| Background Vasovagal syncope is one of the most common causes of syncope,which induce life and psychological harm due to repeated attacks.Head Up Tilt Test is the "gold standard" for the diagnosis of vasovagal syncope.Previous studies mainly focused on the tilt angle,medication used during the stimulation,duration of stimulation and so on,while in recent years,the electrical characteristics of head up tilt test among patients with vasovagal syncope have become a new hot spot.Objective The aim of this study is to explore features for changes of cardiac electrical parameters in patients with vasovagal syncope.Method Patients in the Fuwai Hospital from August 2015 to May 2016 were diagnosed with vasovagal syncope and underwent an upright tilt test.The blood pressure,heart rate and 12-lead electrocardiogram during the upright tilt test were recorded simultaneously.According to the results of the tilt table test,they were divided into positive group and negative group.To observe the dynamic changes of the two groups of patients in the supine position,the basic test stage,drug test stage and positive ECG,the changes and differences of the ECG parameters during the upright tilt test were analyzed.Result ?This study included a total of 502 people,of which 244 patients with head up tilt test positive group(70 men and 174 women,accounting for 28.7%vs 71.3%),tilt test negative group 258 patients(138 men,and 120 women,accounting for 53.5%vs 46.5%),in head up tilt test positive group the proportion of women was significantly higher than that in the negative group(p<0.05).? Compared with the baseline supine phase,systolic blood pressure were decreased,diastolic blood pressure increased,and the heart rate increased in both positive group and negative group(p<0.05).In the positive group,systolic blood pressure,diastolic blood pressure and heart rate fell to a lower level(p<0.05)when syncope occurred.The T wave duration had no change in the basic experimental stage,and a slightly shortened trend in the drug test phase(p<0.05).PR interval showed a trend of shortening(p<0.05).The trend of change was similar between the positive group and the negative group.P wave duration of negative group showed a trend of shortening(p<0.05).In the positive group,there was a trend of shortening(p<0.05)at baseline,but there was no statistical significance between the two groups before and after the examination.QRS wave axis in the negative group showed a trend of left deviation(p<0.05),but in the positive group,left deviation showed only in and after syncope.?Compared with the baseline test 2.5 minutes,systolic blood pressure of both positive and negative group showed a trend of decreasing(p<0.05),diastolic blood pressure gradually increased(p<0.05),and the heart rate gradually increased(p<0.05).Furthermore,systolic blood pressure,diastolic blood pressure and heart rate of positive group dropped to the lowest level(p<0.05)until syncope happened.P wave duration of positive group showed a trend of shortening(p<0.05)on the baseline test stage,but didn't change significantly before,during and after syncope,meanwhile it decreased(p<0.05)in the drug test stage.QRS of negative group was shorten(p<0.05)at the end of the examination,but the positive group had no change.T wave duration of positive group showed a tendency to shorten(p<0.05)before syncope,while in negative group it showed a tendency to shorten(p<0.05)in the drug test period and extension(p<0.05)at the end of examination.PR interval of positive group on the baseline stage,before and during syncope showed a trend of shortening(p<0.05),but not change significantly at the end of the test;in negative group there was no significant change in the experimental stage,and only shorten(p<0.05)in drug test stage while extended(p<0.05)at the end of the examination.QTC of positive group was decreased(p<0.05)before and during syncope,but there was no significant change.P wave axis of positive group showed a tendency of left deviation(p<0.05)during syncope,after syncope and at the end of examination;while in negative group there was a slight right deviation tendency in the baseline stage and the drug test stage(p<0.05).There was no change in QRS wave axis in both negative and positive group.T wave axis of positive group showed a trend of left deviation(p<0.05)generally,while right deviation(p<0.05)after syncope and at the end of the examination;the negative group showed a trend of left deviation(p<0.05).?The systolic and diastolic blood pressure of positive group at each stage were lower than negative group(p<0.05),heart rate of positive group were higher than those of negative group on the basis of experimental stage and before syncope(p<0.05),but lower than those of negative group during syncope,after syncope and at the end of examination(p<0.05).P wave of positive group is higher than that of negative group during syncope and at the end of examination(p<0.05).QRS of positive group was lower than that of negative group in baseline stage.T wave of positive group was lower than that of negative group in the baseline stage and drug test stage(p<0.05).PR interval of positive group was lower than that of negative group in the baseline stage,but higher at the end of test(p<0.05).QTC of positive group was significant lower than that of negative group before syncope,but significant higher after syncope(p<0.05).P wave axis of positive group was more right deviation than that of negative group(p<0.05),but significant left deviation during syncope,after syncope and at the end of examination(p<0.05).There was no statistical significance between the two groups at each test stage.T wave axis of positive group was significantly higher than that of negative group after syncope and at the end of examination(p<0.05).Conclusion ?The systolic and diastolic blood pressure of the positive group were lower than those of the negative group at each time point.The heart rate of the positive group was higher than that of the negative group in the baseline test and syncope,while it was lower in the syncope and end of the test.?On the positive group,the diastolic blood pressure decreased earlier than negative group before syncope happening.?Compare to basic tile position,the P-wave duration of the positive group was shorten in baseline test and drug test stage,while P wave axis shows right deviation in the same stages,but no this kind of trend when before and after syncope.?Compare to baseline test 2.5 minutes,P wave duration,PR interval,and T wave duration of positive group are shorten,while those of negative group are only shorten in drug test when glyceryl triturate was provoked.P wave axis of positive group shown left deviation when syncope occurred,while it shown right deviation in drug test for positive group.?P wave duration in positive group is significantly longer than that of negative group,QRS duration,T wave duration,PR interval of positive group are shorter than those of negative group in baseline test.?QTc of positive group before and onset of syncope is shorter than that of in supine position stage and BHUT 2.5 minutes,while QTc before syncope is shorter than that of negative.The current study indicated that changes of blood pressure,heart rate and electrocardiogram parameters in patients with vasovagal syncope can be predicted by the change of autonomic nerve function,blood pressure,heart rate and electrocardiogram parameters during the upright tilt test. |
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