Mood change and empathy decline persist during three years of internal medicine training.

PURPOSE: To examine longitudinal changes in mood and empathy over the course of the internal medicine residency. METHOD: The authors conducted a cohort study of 61 residents who completed the Profile of Mood States (POMS) and the Interpersonal Reactivity Index (IRI) at six time points during their internal medicine residency at a university-based program. (POMS was administered five times, and IRI was administered six times.) The main outcomes measured were trends in mood disturbances and multiple domains of empathy over the three-year residency, and comparisons to norms. RESULTS: Response rates varied from Time 1 to Time 6 (98%, 72%, 79%, 79%, 94%, and 95%, respectively). Interns had better scores on four POMS subscales: Depression-Dejection (p = .0031), Anger-Hostility (p < .0001), Fatigue-Inertia (p < .0001), and Vigor-Activity (p < .0001) compared with later administrations, especially midinternship. By the end of residency all POMS scores were returning towards baseline (effects sizes in the .20 s), but only depression was no longer significantly different. IRI scores showed the decline in Empathic Concern remained over residency whereas Personal Distress peaked midinternship year but approached baseline at the end of residency. Compared with the general population, the graduating residents were less tense, depressed, and confused. Personal Distress was significantly lower than the norm group. CONCLUSIONS: Internal medicine residency presents challenges resulting in common mood disturbances. Although graduating residents appear to be better off than the population norms, some domains of their mood disturbances and empathy never fully recover from their internship year.     

Autonomic cardiovascular response to acute hypoxia and passive head-up tilting in humans

Acute hypoxia may alter autonomic cardiovascular reflexes during orthostasis. Heart rate variability (HRV), arterial blood pressure (MAP), and respiratory sinus arrhythmia (RSA) were recorded during supine (SUP) and passive head up tilt (HUT) in eight healthy humans, spontaneously breathing either room air or 10 % O₂ in N₂. In the time domain, heart rate increased and variability decreased with HUT in both trials, with no difference between trials. In the frequency domain, normalized low frequency HRV increased, and normalized high frequency HRV decreased with HUT in both trials, with no difference between trials. MAP was 74.9 (8.6) and 77.5 (11.7) mmHg when SUP in the room air and hypoxia trials, respectively. A significant increase in MAP occurred with HUT in the room air trial but not in the hypoxia trial. In both trials, end tidal CO₂ decreased with HUT, with no difference between trials. In the room air trial, end tidal O₂ increased with HUT, whereas during the hypoxia trial, end tidal O₂ decreased with HUT. The distribution of heart beats relative to the phase of ventilation (%HB_IN and %HB_OUT) was similar in both trials: the %HB_IN was 43.5 (3.3) % and %HB_OUT was 56.5 (4.2) % breathing room air when SUP, and 45.5 (3.0) and 54.5 (3.2) when hypoxic and SUP. For both trials, this distribution did not change with HUT. As both HRV and RSA showed similar responses to HUT when spontaneously breathing either room air or 10 % O₂ in N₂, we suggest that autonomic cardiovascular reflexes are preserved during acute hypoxia.     

The utility of low frequency heart rate variability as an index of sympathetic cardiac tone: A review with emphasis on a reanalysis of previous studies

This article evaluates the suitability of low frequency (LF) heart rate variability (HRV) as an index of sympathetic cardiac control and the LF/high frequency (HF) ratio as an index of autonomic balance. It includes a comprehensive literature review and a reanalysis of some previous studies on autonomic cardiovascular regulation. The following sources of evidence are addressed: effects of manipulations affecting sympathetic and vagal activity on HRV, predictions of group differences in cardiac autonomic regulation from HRV, relationships between HRV and other cardiac parameters, and the theoretical and mathematical bases of the concept of autonomic balance. Available data challenge the interpretation of the LF and LF/HF ratio as indices of sympathetic cardiac control and autonomic balance, respectively, and suggest that the HRV power spectrum, including its LF component, is mainly determined by the parasympathetic system.     

Quantification of cumulated physical fatigue at the workplace

Quantification of physical fatigue remains a challenge. We hypothesized that its effects on central autonomic nervous system activity could be explored for such a quantification. To test this relationship, we prospectively measured central autonomic nervous activity through nocturnal heart rate variability (HRV) in six French garbage collectors, aged 32.1+/-4.3 years, twice a week during 3 consecutive weeks of work, and during the following week of rest. Eight healthy sedentary males formed a control group. HRV indices were calculated by applying standard temporal domain and wavelet transform analyses to standard ECG recordings. During the 3 consecutive weeks of work, there was a significantly progressive decrease in HRV indices, particularly pNN50 (-34.2%, P<0.05), as well as the high (-33.3%, P<0.05) and low (-22.2%, P<0.01) frequency components of wavelet transform, while there was an increase, although non-significant, of the ratio of low to high frequencies (9.1%). During the resting period, there was a significant recovery of HRV indices, notably of its high (50.0%, P<0.05) and low (28.6%, P<0.05) frequency components. No such changes occurred in the control group. A central signature of cumulated physical fatigue can thus be detected and quantified through nocturnal autonomic nervous system activity. Its characteristics are those of a progressive parasympathetic withdrawal.     

Relationship among nausea,anxiety, and orthostatic symptoms in pediatric patients with chronic unexplained nausea

This study evaluated the relationship among nausea, anxiety, and orthostatic symptoms in pediatric patients with chronic unexplained nausea. We enrolled 48 patients (36 females) aged 15 ± 2 years. Patients completed the Nausea Profile, State-Trait Anxiety Inventory for Children and underwent 70° head upright tilt testing (HUT) to assess for orthostatic intolerance (OI) and measure heart rate variability (HRV). We found nausea to be significantly associated with trait anxiety, including total nausea score (r = 0.71, p < 0.01) and 3 subscales: somatic (r = 0.64, p < 0.01), gastrointestinal (r = 0.48, p = 0.01), and emotional (r = 0.74, p < 0.01). Nausea was positively associated with state anxiety, total nausea (r = 0.55, p < 0.01), somatic (r = 0.48, p < .01), gastrointestinal (r = .30, p < .05), and emotional (r = .64, p < .01) subscales. Within 10 min of HUT, 27 patients tested normal and 21 demonstrated OI. After 45 min of HUT, only 13 patients (27 %) remained normal. Nausea reported on the Nausea Profile before HUT was associated with OI measured at 10 min of tilt (nausea total r = 0.35, p < 0.05; nausea emotional subscale r = 0.40, p < 0.01) and lower HRV at 10 min of HUT (F = 6.39, p = 0.01). We conclude that nausea is associated with both anxiety symptoms and OI. The finding of decreased HRV suggests an underlying problem in autonomic nervous system function in children and adolescents with chronic unexplained nausea.     

Sedative effects of the jasmine tea odor and (R)-(−)-linalool, one of its major odor components, on autonomic nerve activity and mood states

We investigated the effects of the odor of jasmine tea on autonomic nerve activity and mood states in a total of 24 healthy volunteers. We used the odor of jasmine tea at the lowest concentration that could be detected by each subject but that did not elicit any psychological effects. R–R intervals and the POMS test were measured before and after inhalation of the odors for 5 min. Both jasmine tea and lavender odors at perceived similar intensity caused significant decreases in heart rate and significant increases in spectral integrated values at high-frequency component in comparison with the control (P < 0.05). In the POMS tests, these odors produced calm and vigorous mood states. We also examined the effects of (R)-(–)-linalool, one of its major odor components, at the same concentration as in the tea, and (S)-(+)-linalool. Only (R)-(–)-linalool elicited a significant decrease in heart rate (P < 0.05) and an increase in high-frequency component in comparison with the controls, and produced calm and vigorous mood states. Thus, the low intensity of jasmine tea odor has sedative effects on both autonomic nerve activity and mood states, and (R)-(–)-linalool, one of its components, can mimic these effects.     

Multi-and monofractal indices of short-term heart rate variability

Indices of heart rate variability (HRV) based on fractal signal models have recently been shown to possess value as predictors of mortality in specific patient populations. To develop more powerful clinical indices of HRV based on a fractal signal model, the study investigated two HRV indices based on a monofractal signal model called fractional Brownian motion and an index based on a multifractal signal model called multifractional Brownian motion. The performance of the indices was compared with an HRV index in common clinical use. To compare the indices, 18 normal subjects were subjected to postural changes, and the indices were compared on their ability to respond to the resulting autonomic events in HRV recordings. The magnitude of the response to postural change (normalised by the measurement variability) was assessed by analysis of variance and multiple comparison testing. Four HRV indices were investigated for this study: the standard deviation of all normal R-R intervals; an HRV index commonly used in the clinic; detrended fluctuation analysis, an HRV index found to be the most powerful predictor of mortality in a study of patients with depressed left ventricular function; an HRV index developed using the maximum likelihood estimation (MLE) technique for a monofractal signal model; and an HRV index developed for the analysis of multifractional Brownian motion signals. The HRV index based on the MLE technique was found to respond most strongly to the induced postural changes (95% Cl). The magnitude of its response (normalised by the measurement variability) was at least 25% greater than any of the other indices tested.     

Effect of dried-bonito broth on mental fatigue and mental task performance in subjects with a high fatigue score

Dried-bonito broth is commonly employed as a soup and sauce base in Japanese cuisine and is considered to be a nutritional supplement that promotes recovery from fatigue. Previous human trials suggest that the ingestion of dried-bonito broth improves several mood states; however, its effect on fatigue has not yet been clarified. The aim of this study was to clarify the effects of daily ingestion of dried-bonito broth on fatigue and cognitive parameters by a placebo-controlled double blind crossover trial. Forty-eight subjects with fatigue symptoms ingested the dried-bonito broth or a placebo solution every day for 4 weeks. Mood states were evaluated by the Profile of Mood States (POMS), and mental task performance was evaluated by the Uchida-Kraepelin psychodiagnostic (UKP) test. Fatigue and total mood disturbance (TMD) scores on the POMS test decreased significantly during the dried-bonito broth ingestion (p<0.05), but did not change significantly during placebo ingestion. The change in vigor score during dried-bonito broth ingestion was significantly higher than that during placebo ingestion at 2 weeks (p<0.05). The results of the UKP test indicate that the numbers of both total answers and correct answers significantly increased during dried-bonito broth ingestion (p<0.05), while no significant changes were observed in the placebo ingestion. These results suggest that the daily ingestion of dried-bonito broth may improve the mood states, may reduce mental fatigue and may increase performance on a simple calculation task.     

Evaluation of mental stress tests among medical students based on salivary sample collected just before the national license examination

We investigated salivary amylase (sAMY) and chromogranin A (sCgA) in students before the national license examination in order to investigate the relationship between stress biomarkers and the Profile of Mood States (POMS) psychological test. Fifty-one medical students that provided informed consent were tested for sAMY activity and sCgA concentration by means of the amylase monitor method (NIPRO) and an ELISA kit (Yanaihara), respectively. The POMS psychology test (shortened form) was purchased from Chiba Test Center, and all students fully answered the lifestyle questionnaires. Based on answers to the questionnaires, students were divided by mental burden into three groups: I all"; II "large"; and III "very large". Scores for "T-A", "D" and "A-H" on the POMS test were significantly higher in groups II and III when compared with group I. Mean TMD scores calculated from the 6 items on the POMS test increased significantly with mental burden. The mean levels and 95% confidence interval (CI) of sAMY activity in the 3 groups were as follows: I, 27.7 (95% CI: 13.7-41.7) KIU/L; II, 29.1(95% CI: 22.4-35.7) KIU/L; and III, 26.9 (95% CI: 15.2-38.6) KIU/L. Mean sCgA concentrations were: I, 4.4(95% CI: 0-9.4) pmol/mg; II, 4.3(95% CI: 2.0-6.7) pmol/mg; and III, 10.9 (95% CI: 6.8-15.0) pmol/mg. There were no significant differences between these mean levels. However, Spearman's rank-correlation coefficient analysis for "T-A", sAMY and sCgA showed a stronger correlation between "T-A" and sCgA than between "T-A" and sAMY (p < 0.05). In conclusion, sCgA was more useful biomarker to evaluate the psychological stress before the national license examination than sAMY.     

慢性肾衰患者心率变异性改变

目的　通过心率变异性 (HRV)变化测定 ,探讨慢性肾功能衰竭 (CRF)患者的自主神经活动状况。方法　用2 4小时动态心电图分析系统 ,对 2 0例健康者 ,77例CRF患者 (其中 30例氮质血症 ,4 7例尿毒症 )心率变异性的时域指标进行对比研究。结果　CRF患者心率变异性的测定结果为 :SDNN 85 .2 8± 19.96 ,SDANN 75 .5 5± 2 2 .4 7,r-MSSD19.2 2± 11.82 ,PNN50 6 .7± 14 .79,各项指标均明显低于健康者 (P <0 .0 1)。氮质血症期与尿毒症期心率变异性无明显差别。结论　通过HRV时域分析发现 ,CRF患者有自主神经调节功能紊乱。CRF氮质血症期患者已出现HRV下降 ,提示CRF患者早期就存在自主神经功能损害。     

健康男性中A型行为模式对心脏自主神经活动的影响

目的:在诱发负性情绪条件下,研究健康男性中A型行为模式对心脏自主神经活动的影响。方法:采用两因素重复测量设计,分别考察A型和B型、高TH组和低TH组、高CH组与低CH组,在三种情绪应激状态下心率变异性各频域指标的差异。结果:无论按AB型整体分类,还是按CH和TH特质分类,在心率变异性(HRV)各频域指标上组间均无显著差异,被试类型与负性情绪应激水平均无显著交互作用。而三种情绪应激状态主效应显著,均表现为:在预期阶段和应对阶段两种应激状态下,交感神经功能的相对兴奋及迷走神经功能的相对抑制,交感-迷走神经的不平衡性增加。结论:健康男性中A型行为及其部分特质对心脏自主神经活动的影响均不显著,情绪应激对心脏自主神经活动的影响是直接而显著的,并且表现为冠心病病理状态下相似的变化特征。     

倾斜实验中脑心耦合关系研究

大脑皮层能够通过自主神经系统对心血管活动进行调控,其机理的研究对心律不齐、高血压、心衰等疾病的诊疗与防控有重要的价值。同步采集27名健康被试在静息和70 °直立倾斜实验(HUT)中前额叶皮层(MPFC)的近红外光谱和心电、连续血压及胸阻抗信号,通过心率变异性、格兰杰因果方法(GC)等研究心血管参数的变化,以及MPFC血流量与交感/副交感输出流(由nLF和HF表示)、RRI的耦合关系。研究结果显示:HUT实验中心输出量(CO)平均减少24%(P<0.001),心率(HR)增加35%(P<0.001),舒张压(DBP)升高7%(P<0.001),收缩压(SBP)在HUT初期降低,但均值较静息状态无明显变化;nLF逐渐增强,HF逐渐减弱,随后分别保持高于38.75±9.25 vs 58.62±8.58(P<0.001)和低于1.11±0.76 vs 0.80±0.48(P<0.05)静息状态的稳定水平;MPFC血流量与交感和副交感输出流显著相关,相关系数分别为0.58和0.66;GC分析显示频段特异性,在0.04~0.15 Hz(主频0.1 Hz)频段表现为“脑→心”(P<0.05),而在0.15~0.4 Hz(主频0.3 Hz)频段表现为“心→脑”(P<0.001)。研究结果表明:HUT能引起显著的心血管响应,主要由交感和副交感输出流所调控;MPFC参与该响应过程,且由主频0.1 Hz的低频振荡信号(～0.1 Hz)介导其与自主输出流的联系。研究发现脑心耦合的新证据,即健康机体在直立应激过程中的脑心交互特征,～0.1 Hz振荡信号在介导MPFC调控自主输出流方面具有重要作用。     

Patterns of mood states in pregnant women undergoing chorionic villus sampling or amniocentesis

The purpose of this study was to compare patterns of self-reported mood states of women having chorionic villus sampling (CVS) (n = 151) to those of women electing amniocentesis (n = 30) with the indication of advanced maternal age. Mood states were defined as scores on the 6 subscales of the Profile of Mood States (POMS). Women at 4 U.S. prenatal diagnostic facilities completed the POMS at 4 assessment periods. These were a) at their initial genetic counseling session, b) 2 weeks post CVS results (or an equivalent time), c) 2 weeks post amniocentesis results (or an equivalent time), and d) at 30 weeks gestation. Repeated measures analysis of variance revealed that anxiety, fatigue, and confusion decreased, and vigor increased in both groups as the pregnancy progressed. Depression decreased in both groups and then increased at assessment 4 in women in the amniocentesis group but not in those electing CVS. Results should be interpreted in conjunction with obstetrically and genetically-oriented findings regarding safety and accuracy to help women decide between the 2 procedures.     

Effect of estrogen replacement therapy on symptoms of depression and anxiety in non-depressive menopausal women: a randomized double-blind, controlled study

The efficacy of estrogen replacement therapy (ERT) for mood disturbances associated with menopause has yet to be firmly established. The objective of this study was to investigate the efficacy of ERT for improving mood and anxiety of non-depressive postmenopausal women. This double-blind, randomized, placebo-controlled study involved two treatment groups: one receiving conjugated equine estrogens (CEEs; 0.625 mg/day) and the other placebo, for six cycles of 28 days each. Subjects were hysterectomized, healthy, non-depressive (according to Schedule for Affective Disorders and Schizophrenia, Life Time Version [SADS-L]) women. Depressive and anxiety symptoms were assessed with the Beck Depression Inventory (BDI), and the Hamilton Anxiety Scale (HAMA), respectively. The Profile of Mood States (POMS) and other scales were used to characterize symptoms. In both groups, BDI scores were significantly lower at cycles 1, 2, 3, and 6, compared with baseline assessments (p < 0.01). Anxiety scores for both groups significantly improved from cycle 3 to study endpoint. The only significant difference favoring the active group occurred at cycle 1. POMS scores were significantly improved at the end of cycles 1, 2, 3 and 6 among treated subjects and at the end of cycles 2, 3, and 6 among placebo subjects. ERT is not associated with improvements in mood or anxiety symptoms in non-depressive, hysterectomized, postmenopausal women.     

Correlation between the severity of obstructive sleep apnea and heart rate variability indices

The risk of cardiovascular disease is known to be increased in obstructive sleep apnea syndrome (OSAS). Its mechanism can be explained by the observation that the sympathetic tone increases due to repetitive apneas accompanied by hypoxias and arousals during sleep. Heart rate variability (HRV) representing cardiac autonomic function is mediated by respiratory sinus arrhythmia, baroreflex-related fluctuation, and thermoregulation-related fluctuation. We evaluated the heart rate variability of OSAS patients during night to assess their relationship with the severity of the symptoms. We studied overnight polysomnographies of 59 male untreated OSAS patients with moderate to severe symptoms (mean age 45.4+/- 11.7 yr, apnea-hypopnea index [AHI]=43.2+/-23.4 events per hour, and AHI >15). Moderate (mean age 47.1+/-9.4 yr, AHI=15-30, n=22) and severe (mean age 44.5 +/-12.9 yr, AHI >30, n=37) OSAS patients were compared for the indices derived from time and frequency domain analysis of HRV, AHI, oxygen desaturation event index (ODI), arousal index (ArI), and sleep parameters. As a result, the severe OSAS group showed higher mean powers of total frequency (TF) (p=0.012), very low frequency (VLF) (p= 0.038), and low frequency (LF) (p=0.002) than the moderate OSAS group. The LF/HF ratio (p=0.005) was higher in the severe group compared to that of the moderate group. On the time domain analysis, the HRV triangular index (p=0.026) of severe OSAS group was significantly higher. AHI was correlated best with the LF/HF ratio (r(p))=0.610, p<0.001) of all the HRV indices. According to the results, the frequency domain indices tended to reveal the difference between the groups better than time domain indices. Especially the LF/HF ratio was thought to be the most useful parameter to estimate the degree of AHI in OSAS patients.     

Correlation between heart rate variability and pulmonary function adjusted by confounding factors in healthy adults

The autonomic nervous system maintains homeostasis, which is the state of balance in the body. That balance can be determined simply and noninvasively by evaluating heart rate variability (HRV). However, independently of autonomic control of the heart, HRV can be influenced by other factors, such as respiratory parameters. Little is known about the relationship between HRV and spirometric indices. In this study, our objective was to determine whether HRV correlates with spirometric indices in adults without cardiopulmonary disease, considering the main confounders (e.g., smoking and physical inactivity). In a sample of 119 asymptomatic adults (age 20-80 years), we evaluated forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV₁). We evaluated resting HRV indices within a 5-min window in the middle of a 10-min recording period, thereafter analyzing time and frequency domains. To evaluate daily physical activity, we instructed participants to use a triaxial accelerometer for 7 days. Physical inactivity was defined as <150 min/week of moderate to intense physical activity. We found that FVC and FEV₁, respectively, correlated significantly with the following aspects of the RR interval: standard deviation of the RR intervals (r =0.31 and 0.35), low-frequency component (r =0.38 and 0.40), and Poincaré plot SD2 (r =0.34 and 0.36). Multivariate regression analysis, adjusted for age, sex, smoking, physical inactivity, and cardiovascular risk, identified the SD2 and dyslipidemia as independent predictors of FVC and FEV₁ (R ²=0.125 and 0.180, respectively, for both). We conclude that pulmonary function is influenced by autonomic control of cardiovascular function, independently of the main confounders.     

Differential mood changes in alcoholics as a function of anxiety management strategies.

A study was designed to compare the effects of three relaxation strategies on mood state profiles in a group of 30 male alcoholics. The Profile of Mood States (POMS) was used for pre- and posttest treatment measures. The results indicated that the three relaxation strategies--progressive relaxation training, (PRT), meditation training (MT), quiet rest (QR)--produced qualitatively different patterns. While both PRT and MT produced measurable decrements in self-reported tension and QR controls showed no change on any of the six subscales, PRT was observed to effect decreased depression as well as a trend toward increased vigor. Meditation training effects were limited to decreased tension and a nonsignificant decrease in fatigue. These results are discussed in terms of refinement of the "relaxation response" notion to a more heterogeneous, technique-centered definition.     

Concurrent validity of the clinical symptom syndrome scales of the millon clinical multiaxial inventory

This study examined relationships between the clinical symptom syndrome scales of the Millon Clinical Multiaxial Inventory (MCMI) and the various clinically meaningful mood or symptom states measured by the six Profile of Mood States (POMS) scales (N = 243). The MCMI symptom scale—POMS symptom/mood scale relationships found in this study were compared with MCMI symptom scale—MMPI and SCL-90 symptom/mood scale relationships reported in the MCMI manual (Millon, 1983). Results of the present investigation, when combined with results of the previous analyses reported in the MCMI manual, reveal a number of consistent associations of moderate strength between MCMI symptom scales and selected mood or symptom scales from the MMPI and Symptom Checklist-90 as well as from the POMS. Although most relationships between the MCMI symptom scales and the symptom/mood scales of the POMS, MMPI and SCL-90 were consistent with expectation, the Anxiety, Dsythymia and Psychotic Depression scales of the MCMI show limited ability to discriminate appropriately between anxiety and depression in several of the concurrent validity analyses considered herein.     

Effects of exercise training on autonomic modulation and mood symptoms in patients with obstructive sleep apnea

We evaluated the effects of exercise training (ET) on the profile of mood states (POMS), heart rate variability, spontaneous baroreflex sensitivity (BRS), and sleep disturbance severity in patients with obstructive sleep apnea (OSA). Forty-four patients were randomized into 2 groups, 18 patients completed the untrained period and 16 patients completed the exercise training (ET). Beat-to-beat heart rate and blood pressure were simultaneously collected for 5 min at rest. Heart rate variability (RR interval) was assessed in time domain and frequency domain (FFT spectral analysis). BRS was analyzed with the sequence method, and POMS was analyzed across the 6 categories (tension, depression, hostility, vigor, fatigue, and confusion). ET consisted of 3 weekly sessions of aerobic exercise, local strengthening, and stretching exercises (72 sessions, achieved in 40±3.9 weeks). Baseline parameters were similar between groups. The comparisons between groups showed that the changes in apnea-hypopnea index, arousal index, and O₂ desaturation in the exercise group were significantly greater than in the untrained group (P<0.05). The heart rate variability and BRS were significantly higher in the exercise group compared with the untrained group (P<0.05). ET increased peak oxygen uptake (P<0.05) and reduced POMS fatigue (P<0.05). A positive correlation (r=0.60, P<0.02) occurred between changes in the fatigue item and OSA severity. ET improved heart rate variability, BRS, fatigue, and sleep parameters in patients with OSA. These effects were associated with improved sleep parameters, fatigue, and cardiac autonomic modulation, with ET being a possible protective factor against the deleterious effects of hypoxia on these components in patients with OSA.     

Heart rate variability and its determinants in patients with severe or mild essential hypertension.

How cardiac autonomic nervous control is related to the severity of essential hypertension in patients receiving long-term antihypertensive therapy is not well known. The aim of this study was to examine heart rate variability (HRV), a non-invasive measure of cardiac autonomic function, in patients with long-term and medically treated mild and severe essential hypertension and healthy control subjects, and to assess the clinical determinants of HRV in these patients. Thirty-four patients with severe essential hypertension (SEHT) and 29 with mild essential hypertension (MEHT) as well as healthy age- and sex-matched control subjects were studied. HRV was assessed from 10 min ECG-recordings during paced (0.2 Hz) breathing at rest and expressed as time and frequency domain measures. In the SEHT group time (SDNN, RMSSD) and frequency domain measures (total power, low-frequency (LF) power and high-frequency (HF) power of HRV in absolute units, and LF and HF power of HRV in normalized units) of HRV were significantly lower when compared with those of the control group. The MEHT and control groups did not differ from each other with respect to time or frequency domain measures of HRV. Comparison between the hypertensive groups showed that SDNN, total power, LF power and HF power were lower in the SEHT group compared with the MEHT group (P<0.05 for all). Among hypertensive patients RR-interval, age, gender, systolic finger blood pressure and diastolic office blood pressure as well as 24-h blood pressure were significant determinants of HRV. In conclusion, we found that the severity of chronic essential hypertension seems to be related to the severity of impairment of cardiac autonomic control.