Associations of parathyroid hormone levels and mineral parameters with heart rate variability in patients with end-stage renal disease

Effects of parathyroidectomy on plasma PTH fragments and heart rate variability in stage 5 chronic kidney disease patients

INTRODUCTION

Circulating intact parathyroid hormone (iPTH) levels include full-length (1-84) PTH and long C-PTH fragments, but primarily (7-84) PTH, which have been reported to have antagonistic effects on the bones and kidneys. However, their effects on the cardiovascular system remain unclear. In this study, the relationships between the plasma PTH fragments levels and heart rate variability (HRV) in stage 5 chronic kidney disease (CKD5) patients are explored. Furthermore, the effects of parathyroidectomy (PTX) on the above indices are investigated.

METHODS

In this cross-sectional study, 164 healthy controls and 354 CKD5 patients, including 208 secondary hyperparathyroidism (SHPT) subgroup with PTX, were enrolled. Circulating (7-84) PTH levels were calculated by subtracting plasma (1-84) PTH levels from iPTH levels. The HRV parameters were measured using a 24-hour Holter.

RESULTS

The baseline levels of plasma iPTH, (1-84) PTH, and (7-84) PTH in the CKD5 patients were 930.40 (160.65, 1792.50) pg/mL, 448.60 (99.62, 850.45) pg/mL, and 468.20 (54.22, 922.55) pg/mL, respectively. In the CKD5 patients, plasma (1-84) PTH levels were independently correlated with the standard deviation of the normal-to-normal R-R intervals (SDNN) and the standard deviation of the five-minute average of the normal R-R intervals (SDANN). With a median follow up time of 6.50 months after PTX in the SHPT patients (n = 30), improved SDNN and SDANN markers were related with decreased (1-84) PTH levels. Furthermore, an improved SDNN was related with decreased (7-84) PTH levels.

CONCLUSIONS

The CKD5 patients' baseline (1-84) PTH levels were correlated with the SDNN and SDANN. After PTX, an improved SDNN was related with decreased (1-84) PTH and (7-84) PTH levels, while improved SDANN was related with decreased (1-84) PTH levels. No antagonistic effects of (1-84) PTH and (7-84) PTH on HRV were found in the CKD5 patients.

Cardiovascular autonomic nervous system dysfunction in chronic kidney disease and end-stage kidney disease: disruption of the complementary forces

PURPOSE OF REVIEW

Several nontraditional risk factors have been the focus of research in an attempt to understand the disproportionately high cardiovascular morbidity and mortality in chronic kidney disease (CKD) and end-stage kidney disease (ESKD) populations. One such category of risk factors is cardiovascular autonomic dysfunction. Its true prevalence in the CKD/ESKD population is unknown but existing evidence suggests it is common. Due to lack of standardized diagnostic and treatment options, this condition remains undiagnosed and untreated in many patients. In this review, we discuss current evidence pointing toward the role of autonomic nervous system (ANS) dysfunction in CKD, building off of crucial historical evidence and thereby highlighting the areas in need for future research interest.

RECENT FINDINGS

There are several key mediators and pathways leading to cardiovascular autonomic dysfunction in CKD and ESKD. We review studies exploring the mechanisms involved and discuss the current measurement tools and indices to evaluate the ANS and their pitfalls. There is a strong line of evidence establishing the temporal sequence of worsening autonomic function and kidney function and vice versa. Evidence linking ANS dysfunction and arrhythmia, sudden cardiac death, intradialytic hypotension, heart failure and hypertension are discussed.

SUMMARY

There is a need for early recognition and referral of CKD and ESKD patients suspected of cardiovascular ANS dysfunction to prevent the downstream effects described in this review.There are many unknowns in this area and a clear need for further research.

Improved cognitive function after kidney transplantation compared to hemodialysis

End-stage renal disease is associated with chronic stress that in turn may result in endocrine changes, affect cognitive, and physical capacities and increase the risk for cardiovascular events. The objective of this study was to evaluate and characterize possible stress parameters and compare cognitive function in those patients. Physiological and biochemical stress parameters as well as cognitive function were assessed in 17 hemodialysis and 18 renal transplant patients and both groups were compared. Serum cortisol and interleukin-6 levels were elevated in both groups but showed no significant difference. Cholesterol and low-density lipoprotein levels were significantly higher in patients following renal transplantation. While heart rate variability was comparable in both groups, most cognitive tests showed better results in renal transplant patients. We showed that: (1) cognitive function may improve following renal transplantation; (2) standard biochemical stress parameters are not useful to discriminate stress in patients with chronic kidney disease; and (3) heart rate variability is unaltered in this setting.

Nondipping heart rate and associated factors in patients with chronic kidney disease

BACKGROUND

Nondipping heart rate (NHR) is a condition reported to be associated with cardiovascular events and cardiovascular mortality recently. We aimed to search whether there is difference among hypertensive patients with and without chronic kidney disease (CKD) in terms of NHR pattern and the factors associated with NHR in patients with CKD.

METHODS

The study included 133 hypertensive patients with normal kidney functions, 97 hypertensive patients with predialysis CKD, and 31 hypertensive hemodialysis patients. Heart rate, blood pressure and pulse wave velocity (PWV) were measured by 24-h ambulatory blood pressure monitorization. NHR was defined as a decrease of less than 10% at night mean heart rate when compared with daytime values.

RESULTS

NHR pattern was established as 26.3% in non-CKD hypertensive group, 43.3% in predialysis group and 77.4% in dialysis group. Among patients with CKD, when NHR group was compared with dipper heart rate group, it was seen that they were at older age, there were higher prevalence of diabetes mellitus and more female sex, and while the value of urea, creatinine, phosphorus, intact parathyroid hormone, and PWV were significantly higher, the value of hemoglobin, albumin and calcium were significantly lower. By multivariate analysis, hemoglobin [odds ratio (OR) 0.661; 95% CI 0.541-0.806; p < 0.001] and PWV (OR 1.433; 95% CI 1.107-1.853; p = 0.006) were established as independent determinants of NHR pattern.

CONCLUSIONS

NHR pattern is significantly more frequently seen in hypertensive CKD patients than in hypertensive patients with non-CKD. Anemia and increased arterial stiffness are seen independently associated with NHR in CKD patients.

Vitamin D, parathyroid hormone and cardiovascular risk: the good, the bad and the ugly

25-Hydroxyvitamin D insufficiency and increased cardiovascular risk (CVR) association is still debated. The vitamin D (VitD)-dependent parathyroid hormone (PTH) is considered as the possible actuator of VitD effects on CVR. To investigate the association of CVR, PTH and VitD, we carried out blood pressure measurements and blood samples and collected information on dietary habits, anamnestic, clinical and metabolic data of 451 participants in the Salerno area (Southern Italy) during the World Hypertension Day (17 May). CVR was calculated according to the Framingham CVR charts. The overall population mean age was 51.6 ± 0.7 years, and female sex was slightly prevalent (55%). VitD deficiency (<20 ng/ml) was most frequent (59.7%). In this population, VitD and CVR did not correlate. VitD and PTH inversely correlated (r = −0.265, P < 0.001) as expected. PTH was in direct correlation (r = 0.225, P < 0.001) with CVR. Elevated PTH (75 percentile; ≥49.5 pg/ml) levels identify a population with higher CVR (11.8 ± 0.5 vs. 8.5 ± 0.3, P < 0.001). In a multivariate analysis, both age and PTH correlate to CVR, but not VitD. In conclusion, VitD does not directly affect CVR in the overall population. Rather, increased PTH might be a better predictor of CVR.

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.