Depressed cardiac autonomic modulation in patients with chronic kidney disease

Introduction: A dysfunctional autonomic nervous system (ANS) has also been recognized as an important mechanism contributing to the poor outcome in CKD patients, with several studies reporting a reduction in heart rate variability (HRV). Objective: Evaluate the sympathovagal balance in patients with chronic kidney disease on conservative treatment. Methods: In a cross-sectional study, patients with CKD stages 3, 4 and 5 not yet on dialysis (CKD group) and age-matched healthy subjects (CON group) underwent continuous heart rate recording during two twenty-minute periods in the supine position (pre-inclined), followed by passive postural inclination at 70° (inclined period). Power spectral analysis of the heart rate variability was used to assess the normalized low frequency (LFnu), indicative of sympathetic activity, and the normalized high frequency (HFnu), indicative of parasympathetic activity. The LFnu/HFnu ratio represented sympathovagal balance. Results: After tilting, CKD patients had lower sympathetic activity, higher parasympathetic activity, and lower sympathovagal balance than patients in the CON group. Compared to patients in stage 3, patients in stage 5 had a lower LFnu/HFnu ratio, suggesting a more pronounced impairment of sympathovagal balance as the disease progresses. Conclusion: CKD patients not yet on dialysis have reduced HRV, indicating cardiac autonomic dysfunction early in the course of CKD.引言：自主神经系统（autonomic nervous system, ANS）功能障碍已被证实是导致慢性肾脏病（chronic kidney disease, CKD）患者预后不良的重要机制之一，多项研究均报道此类患者存在心率变异性（heart rate variability, HRV）降低的情况。 研究目的：评估接受保守治疗的慢性肾脏病患者的交感迷走平衡状态。 研究方法：本研究为横断面研究，纳入尚未接受透析的CKD 3、4、5期患者（CKD组）以及年龄匹配的健康受试者（CON组）。所有受试者均接受连续心率记录：先于仰卧位完成两个20分钟的记录阶段（倾斜前阶段），随后以70°角度进行被动体位倾斜（倾斜阶段）。采用心率变异性功率谱分析法，分别评估反映交感神经活动的归一化低频成分（normalized low frequency, LFnu）与反映副交感神经活动的归一化高频成分（normalized high frequency, HFnu），并以LFnu/HFnu比值作为交感迷走平衡的评价指标。 研究结果：体位倾斜后，CKD组患者的交感神经活动水平低于CON组，副交感神经活动水平更高，交感迷走平衡状态更差。与CKD 3期患者相比，CKD 5期患者的LFnu/HFnu比值更低，提示随着疾病进展，交感迷走平衡的损伤程度更为显著。 研究结论：尚未接受透析的慢性肾脏病患者存在心率变异性降低的情况，提示该病病程早期即已出现心脏自主神经功能障碍。