Analysis Of Autonomic Nerve Function In Patients With Vasovagal Syncope During Head-up Tilt Test

Objective:Through the quantitative measurement and comparison of heart rate variability and deceleration apacity of rate in different stages of head-up tilt test in patients with vasovagal syncope,the role of abnormal autonomic changes in the occurrence of vasovagal syncope was further analyzed..Methods:The head-up tilt tsting(HUTT)of patients with highly suspected Vasovagal syncope(VVS)in the outpatient and inpatient treatments of the First Affiliated Hospital of Kunming Medical University from October 2017 to December 2020 was collected.There were 134 patients with vasovagal syncope who were positive in the drug test phase.Take the 4-minute continuous ECG in each stage of the HUTT according to the predetermined time setting,and record them as the basic lying position time period,the basic upright position time period,the time period before the positive lying position,and the time period after restoring the supine position.and at time before positive reset 4 minutes,before positive reset 2 minutes,before positive reset 30 seconds,the time of positive reset,and 2 minutes after positive reset,the 30-second ECG of the Head-up tilt test was intercepted and recorded as T-2,T-1,T0,T1,T2,and analyzed separately Low frequency power(LF),high frequency power(HF)and low frequency power/high frequency power(LF/HF)in the frequency domain index of heart rate variability,where low frequency power(LF)reflects sympathetic nerve activity and part vagus nerve activity,high frequency power(HF)reflects vagus nerve activity,low frequency power/high frequency power(LF/HF)reflects sympathetic nerve activity,and analyzes the heart rate variability(HRV)time domain indicators and Frequency domain indicators and heart rate deceleration force Deceleration capacity of rate(DC).Results:The average age of 134 patients with positive HUTT was 33.18±19.01 years old,43 patients were younger than 18 years old(32.09%of the total number)and older than 65 years old accounted for 6.7%;73.10%of the 134 patients were women.Among them,77 cases were mixed(MX),52 cases were Vasodepressor(VD),and 5 cases were Cardioinhibitory(CI).Compared with patients with vasovagal syncope,it was found that the period of LF before positive reduction was significantly lower than the other three periods(P<0.01);the period of HF in the basic upright position was lower than that in the basic supine position(P<0.01),The time period before positive reduction was lower than the basic supine position time period and the basic upright position time period(P<0.01);LF/HF increased in the basic upright position time period compared with the basic supine position time period(P<0.01).The time period before positive reduction was higher than that of the basic supine position and the basic upright position(P<0.01).Before and after the positive reset,it was found that LF was the lowest 2 minutes before the positive reset,then gradually increased,the highest at the time of the positive reset,and then decreased;HF was also the lowest 2 minutes before the positive reset,and then gradually increased;LF/HF was at The time of positive reset is the highest,and it decreases after returning to supine position.When comparing the three groups of LF,it was found that the vascular inhibitory type was significantly lower than the mixed type in the time period before positive reduction(P<0.01);when compared between the three groups of HF,it was found that the vascular inhibitory type was compared with the mixed type in the time period before positive reduction.Significantly lower(P<0.01);no statistically significant difference was found when comparing the three groups of LF/HF.Comparison of the three subtypes before and after the positive reduction of the Head-up tilt test,the comparison between the LF found that the Vasodepressor LF 2 minutes before the positive reduction is lower than the Mixed LF(P<0.01)30 seconds before the positive reduction Mixed type and Cardioinhibitory LF(P<0.01);Vasodepressor LF at the time of positive reset is smaller than Mixed and Cardioinhibitory LF(P<0.01);HF comparison found that Vasodepressor HF is lower than Mixed type 4 minutes before positive reset HF(P=0.01);Vasodepressor HF 2 minutes before positive reduction was lower than Mixed HF(P<0.01);30 seconds before positive reduction,there were differences between the three subtypes(P<0.01);At the time of positive reduction,the Cardioinhibitory HF was higher than the mixed and Vasodepressor HF(P<0.01);no statistically significant difference was found in LF/HF during the whole Head-up tilt test,the difference between the Vasodepressor and mixed meanRR was statistically significant P<0.01,and the triangular index P<0.05.Conclusion:Our results show that:1.Sympathetic nerve activity in patients with vasovagal syncope showed a progressive increase in the Head-up tilt test.sympathetic nerve activity after being upright is higher than that in supine position,and the drug-tested upright position is higher than that in upright position.After returning to supine position,it returns to the basic At the supine level,the vagus nerve activity is the opposite.It decreases progressively until it rises when the syncope occurs.After returning to the supine position,the vagus nerve activity is restored to the basic supine position.2.In the three subtypes of vasovagal syncope,the sympathetic nerve and vagus nerve change intensity are different in the Head-up tilt test,and the Vasodepressor sympathetic nerve and vagus nerve change intensity are weaker than the Mixed.