Sangkatumvong Suvimol, Coates Thomas D, Wood John C, Meiselman Herbert J, Kato Roberta, Detterich Jon A, Bush Adam, Khoo Michael C K
Biomedical Engineering Department, University of Southern California, Los Angeles, CA 90089, USA.
Annu Int Conf IEEE Eng Med Biol Soc. 2010;2010:1626-9. doi: 10.1109/IEMBS.2010.5626649.
Sickle cell anemia (SCA) is a genetic disease which is characterized by painful episodes of vascular occlusions. In the present study, we investigated a potential contribution of the autonomic nervous system (ANS) in initiating such episodes. We observed prominent decreases in microvascular perfusion in response to spontaneous sighs, which may increase the likelihood of red blood cell polymerization followed by vascular occlusions in SCA patients. Time-varying spectral analysis of heart rate variability (HRV), based on recursive least squares estimation, was employed to study the modulation of the ANS in response to sighs. To improve robustness of the spectral estimation while retaining its ability to track rapid changes, we propose a time-varying parameter estimate variability reduction (TV-PEVR) technique. Because respiration patterns can vary considerably across subjects, we employed a time-varying autoregressive with exogenous input (TV-ARX) model to adjust for the effect of respiration patterns on the HRV indices. Results from 8 SCA subjects and 9 normal controls suggested that the cardiac ANS responses to sighs are not different between the two groups, after adjusting for the effect of post-sigh respiration. However, the peripheral sympathetic response in SCA appeared to be enhanced in this group relative to normals, and sighs may play a role in initiation of vaso-occlusive events in this group of patients.
镰状细胞贫血（SCA）是一种遗传性疾病，其特征为血管阻塞引起的疼痛发作。在本研究中，我们调查了自主神经系统（ANS）在引发此类发作中的潜在作用。我们观察到，自发叹息会导致微血管灌注显著减少，这可能会增加SCA患者红细胞聚合继而发生血管阻塞的可能性。基于递归最小二乘估计的心率变异性（HRV）时变频谱分析被用于研究ANS对叹息的调节作用。为了在保持跟踪快速变化能力的同时提高频谱估计的稳健性，我们提出了一种时变参数估计变异性降低（TV-PEVR）技术。由于不同受试者的呼吸模式差异很大，我们采用了带外生输入的时变自回归（TV-ARX）模型来调整呼吸模式对HRV指标的影响。8名SCA受试者和9名正常对照的结果表明，在调整叹息后呼吸的影响后，两组对叹息的心脏ANS反应并无差异。然而，相对于正常人，SCA组的外周交感神经反应似乎增强了，叹息可能在该组患者血管闭塞事件的引发中起作用。
