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Background: Equations to predict maximum heart rate (HR(max)) in heart failure (HF) patients receiving β-adrenergic blocking (BB) agents do not consider the cause of HF. We determined equations to predict HR(max) in patients with ischemic and nonischemic HF receiving BB therapy., Methods and Results: Using treadmill cardiopulmonary exercise testing, we studied HF patients receiving BB therapy being considered for transplantation from 1999 to 2010. Exclusions were pacemaker and/or implantable defibrillator, left ventricle ejection fraction (LVEF) >50%, peak respiratory exchange ratio (RER) <1.00, and Chagas disease. We used linear regression equations to predict HR(max) based on age in ischemic and nonischemic patients. We analyzed 278 patients, aged 47 ± 10 years, with ischemic (n = 75) and nonischemic (n = 203) HF. LVEF was 30.8 ± 9.4% and 28.6 ± 8.2% (P = .04), peak VO(2) 16.9 ± 4.7 and 16.9 ± 5.2 mL kg(-1) min(-1) (P = NS), and the HR(max) 130.8 ± 23.3 and 125.3 ± 25.3 beats/min (P = .051) in ischemic and nonischemic patients, respectively. We devised the equation HR(max) = 168 - 0.76 × age (R(2) = 0.095; P = .007) for ischemic HF patients, but there was no significant relationship between age and HR(max) in nonischemic HF patients (R(2) = 0.006; P = NS)., Conclusions: Our study suggests that equations to estimate HR(max) should consider the cause of HF., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Background: Heart failure (HF) is associated with resting increased peripheral and central chemosensitivity which may correlate with an increased ventilatory response to exercise. However, its sensitivity in HF during exercise was never really reported., Objective: We tested if stimulation of central and peripheral chemoreceptors in HF patients could modulate ventilatory, chronotropic, and neurohormonal response during submaximal exercise., Methods: We investigated central and peripheral chemosensitivity in 15 HF and 7 control (C) comparing response through three 6 minute walking tests conducted in a treadmill with : room air, hypoxia, and hypercapnia (in a randomic order)., Results: RR at room air C and HF was 17±2 and 22±2 (p<.0001); at hypoxia 17±1 and 23±2 (p<.02); at CO25% was 20±2 and 22±5 (p<.02). Tidal volume (TV) at room air was 1.25±0.17 and 1.08±0.19 (p<.01); at hypoxia 1.65±0.34 and 1.2±0.2 (p<.0001); at CO25% 1.55±0.46 and 1.29±0.39 (p<.0001). At rest the increment in HF was higher for VE (C 33±40%, HF 62±94%, p<.01), HR(C 7±10%, HF 10±10%, p<0.05) at rest. During hypoxia exercise increment in HF was higher for RR (C 1±4, HF 11±6,p<.05), HR (C 12±2, HF 14±3, p<.05), VE/VO₂ (C -4±18%, HF 24±21%, p<.01), HR/VO₂ (C -26±11%, HF 11±5%, p<.01), VE/WD (C 36±10%, 46±14, p<.05%) and HR/WD (C 18±8%, HF 29±11, p<.01). During HF hypoxia exercise NO reduced, and IL-6, aldosterone levels increased. Neurohormonal levels unchanged in C., Conclusion: Exercise peripheral and central chemosensitivity are increased in HF and may modulate respiratory pattern, cardiac chronotropic, and neurohormonal activity during exercise.

Objective: We sought to evaluate the neurohormonal activity in heart transplant recipients and compare it with that in heart failure patients and healthy subjects during rest and just after a 6-minute walking test., Introduction: Despite the improvements in quality of life and survival provided by heart transplantation, the neurohormonal profile is poorly described., Methods: Twenty heart transplantation (18 men, 49+/-11 years and 8.5+/-3.3 years after transplantation), 11 heart failure (8 men, 43+/-10 years), and 7 healthy subjects (5 men 39+/-8 years) were included in this study. Blood samples were collected immediately before and during the last minute of the exercise., Results: During rest, patients' norepinephrine plasma level (659+/-225 pg/mL) was higher in heart transplant recipients (463+/-167 pg/mL) and healthy subjects (512+/-132), p<0.05. Heart transplant recipient's norepinephrine plasma level was not different than that of healthy subjects. Just after the 6-minute walking test, the heart transplant recipient's norepinephrine plasma level (1248+/-692 pg/mL) was not different from that of heart failure patients (1174+/-653 pg/mL). Both these groups had a higher level than healthy subjects had (545+/-95 pg/mL), p<0.05., Conclusion: Neurohormonal activity remains increased after the 6-minute walking test after heart transplantation.

Background: One way of defining an individual's heart effort is to calculate the maximum heart rate to be expected given their age, but the reinnervation seen in patients who have received heart transplants makes for different calculations from patients who have suffered heart failure. The purpose of this study is to evaluate heart rate dynamics (rest, peak and percentage of predicted heart rate for age) in heart transplant patients compared to optimized beta-blocked heart failure patients during a treadmill cardiopulmonary exercise test., Methods: Twenty two (81% male, 46 +/- 12 years) sedentary heart failure patients and 15 (47% male, 44 +/- 13 years) sedentary heart transplant patients performed a treadmill cardiopulmonary exercise test between 10 am and 3 pm. Heart failure optimization was considered 50 mg/day or more of carvedilol, with a resting heart rate of between 50 and 60 bpm., Results: Basal heart rate was lower in heart failure patients (58 +/- 5 bpm) compared to heart transplant patients (93 +/- 11 bpm; p < 0.0001). Similarly, the peak heart rate (percentage of the maximum predicted for age) was lower in heart failure patients (60 +/- 13%) compared to heart transplant patients (80 +/- 12; p < 0.0001). Maximum respiratory exchange ratio did not differ between the groups (1.05 +/- 0.06 in heart failure patients and 1.11 +/- 0.1 in heart transplant patients; p = 0.08). Moreover, the heart rate reserve between heart failure (49 +/- 22) and heart transplantation (46 +/- 16%) was not different (p = 0.644)., Conclusions: No patient reached the maximum heart rate predicted for their age during a treadmill cardiopulmonary exercise test. The heart rate reserve was similar between groups. A heart rate increase in heart transplant patients during cardiopulmonary exercise test of more than 80% of the maximum age-adjusted value should be considered an effort near the maximum.

Background: Calculating the maximum heart rate for age is one method to characterize the maximum effort of an individual. Although this method is commonly used, little is known about heart rate dynamics in optimized beta-blocked heart failure patients., Aim: The aim of this study was to evaluate heart rate dynamics (basal, peak and % heart rate increase) in optimized beta-blocked heart failure patients compared to sedentary, normal individuals (controls) during a treadmill cardiopulmonary exercise test., Methods: Twenty-five heart failure patients (49+/-11 years, 76% male), with an average LVEF of 30+/-7%, and fourteen controls were included in the study. Patients with atrial fibrillation, a pacemaker or noncardiovascular functional limitations or whose drug therapy was not optimized were excluded. Optimization was considered to be 50 mg/day or more of carvedilol, with a basal heart rate between 50 to 60 bpm that was maintained for 3 months., Results: Basal heart rate was lower in heart failure patients (57+/-3 bpm) compared to controls (89+/-14 bpm; p<0.0001). Similarly, the peak heart rate (% maximum predicted for age) was lower in HF patients (65.4+/-11.1%) compared to controls (98.6+/-2.2; p<0.0001). Maximum respiratory exchange ratio did not differ between the groups (1.2+/-0.5 for controls and 1.15+/-1 for heart failure patients; p=0.42). All controls reached the maximum heart rate for their age, while no patients in the heart failure group reached the maximum. Moreover, the % increase of heart rate from rest to peak exercise between heart failure (48+/-9%) and control (53+/-8%) was not different (p=0.157)., Conclusion: No patient in the heart failure group reached the maximum heart rate for their age during a treadmill cardiopulmonary exercise test, despite the fact that the percentage increase of heart rate was similar to sedentary normal subjects. A heart rate increase in optimized beta-blocked heart failure patients during cardiopulmonary exercise test over 65% of the maximum age-adjusted value should be considered an effort near the maximum. This information may be useful in rehabilitation programs and ischemic tests, although further studies are required.

Background: Studies have demonstrated that peak oxygen consumption (peak VO2) and the VE/VCO2 slope are predictors of survival in patients with heart failure (HF). However, with the advent of betablockers in the treatment of HF, the prognostic values of peak VO2 and VE/VCO2 slope have not been fully established., Objective: To evaluate the effect of betablocker use on the prognostic value of peak VO2 and VE/VCO2 slope in patients with HF., Methods: We studied 391 patients with heart failure, aged 49 +/- 14 years and presenting a left ventricular ejection fraction of 38 +/- 10%. The total number of patients that used (Group I - GI) or did not use (Group II - GII) betablockers was 229 and 162, respectively. All patients were submitted to a cardiopulmonary stress test on a treadmill, using the Naughton protocol., Results: A peak VO2 < or = 10 ml x kg(-1) x min(-1) identified high-risk patients, whereas values > 16 ml x kg(-1) min(-1) categorizes patients with a better mid-term prognosis. Peak VO2 values between > 10 and < or = 16 ml x kg(-1) x min(-1) indicated moderate risk for cardiac event in four years of follow up. The betablocker use significantly reduced the VE/VCO2 slope in patients with HF. The prognostic value of the VE/VCO2 slope < 34 in the group using betablocker can reflect the impact of the drug on this cardiorespiratory variable., Conclusion: A low peak VO2 and an elevated VE/VCO2 slope are strong and independent predictors of cardiac events in HF. Thus, both variables remain important survival predictors in patients with HF, especially at the age of betablockers.

Background: Peak oxygen consumption and resting left ventricular ejection fraction (LVEF) are independent predictors of survival in adult heart failure (HF) patients., Aim: To evaluate these factors in children., Methods: We prospectively studied 31 children with NYHA class I to III HF (mean LVEF 26+/-10%; mean age 8.6+/-1.9 years). All had dilated cardiomyopathy and were awaiting heart transplantation. A cardiopulmonary treadmill exercise test was performed and LVEF determined by radionuclide ventriculography., Results: During a median follow-up of 1282 days, 20 children reached at least one end-point (death or heart transplantation). Clinical data from the 11 children without events and the 20 children with events are as follows: NYHA class 1+/-0 vs. 2+/-0.9 (p<0.01); SBP 118+/-17 vs. 102+/-16 (p=0.01); DBP 70+/-10 vs. 61+/-10 (p=0.02); heart rate 165+/-22 vs. 148+/-22 (NS); double-product 19+/-4 vs. 15+/-4 (p=0.01); end-tidal carbon dioxide tension (PetCO2) 35+/-5 vs. 30+/-6 (NS); oxygen consumption (VO2) 22+/-5.4 vs. 18.3+/-5.7 (NS); exercise time 19+/-4 vs. 13+/-6 (p<0.003), and LVEF 31+/-8 vs. 22+/-10 (p=0.02). These variables all correlated with prognosis on univariate analysis. In multivariate analysis, only decreasing exercise time and LVEF were predictive of events during follow-up (p<0.001 and 0.04)., Conclusion: These findings suggest that reduction in LVEF and exercise tolerance in children with heart failure is predictive of functional status.

Introduction: The six-minute walk test (6WT) has been proposed to be a submaximal test, but could actually demand a high level of exercise intensity from the patient, expressed by a respiratory quotient >1.0, following the guideline recommendations. Standardizing the 6WT using the Borg scale was proposed to make sure that all patients undergo a submaximal walking test., Purpose: To test the reproducibility of the six-minute treadmill cardiopulmonary walk test (6CWT) using the Borg scale and to make sure that all patients undergo a submaximal test., Methods: Twenty-three male heart failure patients (50+/-9 years) were included; these patients had both ischemic (5) and non-ischemic (18) heart failure with a left ventricle ejection fraction of 23+/-7%, were diagnosed as functional class NYHA II-III and were undergoing optimized drug therapy. Patients were guided to walk at a pace between "relatively easy and slightly tiring" (11 and 13 on Borg scale). The 6CWT using the Borg scale was performed two times on a treadmill with zero inclination and patient control of speed with an interval of 24 hours. During the sixth minute, we analyzed ventilation (VE, L/min), respiratory quotient, Oxygen consumption (VO2, ml/kg/min), VE/VCO2 slope, heart rate (HR, bpm), systolic blood pressure (SBP, mmHg), diastolic (DBP, mmHg) blood pressure and distance., Results: The intraclass correlation coefficients at the sixth minute were: HR (r i=0.96, p<0.0001), VE (r i=0.84, p<0.0001), SBP (r i=0.72, p=0.001), distance (r i=0.88, p<0.0001), VO2 (r i=0.92, p<0.0001), SlopeVE/VCO2 (r i=0.86, p<0.0001) and RQ<1 (r i=0.6, p=0.004)., Conclusion: Using the 6CWT with the Borg scale was reproducible, and it seems to be an appropriate method to evaluate the functional capacity of heart failure patients while making sure that they undergo a submaximal walking test.

Objective: The 6-minute walk test is an way of assessing exercise capacity and predicting survival in heart failure. The 6-minute walk test was suggested to be similar to that of daily activities. We investigated the effect of motivation during the 6-minute walk test in heart failure., Methods: We studied 12 males, age 45 +/- 12 years, ejection fraction 23 +/- 7%, and functional class III. Patients underwent the following tests: maximal cardiopulmonary exercise test on the treadmill (max), cardiopulmonary 6-minute walk test with the walking rhythm maintained between relatively easy and slightly tiring (levels 11 and 13 on the Borg scale) (6EB), and cardiopulmonary 6-minute walk test using the usual recommendations (6RU). The 6EB and 6RU tests were performed on a treadmill with zero inclination and control of the velocity by the patient., Results: The values obtained in the max, 6EB, and 6RU tests were, respectively, as follows: O2 consumption (ml.kg-1.min-1) 15.4 +/- 1.8, 9.8 +/- 1.9 (60 +/- 10%), and 13.3 +/- 2.2 (90 +/- 10%); heart rate (bpm) 142 +/- 12, 110 +/- 13 (77 +/- 9%), and 126 +/- 11 (89 +/- 7%); distance walked (m) 733 +/- 147, 332 +/- 66, and 470 +/- 48; and respiratory exchange ratio (R) 1.13 +/- 0.06, 0.9 +/- 0.06, and 1.06 +/- 0.12. Significant differences were observed in the values of the variables cited between the max and 6EB tests, the max and 6RU tests, and the 6EB and 6RU tests (p < 0.05)., Conclusion: Patients, who undergo the cardiopulmonary 6-minute walk test and are motivated to walk as much as they possibly can, usually walk almost to their maximum capacity, which may not correspond to that of their daily activities. The use of the Borg scale during the cardiopulmonary 6-minute walk test seems to better correspond to the metabolic demand of the usual activities in this group of patients.

Exercise oscillatory ventilation (EOV) is an abnormal breathing pattern that occurs in ~20% of patients with heart failure (HF) and is associated with poor prognosis and exercise intolerance. β-blockers (βb) are prescribed for most HF patients; however, their effect on EOV remains unclear. We evaluated the effect of βb on EOV in HF patients with reduced ejection fraction (HFrEF). Fifteen patients diagnosed with HF, ejection fraction < 45%, aged from 18 to 65 years, were included before starting βb therapy. Patients underwent clinical evaluation, cardiopulmonary exercise testing, echocardiography, laboratory exams (norepinephrine levels, B type natriuretic peptide) at baseline and after βb therapy optimized for six months. Presence of exercise oscillatory breathing was determined by two experienced observers who were blinded to the moment of the test (pre or post). Fifteen patients (1 female), aged 49.5 ± 2.5 years, with HFrEF, NYHA I-III enrolled in the study. The etiologies of the HFrEF were idiopathic (n = 8) and hypertensive (n = 7). LVEF increased after βb therapy from 25.9 ± 2.5% to 33 ± 2.6%, P = 0.02; peak VO 2 did not significantly change (21.8 ± 1.7 vs 24.7 ± 1.9, P = 0.4); VE/VCO 2 slope changed from 32.1 ± 10.6–27.5 ± 9.1, P = 0.03. Before βb initiation, nine patients (60%) had EOV, but only two (13%) did after optimized therapy. McNemar test was used to evaluate the significance of the association between the two moments (P = 0.02). In patients with HF, medical therapy with βb can reverse EOV. This may explain why these patients experience symptom improvement after βb therapy. [Display omitted] • The pattern of presentation and the clinical course of EOV suggest distinct pathophysiological mechanisms during sleep and exercise. • Carvedilol appears to play an important role in normalizing EOV. This effect is independent of the beneficial effects of digoxin, diuretics, and ACE inhibitors. • Patients with HF, especially those experiencing EOV, the maximum tolerated dose of carvedilol should be considered. • Heart failure patients with reduced ejection fraction may merit special attention in the presence of EOV. [ABSTRACT FROM AUTHOR]