• International Journal of Vascular Biomedical Engineering
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• v.1 no.1
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• pp.13-23
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• 2003

Backgrounds: The present study in angulated coronary stenosis was to evaluate the influence of velocity and wall shear stress (WSS) on coronary atherosclerosis, the changes of hemodynamic indices following coronary stenting, as well as their effect of evolving in-stent restenosis using human in vivo hemodynamic parameters and computed simulation quantitatively and qualitatively. Methods: Initial and follow-up coronary angiographies in the patients with angulated coronary stenosis were performed (n=80). Optimal coronary stenting in angulated coronary stenosis had two models: < 50 % angle changed(model 1, n=43), > 50% angle changed group (model 2, n=37) according to percent change of vascular angle between pre- and post-intracoronary stenting. Flow-velocity wave obtained from in vivo intracoronary Doppler study data was used for in vitro numerical simulation. Spatial and temporal patterns of velocity vector and recirculation area were drawn throughout the selected segment of coronary models. WSS of pre/post-intracoronary stenting were calculated from three-dimensional computer simulation. Results: Follow-up coronary angiogram demonstrated significant difference in the percent of diameter stenosis between two groups (group 1: $40.3{\pm}30.2$ vs. group 2: $25.5{\pm}22.5%$, p<0.05). Negative WSS area on 3D simulation, which is consistent with re-circulation area of velocity vector, was noted on the inner wall of post-stenotic area before stenting. The negative WSS was disappeared after stenting. High spatial and temporal WSS before stenting fell into within physiologic WSS after stenting. This finding was prominent in Model 2 (p<0.01) Conclusions: The present study suggests that hemodynamic forces exerted by pulsatile coronary circulation termed as WSS might affect on the evolution of atherosclerosis within the angulated vascular curvature. Moreover, geometric change, such as angular difference between pre / post-intracoronary stenting might give proper information of optimal hemodynamic charateristics for vascular repair after stenting.

• Progress in Medical Physics
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• v.30 no.4
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• pp.75-88
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• 2019

Diagnostic reference level (DRL) is employed to optimize the radiation doses of patients. The objective of this study is to review the DRLs for interventional procedures in Korea and abroad. Literature review was performed to investigate radiation dose index and measurement methodology commonly used in DRL determination. Dose area product (DAP) and fluoroscopy time within each major procedure category were systematically abstracted and analyzed. A wide variation was found in the radiation dose. The DAP values and fluoroscopy times ranged 0.01-3,081 Gy·㎠ and 2-16,878 seconds for all the interventional procedures, 8.5-1,679 Gy·㎠ and 32-5,775 seconds for the transcatheter arterial chemoembolization (TACE), and 0.1-686 Gy·㎠ and 16-6,636 seconds for the transfemoral cerebral angiography (TFCA), respectively. The DRL values of the DAP and fluoroscopy time were 238 Gy·㎠ and 1,224 seconds for the TACE and 189 Gy·㎠ and 686 seconds for the TFCA, respectively. Generally, the DRLs of Korea were lower than those of other developed countries, except for the percutaneous transluminal angioplasty with stent in arteries of the lower extremity (LE PTA and stent), aneurysm coil embolization, and Hickman insertion procedures. The wide variation in the radiation doses of the different procedures suggests that more attention must be paid to reduce unnecessary radiation exposure from medical imaging. Furthermore, periodic nationwide survey of medical radiation exposures is necessary to optimize the patient dose for radiation protection, which will ultimately contribute to patient dose reduction and radiological safety.

• Biomedical Science Letters
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• v.19 no.1
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• pp.70-78
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• 2013

This study was conducted to identify the effects of intake of beta-blocker and aerobic exercise on heart rate recovery (HRR) and exercise capacity after maximal exercise in acute coronary syndrome patients (ACS). Subjects were divided into 4 groups; Beta-blocker-Exercise group (n=10), Beta-blocker group (n=10), Exercise group (n=10), Control group (n=10). Symptom-limited grade exercise test were conducted on subjects pre- and post- 6 week study, to measure maximal heart rate, heart rate at 1 minute and 2 minutes at the recovery stage, maximal oxygen uptake and maximal exercise time. Study resulted in significant improvements in heart rate recovery for BB-Ex group ($17.40{\pm}5.58$ bpm to $26.10{\pm}6.66$ bpm), maximal oxygen uptake for BB-Ex group ($30.46{\pm}8.63$ to $36.33{\pm}8.10$) and Ex group ($29.04{\pm}4.93$ to $34.31{\pm}5.19$), and total exercise time for BB-Ex group ($906.30{\pm}158.57$ to $1018.50{\pm}151.21$), BB group ($805.70{\pm}182.94$ to $897.50{\pm}160.16$) and Ex group ($870.00{\pm}145.63$ to $961.90{\pm}107.29$). Therefore it showed the biggest improvement for heart rate recovery and exercise capacity in acute coronary syndrome patients when both Beta-blocker and aerobic exercise were in effect.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.328-330
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• 2002

Large balloon angio catheter is used for Percutaneous Transluminal Angioplsty(TPA) of the iliac, femoral and renal arteries as well as after Transjugular Intrahepatic portosystemic shunt(TIPS). The use of angioplasty balloon filled with liquid form of radioisotope reduces the rate of restenosis after PTA. The purpose of this study was to evaluate the absorbed dose to the target vessels from various sized large balloon filled with liquid form of Ho-166-DTPA. Four balloons of balloon dilatation catheters evaluated were 5, 6, 8 and 10 mm in diameter. GafChromic film was used for the estimation of the absorbed dose near the surface of the balloon catheters. Absorbed dose rates are plotted in units of Gy/min/GBq/ml as a function of radial distance in mm from the surface of balloon. The absorbed dose rate was 1.1, 1.6, 2.2 and 2.3 Gy/min/GBq/ml at a balloon surface, 0.3, 0.4, 0.5 and 0.6 Gy/min/GBq/ml at 1 mm depth for various balloon diameter 5, 6, 8 and 10 mm in diameter respectively. The study was conducted to estimate the absorbed doses to the vessels from various sized large balloons filled with liquid form of Ho-166-DTPA for clinical trial of radiation therapy after the PTA. The absorbed dose distribution of Ho-166 appeared to be nearly ideal for vascular irradiation since beta range is very short avoiding unnecessary radiation to surrounding normal tissues.

• Journal of computational fluids engineering
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• v.22 no.1
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• pp.15-25
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• 2017

Swirl flow is often found in proximal coronary arteries, because the aortic valves can induce swirl flows in the coronary artery due to vortex formation. In addition, the curvature and tortuosity of arterial configurations can also produce swirl flows. The present study was performed to investigate fractional flow reserve alterations in a post-stenotic distal part due to the presence of pre-stenotic swirl flow by computational fluid dynamics analysis for virtual stenotic models by quantifying fractional flow reserve(FFR). Simplified stenotic coronary models were divided into those with and without pre-stenotic swirl flow. Various degrees of virtual stenosis were grouped into three grades: mild, moderate, and severe, with degree of stenosis of 0 ~ 40%, 50 ~ 60%, and 70 ~ 90%, respectively. In this study, three-dimensional computational hemodynamic simulations were performed under hyperemic conditions in virtual stenotic coronary models by coupling with a zero-dimensional lumped parameter model. The results showed that the influence of pre-stenotic swirl inflow is dominant on FFR alteration in mild stenosis, whereas stenosis is dominant on FFR alteration in moderate/severe stenosis. The decrease in FFR caused by swirl flow is more significant in mild stenosis than moderate/severe stenosis. Biomechanical modeling is useful for clinicians to provide insight for medical intervention strategies. This hemodynamic-based parameter study could play a critical role in the development of a non-invasive imaging-based strategy-support system for percutaneous transluminal angioplasty in cases of mild/moderate stenosis.

• Journal of Korean Foot and Ankle Society
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• v.17 no.1
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• pp.52-59
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• 2013

Purpose: The purpose of this study is to evaluate treatment results of multidisciplinary approach of critical ischemic limb with diabetic foot. Materials and Methods: From March 2005 to March 2012, 674 diabetic foot patients were analyzed. Among them, 85 patients were neuroarthropathic type, 383 patients were infectious type, and 206 patients were ischemic type. The subjects were 206 patients who had critical ischemic limbs and major or minor amputations were done. Various single or combined treatment method before amputation was performed. We investigated their ABI, HbA1c, main occlusion lesion, limb salvage and hospitalization period by various treatment method. Results: Major amputation was 27 cases, minor amputation was 179 cases. Mean HbA1c was 8.2%, and mean ABI was 0.66. Main occlusion lesion was 6 cases at common iliac artery, 13 cases at external iliac artery, 9 cases at internal iliac artery, 11 cases at common femoral artery, 23 cases at deep femoral artery, 52 cases at superficial femoral artery, 35 cases at popliteal artery, 40 cases at posterior tibia artery, 35 cases at anterior tibial artery, 28 cases at peroneal artery, and 13 cases at dorsalis pedis artery. Major amputations were decreased, minor amputations were increased, and hospitalization period was reduced by treatment of multidisciplinary approach. Conclusion: Treatment of multidisciplinary approach, which include preoperation percutaneus transluminal angioplasty, vascular surgery, and amputation, of critical ischemic limb with diabetic foot had advantages of limb salvage and hospitalization period reduction.

• Journal of Preventive Medicine and Public Health
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• v.50 no.1
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• pp.29-37
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• 2017

Objectives: The accurate measurement of geographic patterns of health care utilization is a prerequisite for the study of geographic variations in health care utilization. While several measures have been developed to measure how accurately geographic units reflect the health care utilization patterns of residents, they have been only applied to hospitalization and need further evaluation. This study aimed to evaluate geographic indices describing health care utilization. Methods: We measured the utilization rate and four health care utilization indices (localization index, outflow index, inflow index, and net patient flow) for eight major procedures (coronary artery bypass graft surgery, percutaneous transluminal coronary angioplasty, surgery after hip fracture, knee replacement surgery, caesarean sections, hysterectomy, computed tomography scans, and magnetic resonance imaging scans) according to three levels of geographic units in Korea. Data were obtained from the National Health Insurance database in Korea. We evaluated the associations among the health care utilization indices and the utilization rates. Results: In higher-level geographic units, the localization index tended to be high, while the inflow index and outflow index were lower. The indices showed different patterns depending on the procedure. A strong negative correlation between the localization index and the outflow index was observed for all procedures. Net patient flow showed a moderate positive correlation with the localization index and the inflow index. Conclusions: Health care utilization indices can be used as a proxy to describe the utilization pattern of a procedure in a geographic unit.

• Journal of Chest Surgery
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• v.26 no.1
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• pp.32-35
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• 1993

During the period from September 1989 through December 1992, 118 cases of coronary arterial bypass graft were performed at Department of Cardiothoracic Surgery, Asan Medical Center. Twenty-one of these had history of recent or remote percutaneous transluminal coronary angioplasty. They consisted of 13 males[age,58.7 + 5.4 years] and 8 females[age, 63.6 + 2.8years] with the mean age of 60.6. History of old myocardial infarction was noted in 24%[5/21] of the patients and congestive heart failure in 2 cases. The angina by type of presentation is unstable in all of the patients. The patterns of involvement of coronary arterial disease were left main disease[1], single vessel disease[5], double vessel involvement[10], and triple vessel involvement[5]. We performed 4 cases of single bypasses, 7 cases of double, 8 cases of triple, and 2 cases of quadruple bypasses. Total of 51 grafts[LIMA:12, RSVG:39] were inserted in 21 cases with average of 2.4 grafts per patient. The methods of myocardial protection were cold blood cardioplegia[8 cases], intermittent aortic occlusion[11], and continuous coronary perfusion with local coronary sharing[2]. There were no operative or late death. The only cardiac complication was 1 case of low cardiac output required IABP. The other complications were 1 case of sternal wound infection and 1 case of postoperative bleeding required reoperation. And there was no case of perioperative myocardial infarction. Postoperatively, 3 cases of recurrent angina were detected at 5, 7, and 18months after surgery. One of them was managed successfully with repeat PTCA[who was recurred 18 months postoperatively], and the other two with medication. I conclude that we can approach the patients more aggressively with PTCA, because of our acceptable operative risks.

• The Korean Journal of Nuclear Medicine
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• v.24 no.2
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• pp.325-331
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• 1990

Radionuclide renal scintigraphies were performed in a 24-year-old man with right renal artery branch stenosis. Captopril enhanced $^{99m}Tc-DTPA$ renal scintigraphy revealed no abnormal finding in the right kidney. But, $^{99m}Tc-DMSA$ renal scintigraphy showed regional cortical photon deficient area corresponding to the area supplied by the stenotic branch artery. The defect size increased in captopril enhanced $^{99m}Tc-DMSA$ renal scintigrphy and nearly disappeared after successful transluminal renal angioplasty. This case suggests that the captopril enhanced $^{99m}Tc-DMSA$ renal scintigraphy may be a useful method in the evaluation of renovascular hypertension, especially due to branch renal srtery stenosis.

• Journal of Chest Surgery
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• v.36 no.5
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• pp.363-366
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• 2003

Background: Left ventricular rupture after acute myocardial infarction is a serious complication with high mortality. Emergency operation is usually the only available treatment. A 76-year-old female with persistent chest pain and syncopal attacks was admitted. Transthoracic echocardiography showed the pericardial effusion and generalized hypokinesia of the inferolateral wall of left ventricle. Coronary angiography revealed a total occlusion of the first diagonal branch. After percutaneous transluminal coronary angioplasty with coronary stent and insertion of intraaortic balloon pump, emergency operation was performed. Under cardiopulmonary bypass and cardiac arrest with cold blood cardioplegia, coronary artery bypass graft with saphenous vein, pericardial patch covering on the rupture area with 6-0 polypropylene running sutures, and fibrin glue compression under the patch were performed. We present a case of left ventricular (free wall) rupture after acute myocardial infarction.