Association between left ventricular mechanics and heart rate variability in untreated hypertensive patients

Ambulatory blood pressure variability in prediction of target organ injury: the SHIP AHOY study

BACKGROUND

Ambulatory hypertension is associated with elevated left ventricular mass index (LVMI), cardiac dysfunction, and increased arterial stiffness in adolescents. Whether the addition of measures of BP variability improves the prediction of subclinical cardiovascular target organ damage (TOD) over mean BP measures is not known.

METHODS

We assessed clinic and ambulatory BP (ABP), anthropometrics, and TOD in 397 adolescents. ABP means standard deviation (SD), BP, and heart rate (HR) dipping were calculated; coefficients of variability (CV) were calculated (SD/mean) to assess ABP variabilities. Measures of TOD included LVMI, left ventricular hypertrophy (LVH), LV systolic shortening, LV diastolic function (e'/a'), and pulse wave velocity. General linear models were used to determine if increased ABP variability measures were significant determinants of TOD in models containing mean ABP percentiles, age, sex, race/ethnicity, BMI z-score, and HR.

RESULTS

Mean participant age was 15.6 ± 1.7 years (63% white, 59% male) with mean casual BP 122.6/71.6 mmHg ±12.4/10.5, and mean awake systolic ABP 124.2/72.0 ± 11.3/7.7 mmHg. In linear models, increased awake CV-DBP and HR dipping were significant determinants of LVMI. CV-HR was an independent determinant of diastolic (e'/a') but not systolic dysfunction. Using logistic regression, the combination of awake and asleep diastolic ABP variability and awake systolic ABP percentile improved the prediction of LVH.

CONCLUSIONS

Consideration of ABP variability in addition to ABP percentile may aid in identifying adolescents at risk for LVH.

Relationship between heart rate variability and echocardiography indices of cardiac function in healthy individuals

PURPOSE

This study evaluated the relationship between HRV and echocardiography indices of cardiac function.

METHODS

Healthy individuals (N = 30) aged 33 ± 10 years old, underwent short-term resting HRV assessment and transthoracic echocardiography with speckle tracking analysis. Time domain - (i.e. R-R interval, root mean square of successive RR interval difference (RMSSD), standard deviation of normal RR intervals (SDNN) and frequency domain-measures of HRV (i.e. high-frequency power (HF), low-frequency power (LF), high-frequency normalised (HFnorm) and low-frequency normalised (LFnorm)). Echocardiography indices of cardiac function included; Left ventricular ejection fraction (LVEF), left- and right-ventricular global longitudinal strain (LV-GLS, and RV GLS), left atrial strain: left atrial reservoir (LAres), left atrial conduit (LAcon) and left atrial contraction (LACT).

RESULTS

The mean values for HRV time-domain measures were: R-R (991 ± 176 ms), SDNN (50.9 ± 21.5 ms), and RMSSD (46.8 ± 29.4 ms); and frequency-domain: LF (727 ± 606 ms2), HF (415 ± 35 ms2), LFnorm (56 ± 19.4) and HFnorm (36.5 ± 18.8). Mean values for indices of cardiac function were LVEF (59.9% ± 2.8%), LV-GLS (19.2% ± 1.4%), RV-GLS (21.7% ± 2.7%), LAres (36.8% ± 6.99%), LAcon (26.2% ± 6.95%) and LACT (12.3% ± 3.56%). There was a significant negative relationship between HF and LV-GLS (r = -0.47, p = 0.01) and RMSSD and LVEF (r = -0.39, p = 0.03) respectively.

CONCLUSION

Heart rate variability measures such as high frequency power and RMSSD are associated with left ventricle systolic function in healthy individuals.

The Effect of Yoga Nidra Intervention on Blood Pressure and Heart Rate Variability Among Hypertensive Adults: A Single-arm Intervention Trial

Background Hypertension [blood pressure (BP) >130/80 mmHg] contributes significantly to cardiovascular morbidity and mortality. Lifestyle modifications, including mindfulness-based practices like Yoga, meditation, and relaxation techniques, have emerged as promising adjuncts to pharmacotherapy. This study aimed to explore the acute effects of Yoga Nidra (YN) on BP in essential hypertension and the potential mechanisms of the effect of YN on BP, in the form of changes in heart rate variability (HRV) components. Methods A total of 32 hypertensive individuals (mean age: 43 ±0.54 years; 22 males, 10 females) were enrolled at the Lifestyle Disease Clinic. Patients were provided regular consultation and pharmacotherapy. BP and HRV were assessed before and after a 16-minute YN session. HRV parameters included time and frequency domain measures. Statistical analysis included linear regression to study the relationship of components of HRV with those of the changes in BP. Results Following YN intervention, there was a significant reduction in both systolic BP (SBP) (7 mmHg) and diastolic BP (DBP) (6 mmHg). HRV analysis revealed significant increases. Regression analysis showed changes in SBP having significant coefficients. Conclusions A single session of YN reduced the systolic and diastolic BP and increased HRV parameters. Regression analyses showed that the reduction in BP can be explained by an increase in HRV parameters. Thus, this study demonstrates the positive effect of YN as an intervention for essential hypertension and also the potential mechanisms behind it, which can be explained by the Neurovisceral Integration Model.

Associations between Heart Rate Variability Parameters and Hemodynamic Profiles in Patients with Primary Arterial Hypertension, Including Antihypertensive Treatment Effects

Background: Autonomic nervous system (ANS) dysfunction is an important factor in the development and progression of arterial hypertension (AH) and may produce adverse hemodynamic sequelae. ANS function can be evaluated by analyzing heart rate variability (HRV). The purpose of this study was to assess the possible correlation between HRV and the hemodynamic profile of AH patients, including antihypertensive treatment effects after 12 months. Methods: The study was conducted on 144 patients with uncomplicated AH. The hemodynamic profile was assessed via echocardiography and impedance cardiography (ICG). The analyzed HRV parameters included SDNN, rMSSD, pNN50, low frequency (LF, 0.05–0.15 Hz), high frequency (HF, 0.15–0.4 Hz), total power (TP, the variance of all NN intervals), and the day, night, and 24-h low-to-high frequency ratios (LF/HF). Results: Analysis showed various correlations of HRV parameters both with arterial blood pressure and with the hemodynamic profile assessed via echocardiography and ICG. The HRV parameters of increased ANS activity showed a correlation with improved left ventricle function (LV) and lower LV afterload. Conclusions: Effective antihypertensive treatment demonstrated beneficial effects on both the ANS balance and the hemodynamic profile.

Heart Rate Variability and Prognosis in Hemodialysis Patients: A Meta-Analysis

BACKGROUND

Heart rate variability (HRV) means the variation in time of beat-to-beat interval. Lower HRV has been shown to be related with death and cardiovascular events in previous studies. In the last few years, the number of patients with ESRD has increased steadily. Maintenance hemodialysis is the most prevalent renal replacement therapy in patients with ESRD. This study aims to investigate if decreased HRV is an independent predictor of mortality in maintenance hemodialysis patients.

METHODS

Pubmed/Medline, EMBASE, Ovid, the Web of Science, and the Cochrane Central Register of Controlled Trials databases were searched up to October 1, 2019, for full-text articles in English. Cohort studies reporting the association between HRV and prognosis in hemodialysis patients were selected. Data extraction was performed by 2 reviewers independently, with adjudication by a third reviewer. Extracted data included the study characteristics, HRV measurement and research outcomes. Hazard ratios (HRs) and 95% confidence interval (CI) were pooled in a random-effects model for outcomes of all-cause and cardiovascular mortality. Heterogeneity assessment, subgroup analyses, and sensitivity analysis were conducted.

RESULTS

A total of 7 studies were eligible. HRV metrics consist of SDNN, SDANN, RMSSD, pNN50, HRVTI, ULF, VLF, LF, HF, LF/HF ratio, HRT, DC, and scaling exponents α1 and α2. Decreased HRV was associated with higher all-cause mortality (HR: 1.63, 95% CI: 1.11-2.39, p = 0.014) and cardiovascular mortality (HR: 1.07, 95% CI: 1.00-1.15, p = 0.045). Among the different HRV metrics, decreased SDANN (p < 0.001) and decreased LF/HF ratio (p = 0.001) were identified as predictors of all-cause death. Decreased SDNN, SDANN, and LF/HF ratio were identified as predictors of cardiovascular death (p = 0.004, p = 0.001, and p = 0.002).

CONCLUSIONS

Decreased HRV is associated with higher risk of all-cause and cardiovascular death in the hemodialysis population. Decreased SDANN and LF/HF were identified as predictors of both all-cause and cardiovascular mortality, while the utility of other HRV metrics requires further investigation. The protocol for this study was registered with PROSPERO (CRD42019141886).

A review of current trends in three-dimensional analysis of left ventricular myocardial strain

Three-dimensional (3D) left ventricular (LV) myocardial strain measurements using transthoracic 3D echocardiography speckle tracking analysis have several advantages over two-dimensional (2D) LV strain measurements, because 3D strain values are derived from the entire LV myocardium, yielding more accurate estimates of global and regional LV function. In this review article, we summarize the current status of 3D LV myocardial strain. Specifically, we describe how 3D LV strain analysis is performed. Next, we compare characteristics of 2D and 3D strain, and we explain validation of 3D strain measurements, feasibility and measurement differences between 2D and 3D strain, reference values of 3D strain, and its applications in several clinical scenarios. In some parts of this review, we used a meta-analysis to draw reliable conclusions. We also describe the added value of 3D over 2D strain in several specific pathologies and prognoses. Finally, we discuss novel techniques using 3D strain and suggest its future directions.

The Effect of Antihypertensive Therapy on Left Ventricular Longitudinal Strain: Missing Part of the Puzzle

There is no consensus regarding the benefit of antihypertensive therapy on left ventricular structure and function. The most of studies investigated the effect of therapy on left ventricular hypertrophy, less studies were focused on left ventricular diastolic dysfunction and the minority on left ventricular mechanics. The majority of investigations showed positive effect of antihypertensive therapy on regression of left ventricular remodeling. Nevertheless, it is very difficult to distinguish the effect of antihypertensive medication from the effect of blood pressure reduction on left ventricular improvement. The other important issue in these studies is difficulty to distinguish the effect of left ventricular hypertrophy regression from the effect of antihypertensive medications on left ventricular diastolic function and mechanics. The novel findings suggest that the cascade of left ventricular remodeling in hypertensive heart disease begins with mechanical changes, continuous with diastolic dysfunction, and ends with left ventricular hypertrophy. This is very important paradigm because it enables early and timely diagnosis of subclinical left ventricular damage in hypertensive patients and should provide rapid detection of left ventricular function improvement during antihypertensive therapy.

Autonomic Neuromodulation Acutely Ameliorates Left Ventricular Strain in Humans

Low-level transcutaneous vagus nerve stimulation at the tragus (LLTS) is anti-adrenergic. We aimed to evaluate the acute effects of LLTS on left ventricular (LV) function and autonomic tone. Patients with diastolic dysfunction and preserved LV ejection fraction were enrolled in a prospective, randomized, double-blind, 2 × 2 cross-over study. Patients received two separate, 1-h sessions, at least 1 day apart, of active LLTS (20 Hz, 1 mA below the discomfort threshold) and sham stimulation. Echocardiography was performed after LLTS or sham stimulation to assess cardiac function. A 5-min ECG was performed to assess heart rate variability (HRV). Twenty-four patients were enrolled. LV global longitudinal strain improved by 1.8 ± 0.9% during active LLTS compared to sham stimulation (p = 0.001). Relative to baseline, HRV frequency domain components (low frequency, high frequency, and their ratio) were favorably altered after LLTS compared to sham stimulation (all p < 0.05). We concluded that LLTS acutely ameliorates cardiac mechanics by modulating the autonomic tone. Trial registration: NCT02983448.