• 대한핵의학회:학술대회논문집
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• 1999.05a
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• pp.205-208
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• 1999

Percutaneous Transluminal Coronary Angioplasty (PTCA) remains limited by restenosis that occurs in 30 to 50% of patients with coronary artery disease. During the last decade, numerous agents have been used to prevent restenosis. Despite positive results in animal models, no pharmacological therapy has been found to significantly decrease the risk of restenosis in humans. These discrepancies between animal models and clinical situation were probably related to an incomplete understanding of the mechanism of restenosis. Neointimal thickening occurs in response to experimental arterial injury with a balloon catheter. Neointimal formation involves different steps: smooth muscle cell activation, proliferation and migration, and the production of extracellular matrix. The factors that control neointimal hyperplasia include growth factors, humoral factors and mechanical factors. Arterial remodeling also plays a major role in the restenosis process. Studies performed in animal and human subjects have established the potentials for "constrictive remodeling" to reduce the post-angioplasty vessel area, thereby indirectly narrowing the vessel lumen and thus contributing to restenosis. The reduction of restenosis rate in patients with intracoronary stent implantation has been attributed to the preventive effect of stent itself for this negative remodeling. In addition to these mochanisms for restenosis, intraluminal or intra-plaque thrombus formation, reendothelialization and apoptosis theories have been introduced and confirmed at least in part.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.1 s.256
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• pp.21-28
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• 2007

The use of drug-eluting stents has dramatically reduced the incidence of restenosis however, much remains to be teamed about the performance of these stouts. In the present study, we tested the hypothesis that the design of drug-eluting stents influences the efficacy of local drug delivery to the arterial wall and that this effect depends on both arterial geometry and the prevailing flow conditions. We performed computational simulations in which the coupled Navier-Stokes and advection-diffusion equations were solved to determine the flow field and drug concentration in the vicinity of model drug-eluting stouts It is found that the characteristics of flow phenomena can be influenced greatly by the ratio of stent diameter to vessel diameter. The presence of drug-eluting stent may have profound effect on wall shear stresses, recirculation sizes and drug distributions. The results show that recirculation zone is influenced by the imposed flow conditions and stent diameter. In pulsatile flow, the low wall shear stress and high drug concentration occur along the arterial wall during the decelerating flow conditions. These results could provide the guideline for future drug-eluting stent designs toward reducing restenosis by affecting local wall shear stress distributions associated with neointimal hyperplasia.

• Journal of Society of Preventive Korean Medicine
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• v.12 no.3
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• pp.67-80
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• 2008

The pathobiologic process of arterial stenosis following balloon angioplasty continues to be an enigmatic problem in clinical settings. This study investigates the ability of demethoxycurcumin, a curcuminoid isolated from Radix Curcumae, to attenuate balloon injury-induced neointima(NI) formation in the rat carotid artery. It was found that demethoxycurcumin induced inducible heme oxygenase(HO-1) expression and inhibited dose-dependently cellular proliferation in rat vascular smooth muscle cells. Perivascular application of demethoxycurcumin immediately following injury significantly reduced NI area and NI thickness 2 weeks post-injury. Interestingly, treatment with tin-protoporphyrin IX, a HO inhibitor, reversed the effects of demethoxycurcumin on NI formation. These results implicate demethoxycurcumin as a potent new therapeutic agent that is capable of reducing post-angioplasty arterial stenosis through induction of the HO-1 expression.

• Nuclear Medicine and Molecular Imaging
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• v.40 no.2
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• pp.106-112
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• 2006

Tissue hyperplasia is one of the most frequently encountered complications when self-expanding metallic stents are placed in benign non-vascular luminal organ strictures, thus causing restenosis of the lumen. The investigators postulated that ionizing irradiation could be applied to prevent restenosis caused by tissue hyperplasia in non-vascular luminal organs as it reduced coronary or peripheral arterial narrowing successfully. The authors combined $\beta$-irradiation using $^{188}Re-MAG_3$ solution with balloon dilation for animal and clinical studies because this new treatment approach had the advantages such as low penetration depth of $\beta$-ray, self-centering irradiation, and mechanical effect of balloon dilation over using $\gamma$-irradiation with afterloading devices in this article, the concept and mechanism of radioisotope balloon dilation, and animal and clinical studies using radioisotope balloon dilation are reviewed.

• Journal of Korean Neurosurgical Society
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• v.65 no.2
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• pp.180-185
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• 2022

Objective : Drug-eluting stents and balloons are occasionally used to reduce restenosis in medically intractable intracranial atherosclerotic stenosis. The authors aimed to determine whether such drugs can cause neurotoxicity due to local effects in a rat model. Methods : Intra-arterial catheters were placed in the right common carotid artery of rats. Mannitol was injected to transiently open the brain-blood barrier (BBB), followed by high-dose drug (paclitaxel and rapamycin) injection. The optimal time interval of transient BBB opening for maximal drug penetration was determined to be 10 minutes. Paclitaxel and rapamycin were intra-arterially administered in various doses. All the rats were neurologically evaluated, and their brain tissues were histologically examined. Results : Neither neurological deficits nor histological abnormalities were observed in all the rats. Conclusion : Paclitaxel and rapamycin did not cause neurotoxicity in a rat model with transient BBB opening.

• Applied Chemistry for Engineering
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• v.31 no.5
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• pp.502-508
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• 2020

Dual drug-eluting stents (DES) is a primary treatment method for coronary arterial diseases in current interventional cardiology practice. However, their pathological results according to the sequence of coating of drugs have not been reported yet. The peptide-dopamine dissolved in acetonitrile was coated onto the Chonnam National University Hospital (CNUH) stent using an electrospinning coating machine. For secondary coating (e.g., sirolimus coating, designated as SPS), sirolimus (SRL) and poly lactic-glycolic acid (PLGA) were mixed in tetrahydrofuran (THF), and the solution was then coated on the CNUH stent that had underwent the primary peptide coating using an electrospinning and spray technique. Next, the peptide-dopamine was coated on the SRL-PLGA coated stent (PSS). In this study, it was confirmed that endothelialization was promoted without being significantly affected by the coating order (SPS or PSS). The sequence of drug and peptide coating may affect the development of restenosis and PSS was effective in the prevention of restenosis compared to that of using SPS.

• Journal of Korean Neurosurgical Society
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• v.49 no.6
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• pp.370-372
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• 2011

Dissection of the middle cerebral artery (MCA) is less frequent compared with dissection of the vertebrobasilar system or carotid artery. Recently, high-resolution cross sectional MR imaging (HRMRI) has emerged as a potential technique for atherosclerotic plaque imaging in MCA, We introduce the findings of HRMRI in a 56-year-old woman with traumatic MCA dissection, HRMRI showed an intimal flap and tapered pseudolumen with intra-luminal hemorrhage, We performed stent deployment about MCA dissection after failed medical treatment Three months later, there was no in-stent restenosis and no further neurological deficit were noted.

• Korea-Australia Rheology Journal
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• v.21 no.4
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• pp.281-288
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• 2009

Numerical investigations have been conducted on the assessment of the performance of drug-eluting stent. Computational fluid dynamics is applied to investigate the flow disturbances and drug distributions released from the stent in the immediate vicinity of the given idealized stent in the protrusion into the flow domain. Our simulations have revealed the drug concentration in the flow field due to the presence of a drug-eluting stent within an arterial segment. Wall shear stress increases with Reynolds number for a given stent diameter, while it increases with stent diameter for a given Reynolds number. The drug concentration is dependent on both Reynolds number and stent geometry. In pulsatile flow, the minimum drug concentration in the zone of inter-wire spacing occurs at the maximum acceleration of the inlet flow while the maximum drug concentration gains at the maximum deceleration of the inlet flow. These results provide an understanding of the flow physics in the vicinity of drug-eluting stents and suggest strategies for optimal performance of drug-eluting stent to minimize flow disturbance.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1919-1922
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• 2003

Bypass anastomosis are frequently adopted for surgical treatments. After the bypass grafting, the bypass artery is often occluded due to restenosis and/or anastomotic neointimal fibrous hyperplasia phenomena. Optimal coronary bypass anastomosis should be investigated to improve the patency for the arterial bypass techniques. The objective of this study is to investigate the influence of bypass with sequential bypass effects in the stenosed coronary artery. Numerical analyses are focused on the understanding of the flow patterns for different sequential anastomosis techniques. Blood flow field is treated as two-dimensional incompressible laminar flow. The finite volume method is adopted for discretization of the governing equations. The Carreau model is employed as the constitutive equation for blood. To find the optimal sequential bypass anastomotic configurations, the mass flow rates at the outlet of different models are compared quantitatively.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1915-1918
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• 2003

Atherosclerosis, which is a degenerate disease, is believed to occur in the vascular system due to deposition of cholesterol and low density lipoprotein(LDL) or thrombosis on the blood vessel. Atherosclerosis narrows arterial lumen, which is known as stenosis phenomenon of blood vessel. Pathogenesis of atherosclerosis is thought to occur mainly by aging. Restenosis phenomenon is observed in the same site of insertion of a stent and balloon angioplasty after treatment of interventional theraphy. Several hypothetical theories related to the generation of atherosclerosis have been reported: high shear stress theory, low shear stress theory, high shear stress gradient theory, flow separation and turbulence theory and high pressure theory. However, no one theory clearly explains the causes of atherosclerosis. In the present study the generation of atherosclerosis in the left coronary artery is investigated. The hypotheses are verified by using the computer simulation.