Fabrication Of Elastic Aortic Models Using 3D Printing Technology

Objective:To establish an aortic elastic vascular model by using 3D printing technology,which can be used to assist patients with thoracic aortic aneurysm in endovascular treatment before operationMethods:1.Two groups of cylindrical models were made with paraffin.A group of silica gels with the same amount of hardener were coated with different layers on the surface of the model,and then the paraffin was dissolved at elevated temperature after the silica gel was dried.Finally,the cylindrical model was obtained..The elastic coefficient was calculated by measuring the change of the diameter of the model under pressure,and the optimum number of silicone coating layers was finally obtained.Another group chooses silica gel with different dosage of hardener,applies the best layer number,calculates the elastic coefficient with the same method,and obtains the relationship between the dosage of hardener and the elastic coefficient of the model.2.The patients underwent enhanced multi-slice spiral CT scanning of the aorta.After obtaining the data,they were reconstructed and sliced by using Mimics 17.0 and Cura15.0 software.The data were transferred to a 3D printer.The model of aortic aneurysm was printed by melt deposition using acrylonitrile butadiene styrene(ABS)as material.3.Measure the patient's basic blood pressure,and measure the diameter of aortic arch during a cardiac cycle with echo tracking technology.Calculate the elasticity coefficient of the artery and enter the formula to get the best ratio of silica gel and hardener.4.According to the appropriate proportion of hardener,silica gel was evenly applied on the surface of 3D model.After silica gel was dried,ABS plastics were dissolved with acetone to obtain an elastic hollow vascular model.Result:1.a.After two layers of elastic material were applied,the elasticity of the model was the closest to the true vascular elasticity.;b.For each group of models with different dosage of hardener,the change of pressure and diameter is in line with the linear relationship(r2?1).The relationship between hardener dosage X(1.2<X<2.8)and elastic coefficient K satisfies the cubic equation(r2=0.990),and the formula is K=-3.243X~2+2.057X~3+16.587;c.In this study,the preoperative arterial pressure difference was 61 mmHg,the diameter of aortic arch changed to 2.96,the K value was20.608,and the dosage of sclerosing agent was 100:2;2.Guidance surgery:According to the preoperative evaluation results,the final choice of occluding part of the left subclavian artery for peritoneal stent release,to avoid the window may affect the physical properties of the covered stent.After stent release,angiography showed that the aneurysms were isolated successfully.There was no significant leakage in the proximal end of the aneurysms.The left subclavian artery developed well.The muscle strength of the left upper limb was normal.The blood pressure difference between the two upper limbs was less than 10 mmHg.No neurological complications occurred.The patient was discharged smoothly 5 days after operation.Conclusion:1.The 3D model can visualize complex lesions and guide doctors to choose the appropriate operation plan and stent size to reduce the exposure of radiation and to improve the success rate of the operation.It also helps to train young doctors and help doctors communicate effectively with patients.2.Silica gel has good strength and elasticity,its chemical property is not active,the elastic coefficient can be changed by adding different proportion of hardener,which is helpful to make the elasticity of model more close to the true vascular elasticity by adjusting the dosage of hardener.Is an ideal material for making arterial models.3.Compared with the rigid model,the elastic model has the advantage of simulating the vascular morphological change after the stent release,and for some complex aneurysms,the rigid model may not be able to simulate the entry of the conveyer,but the elastic model can pass through normally.