This study was undertaken to in vestigate the effects of lower body positive pressure (LBPP) on cardiovascular responses during a 15-min walking trial in young (22.1±0.4 years) and elderly women (67.8±1.1 years). The application of 20 mm Hg LBPP reduced ground reaction forces by 31.2±0.5 kgw in both groups. We hypothesized that cardiovascular responses to LBPP during walking were different between the young and elderly subjects. Applying 20 mm Hg of LBPP increased diastolic and mean blood pressure but not systolic blood pressure in both groups. LBPP- induced reduction in heart rate (HR) occurred more quickly in the young group compared to the elderly group (p<0.05). Applying LBPP also decreased double product (systolic blood pressure x HR) in both groups, suggesting that LBPP reduces myocardial oxygen consumption during exercise. These results suggest that heart rate responses to LBPP during exercise vary with increasing age., T. Sota ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
Diabetes mellitus (DM) has been known for many years to be associated with poor cardiovascular prognosis. Due to the sensitive neuropathy, the coronary artery disease in diabetic patients is frequently asymptomatic. Also twelve leads resting ECG can be within normal limits even in an advanced stage of coronary artery disease. Therefore in addition to the standard ECG other electrocardiographic procedures started to be studied in order to find some typical signs of myocardial damages caused by DM. Repeatedly reported results showed in DM patients without cardiovascular complications the tachycardia, shortening of the QRS and QT intervals, increase of the dispersion of QT interval, decreased amplitudes of depolarization waves, shortened activation time of ventricular myocardium and a flattening of T waves confirmed by the lower value of maximum and minimum in repolarization body surface isopotential maps. Most of these changes are even more pronounced in patients with cardiac autonomic neuropathy. Comparison with similar ECG changes in other diseases suggests that the electrocardiographic changes in DM patients are not specific and that they are particularly caused by an increased tone of the sympathetic nervous system what was indirectly confirmed by the heart rate variability findings in these patients., O. Kittnar., and Obsahuje bibliografii
b1_The aim of our study was to compare the responses of heart rate variability (HRV) with two di fferent types of hormonal substitution therapy (HT) in post-menopausal women (cross-sectional study) and to reveal an effect of HT shortly after beginning of its administration (f ollow-up study). To elucidate the influence of menopause and effects of different protocols of a HT on autonomic control of heart rate, we evaluated the heart rate variability (HRV) in 5 groups: premenopausal women (n=140), postmenopausal women without HT (n=360), women on HT with conjugated estrogen only (n =168), women on continuous combined estrogen-progesterone HT (n=117), and men (n=140). Frequency-domain of short-term stationary R-R intervals was performed to evaluate the total variance, low frequency power (LF; 0.04-0.15 Hz), high freque ncy power (HF; 0.15-0.40 Hz), portion of low frequency power (LF%) and ratio of LF to HF (LF/HF). Significantly lower portion of the LF was found in premenopausal women [46.9 (±2.7) nu] when compared to untreated postmenopausal wome n [54.3 (±2.9) nu] and men [55.2 (±3.0) nu]. Treatment by estrogen only was proved to decrease the LF% [40.1 (±2.1) nu] while no effect on HRV was observed in women treated with combination of estrogen and progesterone [57.2 (±3.1) nu]. Also the HF was lower in postmenopausal wome n [4.16 (±0.16) ms 2 ] than in premenopausal women [4.79 (±0.22) ms 2 ] and women treated with estrogen only [4.98 (±0.25) ms 2 ] while in women treated with combined hormonal therapy the average value [3.99 (±0.21) ms 2 ] did not significantly differ from that of untreated postmenopausal women. The follow-up study also proved increase of high frequency power already after two months of estrogen substitution therapy [4.86 (±0.14) ms 2 vs. 4.19 (±0.15) ms 2 ]., b2_These results suggest that hi gher vagal modulation of heart rate that seems typical for younger women becomes after menopause similar to that of men. We also proved a positive shift of HRV parameters toward more beneficial values as for a cardiovascular risk in postmenopausal women treated with estrogens but not in those treated by combined estrogen - progesterone substitution therapy., S.-G. Yang, M. Mlček, O. Kittnar., and Obsahuje bibliografii a bibliografické odkazy
The kinetics of post-exercise heart rate (HR) and oxygen consumption (EPOC) was studied in 10 elite cyclists subjected to four laboratory cycle ergometer maximal exercises lasting 30, 90, 180 or 360 s. Heart rate and oxygen uptake (VO2) were recorded over a period of 6 min after the exercise. By applying the logit transformation to the recorded variables and relating them to the decimal logarithm of the recovery time, uniform single-phase courses of changes were shown for both variables in all subjects and exercises. This enabled computing half-recovery times (t½) for both variables. Half-time for VO2 negatively correlated with square root of exercise duration (within-subject r=-0.629, p<0.001), the total post-exercise oxygen uptake till t½ was thus constant irrespectively of exercise intensity. The method is simple and enables reliable comparisons of various modes of exercise with respect to the rate of recovery., R. Stupnicki ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
The objective was to establish whether an intravascular volume increase leads to a heart rate (HR) increase without increased sympathetic tonus. HR changes at rest and at deep breathing (6/min - simulated increase of atrial filling pressure) were measured in patients after heart transplantation. Evaluation of dependency of HR changes on breathing depth was done through a new time series methodology. The data was evaluated through graphs displaying a significant increase in the graph area at deep breathing, when compared with breathing at rest (p < 0.01). We presume that an increase in HR corresponds to increased intravascular volume and malfunctioning kidneys., M. Souček, T. Kára, P. Jurák, J. Halámek, L. Špinarová, J. Meluzím, J. Toman, I. Řiháček, J. Šumbera, P. Fráňa., and Obsahuje bibliografii
The aim of the study was to evaluate short-term heart rate variability (HRV) as an index of cardiac autonomic control in rats with lipopolysaccharide (LPS)-induced endotoxemia. Animals were injected intraperitoneally with LPS (100 μg/kg b.w.) and control group with an equivalent volume of saline. ECG recordings were done before (base) and 60, 120, 180, 240 and 300 min after LPS or saline administration. HRV magnitude was quantified by time and frequency-domain analysis (mean RR interval, SDRR, RMSSD, spectral powers in low (LF) and high frequency (HF) bands. Heart tissue homogenates and plasma were analyzed to determine interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-α) and oxidative stress level (TBARS). Administration of lipopolysaccharide was followed by continuous rise in colonic body temperature compared to saline-treated controls. Endotoxemia in rats was accompanied by significant decrease in HRV spectral activity in high-frequency range at maximal body temperature (logHFpower: 1.2±0.5 vs. 1.9± 0.6 ms2, P<0.01). Increased IL-6 was found in heart tissue homogenates of LPS rats (8.0±0.6 vs. 26.4±4.8 pg/ml, (P<0.05). In conclusions, reduced HRV in HF band may indicate a decreased parasympathetic activity in LPS-induced endotoxemia as basic characteristics of altered cardiac control during response to endotoxemia., I. Zila, D. Mokra, J. Kopincova, M. Kolomaznik, M. Javorka, A. Calkovska., and Obsahuje bibliografii
Heart rate (HR) and heart rate variability (HRV) in newborns is influenced by genetic determinants, gestational and postnatal age, and other variables. Premature infants have a reduced HRV. In neonatal HRV evaluated by spectral analysis, a dominant activity can be found in low frequency (LF) band (combined parasympathetic and sympathetic component). During the first postnatal days the activity in the high frequency (HF) band (parasympat hetic component) rises, together with an increase in LF band and total HRV. Hypotrophy in newborn can cause less mature autonomic cardiac control with a higher contribution of sympathetic activity to HRV as demonstrated by sequence plot analysis. During quiet sleep (QS) in newborns HF oscillations increase - a phenomenon less expressed or missing in premature infants. In active sleep (AS), HRV is enhanced in contrast to reduced activity in HF band due to the rise of spectral activity in LF band. Comparison of the HR and HRV in newborns born by physiological vaginal delivery, without (VD) and with epidural anesthesia (EDA) and via sectio cesarea (SC) showed no significant differences in HR and in HRV time domain parameters. Analysis in the frequency domain re vealed, that the lowest sympathetic activity in chronotropic cardiac chronotropic regulation is in the VD group. Different neonatal pathological states can be associated with a reduction of HRV and an improvement in the health conditions is followed by ch anges in HRV what can be use as a possible prognostic marker. Examination of heart rate variability in neonatology can provide information on the maturity of the cardiac chronotropic regulation in early postnatal life, on postnatal adaptation and in pathological conditions about the potential dysregulation of cardiac function in newborns, especially in preterm infants., K. Javorka, Z. Lehotska, M. Kozar, Z. Uhrikova, B. Kolarovszki, M. Javorka, M. Zibolen., and Obsahuje bibliografii
Diabetes mellitus is associated with a variety of cardiovascular complications including impaired cardiac muscle function. The effects of insulin treatment on heart rate, body temperature and physical activity in the alloxan (ALX)-induced diabetic rat were investigated using in vivo biotelemetry techniques. The electrocardiogram, physical activity and body temperature were recorded in vivo with a biotelemetry sy stem for 10 days before ALX treatment, for 20 days following administration of ALX (120 mg/kg) and thereafter, for 15 days whilst rats received daily insulin. Heart rate declined rapi dly after administration of ALX. Pre-ALX heart rate was 321 ± 9 beats per minute, falling to 285 ± 12 beats per minute 15-20 days after ALX and recovering to 331±10 beats per minute 5-10 days after commencement of insulin. Heart rate variabilit y declined and PQ, QRS and QT intervals were prolonged after administration of ALX. Physical activity and body temperature declined after administration of ALX. Pre-ALX body temperature was 37.6 ± 0.1 °C, falling to 37.3 ± 0.1 °C 15-20 days after ALX an d recovering to 37.8±0.1 °C 5-10 days after commencement insulin. ALX-induced diabetes is associated with disturbances in heart rhythm, physical activity and body temperature that are variously affected during insulin treatment., F. C. Howarth ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
The aim of the study was to assess the association between promoter polymorphism [A(-596)G] in interleukin-6 gene and office systolic and diastolic blood pressures, and the heart rate (HR) in apparently healthy Czech subjects. Furthermore, we evaluated the possible influence of gender, BMI and smoking on these supposed associations. An age-matched (40-50 years) and gender-matched (F/M=81/89) sample of apparently healthy Czech subjects (n=170, F/M=81/89) without hypertension, other cardiovascular diseases or diabetes was examined. The A(-596)G Il-6 gene polymorphism was detected by the PCR method. No differences in genotype distribution and/or allelic frequency was found between groups with lower systolic blood pressure (£ 122 mm Hg) and higher systolic blood pressure (> 122 mm Hg). Similarly, no differences in the IL-6 polymorphism were found between lower (£ 86 mm Hg) and higher (> 86 mm Hg) diastolic blood pressure groups. However, we proved a significant increase of genotypes AG+GG as well as the allele (-596)G in higher (>78 beats/min) heart rate group. The genotypes AG+GG represent significantly higher relative risk for higher HR frequency, especially in women. Among lean persons with a low heart rate frequency, fewer AG+GG genotypes were determined than among any other subjects. The genotypes AG+GG are more frequent in non-smoking persons with higher HR compared to non-smoking subjects with lower HR, especially in women. Gender, BMI and smoking substantially modify the distribution of A(-596)G Il-6 gene polymorphism in apparently healthy persons with lower or higher heart rate., A. Vašků, M. Souček, M. Goldbergová, J. Vácha., and Obsahuje bibliografii
Whole-body vibration (WBV) is a new exercise method, with good acceptance among sedentary subjects. The metabolic response to WBV has not been well documented. Three groups of male subjects, inactive (SED), endurance (END) and strength trained (SPRINT) underwent a session of side-alternating WBV composed of three 3-min exercises (isometric half-squat, dynamic squat, dynamic squat with added load), and repeated at three frequencies (20, 26 and 32 Hz). VO2, heart rate and Borg scale were monitored. Twenty-seven healthy young subjects (10 SED, 8 SPRINT and 9 END) were included. When expressed in % of their maximal value recorded in a treadmill test, both the peak oxygen consumption (VO2) and heart rate (HR) attained during WBV were greatest in the SED, compared to the other two groups (VO2: 59.3 % in SED vs 50.8 % in SPRINT and 48.0 % in END, p<0.01; HR 82.7 % in SED vs 80.4 % in SPRINT and 72.4 % in END, p<0.05). In conclusions, the heart rate and metabolic response to WBV differs according to fitness level and type, exercise type and vibration frequency. In SED, WBV can elicit sufficient cardiovascular response to benefit overall fitness and thus be a potentially useful modality for the reduction of cardiovascular risk., B. Gojanovic, F. Feihl, G. Gremion, B. Waeber., and Obsahuje bibliografii