To study the role of autonomic nervous system in the period of developing syncope induced by head-up tilt test(HUT), we analysed the changes of heart rate power spectral density(HRPSD) in 50 patients with unexplained ...To study the role of autonomic nervous system in the period of developing syncope induced by head-up tilt test(HUT), we analysed the changes of heart rate power spectral density(HRPSD) in 50 patients with unexplained syncope, including 15 positive patients (Group 1) and 35 negative patients(Group 2), and 15 negative healthy persons(Group 3) in 5 minute periods before and after tilting and 5 minutes before the end of test. HRPSD and their changes in total(T), very low-frequence(VLF), low-frequence(LF), high-frequence(HF) and the ratio of low/high frequence(LF/HF) were similar (P>0.05) 5 minutes before and after tilting among three groups. Five minutes before the end of test, Group 1 had obvious increase of T, VLF, LF and LF/HF while Group 2 and 3 had not such significant changes. There was significant difference(P<0.01) compared Group 1 with Group 2, 3. The results showed that the abnormal regulatory function of autonomic nervous system played an important role in the mechanism of symcope induced by HUT, the positive group had abnormal increase of sympathetic tone and imbalance of sympathetic/parasympathetic neural tone before syncope appeared.展开更多
A heavy-ion irradiation experiment is studied in digital storage cells with different design approaches in 130？nm CMOS bulk Si and silicon-on-insulator （SOI） technologies. The effectiveness of linear energy transf...A heavy-ion irradiation experiment is studied in digital storage cells with different design approaches in 130？nm CMOS bulk Si and silicon-on-insulator （SOI） technologies. The effectiveness of linear energy transfer （LET） with a tilted ion beam at the 130？nm technology node is obtained. Tests of tilted angles θ=0 ° , 30 ° and 60 ° with respect to the normal direction are performed under heavy-ion Kr with certain power whose LET is about 40？MeVcm 2 /mg at normal incidence. Error numbers in D flip-flop chains are used to determine their upset sensitivity at different incidence angles. It is indicated that the effective LETs for SOI and bulk Si are not exactly in inverse proportion to cosθ , furthermore the effective LET for SOI is more closely in inverse proportion to cosθ compared to bulk Si, which are also the well known behavior. It is interesting that, if we design the sample in the dual interlocked storage cell approach, the effective LET in bulk Si will look like inversely proportional to cosθ very well, which is also specifically explained.展开更多
Objective To study thechanges of baroreflex sensitivity (BRS) during head - up tilt test (HUT) in patients with vasovagal syncope (VS), and to examine the relationship between baroreflex sensitivity and neurohormonal ...Objective To study thechanges of baroreflex sensitivity (BRS) during head - up tilt test (HUT) in patients with vasovagal syncope (VS), and to examine the relationship between baroreflex sensitivity and neurohormonal factors. Furthermore, to investigate the effects of the changes of BRS on VS. Methods Forty - two patients with unexplained syncope (Among the 42 patients, there were 22 patients with positive HUT and 20 patients with negative HUT respectively) and 20 healthy volunteers (with negative HUT) underwent passive head - up tilt testing, Ante-cubital vein blood samples were taken before and after HUT, or at syncope. The fasting plasma endothelin , serum nitric oxide (NO), serum NE were measured, the BRS was assessed on the basis of the linear regression slope the RR interval versus systolic arterial blood pressure during the increment in blood pressure after intravenous administration of phenylephrine. Results (1) During the syncope, the BRS significantly reduced in HUT(+) group than baseline. At the end of tilt, the level of plasma ET, serum NO in patients with positive HUT significantly increased compared with baseline or normal controls, and the plasma concentration of NE also had the trend of increase. (2) By multiple regression analysis, a significant negative correlation was found between baroreceptor sensitivity and the plasma ET, NO at the end of HUT in patients with positive HUT, but there was no relationship between BRS and NE. Conclusions During the syncope occure, the BRS in patients with VS decreased significantly compared with normal controls. The abnormal plasma ET, NO concen-tration might contribute to the mechanism of VS.展开更多
Objective: to evaluate cilazapril in vasovagal syncope treatment. Method: eighty\|six cases of VVS patients found positive in TTT tilt were medicated with 2.5 mg cilazapril daily for three months and followed up by TT...Objective: to evaluate cilazapril in vasovagal syncope treatment. Method: eighty\|six cases of VVS patients found positive in TTT tilt were medicated with 2.5 mg cilazapril daily for three months and followed up by TTT. Results: seven cases quit due to cough or unexplained reason; 79 VVS patients had no more fainting spells; 75.95% of TTT results of patients changed to negative after 3 months therapy. The before and after cilazapril treatment average blood pressures (taken in lying position) were 121/73 mm Hg (1 mm Hg= 0.133kPa) and 120/76 mm Hg respectively ( P > 0.05); and mean heart rates were 68.63±12.37/min and 70.13±13.15/min respectively with no significant changes ( P > 0.05). Conclusion: Cilazapril was effective in treatment of VVS; did not affect normal blood pressure and heart rate; was safe; and had little side effect.展开更多
<strong>Aim</strong><span><span><span style="font-family:;" "=""><strong>:</strong> To describe post-infectious neurological aspects of COVID-19 in a ...<strong>Aim</strong><span><span><span style="font-family:;" "=""><strong>:</strong> To describe post-infectious neurological aspects of COVID-19 in a patient with progressive post-infectious peripheral (PNS), autonomic (ANS) and central nervous system (CNS) involvement due to SARS-CoV-2 infection. <b>Background</b> <b>and</b> <b><strong>Purpose</strong></b><strong>:</strong> A variety of neurological manifestations have been described in association with Covid-19, however</span></span></span><span><span><span style="font-family:;" "="">,</span></span></span><span><span><span style="font-family:;" "=""> progressive multisystem neurological aspects have not been described. <b><strong>Methods</strong></b><strong>:</strong> A case report detailing the history, examination, and infectious serology associated with SARS-CoV-2, and subsequent neurodiagnostic laboratory testing and treatment. <b><strong>Results</strong></b><strong>:</strong> Neurodiagnostic laboratory studies showed large-fiber demyelinating sensorimotor and painful small fiber sensory polyneuropathy, orthostatic hypotension, and hypometabolism of bilateral anterior and mesial temporal lobes with a possible frontal seizure focus. Treatment was initiated with high-dose immune globulin therapy. <b><strong>Conclusions</strong></b><strong>:</strong> The combination of PNS, ANS <span>and</span> CNS involvement in this patient was associated with post-infectious acquired immunity to SARS-CoV-2.</span></span></span>展开更多
Objective:The head-up tilt test(HUTT)is widely used but is time-consuming and not cost-effective to evaluate patients with vasovagal syncope(VVS).The present study aims to verify the hypothesis that ambulatory blood p...Objective:The head-up tilt test(HUTT)is widely used but is time-consuming and not cost-effective to evaluate patients with vasovagal syncope(VVS).The present study aims to verify the hypothesis that ambulatory blood pressure(BP)monitoring(ABPM)and the simplistic tilt test may be potential alternatives to the HUTT.Methods:The study consecutively enrolled 360 patients who underwent the HUTT to evaluate VVS.BP),heart rate(HR),and BP/HR ratios derived from ABPM and the simplistic tilt test were evaluated to predict the presence,pattern,and stage of syncope during the HUTT.Results:Mixed response was the commonest pattern,and syncope occurred frequently with infusion of isoproterenol at a rate of 3μg/min.During the simplistic tilt test,the cardioinhibitory group had higher tilted BP/HR ratios than the vasodepressor group,while the vasodepressor group had a faster tilted HR and a larger HR difference than the cardioinhibitory group.The higher the BP/HR ratio in the tilted position,the higher the isoproterenol dosage needed to induce a positive response.During ABPM,BP/HR ratios were signifi cantly higher in the cardioinhibitory group than in the vasodepressor group.The higher the ABPM-derived BP,the higher the dosage of isoproterenol needed to induce syncope.There were signifi cant correlations in BP/HR ratios between ABPM and the supine position in the vasodepressor group,while signifi cant correlation was found only for the diastolic BP/HR ratio between ABPM and the tilted position in the cardioinhibitory group.The mixed pattern shared correlative features of the other two patterns.Conclusion:ABPM and the simplistic tilt test might be used as promising alternatives to the HUTT in VVS evaluation in clinical settings.展开更多
Introduction: It is common to find people sent to perform a Head Up Tilt Test (HUT) who suffered a single syncope, or syncopes that occur during certain periods and never appear again. We wonder how these people are d...Introduction: It is common to find people sent to perform a Head Up Tilt Test (HUT) who suffered a single syncope, or syncopes that occur during certain periods and never appear again. We wonder how these people are different from those who have never had syncope. Methods: We found 300 patients who suffered only one (unique) or a maximum of 5 vasovagal syncopes during their life. And their HUT was positive for vasovagal dysautonomia. We compared them, with 120 healthy volunteers who have never had syncope. We try to explain how some constitutional predisposing factors act in these patients, and are associated with environmental triggers to precipitate the syncope. Results: We found differences between cases and controls in predisposing factors such as: heredity, joint hypermobility, baroreflex failure, venous compliance and some neurological diseases. Then an environmental factor acts as a trigger for syncope: prolonged standing, stress, pain and emotions, dehydration, use of certain drugs, abundant food. Conclusions: There are people with minimally expressed vasovagal dysautonomia who have an organic predisposition to present vasovagal syncopes (heredity, joint hypermobility, baroreflex failure, venous compliance, some neurological diseases, etc.). But this predisposition is not enough by itself to produce syncopes. One or more environmental factors must be added, acting as a trigger that would be the reason why these episodes are so infrequent.展开更多
To investigate age and sex distribution of vasovagal syncope （VVS） patients undergoing head-up tilt table test （HUTT） at a tertiary hospital. The details of syncope patients who underwent HUTT at our department of...To investigate age and sex distribution of vasovagal syncope （VVS） patients undergoing head-up tilt table test （HUTT） at a tertiary hospital. The details of syncope patients who underwent HUTT at our department of cardiac function from January 2004 to December 2010 were reviewed. Of the 1 799 patients who underwent the HUTT, 854 tested positive, of which 558 （65.3%） were women, which were more than the women in the negative group （450, 47.6%） （p〈0.05）. VVS patients showed a bimodal age distribution between 11 and 20 years of age and in the fourth decade. In almost all age groups, mixed response was the highest compared with vasodepressor and cardioinhibitory. VVS patients who underwent HUTT indicate bimodal distribution peaking before the second decade and the fourth decade. The incidence of females was twice that of males before the sixth decade, and old age occupies a small percentage of VVS with no other comorbidities.展开更多
Background Syncope is common in children and adolescents, with 15% estimated to have had at least one syncopal episode by age 18. In recent years, an increasing number of children, especially girls at their school age...Background Syncope is common in children and adolescents, with 15% estimated to have had at least one syncopal episode by age 18. In recent years, an increasing number of children, especially girls at their school age, have developed unexplained syncope. The mechanism of an unexplained syncope exhibited by children is incompletely studied; the association between different hemodynamic patterns and clinical features is also not clear. The aim of the study was to investigate the hemodynamic patterns of children with unexplained syncope and to examine the clinical relevance. Methods Two hundred and eight children [87 boys, 121 girls, aged 3-19 years, mean （11.66±2.72） years] were selectively recruited from May 2000 to April 2006 when they presented syncope as their main complaint at the Multi-center Network for Childhood Syncope in Beijing, Hunan Province, Hubei Province, and Shanghai of China. All of the patients underwent head-up tilt tests; data were analyzed using SPSS version 10.0 for Windows. Continuous variables were expressed as the mean± standard deviation. Dichotomous variables were compared through a X^2 test. A value of P〈0.05 （two sided） was regarded as statistically significant. Results The age distribution of children with syncope was approximately normal. Head-up tilt tests was positive in 155 children, and the incidence of positive response of the baseline head-up tilt test for diagnosing unexplained syncope was 50.48%. The sensitivity value and diagnostic value of sublingual nitroglycerin head-up tilt test were both 74.52%. The hemodynamic pattern was normal in 53 children. The 155 children, who were positive in head-up tilt tests, showed signs of postural orthostatic tachycardia syndrome （60, 28.8%）, the vasoinhibitory pattern （72, 34.6%）, the cardioinhibitory pattern （5, 2.4%）, and the mixed pattern （18, 8.7%）. The gender distribution between the two age groups （age 〈 12 years vs age ≥ 12 years） was not different （P〉0.05）. The distribution of hemodynamic patterns between the children of the two age groups （age 〈 12 years vs age ≥ 12 years）, and the children with different complaints （dizziness vs syncope） was significantly different （P〈0.05）, while the distribution between the children of different sexes and different lasting time of syncope （≤ 5 minutes vs 〉 5 minutes） was not significantly different （P〉0.05）. Different hemodynamic patterns were differentiated by differing syncope inducements, presymptoms, and complicated symptoms during and after syncope. Conclusion The tested girls were more prone when compared with the boys to have unexplained syncope, and the peak age was around twelve years old. The incidence of positive response of head-up tilt tests was also relatively higher for the girls. The distribution of hemodynamic patterns for different ages was different. For children with unexplained syncope, we should use head-up tilttests to distinguish the hemodynamic patterns in order to adopt rational therapeutic measures.展开更多
文摘To study the role of autonomic nervous system in the period of developing syncope induced by head-up tilt test(HUT), we analysed the changes of heart rate power spectral density(HRPSD) in 50 patients with unexplained syncope, including 15 positive patients (Group 1) and 35 negative patients(Group 2), and 15 negative healthy persons(Group 3) in 5 minute periods before and after tilting and 5 minutes before the end of test. HRPSD and their changes in total(T), very low-frequence(VLF), low-frequence(LF), high-frequence(HF) and the ratio of low/high frequence(LF/HF) were similar (P>0.05) 5 minutes before and after tilting among three groups. Five minutes before the end of test, Group 1 had obvious increase of T, VLF, LF and LF/HF while Group 2 and 3 had not such significant changes. There was significant difference(P<0.01) compared Group 1 with Group 2, 3. The results showed that the abnormal regulatory function of autonomic nervous system played an important role in the mechanism of symcope induced by HUT, the positive group had abnormal increase of sympathetic tone and imbalance of sympathetic/parasympathetic neural tone before syncope appeared.
基金Supported by the Key Laboratory of Microsatellites,Chinese Academy of Sciences
文摘A heavy-ion irradiation experiment is studied in digital storage cells with different design approaches in 130？nm CMOS bulk Si and silicon-on-insulator （SOI） technologies. The effectiveness of linear energy transfer （LET） with a tilted ion beam at the 130？nm technology node is obtained. Tests of tilted angles θ=0 ° , 30 ° and 60 ° with respect to the normal direction are performed under heavy-ion Kr with certain power whose LET is about 40？MeVcm 2 /mg at normal incidence. Error numbers in D flip-flop chains are used to determine their upset sensitivity at different incidence angles. It is indicated that the effective LETs for SOI and bulk Si are not exactly in inverse proportion to cosθ , furthermore the effective LET for SOI is more closely in inverse proportion to cosθ compared to bulk Si, which are also the well known behavior. It is interesting that, if we design the sample in the dual interlocked storage cell approach, the effective LET in bulk Si will look like inversely proportional to cosθ very well, which is also specifically explained.
文摘Objective To study thechanges of baroreflex sensitivity (BRS) during head - up tilt test (HUT) in patients with vasovagal syncope (VS), and to examine the relationship between baroreflex sensitivity and neurohormonal factors. Furthermore, to investigate the effects of the changes of BRS on VS. Methods Forty - two patients with unexplained syncope (Among the 42 patients, there were 22 patients with positive HUT and 20 patients with negative HUT respectively) and 20 healthy volunteers (with negative HUT) underwent passive head - up tilt testing, Ante-cubital vein blood samples were taken before and after HUT, or at syncope. The fasting plasma endothelin , serum nitric oxide (NO), serum NE were measured, the BRS was assessed on the basis of the linear regression slope the RR interval versus systolic arterial blood pressure during the increment in blood pressure after intravenous administration of phenylephrine. Results (1) During the syncope, the BRS significantly reduced in HUT(+) group than baseline. At the end of tilt, the level of plasma ET, serum NO in patients with positive HUT significantly increased compared with baseline or normal controls, and the plasma concentration of NE also had the trend of increase. (2) By multiple regression analysis, a significant negative correlation was found between baroreceptor sensitivity and the plasma ET, NO at the end of HUT in patients with positive HUT, but there was no relationship between BRS and NE. Conclusions During the syncope occure, the BRS in patients with VS decreased significantly compared with normal controls. The abnormal plasma ET, NO concen-tration might contribute to the mechanism of VS.
文摘Objective: to evaluate cilazapril in vasovagal syncope treatment. Method: eighty\|six cases of VVS patients found positive in TTT tilt were medicated with 2.5 mg cilazapril daily for three months and followed up by TTT. Results: seven cases quit due to cough or unexplained reason; 79 VVS patients had no more fainting spells; 75.95% of TTT results of patients changed to negative after 3 months therapy. The before and after cilazapril treatment average blood pressures (taken in lying position) were 121/73 mm Hg (1 mm Hg= 0.133kPa) and 120/76 mm Hg respectively ( P > 0.05); and mean heart rates were 68.63±12.37/min and 70.13±13.15/min respectively with no significant changes ( P > 0.05). Conclusion: Cilazapril was effective in treatment of VVS; did not affect normal blood pressure and heart rate; was safe; and had little side effect.
文摘<strong>Aim</strong><span><span><span style="font-family:;" "=""><strong>:</strong> To describe post-infectious neurological aspects of COVID-19 in a patient with progressive post-infectious peripheral (PNS), autonomic (ANS) and central nervous system (CNS) involvement due to SARS-CoV-2 infection. <b>Background</b> <b>and</b> <b><strong>Purpose</strong></b><strong>:</strong> A variety of neurological manifestations have been described in association with Covid-19, however</span></span></span><span><span><span style="font-family:;" "="">,</span></span></span><span><span><span style="font-family:;" "=""> progressive multisystem neurological aspects have not been described. <b><strong>Methods</strong></b><strong>:</strong> A case report detailing the history, examination, and infectious serology associated with SARS-CoV-2, and subsequent neurodiagnostic laboratory testing and treatment. <b><strong>Results</strong></b><strong>:</strong> Neurodiagnostic laboratory studies showed large-fiber demyelinating sensorimotor and painful small fiber sensory polyneuropathy, orthostatic hypotension, and hypometabolism of bilateral anterior and mesial temporal lobes with a possible frontal seizure focus. Treatment was initiated with high-dose immune globulin therapy. <b><strong>Conclusions</strong></b><strong>:</strong> The combination of PNS, ANS <span>and</span> CNS involvement in this patient was associated with post-infectious acquired immunity to SARS-CoV-2.</span></span></span>
基金the Guangdong Natural Science Foundation Project(2018A030313531)the Yat-Sen Scholarship for Young Scientists.
文摘Objective:The head-up tilt test(HUTT)is widely used but is time-consuming and not cost-effective to evaluate patients with vasovagal syncope(VVS).The present study aims to verify the hypothesis that ambulatory blood pressure(BP)monitoring(ABPM)and the simplistic tilt test may be potential alternatives to the HUTT.Methods:The study consecutively enrolled 360 patients who underwent the HUTT to evaluate VVS.BP),heart rate(HR),and BP/HR ratios derived from ABPM and the simplistic tilt test were evaluated to predict the presence,pattern,and stage of syncope during the HUTT.Results:Mixed response was the commonest pattern,and syncope occurred frequently with infusion of isoproterenol at a rate of 3μg/min.During the simplistic tilt test,the cardioinhibitory group had higher tilted BP/HR ratios than the vasodepressor group,while the vasodepressor group had a faster tilted HR and a larger HR difference than the cardioinhibitory group.The higher the BP/HR ratio in the tilted position,the higher the isoproterenol dosage needed to induce a positive response.During ABPM,BP/HR ratios were signifi cantly higher in the cardioinhibitory group than in the vasodepressor group.The higher the ABPM-derived BP,the higher the dosage of isoproterenol needed to induce syncope.There were signifi cant correlations in BP/HR ratios between ABPM and the supine position in the vasodepressor group,while signifi cant correlation was found only for the diastolic BP/HR ratio between ABPM and the tilted position in the cardioinhibitory group.The mixed pattern shared correlative features of the other two patterns.Conclusion:ABPM and the simplistic tilt test might be used as promising alternatives to the HUTT in VVS evaluation in clinical settings.
文摘Introduction: It is common to find people sent to perform a Head Up Tilt Test (HUT) who suffered a single syncope, or syncopes that occur during certain periods and never appear again. We wonder how these people are different from those who have never had syncope. Methods: We found 300 patients who suffered only one (unique) or a maximum of 5 vasovagal syncopes during their life. And their HUT was positive for vasovagal dysautonomia. We compared them, with 120 healthy volunteers who have never had syncope. We try to explain how some constitutional predisposing factors act in these patients, and are associated with environmental triggers to precipitate the syncope. Results: We found differences between cases and controls in predisposing factors such as: heredity, joint hypermobility, baroreflex failure, venous compliance and some neurological diseases. Then an environmental factor acts as a trigger for syncope: prolonged standing, stress, pain and emotions, dehydration, use of certain drugs, abundant food. Conclusions: There are people with minimally expressed vasovagal dysautonomia who have an organic predisposition to present vasovagal syncopes (heredity, joint hypermobility, baroreflex failure, venous compliance, some neurological diseases, etc.). But this predisposition is not enough by itself to produce syncopes. One or more environmental factors must be added, acting as a trigger that would be the reason why these episodes are so infrequent.
基金Supported by the National Natural Science Foundation of China (30972954)
文摘To investigate age and sex distribution of vasovagal syncope （VVS） patients undergoing head-up tilt table test （HUTT） at a tertiary hospital. The details of syncope patients who underwent HUTT at our department of cardiac function from January 2004 to December 2010 were reviewed. Of the 1 799 patients who underwent the HUTT, 854 tested positive, of which 558 （65.3%） were women, which were more than the women in the negative group （450, 47.6%） （p〈0.05）. VVS patients showed a bimodal age distribution between 11 and 20 years of age and in the fourth decade. In almost all age groups, mixed response was the highest compared with vasodepressor and cardioinhibitory. VVS patients who underwent HUTT indicate bimodal distribution peaking before the second decade and the fourth decade. The incidence of females was twice that of males before the sixth decade, and old age occupies a small percentage of VVS with no other comorbidities.
基金This work was supported by agrant from the National Tenth Five-year Plan Research Project of China(No.2004BA720A10).
文摘Background Syncope is common in children and adolescents, with 15% estimated to have had at least one syncopal episode by age 18. In recent years, an increasing number of children, especially girls at their school age, have developed unexplained syncope. The mechanism of an unexplained syncope exhibited by children is incompletely studied; the association between different hemodynamic patterns and clinical features is also not clear. The aim of the study was to investigate the hemodynamic patterns of children with unexplained syncope and to examine the clinical relevance. Methods Two hundred and eight children [87 boys, 121 girls, aged 3-19 years, mean （11.66±2.72） years] were selectively recruited from May 2000 to April 2006 when they presented syncope as their main complaint at the Multi-center Network for Childhood Syncope in Beijing, Hunan Province, Hubei Province, and Shanghai of China. All of the patients underwent head-up tilt tests; data were analyzed using SPSS version 10.0 for Windows. Continuous variables were expressed as the mean± standard deviation. Dichotomous variables were compared through a X^2 test. A value of P〈0.05 （two sided） was regarded as statistically significant. Results The age distribution of children with syncope was approximately normal. Head-up tilt tests was positive in 155 children, and the incidence of positive response of the baseline head-up tilt test for diagnosing unexplained syncope was 50.48%. The sensitivity value and diagnostic value of sublingual nitroglycerin head-up tilt test were both 74.52%. The hemodynamic pattern was normal in 53 children. The 155 children, who were positive in head-up tilt tests, showed signs of postural orthostatic tachycardia syndrome （60, 28.8%）, the vasoinhibitory pattern （72, 34.6%）, the cardioinhibitory pattern （5, 2.4%）, and the mixed pattern （18, 8.7%）. The gender distribution between the two age groups （age 〈 12 years vs age ≥ 12 years） was not different （P〉0.05）. The distribution of hemodynamic patterns between the children of the two age groups （age 〈 12 years vs age ≥ 12 years）, and the children with different complaints （dizziness vs syncope） was significantly different （P〈0.05）, while the distribution between the children of different sexes and different lasting time of syncope （≤ 5 minutes vs 〉 5 minutes） was not significantly different （P〉0.05）. Different hemodynamic patterns were differentiated by differing syncope inducements, presymptoms, and complicated symptoms during and after syncope. Conclusion The tested girls were more prone when compared with the boys to have unexplained syncope, and the peak age was around twelve years old. The incidence of positive response of head-up tilt tests was also relatively higher for the girls. The distribution of hemodynamic patterns for different ages was different. For children with unexplained syncope, we should use head-up tilttests to distinguish the hemodynamic patterns in order to adopt rational therapeutic measures.
