Heart rate variability as a measure of autonomic nervous system function in anorexia nervosa.

BACKGROUND AND HYPOTHESIS: Alteration in sympathovagal balance may be a mechanism of increased cardiovascular mortality and sudden death of patients with anorexia nervosa. This study was undertaken to characterize cardiac autonomic control in patients with anorexia nervosa by means of heart rate variability analysis. METHODS: Heart period variability by 24-h Holter recording was evaluated in 13 young women with anorexia nervosa, 10 constitutionally thin women, and 10 women of normal weight. RESULTS: High-frequency power, a measure of parasympathetic modulation of heart rate, and all-time domain measures of heart rate variability were higher in patients with anorexia nervosa than in thin women and in those of normal weight. Thin women showed lower values of total power and of most components of power spectrum. CONCLUSIONS: Our data demonstrate an increased vagal tone in young women with anorexia nervosa. The marked increase in parasympathetic activity, not in response to an increase in sympathetic activity, could be detrimental and may contribute to the higher cardiovascular mortality of these patients.

Power spectral analysis of heart period variability in hypertensive patients with left ventricular hypertrophy.

This study aimed to characterize sympathovagal balance by heart period power spectrum analysis in hypertensive patients with echocardiographic evidence of left ventricular hypertrophy. Twenty ambulatory patients (11 men and 9 women), aged 50 +/- 10 years, with established essential hypertension and echocardiographic left ventricular hypertrophy, performed 24-h blood pressure monitoring and electrocardiogram Holter recording on 2 consecutive days. Twenty age- and sex-matched normal subjects comprised the control group. Power spectrum analysis, performed using the fast Fourier transform algorithm, demonstrated lower values of low and high frequency power in hypertensives than in controls, while ultralow and very low frequency power were similar in the two groups. Very low frequency, low frequency, and high frequency power increased during the night in both groups, showing a similar circadian pattern. We found a direct correlation between daytime systolic (r = 0.51; P < .05) and diastolic (r = 0.52; P < .05) blood pressure and left ventricular mass index. Moreover, negative correlations were found between left ventricular mass index and low frequency (r = -0.47; P < .05) and high frequency power (r = -0.47; P < .05). There was a direct correlation between nighttime decrease in systolic blood pressure and nighttime increase in high frequency power (r = 0.45; P < .05). As 24-h low frequency and high frequency power, obtained using the Fourier transform algorithm, both reflect the parasympathetic modulation of heart rate, our results demonstrate that hypertensive patients with left ventricular hypertrophy are characterized by a sympathovagal imbalance with a reduction of vagal tone that is more evident with increasing severity of hypertension.

Influence of reversible segmental left ventricular dysfunction on heart period variability in patients with one-vessel coronary artery disease.

OBJECTIVES: This study evaluated the relation between reversible segmental left ventricular dysfunction and frequency domain measures of heart period variability in patients with coronary artery disease. BACKGROUND: Heart period variability is frequently reduced in patients with coronary artery disease. However, the mechanisms of this reduction are still unclear. METHODS: Echocardiographic left ventricular wall motion and frequency domain measures of heart period variability were evaluated in 32 patients with one-vessel coronary artery disease before and 16 to 24 days after successful percutaneous transluminal coronary angioplasty. Of these, 12 patients (Group A) had normal and 20 patients (Group B) had abnormal regional wall motion. A control group of 15 healthy subjects (Group C) underwent 24-h Holter recording twice at 2-week intervals to check for spontaneous variations. RESULTS: At baseline, low and high frequency power were lower in Group B than in Groups A and C, whereas no difference was detectable in ultra low and very low frequency and total power. After coronary angioplasty, regional wall motion and frequency domain measures of heart period variability were unchanged in Group A. In Group B the mean (+/- SD) summed segment score improved from 17.1 +/- 3.6 to 12.8 +/- 2.0 (p < 0.01), and mean low and high frequency power (logarithmic units) increased from 6.14 +/- 0.23 to 6.35 +/- 0.34 (p < 0.01) and from 5.43 +/- 0.32 to 5.68 +/- 0.52 (p < 0.01), respectively. Furthermore, low and high frequency power, lower at baseline in Group B than in the other two groups, were comparable in the three groups after coronary angioplasty. CONCLUSIONS: This study demonstrates that segmental left ventricular dysfunction is involved in determining sympathovagal imbalance in patients with one-vessel coronary artery disease; the reversal of left ventricular dysfunction by successful coronary angioplasty improves the heart period power spectrum. Thus, alterations in cardiac geometry influence the discharge of afferent sympathetic mechanoreceptors, contributing to the derangement in autonomic control of heart rate.

[Effects of coronary angioplasty on heart rate variability explored in the domain of time and frequency in patients with one-vessel coronary disease]. / Effetti dell'angioplastica coronarica sulla variabilità della frequenza cardiaca esplorata nel dominio del tempo e della frequenza in pazienti con coronaropatia monovasale.

BACKGROUND: Heart period variability is frequently reduced in patients with coronary artery disease. Although the mechanism for this reduction is still unclear, it seems to reflect alterations in cardiac autonomic control. In this study we have evaluated the relation between reversible segmental left ventricular dysfunction and time and frequency domain measures of heart period variability in patients with coronary artery disease. METHODS AND RESULTS: Echocardiographic segmental left ventricular wall motion and time and frequency domain measures of heart period variability were evaluated in 32 patients with one-vessel coronary artery disease before and 16-24 days after successful percutaneous transluminal coronary angioplasty (PTCA). At baseline examination 12 patients (Group A) had normal and 20 (Group B) abnormal regional wall motion. Prevalence of previous myocardial infarction was higher and mean angiographic ejection fraction lower in Group B than in Group A. At baseline, time domain measures were comparable between the 2 groups, while low frequency (LF) and high frequency (HF) power were lower in Group B than in Group A. After PTCA, in Group A regional wall motion and time and frequency domain measures of heart period variability were unchanged. In Group B summed segment score improved from 17.1 +/- 3.6 to 12.8 +/- 2.0 (p < 0.01) and a significant increase occurred in standard deviation of the average normal RR (NN) intervals for all 5-minute segments of a 24-hour recording (SDNN index), in root mean square successive difference (r-MSSD) and in the percentage of differences between adjacent NN intervals > 50 msec (pNN50). In this group also LF and HF power (logarithmic units) increased from 6.14 +/- 0.23 to 6.35 +/- 0.34 (p < 0.01) and from 5.43 +/- 0.32 to 5.68 +/- 0.52 (p < 0.01) respectively. There was no correlation between measures of heart period variability, summed segment score, and left ventricular ejection fraction. CONCLUSIONS: This study demonstrates that segmental left ventricular dysfunction is involved in determining sympathovagal imbalance in patients with one-vessel coronary artery disease; the reversal of left ventricular dysfunction by successful PTCA improves heart period variability. These findings support the hypothesis that alterations in cardiac geometry may influence the discharge of afferent sympathetic mechanoreceptors, thus contributing to the derangement in autonomic control of heart rate.

Effects of converting enzyme inhibition on heart period variability in patients with acute myocardial infarction.

BACKGROUND: Heart period variability provides useful prognostic information on autonomic cardiac control, and a strong association has been demonstrated after myocardial infarction (MI) between cardiac mortality, sudden death, and reduced total power, ultralow-frequency (ULF) power, and very-low-frequency (VLF) power. Converting enzyme inhibitors are widely used in MI patients, but their influence on heart period variability remains to be defined. METHODS AND RESULTS: Time- and frequency-domain measures of heart period variability were calculated from 24-hour Holter monitoring in 40 patients with a first uncomplicated MI. After baseline examination between 48 and 72 hours after symptom onset, patients were randomly assigned to placebo or captopril administration, and on the third day, 24-hour Holter monitoring was repeated. No changes in time and frequency domain were detectable after placebo. After captopril, the SD of all normal RR (NN) intervals (SDNN) increased from 90 +/- 29 to 105 +/- 30 milliseconds (P < .01); the SD of the average NN intervals for all 5-minute segments (SDANN index) and the mean of the SDs of all NN intervals for all 5-minute segments (SDNN index) also increased from 74 +/- 24 to 90 +/- 26 milliseconds (P < .01) and from 45 +/- 17 to 49 +/- 15 milliseconds (P < .05), respectively. The root mean square successive difference (r-MSSD) and the percent of differences between adjacent NN intervals > 50 milliseconds (pNN50) remained unchanged. In regard to frequency-domain measures, after captopril, total power (ln unit) increased from 8.28 +/- 0.42 to 8.47 +/- 0.30 (P < .01); considering the frequency bands, a significant increase was observed in ULF (P < .01), VLF (P < .05), and low-frequency (LF) power (P < .05), whereas high-frequency (HF) power remained unchanged. CONCLUSIONS: This study supports the hypothesis that the renin-angiotensin system modulates the amplitude of ULF and VLF power. Furthermore, it demonstrates that in MI patients, converting enzyme inhibition favorably modifies measures of heart period variability strongly associated with a poor prognosis.

Relationship between ventricular ectopic beat frequency and heart rate: study in patients with severe arrhythmias.

To evaluate and quantify the relationship between premature ventricular contractions (PVCs) and heart rate (HR), 57 patients (48 men and 8 women, mean age 59.8 +/- 7.9 years) with severe PVCs (Lown-Wolf grade > or = 3a) over 24 hours of Holter monitoring were studied. Twenty had no coronary artery disease (CAD), 25 had angiographically documented CAD, and 12 had acute myocardial infarction. All parameters of the 24-hour recordings from two ECG leads were measured by a Holter analyzer designed in our laboratory, based on fast microprocessors and controlled by a microcomputer. Scatter diagrams of the number of PVCs per minute as a function of HR and correlation coefficient were computed for various HR values corresponding to a total number of minutes greater than five. A positive correlation (r > or = 0.35) was found in most patients without CAD (85%); there was a complex relationship between the strength of the correlation and the presence of CAD or acute myocardial infarction because of a greater variability in the results of correlation coefficient analysis (coefficient of variation 62%, 208%, and 145% in patients without CAD, with CAD, and with acute myocardial infarction, respectively). The incidence of a positive correlation was similar in patients with Lown-Wolf grade III (63%), IVa (82%), or > or = IVb (67%) arrhythmias. The reproducibility of the correlation coefficient of the relationship between PVC frequency and HR was tested in 15 patients. The mean value of the correlation coefficient was 0.801 +/- 0.169 for the first test and 0.805 +/- 0.22 (p = NS) for the second test.(ABSTRACT TRUNCATED AT 250 WORDS)