• International Journal of Vascular Biomedical Engineering
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• v.1 no.2
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• pp.20-29
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• 2003

A new treatment for coronary artery occlusive disease is being developed in which a shunt or conduit is placed directly connecting the left ventricle with the diseased artery at a point distal to the obstruction. To aid in assessing and optimizing its benefit, a computational model of the cardiovascular system was developed and used to explore various design conditions. Simulation results indicate that in complete LAD occlusion, flow can be returned to approximately 65% of normal if the conduit resistance is equal for forward and reverse flow, increasing to 80% in the limit in which backflow resistance is infinite. Increases in flow rate produced by asymmetric flow resistance are considerably enhanced in the case of a partial LAD obstruction since the primary effect of resistance asymmetry is to prevent leakage back into the ventricle("steal") during diastole. Increased arterial compliance has little effect on net flow with a symmetric shunt, but leads to considerable augmentation when the resistance is asymmetric. These results suggest that an LV-LAD conduit will be beneficial when stenosis resistance(Rst) > 27 PRU if resistance is symmetric.

• Proceedings of the KOSOMBE Conference
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• v.1992 no.11
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• pp.43-46
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• 1992

$\underline{In\;vitro}$ velocity measurements were made using both the pulsed Doppler ultrasound (PDU) machine and laser Doppler anemometer (LDA) system in order to investigate the flow characteristics near the aortic bifurcation. Velocities measured from the PDU machine was in good agreement with those from the LDA. The flow in the daughter branches was three-dimensional with a secondary flow. The oscillating wall shear stress with this secondary fluid motion is well correlated with the localization of the atherosclerosis.

• Journal of Institute of Control, Robotics and Systems
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• v.4 no.3
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• pp.315-320
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• 1998

In this paper, we present the PID control method for the controlling flow rate of highly complicated nonlinear Left Ventricular Assist Device(LVAD) with pneumatically driven mock circulatory system. Beat Rate (BR), Systole-Diastole Rate (SDR) and flow rate are used as the main variables of the LVAD system. System modeling is completed using the neural network with input variables (BR, SDR, their derivatives, actual flow) and an output valiable(actual flow). Then, as the basis of this model, we perform the simulation of PID control to predict the performance and tendency of the system and control the flow rate of LVAD system using the PID controller. The ability and effectiveness of identifying and controlling a LVAD system using the proposed algorithm will be demonstrated through computer simulation and experiments.

• 한국가시화정보학회:학술대회논문집
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• 2006.12a
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• pp.121-124
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• 2006

The arteries are very important in cardiovascular system and easily adapt to varying flow and pressure conditions by enlarging or shrinking to meet the given hemodynamic demands. The blood flow in arteries is dominated by unsteady flow phenomena due to heart beating. In certain circumstances, however, unusual hemodynamic conditions cause an abnormal biological response and often induce circulatory diseases such as atherosclerosis, thrombosis and inflammation. Therefore quantitative analysis of the unsteady pulsatile flow characteristics in the arterial blood vessels plays important roles in diagnosing these circulatory diseases. In order to verify the hemodynamic characteristics, in-vivo measurements of blood flow inside the extraembryonic arterial bifurcation cascade of chicken embryo were carried out using a micro-PIV technique. To analyze the unsteady pulsatile flow temporally, the (low images of RBCs were obtained using a high-speed CMOS camera at 250fps with a spatial resolution of $30{\mu}m\times30{\mu}m$ in the whole blood vessels. In this study, the unusual flow conditions such as flow separation or secondary flow were not observed in the arterial bifurcations. However, the vorticity has large values in the inner side of curvature of vessels. In addition, the mean velocity in the arterial blood vessel was decreased and pulsating frequency obtained by FFT analysis of velocity data extracted in front of the each bifurcation was also decreased as the bifurcation cascaded.

• Journal of Chest Surgery
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• v.44 no.6
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• pp.423-426
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• 2011

We report on two women who underwent myocardial revascularization associated with antiphospholipid syndrome (APS) with different pathogenic patterns. The first woman presented with acute myocardial infarction, and preoperative angiograms demonstrated rapidly progressing coronary lesions, presumptive unstable plaque, and dissection. Operative findings, however, showed fresh thrombi in the coronary arteries, and she was diagnosed postoperatively as having APS. Her one-year angiogram demonstrated improved coronary lesions and a competitive flow pattern in the grafts. The second woman presented with unstable angina and had been treated for systemic lupus erythematosus and secondary APS for more than 14 years. She underwent myocardial revascularization due to accelerated coronary atherosclerosis. Her one-year angiogram demonstrated patent grafts.

• Advances in biomechanics and applications
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• v.1 no.4
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• pp.279-292
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• 2014

This paper presents some simulations of fluxes and pressures in the coronary network, in the case of very severe coronary disease (several stenoses on the left branches and total occlusion of the right coronary artery). In that case, coronary artery bypass graft surgery is the commonly performed procedure. However, the success of the intervention depends on many factors. Modeling of the coronary circulation is thus important since it can help to understand the influence of all these factors on the coronary haemodynamics. We previously developed an analog electrical model that includes the eventual presence of collateral flows, and can describe the different revascularization strategies (two grafts, three grafts, ...). The aim of the present work is to introduce in our simulations the time-dependence of the coronary microvascular resistances, in order to better represent the effect of the systolic ventricular contraction (which induces an elevation of the resistances because the vessels are squeezed).

• Journal of Chest Surgery
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• v.39 no.11 s.268
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• pp.850-853
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• 2006

The VSD in TOF is usually large and unrestrictive with an equal to or greater than that of the aortic annulus. Typically shunting through the VSD is bidirectional or right-to-left component. Restrictive VSD in TOF caused by ingrowing fibrotic tissue is very rare. We report a case of restrictive VSD and LVOTO in TOF caused by ingrowing fibrotic tissue with the review of literature.

• Journal of Chest Surgery
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• v.28 no.1
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• pp.73-77
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• 1995

We are reporting one case of right subclavian vein thrombotic occlusion as a result of previous hemodialysis catheter placement in a patient with a functioning right brachio-cephalic arteriovenous fistula. Its complication was painful right arm swelling, limitation of motion and cellulitis. Diagnosis was confirmed by right subclavian venography and the complication was successfully managed by right subclavian vein-superior vena cava bypass with a GoreTex vascular graft. The arteriovenous fistula had remained to protect patency of the bypass at first, but two months later after the operation, the arteriovenous fistula had to be occluded because of the heart failure resulting from shunt over flow. After ligation of arteriovenous fistula, heart failure improved, and uncomfortable arm swelling did not develop again.

• Journal of Ginseng Research
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• v.46 no.3
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• pp.321-330
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• 2022

Coronavirus has been spreading rapidly around the world since it broke out in China in 2019. Respiratory diseases caused by coronavirus infection cause various diseases ranging from asymptomatic subclinical infections to severe pneumonia and cardiovascular complications, leading to death. In this regard, natural products are being studied to prevent various diseases caused by COVID-19. In current review, we would like to present mechanisms related to the inhibition of heart disease in ginseng and ginsenoside against SARS-CoV-2. In many previous studies, ginseng and ginsenoside are known to have antioxidant, blood flow improvement, improvement of vascular and heart function, blood pressure control, suppression of myocardial infarction and heart failure, and antiarrhythmia. Therefore, ginseng and ginsenoside have a possibility to suppress cardiovascular complications caused by COVID-19. Many of research provide evidence for ginseng and ginsenoside as treatments for the risk of cardiovascular complications. However, in this review, more specific contents on the proposition of the efficacy of ginseng and ginsenoside for COVID-19 should be presented. Therefore, we hope that researches to reduce cardiovascular complications of ginseng and ginsenoside for COVID-19 should be presented to reduce mortality for COVID-19.

• Journal of Chest Surgery
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• v.55 no.5
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• pp.413-416
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• 2022

A 32-year-old woman diagnosed with Turner syndrome presented to the hospital for an evaluation of cardiovascular complications. Preoperative computed tomography (CT) and echocardiography showed progression of aortic root and ascending aorta dilatation, as well as a bicuspid aortic valve. There was no evidence of aortic regurgitation. We planned valve-sparing aortic root replacement and ascending aorta replacement with a high risk of aortic rupture. Intraoperatively, we incidentally found a juxtacommissural origin of the right coronary artery (RCA). We performed aortic valve reimplantation using a graft designed with a key-shaped hole to wrap the juxtacommissural-origin RCA by modifying the Florida sleeve technique. Coronary blood flow was patent on postoperative CT angiography, and there was no evidence of aortic regurgitation on postoperative echocardiography. The patient was discharged from the hospital on postoperative day 7 without any complications.