• Journal of Korean Neurosurgical Society
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• 제56권4호
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• pp.344-347
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• 2014

Stent thrombosis is a major limitation of stent-assisted coiling, which is an effective method for treating wide-necked aneurysms. Although early in-stent thrombosis has been reported, very late stent thrombosis (VLST) (>1 year) has not been reported following implantation of a single self-expandable stent designed for coiling. Herein, the authors present a case of VLST that occurred 14 months after single stent implantation in a large paraclinoid aneurysm with an ultra-wide neck involving the parent artery circumferentially. This case indicates the need for establishing guidelines regarding the optimal duration of prophylactic antiplatelet therapy following stent-assisted coiling, which remains undefined in the neuroendovascular field.

• Journal of Korean Neurosurgical Society
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• 제48권6호
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• pp.485-489
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• 2010

Objective : To introduce the frequency and segment analysis of in-stent stenosis for intracranial stent assisted endovascular treatment on complex aneurysms. Methods : A retrospective study was performed in 158 patients who had intracranial complex aneurysms and were treated by endovascular stent application with or without coil embolization. Of these, 102 patients were evaluated with catheter based angiography after 6, 12, and 18 months. Aneurysm location, using stent, time to stenosis, stenosis rate and narrowing segment were analyzed. Results : Among follow-up cerebral angiography done in 102 patients, 8 patients (7.8%) were shown an in-stent stenosis. Two patients have unruptured aneurysm and six patients have ruptured one. Number of Neuroform stents were 7 cases (7.5%) and Enterprise stent in 1 case (11.1%). Six patients demonstrated in-stent stenosis at 6 months after stent application and remaining two patients were shown at 12 months, 18 months, respectively. Conclusion : In-stent stenosis can be confronted after intracranial stent deployment. In our study, no patient showed symptomatic stenosis and there were no patients who required to further treatment except continuing antiplatets medication. In-stent stenosis has been known to be very few when they are placed into the non-pathologic parent artery during the complex aneurysm treatment, but the authors found that it was apt to happen on follow up angiography. Although the related symptom was not seen in our cases, the luminal narrowing at the stented area may result the untoward hemodynamic event in the specific condition.

• 한국임상수의학회지
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• 제27권4호
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• pp.457-461
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• 2010

Three dogs were presented with signs of recurrence of coughing, dyspnea and difficulty of barking after endotracheal stent placement. On the basis of history taking, physical examination, laboratory tests and radiography, complications of endotracheal stent were suspected. Dog 1 had unfitted stent diameter (stent diameter is larger than tracheal diameter) and getting disentangled of proximal tracheal stent wire. Dog 2 was suspected a foreign body reaction. Dog 3 had the migration of stent caudally. Based on these cases, the veterinarian should accurately evaluate the indicated patients before endotracheal stent and has to select the appropriate stent (diameter, length and location) to prevent complications after endotracheal stent and concern the regular follow-ups to assure proper endotracheal stent placement.

• Korea-Australia Rheology Journal
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• 제21권4호
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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.

• 대한기계학회논문집B
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• 제29권9호
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• pp.1042-1048
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• 2005

Numerical investigation has been made on the stent design to minimize the neointimal hyperplasia. Computational fluid dynamics is applied to investigate the flow distributions in the immediate vicinity of the given idealized stent implanted in the blood vessel. Parametric study on the variations of the number of stouts, stent diameters, stent spacings and Reynolds numbers has been conducted using axi-symmetric Navier-Stokes equations. An initial difficulty in the study is to determine the optimal stent design to understand the flow physics of the flow disturbance induced by stent. The size of recirculation zone around stent is depend on the stent diameter, number of stent wire and Reynolds number but is insensitive to the stent wire spacing. It is also found that when the flow is in acceleration, the flow sees a more favorable pressure gradient, and the separation zones are smaller than the steady flow case. When the flow is in deceleration and the flow sees a more adverse pressure gradient so that the separation zones are larger.

• 대한기계학회논문집B
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• 제35권10호
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• pp.1053-1060
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• 2011

본 연구는 이상적인 원형 환(Ideal Circular Ring) 스텐트와 Intertwined 스텐트의 삽입에 의해 야기 되는 혈류유동 형태와 스텐트 표면에서 방출되는 약물의 농도분포를 조사하는 것이다. 본 연구를 통해 Intertwined 스텐트의 스텐트 사이 영역에서 약물농도는 원형 환 스텐트에 비해 더 많이 분포해 있는 것을 알 수 있었다. 주어진 스텐트의 형상에 대하여 스텐트 사이 영역에서의 국소적인 약물 농도분포는 레이놀즈 수가 증가함에 따라 감소하는 것으로 나타났다. 주어진 레이놀즈 수에 대하여는 약물 농도분포는 스텐트의 형상과는 비교적 무관함을 알 수 있다. 원형 환 스텐트보다 Intertwined스텐트가 스텐트사이 영역과 스텐트 하류영역에서혈관 벽면을 따른 약물 농도분포는 크게 나타나는 것을 볼 수 있다.

• 한국임상수의학회지
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• 제37권3호
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• pp.115-122
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• 2020

The aim of this study was to evaluate double-pigtail ureteral stent fixation in cats. Medical records of 19 cats (23 ureters) with complete ureteral obstruction that double-pigtail ureteral stent placement were carried out were retrospectively reviewed. The cats were randomly classified into two groups; 13 cats (16 ureters) with double-pigtail ureteral stent fixed to urinary bladder (SF group) and 6 cats (7 ureters) with not fixed to urinary bladder (SNF group). The average age and weight of the cats was 7.4 years and 3.73 kg, respectively. Postoperative complications included chronic renal failure (n = 11), lower urinary track diseases (cystitis, hematuria, pollakiuria) (n = 7), stent migration (n = 6), anemia (n = 5), ascites (n = 2), hyperthermia (n = 1), enteritis (n = 1), oliguria (n = 1), hypotension (n = 1), ureteritis (n = 1), and pyelonephritis (n = 1). Stent migration did not occur in the 16 ureters of the cats in SF group but did occur in 4 out of 7 ureters of the cats in SNF group. The prevention of stent migration by stent fixation was significant (P = 0.04). Among the 13 cats in SF group, only 2 cats developed lower urinary track diseases, while 4 of the 6 cats in SNF group showed symptoms of lower urinary track disease. Thus, the cats that underwent double-pigtail ureteral stent fixation to the urinary bladder developed significantly fewer lower urinary diseases (P = 0.046). In conclusion, double-pigtail ureteral stent fixation to the urinary bladder for treatment of complete ureteral obstruction in cats can effectively prevent stent migration, which is common complication of stent placement.

• 한국정밀공학회지
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• 제23권10호
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• pp.121-125
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• 2006

In this paper, results are presented by nonlinear finite element simulations in order to analy the interactions between the stent and artery or plaque. Maximum of von Mises stress was calculated in the contacting areas between the stent and the artery. The simulated results show that the distal end of stent, which tilts after expansion, may injure the artery wall. In conclusion, this study may help designing new stents.

• Journal of Korean Neurosurgical Society
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• 제51권4호
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• pp.222-226
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• 2012

The waffle-cone technique is a modified stent application technique, which involves protrusion of the distal portion of a stent into an aneurysm fundus to provide neck support for subsequent coiling. The authors report two cases of wide necked basilar bifurcation aneurysms, which were not amenable to stent assisted coiling, that were treated using the waffle-cone technique with a Solitaire AB stent. A 58-year-old woman presented with severe headache. Brain CT showed subarachnoid hemorrhage and angiography demonstrated a ruptured giant basilar bifurcation aneurysm with broad neck, which was treated with a Solitaire AB stent and coils using the waffle-cone technique. The second case involved an 81-year-old man, who presented with dizziness caused by brain stem infarction. Angiography also demonstrated a large basilar bifurcation unruptured aneurysm with broad neck. Solitaire AB stent deployment using the waffle-cone technique, followed by coiling resulted in near complete obliteration of aneurysm. The waffle-cone technique with a Solitaire AB stent can be a useful alternative to conventional stent application when it is difficult to catheterize bilateral posterior cerebral arteries in patients with a wide-necked basilar bifurcation aneurysm.

• Journal of Korean Neurosurgical Society
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• 제51권6호
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• pp.370-373
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• 2012

The intracranial stent functions primarily to prevent protrusion of coils into the parent vessel during the embolization of wide-necked cerebral aneurysms and might also reduce aneurysm recanalization rate. In spite of these advantages, little is known about the long-term interaction of the stent with the parent vessel wall. We present a rare case of severe in-stent stenosis occurring as a delayed complication of Neuroform stent-assisted coil embolization of an unruptured intracranial aneurysm.