• Journal of Chest Surgery
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• v.27 no.8
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• pp.669-676
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• 1994

Because the number of patients who require maintenance hemodialysis is increasing in number recently, angioaccess has become important to many vascular surgeons participating in the management of such patients.The authors created 269 arteriovenous fistulas[AVF] for angioaccess in 229 patients with chronic renal failure[CRF] at the Department of Thoracic and Cardiovascular Surgery in Chungnam National University Hospital during the period from August 1990 to March 1993. We analyzed the results of 260 operations for 220 patients except 9 patients who were lost during the follow up period. We performed snuffbox AVF in 171 cases, classic radiocephalic AVF in 46 cases, direct AVF at other site in 5 cases, forearm Gore-Tex AVF in 29 cases, and upper arm Gore-Tex AVF in 9 cases. We experienced 13 cases of operative failures, 11 cases of early complications, and 60 cases of late complications including obstructions during follow-up period. The 1 year, 2 year and 3 year patency rates of snuffbox AVF[Group 1], classic radiocephalic AVF[Group 2], and Gore-Tex AVF[Group 3] are like followings; 89, 84, 76% in group 1, 84, 75, 68% in group 2, and 79, 66, 55% in group 3. It showed a statistically significant difference between group 1, 2 and group 3.

• Journal of Chest Surgery
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• v.48 no.1
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• pp.46-51
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• 2015

Background: Maintenance of adequate vascular access for hemodialysis is important in patients with end-stage renal disease. Once arteriovenous fistula (AVF) occlusion occurs, the patient should be treated with rescue therapy. This study was performed to evaluate the results of a rescue therapy for AVF occlusion. Methods: From January 2008 to December 2012, 47 patients who underwent surgical rescue therapy for AVF occlusion after graft AVF formation, were enrolled in this study. The patients were divided into two groups, namely the graft repair group (group A, n=19) and the thrombectomy group (group B, n=28). Postoperative results of both groups were analyzed retrospectively. Results: There were no statistically significant differences in the clinical characteristics between the two groups. In terms of the duration of AVF patency after the first rescue therapy, group A showed a longer AVF patency duration than group B ($24.5{\pm}21.9$ months versus $17.7{\pm}13.6$ months), but there was no statistically significant difference (p=0.310). In terms of the annual frequency of AVF occlusion after the rescue therapy of group A was lower than that of group B (0.59 versus 0.71), but there was no statistically significant difference (p=0.540). The AVF patency rates at 1, 2, 3, and 5 years after the first rescue therapy in group A were 52.6%, 31.5%, 21.0%, and 15.7%, respectively, and those in group B, they were 32.1%, 25.0%, 17.8%, and 7.14%, respectively. There was no statistically significant difference (p=0.402). Conclusion: Graft repair revealed comparable results. Although there was no statistically significant difference, the patent duration and annual frequency of AVF occlusion of group A were better than those of group B. Therefore, graft repair is considered as a safe and useful procedure for maintaining graft AVF.

• Journal of Korean Neurosurgical Society
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• v.56 no.2
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• pp.168-170
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• 2014

Dural arteriovenous fistula (AVF) is very rare, acquired lesion that may present with intracranial hemorrhage or neurological deficits. The etiology is not completely understood but dural AVF often has been associated with thrombosis of the involved dural sinuses. To our knowledge, this is the first well documented intracranial hemorrhage case caused by dural AVF following microvascular decompression for hemifacial spasm. A 49-year-old male patient had left microvascular decompression of anterior inferior cerebellar artery via retrosigmoid suboccipital craniotomy. The patient was in good condition without any residual spasm or surgery-related complications. However, after 10 months, he suffered sudden onset of amnesia and dysarthria. Computed tomography and magnetic resonance imaging revealed the presence of dural AVF around the left transverse-sigmoid sinus. The dural AVF was treated with Onyx$^{(R)}$ (ev3) embolization. At the one-year follow up visit, there were no evidence of recurrence and morbidity related to dural AVF and its treatment. This case confirms that the acquired etiology of dural AVF may be associated with retrosigmoid suboccipital craniotomy for hemifacial spasm, even though it is an extremely consequence of this procedure.

• Journal of Chest Surgery
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• v.53 no.6
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• pp.408-410
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• 2020

Iatrogenic vascular injuries may occur during venipuncture, arterial cannulation, or catheterization procedures. Brachial arteriovenous fistula (AVF) resulting from antecubital vascular access is rare and develops slowly. We report the case of an 18-year-old man who had developed iatrogenic brachial AVF. He had a history of several venipunctures in the left arm at the age of 10 months. Doppler ultrasonography and computed tomographic angiography were used to establish a diagnosis of brachial AVF, and surgical correction of the AVF was performed. As our case indicates, delayed surgery can be considered as a treatment option and may be associated with a decreased risk of vascular complications in the management of iatrogenic brachial AVF in infants.

• Journal of Korean Neurosurgical Society
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• v.44 no.2
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• pp.101-104
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• 2008

Intracranial pial arteriovenous fistula (AVF) is a rare cerebrovascular lesion that has only recently been recognized as a distinct pathological entity. A 41-year-old woman (Patient 1) presented with the sudden development of an altered mental state. Brain CT showed an acute subdural hematoma. A red sylvian vein was found intraoperatively. A pial AVF was revealed on postoperative angiography, and surgical disconnection of the AVF was performed. A 10-year-old boy (Patient 2) presented with a 10-day history of paraparesis and urinary incontinence. Brain, spinal MRI and angiography revealed an intracranial pial AVF and a spinal perimedullary AVF. Endovascular embolization was performed for both lesions. The AVFs were completely obliterated in both patients. On follow-up, patient 1 reported having no difficulty in performing activities of daily living. Patient 2 is currently able to walk without assistance and voids into a diaper. Intracranial pial AVF is a rare disease entity that can be treated with surgical disconnection or endovascular embolization. It is important for the appropriate treatment strategy to be selected on the basis of patient-specific and lesion-specific factors in order to achieve good outcomes.

• Journal of the Korean Society of Visualization
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• v.14 no.1
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• pp.33-39
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• 2016

Radio-cephalic arteriovenous fistula(RC-AVF) is the most recommended operation of achieving access for hemodialysis. However, it has high rates of early failure depending on the many haemodynamic conditions. To increase RC-AVF patency rate, many researches were performed by in-vitro experiment via artificial vessel and blood analogue fluid, and there were conflicting opinions about whether the non-Newtonian properties of blood have an influence on the flow in large arteries. To investigate the influence of viscoelasticity of blood within the RC-AVF, we fabricated three dimensional artificial RC-AVF and two kinds of blood analogue fluid. The velocity field of two fluids within the vessel were measured by micro-particle velocimetry(m-PIV) and compared with each other. The velocity profiles of both fluids for systolic phase were matched well while those for diastolic phase did not correspond. Therefore, it is desired to use non-newtonian fluid for in-vitro experiment of RC-AVF.

• Korean Journal of Radiology
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• v.23 no.10
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• pp.949-958
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• 2022

Objective: To investigate the feasibility of using a deep learning-based analysis of auscultation data to predict significant stenosis of arteriovenous fistulas (AVF) in patients undergoing hemodialysis requiring percutaneous transluminal angioplasty (PTA). Materials and Methods: Forty patients (24 male and 16 female; median age, 62.5 years) with dysfunctional native AVF were prospectively recruited. Digital sounds from the AVF shunt were recorded using a wireless electronic stethoscope before (pre-PTA) and after PTA (post-PTA), and the audio files were subsequently converted to mel spectrograms, which were used to construct various deep convolutional neural network (DCNN) models (DenseNet201, EfficientNetB5, and ResNet50). The performance of these models for diagnosing ≥ 50% AVF stenosis was assessed and compared. The ground truth for the presence of ≥ 50% AVF stenosis was obtained using digital subtraction angiography. Gradient-weighted class activation mapping (Grad-CAM) was used to produce visual explanations for DCNN model decisions. Results: Eighty audio files were obtained from the 40 recruited patients and pooled for the study. Mel spectrograms of "pre-PTA" shunt sounds showed patterns corresponding to abnormal high-pitched bruits with systolic accentuation observed in patients with stenotic AVF. The ResNet50 and EfficientNetB5 models yielded an area under the receiver operating characteristic curve of 0.99 and 0.98, respectively, at optimized epochs for predicting ≥ 50% AVF stenosis. However, Grad-CAM heatmaps revealed that only ResNet50 highlighted areas relevant to AVF stenosis in the mel spectrogram. Conclusion: Mel spectrogram-based DCNN models, particularly ResNet50, successfully predicted the presence of significant AVF stenosis requiring PTA in this feasibility study and may potentially be used in AVF surveillance.

• Journal of Korean Neurosurgical Society
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• v.57 no.3
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• pp.204-207
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• 2015

We are reporting an unusual case of dural arteriovenous fistula (AVF) of the superior sagittal sinus (SSS) after tamoxifen treatment for breast cancer. A 30-year-old female arrived at the emergency room with a sudden headache and left sided weakness and sensory loss. In her past medical history, she was diagnosed with breast cancer 1 year prior, and subsequently underwent a breast conserving mastectomy with whole breast radiation and adjuvant chemotherapy with tamoxifen. At the time of admission, computed tomography showed a small acute intracerebral hemorrhage at the right parietal cortex, and magnetic resonance imaging showed that a dural AVF at the SSS with a prominent and tortuous venous enhancement along the centrum semiovale was present. Cerebral angiography showed that the dural AVF at the mid-portion of the SSS with meningeal arterial feeding vessels entering the wall of the SSS, then draining through the dilated cortical veins. Our patient had no signs of active malignancy or any abnormalities in her coagulation profile, so it can be concluded that the tamoxifen was the likely cause of the SSS thrombosis and dural AVF. The dural AVF was treated by an endovascular coil embolization for the arterialized segment of the SSS. The patient dramatically recovered favorably from left side motor and sensory deficit. The best clinical approach is to screen potential patients of tamoxifen hormonal therapy and educate them on the sign and symptoms of life threatening thromboembolic events while taking tamoxifen.

• The Journal of the Acoustical Society of Korea
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• v.12 no.1
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• pp.37-46
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• 1993

The adaptive algorithm for the Volterra filter is considered. Owing to its simplicity, the LMS algorithm for adaptive Volterra filter(AVF) is widely used as in linear adaptive filters. However, the convergence speed is unsatisfactory. For improving the convergence speed, the frequency domain LMS second order adaptive Volterra filter(FLMS-AVF) is proposed and analyzed. We show that the time and frequency domain LMS AVF's have the same steady state performance under approprate conditons. Moreover, it can be shown that this algorithm can improve the convergence speed significantly by applying self-orthogonalizing method.

• Journal of Trauma and Injury
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• v.26 no.3
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• pp.248-251
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• 2013

Introduction: A post-traumatic mesenteric arteriovenous fistula (AVF) is extremely rare. Case Report: A previously healthy 26-year-old male was injured with an abdominal stab wound. Computed tomography (CT) showed liver injury, pancreas injury and a retropancreatic hematoma. We performed the hemostasis of the bleeding due to the liver injury, a distal pancreatectomy with splenectomy and evacuation of the retropancreatic hematoma. On the 5th postoperative day, an abdominal bruit and thrill was detected. CT and angiography showed an AVF between the superior mesenteric artery (SMA) and the inferior mesenteric vein with early enhancement of the portal vein (PV). The point of the AVF was about 4 cm from the SMA's orifice. After an emergent laparotomy and inframesocolic approach, the isolation of the SMA was performed by dissection and ligation of adjacent mesenteric tissues which was about 6 cm length from the nearby SMA orifice, preserving the major side branches of the SMA, because the exact point of the AVF could not be identified despite the shunt flow in the PV being audible during an intraoperative hand-held Doppler-shift measurement. After that, the shunt flow could not be detected by using an intraoperative hand-held Doppler-shift measuring device. CT two and a half months later showed no AVF. There were no major complications during a 19-month follow-up period. Conclusion: Early management of a post-traumatic mesenteric AVF is essential to avoid complications such as hemorrhage, congestive heart failure and portal hypertension.