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Biomedical subjects

M Piepoli

Publications and source records attributed to M Piepoli.

At least 37 records · Page 2Linked to original sources
PubMed1998

Ventilatory response to exercise correlates with impaired heart rate variability in patients with chronic congestive heart failure.

In chronic congestive heart failure (CHF) an overactivity of muscle ergoreceptors and peripheral chemoreceptors may lead to an increased ventilatory response to exercise and contribute to the autonomic imbalance. The analysis of heart rate variability (HRV), which is a reliable method of studying autonomic regulations within the cardiovascular system, showed depressed HRV indexes in CHF, but predictors of abnormal HRV pattern in CHF remain controversial. Considering a common mechanism involved in generation of both abnormal ventilation and autonomic dysfunction in CHF, we hypothesized that impaired ventilation may be better than other variables of CHF severity in determining HRV parameters. Seventy-two patients with CHF (57+/-9 years, ejection fraction: 28+/-11%) underwent cardiopulmonary exercise testing; the relation between ventilation and carbon dioxide production (VE/VCO2) was used as an index of the ventilatory response to exercise. Time and frequency-domain measurements of HRV were derived from 24-hour electrocardiographic monitoring. Patients had reduced exercise tolerance with abnormal ventilatory response (peak oxygen consumption [VO2max]: 17.8+/-5.5 ml/kg/min, VE/VCO2: 36.0+/-9.8). Correlations were found between HRV measures and etiology, New York Heart Association (NYHA) functional class, and VO2max, but the strongest relation was observed for VE/VCO2 slope (r values from -0.33 to -0.65, p <0.01). In the multiple regression analysis only VE/VCO2 was found to correlate independently with all HRV measurements. To investigate the role of peripheral chemoreceptor overactivity as the mechanism of autonomic imbalance and the increased ventilatory response to exercise, we assessed peripheral chemosensitivity in 22 patients (mean value of peripheral chemosensitivity: 0.62+/-0.34 L/min/%SaO2, significantly higher than in normal controls, mean value: 0.29+/-0.20 L/min/%SaO2 in our laboratory). The activity of the peripheral chemoreflex inversely correlated with all parameters of HRV. Increased ventilatory response to exercise correlated with depressed HRV measures in patients with CHF better than other clinical variables. An important role of the increased peripheral chemosensitivity in this relation may be relevant, being also a potential link between functional severity and sympathovagal imbalance in CHF.

Administration, Inhalation↗
PubMed1998

Effects of Class III drugs on atrial fibrillation.

The Class III antiarrhythmic drugs have been used for the treatment of atrial fibrillation (AF); however, each has specific electrophysiologic properties that delineate different safety and/or effectiveness profiles. First-generation Class III agents seem to be more effective in preventing recurrence of AF than in converting AF to sinus rhythm. The high incidence of major cardiac and noncardiac side effects in the long term often requires discontinuation of the chronic antiarrhythmic therapy. The second-generation Class III drugs, ibutilide and dofetilide, have demonstrated interesting clinical applications, especially in the setting of atrial flutter. However, their favorable antiarrhythmic effect is counterbalanced by the high incidence of severe proarrhythmias. New promising experimental data suggest that the new Ikr-ks blockers may be free from these dangerous limitations, thus extending the indication of Class III drugs in the treatment of AF.

Animals↗
PubMed1997

Augmented peripheral chemosensitivity as a potential input to baroreflex impairment and autonomic imbalance in chronic heart failure.

BACKGROUND: The precise mechanisms responsible for the sympathetic overactivity and blunted baroreflex control in chronic heart failure (CHF) remain obscure. Augmented peripheral chemosensitivity has recently been demonstrated in CHF. We evaluated the relation between peripheral chemoreflex sensitivity and autonomic activity in patients with CHF. METHODS AND RESULTS: We studied in 26 stable patients with CHF the peripheral chemosensitivity (ventilatory response to hypoxia using transient inhalations of pure nitrogen), autonomic balance (spectral analysis of heart rate variability [HRV]), and baroreflex sensitivity (bolus phenylephrine method and alpha index). To determine whether transient inactivation of peripheral chemoreceptors might influence autonomic balance, 12 patients underwent a second study during which they breathed 100% O2. Peripheral chemosensitivity correlated inversely with HRV power within the low-frequency band (0.04 to 0.15 Hz) (r=-.52, P=.006) and inversely with baroreflex sensitivity (r=-.60, P=.005). When the patients were divided into two groups according to the chemosensitivity of age-matched normal controls (above and below mean+2 SDs of chemosensitivity of control subjects), those above the normal range revealed more impaired autonomic balance, ie, lower baroreflex sensitivity (1.4 +/- 1.3 versus 5.0 +/- 1.5 ms/mm Hg, P<.0001) and depressed values of low-frequency power (2.5 +/- 1.8 versus 4.1 +/- 0.8 ln ms2, P<.005) compared with those with normal chemosensitivity. Transient hyperoxia did not alter heart rate or systolic pressure but resulted in an increase in HRV and an improvement in baroreflex sensitivity. CONCLUSIONS: A link between increased peripheral chemosensitivity and impaired autonomic control, including baroreflex inhibition, is demonstrated. The clinical importance of this phenomenon warrants further investigation.

Aged↗
PubMed1997

Depressed heart rate variability as an independent predictor of death in chronic congestive heart failure secondary to ischemic or idiopathic dilated cardiomyopathy.

After acute myocardial infarction, depressed heart rate variability (HRV) has been proven to be a powerful independent predictor of a poor outcome. Although patients with chronic congestive heart failure (CHF) have also markedly impaired HRV, the prognostic value of HRV analysis in these patients remains unknown. The aim of this study was to investigate whether HRV parameters could predict survival in 102 consecutive patients with moderate to severe CHF (90 men, mean age 58 years, New York Heart Association [NYHA] class II to IV, CHF due to idiopathic dilated cardiomyopathy in 24 patients and ischemic heart disease in 78 patients, ejection fraction [EF], 26%; peak oxygen consumption, 16.9 ml/kg/min) after exclusion of patients in atrial fibrilation with diabetes or with chronic renal failure. In the prognostic analysis (Cox proportional-hazards model, Kaplan-Meier survival analysis), the following factors were investigated: age, CHF etiology, NYHA class, EF, peak oxygen consumption, presence of ventricular tachycardia on Holter monitoring, and HRV measures derived from 24-hour electrocardiography monitoring, calculated in the time (standard deviation of all normal RR intervals [SDNN], standard deviation of 5-minute RR intervals [SDANN], mean of all 5-minute standard deviations of RR intervals [SD], root-mean-square of difference of successive RR intervals [rMSSD], and percentage of adjacent RR intervals >50 ms different [pNN50]) and frequency domain (total power [TP], power within low-frequency band [LF], and power within high-frequency band [HF]). During follow-up of 584 +/- 405 days (365 days in all who survived), 19 patients (19%) died (mean time to death: 307 +/- 315 days, range 3 to 989). Cox's univariate analysis identified the following factors to be predictors of death: NYHA (p = 0.003), peak oxygen consumption (p = 0.01), EF (p = 0.02), ventricular tachycardia on Holter monitoring (p = 0.05), and among HRV measures: SDNN (p = 0.004), SDANN (p = 0.003), SD (p = 0.02), and LF (p = 0.003). In multivariate analysis, HRV parameters (SDNN, SDANN, LF) were found to predict survival independently of NYHA functional class, EF, peak oxygen consumption, and ventricular tachycardia on Holter monitoring. The Kaplan-Meier survival curves revealed SDNN < 100 ms to be a useful risk factor; 1-year survival in patients with SDNN < 100 ms was 78% when compared with 95% in those with SDNN > 100 ms (p = 0.008). The coexistence of SDNN < 100 ms and a peak oxygen consumption < 14 ml/kg/min allowed identification of a group of 18 patients with a particularly poor prognosis (1-year survival 63% vs 94% in the remaining patients, p <0.001). We conclude that depressed HRV on 24-hour ambulatory electrocardiography monitoring is an independent risk factor for a poor prognosis in patients with CHF. Whether analysis of HRV could be recommended in the risk stratification for better management of patients with CHF needs further investigation.

Aged↗
PubMed1997

Origin of respiratory sinus arrhythmia in conscious humans. An important role for arterial carotid baroreceptors.

BACKGROUND: We investigated whether respiratory sinus arrhythmia (RSA) in healthy humans originated from central neuronal oscillations or from peripheral baroreceptors responding to respiratory changes in venous return. METHODS AND RESULTS: During subjects' controlled breathing we used sinusoidal neck suction to influence RSA (spectral analysis of RR interval). In 11 subjects, 20-second apnea greatly reduced RSA, which was restored by neck suction at the frequency of respiration. Counteracting the respiration-induced cycles of carotid blood pressure decreased RSA in 13 subjects (from 2136 +/- 682 to 1372 +/- 561 ms2, P < .01). The critical phase of this neck suction was constant for each subject at around the phase shift (with regard to respiration-related fluctuations of blood pressure) best for smoothing respiratory (mechanical) changes in blood pressure. Suction of a non-baroreceptor area (the thigh) did not affect RSA. In 4 subjects, to separate the effects of peripheral baroreceptor afferents from respiration-entrained central oscillation (15 breaths/min), we cycled the neck suction at 12 cycles/min. Increasing neck suction from -7 to -30 mm Hg increased the ratio of the power of the 12 cycles compared with the 15-cycle RSA oscillation in RR interval spectral analysis from 0.26 to 2.57. A 12-cycle/min suction of an area other than the neck had little effect on the RR interval spectrum. CONCLUSIONS: RSA can be mimicked or reduced by stimulation of arterial baroreceptors with cycles of appropriately phased neck suction at the frequency of respiration. This suggests an important influence of the arterial baroreceptors in the generation of RSA in conscious humans.

Adult↗
PubMed1997

Clinical characteristics of chronic heart failure patients with an augmented peripheral chemoreflex.

AIMS: The peripheral chemoreflex may be augmented in chronic heart failure and may play a role in its pathophysiology including the mediation of exercise hyperpnoea and sympathetic activation. The objective of this study was to characterize the patients with an augmented peripheral chemoreflex. METHODS AND RESULTS: Peripheral chemoreflex sensitivity was assessed by measuring the ventilatory response to hypoxia using transient inhalations of pure nitrogen in 50 patients with chronic heart failure (age 58.7 +/- 12.1 (SD) years; radionuclide left ventricular ejection fraction 26.5 +/- 13.0%). The peripheral chemoreflex of 12 healthy controls with similar demographic characteristics was 0.272 +/- 0.201l.min-1.%Sao(2)-1 compared with 0.673 +/- 0.410l. min-1.%Sao(2)-1 (P < 0.0001) in the chronic heart failure patients. Using 2 standard deviations above the mean level of the controls peripheral chemoreflex sensitivity as the upper limit of normal, we defined an augmented chemoreflex as greater than 0.6751.min-1.%Sao(2)-1. Twenty of the chronic heart failure patients (40%) demonstrated such an augmented peripheral chemoreflex. Compared with patients with peripheral chemoreflex sensitivity within the normal range, they had a reduced peak oxygen consumption during cardiopulmonary exercise (15.1 +/- 4.4 vs 18.5 +/- 5.8 ml.kg-1.min-1, P = 0.02), reduced radionuclide left ventricular ejection fraction (21.8 +/- 11.8 vs 29.4 +/- 13.1%, P = 0.046) and were in a worse New York Heart Association functional class (2.8 vs 2.4, P = 0.05). The ventilatory response to exercise, as characterized by the regression slope relating minute ventilation to carbon dioxide output during exercise, was also higher (40.48 +/- 9.32 vs 34.54 +/- 7.19, P = 0.02), consistent with the role of the peripheral chemoreflex in mediating exercise hyperpnoea. There was also an increased proportion of patients with non-sustained ventricular tachycardia in the group with an augmented peripheral chemoreflex (61% vs 21%, chi-squared 7.08, P < 0.01). No difference was seen in the age, height, weight and lung function measurements of these patients compared with the normal chemoreflex group. CONCLUSION: An augmented peripheral chemoreflex is a common finding in chronic heart failure patients, one associated with increasing severity and with the exercise hyperpnoea seen in the condition. That there was an excess of patients with non-sustained ventricular tachycardia in the group with an augmented peripheral chemoreflex may be related to the chemoreflex-driven sympathetic stimulation. The peripheral chemoreflex may be important in the pathophysiology of chronic heart failure, both in terms of symptoms and exercise limitation.

Case-Control Studies↗
PubMed1997

Chemoreceptor dependence of very low frequency rhythms in advanced chronic heart failure.

Factors responsible for very low frequency oscillations (VLF; cycle > 30 s) in the cardiovascular system remain obscure. We tested the hypothesis that increased peripheral chemosensitivity is important in the pathogenesis of VLF oscillations in patients with chronic heart failure (CHF). Fourteen male patients with stable, moderate to severe CHF (age 60 +/- 1.1 yr, ejection fraction 23 +/- 11%) and reproducible VLF oscillations in heart rate underwent a protocol consisting of three consecutive 20-min phases during which they breathed air, hyperoxia (O2 via mask, 60% O2 concn), and air again. Autoregressive spectral analysis of R-R intervals, blood pressure, and respiration was used to quantify total oscillatory power (TP), VLF, low (0.04-0.15 Hz)- and high (0.15-0.40Hz)-frequency power, and the coherence between these signals. Peripheral chemosensitivity was studied by assessing the ventilatory response to hypoxia using transient inhalations of pure N2. Discrete VLF rhythms were seen in R-R intervals in all 14 patients, in blood pressure in 7 of 14, and in respiration in 8 of 14 patients. A significant coherence (> 0.5) between heart rate and systolic blood pressure within the VLF band with mean phase value of -140 degrees, suggesting an antibaroreflex relationship, was seen in six subjects. Transient hyperoxia abolished the VLF oscillations in most subjects (12 of 14 in R-R intervals) and decreased R-R variability power within the VLF band. This response significantly correlated with peripheral chemoreceptor sensitivity (r = 0.77, P = 0.014). This study suggests that in CHF, enhanced peripheral chemoreceptor activity may facilitate slow oscillations in the cardiorespiratory signals.

Aged↗
PubMed1996

P-wave dispersion index: a marker of patients with paroxysmal atrial fibrillation.

The P-wave triggered signal-averaged ECG (PSA-ECG) has shown controversial results in the evaluation of patients with paroxysmal atrial fibrillation (PAF). Previously tested PSA-ECG parameters, i.e. P-wave filtered duration (Pd), root mean square voltage of the last 20 ms of the P-wave vector magnitude (RMS20) were compared with an index of P-wave dispersion (PDi = Pd (X, Y, Z lead) S.D./mean value x 100) in the evaluation of 40 subjects (24 M, 54 +/- 7 years) with or without PAF, without anti-arrhythmic therapy. Patients presented vs. controls higher Pd values (138 +/- 14 ms vs. 120 +/- 12 ms, P < 0.0005), PDi (8 +/- 2 ms vs. 1 +/- 1 ms, P < 0.0001) but no difference in RMS20. In the comparison of patients vs. controls, Pd > or = 125 ms presented 62% sensitivity and 78% specificity, PDi > or = 5.5 ms showed 83% sensitivity and 81% specificity: the combination of these two criteria differentiated a subgroup of patients with no recurrence of PAF in a 12 +/- 4 months follow-up PDi and Pd could be powerful criteria in the identification of patients and could be able to identify patients with low recurrences of PAF.

Atrial Fibrillation↗
PubMed1996

Detection and significance of a discrete very low frequency rhythm in RR interval variability in chronic congestive heart failure.

Although in advanced chronic congestive heart failure (CHF) very low frequency (< 0.04 Hz, VLF) oscillations are prominent, the clinical importance and the physiologic basis of these rhythms have not been elucidated. To investigate the physiologic determinants of the VLF rhythms in RR interval variability, we studied 36 patients with stable, moderate to severe CHF (33 men, age: 58 +/- 8 years, ejection fraction 25 +/- 10%, peak oxygen consumption 18.1 +/- 4.6 ml/kg/min) and 12 age- and sex-matched controls using autoregressive spectral analysis of RR interval, blood pressure, and respiratory signals during controlled conditions. We quantified low frequency (LF) (0.04 to 0.15 Hz), high frequency (HF) (0.15 to 0.40 Hz), VLF, and total power (0 to 0.5 Hz), and calculated the coherence between systolic blood pressure and RR interval variability within each band. Peripheral chemosensitivity was assessed by the ventilatory response to hypoxia using transient inhalation of pure nitrogen. The influence of transient inactivation of peripheral chemoreceptors on the VLF rhythm was investigated by exposing 6 patients to hyperoxic (60% oxygen) conditions for 20 minutes. Twenty-three patients (64%) with CHF, but no controls, had a discrete VLF rhythm (0.019 +/- 0.008 Hz) in RR variability. The presence of VLF rhythm was not related to any difference in clinical parameters (etiology, New York Heart Association class, ejection fraction, oxygen uptake) but rather to a different pattern in RR interval and blood pressure variability: lower LF power (2.8 +/- 1.6 ms2 natural logarithm [ln]) compared either to patients without VLF (4.0 +/- 1.3 ms2 ln) or to controls (5.9 +/- 0.7 ms2 ln), higher percentage of power within VLF band (86.3 +/- 8.3% vs 77.5 +/- 7.9% and 61.5 +/- 14.1%) and a markedly impaired coherence between RR interval and systolic blood pressure variability within the LF band (0.26 +/- 0.10 vs 0.42 +/- 0.18 and 0.63 +/- 0.15, in patients with vs without VLF peak and controls, respectively). Patients with VLF had significantly increased hypoxic chemosensitivity, and hyperoxic conditions were able to decrease VLF power and abolish the VLF rhythm in 5 of 6 patients with CHF. Discrete VLF oscillations in RR variability are common in patients with advanced CHF and appear to be related to severely impaired autonomic regulation and suppression of baroreceptor function, with enhancement of hypoxic chemosensitivity. We hypothesize that this rhythm represents an enhanced chemoreflex harmonic oscillation in CHF patients, which may have application for arrhythmogenesis.

Autonomic Nervous System↗
PubMed1996

Contribution of muscle afferents to the hemodynamic, autonomic, and ventilatory responses to exercise in patients with chronic heart failure: effects of physical training.

BACKGROUND: A neural linkage between peripheral abnormalities and the exaggerated exercise responses in chronic heart failure (CHF) was postulated. We studied the ergoreceptors (afferents sensitive to skeletal muscle work) in CHF and whether training can affect their activity. METHODS AND RESULTS: In 12 stable CHF patients (ejection fraction [EF] = 26.4%) and 10 control subjects (EF = 55.3%), we compared the responses to dynamic handgrip and during a 3-minute period of posthandgrip regional circulatory occlusion (PH-RCO). The ergoreflex contribution was quantified as the percentage responses to exercise maintained by PH-RCO compared with recovery without PH-RCO. Patients showed ergoreflex overactivation compared with control subjects in terms of ventilation (86.5% versus 54.5%), diastolic pressure (97.8% versus 53.5%), and leg vascular resistance (108.1% versus 48.9%) (all P < .05). The contribution of the ergoreflex to vagal withdrawal (high frequency of RR variability) and sympathetic activation (low frequency of RR, pressure variability) was evident in both groups. Nine control subjects and nine CHF patients participated in 6 weeks of forearm training. Training reduced the ergoreflex contributions more in CHF than in control subjects: diastolic pressure (-33.2% versus -4.6%), ventilation (-57.6% versus -24.6%), and leg vascular resistance (-59.9% versus -8.0%) (all P < .05). CONCLUSIONS: (1) The ergoreflex role has a larger effect on the responses to exercise in CHF than in control subjects. (2) Training may reduce this exaggerated ergoreflex activity, thereby improving the responses to exercise.

Exercise Tolerance↗
PubMed1996

Factors which alter the relationship between ventilation and carbon dioxide production during exercise in normal subjects.

The slope of the linear relationship between ventilation (V(E)) and carbon dioxide production (VC0(2)) has been thought to indicate that VC0(2) is one of the major stimuli to V(E). A group of 15 normal subjects undertook different incremental treadmill exercise protocols to explore the relationship between V(E) and VCO(2). An incremental protocol using 1 instead of 3-min stages of exercise resulted in an increase in the V E to VCO(2) ratio [26.84 (SEM 1.23) vs 31.08 (SEM 1.36) (P <0.008) for the first stage, 25.24 (SEM 0.86) vs 27.83 (SEM 0.91) (P <0.005) for the second stage and 23.90 (SEM 0.86) vs 26.34 (SEM 0.81) (P = 0.001) for the third stage]. Voluntary hyperventilation to double the control level of V(E) during exercise resulted in an increase in the V(E) to VCO(2) slope [from 21.3 (SEM 0.71) for the control run to 35.1 (SEM 1.2) for the hyperventilation run (P <0.001)]. Prolonged hyperventilation (5 min) during exercise at stage 2 of the Bruce protocol resulted in a continued elevation of VCO(2) and the V(E)/VCO(2) slope. A steady state of V(E) and metabolic gas exchange can only be said to have been present after at least 3 min of exercise. Voluntary hyperventilation increased the slope of the relationship between V(E) and VCO(2). End-tidal carbon dioxide fell, but remained within the normal range. These results would suggest that a non-carbon dioxide factor may have been responsible for the increase we found in V(E) during exercise, and that factors other than increased dead space ventilation can cause an increased ventilation to VCO(2) slope, such as that seen in some pathophysiological conditions, such as chronic heart failure.

Adult↗
PubMed1996

Heart rhythms, ventricular arrhythmias, and death in chronic heart failure.

BACKGROUND: The aim of this study was to evaluate whether abnormalities in heart rate variability (HRV) could act as markers of ventricular tachycardia and prognosis in patients with advanced, chronic heart failure. Fifty patients with chronic heart failure (45 men; mean age, 59 +/- 9 years; New York Heart Association [NYHA] class II-III; left ventricular ejection fraction [LVEF], 19 +/- 9% and peak oxygen consumption, 16.6 +/- 5.4 mL/kg/min) caused by idiopathic dilated cardiomyopathy (n = 12) and ischemic heart disease (n = 38) were included in the study. Heart rate variability measures derived from 24-hour electrocardiographic (ECG) monitoring (Marquette 8500 recorder, Marquette Electronics, Milwaukee, WI) were calculated in the time domain and frequency domain. METHODS AND RESULTS: Twenty-five patients (50%) revealed episodes of ventricular tachycardia on 24-hour ECG monitoring (1-143 episodes). The presence of ventricular tachycardia was associated with lower LVEF but there was no difference in NYHA class and peak oxygen consumption between patients with and without ventricular tachycardia (LVEF, 16 vs 22%, P = .01; NYHA class, 2.6 vs 2.4; peak oxygen consumption, 16.5 vs 16.8 mL/kg/min, not significant). Patients with ventricular tachycardia exhibited markedly lower HRV measures. Multiple regression analysis was used to test HRV parameters as potential predictors of ventricular tachycardia. Among them, high-frequency power was the only independent predictor of the presence of ventricular tachycardia, and this predictive correlation was independent of LVEF and mean R-R interval duration. During a follow-up period of 24 +/- 18 months, 12 patients (24%) died. No difference was found in age, etiology, NYHA class, peak oxygen consumption, or occurrence of ventricular tachycardia, but a lower LVEF (15 +/- 6 vs 21 +/- 9%, P = .046) was observed in those who died compared with those who survived. Certain estimates of HRV were in contrast, lower in those who subsequently died: standard deviation of all normal R-R intervals (61 +/- 30 vs 101 +/- 33 ms), standard deviation of 5-minute mean R-R intervals (55 +/- 27 vs 92 +/- 31 ms), mean of all 5-minute standard deviations of R-R intervals (22 +/- 12 vs 37 +/- 11 ms), and the low-frequency (3.2 +/- 1.8 vs 4.8 +/- 0.9 ln ms2) and high-frequency (3.0 +/- 1.1 vs 3.8 +/- 0.8 ln ms2) components of the HRV spectrum (all differences, P < .01). In univariate Cox analysis, all of these HRV measures were independent predictors of death. Kaplan-Meier survival analysis revealed that the standard deviations of all normal R-R intervals and of 5-minute mean R-R intervals dichotomized at median values (99 and 90.5 ms, respectively) were the best predictors of mortality. CONCLUSIONS: In patients with moderate to severe chronic heart failure, depressed indices of HRV on 24-hour ambulatory ECG monitoring could be related to higher risk of ventricular tachycardia and death, suggesting that analysis of HRV could be usefully applied to risk stratification in chronic heart failure patients.

Arrhythmias, Cardiac↗
PubMed1996

Physical training enhances sympathetic and parasympathetic control of heart rate and peripheral vessels in chronic heart failure.

1. Physical training has been proposed to increase vagal control of heart rate in chronic heart failure. We studied the effects of physical training on cardiovascular control in 6 moderate to severe heart failure (NYHA II-III) patients and 6 age matched normal controls in a randomized controlled cross over trial (Training vs Detraining). 2. Five weeks training (20 min/day, 5 days/week bicycle exercise) increased peak VO2 in both C (from 31.2 +/- 1.4 to 37.7 +/- 2.4 ml/kg/min p < 0.01) and CHF patients (from 12.16 +/- 2.2 to 14.13 +/- 2 ml/kg/min p < 0.05). The sympathovagal control of heart rate and sympathetic control of the resistance vessels was assessed by the power of the oscillations (LF:0.03-0.15 Hz index of sympathetic activity, HF: 0.18-0.35 Hz index of vagal activity) in RR interval, blood pressure (systolic and diastolic by Finapres) and respiration by autoregressive spectral analysis, during free and controlled breathing (15b/min), in order to increase vagal activity. 3. T increased heart rate vagal control both in C (LF/HF ratio fb to cb: (D) 1.73 +/- 0.35 to 1.19 +/- 0.43 p = NS: (T) 2.9 +/- 1.2 to 1.13 +/- 0.3 p < 0.05) and in CHF patients (LF/HF ratio fb to cb: (D) 2.05 +/- 0.56 to 1.24 +/- 0.21 p = NS; (T) 2.6 +/- 0.89 to 0.87 +/- 0.15 p < 0.05; and in cb HF%: 36.2 +/- 2.7 (D) to 46.2 +/- 4.8 (T) p < 0.05). Before T, the sympathetic modulation of peripheral vessels (% LF compared to total variability) was depressed in CHF vs C (SBP: 9 +/- 2 vs 42 +/- 12% p < 0.05; DBP: 29 +/- 7 vs 55 +/- 31%, p < 0.05), and increased significantly after T in CHF (SBP from 9 +/- 2 (D) to 19 +/- 5% (T) p < 0.05; DBP from 29 +/- 7 to 41 +/- 11% (T) p < 0.05). This suggests an overall increase of autonomic control, both vagal on the heart and sympathetic on the peripheral vessels, in CHF by physical training.

Autonomic Nervous System↗