交变磁场诱导冠状动脉支架的升温

背景：对于药物涂层支架的安全性问题目前尚存在争议。磁诱导热疗可以利用交变磁场诱导磁介质升温，对局部病灶进行热疗。由于心脏支架多以不锈钢、镍、铬等合金材料构成，因此具备在磁场下的升温条件，并且目前国内外尚无通过磁诱导心脏支架升温的相关报道。目的：观察不同冠状动脉支架在交变磁场下的升温情况。探讨磁场强度、磁场频率、磁场方向及支架的材质对冠状动脉支架升温的影响规律。方法：将不同材质冠状动脉支架(316L型、镍钛合金、钴铬合金)置于交变磁场中，调节磁场参数(场强、频率)和支架长轴与磁场方向的夹角，观察上述因素对交变磁场诱导冠状动脉支架升温的影响。结果与结论：支架材料对磁场诱导升温有显著影响，并以316L型支架升温效果最好；随着支架长轴与磁场方向所成角度的增大，升温效果明显降低；随着交变磁场频率及电流强度增加温度升高更明显。

Coronary artery stent heating under alternating current magnetic field

BACKGROUND: The safety of drug eluting stent is still in dispute. Local heating can be performed by exposing magnetic medium to alternating current (AC) magnetic field. The stents are mainly composed of alloy, so it is possible to heat under magnetic field, but few reports have been obtained in China or abroad. OBJECTIVE: To study the temperature increasing of coronary stent under the AC magnetic field, and to explore the effects of magnetic field parameters (frequency and current intensity), as well as stent materials on the temperature increasing.METHODS: Coronary stents of different materials: 316L stainless steel, Ni-Ti alloy and Co-Cr alloy were placed in the AC magnetic field. Temperature increasing induced by the AC magnetic field of various process parameters (frequency and current intensity, angle between the stent axis and the field direction) was examined by Cu-CuTi thermo-couple.RESULTS AND CONCLUSION: Stent materials had great effect on the temperature increasing induced by magnetic field, among which 316L stainless steel had the highest heating effect. Temperature increasing would be restricted with increasing of the angle between the stent axis and the field direction. Higher temperature increasing was observed at higher AC magnetic frequency and current intensity.