Exercise testing and training of patients with heart failure due to left ventricular systolic dysfunction

Intense tai chi exercise training and fall occurrences in older, transitionally frail adults: a randomized, controlled trial

OBJECTIVES

To determine whether an intense tai chi (TC) exercise program could reduce the risk of falls more than a wellness education (WE) program in older adults meeting criteria for transitioning to frailty.

DESIGN

Randomized, controlled trial of 48 weeks duration.

SETTING

Twenty congregate living facilities in the greater Atlanta area.

PARTICIPANTS

Sample of 291 women and 20 men aged 70 to 97.

MEASUREMENTS

Demographics, time to first fall and all subsequent falls, functional measures, Sickness Impact Profile, Centers for Epidemiologic Studies-Depression Scale, Activities-specific Balance Confidence Scale, Falls Efficacy Scales, and adherence to interventions.

RESULTS

The risk ratio (RR) of falling was not statistically different in the TC group and the WE group (RR=0.75, 95% confidence interval (CI)=0.52-1.08), P=.13). Over the 48 weeks of intervention, 46% (n=132) of the participants did not fall; the percentage of participants that fell at least once was 47.6% for the TC group and 60.3% for the WE group.

CONCLUSION

TC did not reduce the RR of falling in transitionally frail, older adults, but the direction of effect observed in this study, together with positive findings seen previously in more-robust older adults, suggests that TC may be clinically important and should be evaluated further in this high-risk population.

Exercise training for heart failure patients improves respiratory muscle endurance, exercise tolerance, breathlessness, and quality of life

PURPOSE

Increased respiratory muscle endurance and peak oxygen consumption (VO(2peak)) induced by respiratory muscle training support the relationship between respiratory muscle function and exercise capacity in patients with heart failure. This raises the question whether exercise-training results in increased respiratory muscle function contributing to an increased exercise tolerance, a decreased perception of breathlessness, and an improved quality of life.

METHODS

Prospective cohort analysis was completed on 24 patients with New York Heart Association (NYHA) Class III heart failure [18 men, 6 women; aged = 64 (SD 7.9) years; percent ejection fraction (%EF) = 24.0 (SD 7.8)]. Maximal sustainable ventilatory capacity (MSVC), submaximal and peak exercise responses, perception of breathlessness, and quality of life were measured before (baseline) and after (end of study) 12 weeks of exercise training.

RESULTS

As a result of exercise training, VO(2peak) (P=.01) and MSVC (P<.001) increased, with MSVC contributing to a larger proportion of the variability for VO(2peak) at study completion (r=0.57 vs 0.42). Although stroke volume did not increase beyond exercise at 25 W and did not change with exercise training, ventilation decreased during exercise (P<.05), perception of breathing difficulty (P<.05) was reduced, and quality of life was enhanced (P=.008).

CONCLUSIONS

Despite no increase in cardiac output and stroke volume, respiratory muscle endurance improved with exercise training, contributing to increased exercise capacity, decreased breathlessness, and decreased perception of breathlessness. Practical implications can include less frequent rest periods and fatigue, greater confidence, maintenance of independence, and enhanced quality of life.

Mortality, cardiac vagal control and physical training--what's the link?

There is little doubt that regular exercise results in increases in life expectancy and protects against adverse cardiac events in both healthy subjects and patients with cardiovascular disease. The mechanism of action of physical training remains unclear but a variety of evidence points towards an enhancement in cardiac vagal activity protecting against lethal arrhythmias. Just how physical training increases cardiac vagal activity is an area that is ill understood but plausible mechanisms include mediation via angiotensin II or NO. Further research is needed in this area. Exercise training is demanding and difficult, particularly for patients with cardiac disease. If the mechanism of increase in cardiac vagal activity with training can be determined it may be possible to use pharmacological approaches to mimic the effects of exercise with potentially beneficial effects.

Heart failure accompanied by sick euthyroid syndrome and exercise training

Sick euthyroid syndrome is defined as the decrease of serum free triiodothyronine with normal free L-thyroxin and thyrotropin. Its appearance in patients with chronic heart failure is an indicator of severity. Exercise training through a wide variety of mechanisms reverses sick euthyroid syndrome (normalization of free triiodothyronine levels) and improves the ability to exercise. There is a connection during exercise among dyspnea, hyperventilation, fatigue, catecholamines, a decrease in the number and function of beta-blocker receptors, and elevation of serum free triiodothyronine. It is not known whether sick euthyroid syndrome contributes to the development of heart failure or is only an attendant syndrome.

Acute and chronic effects of surgical thromboendarterectomy on exercise capacity and ventilatory efficiency in patients with chronic thromboembolic pulmonary hypertension

OBJECTIVE

To assess acute and chronic effects of surgical thromboendarterectomy on exercise capacity and ventilatory efficiency in patients with chronic thromboembolic pulmonary hypertension (CTEPH).

DESIGN

Cardiopulmonary exercise testing was performed in 20 patients with CTEPH before thromboendarterectomy (baseline), one month after (early phase), and four months after (late phase). Peak oxygen uptake (peak VO(2)) and the ventilatory response to carbon dioxide production (VE-VCO(2) slope) were measured for assessment of exercise capacity and ventilatory efficiency. Right heart catheterisation was performed in all patients before and one month after surgery.

RESULTS

Baseline peak VO(2) decreased and VE-VCO(2) slope increased along with the increase in pulmonary vascular resistance in patients with CTEPH. After thromboendarterectomy, the VE-VCO(2) slope decreased greatly from baseline to the early phase (mean (SD), 50 (9) to 37 (7), p < 0.05) and reached a steady level thereafter. In contrast, a continued increase in peak VO(2) was noted from the early to the late phase (16.9 (4.1) to 21.1 (5.0) ml/kg/min, p < 0.05). The decrease in the VE-VCO(2) slope from baseline to the early phase, but not the increase in peak VO(2), correlated strongly with the decrease in pulmonary vascular resistance after surgery (r = 0.75, p < 0.01).

CONCLUSIONS

Thromboendarterectomy may cause an immediate improvement in ventilatory efficiency, possibly through its beneficial haemodynamic effects. In contrast, exercise capacity may continue to improve towards the late phase, reflecting peripheral adaptation to exercise.

Acute and chronic effects of surgical thromboendarterectomy on exercise capacity and ventilatory efficiency in patients with chronic thromboembolic pulmonary hypertension

OBJECTIVE

To assess acute and chronic effects of surgical thromboendarterectomy on exercise capacity and ventilatory efficiency in patients with chronic thromboembolic pulmonary hypertension (CTEPH).

DESIGN

Cardiopulmonary exercise testing was performed in 20 patients with CTEPH before thromboendarterectomy (baseline), one month after (early phase), and four months after (late phase). Peak oxygen uptake (peakV˙o2) and the ventilatory response to carbon dioxide production (V˙e-V˙co2 slope) were measured for assessment of exercise capacity and ventilatory efficiency. Right heart catheterisation was performed in all patients before and one month after surgery.

RESULTS

Baseline peakV˙o2 decreased andV˙e-V˙co2 slope increased along with the increase in pulmonary vascular resistance in patients with CTEPH. After thromboendarterectomy, theV˙e-V˙co2 slope decreased greatly from baseline to the early phase (mean (SD), 50 (9) to 37 (7), p < 0.05) and reached a steady level thereafter. In contrast, a continued increase in peak V˙o2 was noted from the early to the late phase (16.9 (4.1) to 21.1 (5.0) ml/kg/min, p < 0.05). The decrease in theV˙e-V˙co2 slope from baseline to the early phase, but not the increase in peakV˙o2, correlated strongly with the decrease in pulmonary vascular resistance after surgery (r = 0.75, p < 0.01).

CONCLUSIONS

Thromboendarterectomy may cause an immediate improvement in ventilatory efficiency, possibly through its beneficial haemodynamic effects. In contrast, exercise capacity may continue to improve towards the late phase, reflecting peripheral adaptation to exercise.

Accuracy of estimating exercise prescription intensity in patients with left ventricular systolic dysfunction

PURPOSE

Exercise prescription in patients with left ventricular systolic dysfunction (LVSD) is difficult. Exercising beyond ventilatory threshold (VT) can have negative physiologic effects; therefore, exercise prescribed above VT may be detrimental. A majority of cardiac rehabilitation programs use the Karvonen/heart rate reserve (HRR) method, rating of perceived exertion (RPE), and/or a percentage of oxygen consumption to prescribe exercise intensity. The purpose of this study was to determine if these methods correlate with an exercise intensity below VT in LVSD patients.

METHODS

The authors studied 52 patients (37 males, 15 females; age 52 +/- 13 years; left ventricular ejection fraction 27% +/- 8%) who underwent a symptom-limited cardiopulmonary exercise test and reached VT to determine functional capacity and exercise prescription.

RESULTS

Peak heart rate (HR) as well as HRR derived minimum (60%), midpoint (70%), and maximum (80%) HR were highly correlated (P < 0.001) with HR at VT. Using these three different HR cutoff formulas from HRR, 15% to 62% of patients were prescribed exercise outside the range of VT-HR +/- 10%. The midpoint (70% HRR) best predicted exercise HR in the VT-HR +/- 10% range (73% of patients). Mean oxygen consumption at VT was 83 +/- 9% of peak oxygen consumption. There was no correlation (P < 0.16) between RPE and VT.

CONCLUSIONS

The Karvonen/HRR method failed to estimate HR-VT +/- 10% in a large percentage of patients with LVSD. There was no correlation between RPE and VT. Based on these data, exercise training intensity should ideally be prescribed based on the HR identified at VT using cardiopulmonary exercise testing in patients with LVSD.

Neuroendocrine activation in heart failure is modified by endurance exercise training

OBJECTIVES

The purpose of this study was to determine whether endurance exercise training could buffer neuroendocrine activity in chronic heart failure patients.

BACKGROUND

Neuroendocrine activation is associated with poor long-term prognosis in heart failure. There is growing consensus that exercise may be beneficial by altering the clinical course of heart failure, but the mechanisms responsible for exercise-induced benefits are unclear.

METHODS

Nineteen heart failure patients (ischemic disease; New York Heart Association [NYHA] class II or III) were randomly assigned to either a training group or to a control group. Exercise training consisted of supervised walking three times a week for 16 weeks at 40% to 70% of peak oxygen uptake. Medications were unchanged. Neurohormones were measured at study entry and after 16 weeks.

RESULTS

The training group (n = 10; age = 61 +/- 6 years; EF = 30 +/- 6%) and control group (n = 9; age = 62 +/- 7 years; EF = 29 +/- 7%) did not differ in clinical findings at study entry. Resting levels of angiotensin II, aldosterone, vasopressin and atrial natriuretic peptide in the training and control groups did not differ at study entry (5.6 +/- 1.3 pg/ml; 158 +/- 38 pg/ml; 6.1 +/- 2.0 pg/ml; 37 +/- 8 pg/ml training group vs. 4.8 +/- 1.2; 146 +/- 23; 4.9 +/- 1.1; 35 +/- 10 control group). Peak exercise levels of angiotensin II, aldosterone, vasopressin and atrial natriuretic peptide in the exercise and control groups did not differ at study entry. After 16 weeks, rest and peak exercise hormone levels were unchanged in control patients. Peak exercise neurohormone levels were unchanged in the training group, but resting levels were significantly (p < 0.001) reduced (angiotensin -26%; aldosterone -32%; vasopressin -30%; atrial natriuretic peptide -27%).

CONCLUSIONS

Our data indicate that 16 weeks of endurance exercise training modified resting neuroendocrine hyperactivity in heart failure patients. Reduction in circulating neurohormones may have a beneficial impact on long-term prognosis.

Exercise training in heart failure

Patients with heart failure challenge the clinician with a constellation of difficult clinical, pathophysiologic, and psychologic issues. As a result, until recently, exercise training was not considered a safe and effective treatment strategy to be used in these patients. However, in the past 10 years, data from both randomized and nonrandomized trials showed that regular exercise training in patients with stable Class II and III heart failure can safely improve exercise tolerance, attenuate an overactivated sympathetic nervous system, partially reverse skeletal muscle abnormalities, and enhance health-related quality of life. These outcomes are achievable with a relatively moderate dose of physical activity, such as 30 to 60 minutes of walking or cycling 3 to 5 days per week at an intensity equivalent to 60% to 70% of peak oxygen consumption. Sufficiently powered trials are needed to assess morbidity, mortality, and cost-effectiveness endpoints relative to exercise training in patients with heart failure.

Congestive heart failure: training for a better life

Congestive heart failure (CHF) patients who exercise regularly can increase exercise tolerance, decrease dyspnea and fatigue, reduce the risk of arrhythmias, and improve quality of life. Initial stress testing is important for assessing a patient's physiologic response to exercise and for establishing a target heart rate for an individualized exercise program. Patients may need to begin aerobic exercise with interval training and progress slowly. Strength exercise is also useful. Exercise used along with the customarily prescribed CHF medications improves symptoms more than either modality alone.

Exercise intolerance in congestive heart failure: a lesson in exercise physiology

The current working hypothesis of exercise intolerance in patients with CHF indicates that an initial reduction in cardiac output, secondary to either systolic or diastolic dysfunction, results in a variety of complex and inter-related pathophysiologic alterations in the skeletal muscle, the vasculature, the pulmonary system, and several neurohumoral systems. These numerous compensatory mechanisms, although they work to preserve vital body functions, they ultimately result in exercise intolerance. Thus, the syndrome of CHF provides a unique opportunity to evaluate the role of several fundamental principles of exercise physiology.