| Background: The catheter-based renal denervation(RDN)can regulate autonomic nervous imbalance and thus lower blood pressure(BP)by intervention.RDN is a research hotspot in recent years as an alternative for patients with resistant hypertension(RHT).However,the efficacy of RDN remains controversial due to the inconsistent results in postoperative BP reduction,which has limit the clinical application of RDN.The causes of these phenomena remains unexplored.Previous studies have shown that applying electrical stimulation inner renal artery can induce BP responses with diverse trends.Selective RDN guided by strong elevated BP response has a superior hypotensive effect,and the magnitude of BP increase during stimulation is closely related to that of the postoperative BP decrease.These results suggest that the dominate BP-regulative function of the site with BP elevate to stimulation is pressor.Electrical stimulation makes a potential method for distinguishing the BP-regulative function of the site,guiding RDN and indicating prognosis.Therefore,it is reasonable to speculate that depressor is the dominate BP-regulative function of the site with BP decline to stimulation,at which ablated may weaken,offset of even be harmful to the overall hypotensive effect brought about be the BP-elevation site ablation.resulting in further imbalance in autonomic nerve system,which should be avoided during RDN.However,the systemic effect of ablation at sites with BP-decline have been a blank-leaving.Previous methodological study revealed that when the frequency is less than 8 Hz,the BP changes to stimulation is positively correlated with the frequency output,and when the frequency is higher than the threshold of 8-12 Hz,the BP pattern generated with stimulation tended to be consistent.As a potential method for guiding RDN and prompting prognosis,clarifying the optimal output parameters of renal stimulation can provide more accurate and feasible reference for interventionalists.In addition to the rough increase or decrease trend,the BP changes to stimulation present a variety of specific change patterns,and for the other vital parameter of electrical energy output,the effect of different current intensity on the BP response to stimulation has not been explored.Objective: To compare the effect of selective ablation guided by decline/elevation response to electrical stimulation on BP and systemic sympathetic activity.To explore the correlation between the output current intensity of stimulation and induced BP changes.and provide animal experimental evidence for electrical stimulation as an immediate BP-regulative functional indicator for guiding RDN and enhancing the therapeutic effect.Methods:The study was divided into 2 parts:Part 1: 24 Kunming dogs were enrolled and randomly allocated to BP-decline sites ablation group(DSA),BP-elevation sites ablation group(ESA)or renal sitmulation control group(RSC).The effects of selective ablation guided by 2 inverse stimulation-induced BP responses(decline and elevation)on 4-week BP and plasma norepinephrine(NE)were compared.Part 2: 13 Kunming dogs were included,and 18 available renal arteries were randomly assigned to four current parameters stimulation group(FOS,n=18),three current parameters stimulation group(THS,n=4)and two current parameters stimulation group(TWS,n=4).The differences on BP changes-induced by the stimulation with current parameters of 5,10,15,20 m A were compared.Results:Part 1: Ablation at BP-decline sites can lead to significant increases in BP and plasma NE after 4 weeks(P=0.016;P=0.033),while BP-elevation sites ablation can simultaneously produce superior reduction in 4-week BP and plasma NE(P=0.002;P=0.008).Moreover,the stimulation-induced maximum systolic blood pressure(SBP)changes were negative correlated the changes of SBP and plasma NE at 4 weeks(R=-0.708,P=0.002;R=-0.754,P=0.001).A correlation was observed between the SBP and plasma NE changes at 4 weeks(R=0.724,P=0.002).Part 2: A significant difference was found in the types of BP change patterns to electrical stimulation with current output of 5m A and 10 m A(P< 0.001),but there were no notable differences in the maximum SBP changes of the sites with BP-elevation or BP-decline trend(P=0.061;P=0.398).The types of BP change patterns to stimulation with current output of 10 m A and 15 m A was significant different(P < 0.001),but no remarkable difference was observed in the maximum SBP changes of the sites with BP-elevation or BP-decline trend(P=0.113;P=0.158).There were no significant difference between the stimulation with current output of 15 m A and 20 m A in the types of BP change patterns or the maximum SBP changes of the sites with BP-elevation or BP-decline trend(P>0.05 for all).Conclusions: Ablation at sites with BP-decline responses to stimulation is detrimental to antihypertensive treatment and should be avoid in RDN.With the current output of 15 m A,renal stimulation can induce a trend-exact BP change for identifying dominant BP-regulation function of the site and help to improve the therapeutic efficacy of RDN. |
