• The Korean Journal of Nuclear Medicine
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• v.26 no.1
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• pp.40-48
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• 1992

Gated blood pool scan is frequently used for evaluating the change in cardiac function in various cardiac diseases. But resting gated blood pool scan using only LVEF as a cardiac index has been consitently shown to have a low sensitivity, which is about 50%, in detecting coronary artery disease. So it is recommended to compare exercise gated blood pool scan to resting gated blood pool scan. Exercise tests, however, are not always possible, especially in patients with musculoskeletal diseases, recent myocardial infarction and in elderly persons. We studied the usefulness of resting gated blood pool scan using multiple indices in evaluating the patients with coronary artery disease. Studied cases were 185 patients with coronary artery disease (angina pectoris 31, myocardial infarction 154) and 25 normals with low likelihood of coronary artery disease. We used $^{99m}Tc-labeled$ RBC, 740 MBq labeled by in vivo method. The data were evaluated by Micro DELTA computer program. The results were as following: 1) The ejection rates (PER, AER) and filling rates (PFR, AFR) were different in normls and patients with angina pectoris or myocardial infarction. 2) Mean phase angle, ejection rates and filling rates could separate normals from coronary artery disease patients with normal LVEF. 3) Regional ejection fraction was decreased at the site of the infarct in patients with myocardial infarction. 4) Peak filling rate was the the most detectable index in evaluation of cardiac function in patients with coronary artery disease. 5) The threshold at 1.5 standard deviation of normal range was considered as the most reliable cut-off value from ROC analysis. These data suggest that the resting gated blood pool scan has an important role in the evaluation of cardiac functional changes using various cardiac indices in patients with coronary artery disease.

• Journal of the Korean Society of Safety
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• v.27 no.5
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• pp.35-41
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• 2012

The Numerical simulation was performed on the flow field around the two-dimensional rectangular bluff body in order to complement the previous experimental results of the bluff body stabilized flames [1]. For both fuel ejection configurations against an oxidizer stream, the flame stability was affected mainly by vortex structure and mixing field near bluff body. FDS(Fire Dynamic Simulator) based on the LES(Large Eddy Simulation) was employed to clarify the isothermal mixing characteristic and wake flow pattern around bluff body. The air used atmosphere and the fuel used methane. The result of counter flow configuration shows that the flow field depends on air velocity but the mixing field is influenced on the fuel velocity. At low fuel velocity the fuel mole fraction is below the flammable limit and hence the mixing is insufficient to react. Therefore, as the result, the flame formed at low fuel velocity is characterized by non-premixed flames. For the flow field of co-flow configuration, flame stability was affected by fuel velocity as well as air velocity. the vortex generated by fuel stream has counter rotating direction against the air stream. Therefore, the momentum ratio between air and fuel stream was important to decide the flame blow out limit, which is result in the characteristic of the partially premixed reacting wake near extinction.

• Korean Journal of Adult Nursing
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• v.23 no.3
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• pp.244-254
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• 2011

Purpose: The objective of this study was to evaluate adherence to self-care and identify associated factors in outpatients with Heart Failure (HF). Methods: Using a cross-sectional design, a convenience sample of 249 outpatient clinic patients were recruited at S university hospital. Between October 2009 and December 2009, data were collected through questionnaires and medical record review. Results: The total mean score of adherence to self-care was $18.07{\pm}3.56$ out of a possible 45 points. Among self-care dimensions, adherence to medication and low salt diet was high, while lower adherence was reported in contact with health professionals if symptoms such as weight gain, edema and fatigue were presented. Multivariate analysis adjusted for other socio-demographic and clinical factors showed that disease knowledge related to heart failure (p<.001) and left ventricular ejection fraction (p=.027) were independent predictors of adherence to self-care. These factors explained 23% of total variance in the adherence to self-care. Conclusion: Heart failure patients with higher disease knowledge and those who have good systolic function may be more likely to engage in adherence to self-care than those with lack of disease knowledge and low contractility. Further research is needed to confirm these results and identify other predictors of adherence to self-care.

• Journal of Chest Surgery
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• v.47 no.3
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• pp.233-239
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• 2014

Background: As hypertrophied myocardium predisposes the patient to decreased tolerance to ischemia and increased reperfusion injury, myocardial protection is of utmost importance in patients undergoing aortic valve replacement (AVR) for severe aortic valve stenosis (AS). Methods: Consecutive 314 patients (mean age, $62.5{\pm}10.8$ years; 143 females) with severe AS undergoing isolated AVR were included. Postoperative myocardial injury (PMI) was defined as 1) maximum postoperative creatinine kinase isoenzyme MB or troponin-I levels ${\geq}10$ times of reference, 2) postoperative low cardiac output syndrome or episodes of ventricular arrhythmia, or 3) left ventricular ejection fraction of less than 55% and decrease in left ventricle (LV) ejection fraction of more than 20% of the baseline value. Results: There were 90 patients (28.7%) who developed PMI. There were five cases of early death (1.6%), all of whom had PMI. On multivariable analysis, the use of histidine-tryptophan-ketoglutarate (HTK) solution instead of blood cardioplegia (odds ratio [OR], 3.06; 95% confidence interval [CI], 1.63 to 5.77; p=0.001), greater LV mass (OR, 1.04; 95% CI, 1.01 to 1.07; p=0.007), and increased cardiac ischemic time (OR, 1.13; 95% CI, 1.05 to 1.22; p<0.001) were independent predictors for PMI. Patients who had PMI showed significantly inferior long-term survival than those without PMI (p=0.049). Conclusion: PMI occurred in a considerable proportion of patients undergoing AVR for severe AS and was associated with poor long-term survival. HTK cardioplegia, higher LV mass, and longer cardiac ischemic duration were suggested as predictors of myocardial injury.

• Journal of Chest Surgery
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• v.56 no.3
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• pp.197-203
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• 2023

Background: The survival benefit of coronary artery bypass grafting (CABG) using the bilateral internal thoracic arteries (BITA) is well known; however, the role of BITA in concomitant aortic valve replacement (AVR) and CABG has not been studied. Methods: We retrospectively reviewed patients who underwent concomitant AVR and CABG. Cases not using an internal thoracic artery and less than 2 bypass grafts were excluded. We enrolled 114 patients in this study. The mean follow-up duration was 61.5±43.5 months. Results: Forty patients (35.1%) underwent CABG with a single internal thoracic artery (SITA) and 74 patients (64.9%) underwent CABG with BITA. The preoperative clinical characteristics were not significantly different between the 2 groups, with the exception of a higher prevalence of atrial fibrillation in the SITA group. Postoperative mortality and morbidity were not significantly higher in the BITA group than in the SITA group. In the univariable analysis, the survival of the BITA group was similar to that of the SITA group (p=0.157). Multivariable analysis showed that only mean age was a predictor of death (p=0.042), but using BITA was not an independent predictor (p=0.094). In low-risk patients whose preoperative ejection fraction was >45%, the survival of the BITA group was significantly better than that of the SITA group (p=0.043). Conclusion: BITA use in concomitant AVR and CABG showed no difference in mortality compared to using SITA. Although its impact on long-term survival was inconclusive, BITA use can be considered for low-risk patients.

• Journal of Chest Surgery
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• v.40 no.8
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• pp.552-557
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• 2007

Background: B-type natriuretic peptide (BNP) is a cardiac hormone that is primarily synthesized by the ventricular cardiac myocytes. Increased plasma BNP levels have been observed in patients suffering with congestive heart failure, ventricular hypertrophy and myocaridits and also during heart transplantation rejection. We investigated the serum BNP level as a predictive marker for rejection after heart transplantation. Material and Method: To test the usefulness of measuring the BNP level in cardiac transplant patients, consecutive blood samplings for BNP, right ventricular endomyocardial biopsies, hemodynamic measurements and transthoracic echocardiogram were all done in 10 such patients between January 2004 and August 2005 at the Department of Thoracic and Cardiovascular Surgery in Asan Medical Center. Two groups were identified with using the median value: the low BNP group (n=28, BNP: ${\le}290$ pg/mL) and the high BNP group (n=29, BNP: >290 pg/mL). We retrospectively analyzed rejection, the ejection fraction, tricuspid regurgitation, left ventricular hypertrophy, the pulmonary capillary wedge pressure and the right atrial pressure between the 2 groups. Result: There were no differences in age, gender, rejection, the ejection fraction, tricuspid regurgitation, left ventricular hypertrophy and the right atrial pressure between the 2 groups (p>0.05). However, a higher pulmonary capillary wedge pressure and a higher mean pulmonary atrial pressure were observed in the high BNP group (p<0.05). Further, BNP has linear correlation with the pulmonary capillary wedge pressure (r=0.590, p<0.001). Using the cut-off value of 620 pg/mL, the BNP predicted a high PCWP (>12 mmHg) with a sensitivity of 83.3% and a specificity of 91.1% (AUC: $0.900{\pm}0.045$, p<0.001). Conclusion: The BNP level after heart transplantation does not show any significant correlation with rejection, yet it might be a predictive marker of ventricular diastolic dysfunction.

• Korean Journal of Clinical Laboratory Science
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• v.37 no.2
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• pp.88-95
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• 2005

Even though the echocardiograph has been recognized as the method of choice among various diagnostic tools to detect congestive heart failure (CHF), there were some limitations in relation to the consumption of time, labor and process. We analyzed results of N-terminal probrain-type natriuretic peptide (NT-proBNP) and various parameters of the echocardiographic findings to clarify the diagnostic usefulness of NT-proBNP in detecting patients with CHF. We analyzed the sera from total of 242 cases from in-patients and out-patients, which were requested from the cardiovascular section of department of Internal Medicine at Chungnam National University Hospital from March 2003 to May 2004. The procedures were performed in order as shown below; sampling, NT-proBNP analysis, data acquisition and data analysis. All data including personal information and echocardiographic findings ware acquired by medical record review. When classifying the study population into six groups according to the degree of left ventricular ejection fraction (LVEF), the serum level of NT-proBNP was higher in the group with 51-60% of LVEF (P=0.023). There were low correlation between the serum level of NT-proBNP and various parameters of the echocardiographic findings with LVESD (r=0.1513), LVEDD (r=0.0831), LVEF (r=0.2035), IVST (r=0.03) and LVPWT (r=0.0728), respectively. When comparing NT-proBNP with atrial and/or ventricular enlargement, the patient group with both left atrial and left ventricular enlargement (p=0.186) or only left atrial (p=0.105) or only left ventricular enlargement (p=0.256) showed higher level of NT-proBNP without statistical significance than patient group with no enlargement. Searching the optimal cutoff of the serum level of NT-proBNP, the sensitivity (98.9%) and the specificity (100%) was highest at the cutoff of 300 pg/mL than any other cutoffs. These findings suggested that the analysis of NT-proBNP in serum might detect the patients with CHF earlier than with the echocardiograph, especially in patients with asymptomatic or mild symptomatic CHF. In conclusion, NT-proBNP test was proved to be clinically useful to diagnose CHF patients.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.43.1-43.1
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• 2018

Star formation in galaxies predominantly takes place in giant molecular clouds (GMCs). While it is widely believed that UV radiation feedback from young massive stars can destroy natal GMCs by exciting HII regions and driving their expansion, our understanding on how this actually occurs remains incomplete. To quantitatively assess the effect of UV radiation feedback on cloud disruption, we conduct a series of theoretical studies on the dynamics of HII regions and its role in controlling the star formation efficiency (SFE) and lifetime of GMCs in a wide range of star-forming environments. We first develop a semi-analytic model for the expansion of spherical dusty HII regions driven by the combination of gas and radiation pressures, finding that GMCs in normal disk galaxies are destroyed by gas-pressure driven expansion with SFE < 10%, while more dense and massive clouds with higher SFE are disrupted primarily by radiation pressure. Next, we turn to radiation hydrodynamic simulations of GMC dispersal to allow for self-consistent star formation as well as inhomogeneous density and velocity structures arising from supersonic turbulence. For this, we develop an efficient parallel algorithm for ray tracing method, which enables us to probe a range of cloud masses and sizes. Our parameter study shows that the net SFE, lifetime (measured in units of free-fall time), and the importance of radiation pressure (relative to photoionization) increase primarily with the initial surface density of the cloud. Unlike in the idealized spherical model, we find that the dominant mass loss mechanism is photoevaporation rather than dynamical ejection and that a significant fraction of radiation escapes through low optical-depth channels. We will discuss the astronomical.

• Journal of Chest Surgery
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• v.49 no.1
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• pp.9-14
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• 2016

Background: Tetralogy of Fallot (TOF) is a well-recognized congenital heart disease. Despite improvements in the outcomes of surgical repair, the optimal timing of surgery and type of surgical management of patients with TOF remains controversial. The purpose of this study was to assess outcomes following the repair of TOF in infants depending on the surgical procedure used. Methods: This study involved the retrospective review of 120 patients who underwent TOF repair between 2010 and 2013. Patients were divided into three groups depending on the surgical procedure that they underwent. Corrective surgery was done via the transventricular approach (n=40), the transatrial approach (n=40), or a combined atrioventricular approach (n=40). Demographic data and the outcomes of the surgical procedures were compared among the groups. Results: In the atrioventricular group, the incidence of the following complications was found to be significantly lower than in the other groups: complete heart block (p=0.034), right ventricular failure (p=0.027) and mediastinal bleeding (p=0.007). Patients in the atrioventricular group had a better postoperative right ventricular ejection fraction (p=0.001). No statistically significant differences were observed among the three surgical groups in the occurrence of tachycardia, renal failure, and tricuspid incompetence. The one-year survival rates in the three groups were 95%, 90%, and 97.5%, respectively (p=0.395). Conclusion: Combined atrioventricular repair of TOF in infancy can be safely performed, with acceptable surgical risk, a low incidence of reoperation, good ventricular function outcomes, and an excellent survival rate.

• Journal of Cardiovascular Imaging
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• v.30 no.1
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• pp.25-34
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• 2022

BACKGROUND: The purpose of this study was to assess the utility of a handheld device (HH) used during common daily practice and its agreement with the results of a standard echocardiography study (STD) performed by experienced sonographers and echocardiographer. METHODS: A prospective follow-up was conducted in an adult outpatient echocardiography clinic. Experienced sonographers performed the STD and an experienced echocardiographer performed the HH. STD included 2-dimensional images, Doppler and hemodynamics analysis. Hemodynamic assessment was not performed with the HH device because the HH does not include such technology. The images were interpreted by blinded echocardiographers, and the agreement between the reports was analyzed. RESULTS: A total of 108 patients were included; and the concordance for left ventricle (LV) ejection fraction (EF), wall motion score index, LV and right ventricle (RV) function, RV size, and mitral and aortic stenosis was excellent with κ values greater than 0.80. Wall motion abnormalities had good concordance (κ value 0.78). The agreement for LV hypertrophy, mitral and aortic regurgitation was moderate, and tricuspid and pulmonary regurgitation agreements were low (κ values of 0.26 and 0.25, respectively). CONCLUSIONS: In a daily practice scenario with experienced hands, HH demonstrated good correlation for most echocardiography indications, such as ventricular size and function assessment and stenosis valve lesion analyses.