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PubMed2005

The BNP concentrations and exercise capacity assessment with cardiopulmonary stress test in patients after surgical repair of Fallot's tetralogy.

Adult patients after surgical repair of Fallot's tetralogy usually present with satisfactory exercise capacity years after the original procedure, though they never tolerate as high levels of exercise as their healthy counterparts. The aim of the study was to assess exercise capacity with cardiopulmonary stress test and BNP levels in adult survivors of surgical repair of Fallot's tetralogy. We studied 60 patients with no or only mild symptoms (including 29 males), at the mean age of 27.6+/-8.2 years at the time of follow-up screening, operated on at the age of 7.5+/-5.3 years. In 34 patients moderate to severe pulmonary regurgitation (PR+) was observed. Control group consisted of 28 healthy volunteers (13 males), aged 28.7+/-5.1 years. Peak oxygen uptake (VO2) in studied group was found to be significantly lower than in control group (24.7+/-5.5 vs. 36.6+/-7.6 ml/kg/min, p=0.00001), VE/VCO2 slope, the marker of respiratory effort, was higher in surgical treatment group as compared to the control group (36.5+/-6.3 vs. 29.7+/-4.7, p=0.004). In patients with PR+, peak VO2% was higher than in PR- individuals (69.6+/-11.8% vs. 58.5+/-12.1%, p=0.0005). The BNP concentration in the studied group (34.8+/-27.1 pg/ml) was higher than in healthy subjects (11.5+/-6.5 pg/ml, p=0.00001). Levels of BNP correlated inversely with peak VO2 (r=-0.286, p=0.03), FVC (r=-0.265 p=0.04) and positively with VE/VCO2 (r=0.361, p=0.005). Additionally the levels of BNP correlated positively with the age of patients at the time of surgical repair (r=0.250, p=0.04). We concluded that exercise capacity in adults after repair of Fallot's tetralogy, especially those PR+, was lower than in healthy volunteers. Concentrations of BNP in surgical treatment survivors were higher and correlated well with cardiopulmonary stress study parameters.

Adolescent↗

PubMed1992

Role of neurohumoral control of the circulation in determining exercise capacity in patients with heart failure.

The weak relationship between left ventricular function and exercise capacity in heart failure has stimulated interest in neurohumoral mechanisms as possibly contributing to exercise intolerance. Although chronic activation of neuroendocrine systems is characteristic of heart failure and is accompanied by impaired reflex responsiveness to physiologic stimuli, data from clinical trials do not support the hypothesis that the abnormal neurohumoral state is directly related to exercise intolerance. Thus, these systems may play an important role in the natural history of the disease and its high mortality, but they may not be critical to the impaired exercise capacity.

Blood Circulation↗

PubMed1997

The influence of muscle mass, strength, fatigability and blood flow on exercise capacity in cachectic and non-cachectic patients with chronic heart failure.

BACKGROUND: The influence of age, skeletal muscle function and peripheral blood flow on exercise capacity in chronic heart failure patients is controversial, possibly due to variations in skeletal muscle atrophy. METHODS AND RESULTS: To assess predictors of exercise capacity in patients with clinical cardiac cachexia, we studied 16 cachectic and 39 non-cachectic male chronic heart failure patients of similar age and ejection fraction. All cachectic patients were wasted (% ideal body weight: 81.2 +/- 1.9 vs 105.2 +/- 2.1, P < 0.0001, mean +/- SEM) and had documented weight loss (5-30 kg). Peak oxygen consumption (14.9 +/- 1.4 vs 16.3 +/- 0.6 ml.kg-1, min-1, resting and peak blood flow (plethysmography) and 20 min fatigability (% baseline strength) were all similar between the two groups. Quadriceps strength, muscle size (all P < 0.0001), strength per unit muscle (right: P < 0.05: left: P < 0.001) and 5 min fatigability (P < 0.05) were all lower in cachectic patients. In non-cachectic patients, age (R = 0.48) and quadriceps strength (R = 0.43, all P < 0.01) predicted peak oxygen consumption. Only in cachectic patients did peak blood flow predict peak oxygen consumption significantly (R = 0.72, P = 0.005), whereas age and strength did not. Similar findings were confirmed using other previously published definitions of cardiac cachexia. CONCLUSIONS: The predictors of exercise capacity change with the development of cardiac cachexia from age and strength to peak blood flow. This shift may be caused by additional endocrine or catabolic, abnormalities active in end stage heart failure.

Adult↗

PubMed2005

Inhaled beta-agonists improve lung function but not maximal exercise capacity in cystic fibrosis.

BACKGROUND: To investigate the effects of inhaled beta-agonists on sub-maximal and maximal exercise capacity, breathing pattern, dyspnoea, leg-discomfort and spirometry in patients with cystic fibrosis (CF). OBJECTIVES: Eight patients performed two maximal incremental cycle-ergometry tests on separate days with inhaled placebo or salbutamol (600 microg) administered before each test in a randomized, double-blind, placebo-controlled crossover trial. Primary outcomes were exercise duration (Exdur) in seconds (s) and maximal oxygen uptake (VO2max) in litres/minute (L/min). Forced expiratory volume in 1 s (FEV1) was measured immediately pre-inhaler, post-inhaler and post-exercise. Dyspnoea and leg-discomfort were assessed post-exercise. RESULTS: Within-day FEV1 comparisons demonstrated that the placebo test day FEV1 improved significantly post-exercise (0.11 L, p<0.05) and the salbutamol test day FEV1 improved significantly post-inhaler (0.22 L, p<0.001) and post-exercise (0.07 L, p<0.01). Between-day FEV1 comparisons demonstrated significant improvements in post-inhaler (0.17 L, p<0.05) and post-exercise (0.13 L, p<0.05) FEV1 following salbutamol. Sub-maximal and maximal exercise showed no significant difference as shown by Exdur (547+/-154 s vs. 529+/-127 s) and VO2max (1.9+/-0.5 L/min vs. 1.9+/-0.6 L/min). No significant change in breathing pattern, dyspnoea or leg-discomfort was detected. The study had a power of 92% to detect a 10% improvement in Exdur. CONCLUSIONS: In adults with CF, salbutamol improves post-exercise FEV1 and is safe when administered immediately before exercise but does not improve exercise capacity, exercise-induced dyspnoea or leg-discomfort.

Administration, Inhalation↗

PubMed2006

Effects of exercise training on cardiac performance, exercise capacity and quality of life in patients with heart failure: a meta-analysis.

BACKGROUND: Despite major advances in pharmacological treatment of chronic heart failure (CHF), a number of patients still suffer from dyspnoea, fatigue, diminished exercise capacity and poor quality of life. It is in this context that exercise training is being intensively evaluated for any additional benefit in the treatment of CHF. AIMS: To determine the effect of exercise training in patients with CHF on cardiac performance, exercise capacity and health-related quality of life. A meta-analysis was performed to obtain this goal. METHODS AND RESULTS: After including 35 randomised controlled trials, the methodological quality of each study was assessed, summary effect sizes (SESs) and the concomitant 95% confidence intervals (95% CI) were calculated for each outcome. Quantitative analysis showed statistically significant SESs, at rest, for diastolic blood pressure and end-diastolic volume. During maximal exercise, significant SESs were found for systolic blood pressure, heart rate, cardiac output, peak oxygen uptake, anaerobic threshold and 6-min walking test. The Minnesota Living with Heart Failure Questionnaire improved by an average of 9.7 points. CONCLUSIONS: Exercise training has clinically important effects on exercise capacity and HRQL, and may have small positive effects on cardiac performance during exercise.

Exercise↗

PubMed1995

Improvements in exercise capacity and dyspnoea by inhaled anticholinergic drug in elderly patients with chronic obstructive pulmonary disease.

To test the effects of the inhaled anticholinergic drug, oxitropium bromide (OTB), on exercise capacity and dyspnoea in elderly patients (more than 75 years old) with chronic obstructive pulmonary disease (COPD), we performed cycle exercise testing on 12 elderly patients with COPD [mean age 78.7 (SD 1.1) years; FEV1% 41.3 (2.0)%] as well as 12 middle-aged COPD patients [mean age 60.1 (1.0) years; FEV1% 38.9 (2.4)%] before and after inhalation of OTB or placebo in a double-blind and placebo-controlled design. Spirometry was repeated immediately before and 30 min after OTB or placebo inhalation. Dyspnoea was quantitatively evaluated using the slope of the regression line between Borg scale and oxygen uptake (VO2) during exercise (Borg scale slope: BSS). After OTB inhalation, spirometric indices, exercise capacity as indexed by maximal VO2, and dyspnoea index (BSS) were improved compared with pre-inhalation value in both the elderly and middle-aged patients. The magnitude of improvements in these indices in the elderly patients was not different from that in the middle-aged. We conclude that the inhaled anticholinergic drug produces useful improvements in dyspnoea and exercise capacity in both elderly and middle-aged COPD patients.

Administration, Inhalation↗

PubMed1996

Coronary flow reserve and exercise capacity in hypertrophic cardiomyopathy.

The aim of this study was to evaluate the relation of coronary flow velocity (CFV) and coronary flow reserve (CFR) to exercise capacity in ten verapamil-treated patients with hypertrophic cardiomyopathy (HC). Using Doppler transesophageal echocardiography, we assessed diastolic CFV in the proximal left anterior descending coronary artery at baseline and after administering 0.56 mg/kg intravenous dipyridamole. The CFR was calculated as the post-dipyridamole/baseline diastolic CFV ratio. A maximal symptom-limited exercise treadmill test was performed according to a modified Bruce protocol and the exercise capacity was expressed as metabolic equivalents. The mean value for baseline diastolic CFV was 59 +/- 27 cm/s; this increased after dipyridamole to 134 +/- 57 cm/s. The CFR was 2.37 +/- 0.67. Baseline diastolic CFV correlated negatively with both exercise duration (r = -0.69; P < 0.05) and value for metabolic equivalents (r = -0.70; P < 0.05). CFR was weakly and non-significantly related to exercise duration (r = 0.40; P > 0.05) and to the value for metabolic equivalents (r = 0.32; P > 0.05). Shortening of exercise time and decreasing metabolic equivalents were correlated with increased baseline diastolic CFV. Dipyridamole-assessed CFR, was weakly related to parameters of exercise capacity.

Adult↗

PubMed1988

The importance of different atrioventricular intervals for exercise capacity.

In order to determine whether different atrioventricular intervals influence the maximal exercise capacity, 15 patients with second degree or complete atrioventricular block and no signs of left ventricular failure were studied. They all had atrioventricular synchronous pacemakers. Maximal exercise tests (sitting bicycle ergometry) were performed at four different atrioventricular intervals (50, 100, 150, and 200 ms) and during rate-matched asynchronous ventricular pacing. The patients thereby served as their own controls. Ventricular rate, maximal oxygen uptake and minute ventilation were measured and perceived exertion estimated every minute. Different atrioventricular intervals did not affect the maximal exercise capacity, the maximal oxygen uptake, the perceived exertion or minute ventilation. Since the results were similar during atrioventricular synchronous pacing at various atrioventricular intervals and on rate-matched asynchronous ventricular pacing, this study supports previous findings that the important factor for maximal physical performance is not a preserved atrioventricular synchronization but the ability to increase the ventricular rate.

Adaptation, Physiological↗

PubMed2000

Effect of bisoprolol and atenolol on endurance exercise capacity in healthy men.

OBJECTIVES: To compare the effects of a highly beta1-selective adrenoceptor antagonist bisoprolol with those of atenolol and placebo on endurance exercise capacity in young, healthy male volunteers. DESIGN: Twelve subjects randomly received oral placebo, atenolol (100 mg/day) or bisoprolol (10 mg/day) for 3 weeks, following a double-blind cross-over design. METHODS: At the end of each period, the subjects performed an endurance exercise test on the bicycle ergometer at 70% of maximal aerobic power. Cardiac output was measured by means of an automated CO2-rebreathing method. Venous blood was sampled before, during and after exercise. RESULTS: Exercise duration was not significantly different between the two drugs tested. Total exercise duration was significantly reduced by bisoprolol (-19.4 +/- 6.7%, P< 0.01) (mean +/- SEM) and by atenolol (-29.8 +/- 6.6%, P< 0.001), compared with placebo. Atenolol and bisoprolol were equally effective in lowering resting plasma renin activity, heart rate and systolic blood pressure. Resting and exercise stroke volume were significantly increased by both drugs, so that cardiac output was not significantly affected. Both drugs induced significant decreases in plasma-free fatty acid concentrations during recovery and blunted the exercise-induced increase. There were no significant relationships between the reduction of exercise duration and the haemodynamic changes or the degree of impairment of the exercise-induced increase in free fatty acid release resulting from beta-blockade. CONCLUSIONS: It is concluded that both drugs affect endurance exercise capacity in young, normotensive men, with a tendency to a smaller reduction during bisoprolol treatment. Haemodynamic variables are unlikely to be involved in the reduction of endurance exercise capacity. The role of the reduced availability of plasma free fatty acids remains unclear.

Adrenergic beta-Antagonists↗

PubMed1997

Left atrial function as a reliable predictor of exercise capacity in patients with recent myocardial infarction.

STUDY OBJECTIVE: To examine the relation between left atrial (LA) function and exercise performance. DESIGN AND SETTING: Retrospective study at a referral cardiopulmonary exercise laboratory in a university hospital. PATIENTS: Forty-one patients with recent myocardial infarction. INTERVENTIONS: M-mode echocardiography and cardiopulmonary exercise testing combined with radionuclide ventriculography. MEASUREMENTS AND RESULTS: Hemodynamic measurements were obtained at rest and peak exercise. LA fractional shortening at rest was used as an index of global LA function. LA fractional shortening had fair correlations with peak oxygen consumption (r=0.67, p<0.01) and exercise duration (r=0.71, p<0.01). Although there were no significant relations between LA fractional shortening and hemodynamic measurements at rest, LA fractional shortening was positively related to peak cardiac output (r=0.61, p<0.01) and peak stroke volume (r=0.57, p<0.01), and negatively related to peak pulmonary arterial wedge pressure (r=-0.44, p<0.05). In addition, LA fractional shortening correlated significantly with an increase in left ventricular (LV) end-diastolic volume from rest to peak exercise (r=0.48, p<0.02), but did not correlate with the changes in ejection fraction and end-systolic volume during exercise. An increase in LV end-diastolic volume during exercise was significantly related to peak oxygen consumption (r=0.46, p<0.02), peak cardiac output (r=0.60, p<0.01), and peak stroke volume (r=0.53, p<0.01), whereas the changes in ejection fraction and end-systolic volume during exercise were not related to these indexes. CONCLUSIONS: Exercise capacity and LV performance during exercise were mainly dependent on LV diastolic filling rather than systolic contraction during exercise. LA fractional shortening at rest reflected LV diastolic filling during exercise and, therefore, predicted cardiac output and stroke volume responses to exercise and exercise capacity in patients with recent myocardial infarction.

Adult↗

PubMed2001

Relationship between doppler-derived left ventricular diastolic function and exercise capacity in patients with myocardial infarction.

Doppler echocardiographic indices of left ventricular (LV) diastolic function are widely used to evaluate the cardiac function of patients with cardiac disease. However, there have been few reports about the relationship between Doppler indices and exercise capacity and so 44 patients with myocardial infarction were investigated by cardiopulmonary exercise testing and 2-D and Doppler echocardiography. Diastolic performance was assessed using Doppler transmitral flow velocity and pulmonary venous flow velocity. The ratio of peak E wave velocity and peak A wave velocity (E/A) correlated with peak oxygen consumption (peak Vo2) (R=0.72), and there was a negative correlation between the deceleration time of E velocity (Dct) and peak Vo2 or anaerobic threshold (AT) (R=-0.65, -0.62, respectively). The ratio of peak S wave velocity and peak D wave velocity (S/D) negatively correlated with peak Vo2 (R=-0.58). Left ventricular ejection fraction did not correlate to exercise capacity. These results suggest that the Doppler echocardiographic indices of LV diastolic function correlate with exercise capacity in patients with mild cardiac dysfunction.

Aged↗

PubMed2001

Exercise capacity in lean versus obese women.

The aim of this study was to assess the nature and magnitude of the differences in submaximal and maximal exercise capacity parameters between lean and obese women. A total of 225 healthy obese women 18-65 years (BMI> or=30 kg/m(2)) and 81 non-athletic lean women (BMI< or=26 kg/m(2)) were selected. Anthropometric measurements (weight and height), body composition assessment (bioelectrical impedance method) and a maximal exercise capacity test on a bicycle ergometer were performed. Oxygen uptake (VO(2)), carbon dioxide production (VCO(2)), expired ventilation (VE), respiratory quotient (RQ), breathing efficiency (VE/VO(2)), mechanical efficiency (ME) and anaerobic threshold (AT) were calculated. At a submaximal intensity load of 70 W, VO(2) (l/min) was larger in the obese women and was already 78% of their peak VO(2), whereas in the non-obese it was only 69% (P=0.0001). VE (l/min) was larger, VE/VO(2) did not differ and ME was lower in obese compared to the lean women. AT occurred at the same percentage of peak VO(2) in both lean and obese women. At peak effort, achieved load, terminal VO(2) (l min(-1) kg(-1)), VE, heart rate, RQ respiratory exchange ratio and perceived exertion were lower in obese subjects compared to the non-obese. Obese subjects mentioned significantly more musculoskeletal pain as a reason to end the test, whereas in lean subjects it was leg fatigue. Lean women recovered better as after 2 min they were already at 35% of the peak VO(2), whereas in the obese women it was 47% (P=0.0001). Our results confirm that exercise capacity is decreased in obesity, both at submaximal and peak intensity, and during recovery. Moreover, at peak effort musculoskeletal pain was an important reason to end the test and not true leg fatigue. These findings are important when designing exercise programs for obese subjects.

Adult↗

PubMed2000

Clinical predictors of morbidity and mortality in patients with myocardial infarction or revascularization who underwent cardiac rehabilitation, and importance of diabetes mellitus and exercise capacity.

This investigation was a prospective, follow-up study to assess whether baseline clinical and investigational parameters were predictors of cardiovascular morbidity and mortality in patients enrolled into the cardiac rehabilitation program. A cohort of 418 patients (70% were men) with coronary heart disease was followed up 3.2 +/- 1.1 years. Two hundred twenty-seven of them (54%) had a recent myocardial infarction (MI), with a thrombolytic rate of 54%. Percutaneous transluminal coronary angioplasty (PTCA) was performed in 45% of patients. The covariates assessed include age, gender, smoking habit, body mass index, the presence of hypertension or diabetes mellitus, exercise habit, site and severity of MI, status of thrombolytic therapy, peak creatine phosphokinase, plasma lipid profiles, ejection fraction, PTCA performed, number of diseased coronary arteries, and exercise capacity. Low-density lipoprotein cholesterol decreased significantly (3.2 +/- 1.0 vs 2.7 +/- 0.7 mmol/L, p < 0.001). The cumulative mortality was 13%. In a univariate model, the parameters that significantly predict mortality included older age, diabetes, low exercise capacity (< or = 4 metabolic equivalents) 3-vessel disease, those without PTCA performed, and a low ejection fraction. In the Cox proportional-hazards model analysis, the independent factors were coexisting diabetes (chi-square 6.1, p = 0.01) and a low metabolic equivalent (chi-square 6.5, p = 0.01). One hundred six patients were rehospitalized for nonfatal cardiovascular events that included unstable angina (48%), heart failure (21%), acute MI (6%), symptomatic arrhythmia (6%), and severe hypertension (1%). Factors that independently predicted rehospitalization were low exercise capacity (p = 0.02) and the presence of diabetes (chi-square 4.8, p = 0.03). Diabetes was also associated with more episodes of hospital admission (2.3 +/- 2.1 vs 1.6 +/- 1.4, p = 0.04) and a longer cumulative hospital stay (25.5 +/- 34.6 vs 11.4 +/- 19.6 days, p = 0.02). Thus, in patients with MI or after PTCA receiving conventional medical therapy, the cardiac rehabilitation program should focus on aggressive diabetic control and enhancement of exercise capacity.

Aged↗

PubMed2005

Angiotensin receptor blockade and exercise capacity in adults with systemic right ventricles: a multicenter, randomized, placebo-controlled clinical trial.

BACKGROUND: Pharmacological blockade of the renin-angiotensin system improves exercise tolerance in patients with left ventricular dysfunction, yet its impact on patients with systemic right ventricles (RVs) remains unknown. METHODS AND RESULTS: A multicenter, randomized, double-blind, placebo-controlled, crossover clinical trial was performed to assess the effects of losartan on exercise capacity and neurohormonal levels in patients with systemic RVs. Of 29 patients studied (age, 30.3+/-10.9 years), 21 had transposition of the great arteries with a Mustard baffle, and 8 had congenitally corrected transposition of the great arteries. Baseline values were as follows: VO2max, 29.8+/-5.6 mL.kg(-1).min(-1) (73.5+/-12.9% predicted value); RV ejection fraction, 41.6+/-9.3%; N-terminal pro brain natriuretic peptide (NT-proBNP), 257.7+/-243.4 pg/mL (normal <125 pg/mL); and angiotensin II, 5.7+/-4.9 pg/mL (normal <5.0 pg/mL). Comparing losartan to placebo showed no differences in VO2max (29.9+/-5.4 versus 29.4+/-6.2 mL.kg(-1).min(-1); P=0.43), exercise duration (632.3+/-123.0 versus 629.9+/-140.7 seconds; P=0.76), and NT-proBNP levels (201.2+/-267.8 versus 229.7+/-291.5 pg/mL; P=0.10), despite a trend toward increased angiotensin II levels (15.2+/-13.8 versus 8.8+/-12.5 pg/mL; P=0.08). CONCLUSIONS: In adults with systemic RVs, losartan did not improve exercise capacity or reduce NT-proBNP levels. Minimal baseline activation of the renin-angiotensin system may explain this lack of benefit and imply an alternative pathophysiological mechanism for the progressive ventricular dysfunction and impaired exercise capacity observed in such patients.

Adult↗

PubMed1990

Exercise capacity and quality of life in the treatment of heart failure.

In a double-blind study comparing two active treatments (digoxin and xamoterol) and placebo in patients with heart failure, improvements in exercise capacity and quality of life were observed in all three groups, with no significant differences. The substantial benefits seen in the placebo group were probably the result of increased attention from the medical and research staff and suggest the therapeutic value of special heart failure clinics. The relationship between exercise and symptomatic/functional status has been unclear. We developed quantitative measures of quality-of-life variables and examined their relationship with exercise capacity. There were significant relationships between change in exercise duration and changes in breathlessness, tiredness, chest pain, walking difficulty, rate of walking, difficulty with daily tasks, speed of daily tasks, mood, and sleeping. This study confirms the validity of measuring change in exercise capacity and demonstrates that specific measurements of quality of life make an important contribution to the evaluation of the treatment of heart failure.

Adult↗

PubMed1982

[Comparison of exercise capacity with resting left ventricular function evaluated by various non-invasive methods in patients with old myocardial infarction].

The purpose of this study was to investigate the relationship between exercise capacity and resting left ventricular function assessed by several non-invasive methods in patients with old myocardial infarction. Subjects were 25 male patients whose endpoint was either dyspnea or general fatigue at the symptom-limited maximal graded treadmill exercise test according to Bruce protocol. The indices obtained by non-invasive cardiac examinations included left ventricular fractional shortening (% FS), scintigraphic infarct size (% SIS) by 201Tl myocardial scintigraphy and PEP/ET (so-called Weissler's index). A significant correlation of exercise duration with % FS (r = 0.67, p less than 0.001) or with % SIS (r = -0.55, p less than 0.02) indicated that the more was impaired resting left ventricular function, the more was decreased exercise capacity. Also, a significant correlation of systolic blood pressure at the end-point in exercise test with % FS (r = 0.58, p less than 0.005) or with % SIS (r = 0.69, p less than 0.001) indicated that inadequate blood pressure response might be partially attributed to impaired left ventricular function during exercise. The response of heart rate at the Bruce protocol stage I correlated with % FS (r = -0.67, p less than 0.001) and with % SIS (r = 0.53, p less than 0.02), respectively. These findings may be interpreted as chronotropic compensatory mechanism for limited stroke volume during exercise in patients with imparied left ventricular function. Thus, it was concluded that resting left ventricular function assessed by non-invasive cardiac examinations may predict exercise capacity prior to the test to some extent. These informations can be utilized for the decision of the planning at cardiac rehabilitation and also for the guidance in daily activities. Additionally, low level exercise test with treadmill is considered to be valuable for screening cases with impaired left ventricular function in old myocardial infarction.

Adult↗

PubMed1985

The ability of a submaximal exercise test to predict maximal exercise capacity in patients with heart failure.

We investigated the ability of a submaximal exercise test to predict the maximal aerobic potential and hence exercise capacity of patients with chronic heart failure. Heart rate, oxygen consumption and carbon dioxide production were measured continuously during treadmill exercise in 29 patients with chronic heart failure (NYHA Class II-III). The anaerobic threshold was determined as the oxygen consumption at which carbon dioxide production increased non-linearly relative to oxygen consumption. Maximal oxygen consumption could not be predicted from the heart rate response to submaximal exercise. Oxygen consumption at the anaerobic threshold (28 patients) and at a respiratory quotient of 1 (23 patients) did predict maximal oxygen consumption (r = 0.93, r = 0.88, respectively). Measurement of oxygen consumption during submaximal exercise can be used to assess maximal exercise capacity in patients with heart failure.

Adult↗

PubMed2001

Short-term oral administration of L-arginine improves hemodynamics and exercise capacity in patients with precapillary pulmonary hypertension.

We sought to assess the effects of oral supplementation of L-arginine, the precursor of nitric oxide (NO), on hemodynamics and exercise capacity in patients with pulmonary hypertension. Acute hemodynamic responses to oral L-arginine (0.5 g/10 kg body weight) or placebo were examined in 19 patients with primary or precapillary secondary pulmonary hypertension. Cardiopulmonary exercise tests were performed to measure peak oxygen consumption (peak V O(2)) and the ventilatory response to carbon dioxide production (V E-V CO(2) slope) before and 1 wk after treatment with L-arginine (1.5 g/10 kg body weight/d) or placebo. Oral supplementation of L-arginine significantly increased plasma L-citrulline, which indicated enhancement of NO production. Supplemental L-arginine produced a 9% decrease in mean pulmonary arterial pressure (53 +/- 4 to 48 +/- 4 mm Hg, p < 0.05) and a 16% decrease in pulmonary vascular resistance (14.8 +/- 1.5 to 12.4 +/- 1.4 Wood units, p < 0.05). L-arginine modestly decreased mean systemic arterial pressure (92 +/- 4 to 87 +/- 3 mm Hg, p < 0.05). A 1-wk supplementation of L-arginine resulted in a slight increase in peak V O(2) (831 +/- 88 to 896 +/- 92 ml/min, p < 0.05) and a significant decrease in the V E- V CO(2) slope (43 +/- 4 to 37 +/- 3, p < 0.05) without significant systemic hypotension. Hemodynamics and exercise capacity remained unchanged during placebo administration. These results suggest that oral supplementation of L-arginine may have beneficial effects on hemodynamics and exercise capacity in patients with precapillary pulmonary hypertension.

Administration, Oral↗