NDT Advance Access originally published online on February 22, 2005
Nephrology Dialysis Transplantation 2005 20(5):1011-1012; doi:10.1093/ndt/gfh670
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Reply
Sir,I thank Professor Zoccali for his interest in our paper, and for his meaningful suggestions to our study. As Zoccali et al. reported in their studies, nocturnal hypoxaemia is likely to be closely associated with autonomic dysfunction and concentric left ventricular hypertrophy (LVH) in patients with end-stage renal disease (ESRD) [1,2]. Zoccali et al. demonstrated that average nocturnal SaO2 was independently related to the deep breathing score, which was positively correlated with the SD of 24 h average heart rate, in dialysis patients. Furthermore, Zoccali et al. showed that nocturnal hypoxaemia as well as impaired parasympathetic activity was associated with the presence of concentric LVH in dialysis patients.
In the re-analysis of our data taking the heart geometry into consideration (Table 1), concentric LVH was associated inversely with SDANN in time–domain measures and positively with LF or LF/HF in frequency–domain measures in diabetic haemodialysis patients. In contrast, eccentric LVH was inversely associated with pNN50 in time–domain measures or HF in frequency–domain measures in diabetic patients. No relationship between the heart rate variability and heart geometry has been seen in non-diabetic haemodialysis patients. Therefore, impaired parasympathetic activity seems to be related to the eccentric type of LVH more strongly than the concentric type of LVH in diabetic haemodialysis patients. Sympatho-vagal imbalance in addition to impaired parasympathetic activity may be involved with concentric LVH in our diabetic haemodialysis patients.
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Intermittent hypoxic apnea can elevate peripheral sympathetic activity possibly by altering chemoreceptor control of the peripheral sympathetic activity [3,4]. Zoccali et al. reported that neuropeptide Y, which is released during sympathetic stimulation, is independently associated with concentric LVH in ESRD patients [5]. In a recent study, nocturnal haemodialysis normalizes the autonomic dysfunction in ESRD patients probably by decreasing the intermittent nocturnal hypoxaemia [6]. As Professor Zoccali has pointed out, it is important to pay more attention to the association of nocturnal hypoxaemia with autonomic dysfunction and LVH in order to reduce the cardiovascular complications in ESRD patients.
Conflict of interest statement. None declared.
Cardiovascular Division Toujinkai Hospital Kyoto Japan Email: tojinkai.hosp{at}dream.com
References
- Zoccali C, Mallamaci F, Tripepi G, Benedetto FA. Autonomic neuropathy is linked to nocturnal hypoxaemia and to concentric hypertrophy and remodelling in dialysis patients. Nephrol Dial Transplant 2001; 16: 70–77
[Abstract/Free Full Text] - Zoccali C, Benedetto AF, Mallamaci F et al. Left ventricular hypertrophy and nocturnal hypoxemia in hemodialysis patients. J Hypertens 2001; 19: 287–293[CrossRef][Medline]
- Cutler MJ, Swift NM, Keller DM, Wasmund WL, Smith ML. Hypoxia-mediated prolonged elevation of sympathetic nerve activity after periods of intermittent hypoxic apnea. J Appl Physiol 2004; 96: 754–761
[Abstract/Free Full Text] - Cutler MJ, Swift NM, Keller DM, Wasmund WL, Burk JR, Smith ML. Periods of intermittent hypoxic apnea can alter chemoreflex control of sympathetic nerve activity in humans. Am J Physiol Heart Circ Physiol 2004; 287: H2054–H2060
[Abstract/Free Full Text] - Zoccali C, Mallamaci F, Tripepi G et al. Neuropeptide Y, left ventricular mass and function in patients with end stage renal disease. J Hypertens 2003; 21: 1355–1362[CrossRef][Web of Science][Medline]
- Chan CT, Hanly P, Gabor J, Picton P, Pierratos A, Floras JS. Impact of nocturnal hemodialysis on the variability of heart rate and duration of hypoxemia during sleep. Kidney Int 2004; 65: 661–665[CrossRef][Web of Science][Medline]
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