that our newly designed ultrasonic diagnostic system may be useful in clinics to accurately diagnose FGIDs through detecting mechanical alterations to the rigidity of the gastrointestinal tract induced by FGIDs. The current study may be valuable by identifying for the first time mechanical alterations of the gastrointestinal tract induced by FGIDs and may prove valuable as the first step in the development of a diagnostic system for FGIDs.

Relationship Between Obesity and Osteopenia in Lumbar Spines of Rats Using Mechanical and Morphological Studies

Obesity (OB) and osteopenia (OP), grave consequences for human health, quality of life, and even the efficiency of the labor force and economy, are two common complex diseases. Two public health problems have exploded in prevalence over the past decade [1]. OB, now a major epidemic in the developed world and frequent among elderly subjects, is a condition of excessive body fat that causes or exacerbates several risk of developing non-insulin dependent diabetes mellitus, cardiovascular disease, cancer and other diseases [2]. OP is defined as a systemic skeletal disease caused by low bone mass and microstructural deterioration of the bone.© 2008 ASME