Non-invasive blood pressure variability in chronic heart failure: characteristics and prognostic value

BACKGROUND: Short-term variability of blood pressure can be used as an index of sympathetic vascular modulation and has been studied in patients with hypertension. AIM: The aim of this study was to characterise blood pressure variability (BPV) and its prognostic value in patients with congestive heart failure. METHODS AND RESULTS: 104 patients with congestive heart failure due to ischemia (n = 104) or idiopathic cardiomyopathy (n = 50) in New York Heart Association (NYHA) class II (n = 50), III (n = 71), IV (n = 33), and 40 healthy subjects were studied. The mean ejection fraction was 0.33 +/- 0.10. Continuous non-invasive BP recordings were obtained for 3,600 seconds with a photoplethysmographic finger device in patients and control subjects at rest. Patients with chronic heart failure (CHF) had significantly less pronounced BPV than control subjects. Diastolic blood pressure (DBP) variability was related to left ventricular ejection and to peak oxygen uptake. BPV was not different in patients with ischemic or idiopathic CHF. During the mean follow up (+/- SD) of 565 +/- 215 days, 44 patients died (28.6%). All deaths were cardiac related. Cox's univariate analysis identified the following factors to be predictors of death: peak oxygen uptake (p = 0.01), ejection fraction (p = 0.008), and among BPV parameters: total spectral amplitude (TA) for DBP (p = 0.002), very low frequencies over total amplitude (VLF/TA) for DBP (p = 0.005) and for mean blood pressure (MBP) (p = 0.03), and very low over high frequencies ratio (VLF/HF) for DBP (p = 0.002). Multivariate analysis showed that BPV predicted survival independently of EF or peak VO2. Kaplan-Meier survival curves revealed that VLF/TA < 55% for DBP, MBP and SBP are useful risk factors. One-year survival in patients with VLF/TA < 55% of DBP was 53% compared with 95% in those with VLF/TA > 55% (p = 0.005). CONCLUSIONS: Decreased BPV in patients with CHF is related to left ventricular dysfunction. Analysis of BPV can identify patients with CHF who have an increased risk of cardiac death.     

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.     

Control of blood pressure variability in caveolin-1-deficient mice: role of nitric oxide identified in vivo through spectral analysis

AIMS: In endothelial cells, caveolin-1 (cav-1) is known to negatively modulate the activation of endothelial nitric oxide synthase, a key regulator of blood pressure (BP). However, the impact of genetic alteration of cav-1 on vascular nitric oxide (NO) production and BP homeostasis in vivo is unknown. METHODS AND RESULTS: We used spectral analysis of systolic blood pressure (SBP) variability in mice chronically equipped with telemetry implants to identify frequency ranges (0.05-0.4 Hz; very low frequency, VLF) specifically responding to NO, independently of changes in absolute BP or systemic neurohormone levels. VLF variability was inversely correlated to aortic vasodilator-stimulated Ser(239) phosphoprotein (VASP) phosphorylation, reflecting NO bioactivity. We show that mice deficient in cav-1 have decreased VLF variability paralleled with enhanced systemic and vascular production of NO at unchanged mean SBP levels. Conversely, VLF variability was increased upon acute injection of mice, with a peptide containing the caveolin-scaffolding domain (CSD; residues 82-101) fused to an internalization sequence of antennapedia that decreased vascular and circulating NO in vivo. CONCLUSION: These data highlight the functional importance of cav-1 for the production of bioactive NO in conduit arteries and its control of central BP variability. Given the impact of the latter on target organ damage, this raises the interest for genetic, pharmacological, or molecular interventions that modulate cav-1 expression in diseases with NO-dependent endothelial dysfunction.     

老年糖尿病手术患者自主神经功能与无症状性心肌缺血的关系

目的探讨老年糖尿病(DM)患者手术前后心脏自主神经功能变化与无症状性心肌缺血(SMI)的关系。方法选择择期非心脏手术老年患者54例,其中非DM患者18例(NDM组),DM患者16例(DM组),DM合并SMI患者20例(SMI组)。监测3组患者心率变异性的变化,包括总功率(TP)、高频功率(HF)、低频功率(LF)、极低频功率(VLF)及LF/HF。结果与NDM组比较,DM组及SMI组术前TP、HF显著降低(P<0.05)。3组术后TP、HF、LF及VLF总的趋势是降低,其中SMI组下降最为明显。术后1天,SMI组TP、HF及VLF与术前比较明显降低,TP、HF、LF及VLF与NDM组差异明显(P<0.01,P<0.05),HF和VLF与DM组差异明显(P<0.05)。术后2天,除DM组LF外,3组TP、HF、LF及VLF分别与术前形成明显差异(P<0.05,P<0.01)。结论DM患者合并有心脏自主神经病变,手术应激引起机体自主神经调节心脏功能的进一步紊乱,是造成DM患者围手术期SMI高发的重要原因。     

Noninvasive measure of microvascular nitric oxide function in humans using very low-frequency cutaneous laser Doppler flow spectra

OBJECTIVE: While higher frequency oscillations (0.021-0.6 Hz) in cutaneous blood flow measured by laser Doppler flowmetry (LDF) relate to oscillations in blood pressure and sympathetic nerve activity, very low-frequency oscillations (VLF, 0.0095-0.021 Hz) do not. The authors investigated whether VLF LDF power is nitric oxide (NO) specific. METHODS: LDF combined with intradermal microdialysis was used in the calves of 22 healthy volunteers aged 19-27 years. LDF power spectral analysis was performed by windowed fast Fourier transform. The authors tested whether the NO synthesis inhibitor nitro-l-arginine (NLA) produced selective decreases in VLF power before and after stimulation with acetylcholine. RESULTS: NLA alone did not alter total power but selectively reduced VLF power by approximately 50%. LDF and spectral power increased markedly across all spectra with acetylcholine. This increase was blunted by NLA, which selectively reduced VLF power by approximately 50%. CONCLUSIONS: The data suggest that VLF oscillations in the laser Doppler signal are NO dependent, increase with cholinergic stimulation, and have potential as a noninvasive marker for NO-dependent microvascular reactivity.     

Fetal wastage in women with anti-Ro(SSA) antibody

Retrospective obstetric histories were obtained in 50 anti-Ro(SSA) antibody positive women (aged 15-50 years) and 47 anti-nRNP antibody positive women of similar age range. Twenty (40%) anti-Ro(SSA) positive women and 33 (70%) anti-nRNP positive women fulfilled the revised ARA criteria for systemic lupus erythematosus (SLE). Thirty-four anti-Ro(SSA) positive women had a total of 84 pregnancies with a fetal loss of 28%; 29 anti-nRNP positive women had a total of 63 pregnancies with a fetal loss of 19%. Although the overall frequency of fetal wastage between the 2 groups was not significantly different, analysis of the subgroup of SLE patients demonstrated a significantly greater fetal wastage in black anti-Ro(SSA) positive women (15 of 21, 71%) compared with black anti-nRNP positive women (5 of 28, 18% p less than .001). No significant difference in fetal wastage was noted between either the white SLE or the non-SLE women in either antibody group. These data suggest that black SLE patients with anti-Ro(SSA) antibody may be at increased risk of fetal wastage.     

Heart rate variability. Frequency domain analysis.

Experience with frequency domain analysis over the past two decades strongly suggests that it represents a unique, noninvasive tool for achieving a more precise assessment of autonomic function in both the experimental and clinical settings. Available studies indicate that the significance of the HF component is far better understood than that of the lower frequency components. In general, it is considered to reflect vagal activity, and because it is readily manipulated pharmacologically, is used as a an index of that activity. However, some caution is required because this parameter also is strongly influenced by the degree of coupling between respiration and heart rate, which, in turn, reflects the intensity of the respiratory effort as well as of parasympathetic activity. Respiratory pattern also can significantly influence HF power. The use of controlled breathing minimizes these problems, improves reproducibility of test findings, and also facilitates quantitative comparisons. The situation with respect to LF power is more complicated because it is modulated by both sympathetic and parasympathetic outflows (see previous discussion) as well as by other factors, including baroreceptor activity. Therefore, LF analysis per se cannot afford a precise delineation of the state of sympathetic activation. Determinations of the LF/HF ratio, an index of sympathovagal balance both under control conditions and in conjunction with interventions that maximize sympathetic and parasympathetic activity, provide additional insights, as do correlations between spectral activity and direct nerve recordings, plasma norepinephrine concentrations, and radionuclide imaging of adrenergic nerves. Renewed interest has recently been evinced in frequencies lower than 0.04 Hz in view of reports that the VLF portion of the spectrum (0.01-0.04 Hz) reflects a purer form of sympathetic activity than does the LF band. Despite the potential applicability to clinical problems, only very little is known about the physiologic basis of the VLF and ULF bands. Further study is required. However, it is important to note that meaningful determinations of VLF and ULF power may be difficult because decreases in frequency to such low levels are associated with an increasing propensity to violate the rules governing power spectral determinations (see previous discussion and appendix), violations that diminish reliability despite the most sophisticated preprocessing. It is also noteworthy that the reliability of spectral power determinations diminishes with decreases in the power of the signal and of the signal-to-noise ratio.(ABSTRACT TRUNCATED AT 400 WORDS)     

Frequency domain measures of heart period variability and mortality after myocardial infarction.

BACKGROUND. We studied 715 patients 2 weeks after myocardial infarction to establish the associations between six frequency domain measures of heart period variability (HPV) and mortality during 4 years of follow-up. METHODS AND RESULTS. Each measure of HPV had a significant and at least moderately strong univariate association with all-cause mortality, cardiac death, and arrhythmic death. Power in the lower-frequency bands--ultra low frequency (ULF) and very low frequency (VLF) power--had stronger associations with all three mortality end points than power in the higher-frequency bands--low frequency (LF) and high frequency (HF) power. The 24-hour total power also had a significant and strong association with all three mortality end points. VLF power was the only variable that was more strongly associated with arrhythmic death than with cardiac death or all-cause mortality. In multivariate Cox regression models using a step-up approach to evaluate the independent associations between frequency domain measures of heart period variability and death of all causes, ULF power was selected first (i.e., was the single component with the strongest association). Adding VLF or LF power to the Cox regression model significantly improved the prediction of outcome. With both ULF and VLF power in the Cox regression model, the addition of the other two components, LF and HF power, singly or together, did not significantly improve the prediction of all-cause mortality. We explored the relation between the heart period variability measures and all-cause mortality, cardiac death, and arrhythmic death before and after adjusting for five previously established postinfarction risk predictors: age, New York Heart Association functional class, rales in the coronary care unit, left ventricular ejection fraction, and ventricular arrhythmias detected in a 24-hour Holter ECG recording. CONCLUSIONS. After adjustment for the five risk predictors, the association between mortality and total, ULF, and VLF power remained significant and strong, whereas LF and HF power were only moderately strongly associated with mortality. The tendency for VLF power to be more strongly associated with arrhythmic death than with all-cause or cardiac death was still evident after adjusting for the five covariates. Adding measures of HPV to previously known predictors of risk after myocardial infarction identifies small subgroups with a 2.5-year mortality risk of approximately 50%.     

抗原处理相关转运体基因与系统性红斑狼疮及自身抗体的相关性

目的 探讨皖籍汉族人群抗原处理相关转运体(transporter associated with antigen processing,TAP)基因与系统性红斑狼疮(systemic lupus erythematosus,SLE)及自身抗体的相关性。方法 应用聚合酶链反应—序列特异性寡核苷酸探针杂交(PCR—SSO))技术对80例SLE患者及96名正常对照人群进行TAP1、TAP2等位基因分型，按实验室常规检测ANA、抗dsDNA、抗RNP、抗Sm、抗SSA、抗SSB抗体。结果 本研究人群的TAP1和TAP2各有4种等位基因型，其频率依次为TAP1*0101＞*020l＞*0301＞*0401，TAP2*0101＞*0201＞*0102＞*0202，有6．8％(12／176)的研究对象用TAPl探针无法定型，10．2％(18／176)TAP2无法定型，呈杂交空白。SLE患者与正常对照人群间TAP等位基因型分布差异无显著性(P＞0．05)。抗RNP抗体与TAP1*0401呈正相关，抗dsDNA及抗SSA抗体与TAP2*0201呈正相关(P＜0．05)。结论 末证明TAP等位基因与SLE的相关性。TAP等位基因与自身抗体的相关性可能和TAP与HLA基因存在连锁不平衡现象有关。     

Effects of Postectopic Heart Rate Turbulence on Measures of Heart Rate Variability in Patients after an Acute Myocardial Infarction

Background: Heart rate (HR) turbulence lasting up to 15 beats after ventricular premature beats (VPBs) may have profound effects on HR variability measures. Aim of this study was to examine the effects of HR turbulence on HR variability measures. Methods: We developed an algorithm, which deletes 15 consecutive RR intervals after VPBs and examined the effects of the HR turbulence removal on the HR variability measures in patients after an acute myocardial infarction (AMI). Two hundred and sixty seven patients with left ventricular ejection fraction (LVEF) ≤ 0.40 and occurrence of VPBs were included in the study. Differences (%) between original HR data and HR turbulence edited data were compared. Results: HR turbulence editing had variable effects on different HR variability indexes. Ultra low (ULF) and very low frequency (VLF) spectral components were mostly affected by the HR turbulence removal. Both ULF and VLF decreased significantly both at baseline Holter recordings (ULF: P = 0.006, VLF: P = 0.031) and at 6 weeks from AMI (ULF: P < 0.001, VLF: P = 0.001). The number of VPBs had a marked influence on results, e.g., when the number of VPBs exceeded the highest decile (≈50 VPBs/hour), the ULF and VLF spectral component were >30% lower after removal of turbulence. In addition, the prediction of arrhythmic events by ULF component improved after turbulence removal (AUC: 0.69 ‐>0.74). Conclusions: HR turbulence affects HR variability measures, especially the ULF and VFL spectral components. Editing of the HR turbulence should be considered when HR variability is measured from Holter recordings. Ann Noninvasive Electrocardiol 2011;16(2):123–130     

Smoking, leukocyte count, and ventilatory lung function in working men

Results of a cross-sectional study of ventilatory lung function (VLF) in a group of 307 working men showed that the leukocyte count in peripheral blood is more closely associated with the relative position (percentile) of a person in the frequency distribution of VLF than is smoking intensity. Leukocyte count is significantly (and inversely) correlated with VLF in nonsmokers as well as in smokers. A multiple regression analysis indicated that, after accounting for the effect of height and age, white blood cell (WBC) count explains more of the VLF variance than many other health determinants. Moreover, WBC count is the only variable, apart from height and age, that contributes significantly to the regression. Current smokers with elevated leukocyte count in peripheral blood may constitute a defined high-risk group because they demonstrate more negative regression age coefficients when compared with smokers without elevated WBC or with nonsmokers. Mechanisms that may explain these findings are discussed.     

Apnea‐Related Heart Rate Variability and Its Clinical Utility in Congestive Heart Failure Outpatients

Background: Cheyne‐Stokes breathing (CSB) is an abnormal cyclical pattern of respiratory fluctuations observed during sleep in congestive heart failure (CHF) of poor prognosis. We examined the clinical usefulness of CSB screening using the heart rate variability (HRV) data from the ambulatory electrocardiogram. Methods: We monitored ambulatory electrocardiograms and respiration simultaneously in 86 heart disease patients of both sexes, aged 57 ± 1 years. HRV was analyzed by the maximum entropy method during the sleeping period (11 PM—S AM). The 43 CHF patients underwent a 1‐year follow‐up study. Results: In the power spectra of the HRV, peaks were observed within the CSB band (0.005 to 0.03 Hz). Statistically significant differences in HRV were observed between CSB patients and CSB‐free patients in very low frequency (VLF) (P = 0.04), VLF/total frequency (TF) (P = 0.02), CSB (P = 0.01), CSB/TF (P = 0.003), and CSB/VLF (P < 0.0001). Cardiac events occurred in 23% of patients, including cardiac death in two, and rehospitalization for aggravated CHF in eight. In a multivariate Cox regression analysis in which age, sex, ejection fraction, NYHA functional class, beta blocker use, and basic heart disease were included, absence of ACE inhibitor use (RR 5.5, 95% Cl 1.0–31) and CSB/VLF ≧ 80% (RR 4.2, 95% Cl 1.1–17) remained significant predictors of cardiac events. Conclusions: HRV can act as an indicator of the presence of CSB in CHF patients, and could therefore be used, under outpatient conditions, to identify a CHF patients with a poor prognosis. A.N.E. 2002;7(2):127–132     

Reproducibility and Gender‐Related Differences of Heart Rate Variability during All‐Day Activity in Young Men and Women

Background : Only few data are available on reproducibility over time in healthy young men and women and the corresponding gender‐related changes of heart rate variability (HRV) measurements. Methods : We studied temporal and spectral HRV indices obtained from 24‐hour Holter recordings in 32 healthy volunteers (14 men and 18 women, mean age 29 ± 3 years) during 2 days of their usual all‐day activity. Results : Time‐domain measures and the spectral low‐frequency (LF) and high‐frequency (HF) components as well as the LF/HF ratio were comparable on both test days. Significantly higher values on test day 2 were observed only for the spectral very‐low‐frequency (VLF) component and for the resulting total power. Compared to men, women had higher day‐ and nighttime vagus‐associated HRV indices, including root mean square of successive differences (RMSSD), pNN50 (NN50 count divided by the total number of all NN intervals), and HF power, and lower day‐ and nighttime VLF and LF power with lower LF/HF ratio and total power. Conclusions : Temporal indices and the LF and HF spectral HRV measures are reproducible over usual all‐day activity in young healthy subjects. Young women have higher day‐and nighttime vagal tone than men with similar age range.     

Studies of Filipino patients with systemic lupus erythematosus: autoantibody profile of first-degree relatives

This study surveyed the frequency of autoantibodies among un-affected first-degree relatives (FDRs) of Filipino systemic lupus erythematosus (SLE) patients compared with healthy un-related Filipino controls. The sensitivity, specificity and predictive value of the autoantibodies for SLE diagnosis were also assessed in this Filipino cohort. Filipino patients included in the University of Santo Tomas (UST) Lupus Database and un-affected FDRs were recruited. Healthy controls included those with no known personal or family history of autoimmune disease. The following autoantibodies were tested in all subjects: anti-nuclear antibody (ANA), anti-dsDNA, anti-Ro/SSA, anti-chromatin, anti-thyroid microsome, and anti-cardiolipin antibodies. Participants included 232 SLE patients, 546 FDRs, and 221 healthy controls. Median age of patients was 27 (range 8-66) years with median disease duration of 27.5 (range 1-292) months. Median age of FDRs was 42.0 (range 5-87) years. Compared with healthy controls, there were significantly more FDRs with positive ANA at titers 1?:?40 to 1?:?160 (p?相似文献   

CO2 elimination and airway opening pressure during high frequency oscillation in dogs

CO2 elimination (VCO2) and pressure at the airway opening (Pao) were measured over a wide range of frequencies (f) (5-40 Hz) and tidal volumes (VT) (1-45 ml) during high frequency oscillatory ventilation (HFO) in 11 anesthetized, paralyzed dogs. CO2 elimination was found to depend primarily on the product off and VT which is consistent with theoretical predictions of gas exchange by augmented dispersion. Airway opening pressures during HFO were frequency dependent. At frequencies near 5 Hz Pao was lower, while at frequencies above 5 Hz Pao was higher than Pao during conventional mechanical ventilation (12 cm H2O). The minimum Pao (5 cm H2O) achieved while maintaining VCO2 equivalent to normal metabolic CO2 production occurred when VT was near that of the dead space volume and frequency was near 5 Hz. At lower VT, higher frequencies were required to maintain VCO2 and this increased frequency resulted in an increase in Pao amplitude (10-15 cm H2O).     

A New Wide-Band Double-Negative Metamaterial for C- and S-Band Applications

A new design and analysis of a wide-band double-negative metamaterial, considering a frequency range of 0.5 to 7 GHz, is presented in this paper. Four different unit cells with varying design parameters are analyzed to evaluate the effects of the unit-cell size on the resonance frequencies of the metamaterial. Moreover, open and interconnected 2 × 2 array structures of unit cells are analyzed. The finite-difference time-domain (FDTD) method, based on the Computer Simulation Technology (CST) Microwave Studio, is utilized in the majority of this investigation. The experimental portion of the study was performed in a semi-anechoic chamber. Good agreement is observed between the simulated and measured S parameters of the developed unit cell and array. The designed unit cell exhibits negative permittivity and permeability simultaneously at S-band (2.95 GHz to 4.00 GHz) microwave frequencies. In addition, the designed unit cell can also operate as a double-negative medium throughout the C band (4.00 GHz to 4.95 GHz and 5.00 GHz to 5.57 GHz). At a number of other frequencies, it exhibits a single negative value. The two array configurations cause a slight shift in the resonance frequencies of the metamaterial and hence lead to a slight shift of the single- and double-negative frequency ranges of the metamaterial.     

Higher heart rate variability of smokers after acute myocardial infarction

Although cigarette smoking is known to be a strong risk factor for the development of coronary artery disease, several large clinical studies have demonstrated that current smokers had a favorable prognosis compared to nonsmokers after myocardial infarction. This study sought to evaluate the effect of smoking status on heart rate variability after onset of acute myocardial infarction. We studied 52 patients (34 smokers, 18 nonsmokers) with a first myocardial infarction within 24 h of onset. We recorded 24-h ambulatory ECG to calculate very low frequency power (VLF), low frequency power (LF) and high frequency power (HF) 14 days after onset. Although smokers had a tendency to be younger than nonsmokers (mean age 57 versus 62, P = 0.0812), clinical characteristics were not statistically different between smokers and nonsmokers. After adjustment for age, left ventricular ejection fraction, history of diabetes, acute revascularization and use of beta-blockers, VLF (P = 0.0183) of smokers 14 days after onset was significantly higher than for nonsmokers. In conclusion, although smoking reduces heart rate variability in the general population, higher heart rate variability was observed in smokers than nonsmokers after acute myocardial infarction under the condition of smoking cessation.     

Studies on the flow and distribution of leukocytes in mesentery microcirculation of rats

Subjectheadingsmicrocirculation;leukocyte;leukocyte--endotheliuminteraction;mesenteryINTRODUCTIONLeukocyte-endotheliuminteraction(LEI)existsinmanypathophysiologicalprocesses,suchasinflammation,burns,tumorandshockll'Zj.Intherecenttwodecades,quantitativestudiesontheinteractionofleukocyte-endotheliumhavebeencarriedoutandthechangeoftheflowanddistributionof.leukocytesisthebasisfortheabnormalincreaseofLEI[3--5].HighlevelLEIwouldbringabouttheblockageofbloodvesselsanddecreaseofbloodperfusion"…     

Identification of transducer defect in respiratory impedance measurements by forced random noise. Correction of experimental data

The measurement of respiratory impedance by means of the forced oscillations technique depends on the frequency response of various measurement devices: pressure transducers, flowmeter, filters, etc. In the range of frequencies where measurements were done (0--100 Hz) it is difficult to have the same response (amplitude and phase) for mouth pressure and flow transducers. It is possible to identify the relative frequency response of both devices. This can be done by comparison of measurements made on a well-defined mechanical system with a theoretical model representing this system. The method also avoids separate frequency calibrations of pressure and flow. Its validity depends only on the accuracy of the model of impedance of the standard system used.     

Longitudinal analysis of heart rate variability in chronic hypertensive pregnancy.

In the US, it is currently estimated that 3% of pregnant women have chronic hypertension, or more than 100,000 pregnant women each year. The aim of our study was to investigate the adaptation of autonomic control during pregnancy based on heart rate variability analysis and to determine whether chronic hypertension during pregnancy has an impact on this adaptation. Sixteen pregnant women with chronic hypertension (CH group; mean age, 30 years; range, 25-33 years) and 35 healthy pregnant women serving as controls (CON group; mean age, 28 years; range, 24-30 years) were recruited for this longitudinal study. Beginning at the 20th week of pregnancy, the women were monitored every 4th week until delivery. For the analysis of heart rate variability, Portapres signals (200 Hz) were recorded for 30 min under resting conditions. Women in the CH group had significantly elevated blood pressure compared to controls (CON, 111 mmHg [105-132]; CH, 140 mmHg [132-148]; p<0.001). An increased heart rate was found in both groups during the second half of pregnancy. Consequently, decreased heart rate variability was observed, but was more pronounced in the CON group. There was a shift in the frequency bands indicated by an elevation of the low-to-high frequency ratio (LF/HF) in both groups due to a decrease in HF, and thus a significant increase in LFn (LF power in normalized units). However, VLF (power of very low frequency range) increased exclusively in the CON pregnancies. Our data showed no significant difference in heart rate variability between the subjects of the CH and CON groups. Longitudinal variations were detectable in normal pregnancies and also, albeit to a lesser degree, in chronic hypertensive pregnant women. Thus, our data indicate that patients with long-term hypertension are still able to respond to the physiological changes occurring during pregnancy.