Abstract: Objective:To investigate the changes of the serum indexes of renin-angiotensin-aldosterone system(RAAS) and atrial fibrillation burden in the atrial fibrillation model dogs underwent spinal cord stimulation(SCS) therapy, and to illuminate the therapeutic effect of SCS on the atrial fibrillation and its effect on RAAS. Methods:A total of 24 healthy adult dogs were chosen.The pacemakers and miniaturized insertable cardiac monitors were implanted into 16 dogs to establish the atrial fibrillation models by rapid right atrial pacing. Then 16 model dogs were divided into atrial fibrillation (AF) group and SCS group(n=8). The spinal cord stimulators were implanted into the dogs in SCS group to release stimulation for 12 weeks. And the rest dogs were regareded as blank control group(n=8). The atrial fibrillation burden of dogs in AF group and SCS group was monitored by miniaturized insertable cardiac monitors;the left and right atrial areas of dogs in three groups were measured by echocardiography;the serum levels of renin, angiotensin Ⅱ(Ang Ⅱ), aldosterone(ALD), angiotensin Ⅱ type 1 receptor(AT1R), angiotensin Ⅱ type 2 receptor(AT2R) and angiotensin converting enzyme 2(ACE2) of the dogs in three groups were detected by ELISA method. Results:Compared with AF group,the atrial fibrillation burden of the dogs in SCS group was decresed obviously (P<0.05).The left and right atrial areas of dogs in AF group were larger than those in blank control group(P<0.05);the left atrial area of the dogs in SCS group was smaller than that in AF group (P<0.05),the right atrial area was also smaller,but there was no significant difference (P>0.05);the left and right atrial areas of the dogs in SCS group were larger than those in blank control group (P<0.05).The serum ACE2 level of dogs in AF group was lower than that in blank control group (P<0.05)and the levels of serum renin, Ang Ⅱ, ALD, AT1R and AT2R of the dogs in AF group were all higher than those in blank control group(P<0.05);the serum ACE2 level of the dogs in SCS group was higher than that in AF group(P<0.05)and the levels of serum renin, Ang Ⅱ, ALD, AT1R, and AT2R of the dogs in SCS group were all lower than those in AF group(P<0.05).Compared with before modeling,the serum ACE2 level of dogs in AF group after modeling was decresed(P<0.05),and the levels of serum renin, Ang Ⅱ, ALD, AT1R, and AT2R were incresed(P<0.05); compared with before treatment,the serum ACE2 level of the dogs in SCS group after treatment was incresed (P<0.05), and the levels of serum renin, Ang Ⅱ, ALD, AT1R, and AT2R were decresed (P<0.05). Conclusion:Atrial fibrillation can activate the RAAS. SCS therapy can suppress the atrial fibrillation and it can suppress RAAS activated by atrial fibrillation,so SCS can restraint the deterioration of atrial fibrillation.The serum RAAS indexes are so important observation indexes to evaluate the outcome of SCS in the treatment of atrial fibrillation.

Key words: atrial fibrillation, spinal cord stimulation, dog, renin-angiotensin-aldosterone system