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- Jensen-Urstad, K, et al.
(författare)
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Heart rate variability in healthy subjects is related to age and gender.
- 1997
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Ingår i: Acta Physiologica Scandinavica. - 0001-6772 .- 1365-201X. ; 160:3, s. 235-41
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Tidskriftsartikel (refereegranskat)abstract
- The effects of age and gender on heart rate variability as measured by spectral and time domain analysis of 24 h ECG recordings were evaluated in 101 healthy subjects, 49 men and 52 women (20-69 years of age). In the frequency domain, total power, very low-frequency power, low-frequency power and high-frequency power were negatively correlated to age (P < 0.001 for all variables). Total power decreased by 30% between 20-29 and 60-69 years of age. In the time domain, SDNN-index, the mean of the standard deviations of all normal R-R intervals for all 5 min segments of a 24 h ECG recording, was negatively correlated to age (P < 0.001). Total power, very low-frequency power, low-frequency power and the low-frequency/high-frequency ratio were lower in women (P < 0.05, P < 0.05, P < 0.01 and P < 0.01), although the absolute differences were much smaller than for age. There was a pronounced circadian variation; at night total power increased in all age groups (P < 0.01). The results show that age, and to a lesser degree gender, are important determinants of heart rate variability in healthy subjects. Heart rate variability is a valuable tool for risk stratification in cardiovascular disease, but the physiological effects of ageing, with diminishing heart rate variability in older age groups, must also be taken into account.
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| 2. |
- Jensen-Urstad, K, et al.
(författare)
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Pronounced resting bradycardia in male elite runners is associated with high heart rate variability.
- 1997
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Ingår i: Scandinavian Journal of Medicine and Science in Sports. - : Wiley. - 0905-7188 .- 1600-0838. ; 7:5, s. 274-8
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Tidskriftsartikel (refereegranskat)abstract
- Forty-eight hour Holter monitoring was undertaken of 16 male elite middle- and long-distance runners, age 25 +/- 3 years, with peak oxygen uptake 4.83 +/- 0.43 1 O2/min or 73.0 +/- 3.9 ml O2/kg/min. The athletes had pronounced bradycardia during the night-time, with heart rate calculated from four RR intervals < 30 beats/min in five runners. Twelve of 16 runners had RR intervals > 2 s. Of those, 10 runners had sinus pauses exceeding 2 s, the longest being 3.06 s. Three runners had AV block II, two with Mobitz type 1, and one with both Mobitz type 1 and 2. Autonomic function was estimated by time domain and power spectral analysis of heart rate variability. The runners were compared with a control group of 13 sedentary or moderately active subjects. The runners had a mean of 14 b.p.m. lower heart rate at night than the controls. The runners had higher heart rate variability in all spectral bands. In the time domain pNN50 and rMSSD, which are considered to reflect strongly vagal tone, were markedly higher in the runners than the controls. The findings suggest that an increased parasympathetic tone might at least partly explain the pronounced resting sinus bradycardias found in endurance-trained runners.
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| 3. |
- Eneroth, E, et al.
(författare)
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24-hour ECG frequency-domain measures in preeclamptic and healthy pregnant women during and after pregnancy.
- 1999
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Ingår i: Hypertension in Pregnancy. - : Informa UK Limited. - 1064-1955 .- 1525-6065. ; 18:1, s. 1-9
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: The aim of the present study was to evaluate the autonomic balance in women with preeclampsia and in healthy women during and after pregnancy by means of a 24-h ECG Holter recording combined with power spectral analysis. METHODS: Fifteen preeclamptic and 15 healthy women underwent 24-h Holter monitoring in the 32nd-36th week of gestation and 3-6 months postpartum. The power spectrum of the maternal electrocardiogram was analyzed with an autoregressive algorithm. MAIN OUTCOME MEASURES: The power spectrum contains two major components: a low-frequency peak, primarily attributed to sympathetic tone, and a high-frequency peak, reflecting vagal tone. RESULTS: The power spectrum of maternal heart rate variability did not differ between preeclamptic and normal women during pregnancy. After delivery, the amplitude of all components became significantly higher than those during pregnancy, with one exception: the high-frequency component in the patients who had been preeclamptic. In a comparison of the two groups, the high-frequency component after delivery was significantly lower in women who had preeclampsia than in normal healthy women (p = 0.03). CONCLUSIONS: During pregnancy, the power spectrum is reduced and cannot be used to distinguish between patients with preeclampsia and normal healthy women. Three to 6 months after delivery, the high-frequency component is still reduced in the preeclamptic group of women. This indicates an impaired vagal modulation even in the nonpregnant state in this group of women, unlike those who had a normotensive pregnancy.
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| 4. |
- Quintana, M, et al.
(författare)
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Heart rate variability as a means of assessing prognosis after acute myocardial infarction. A 3-year follow-up study.
- 1997
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Ingår i: European Heart Journal. - : Oxford University Press (OUP). - 0195-668X .- 1522-9645. ; 18:5, s. 789-97
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: The present study evaluated the prognostic value of heart rate variability after acute myocardial infarction in comparison with other known risk factors. The cut-off points that maximized the hazards ratio were also explored. PATIENTS AND METHODS: Heart rate variability was assessed with 24 h ambulatory electrocardiography in 74 patients with acute myocardial infarction, 4 +/- 2 days after hospital admission and in 24 healthy controls. Patients were followed for 36 +/- 15 months. RESULTS: During follow-up, 18 patients died, nine suffered a non-fatal infarction and 20 underwent revascularization procedures. Heart rate variability was higher in survivors than in non-survivors (P = 0.005). This difference was found at higher statistical levels when comparing non-survivors vs controls (P = 0.0002). A similar statistically significant difference was also found between survivors vs controls (P = 0.04). Patients suffering non-fatal infarction and cardiac events (defined as death, non-fatal infarction or revascularization) had a lower heart rate variability than those without (P = 0.03 and P = 0.03, respectively). With multivariate regression analysis, decreased heart rate variability independently predicted mortality and death or non-fatal infarction. The presence of a left ventricular ejection fraction < 40% and a history of systemic hypertension were, however, stronger predictors. The cut-off points that maximized the hazards ratio using the Cox model differed from those reported by others. CONCLUSION: Decreased heart rate variability independently predicted poor prognosis after myocardial infarction. However, the cut-off points that should be used in clinical practice are still a matter for further investigation.
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