Effects of Coronary Artery Lesion Characteristics on Myocardial Ischemia / 医用生物力学

Objective To investigated the effect of stenosis characteristics (vascular elasticity and plaque properties) on myocardial ischemia. Methods An ideal geometric multi-scale coronary stenosis model based on fluid-structure interaction was established, and the fractional flow reserve (FFR) was simulated to evaluate myocardial ischemia. The effects of vascular elastic wall (elastic modulus of 1 MPa) and rigid wall, plaque types (lipid-rich plaque and calcified plaque) and plaque volume on myocardial ischemia were considered separately. Results The FFRCT simulation result of vessels with elastic wall was larger than that with rigid wall under all stenosis situations. The FFRCT of vessels in lipid-rich lesions was higher than that of calcified plaque (P=0.001). The trapezoidal plaque volume was larger than the cosine plaque volume, and the FFRCT of vessels in trapezoidal plaque was smaller than that of cosine plaque (P=0.001). Conclusions Vascular elasticity is a critical factor to simulate vascular hemodynamics. In moderate stenosis, calcified plaques are more likely to induce myocardial ischemia due to the larger luminal deformation and dilation of rich lipid plaque. When the stenosis is constant, the smaller the plaque volume, the higher the FFRCT and the smaller the possibility of myocardial ischemia.

Application of hemodynamic optimization in the design of artificial heart / 生物医学工程学杂志

Heart failure is one kind of cardiovascular disease with high risk and high incidence. As an effective treatment of heart failure, artificial heart is gradually used in clinical treatment. Blood compatibility is an important parameter or index of artificial heart, and how to evaluate it through hemodynamic design and

Progress of basod on hemodynamics simulation cardiovascular Surgical planning / 医用生物力学

Hemodynamics-simulation-based cardiovascular surgical planning.which is the patient-specific surgical hemodynamics optimization based on medical image,is the further development of clinical-applica-tion-oriented computational hemodynamics,it is very helpful for cardiovascular surgical decision-making.The art-in-work of hemodynamics-simulation-based cardiovascular surgical planning in both domestic and over-seas research was reviewed,the key problems and solutions involved were analyzed,and the further develo-ping objectives were presented.

Influences of graft diameter on the blood flow in 2-way bypassing surgery / 生物医学工程学杂志

The graft diameter plays a critically important role in the long-term patency rates of bypass surgery. To clarify the influence of graft diameter on the blood flows in the femoral 2-way bypass surgery, the physiologically pulsatile flows in two femoral bypass models were simulated with numerical methods. For the sake of comparison, the models were constructed with identical geometry parameters except the different diameters of grafts. Two models with small and large grafts were studied. The boundary conditions for the simulation of blood flow were constant for both models. The maximum Reynolds number was 832.8, and the Womersley number was 6.14. The emphases of results were on the analysis of flow fields in the vicinity of the distal anastomosis. The temporal-spatial distributions of velocity vectors, pressure drop between the proximal and distal toe, wall shear stresses, wall shear stress gradients and oscillating shear index were compared. The present study indicated that femoral artery bypassed with a large graft demonstrated disturbed axial flow and secondary flow at the distal anastomosis while the axial flow at its downstream of toe was featured with larger and more uniform longitudinal velocities. Meanwhile, the large model exhibits less refluences, relatively uniform wall shear stresses, lower pressure and smaller wall shear stress gradients, whereas it does not have any advantages in the distributions of secondary flow and the oscillating shear index. In general, the large model exhibits better and more uniform hemodynamic phenomena near the vessel wall and may be effective in preventing the initiation and development of postoperative intimal hyperplasia and restenosis.

Simulation of stent treatment for aneurysms in the inner bend of aortic arch / 生物医学工程学杂志

Endovascular stent is a new technique for the treatment of aortic arch aneurysms. The present simulation study of endovascular stent treatment for aneurysms in the inner bend of aortic arch is initiated by the fact that no one has ever investigated the hemodynamics of stented aortic arch aneurysm harboring a bleb. For the comparative convenience, a stented and a nonstented aortic arch aneurysm models were constructed respectively. Physiological blood flows in both models were simulated using the computational fluid dynamics method. The detailed flow patterns, pressure and wall shear stress distributions around the aneurysm of both models were compared and analyzed so as to evaluate the effectiveness of endovascular stent treatment for aortic arch aneurysms. Results showed that the stented model is attributed to substantially different intra-aneurysmal flow patterns versus the nonstented model. Flow activities within the stented aneurysmal sacs are markedly diminished, specifically the pressure and wall shear stress in the bleb were significantly decreased. These phenomena allow us to conclude that endovascular stent can promote intra-aneurysmal thrombus development and attenuating aneurysm rupture risk.

Thermal Problems and Methods in Invasive Microwave Coagulation Therapy / 대한의료정보학회지

OBJECTIVE: To study some thermal problems in invasive microwave coagulation (IMC) therapy. METHODS: Temperature fields predicts, limitation and remedy methods of the Pennes bioheat transfer equation during the temperature distribution analyses and how to kill a large anomalistic tumor for only once were discussed. RESULTS: The coagulation area between the simulations and actual measured results showed good correspondence. Blood flow influenced the rise in temperature significantly. CONCLUSIONS: Thermal distribution with computer simulation in invasive microwave coagulation therapy is an accurate and reliable method.