肾去交感神经对犬心房颤动易患性和心房重构的影响

目的 探讨肾去交感神经对犬长期快速右心房起搏后心房颤动（房颤）易患性和心房重构的影响.方法 20只杂种犬分为假手术组、右心房起搏（RAP）组、肾去交感神经（RSD）组3组.假手术组（n=6）植入起搏器后程控关闭起搏器;RSD组（n=7）先行双侧肾交感神经消融,经6周恢复后植入起搏器;RAP组（n=7）和RSD组快速起搏（400～ 450次/min）右心房5周.所有犬在实验基线期和终点进行超声心动图及电生理检查,取静脉血检测血管紧张素Ⅱ（AngⅡ）水平;处死动物后迅速取心房组织行形态学评估.结果 与假手术组和RSD组相比,RAP组犬起搏5周后房颤诱发率明显升高（P＜0.05）.RAP组心房有效不应期（AERP）明显缩短（142±8）ms对（115±9）ms,P＜0.05],而RSD组AERP缩短无统计学意义（P＞0.05）.超声心动图结果发现,RAP组和RSD组的左心房内径（LAD）、左心室舒张末期内径（LVEDD）、左心房容积最大值和最小值（LAVmax和LAVmin）起搏5周后均较起搏前明显增加,但RSD组的LAVmax和LAVmin较RAP组明显减少（P＜0.05）.右心房快速起搏5周后,与假手术组相比,RAP组和RSD组犬血清AngⅡ水平明显增加RAP组：（217.5±53.5） ng/L对（95.0±25.2） ng/L,P＜0.05;RSD组：（149.6±26.3）ng/L对（95.0±25.2） ng/L,P＜0.05];与RAP组相比,RSD组犬血清AngⅡ显著降低（（149.6±26.3）ng/L对（217.5±53.5） ng/L,P＜0.05）.电镜结果显示肾去交感神经能显著减缓快速右心房起搏5周后导致的肌丝分解、肌纤维带型和收缩完整结构的丧失和线粒体肿胀等超微结果变化.Masson三色法染色结果表明与RAP组相比,RSD组犬左、右心房肌的胶原容积分数（CVF）均明显减低（P＜0.05）.结论 肾去交感神经可抑制长期快速右心房起搏后房颤的诱发和心房重构.

Effect of renal sympathetic denervation on the inducibility of atrial fibrillation and atrial remodeling in ambulatory canines of prolonged atrial pacing

Objective To investigate the effect of renal sympathetic denervation on the inducibility of atrial fibrillation （AF） and atrial structure remodeling after prolonged atrial pacing in ambulatory canines.Methods Twenty mongrel dogs were implanted with a high frequency cardiac pacemaker inserting a transvenous lead at the right atrial appendage,and were divided into three groups：sham-operated group （n =6）,RAP group （n =7） and RSD group （n =7）.Sham-operated group dogs were only implanted with pacemakers without pacing.In RSD group dogs,a pacemaker was implanted 6 weeks after RSD was performed bilaterally for recovery.Atrial pacing was maintained for 5 weeks in both RAP group and RSD group.Echocardiography and electrophysiological indexes,such as AERP and the inducibility of AF,were measured in all the animals at the baseline and endpoint of the protocol.Results AF was induced easily in the RAP group than in the shamoperated group and RSD group after 5 weeks atrial pacing （P〈0.05）.AERP was significantly shortened after prolonged atrial pacing in RAP group （142± 8）ms vs.（115 ±9）ms,P〈0.05] ;however,the decreasing trend of AERP in RSD group was not significantly different （P 〉 0.05）.Echocardiography showed left atrial volume （LAVmax and LAVmin） was significantly reduced in RSD group than in RAP group （P〈0.05）,although LAD,LVEDD,LAVmax and LAVmin were significantly increased by atrial pacing for 5 weeks compared with values observed before atrial pacing both in RAP group and RSD group.The plasma level of Angiotensin Ⅱ was significantly increased in both RAP group and RSD group compared with sham-operated group after 5 weeks atrial pacingRAP group：（217.5 ± 53.5） ng/L vs.（95.0±25.2）ng/L,P〈0.05 ; RSD group：（149.0±26.3） ng/L vs.（95.0±25.2） ng/L,P〈0.05）],but the increasing trend was inhibited in RSD group compared with RAP group （149.6±26.3）ng/L vs.（217.5±53.5）ng/L,P〈0.05].Ultrastructural changes by transmission electron microscopy that severe disintegration of myofilaments,loss of banding pattern and integrity of contractile elements,and mitochondrial swelling with a decrease in the density observed after 5 weeks atrial pacing were markedly attenuated by RSD.Atrial myocardium stained with Masson＆#39; s trichrome showed that extensive fibrosis was especially visible in RAP group dogs,but attenuated in the RSD group dogs.Conclusion Catheter-based renal denervation can reduce the incidences of AF and suppress atrial remodelling by prolonged RAP.