Circadian Variation of Death in Hemodialysis Patients

Circadian aspects of mortality in hospitalized patients: A retrospective observation from a large cohort

AIM

This study aimed to describe the circadian characteristics of hospitalized mortality in order to provide nursing guidance for preventing in-hospital mortality.

DESIGN

A retrospective analysis on inpatient information was implemented.

METHODS

Harmonic Analysis of Time Series was applied to quantify the periodic structure of the frequency of the occurrence of death.

RESULTS

A total of 3300 cases were included in the present study (male, 63.4% and median age 73 years), including 1540 (46.7%) ICU patients. Incidence of overall hospitalized death exhibited a circadian pattern, presenting peaks from 07:00 to 12:00 and 15:00 to 20:00 P.M., with 21.5% and 13.1% increase above the average at those peak points, respectively. Similarly, the incidence of sudden cardiac death (SCD) showed peaks between 06:00-12:00 and 15:00-20:00, with a 34.7% and 28.0% increase above the average at peak time, respectively. The distribution of death incidence revealed no statistical difference between SCD and non-SCD (p = 0.525).

Therapeutic Hypothermia Reduces Peritoneal Dialysis Induced Myocardial Blood Flow Heterogeneity and Arrhythmia

Background: Moderate therapeutic hypothermia (TH) is a well-recognized cardio-protective strategy. The instillation of fluid into the peritoneum provides an opportunity to deliver moderate hypothermia as primary prevention against cardiovascular events. We aimed to to investigate both cardiac perfusion consequences (overall blood flow and detailed assessment of perfusion heterogeneity) and subsequently simulate the associated arrhythmic risk for patients undergoing peritoneal dialysis (PD) induced TH. Methods: Patients underwent high resolution myocardial perfusion scanning using high resolution 256 slice CT scanning, at rest and with adenosine stress. The first visit using the patient's usual PD regimen, on the second visit the same regime was utilized but with cooled peritoneal dialysate at 32°C. Myocardial blood flow (MBF) was quantified from generated perfusion maps, reconstructed in 3D. MBF heterogeneity was assessed by fractal dimension (FD) measurement on the 3D left ventricular reconstruction. Arrhythmogenicity was quantified from a sophisticated computational simulation using a multi-scale human 3D ventricle wedge electrophysiological computational model. Results: We studied 7 PD patients, mean age of 60 ± 7 and mean vintage dialysis of 23.6 ± 17.6 months. There were no significant different in overall segmental MBF between normothermic condition (NT) and TH. MBF heterogeneity was significantly decreased (-14%, p = 0.03) at rest and after stress (-14%, p = 0.03) when cooling was applied. Computational simulation showed that TH allowed a normalization of action potential, QT duration and T wave. Conclusion: TH-PD results in moderate hypothermia leading to a reduction in perfusion heterogeneity and simulated risk of non-terminating malignant ventricular arrhythmias.

Parathyroidectomy Is Associated with Reversed Nondipping Heart Rate That Impacts Mortality in Chronic Kidney Disease Patients

OBJECTIVE

Nondipping heart rate (HR), defined as a night/day HR ratio >0.90, has been associated with increased mortality in epidemiologic studies. However, its prognostic value in stage 5 chronic kidney disease (CKD5) patients and the effects of parathyroidectomy (PTX) on nondipping HR remain unknown.

METHODS

This case-control study of 162 healthy controls and 502 CKD5 patients was performed between 2011 and 2018, in which CKD5 patients were further divided into non-PTX (n = 186) and severe secondary hyperparathyroidism (SHPT) with PTX (n = 316) subgroups. Each participant underwent 24-hour Holter monitoring for HR ratio. Mortality was followed up in CKD5 patients (median time: 46.0 months).

RESULTS

The HR ratio in CKD5 patients was higher than in controls (0.92 ± 0.08 vs 0.81 ± 0.08, P <.001), associated with a 44% increase in mortality risk per 0.1 increment (hazard ratio, 1.44; 95% CI: 1.02-2.03; P =.04), and was positively related to serum intact parathyroid hormone levels (P <.001). PTX reversed nondipping HR in SHPT patients (n = 50, median time: 6.3 months, P <.001). Survival probabilities for PTX (n = 294) were better than non-PTX (n = 47) (hazard ratio, 0.31; 95% CI: 0.14-0.67; P <.01) in SHPT patients (serum intact parathyroid hormone >500.0 pg/mL).

CONCLUSION

CKD5 patients displayed a nondipping HR pattern, which is a prognostic marker of all-cause mortality. PTX for SHPT patients was associated with a reversal in nondipping HR ratio, which may mediate a better outcome.

Cycles, Arrows and Turbulence: Time Patterns in Renal Disease, a Path from Epidemiology to Personalized Medicine?

Patients with end-stage renal disease (ESRD) experience unique patterns in their lifetime, such as the start of dialysis and renal transplantation. In addition, there is also an intricate link between ESRD and biological time patterns. In terms of cyclic patterns, the circadian blood pressure (BP) rhythm can be flattened, contributing to allostatic load, whereas the circadian temperature rhythm is related to the decline in BP during hemodialysis (HD). Seasonal variations in BP and interdialytic-weight gain have been observed in ESRD patients in addition to a profound relative increase in mortality during the winter period. Moreover, nonphysiological treatment patters are imposed in HD patients, leading to an excess mortality at the end of the long interdialytic interval. Recently, new evidence has emerged on the prognostic impact of trajectories of common clinical and laboratory parameters such as BP, body temperature, and serum albumin, in addition to single point in time measurements. Backward analysis of changes in cardiovascular, nutritional, and inflammatory parameters before the occurrence as hospitalization or death has shown that changes may already occur within months to even 1-2 years before the event, possibly providing a window of opportunity for earlier interventions. Disturbances in physiological variability, such as in heart rate, characterized by a loss of fractal patterns, are associated with increased mortality. In addition, an increase in random variability in different parameters such as BP and sodium is also associated with adverse outcomes. Novel techniques, based on time-dependent analysis of variability and trends and interactions of multiple physiological and laboratory parameters, for which machine-learning -approaches may be necessary, are likely of help to the clinician in the future. However, upcoming research should also evaluate whether dynamic patterns observed in large epidemiological studies have relevance for the individual risk profile of the patient.

Effect of Sympatholytic Therapy on Circadian Cardiac Autonomic Activity in Non-Diabetic Chronic Kidney Disease

Although beta-blockade itself is not a first choice for chronic kidney disease (CKD) patients, alpha-beta-blockers (ABB) do improve their prognoses. This study's aim was to evaluate the effect of beta-selective-blockers (BSB) and ABB on circadian cardiac autonomic activity in CKD patients.The study consisted of 496 non-diabetic individuals who underwent 24-hour Holter monitoring (149 CKD patients and 347 controls without CKD). Using heart rate variability analysis, we evaluated the proportion of NN50 and the high-frequency component (reflecting parasympathetic activity), and low- to high-frequency ratio (reflecting sympathovagal balance). These indices were evaluated by regression analysis incorporating gender, age, related comorbidities, and medications. BSB increased vagal activity only in the day-time and not the night-time in controls. In CKD patients, BSB was significantly related to higher vagal activity throughout the day and with lower sympathovagal balance at night. The night sympathovagal balance of CKD patients taking ABB was significantly higher than that of CKD patients taking BSB, which was the only significant difference between the effects of BSB and ABB.The sympatholytic therapy effect is different depending on CKD presence and whether patients are treated with BSB or ABB. In CKD patients without severe heart failure, BSB could be associated with higher parasympathetic activity and lower sympathovagal balance compared to ABB.

Blood pressure and heart rate variability are linked with hyperphosphatemia in chronic kidney disease patients

Hyperphosphatemia is a common complication of chronic kidney disease (CKD) and is associated with cardiovascular disease (CVD), which has contributed to an increase in mortality of CKD patients. The onset of CVD often varies by time-of-day. Acute myocardial infarction or ventricular arrhythmia occurs most frequently during early morning. Blood pressure (BP) and heart rate circadian rhythms account for the diurnal variations in CVD. Preservation of normal circadian time structure from the cardiomyocyte level to the whole organ system is essential for cardiovascular health and CVD prevention. Independent risk factors, such as reduced heart rate variability (HRV) and increased BP variability (BPV), are particularly prevalent in patients with CKD. Analysis of HRV is an important clinical tool for characterizing cardiac autonomic status, and reduced HRV has prognostic significance for various types of CVD. Circadian BP rhythms are classified as extreme dipper, dipper, non-dipper or riser. It has been reported that nocturnal riser BP pattern contributes to cardiovascular threats. Previous studies have indicated that the circadian rhythm of serum phosphate in CKD patients is consistent with the general population, with the highest diurnal value observed in the early morning hours, followed by a progressive decrease to the lowest value of the day, which occurs around 11:00 am. Rhythm abnormalities have become the main therapeutic target for treating CVD in CKD patients. It has been reported that high levels of serum phosphate are associated with reduced HRV and increased BPV in CKD patients. However, the mechanisms related to interactions between hyperphosphatemia, HRV and BPV have not been fully elucidated. This review focuses on the evidence and discusses the potential mechanisms related to the effects of hyperphosphatemia on HRV and BPV.

Disrupted circadian rhythm in rats with nephrectomy-induced chronic kidney disease

AIMS

Our study investigated the role of circadian rhythm in the pathogenesis of sleep disturbance in patients with chronic kidney disease (CKD) based on an animal model.

MAIN METHODS

Sixteen Sprague-Dawley (SD) rats (eight from 5/6 nephrectomized CKD group and eight from control group) were used for electroencephalography (EEG) and electromyography (EMG) recording. Eight rats (four from CKD and four from control group) were sacrificed at six Zeitgeber time (ZT) points and determined the mRNA expression of clock genes, rPer1, rPer2 and rBMAL1b in the hypothalamus.

KEY FINDINGS

Our results demonstrated that both slow wave sleep (SWS) and rapid eye movement (REM) sleep were significantly increased in the ZT22-24 Zeitgeber time point of the dark period in the CKD rats when compared with those sleep architectures obtained from the control rats. The CKD-induced sleep disruptions were associated with significant upregulations of rPer1 (in ZT2, ZT6 and ZT14) and rPer2 mRNA expression (in ZT2 and ZT14) in the hypothalamus.

SIGNIFICANCE

Our study elucidated that the increases of SWS and REM sleep during ZT22-24 of the dark period in the CKD rats might be due to the enhancement of rPer1 and rPer2 clock genes in the hypothalamus, suggesting that disrupted circadian rhythm plays a role in the pathogenesis of sleep disturbance in patients with CKD.