Relationship between heart rate variability and left ventricular remodeling after reperfused first anterior wall acute myocardial infarction

Associations between respiratory arrhythmia and fundamental frequency of spontaneous crying in preterm and term infants at term-equivalent age

This study investigated whether lower vagal function in preterm infants is associated with increased fundamental frequency (F₀; frequency of vocal fold vibration) of their spontaneous cries. We assessed respiratory sinus arrhythmia (RSA) during quiet sleep as a measure of vagal function, and its relationship with the F₀ of spontaneous cries in healthy preterm and term infants at term‐equivalent age. The results showed that preterm infants have significantly lower RSA, and higher overall F₀ than term infants. Moreover, lower RSA was associated with higher overall F₀ in preterm infants, whereas higher RSA was positively associated with mean and maximum F₀, and a larger F₀ range in term infants. These results suggest that individual differences in vagal function may be associated with the F₀ of spontaneous cries via modulation of vocal fold tension in infants at an early developmental stage. © 2016 The Authors. Developmental Psychobiology Published by Wiley Periodicals, Inc. Dev Psychobiol 58:724–733, 2016.

Effects of progressive exercise during phase I cardiac rehabilitation on the heart rate variability of patients with acute myocardial infarction

PURPOSE

Heart rate variability (HRV) decreases after an acute myocardial infarction (AMI) due to changes in cardiac autonomic balance. The purpose of the present study, therefore, was to evaluate the effects of a progressive exercise protocol used in phase I cardiac rehabilitation on the HRV of patients with post-AMI.

MATERIAL AND METHODS

Thirty-seven patients who had been admitted to hospital with their first non-complicated AMI were studied. The treated group (TG, n=21, age=52±12 years) performed a 5-day programme of progressive exercise during phase I cardiac rehabilitation, while the control group (CG, n=16, age=54±11 years) performed only respiratory exercises. Instantaneous heart rate (HR) and RR interval were acquired by a HR monitor (Polar®S810i). HRV was analysed by frequency domain methods. Power spectral density was expressed as normalised units (nu) at low (LF) and high (HF) frequencies, and as LF/HF.

RESULTS

After 5 days of progressive exercise, the TG showed an increase in HFnu (35.9±19.5 to 65.19±25.4) and a decrease in LFnu and LF/HF (58.9±21.4 to 32.5±24.1; 3.12±4.0 to 1.0±1.5, respectively) in the resting position (p<0.05). No changes were observed in the CG.

CONCLUSIONS

A progressive physiotherapeutic exercise programme carried out during phase I cardiac rehabilitation, as supplement to clinical treatment increased vagal and decreased sympathetic cardiac modulation in patients with post-AMI.

Sympathetic overactivity in patients with left ventricular aneurysm in early period after anterior myocardial infarction: does sympathetic activity predict aneurysm formation?

Left ventricular aneurysm (LVA) is an important complication of acute transmural myocardial infarction (MI) that bears great clinical significance because of high mortality. Heart rate variability (HRV) analysis is extensively used to evaluate autonomic modulation of sinus node and to identify patients at risk for an increased cardiac mortality. In this study, the authors evaluated HRV in patients with LVA in the early period after acute anterior wall MI. They compared 18 patients (7 men, 11 women, with an average age of 56.1 +/-8.2 years) with LVA and 46 patients (34 men, 12 women, with an average age of 56.4 +/-5.9 years) without LVA. Mean heart rate, low frequency (LF) and low-frequency/high-frequency (LF/HF) ratio were significantly higher and standard deviation of normal-to-normal RR intervals (SDNN), root mean square of successive differences (RMSSD), number of NN intervals that differed by more than 50 ms from adjacent interval divided by the total number of all NN intervals (PNN50), and HF were lower in the patients with LVA. A SDNN <78 ms separated the patients with aneurysm from those without aneurysm with a sensitivity of 78%, specificity of 83%, positive predictive accuracy of 79%; a LF/HF ratio >2.4 with a sensitivity of 92%, specificity of 88%, and positive predictive accuracy of 92%. Single-vessel disease increased the left ventricular aneurysm formation by 5.1 fold, total left anterior descending artery (LAD) occlusion by 3.1 fold, mean heart rate >75 beats/minute by 2.3 fold, SDNN <78 ms by 7.9 fold, and LF/HF ratio >2.4 by 12.9 fold, but well-developed collaterals decreased the aneurysm formation by 4.4 fold. As a result, HRV analysis supplies parameters with high predictive value for LVA formation in the early period after acute anterior MI. The higher sympathetic activity and reduced heart rate variability may be associated with a higher incidence of complications such as ventricular arrhythmias and increased mortality in patients with LVA.

Influence of Angiotensin-Converting Enzyme I/D Gene Polymorphism on the Right Ventricular Myocardial Performance Index in Patients With a First Acute Anterior Myocardial Infarction

BACKGROUND

The genetic influence on the myocardial performance index is uncertain, so the aim of the present study was to determine the effects of polymorphism of the angiotensin-converting enzyme (ACE) gene on the right ventricular myocardial performance index (RVMPI) after a first acute anterior myocardial infarction (MI).

METHODS AND RESULTS

The subjects were 116 patients with a first acute anterior MI. Based on the polymorphism of the ACE gene, they were classified into 3 groups: deletion/deletion (DD) genotype (group 1, n=45), insertion/deletion (ID) genotype (group 2, n=58), insertion/insertion (II) genotype (group 3, n=13). Echocardiograms were used to determine the RVMPI, left ventricular myocardial performance index (LVMPI), tricuspid E/A, tricuspid deceleration time and the left ventricular diameter diastolic and diameter systolic (LVDd and LVDs). RVMPI and LVMPI were significantly higher in the ACE DD group. Tricuspid E/A, DT, LVDd and LVDs showed no differences among the 3 groups.

CONCLUSION

The ID polymorphism of the ACE gene may affect RVMPI and LVMPI after a first acute anterior MI.

Very low frequency power of heart rate variability is a powerful predictor of clinical prognosis in patients with congestive heart failure

BACKGROUND

The present study examined whether the very low frequency (VLF) power of heart rate variability (HRV) is predictive of clinical prognosis in patients with congestive heart failure (CHF).

METHOD AND RESULTS

The study recruited 54 consecutive CHF patients with emergency admission because of exacerbation of pulmonary congestion. Holter monitoring was performed after improvement of pulmonary congestion. The frequency components of HRV were calculated in the frequency domain (VLF, low frequency (LF), high frequency (HF), total power (TP) and the ratio of LF to HF power). The left ventricular ejection fraction was calculated, and plasma brain natriuretic peptide (BNP) and norepinephrine were also measured at discharge. Within a mean follow-up period of 19.8 +/- 11.7 months, 18 patients experienced cardiovascular events; 7 patients died and 11 patients required rehospitalization because of worsening of CHF. In univariate analysis, diabetes mellitus (DM), BNP and New York Heart Association (NYHA) functional class were significant as risk factors for cardiac events. VLF power, LF power and TP were the strong predictors for cardiac events in HRV. In multivariate analysis, VLF power predicted cardiac events independently of LF power, TP, DM, BNP and NYHA functional class (chi-square=6.24, p=0.01).

CONCLUSIONS

VLF power is an independent risk predictor in patients with CHF.

Relation Between Variability of Ventricular Response Intervals and Exercise Capacity in Patients With Non-Valvular Atrial Fibrillation

BACKGROUND

Reduced variability of the ventricular response interval (VRI) has been reported to predict adverse prognosis in patients with atrial fibrillation (AF). To examine whether it could be related also to the quality of the daily life of patients with AF, the relationships between VRI variability and exercise tolerance, one of the markers for quality of life, were determined in patients with persistent AF.

METHODS AND RESULTS

Thirty-one patients with idiopathic AF were included in the present study. Holter monitoring results and symptom-limited treadmill exercise testing were correlated in these patients without medications for the rate control of AF. The VRI variability, both the SD of the mean R-R interval (SDNN) and the SD of the 5-min mean R-R interval (SDANN), showed significant positive correlation with the exercise capacity (r=0.583, p=0.0004, and r=0.543, p=0.0013, respectively), whereas age, left ventricular ejection fraction and body mass index did not have any significant relationships. Multiple regression analysis revealed that increased SDNN was the only independent predictor of good exercise capacity during the treadmill exercise testing.

CONCLUSIONS

Increased VRI variability, independently of other clinical variables, can predict good exercise capacity in patients with idiopathic AF, thus being a new sensitive maker for quality of life in AF.