| The first part:Clinical characteristics in unexplained syncope patients diagnosed by the head-up tilt testBackgroundVasovagal syncope (VVS) is the most common type of syncope. It refers to syncope caused by vasodepressor and cardioinhibition, which were mediated by many kinds of vagal reflexes. The aim of this study was to evaluate the head up tilt test (HUTT) diagnosis of unexplained syncope (UPS) patients to analysis clinical characteristics.MethodsA total of 1223 patients who received HUTT in Fuwai hospital from 2008-08 to 2012-12 were recruited. Demographic data, blood pressure and heart rate at rest were collected. The HUTT comprised a 30 min basic head up tilt test (BHUT) and 20 min nitroglycerin head up tilt test (NHUT). According to ECG and blood pressure changes, the HUTT positive patients included vasodepressor type, cardioinhibitory type and mixed type. Comparisons between patients with different VVS diagnosis by t test, Chi-square test, rank sum test and Logistic regression model. Then we analyzed VVS between groups of age, sex, blood pressure and heart rate at rest to identify possible risk factors.ResultsThe overall detected positive rate of HUTT was 51%(624/1223 cases) and higher among women compared with men (60.09% vs 39.89%, P<0.05). The highest positive rate was found in the<20 years group, and it decreased with the increment of age before 40 years, then slightly increased for patients aged 40 years or older. The mixed type accounted for 51.4%(321/624 cases), vasodepressor type for 28.7%(179/624 cases) and cardioinhibitory type for 19.9%(124/624 cases). There was no significant effect by gender on detected positive type, but it was influenced by age for men and women (men:P=0.016, women: .P=0.004). During the basic phase, most positive reactions (74.8%) occurred between 17.5 and 27.5 (median:22.5) min. However, during the nitroglycerin provocation phase, most positive reactions (81.9%) occurred between 5.0 and 10.0 (median:7.5) min.Detected positive rate of HUTT decreased with the increment of blood pressure. Both blood pressure and heart rate at rest had no significant effect on positive type and time to positive reaction during the basic phase and the nitroglycerin provocation phase.ConclusionGender, age and blood pressure at rest have influence on results in WS patients diagnosed by HUTT in Chinese. reaction during the basic phase and the nitroglycerin provocation phase.ConclusionGender, age and blood pressure at rest have influence on results in WS patients diagnosed by HUTT in Chinese.The second part:Heart rate and coronary heart disease among Beijing adultsBackgroundHeart rate is an indicator of autonomic nervous system tone. Prospective studies have reported that elevated heart rate and reduced heart rate are major risk factors for coronary heart disease (CHD). But some researches suggested that the association between heart rate and CHD is mainly mediated by elevated blood pressure. Therefore, we aimed to examine the association between heart rate and CHD among Beijing residents by the cross-sectional study.MethodsParticipants of the present investigation were from the adults in the surveillance of non-communicable chronic diseases in Beijing. A total of 19523 participants (8823 men, 10700 women) aged 18 to 79 years were recruited. The survey included demographic information, behavior risk factors, health and disease data, anthropometric and laboratory measurements. According to heart rate level, participants were divided into 4 group:<60, 60-79,80-99 and>100 beat per minute (bpm). The relationship between heart rate and the risk of CHD was examined by Logistic regression model.ResultsThere were 898 cases of CHD, and the prevalence of CHD was 4.30% and 4.85% among men and women respectively. The heart rate was found to be lower in CHD patients than non-CHD participants. For population, after adjusting for age, sex, antihypertensive, systolic blood pressure, BMI, smoking, alcohol use, education status, compared with the participants of heart rate 60-79 bpm, the odds ratios (95%CIs) of CHD were 1.26(0.93,1.71), 0.95(0.81,1.13) and 0.80(0.48,1.29) respectively for those with a heart rate of<60,80-99 and ≥100 bpm. For normotensive, after adjusting for age, sex, BMI, smoking, alcohol use, education status, the odds ratios (95%CIs) of CHD for paticipants with a heart rate of <60, 60-79,80-99 and ≥100 bpm were 1.63(0.98,2.71),1,0.88(0.64,1.21) and 1.57(0.55,4.45). The prevalence of CHD is highest for the subgroup of hypertension and heart rate of <60 bpm.ConclusionsThe heart rate is lower in CHD patients than non-CHD participants. And the reduced heart rate may increase the odds ratio of CHD. |
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