45℃～60℃高温对活体猪肝脏损伤效果的实验研究

Experimental Study Evaluating The Temporal Evolution of Cell Damage Following 45 ℃-60 ℃ Temperature Elevation in Pig Liver in Vivo

目的探讨高温引起活体猪肝脏组织凝固坏死的最低有效温度及作用时间,为确定凝固性热疗参数提供实验数据。方法以多极射频为加热源,在活猪肝脏分别以45℃、50℃、55℃和60℃的温度持续作用15、30和60s,于实验结束即刻和3d后,在普通光镜及透射电镜下观察靶区肝脏组织细胞形态学变化。结果45℃温度作用15～60s,即刻观察,光镜下见肝细胞无明显变化;作用60s者3d后电镜下可见细胞器肿胀,但无破裂。50℃作用15s即刻光镜下可见肝细胞明显肿胀,电镜下见肝细胞空泡样变性、线粒体和内质网明显损害;3d后光镜下见出现肝细胞片状凝固性坏死。55℃持续作用15s即刻光镜下可见肝脏凝固性坏死。结论50℃持续作用15s可引起活体肝脏组织凝固性坏死,该温度与时间参数可作为凝固坏死热疗引起肝脏组织凝固性坏死的必要条件。

Objective To identify minimal effective temperature and time related to achieve coagulative necrosis in pig liver in vivo. The information is needed to determine optimal parameters of thermotherapy results in tissue necrosis within the target region but not decrease the risk of unintended damage to the surrounding tissue. Methods The livers of pigs were exposed in vivo to defined temperatures of 45 ℃ - 60 ℃ for varying durations of 15, 30, or 60 seconds using a radio-frequency ablation probe. Exposed tissue was obtained immediately after treatment or on day 3 following exposure. Histopathologic evaluation was performed by using light microscope, transmission electron microscope. Results Liver exposed to 45 ℃ for 15 - 60 seconds, demonstrated no discernable changes immediately following treatment on light microscope. Transmission electron microscopy performed on tissue exposed for 60 seconds by day 3 showed organelle swelling, but no rupture. At 50 ℃ for 15 seconds, light microscope immediately showed obvious cell swelling and electron microscope showed mitochondria membrane and endocytoplasmic reticulum breakdown. By day 3 there was evidence of coagulative necrosis on light microscope. Tissue exposed to 55 ℃ for 15 seconds demonstrated coagulative necrosis on light microscope performed on tissue obtained immediately following treatment. Conclusion A temperature elevation of 50 ℃ for 15 seconds can result in coagulative necrosis in liver in vivo. The information can be used to determine the necessary temperature elevation in liver to achieve coagulative necrosis using high intensity focused ultrasound.