Effects of aerobic training in patients with moderate chronic heart failure]

To evaluate the effects of a program of moderate intensity in patients (pts) with clinically stable chronic heart failure (CHF), we studied 20 pts (18M, 2F, mean age 61 years) with dilated cardiomyopathy, Weber Class B, ejection fraction (EF) < 40% and aerobic capacity of 16 +/- 2 ml/kg/min on cardiopulmonary exercise testing. We randomly assigned pts to 2 groups, a training group (T, 10 pts) and a control group (C, 10 pts), similar for anatomical and clinical characteristics, group T underwent a thrice weekly, 8 week-long ambulatory program of aerobic activity, beginning at 40% of maximal oxygen uptake. At the end, in Group T we observed a significant increase of exercise tolerance (+45%; p < 0.005), peak oxygen uptake (VO2 max) (+20%; p < 0.001), anaerobic ventilatory threshold (AT) (+37%; p < 0.005), lactate threshold (+36%; p < 0.005), peak heart rate (< 10%; p < 0.01) and of peak systolic pressure (+12%; p < 0.007); and a significant reduction in resting heart rate (-17%; p < 0.005), resting diastolic pressure (-11%; p < 0.005), plasma lactate (LA) at rest (-26%; p < 0.01), at peak (-21%; p < 0.005) and at recovery (-22%; p < 0.005), plasma norepinephrine (NE) both at rest (-38%; p < 0.005) and at peak (-13%; p < 0.005) and of plasma epinephrine (E) (-38%; p < 0.005; -32%, p < 0.001, respectively). We observed no change in EF at the end in both groups nor any untoward cardiac effects during training. We didn't note any correlation between AT and venous oxygen saturation (r = 0.15; p = 0.65) changes at the end. The increase in peak VO2 after training was not correlated to any AT increase (r = 0.12; p = 0.72). We observed, however, a significant correlation between lactate threshold and AT changes after training (r = 0.81; p = 0.005) and between LA and resting, submaximal and peak NE (r = 0.89; p = 0.005) and E (r = 0.78; p = 0.007) changes at the end of training. CONCLUSIONS: a) in pts with clinically stable CHF a program of aerobic activity well tolerated in terms of frequency, intensity and duration may determine a significant increase in exercise tolerance, aerobic capacity, AT and LA threshold, and a significant decrease in plasma LA, NE and E at rest, submaximal and peak levels; b) in our opinion, such modifications are partly determined by a delay in lactate accumulation and partly by sympathetic tone lowering, and permit us to underline the concept that physical inactivity may provoke important peripheral changes that, in turn, may reduce exercise tolerance and aerobic capacity, by creating a vicious circle difficult to break by medical therapy alone.     

Six-month aerobic exercise training ameliorates central sleep apnea in patients with chronic heart failure

BackgroundSleep-disordered breathing (SDB) is common in patients with heart failure and carries an independent risk for poor long-term prognosis. We aimed to study the effects of supervised, aerobic exercise training for 6 months on SDB in patients with chronic heart failure.Methods and ResultsWe enrolled 18 patients having both systolic dysfunction (left ventricular ejection fraction <45%) and SDB (apnea-hypopnea index [AHI] >10). The exercise group comprised 10 patients who participated in our cardiac rehabilitation program for 6 months, and the remaining 8 patients served as control. AHI (median [interquartile range]) was unchanged in the control group patients at 6-month intervals (30.4 [19.9–36.3] versus 36.6 [8.6–39.4], NS). In contrast, AHI was significantly decreased in the exercise group from 24.9 [19.2–37.1] to 8.8 [5.3–10.1] (P < .01). In the exercise group, the numbers of central sleep apnea per night was significantly decreased (152 [124–244] versus 50 [24–67], P < .01) after exercise training, but those of obstructive apnea/hypopnea were unchanged (42 [7–94] versus 18 [7–54], NS). In addition, exercise training significantly increased peak oxygen consumption and decreased minute ventilation to carbon dioxide production slope (both P < .01).ConclusionsSix-month, aerobic exercise training increased exercise capacity and improved central sleep apnea in patients with chronic heart failure from systolic dysfunction.     

Effects of group-based high-intensity aerobic interval training in patients with chronic heart failure

The aim of this study was to evaluate the effectiveness of a novel group-based aerobic interval training of high intensity on functional capacity and quality of life in patients with chronic heart failure (CHF) and examine the relation between changes in functional capacity and quality of life. Eighty patients with stable CHF (63 men, 17 women; mean age 70.1 +/- 7.9 [SD] years; left ventricular ejection fraction 30 +/- 8.5%) on optimal medical treatment were randomly assigned to either a 16-week group-based aerobic high-intensity interval training model twice weekly for 65 to 80 minutes/day (n = 40) or a control group (n = 40) that received standard care. Functional capacity was measured using the 6-minute walk test and cycle ergometer test. Quality of life was measured using the Minnesota Living with Heart Failure Questionnaire. After 16 weeks, functional capacity improved significantly in the exercise group compared with the control group measured using the 6-minute walk test (+58 vs -15 meters; p <0.001) and for both workload and time measured using the bicycle ergometer test (+10 vs -1 W; p < 0.001; + 57 vs -8 seconds; p <0.001). Quality of life improved significantly in the exercise group compared with the control group (p = 0.03), and a significant inverse correlation was found between quality of life and functional capacity (r = -0.49, p <0.05). In conclusion, our exercise model significantly improved functional capacity and quality of life compared with the control group in patients with CHF. Improvements in quality of life were significantly related to functional capacity.     

Comparison of low-frequency electrical myostimulation and conventional aerobic exercise training in patients with chronic heart failure.

BACKGROUND: Physical training is recommended as an efficient therapy in patients with chronic heart failure (CHF). Low-frequency electrical myostimulation (EMS) has recently been suggested as a good alternative to conventional aerobic training. The aim of this study was to compare the effects of EMS and conventional exercise training in patients with moderate to severe CHF. METHODS: Twenty-four patients with stable CHF (56.7+/-7.3 years, New York Heart Association grades II and III) underwent 5 weeks of exercise training, 5 h a week, using EMS (n=12) or conventional (n=12) training programmes. At baseline and after the training period, patients performed a symptom-limited cardiopulmonary test, a 6-min and a 200-m walk exercises and an evaluation of maximal knee extensor strength. RESULTS: Oxygen uptake (VO2) and workload at the end of exercise (peak values) and at ventilatory threshold increased after EMS (P< or =0.05) and conventional exercise (P<0.05) training programmes. The slope of the relationship between VO2 and workload was reduced after EMS (P<0.05). The time to recover half of peak VO2 decreased irrespective of the training programme (P<0.001). EMS and conventional exercise training programmes also increased the maximal knee extensor strength (P<0.05), the distance walked in 6 min (P<0.01) and decreased the time elapsed to cover 200 m (P<0.05). These improvements were not statistically different between EMS and conventional exercise. CONCLUSION: In patients with moderate to severe CHF, 5 weeks of EMS and conventional exercise training produce similar improvements to exercise capacity and muscle performance.     

Effects of exercise training on abnormal ventilatory responses to exercise in patients with chronic heart failure

Patients with chronic heart failure frequently report shortness of breath during daily activities as their primary symptom. In recent years, many efforts have been made by researchers to explain the mechanisms that underlie the characteristic heightened ventilatory response to activity in patients with chronic heart failure. The degree to which the ventilatory response to exercise is heightened parallels the severity of the disease, and measuring the ventilatory gas exchange response to exercise can help quantify the patient's response to therapy. Prior to the 1990s, patients with chronic heart failure were generally discouraged from participating in programs of exercise training. However, in the last decade, studies have demonstrated that exercise training is quite safe for these patients, and a multitude of benefits have been reported. Among the benefits of training are improvements in the abnormal ventilatory response to exercise. Although many mechanisms could potentially explain this response, it appears most likely that this improvement after training is due to a reduction in lactate accumulation and an attenuation of the heightened muscle receptor reflex response that occurs in chronic heart failure. This article reviews the mechanisms of dyspnea in chronic heart failure, along with recent studies assessing the effects of training on abnormal ventilatory responses to exercise in these patients. (c)2000 by CHF, Inc.     

Effects of exercise training on endothelial progenitor cells in patients with chronic heart failure

BackgroundThe enhancement of circulating endothelial progenitor cells (EPCs) obtained by exercise training can be beneficial to patients with cardiac disease. Changes in the levels and differentiation of CD34^pos/KDR^pos EPCs, as well as the plasma concentration of vascular endothelial growth factor (VEGF) and stromal cell-derived factor (SDF)-1 EPC-mobilizing cytokines, were evaluated in patients with chronic heart failure after 8 weeks of supervised aerobic training (SAT) and 8 weeks of subsequent discontinued SAT (DSAT).Methods and ResultsThe levels of circulating EPC and EPC differentiation potential of 22 patients who underwent SAT were studied by fluorescence-activated cell sorter analysis and colony forming-unit assay, respectively. The plasma levels of VEGF and SDF-1 were measured by enzyme-linked immunosorbent assay. In response to SAT, the levels of both EPC and VEGF/SDF-1 markedly increased (P < .001 vs baseline) but returned to the baseline levels after DSAT. A similar change was observed with the EPC clonogenic potential, but on DSAT the baseline level was incompletely attained.ConclusionsIn response to SAT, patients with chronic heart failure show enhanced EPC levels and clonogenic potential that is mirrored by increased plasma VEGF and SDF-1 levels. DSAT can interfere with the maintenance of training-acquired VEGF/SDF-1-related EPC levels and clonogenic potential.     

The effects of exercise training on patients with chronic heart failure

The activity levels of patients with chronic heart failure are limited by breathlessness and muscle fatigue. An overview of the factors contributing to this reduction in exercise tolerance is presented. The review of the studies indicates these changes can be reversed by a period of exercise training with a concomitant improvement in quality of life. Problems in comparing different training programmes and the use of different outcome measures are discussed. Recommendations for exercise programmes are made based on the findings of this review.     

Effects of exercise training on diastolic and systolic dysfunction in patients with chronic heart failure

BACKGROUNDChronic heart failure (CHF) is a complex syndrome characterized by a progressive reduction of the left ventricular (LV) contractility, low exercise tolerance, and increased mortality and morbidity. Diastolic dysfunction (DD) of the LV, is a keystone in the pathophysiology of CHF and plays a major role in the progression of most cardiac diseases. Also, it is well estimated that exercise training induces several beneficial effects on patients with CHF. AIMTo evaluate the impact of a cardiac rehabilitation program on the DD and LV ejection fraction (EF) in patients with CHF.METHODSThirty-two stable patients with CHF (age: 56 ± 10 years, EF: 32% ± 8%, 88% men) participated in an exercise rehabilitation program. They were randomly assigned to aerobic exercise (AER) or combined aerobic and strength training (COM), based on age and peak oxygen uptake, as stratified randomization criteria. Before and after the program, they underwent a symptom-limited maximal cardiopulmonary exercise testing (CPET) and serial echocardiography evaluation to evaluate peak oxygen uptake (VO_2peak), peak workload (W_peak), DD grade, right ventricular systolic pressure (RVSP), and EF.RESULTSThe whole cohort improved VO_2peak, and W_peak, as well as DD grade (P < 0.05). Overall, 9 patients (28.1%) improved DD grade, while 23 (71.9%) remained at the same DD grade; this was a significant difference, considering DD grade at baseline (P < 0.05). In addition, the whole cohort improved RVSP and EF (P < 0.05). Not any between-group differences were observed in the variables assessed (P > 0.05).CONCLUSIONExercise rehabilitation improves indices of diastolic and systolic dysfunction. Exercise protocol was not observed to affect outcomes. These results need to be further investigated in larger samples.     

A comparison of ambulatory oxygen consumption during circuit training and aerobic exercise in patients with chronic heart failure.

PURPOSE: This study compared the exercise intensity of a combined aerobic and resistance exercise circuit training session with the exercise intensity of continuous aerobic exercise in patients with chronic heart failure (CHF). METHODS: Peak oxygen consumption (VO2peak) and muscular strength (1 repetition maximum) were assessed in six CHF patients (age 62 +/- 3 years). Heart rate, rate of perceived exertion (RPE), blood pressures, ambulatory oxygen consumption (VO2), and ventilatory data were measured during two types of exercise: continuous cycling on a bicycle ergometer (aerobic [AER] session) and combined AER and resistance exercise (circuit training [CIR] session). RESULTS: There were no significant differences in VO2, RPE, heart rate, or hemodynamic responses (rate pressure product, diastolic blood pressure, or mean arterial pressure) during exercise, between the two sessions. Systolic blood pressure was significantly lower during CIR (P < 0.05). Minute ventilation and tidal volume were significantly higher (P < 0.0001 and P < 0.01, respectively) and respiratory frequency significantly lower (P < 0.005) during CIR. During CIR, RPE significantly correlated with VO2 (P < 0.01), whereas heart rate did not. Conversely, during the AER session HR correlated with VO2 (P < 0.01), but RPE did not. CONCLUSIONS: Circuit training is a well-tolerated form of exercise training for CHF patients that is associated with similar oxygen and hemodynamic demand to aerobic exercise. Results suggest that RPE may be a better method of prescribing and monitoring exercise intensity during CIR, with heart rate the preferred measure of intensity during aerobic exercise.     

Effects of cardiac resynchronization therapy on ventricular repolarization in patients with congestive heart failure

INTRODUCTION: Biventricular pacing has been shown to improve the clinical status of patients with congestive heart failure, but little is known about its influence on ventricular repolarization. The aim of our study was to evaluate the effect of biventricular pacing on ECG markers of ventricular repolarization in patients with congestive heart failure. METHODS AND RESULTS: Twenty-five patients with congestive heart failure, sinus rhythm (SR), and complete LBBB (6 females; age 61 +/- 8 years; NYHA class II-III; echocardiographic ejection fraction 21 +/- 5%; QRS > or = 130 ms) underwent permanent biventricular DDDR pacemaker implantation. A high-resolution 65-lead body-surface ECG recording was performed at baseline and during right-, left-, and biventricular pacing, and the total 65-lead root mean square curve of the QRST complex and the interlead QT dispersion were assessed. The QRS duration was increased during right (RV)- and left ventricular (LV) pacing (127 +/- 26% and 117 +/- 40%; P < 0.05), as compared to SR (100%) and biventricular pacing (93 +/- 16%; ns). The QTc interval was increased during RV and LV pacing (112 +/- 12% and 114 +/- 14%; P < 0.05) as compared to SR (100%) or biventricular pacing (99 +/- 12%). There was no effect on JT interval during all pacing modes. The T(peak-end) interval was increased during right (120 +/- 34%; P < 0.01) and LV pacing (113 +/- 29%; P < 0.05) but decreased during biventricular pacing (81 +/- 19%; P < 0.01). A similar effect was found for the T(peak-end) integral and the T(peak) amplitude. QT dispersion was increased during right ventricular (129 +/- 16 ms; P < 0.05) and decreased during biventricular pacing (90 +/- 12 ms; P < 0.01), as compared to SR (114 +/- 22 ms). CONCLUSIONS: Using a high-resolution surface ECG, biventricular pacing resulted in a significant reduction of ECG markers of ventricular dispersion of repolarization.     

Central adaptations to exercise training in patients with chronic heart failure

In chronic heart failure patients, the increase of peak VO₂ observed after a period of aerobic training is currently attributed more to peripheral (skeletal muscle) than central (heart) adaptations. This paper reviews the current scientific evidence regarding the existence or the absence of significant training-induced adaptations of peak cardiac output and its determinants in patients with chronic heart failure due to left ventricular systolic dysfunction. It is concluded that, on the basis of available literature, a training-induced significant increase of peak cardiac output with respect to pre-training values does exist in the chronic heart failure population. Such an effect is due to adaptations of the main cardiac output determinants, that is, heart rate and stroke volume, whose relative contribution to the cardiac output increase will vary in the single patient due to variability in the individual response to the training stimulus. Moreover, these data emphasize both the safety and even the central morpho-functional benefits of aerobic training programs in the chronic heart failure population, setting the stage for an even more widespread use of this non-pharmacologic intervention in the everyday clinical practice. As most studies considered in this review were conducted in the pre-beta-blockers era, the possibility to extend the conclusions of this paper to chronic heart failure patients on beta-blocking therapy remains to be verified.     

Effects of exercise training on inflammatory markers in patients with heart failure

Cardiologists now recognize that the cardio-centric model of heart failure does not sufficiently explain the entire traits particular to chronic heart failure. Evidence accumulates, that many features of the syndrome can be explained by the known biological effects of inflammatory mediators. Indeed, when expressed in experimental models at concentrations commonly observed in heart failure, inflammatory mediators such as tumor necrosis factor-α, interleukin-6, and nitric oxide can produce effects that mimic features of heart failure, including (but not limited to) progressive left-ventricular dysfunction, pulmonary edema, left-ventricular remodeling, and cardiomyopathy. As we witness anti-cytokine therapies and other strategies to avoid an increase in cytokines we have been shown that acute bouts of exercise are associated with an increase in pro-inflammatory cytokines and markers of oxidative stress. As a consequence we have been warned exercise may thus even further contribute to the deterioration of heart failure. However, there are several randomized trials which unanimously document that chronic—as opposed to acute bouts of—exercise does not only lead to a reduction of cytokines and oxidative stress, but that patients dramatically benefit by the increase in maximal oxygen consumption, exercise capacity, quality of life, reduction in hospitalization, morbidity, and mortality. Over the past two decades it has become evident that cytokine research has come to stay and that we will continue to see anti-cytokine treatment strategies for our patients. It is the aim of this review to shed some more light on the most commonly investigated and most relevant cytokines.