| Backgrounds and Purposes:Vasovagal syncope (VVS) is a special but common type of syncope, which is accounted for about 70% of unexplained syncope.Tilt-table test (TTT) is an important diagnostic management of vvS. Generally speaking, during TTT, patients change from supine to tilt position, about 300~800ml blood stagnates in the veins of lower limbs. Ventricular preload is reduced by excessive venous pooling. This leads to a vigorously contracting of ventricle. The heart itself is involved in this reflex by virtue of the presence of mechanoreceptors and C-fibers. Those afferent C-fibers project centrally to the dorsal vagal nucleus of the medulla. The ultimate consequence is an increasement in vagal tone, which in turn causes vasodilation and bradycardia. Upon to the positive results of TTT, there are vosodepressor type, cardioinhibitory type, mixed type of VVS.In general, the available therapeutic options for WS are mainly pharmacological therapy and cardiac pacing. We find angiotensin converting enzyme inhibitors-Cilazapril is effective in treatment of WS.The detail of pathophysiology of VVS now is still not very clear. Moreover, various types of WS patients may have different pathophysiology. Autonomic nervous system,humoral modulation and other mechanisms may take part in this course. So we choose different types of syncope patients and patients who have processed positive TTT, now examine TTT again after taking Cilazapril for three months. We measure their renin-angiotensin-aldosterone-system (RAAS) level change and use heart rate variability (HRV) to analyze the fluctuation of autonomic nervous system during TTT.MethodsStudy population and groupingThe patients who did not take cilazapril and examined the TTT for the first time were the unexplained syncope patients came from GOPD or inpatient department of our hospital during Oct, 2002-Apr, 2003, totally 84 patients. In addition, 18 patients who had been diagnosed WS for positive TTT came to examine TTT again after taking cilazapril for three months.Protocol for TTT, HRV analysis and hormone measurementAll of the patients took TTT, the process of TTT and the evaluation of the results was depended on the suggestion from Chinese cardiac disease Journal edition committee, TTT practice group. We recorded HRV during TTT and used multiple functional electric cardiac analyzer to analyze the frequency domain of each five-minute. 0.04-0.15HZ was defined as low frequency (LF), 0.15-0.4HZ was defined as high frequency (HF). LF gives mainly a measure of sympathetic activity, and HF reflects parasympathetic. The ratio LF/HF provides a measure of the sympathovagal balance. We took blood sample before tilt and after the end of TTT, and used isotope radiaoimmunoassay to measure the level of plasma renin activity ( PRA), angiotensin II (Ag II), aldosterone (ALD).Statistical AnalysisAll results were shown as meanD. Paired data intragroup comparisons were performed using Paired-samples t test. Multiple intragroup comparisons were performed using Univariate ANOVA. Multiple between-group comparisons were performed usingOne-way ANOVA. Pairwise multiple comparisons tested the difference between each pair of means by using LSD. Differences were considered significant at the level of P<0.05.Results1 Results of TTT84 patients included 5 patients with positive baseline tilt table test, 5 patients who could not endure pharmacological provocation-tilt table test, 4 patients who were cardioinhibitory type with positive pharmacological provocation-tilt table test. Because these three types of patients were too few to compare with other types, we excluded them. The remained 70 patients all joined pharmacological provocation-tilt table test. According response to TTT, 24 patients had negative results, 23 patients were mixed type, 23 patients were vosodepressor type. All of 18 patients who examined TTT for the second time were negative in baseline tilt table test, so they totally joined pharmacological provocation-tilt table t... |
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