Does transcatheter ventricular septal defect closure affect heart rate variability in children?

BACKGROUND

Heart rate variability (HRV) is a sign of the cardiac autonomic nervous system. Its evaluation in pediatric ventricular septal defect (VSD) cases before and after transcatheter closure contributes to an understanding of cardiac autonomic control.

METHODS

Nineteen children with VSDs treated with transcatheter closure and 18 healthy children were enrolled in this study. A 24-h Holter rhythm monitor was applied to all patients before VSD closure and to those in the control group. Holter rhythm monitoring was repeated at three months in the patient group. HRV parameters were measured using the Cardio Scan Premier 12® program. Frequency-domain (total power; very-low-frequency, low-frequency (LF), and high-frequency (HF) indices; and the LF/HF ratio) and time-domain (standard deviation of all RR intervals (SDNN), standard deviation of 5-min averages of RR intervals (SDANN), the SDNN index, percentage of the difference between adjacent RR intervals, and the square root of the mean of the sum of square differences between adjacent filtered RR intervals) parameters were assessed.

RESULTS

Before the procedure, SDNN, SDANN, and total power values were lower in the patient group than in the control group; other parameters were similar in the two groups. No significant difference in the SDNN, SDANN, or total power was detected between the patient and control groups in the third month, indicating that autonomic control of patients' hearts became normal during the third postoperative month. No correlation was detected between any hemodynamic parameters and any time-domain or frequency-domain parameters before closure.

CONCLUSION

This study showed that transcatheter closure of VSDs changed HRV parameters in pediatric patients.

In newly diagnosed hypertensive children, increased arterial stiffness and reduced heart rate variability were associated with a non-dipping blood pressure pattern

OBJECTIVES

This study was designed to investigate the differences in pulsatile hemodynamics, echocardiographic findings, 24-h Holter monitoring and heart rate variability parameters of dipper patterns in children with newly diagnosed essential hypertension.

METHODS

This study included 30 children with newly diagnosed essential hypertension and 30 healthy controls. The essential hypertension cohort was divided into dippers and non-dippers. Physical examinations, 24-hour ambulatory blood pressure monitoring, 24-h Holter monitoring, 24-h heart rate variability, conventional 2-dimensional and Doppler echocardiography, and tissue Doppler imaging were performed. Pulse wave analysis using an oscillometric monitor was conducted to measure augmentation index (AIx) and pulse wave velocity (PWV).

RESULTS

In patients with essential hypertension, left ventricular (LV) wall thickness and LV mass index were increased. There were no significant differences in LV mass index and LV wall thickness based on the dipping patterns. Time domain values and the standard deviation of all RR intervals (SDNN) were substantially lower in the essential hypertension group. SDNN values were considerably lower in the non-dipper group compared with the dipper group. In terms of frequency domain measures, low frequency measured in daytime values was much lower in the essential hypertension group compared with the control. The dipper patterns revealed that low frequency measured in nighttime values was also substantially lower in the non-dipper group. Pulse wave analysis and AIx values were notably higher in the essential hypertension patient group and those with non-dipper status.

CONCLUSION

SDNN values, which reflect parasympathetic activity, were markedly lower in children with hypertension and the non-dipper group than healthy controls and the dipper group, respectively. Also, parameters related to arterial stiffness, such as PWV and AIx values were significantly higher in children with hypertension and the non-dipper group.

Autonomic cardiovascular control and cardiac arrhythmia in two pregnant women with hypertrophic cardiomyopathy: Insights from ICD monitoring

In women with hypertrophic cardiomyopathy (HCM), pregnancy prompts major changes in hemodynamic and cardiac autonomic function that may precipitate heart failure (HF) or increase the risk of cardiac arrhythmia. We report the clinical follow-up of two patients with non-obstructive HCM implanted with a cardioverter defibrillator (ICD) allowing for continuous analysis of heart rate (HR), heart rate variability (HRV) and cardiac arrhythmia throughout the entire course of pregnancy. Both patients experienced increased HR and decreased HRV from the early stages of pregnancy, which persisted until delivery. Premature ventricular contractions (PVCs) and runs of non-sustained ventricular tachycardia (NSVT) reached a peak in the second and third trimesters, concurrent with sympathetic hyperactivity. In one patient with baseline NYHA class II HF symptoms, increased PVCs and NSVT were consistent with the deterioration of HF, supporting the decision to bring the delivery forward. While both patients experienced a persistent increase in sympathetic tone and ventricular ectopic activity, no life-threatening arrhythmias were documented. During pregnancy, patients with hypertrophic cardiomyopathy develop progressive neuroautonomic imbalance, prompting an increase in non-sustained ventricular arrhythmia. This enhanced arrhythmia burden warrants close follow-up and rhythm assessment during the third trimester, especially in women who have heart failure symptoms before pregnancy. Implantable cardioverter defibrillators provide a continuous analysis of heart rate variability and arrhythmia burden that supports therapeutic decision-making during follow-up.

Impact of malnutrition on cardiac autonomic modulation in children

OBJECTIVE

To compare the autonomic behavior between malnourished children and a control group using analysis of heart rate variability (HRV).

METHOD

Data were analyzed from 70 children who were divided into two groups: malnourished and eutrophic, according to the Z-score nutritional status for height and age. For analysis of HRV indices, heart rate was recorded beat to beat with the child in the supine position for 20min. The analysis of these indices was performed using linear methods, analyzed in the time and frequency domains. Student's t-test for unpaired data and the Mann-Whitney test were used to compare variables between groups, with a significance level of 5%.

RESULTS

A reduction in systolic and diastolic blood pressure and an increase in heart rate were found in malnourished children compared to eutrophic children. The HRV indices suggested that malnourished children present reductions in both sympathetic and parasympathetic autonomic nervous system activity. The SDNN, rMSSD, NN50, pNN50, SD1, SD2, TINN, LF (ms²), and HF (ms²) indices were lower in malnourished children.

CONCLUSION

Malnourished children present changes in cardiac autonomic modulation, characterized by reductions in both sympathetic and parasympathetic activity, as well as increased heart rate and decreased blood pressure.

Heart rate variability in myocardial infarction patients: effects of exercise training

Heart rate variability (HRV) is a simple and noninvasive measure that estimates cardiac autonomic modulation, mainly the parasympathetic contribution. Increased sympathetic and/or decreased parasympathetic nervous activity is seen in post-myocardial infarction (MI) patients. Consequently, these patients present reduced HRV, which has been associated with increased risk of adverse events and mortality. Exercise training, recommended as a complementary therapy for patients with cardiovascular disease, has shown numerous beneficial effects. The main aim of the present manuscript was to provide a critical review of studies investigating the effects of exercise training on cardiac autonomic modulation, through HRV, in MI patients and the possible mechanisms involved. Despite conflicting evidence, exercise training appears to be a useful therapeutic intervention to improve the unbalanced autonomic function of MI patients. Finally, the mechanisms involved are not yet well understood, but nitric oxide bioavailability and angiotensin II levels seem to play an important role.