Evaluation of heart rate variability using 24-hour Holter electrocardiography in hypertensive patients

Heart Rate Recovery: Up to Date in Heart Failure-A Literature Review

The rising prevalence of cardiovascular disease underscores the growing significance of heart failure (HF). Pathophysiological insights into HF highlight the dysregulation of the autonomic nervous system (ANS), characterized by sympathetic overactivity and diminished vagal tone, impacting cardiovascular function. Heart rate recovery (HRR), a metric measuring the heart's ability to return to its baseline rate post-exertion, plays a crucial role in assessing cardiovascular health. Widely applied across various cardiovascular conditions including HF, coronary artery disease (CAD), and arterial hypertension (HTN), HRR quantifies the difference between peak and recovery heart rates. Given its association with elevated sympathetic tone and exercise, HRR provides valuable insights into the perspective of HF, beyond effort tolerance, reaching toward prognostic and mortality indicators. Incorporating HRR into cardiovascular evaluations enhances our understanding of autonomic regulation in HF, offering potential implications for prognostication and patient management. This review addresses the significance of HRR in HF assessment, analyzing recently conducted studies, and providing a foundation for further research and clinical application.

Heart rate variability between hormone phases of the menstrual and oral contraceptive pill cycles of young women

INTRODUCTION

The interplay between the sympathetic and parasympathetic branches of the autonomic nervous system contribute to adequate hemodynamic responses to stressors, reflected by the variation in intervals between heart beats, known as heart rate variability. The sex hormones estrogen and progesterone have been shown to affect autonomic function. The extent to which autonomic function may vary between different hormone phases of the natural menstrual cycle and how this relationship may differ in women taking oral contraceptives has yet to be fully elucidated.

PURPOSE

To investigate differences in heart rate variability between the early follicular and early luteal phases of the menstrual cycle in naturally menstruating women and in oral contraceptive pill users.

METHODS

Twenty-two young (22 ± 3 years), healthy women who were naturally menstruating or taking oral contraceptive pills participated in this study. Heart rate variability was measured at rest and during two sympathomimetic stressors: isometric handgrip exercise and cold pressor test.

RESULTS

The proportion of successive NN intervals that differ by more than 50 ms was higher in oral contraceptive pill users during the placebo pill phase. Absolute high-frequency power was higher in the naturally menstruating women during the early luteal phase, relative to the early follicular phase. Other indices of vagal modulation were not different at rest or during sympathetic activation between hormone phases or groups.

CONCLUSIONS

Vagal modulation may be increased in the early luteal menstrual cycle phase. Further,oral contraceptive use does not appear to adversely affect this modulation in young, healthy women.

Role of basal autonomic functions in patients with increased morning blood pressure surge

BACKGROUND

Morning blood pressure (BP) surge (MS) is associated with cardiovascular events. The autonomic nervous system plays an active role in the regulation of BP and its function can be evaluated by heart rate variability (HRV) analysis. This study aimed to evaluate autonomic nervous system functions in patients with increased MS.

METHODS

Patients who underwent ambulatory BP monitoring (ABPM) and 24-h rhythm Holter in our hospital during the same period between 2017 and 2022 were evaluated. HRV parameters were obtained from 24-h rhythm Holter recordings. MS values of the patients were calculated from ABPM records and patients were divided into four groups according to the MS quartiles. HRV parameters and other parameters were compared between the groups.

RESULTS

A total of 129 patients were included in the study. The mean age of the patients was 57.2 ± 18.2 years, and 63 (48.8%) were male. HF, the square root of the mean squared differences of successive normal-to-normal intervals (rMSSD), and the proportion of adjacent RR intervals differing by >50 ms in the 24-h recording (pNN50) were statistically significant between the groups ( P  = 0.039, P  = 0.013, P  = 0.011, respectively). In univariate regression analysis, low-frequency/high-frequency ratio was positively associated with MS and HF, SDNNi, rMSSD, and pNN50 were negatively associated ( β  = 0.207, P  = 0.019; β  = -0.272, P  = 0.002; β  = -0.201, P  = 0.022; β  = -0.265, P  = 0.002; β  = -0.278, P  = 0.001, respectively). Multiple linear regression analysis showed an independent association between HF, low-frequency/high-frequency ratio, rMSSD, pNN50, and MS ( β  = -0.247, P  = 0.005; β=0.206, P  = 0.017; β  = -0.209, P  = 0.005; β  = -0.227, P  = 0.008, respectively).

CONCLUSION

We found an independent association between HRV parameters associated with vagal tone and MS. The findings of our study suggest that the increased sympathetic activity detected in patients with high MS in previous studies may be due to a decrease in basal vagal tone.