• The Transactions of the Korean Institute of Electrical Engineers D
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• v.50 no.10
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• pp.494-501
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• 2001

In this study, the effects of vascular parameter changes and electrodes on VOP measurement based on IPG were simulated mathematically. For the evaluation of the effects of hemodynamic changes on VOP, a mathematical model, which consists of cardiovascular system model and venous occlusion model, was developed and the model solution representing the blood flow and pressure in measuring point was found by 2nd order Runge-Kutta method. And, with sensitivity coefficients obtained from finite element solution of electric field in measuring point, the effects of electrode system on measurement were evaluated. As increasing the resistance, the venous capacitance was not changed but the venous outflows were decreased and the decreased compliance reduced the venous capacitance. And, for several configurations of round electrodes and band electrodes, the sensitivity coefficients were computed using the electric field distribution along deep vein. In conclusion, the proposed mathematical cardiovascular model could be applied to the simulation study on the effects of hemodynamic parameters on DVT diagnosis with IPG. And, also the sensitivity coefficients could provide effective electrode configuration for exact measurement of VOP.

• Journal of Chest Surgery
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• v.36 no.8
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• pp.576-582
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• 2003

During the Off-Pump Coronary Arterial Bypass surgery (OPCAB), the manipulation of the heart can depress cardiac contractility and cause hemodynamic instability. In this study, hemodynamic parameters were measured during operation and the laboratory and clinical data were investigated to evaluate their effects on postoperative outcome. Material and Method: From March 2001 to August 2002, 50 consecutive patients who underwent OPCAB were included in this study. During the same period, total number of CABG was 71 The blood pressure, pulmonary artery pressure, mixed venous oxygen saturation, and cardiac index were measured before manipulation, after application of stabilizer, and at the end of anastomosis. Postoperatively, we measured the cardiac enzymes such as CK-MB, troponin 1 and checked the amount of inotropes required, chest tube drainage, the amount of transfusion, duration of ventilator support, and duration of ICU stay. Result: The number of mean distal anastomoses was 2.8$\pm$0.9 per patient. On elevation and stabilization of the heart, systolic blood pressure was depressed and pulmonary artery pressure was elevated significantly, but during each anastomosis no significant changes were detected. The peak level of cardiac markers was 29.2$\pm$46.7 for CK-MB, 0.69$\pm$0.86 for troponin 1 on postoperative day f. Among the intraoperative hemodynamic parameters, the ischemic change of EKG and bolus injection of inotropes significantly affected the posteroperative cardiac enzymes. But, no difference other than the level of cardiac enzymes between the two groups with or without the ischemic change of EKG and bolus injection of inotropes was noticed. Conclusion: The significant hemodynamic changes occurred when the heart was elevated and stabilized, however during anastomoses there were no significant changes. Serum cardiac enzymes rose significantly in the group that showed the ischemic charge of EKG or needed the bolus injection of inotropes for maintaining hemodynamic stability intraoperatively, but it did not affect the postoperative outcome. In conclusion, the ischemic change of EKG and the need for bolus injection of intropes during operation may be very indicative for probable ischemia.

• 순환기질환의공학회:학술대회논문집
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• 2002.11a
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• pp.35-35
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• 2002

• 대한핵의학회:학술대회논문집
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• 2005.11a
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• pp.316.1-316.1
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• 2005

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.10
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• pp.893-899
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• 2010

A previous study showed that hemodynamics is correlated with stenosis in the coronary artery. The flow characteristics and the distributions of the hemodynamic wall parameters in the coronary artery are investigated under physiological flow condition. The present study also aims to establish the mechanism of the generation of atherosclerosis by analyzing the hemodynamic variables in the coronary artery where atherosclerosis frequently occurs. The stenosis phenomena due to atherosclerosis are related to not only the biochemical reaction between blood and blood vessels but also the hemodynamic factors sush as flow separation and oscillatory wall shear stress. As the bifurcated angle increases, the size of the recirculation area that appears in the cross section increases and disturbed flow is observed in this area. We speculate that this area is the starting point of atherosclerosis in the coronary artery.

• Journal of Korean Neurosurgical Society
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• v.62 no.2
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• pp.183-192
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• 2019

Objective : The objective of this study was to analyze patient-specific blood flow in ruptured aneurysms using obtained non-Newtonian viscosity and to observe associated hemodynamic features and morphological effects. Methods : Five patients with acute subarachnoid hemorrhage caused by ruptured posterior communicating artery aneurysms were included in the study. Patients' blood samples were measured immediately after enrollment. Computational fluid dynamics (CFD) was conducted to evaluate viscosity distributions and wall shear stress (WSS) distributions using a patient-specific geometric model and shear-thinning viscosity properties. Results : Substantial viscosity change was found at the dome of the aneurysms studied when applying non-Newtonian blood viscosity measured at peak-systole and end-diastole. The maximal WSS of the non-Newtonian model on an aneurysm at peak-systole was approximately 16% lower compared to Newtonian fluid, and most of the hemodynamic features of Newtonian flow at the aneurysms were higher, except for minimal WSS value. However, the differences between the Newtonian and non-Newtonian flow were not statistically significant. Rupture point of an aneurysm showed low WSS regardless of Newtonian or non-Newtonian CFD analyses. Conclusion : By using measured non-Newtonian viscosity and geometry on patient-specific CFD analysis, morphologic differences in hemodynamic features, such as changes in whole blood viscosity and WSS, were observed. Therefore, measured non-Newtonian viscosity might be possibly useful to obtain patient-specific hemodynamic and morphologic result.

• Journal of Chest Surgery
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• v.21 no.1
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• pp.1-9
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• 1988

The left atrial [LA] dimension and atrial fibrillation [AF] in patients with mitral valvular heart diseases have been thought to be related to hemodynamic burden to the LA depending on severity of stenosis or regurgitation of mitral valve, left ventricular contractility and the heart conditions. If hemodynamic burden persists long, it can affect the LA wall and structural change of the LA wall itself can developed. So the structural change of the LA wall could be thought to be related to the LA dimension and AF. To verify this relation, the LA wall biopsy was performed in 26 patients with rheumatic mitral valvular heart disease at the left atriotomy incision margin which was posterior to the interatrial groove after completion of surgery to the mitral valve such as valve replacement or commissurotomy. Relation of the pathological state of the LA wall to AF and the LA dimension measured by M-mode echocardiography was studied. The conclusions were as follow. 1. There was tendency that degree of fibrosis of myocardium of the LA wall was related to the LA dimension. 2. There was more chance that patients who had severe fibrosis of myocardium of the LA wall had pre and postoperative AF. 3. There was no relation between reduction rate of the LA dimension before and after surgery and degree of fibrosis of myocardium of the LA wall.

• Journal of Acupuncture Research
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• v.21 no.5
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• pp.241-248
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• 2004

Objectives : The purpose of this study is to examine the hemodynamic characteristics of pulse point. Methods : The computational analysis algorithms of arterial tree system was derived. In order to investigate the effect of internal organ on the pulse point, the diameter of celiac artery was reduced by half. Results : The sensitivity of flow change at the Inyoung(Renying) is better than that of the Chongu(Cunkou). but the Inyoung was worse than the Chongu in the point of the left and right symmetry. The pressure changes at the Inyoung and the Chongu were in the similar range. Conclusions : It was found from the result that the Chongu shows the more symmetrical hemodynamic characteristics than the Inyoung.

• Journal of Chest Surgery
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• v.19 no.4
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• pp.578-583
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• 1986

Tetralogy of Fallot is the most common cyanotic congenital anomaly, which needs some operation for the survival. Perioperative mortality of the Tetralogy of Fallot was lowered remarkably in recent years, but some discussions were presented for the criteria of the corrective surgery and the corrective method of the pulmonary stenosis. In the Department of Thoracic and Cardiovascular Surgery of the Chunbug National University Hospital, 17 cases of tetralogy of Fallot were corrected totally from July in 1983 to August in 1984. In correction of the pulmonary stenosis, transannular patch was applied in B patients, infundibulectomy in 5, RVOT patch without transannular patch in 3, and isolated patches on RVOT and pulmonary trunk. Preoperative and early postoperative hemodynamic study revealed increased RA pressure in transannular patch group, which was significant statistically. [p<0.01]. Clinically, perioperative death occurred only in transannular patch group, and right heart failure signs including hepatomegaly, ascites, pleural effusion and peripheral edema were high in frequency in transannular patch group.

• YAKHAK HOEJI
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• v.40 no.4
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• pp.468-477
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• 1996

Vasopressin which is an antidiuretic hormone in human body produced the diuretic action in dog. This study was investigated in order to certify the diuretic action and to search out the mechanism of the action on the vasopressin. Vasopressin, when given in a dose of 10.0mU/kg, bolus+1.0mU/kg/min intravenously, exhibited the increase of urine flow(Vol), renal plasma flow(RPF), osmolar clearance (Cosm) and amounts of sodium and potassium excreted in urine ($E_{Na},\;E_K$), the decrease of reabsorption rate of sodium and potassium in renal tubules ($R_{Na},\;R_K$), and then elevated the mean arterial pressure(MAP). Vasopressin given in a increased dose to 30.0mU/kg, bolus+1.0mU/kg/min intravenously elicited the same aspect with that exhibited by a small dose in changes of Vol. and all renal function and potentiated the change rates, whereas this time MAP did not change at all when compared with control value. Vasopressin, when administered into a renal artery, did not induce the changes of Vol and all renal function in experimental (administered) kidney, but increased slightly the Vol, glomerular filtration rate(GFR), $E_{Na},\;and\;E_K$ expected the no change of $R_{Na}\;and\;R_K$ in the control (not administered) kidney. Vasopressin, when infused into carotid artery, showed the increase of Vol. GFR, $E_{Na},\;and\;E_K$ and no change of $R_{Na}\;and\;R_K$ in a dose of 1/5 of intravenous dose. Diuretic action of vasopressin administered into carotid artery was not influenced by renal denervation. Above results suggest that vasopressin produced diuretic action by hemodynamic changes in dogs. These hemodynamic changes may be mediated by central endogenous substances not associated with renal nerve.