• Journal of radiological science and technology
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• v.31 no.4
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• pp.379-387
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• 2008

Among methods to eliminate aliasing effects, the method of increasing velocity scale gradually eliminated the phenomenon in which the direction of the blood flow appeared in reverse. It was done by increasing the velocity scale while maintaining other parameters in the same state. The method of setting the Doppler angle to $0^{\circ}$ did not show significant changes in the wave pattern of the spectrum according to the angle. In actual ultrasonography tests, more accurate tests are expected to be carried out by applying variations to the velocity scale under the considerations of speed, accuracy, and convenience of the examination. The results showed that blood flow velocity increases exponentially according to the Doppler Angle. When the angle goes over $70^{\circ}$, the velocity value increases to an unmeasurable state. This indicates that in blood flow velocity measurements, the blood flow velocity is very dependent on the Doppler Angle. It also shows that the error increases when the incidence angle to the direction of blood flow exceeds $60^{\circ}$, and when the angle exceeds $70^{\circ}$, the error becomes even greater. In addition, he experiment results showed that an angle below $60^{\circ}$ is appropriate and for blood flow velocity measurements in extremity vessels, the most appropriate Doppler Angle is from $45^{\circ}$ to $60^{\circ}$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.8
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• pp.84-87
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• 2017

Cerebral hyperperfusion syndrome (CHS) is a rare complication that can occur when conducting stent insertion or endarterectomy in patients with carotid artery stenosis and is known to be caused by various mechanisms when the blood volume abruptly increases. The main clinical symptoms are unilateral headache, hypertension, seizure, and focal neurologic deficit. Subarachnoid hemorrhage and parenchymal hemorrhage may lead to permanent impairment or death in severe cases. CHS can be predicted by using transcranial Doppler, perfusion magnetic resonance imaging, and single photon emission computed tomography. In our case report, a patient developed CHS subsequent to significant venous congestion caused by carotid artery stent insertion. The patient had preexisting, symptomatic bilateral carotid artery stenosis. Venous congestion occurs when the direction of blood flow changes because of increased blood volume in patients with well-developed collateral vessels. We believe that CHS can be predicted from this finding. This study reports the possibility that CHS could be confirmed by cerebral angiography after insertion of the internal carotid stent.

• Journal of Veterinary Clinics
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• v.31 no.5
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• pp.367-370
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• 2014

The study was to observe hemodynamic alterations of cardiac function to design a model of canine mitral valve insufficiency (MVI) based on chordae tendinae rupture (CTR). Ten healthy beagles with normal heart function were used in this study. To measure hemodynamics, the patient monitor was equipped for invasive blood pressure and a Swan-Ganz catheter. Hemodynamic alterations were checked promptly during CTR procedures. MVI model was made by transection of the chordae tendinae with small arthroscopy hook knife through $5^{th}$ intercostal open chest. Color Doppler at the level of the mitral valve showed high-velocity regurgitant flow immediately after CTR at intraoperative echocardiography. In hemodynamic measurements, pulmonary capillary wedge pressure (PCWP) was significantly increased, while mean arterial pressure (MAP), venous pressure (VP), pulmonary arterial pressure (PAP), cardiac output (CO) and cardiac index (CI) were significantly decreased after CTR. It was known that the left atrium was overloaded by regurgitant volume from the left ventricle. In conclusion, the MVI model induced by CTR technique in this study should be used as suitable one for the effective research of canine mitral valve disease. Further study should be needed to measure the chronic alternation of mitral valve in the model.

• Journal of the Korea Convergence Society
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• v.10 no.6
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• pp.79-87
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• 2019

This study examined how the application of silver spike point (SSP) and acupuncture-like transcutaneous electrical nerve stimulation (A-TENS) on acupoints affects blood flow and pain threshold, using laser Doppler blood fluxes and the Commander algometer. Our study included 32 healthy men and women who were randomly divided into the SSP group (n=18) and the A-TENS group (n=14). The pain threshold and blood flow were measured at the Neiguan (PC6) of the Jueyin Pericardium Meridian of the hand. SSP was performed with a 2.8cm electrode at a fixed frequency of 3 Hz for 15 minutes. The change in blood flow and pain threshold after the intervention significantly differed between the two groups (p<0.05). We found that the application of SSP and A-TENS on an acupoint altered their blood flow and pressure pain threshold, with SSP resulting in significantly greater change than A-TENS. Based on these results, the convergence of acupoint and electrical stimulation therapy can be usefully applied as a method for various patients. Continued development of convergence interventions is necessary.

• Journal of Korea Water Resources Association
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• v.54 no.3
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• pp.181-190
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• 2021

In this study, a large-scale levee breach experiment from lateral overflow was conducted to verify the effect of the new reinforcement method applied to the levee's surface. The new method could prevent levee failure and minimize damage caused by overflow in rivers. The levee was designed at the height of 2.5 m, a length of 12 m, and a slope of 1:2. A new material mixed with biopolymer powder, water, weathered granite, and loess in an appropriate ratio was sprayed on the levee body's surface at a thickness of about 5 cm, and vegetation recruitment was also monitored. At the Andong River Experiment Center, a flow (4 ㎥/s) was introduced from the upstream of the A3 channel to induce the lateral overflow. The change of lateral overflow was measured using an acoustic doppler current profiler in the upstream and downstream. Additionally, cameras and drones were used to analyze the process of the levee breach. Also, a new method using 3D point cloud for calculating the surface loss rate of the levee over time was suggested to evaluate the performance of the levee reinforcement method. It was compared to existing method based on image analysis and the result was reasonable. The proposed 3D point cloud methodology could be a solution for evaluating the performance of levee reinforcement methods.

• Clinical and Experimental Pediatrics
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• v.48 no.8
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• pp.846-856
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• 2005

Purpose : To measure the peak myocardial tissue velocities and patterns of longitudinal motion of atrioventricular(AV) annuli and assess body weight and heart rates-related changes in normal children. Methods : Using pulsed wave Tissue Doppler Imaging(TDI), we measured peak systolic, early and late diastolic myocardial velocities in 72 normal children at six different sites in apical-4 chamber (A4C) view and at four different sites in apical-2 chamber(A2C) view and compared those values with each other, also observing effects with body weights and heart rates. Longitudinal motions of the AV annuli were measured at three different sites in A4C. Results : There were no significant differences of the TDI parameters between gender, ECHO-machines and among the three Doctors performing TDI. Peak myocardial velocities were significantly higher at the base of the heart than in the mid-ventricular region and in the right lateral ventricular wall than in the left lateral ventricular wall or IVS. The TDI parameters showed no significant correlation with fractional shortening(%). Peak systolic and early diastolic myocardial velocities had no correlation with heart rates, but peak late diastolic velocities and A/E ratio correlated positively with heart rates. Correlations between the TDI parameters and body weight were inconsistent. Absolute longitudinal displacement and % displacement were not differ between gender and not correlated with the TDI parameters. Conclusion : We measured the peak myocardial velocities with TDI and the longitudinal motion of the AV annuli using M-mode echocardiography in normal children. With more large scale evaluation, we may establish reference values in normal children and broaden clinical applicabilities in congenital and acquired heart diseases.

• Clinical and Experimental Pediatrics
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• v.46 no.1
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• pp.67-75
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• 2003

Purpose : Intravascular stent implantation for the treatment of postoperative branch pulmonary artery(PA) stenosis has been used successfully. However, the cross sectional area of contralateral branch PA does not regress in spite of the successful dilation of the stenotic branch PA after stent implantation. We analyzed the morphologic and hemodynamic factors on the size of branch PA after successful stent implantation. Methods : The subjects in our study were 23 children who had undergone stent implantaion from Jan. 1995 to Jul. 2002 in the Division of Yonsei Pediatric Cardiology. We evaluated the cross sectional area index(CSAI) of branch PA before and after stent implantation at follow-up catheterization. We also investigated factors such as residual pulmonary stenosis, pulmonary regurgitation(PR), systolic pressure of right ventricle, and lung perfusion scan. Results : The CSAI of the RPA without stenosis changed from mean $238{\pm}17mm^2/BSA$ to mean $249{\pm}20mm^2/BSA$(P=0.47), but didn't regress. The CSAI of the LPA with stenosis was increased effectively by stent implantation from the mean $102{\pm}12mm^2/BSA$ to mean $125{\pm}11mm^2/BSA$(P< 0.05). At follow up after stent implantation, the CSAI of PA is correlated with the residual PR fraction after stent implantation. Conclusion : In a group with increased residual PR, CSAI of RPA was found to be significantly increased between the pre- and post-stages of stent implantation. So, we suspect that the pulmonary regurgitation remaining after right ventricle outlet tract(RVOT) dilatation surgery is correlated with the increase in CSAI of RPA.

• Journal of Chest Surgery
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• v.33 no.12
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• pp.941-947
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• 2000

Background: Central nervous system complication after coronary artery bypass grafting(CABG) is one of the major prognostic determinants and the use of the cardiopulmonary bypass(CPB) may increase the incidence of this devastating complication. In this study, the outcomes after off-pump CABG were studied and compared with those following the conventional CABG using CPB. Material and Method: Among the consecutive isolated CABG's performed in SNUH during Feb. 1995 and Jun. 1999, 338 coronary artery bypass grafting were divided into two groups. 223 patients underwent CABG using the CPB(Group I), and 115 patients underwent CABG without CPB(OPCAB)(Group II). All patients enrolled in this study received extensive preoperative examinations including thorough neurologic examination before and after surgery, transcranial doppler study, carotid duplex ultrasonography, and magnetic resonance angiography if necessary. Central nervous system(CNS) complications were defined as stroke, seizure, metabolic or hypoxic encephalopathy and transient delirium after surgery. Result: There were 61 cases(27.3%) who developed postoperative CNS complication in Group I, whereas 8 cases(7.0%) of CNS complications developed postoperatively in group II(p<0.05). Statistically significant predictors of postoperative CNS complications in group I were age and the use of cardiac assist devices perioperatively. Conclusion: This study suggested that omitting the use of CPB in CABG resulted in significant decrease of the postoperative CNS complications. OPCAB should be more widely applied especially to the elderly who have preexisting cerebrovascular disease.