• Journal of the Korea Computer Graphics Society
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• v.17 no.2
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• pp.11-16
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• 2011

In computer graphics, shadows play a very important role as a hint of inter-object distance as well as themselves in terms of realism. To represent shadows, some traditional methods such as shadow mapping and shadow volume have been frequently used for the purpose. However, the rendering results are not natural since they assume the point light. On the contrary, an area light can render soft-shadows, but its computation is too burdensome due to integral over the whole light source surface. Many alternatives have been introduced, back-projection of occluder onto the light source to get visibility of light or filtering of shadow boundary by calculating size of penumbra. But they also have problems of light bleeding or ringing effects because of low order approximation, or low performance. In this paper, we describe a method to improve those problems using shadow atlas.

• Clinical and Experimental Pediatrics
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• v.48 no.10
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• pp.1143-1143
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• 2005

The traumatic ventricular septal defect (VSD) is a rare but potentially life threatening complication of chest wall injury. The traumatic VSD occurs in up to 4.5% of penetrating cardiac trauma. Most of the patients are usually operated on because of heart failure and/or significant left-to-right shunt. The feasibility of surgical repair under cardiopulmonary bypass may be affected by coexisting pulmonary, cerebral or other vascular injuries. Transcatheter closure of VSD is being considered as an alternative therapeutic modality to surgery in order to avoid the potential risk of cardiopulmonary bypass. We report a patient who underwent a successful transcatheter closure of VSD with an $Amplatzer^{(R)}$ VSD occluder. The patient had a residual VSD with significant left-to-right shunt after surgical repair of post-traumatic VSD using cardiopulmonary bypass.

• Journal of Chest Surgery
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• v.39 no.2 s.259
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• pp.150-153
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• 2006

Percutaneous transcatheter closure of atrial septal defects as a therapeutic alternative in appropriate patients provides superior cosmetic results, is less invasive, and allows for shorter hospital stays. Unfortunately, however, such percutaneous procedures can be associated with catastrophic procedure complications that may require immediate surgical intervention. We report a case of aorta-to-right atrial fistula two months after transcatheter occlusion of an atrial septal defect by an Amplatzer septal occluder. Revealed by dyspnea, palpitation and hemolysis, this complication needed an emergency surgical operation. The fistula between the noncoronary Valsalva sinus of the aorta and the right atrium was repaired. The atrial septal defect was closed by patch. The cause of this serious complication appears to be erosion into the aorta by the right atrial disk.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.25 no.2
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• pp.147-162
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• 2022

Purpose: To design a prospective study on endovascular closure of congenital portosystemic shunts. The primary endpoint was to assess the safety of endovascular closure. The secondary endpoint was to evaluate the clinical, analytical and imaging outcomes of treatment. Methods: Fifteen patients (age range: 2 days to 21 years; 10 male) were referred to our center due to congenital portosystemic shunts. The following data were collected prior to treatment: age, sex, medical history, clinical and analytical data, urine trimethylaminuria, abdominal-US, and body-CT. The following data were collected at the time of intervention: anatomical and hemodynamic characteristics of the shunts, device used, and closure success. The following data were collected at various post-intervention time points: during hospital stay (to confirm shunt closure and detect complications) and at one year after (for clinical, analytical, and imaging purposes). Results: The treatment was successful in 12 participants, migration of the device was observed in two, while acute splanchnic thrombosis was observed in one. Off-label devices were used in attempting to close the side-to-side shunts, and success was achieved using Amplatzer™ Ductus-Occluder and Amplatzer™ Muscular-Vascular-Septal-Defect-Occluder. The main changes were: increased prothrombin activity (p=0.043); decreased AST, ALT, GGT, and bilirubin (p=0.007, p=0.056, p=0.036, p=0.013); thrombocytopenia resolution (p=0.131); expansion of portal veins (p=0.005); normalization of Doppler portal flow (100%); regression of liver nodules (p=0.001); ammonia normalization (p=0.003); and disappearance of trimethylaminuria (p=0.285). Conclusion: Endovascular closure is effective. Our results support the indication of endovascular closure for side-to-side shunts and for cases of congenital absence of portal vein.

• Clinical and Experimental Pediatrics
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• v.51 no.4
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• pp.401-408
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• 2008

Purpose : Transcatheter closure of atrial septal defects (ASD) is currently established therapy as an alternative to surgery. But rarely, complications are reported in some studies. We report early and intermediate term complications associated with transcatheter closure of atrial septal defects using the Amplatzer septal occluder (ASO). Methods : From June 2003 to May 2006, 64 patients underwent transcatheter closure of secundum ASD or patent foramen ovale using the ASO. The ratio of male to female was 1:2.4, the median age was 17 years (range: 2.6-64 years) and their median weight was 47.5 kg (range: 2.6-64 kg). Results : The median diameter of ASD measured with transthoracic or transesophageal echocardiography was 15 mm (range: 6-28 mm), the median balloon stretched diameter was 18 mm (range: 6.5-34 mm), and the median size of device was 19.5 mm (range: 6-36 mm), was little difference with balloon stretched diameter. There were 10 cases of complications: arrhythmia (2), device malformation (2), aorta to right atrial fistula (1), hemolytic anemia (1), mitral valve encroachment (1), malposition (1), residual shunt (1), and inferior vena cava perforation (1). Conclusion : Transcatheter closure of ASD using ASO is effective and safe therapy. However, significant complications such as aorta to atrial fistula, atrial erosion, or device embolization can happen, so an appropriate selection of patient and device in relevance to size and anatomy of ASD is important for successful closure.

• Journal of Chest Surgery
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• v.50 no.2
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• pp.110-113
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• 2017

A 43-year-old man who had had a history of atrial septal defect (ASD) device closure 31 months previously presented with abrupt chest and back pain along with progressive cardiogenic shock and cardiac arrest. After resuscitation, he was diagnosed with cardiac tamponade. Diagnostic and therapeutic surgical exploration revealed left atrium (LA) perforation due to LA roof erosion from a deficient aortic rim. Device removal, primary repair of the LA perforation site, and ASD patch closure were performed successfully. The postoperative course was uneventful. The patient was discharged after 6 weeks of empirical antibiotic therapy without any other significant complications.

• Clinical and Experimental Pediatrics
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• v.52 no.4
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• pp.494-498
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• 2009

Purpose : Applicability of transcatheter closure of atrial septal defect (ASD) has been expanded by accumulation of clinical experiences and evolutions of the device. This study was performed to evaluate the safety and efficacy of transcatheter closure of ASD with Amplatzer septal occluder (ASO) in young children less than 3 years of age. Methods : From May 2003 to December 2005, 295 patients underwent transcatheter closure of ASD with ASO in the Severance Cardiovascular Hospital, Yonsei University Health System. Among them, 51 patients less than 3 years of age were enrolled in this study. We investigated procedural success rate, rate of residual shunt, frequency of complications, procedure/fluoroscopy time, and need of modified techniques for device implantation. Results : The median age was 2.1 years and median body weight was 12 kg. Implantation of device was successful in 50 patients (98%). Seven patients (15%) showed a small residual shunt 1 day after the procedure, but complete occlusion had been documented at 6 month follow-up in all patients (100%). The pulmonary to systemic flow ratio (Qp/Qs), peak systolic pulmonary artery pressure, and peak systolic right ventricular pressure had decreased significantly after closure of ASD. There were 2 complications including device embolization (1, 2%) and temporary groin hematoma (1, 2%). Conclusion : Transcatheter closure of ASD with ASO can be performed with satisfactory results and acceptable risk even in young children less than 3 years of age. We could suggest that even in very young children with ASD, there is no need to wait until they grow to a sufficient size for the transcatheter closure.

• Journal of the Korean Society of Radiology
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• v.82 no.2
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• pp.371-381
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• 2021

Purpose To evaluate the usefulness and effectiveness of bronchial occluders in the treatment of postoperative bronchopleural fistula (BPF). Materials and Methods The subjects of the study were six out of seven postoperative BPF patients who underwent surgery due to tuberculosis or lung cancer between 2009 and 2019. Each patient had a bronchial occluder inserted to treat BPF that occurred after surgery. Of the six patients, five had lung cancers and one had tuberculosis. Five were male and one was female; their ages ranged from 59 to 74 years, with an average of 69 years. The diagnosis of BPF was based on findings from bronchoscopy and CT, and treatment was initiated approximately 1 to 2 weeks after diagnosis. The technical and clinical success of the bronchial occluders in the treatment of BPF was evaluated. The study assessed the postoperative clinical effects of the occluders, survival duration, and additional treatments. Results All six patients were successfully treated. Clinical success was achieved in five patients, while partial clinical success was achieved in one; there was no clinical failure. No complications during the migration of the device or device perforations were observed. Two patients were diagnosed with BPF by CT, while four were diagnosed by bronchoscopy. Lobectomy, bilobectomy, and pneumonectomy were performed on two patients each. The periods between surgery and diagnosis ranged from 1 to 34 months; the average was 10 months. Four patients (59-103 days; an average of 80.5 days) died and two (313 days, 3331 days) survived. The causes of death were aggravation of the underlying disease (n = 2), pulmonary edema and pleural effusion (n = 1), and pneumonia (n = 1). Additional catheter drainage was performed in one patient, and a chest tube was maintained in two patients. Conclusion Bronchial occluders are useful and effective in the treatment of BPF after pulmonary resection.

• Journal of the Korea Computer Graphics Society
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• v.8 no.2
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• pp.9-14
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• 2002

In cases of densely occluded urban scenes, it is effective to determine the visibility of scenes, since only small parts of the scene are visible from a given cell. In this paper, we introduce a new visibility preprocessing method that efficiently computes potentially visible objects for volumetric cells. The proposed method deals with general 3D polygonal models and invisible objects jointly blocked by multiple occluders. The proposed approach decomposes volume visibility into a set of point visibilities, and then computes point visibility using hardware visibility queries, in particular HP_occlusion_test and NV_occlusion_query. We carry out experiments on various large-scale scenes, and show the performance of our algorithm.

• Clinical and Experimental Pediatrics
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• v.56 no.2
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• pp.90-93
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• 2013

Congenital coronary arteriovenous fistulas (CCAFs) are rare coronary artery abnormalities in which blood is shunted into a cardiac chamber or great vessel. If the fistula itself is large and tortuous, it is generally recommended to occlude the fistula to prevent several complications. In approaches of transcatheter occlusion, the transvenous approach is preferred over the transarterial approach. The transvenous approach would enable the cannulation of a relatively larger catheter or sheath without potential damage to the femoral vessels or normal coronary arteries, which can occur in the transarterial approach. The transvenous approach may also minimize the blind pouch after releasing the devices. Herein, we report the success of transvenous proximal closure of a CCAF using an Amplatzer vascular plug (AVP) in a 3-year-old patient with cardiomegaly. Complete occlusion was achieved by a single AVP and thrombus formation of the distal aneurysmal portion of the fistula. We suggest that this strategy of closing the proximal end with a dilated fistula using a single AVP by the transvenous approach may be a good option in treating CCAFs in a young child.