Gao Sinsia A, Johansson Mats, Hammarén Anna, Nordberg Martin, Friberg Peter
Dept. of Clinical Physiology, Sahlgrenska University Hospital, 413 45 Göteborg, Sweden.
Clin Auton Res. 2005 Feb;15(1):21-8. doi: 10.1007/s10286-005-0224-4.
Spontaneous baroreflex sensitivity (BRS), the reflex heart rate modulation in response to blood pressure changes (predominantly an index of cardiac vagal activity) and temporal QT variability (an index of myocardial repolarization) have been demonstrated to convey important prognostic information. The information about reproducibility of BRS and temporal QT variability is limited and there is lack of information regarding patients with cardiovascular diseases. We investigated reproducibility of spontaneous BRS using the sequence technique and temporal QT variability index (QTVI) in terms of intra-, interexaminer and within-subject variability in end-stage renal disease patients (ESRD, n=17, age 55+/-14 years) and healthy subjects (HS, n=29, age 32+/-12 years, P<0.01). ECG and blood pressure (Portapres) were recorded on two separate days and BRS and QTVI were evaluated by two independent examiners. The mean heart rate was similar in ESRD patients in comparison to healthy controls, whereas the mean arterial pressure was 13 % higher in ESRD patients (P<0.01). Spontaneous BRS was 62% lower (P<0.01) and QTVI was 41% higher in ESRD patients (P<0.01) compared to healthy subjects, respectively. Coefficient of variation (CV) of within-subject reproducibility of BRS and QTVI measurements was moderate (BRS: 33 % for ESRD, 27% for HS; QTVI: 40% for ESRD, 18% for HS). The 95% limit of within-subject reproducibility of BRS measurements was 3.8 ms/mm Hg for ESRD patients and 8.1 ms/mm Hg for healthy subjects; whereas the 95% limit of reproducibility of within-subject reproducibility of QTVI measurements was 0.73 for ESRD patients and 0.55 for healthy subjects. Concordance correlation coefficients of within-subject variability of BRS and QTVI were between 0.74 and 0.83 in both groups. CV of intra- and inter-examiner reproducibility of BRS and QTVI measurements in both groups ranged between 1 and 11%. In conclusion, the intra- and inter-examiner reproducibility/agreement of BRS and QTVI were high, whereas the within-subject reproducibility of these two methods was moderate, in both ESRD patients and healthy subjects. Thus, small differences in BRS and QTVI in longitudinal/interventional studies should be interpreted with caution.
自发性压力反射敏感性（BRS），即对血压变化的反射性心率调节（主要是心脏迷走神经活动的指标）以及QT间期变异性（心肌复极化的指标）已被证明可传达重要的预后信息。关于BRS和QT间期变异性可重复性的信息有限，且缺乏有关心血管疾病患者的信息。我们采用序列技术研究了终末期肾病患者（ESRD，n = 17，年龄55±14岁）和健康受试者（HS，n = 29，年龄32±12岁，P<0.01）的自发性BRS的可重复性以及QT间期变异性指数（QTVI），涉及组内、不同检查者间以及受试者自身的变异性。在两个不同日期记录心电图和血压（Portapres），并由两名独立检查者评估BRS和QTVI。与健康对照相比，ESRD患者的平均心率相似，而ESRD患者的平均动脉压高13%（P<0.01）。与健康受试者相比，ESRD患者的自发性BRS分别低62%（P<0.01），QTVI高41%（P<0.01）。BRS和QTVI测量的受试者自身可重复性的变异系数（CV）为中等（BRS：ESRD患者为33%，HS为27%；QTVI：ESRD患者为40%，HS为18%）。ESRD患者BRS测量的受试者自身可重复性的95%界限为3.8 ms/mm Hg，健康受试者为8.1 ms/mm Hg；而QTVI测量的受试者自身可重复性的95%界限，ESRD患者为0.73，健康受试者为0.55。两组中BRS和QTVI的受试者自身变异性的一致性相关系数在0.74至0.83之间。两组中BRS和QTVI测量的检查者内和检查者间可重复性的CV在1%至11%之间。总之，在ESRD患者和健康受试者中，BRS和QTVI的检查者内和检查者间可重复性/一致性较高，而这两种方法的受试者自身可重复性为中等。因此，在纵向/干预性研究中，BRS和QTVI的微小差异应谨慎解释。
