犬下腔静脉脂肪垫对心脏电生理功能的影响

Physiological functional characterization and clinical implication of inferior vein cava fat pad

目的研究心外膜下腔静脉脂肪垫(IVCFP)的生理功能特点,探讨其对房颤时快速心室率控制的临床意义。方法采用高频电流刺激和射频消融的方法,观察刺激或消融IVCFP前后窦房结和房室传导功能的变化;采用S1S1程序刺激诱发房颤,观察刺激IVCFP对诱发房颤时心室率的影响。结果完成试验犬12只,刺激或消融IVCFP前后,窦房结恢复时间(SNRT)及校正窦房结恢复时间(SNRTc)均没有变化;但是刺激IVCFP可使房室传导功能降低,A-H间期较刺激前明显延长(122±12 m svs82±10 m s,P<0.05);消融脂肪垫后,迷走神经所介导的负性房室传导作用完全消失。诱发房颤时,刺激IVCFP可以使诱发房颤的平均心室率降低。结论IVCFP可选择性地支配房室结,而不影响窦房结功能。IVCFP刺激可能为房颤时快速心室率的控制提供一种新的治疗方法。

AIM To investigate the physiological functional characterization of the inferior vena cava fat pad and to discuss the potential application of the fat pad to parasympathetic mediated ventricular rate control during atrial fibrillation. METHODS With high-frequency electrical stimulation and radio-frequency ablation methods, the functions of SAN and atrioventricular conduction were valuated when the fat pad was stimulated or after ablation. With electrical stimulation on the fat pad, the average ventricular rate was measured during induced fibrillation. RESULTS The experiment was completed in 12 dogs. There was no significant difference of SNRT or SNRTc compared with baseline when the fat pad was stimulated with high-frequency electrical stimulation or ablated with radiofrequency energy. AH interval was found prolonged compared with baseline （ 122.2 ± 12.4 ms vs 82.5 ± 10.3 ms ,P 〈0.05 ） when the fat pad was stimulated. Atrioventricular conduction became further prolonged with the increase of the frequency of electrical stimulation on fat pad. The stimulation took effect in 2 seconds and normal atrioventricular conduction resumed in 3 seconds after the stimulation ceased. After the ablation of the inferior vena cava fat pad, no parasympathetic mediated negative dromotropic response was found except negative chronotropic response. During the induced atrial fibrillation, the average ventricular rate decreased when the stimulation was applied to the fat pad. CONCLUSION IVCFP can selectively control AVN. Ablation of IVCFP results in parasympathetic denervation on AVN totally. We presume that IVCFP can be developed into a novel method to control the rapid ventricular rate during atrial fibrillation.