In heart failure (HF), exercise training programmes (ETPs) are a well-recognized intervention to ... more In heart failure (HF), exercise training programmes (ETPs) are a well-recognized intervention to improve symptoms, but are still poorly implemented. The Heart Failure Association promoted a survey to investigate whether and how cardiac centres in Europe are using ETPs in their HF patients. The co-ordinators of the HF working groups of the countries affiliated to the European Society of Cardiology (ESC) distributed and promoted the 12-item web-based questionnaire in the key cardiac centres of their countries. Forty-one country co-ordinators out of the 46 contacted replied to our questionnaire (89%). This accounted for 170 cardiac centres, responsible for 77 214 HF patients. The majority of the participating centres (82%) were general cardiology units and the rest were specialized rehabilitation units or local health centres. Sixty-seven (40%) centres [responsible for 36 385 (48%) patients] did not implement an ETP. This was mainly attributed to the lack of resources (25%), largely due to lack of staff or lack of financial provision. The lack of a national or local pathway for such a programme was the reason in 13% of the cases, and in 12% the perceived lack of evidence on safety or benefit was cited. When implemented, an ETP was proposed to all HF patients in only 55% of the centres, with restriction according to severity or aetiology. With respect to previous surveys, there is evidence of increased availability of ETPs in HF in Europe, although too many patients are still denied a highly recommended therapy, mainly due to lack of resources or logistics.
1. Heart rate variability can be used to evaluate autonomic balance, but it is unclear how inotro... more 1. Heart rate variability can be used to evaluate autonomic balance, but it is unclear how inotropic therapy may affect the findings. The aim of the study was to assess whether heart rate variability can differentiate between sympathetic stimulation induced by inotrope infusion or by physical exercise. 2. Ten patients with chronic heart failure (64.3 +/- 5.4 years of age) underwent four dobutamine infusions (8-min steps of 5 micrograms min-1 kg-1) and four supine bicycle exercise tests (5-min steps of 25 W). Plasma noradrenaline was evaluated, as well as the SD of R-R intervals, together with low-frequency (0.03-0.14 Hz) and high-frequency (0.15-0.4 Hz) components of heart rate variability using autoregressive spectral analysis. 3. Exercise and inotrope infusion produced similar changes in heart rate variability. An exercise load of 50 W and a dobutamine infusion of 15 micrograms min-1 kg-1 gave the following results respectively: heart rate, 120.3 +/- 3.0 beats/min versus 110.2 +/-...
ABSTRACT 1. In patients with chronic heart failure, heart rate variability is reduced with relati... more ABSTRACT 1. In patients with chronic heart failure, heart rate variability is reduced with relative preservation of very-low-frequency power (< 0.04 Hz). Heart rate variability has been measured without acceptable information on its stability and the optimal recording periods for enhancing this reproducibility. 2. To this aim and to establish the optimal length of recording for the evaluation of the very-low-frequency power, we analysed 40, 20, 10 and 5 min ECG recordings obtained on two separate occasions in 16 patients with chronic heart failure. The repeatability coefficient and the variation coefficient were calculated for the heart rate variability parameters, in the time-domain (mean RR, SDRR and pNN50), and in the frequency-domain: very low frequency (< 0.04 Hz), low frequency (0.04-0.15 Hz), high frequency (0.15-0.40 Hz), total power (0-0.5 Hz). 3. Mean RR remained virtually identical over time (variation coefficient 8%). The reproducibility of time-domain (variation coefficient 25-139%) and of spectral measures (variation coefficient 45-111%) was very low. The stability of the heart rate variability parameters was only apparently improved after square root and after log transformation. 4. Very-low-frequency values derived from 5 and 10 min intervals were significantly lower than those calculated from 40 and 20 min intervals (P < 0.005). Discrete very-low-frequency peaks were detected in 11 out of 16 patients on the first 40, 20 and 10 min recording, but only in seven out of 16 when 5 min segments were analysed. 5. The reproducibility of both time or frequency-domain measures of heart rate variability in patients with chronic heart failure may vary significantly. Square root or log-transformed parameters may be considered rather than absolute units in studies assessing the influence of management on heart rate variability profile. Recordings of at least 20 min in stable, controlled conditions are to be recommended to optimize signal acquisition in patients with chronic heart failure, if very-low-frequency power in particular is to be studied.
To evaluate whether beta-blocker treatment could enhance the effect of a mild physical training p... more To evaluate whether beta-blocker treatment could enhance the effect of a mild physical training programme upon blood pressure. In 12 hypertensive subjects (mean age: 40.3 years) a prospective randomized Latin square-design trial was performed with three treatments: physical training and placebo tablets; atenolol 50 mg once a day and inactivity; and physical training and atenolol 50 mg once a day. Training significantly increased maximal ventilatory oxygen consumption (VO2MAX), and there was a decrease in ambulatory diastolic blood pressure (DBP) which did not reach statistical significance. Atenolol alone significantly reduced ambulatory systolic blood pressure (SBP) and DBP. Atenolol alone did not reduce VO2MAX. The combination of training and atenolol resulted in an increase in VO2MAX compared with atenolol alone, but no additional significant fall in blood pressure. Atenolol did not enhance the effect of physical training upon blood pressure and had little if any effect upon the training-induced increase in exercise tolerance.
The sequence method is widely used as a simple, non-invasive measure of baroreflex sensitivity (B... more The sequence method is widely used as a simple, non-invasive measure of baroreflex sensitivity (BRS). This technique, originally described in anaesthetized cats, has been transferred virtually unchanged to humans, without evidence that the optimal values in cats are the same as those in patients with cardiovascular disease. To study the effect of altering the components of the sequence method on the measured BRS in patients with chronic heart failure (CHF) and in normal individuals. Eighty patients with CHF [aged 62 +/- 12 years (mean +/- SD)] and 40 normal control individuals [aged 38 +/- 15 years (mean +/- SD)] underwent measurement of heart rate and non-invasive blood pressure. Altering only the shift between blood pressure and R-R interval and the required correlation coefficient of the regression line had no effect on the value of BRS, but had a significant effect on the number of valid sequences. Alteration of the blood pressure or R-R interval thresholds, however, affected not only the number of valid sequences, but also the value of BRS in both groups. In normal controls, agreement with the bolus phenylephrine method was improved by increasing the blood pressure threshold, although this led to a reduction in the number of valid sequences. In patients with CHF, agreement was optimized by decreasing both the blood pressure and R-R interval thresholds. This also had the effect of increasing the number of valid sequences. Changes should be made to this technique, to optimize its validity in conscious humans, particularly when applied to patients with attenuated BRS.
It is not known whether the temporal relationship between blood pressure (BP) and RR interval is ... more It is not known whether the temporal relationship between blood pressure (BP) and RR interval is modulated by the same mechanisms in normal controls and patients with chronic heart failure (CHF). We investigated this under conditions of controlled slow breathing. Fifty patients with CHF and 17 age-matched normals underwent recordings of BP and RR interval during 0.1 Hz controlled breathing. Fourier analysis was used to determine the phase relationships between the oscillations in respiration, BP and RR interval. There was no significant difference between patients and normals in the distribution of phase angle between respiration and BP (P=0.06) or between respiration and RR interval (P=0.21). There was, however, a significant difference in the phase relationship between BP and RR interval (P=0.03): in normals, BP led RR interval by a mean phase angle of 48.4 degrees (S.D. 16.8 degrees ). In patients with CHF, the distribution of phase difference was much wider [34.4 degrees (S.D. 62.8 degrees )]. The source of this wide distribution was patients with attenuated baroreflex sensitivity (BRS), with those with preserved BRS showing a relationship between BP and RR interval similar to the normal group. During controlled respiration, normal subjects exhibit a stereotyped relationship between oscillations in BP and RR interval, which is mediated by the baroreflex. This relationship is maintained in those patients with CHF who have a preserved BRS. In contrast, patients with an attenuated BRS show a wide distribution in the relationship between BP and RR interval ranging from completely in phase, to anti-phase. This may have important implications for the measurement and interpretation of BRS in patient groups where BRS is weak.
In heart failure (HF), exercise training programmes (ETPs) are a well-recognized intervention to ... more In heart failure (HF), exercise training programmes (ETPs) are a well-recognized intervention to improve symptoms, but are still poorly implemented. The Heart Failure Association promoted a survey to investigate whether and how cardiac centres in Europe are using ETPs in their HF patients. The co-ordinators of the HF working groups of the countries affiliated to the European Society of Cardiology (ESC) distributed and promoted the 12-item web-based questionnaire in the key cardiac centres of their countries. Forty-one country co-ordinators out of the 46 contacted replied to our questionnaire (89%). This accounted for 170 cardiac centres, responsible for 77 214 HF patients. The majority of the participating centres (82%) were general cardiology units and the rest were specialized rehabilitation units or local health centres. Sixty-seven (40%) centres [responsible for 36 385 (48%) patients] did not implement an ETP. This was mainly attributed to the lack of resources (25%), largely due to lack of staff or lack of financial provision. The lack of a national or local pathway for such a programme was the reason in 13% of the cases, and in 12% the perceived lack of evidence on safety or benefit was cited. When implemented, an ETP was proposed to all HF patients in only 55% of the centres, with restriction according to severity or aetiology. With respect to previous surveys, there is evidence of increased availability of ETPs in HF in Europe, although too many patients are still denied a highly recommended therapy, mainly due to lack of resources or logistics.
1. Heart rate variability can be used to evaluate autonomic balance, but it is unclear how inotro... more 1. Heart rate variability can be used to evaluate autonomic balance, but it is unclear how inotropic therapy may affect the findings. The aim of the study was to assess whether heart rate variability can differentiate between sympathetic stimulation induced by inotrope infusion or by physical exercise. 2. Ten patients with chronic heart failure (64.3 +/- 5.4 years of age) underwent four dobutamine infusions (8-min steps of 5 micrograms min-1 kg-1) and four supine bicycle exercise tests (5-min steps of 25 W). Plasma noradrenaline was evaluated, as well as the SD of R-R intervals, together with low-frequency (0.03-0.14 Hz) and high-frequency (0.15-0.4 Hz) components of heart rate variability using autoregressive spectral analysis. 3. Exercise and inotrope infusion produced similar changes in heart rate variability. An exercise load of 50 W and a dobutamine infusion of 15 micrograms min-1 kg-1 gave the following results respectively: heart rate, 120.3 +/- 3.0 beats/min versus 110.2 +/-...
ABSTRACT 1. In patients with chronic heart failure, heart rate variability is reduced with relati... more ABSTRACT 1. In patients with chronic heart failure, heart rate variability is reduced with relative preservation of very-low-frequency power (< 0.04 Hz). Heart rate variability has been measured without acceptable information on its stability and the optimal recording periods for enhancing this reproducibility. 2. To this aim and to establish the optimal length of recording for the evaluation of the very-low-frequency power, we analysed 40, 20, 10 and 5 min ECG recordings obtained on two separate occasions in 16 patients with chronic heart failure. The repeatability coefficient and the variation coefficient were calculated for the heart rate variability parameters, in the time-domain (mean RR, SDRR and pNN50), and in the frequency-domain: very low frequency (< 0.04 Hz), low frequency (0.04-0.15 Hz), high frequency (0.15-0.40 Hz), total power (0-0.5 Hz). 3. Mean RR remained virtually identical over time (variation coefficient 8%). The reproducibility of time-domain (variation coefficient 25-139%) and of spectral measures (variation coefficient 45-111%) was very low. The stability of the heart rate variability parameters was only apparently improved after square root and after log transformation. 4. Very-low-frequency values derived from 5 and 10 min intervals were significantly lower than those calculated from 40 and 20 min intervals (P < 0.005). Discrete very-low-frequency peaks were detected in 11 out of 16 patients on the first 40, 20 and 10 min recording, but only in seven out of 16 when 5 min segments were analysed. 5. The reproducibility of both time or frequency-domain measures of heart rate variability in patients with chronic heart failure may vary significantly. Square root or log-transformed parameters may be considered rather than absolute units in studies assessing the influence of management on heart rate variability profile. Recordings of at least 20 min in stable, controlled conditions are to be recommended to optimize signal acquisition in patients with chronic heart failure, if very-low-frequency power in particular is to be studied.
To evaluate whether beta-blocker treatment could enhance the effect of a mild physical training p... more To evaluate whether beta-blocker treatment could enhance the effect of a mild physical training programme upon blood pressure. In 12 hypertensive subjects (mean age: 40.3 years) a prospective randomized Latin square-design trial was performed with three treatments: physical training and placebo tablets; atenolol 50 mg once a day and inactivity; and physical training and atenolol 50 mg once a day. Training significantly increased maximal ventilatory oxygen consumption (VO2MAX), and there was a decrease in ambulatory diastolic blood pressure (DBP) which did not reach statistical significance. Atenolol alone significantly reduced ambulatory systolic blood pressure (SBP) and DBP. Atenolol alone did not reduce VO2MAX. The combination of training and atenolol resulted in an increase in VO2MAX compared with atenolol alone, but no additional significant fall in blood pressure. Atenolol did not enhance the effect of physical training upon blood pressure and had little if any effect upon the training-induced increase in exercise tolerance.
The sequence method is widely used as a simple, non-invasive measure of baroreflex sensitivity (B... more The sequence method is widely used as a simple, non-invasive measure of baroreflex sensitivity (BRS). This technique, originally described in anaesthetized cats, has been transferred virtually unchanged to humans, without evidence that the optimal values in cats are the same as those in patients with cardiovascular disease. To study the effect of altering the components of the sequence method on the measured BRS in patients with chronic heart failure (CHF) and in normal individuals. Eighty patients with CHF [aged 62 +/- 12 years (mean +/- SD)] and 40 normal control individuals [aged 38 +/- 15 years (mean +/- SD)] underwent measurement of heart rate and non-invasive blood pressure. Altering only the shift between blood pressure and R-R interval and the required correlation coefficient of the regression line had no effect on the value of BRS, but had a significant effect on the number of valid sequences. Alteration of the blood pressure or R-R interval thresholds, however, affected not only the number of valid sequences, but also the value of BRS in both groups. In normal controls, agreement with the bolus phenylephrine method was improved by increasing the blood pressure threshold, although this led to a reduction in the number of valid sequences. In patients with CHF, agreement was optimized by decreasing both the blood pressure and R-R interval thresholds. This also had the effect of increasing the number of valid sequences. Changes should be made to this technique, to optimize its validity in conscious humans, particularly when applied to patients with attenuated BRS.
It is not known whether the temporal relationship between blood pressure (BP) and RR interval is ... more It is not known whether the temporal relationship between blood pressure (BP) and RR interval is modulated by the same mechanisms in normal controls and patients with chronic heart failure (CHF). We investigated this under conditions of controlled slow breathing. Fifty patients with CHF and 17 age-matched normals underwent recordings of BP and RR interval during 0.1 Hz controlled breathing. Fourier analysis was used to determine the phase relationships between the oscillations in respiration, BP and RR interval. There was no significant difference between patients and normals in the distribution of phase angle between respiration and BP (P=0.06) or between respiration and RR interval (P=0.21). There was, however, a significant difference in the phase relationship between BP and RR interval (P=0.03): in normals, BP led RR interval by a mean phase angle of 48.4 degrees (S.D. 16.8 degrees ). In patients with CHF, the distribution of phase difference was much wider [34.4 degrees (S.D. 62.8 degrees )]. The source of this wide distribution was patients with attenuated baroreflex sensitivity (BRS), with those with preserved BRS showing a relationship between BP and RR interval similar to the normal group. During controlled respiration, normal subjects exhibit a stereotyped relationship between oscillations in BP and RR interval, which is mediated by the baroreflex. This relationship is maintained in those patients with CHF who have a preserved BRS. In contrast, patients with an attenuated BRS show a wide distribution in the relationship between BP and RR interval ranging from completely in phase, to anti-phase. This may have important implications for the measurement and interpretation of BRS in patient groups where BRS is weak.
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